Thats pretty dangerous thinking though. Adolf Hitler famously said "a lie told often enough eventually becomes the truth" and then used that way of thinking to commit horrible atrocities.
It's the extrapolation of models that we've created in the present, but those models are only our best guess at the truth. They may be revised in the future or simply not hold for the past.
My eyes are a fairly reliable map, but they're still not the territory. That we are only able to perceive reality by proxy doesn't mean that it doesn't exist, though, it just means that we have to get used to using maps, while remembering that they can be flawed.
> My eyes are a fairly reliable map, but they're still not the territory.
This seems.....paradoxical...ironic?
> That we are only able to perceive reality by proxy doesn't mean that it doesn't exist, though....
True, but potentially misleading/misinformative.
> ...it just means that...
Are you sure? Are you referring to the territory here, or the map?
>...we have to get used to using maps, while remembering that they can be flawed.
We've been using maps since the dawn of man, and a lot of people have substantial, abstract knowledge that this is what we're doing....and yet, look at the mess all around us, and the conversations we have about that mess (though: during these conversations, are the participants discussing the map, or the territory: a) in fact? b) in perception?).
> It was factual that the earth was 6000 years old, until it wasn't.
This is the opposite of the example you seem to think it is. The Earth has always had the same actual date of origin. If it is not factual now that the Earth is 6,000 years old, then it wasn't before either. The whole argument here is that people's perceptions and reality can in fact be different.
I would argue that factual past is unprovable without some sort of visual evidence, and even that can be manipulated...especially with AI on the rise. The problem with your point is that EVERYTHING is parsed through your perception, and you can just as easily make the point with the same logic that you can't prove that what you are currently experiencing is present reality.
What actually happened is unprovable without some layer of trust once the event leaves the affected. For example, I ate a grapefruit for breakfast. That is a fact. However, I have tossed the peel away and I am communicating that I ate it with a stranger over the internet. For all you know, I could have eaten cookie crisp. If you and enough people get together and collectively believe that I ate cookie crisp, the public belief will be that I ate cookie crisp. However, that does not change the fact that I ate a grapefruit.
Given that, there are two, and only two possibilities:
Either
-my perception of reality is inherently opposed to objective reality
or
-the world, for some reason, is gaslighting me into thinking I ate a sandwich and the objective reality is that I ate a grapefruit.
See, my problem with this "philosophy" that objective reality does not exist is that it enables abusers. Have you ever seen the movie Gaslight? Its a classic. This poor woman lives with an abuser...someone who is committed to making her think that she is crazy. He contradicts everything she does and says, sets up evidence to objectively prove that she only imagined herself doing it, and keeps her under his thumb through those means. In the end of the movie, its revealed that none of the evidence is real and that she is sane. To combat against these types of people, its important to be sure of your own reality and only change if evidence is overwhelmingly pointed in the opposite direction. Even then, question these changes in belief heavily. Otherwise, you will believe just about anything anyone says.
No, that was never factual. Radiocarbon dating gives us evidence, factual without the lense of perception or opinion. Saying the earth is 6000 years old is just repeating propaganda.
You're begging the question. You started with: assume there is a factual past of where you were. And then argued: there is a factual past.
I'm not enough of a skeptic to say "don't trust the models of the past"; memory turns out to be a pretty good model. So does carbon dating.
But the reason you say "you were not there and did not commit the crime" is because you don't remember being there. Maybe you even remember being elsewhere. But that doesn't mean it's true, memory is fallible.
You might say that you even have photos of yourself somewhere else at the time. But if there were photos of you at the crime scene, would that change what the past was? Maybe your memory is shoddy, or maybe the photos are fake.
Human instincts only apply to the systems that they're "evolved" to handle (or the systems we can readily observe and learn from).
Think about big systems. The moon is a ginormous rock that's so big it is visible from thousands of km away, but it just hangs in the sky because it's moving so fast it can cheat gravity, but we can barely even see it move. Or think about how a star can somehow explode because it starts running out of fuel (and our sun is just yellow hot - you can do that with a blow torch, but it's powered by a nuclear explosion - I guess it's got quite a bit of surface area?). And little things are even weirder, consider how fast the proteins in your cells bounce around. Then there's quantum - our gut intuition is so out of its comfort zone it's basically meaningless.
I used to work at camp. You didn’t need to tell kids about fire; they could figure it out. Don’t touch the fire. Flashlights were too complicated. It’s night, a kid turns on their flashlight, points it in their eyes, says “ow” and can’t see where they’re walking until their eyes readjust. Flashlights are beyond our instinctual understanding of how the world works.
Yes. If we learned something about fire, it's to teach the youngest ones to stay away from it. Nothing more. An unattended and untaught kid will try it, at least because it's nothing like they've seen before.
it's funny you mention flashlights. NO matter how many times I tell people not to point their flashlight at people's eyes, it happens (by accident) over and over. It bothers me a lot because I am very good at getting my eyes dark-adapted and as soon as somebody flashes me, I lose about 10 minutes of dark vision.
The sun being classified as a yellow dwarf does not mean it's "only yellow hot". You can observe that by going outdoors and holding up a white piece of paper and noting it is not yellow in sunlight.
powered by a nuclear explosion
Not quite accurate. The nuclear fusion going on inside the sun's core is not an explosion. In a nuclear explosion, a significant fraction of the fuel in a given area is consumed in an instant. The sun's core on the other hand only fuses its fuel extremely slowly. Pound for pound, the sun's core generates less heat energy than mammalian muscle tissue. It's just that there's so much of it that the heat energy is extremely well insulated.
The sun is the color it is because its surface is 5500 Kelvin, which we have defined as white. The sun is cooler than most visible stars, so it can be called yellow by comparison.
The sun appears slightly yellow because the atmosphere scatters blue light more than the rest. The result is the sky looks blue, the sun is slightly yellowish, and the cumulative light (both directly from the sun and diffuse light from the sky) is white. Outside the atmosphere, our sun appears proper white.
I just need retrocausal information on the stock market, world events, and any threats to myself or my monopoly on retrocausal information access. That's all.
Perfect response for the subject being discussed -and- your user name -and- a summary of your namesake from of a couple of amazing books by Charles Stross.
Well, of course, what happens tomorrow dictates what happens today. It's hard to be sure about what happens tomorrow. Then again it's hard to be sure about what happens yesterday. It's not a one-to-one relationship, but there are striking similarities.
The complaint (a very valid and important one, imho) is that physicists are ~inadequately curious about philosophy - this is the current state of affairs.
To make this no longer be (at some point in the future) the state of affairs, how could it be done (make it "in fact")?
"Why not?" seems like a decent first attack to the problem - why are physicists (or, scientists in general) so bad at philosophy? For one, I would nominate the "When you have a powerful hammer, everything looks like a nail" psychological phenomenon, as one plausible part of the puzzle.
“Everything looks like a nail” strikes me as an accurate description. Dominance of natural sciences provides this philosophical bias towards physicalistic monism, and physicalism in turn limits how those sciences evolve.
As a non-physicist I'm not sure I'm interpreting this correctly. Does this essentially mean that all states in time already exist and our consciousness is just traversing this 4D space in one direction on the time axis?
If so, does that mean that the big bang could actually be the end of the universe and we're just experiencing time in "reverse" toward an initial starting state that we perceive as the future?
Reminds me of the Tralfamadorians from Slaughterhouse-Five. They are able to see in four dimensions so humans appear as fetuses at one end of the four-dimensional person and dying at the other end.
Interesting concept. I wonder if it's compared with spatial 3D space, then how large would the 4th dimension of time be if it were to fit the timeline of a human lifespan
A natural interpretation leads to time being very large and us moving very very fast through it.
It's convenient to model our movement through space-time as occurring at the speed of light. Thus, the faster we move in space, the slower we move in time all the while the length of our space-time velocity vector is invariably c. We can then imagine 1 second of time being interchangeable with 299,792,458m.
Surely reminds me of Harry Potter and the Prisoner of Azkaban, where Harry is saved by himself as he at some point in the future travels back in time to save himself.
While most laws of physics may be time symmetric, the laws of thermodynamics are not - wherever there is a gradient in entropy.
In very informal terms, anywhere where there is very low entropy (higher order), any direction away from that will likely (to the point of certainty) be in a direction of higher entropy (lower order).
For instance, if you have a jar of red & blue marble, with high order (such as perfect alternating layers of red vs blue marbles) then any disturbances (such as shaking the jar, reaching in and moving a handful, …) will almost certainly reduce order.
And no practical amount of shaking the jar will ever return the marbles to a high order state again.
Even though any close up video of the marbles being jostled will reveal the same physical properties and behavior for the marbles, whether played forward or backward.
So at the individual marble level, laws are symmetric.
But at the jar of marbles level, one direction of time looks very different than the other.
We, and the particles that make us, and our environment, are the marbles whose configuration is more disordered the further in time we get from the Big Bang.
So we perceive the time direction away from the Big Bang as the future, toward the Big Bang as the past.
And the statistical “force” of increasing entropy provides the useful energy we use to survive, learn, create useful islands of order, in the greater sea of increasing disorder.
> And no practical amount of shaking the jar will ever return the marbles to a high order state again.
This can't be true. Take the case where there's only 2 marbles, it's likely that at some point that shaking them will return them to the original state. For higher numbers of marbles the probability becomes lower and lower, but is never 0.
With enough marbles, the discrete distribution behaves like a continuous distribution. The point probability of a continuous distribution is infinitely improbable -- in other words it is 0.
I'm neither a mathematician nor a physicist, so I'm not nearly informed enough to elaborate on the subject properly, but I would note that the axiom of choice is not proven, and while you can mathematically divide a continuum into infinitesimally small sets, you cannot do the same to physical matter. From my understanding, many of the contradictions between classical and quantum physics arise at this boundary between the discrete and the continuous, where classical physics generally assumes continuity while quantum physics is constructed around discrete quantization mostly independent of time.
Again, I'm not a physicist, but I think it's telling that the validity of continuum mechanics [0] depends on a model and multiple assumptions. I have no trouble agreeing with your original statement, "with enough marbles, the discrete distribution behaves like a continuous distribution," when speaking mathematically, but mathematics by its nature is an idealized model of the world - I'm not willing to accept that it's objectively representative of physical reality. The discussion we're having here is one of metaphysics, so it feels a bit like the height of hubris to use mathematics as the tool for describing objective reality, because metaphysically, we cannot say that mathematics is anything other than a tool we've constructed for approximating the model of the world as we understand it. Considering the subject of this post is about retrocausality, we're already throwing out some pretty wild ideas, so I think it's a bit hubristic to dismiss them by citing a branch of mathematics that assumes the existence of countably infinite sets [1].
This whole thread hinges on your not giving credence to the word "practically" , as in "approximately". No countably infinity needed, and Continuum Hypothesis isn't relevant at all in any way, as it is aboit uncountable infinity. Until you explain what you are trying to say, you aren't saying anything meaningful. The one showing hubris here is you, tossing around technical terms don't admit you don't understand.
> The one showing hubris here is you, tossing around technical terms don't admit you don't understand.
Hence the disclaimer. I just think this stuff is fascinating. If you're interested, this is the article that originally got me thinking about these ideas as they relate to the flow of time: "Does Time Really Flow? New Clues Come From a Century-Old Approach to Math" [0]. It's effectively an appeal to intuitionist mathematics and a rejection of constructivism, where - simplified - every particle since the big bang can be assigned some "number" that describes its position on its world line, with a precision that is finite, but always increasing - and it's this increase in precision from which emerges the "flow" of time. If you ctrl+f the article for "continuum," you'll see some better constructed arguments for what I'm trying to argue, e.g.:
> Moreover, the continuum can’t be cleanly divided into two parts consisting of all numbers less than ½ and all those greater than or equal to ½. “If you try to cut the continuum in half, this number x is going to stick to the knife, and it won’t be on the left or on the right,” said Posy. “The continuum is viscous; it’s sticky.”
The impression I'm left with is that the difference between constructivist vs. intuitionist mathematics (which rejects the law of the excluded middle) has some parallels to the difference between eternalism (there is a past, present and future) vs. presentism (there is only the present).
As a layman, I just can't help but notice the same patterns come up again and again when looking at unresolved problems between classical and quantum mechanics, namely those that lie at the boundary between the continuous and discrete. FWIW, I asked ChatGPT for some unresolved mathematical problems that might relate to this, and it came up with: The Continuum Hypothesis, The Axiom of Choice, and The Riemann Hypothesis, all of which it admitted are possibly impossible to prove because they're effectively unfalsifiable. (I also showed it this entire thread, and it agreed with your critique of my arguments, but also that every argument in the thread is unfalsifiable - and then it pointed me to the Boltzmann Brain paradox).
Indeed, the original claim treats mathematics as a modeling tool, not philosophy. Nevertheless, it is my belief that untestable hypotheses about True Reality (should it even exist) are not debatable without causing migraines of epic proportions. There's no physics without mathematics -- as physicists say, shut up and calculate.
Mathematics applies insofar as it can model the subject under discussion. It's a great tool for, dare I say, 99.999999...% of practical problems. But mathematics is an imperfect model of objective reality that cannot resolve metaphysical problems like Zeno's paradoxes [0]. Any discussion of retro-causality is inherently one of the philosophy of space and time, which is the domain of metaphysics, not mathematics, so we can't necessarily apply familiar mathematical lemmas to resolve the problems it creates.
The number of possible states asymptotically approaches infinity, so we can model it as such. You can get a more "accurate" model using more math (with measure theory), but the terms will coalesce such that they are negligible.
Any point is infinitely improbable when sampling with infinite precision, only because this calculation is not computable.
Even if the point probability is 0 or approaching zero very fast, some event occurs with probability 1.
The probability that life would evolve on a blue planet that its anthropomorphic inhabitants will come to call Gaia or Earth, has as a star Sol, in this corner of the Milky Way, in this particular local group and so on is zero even if we limit ourselves to just the observable universe.
At the same time the probability that life will exist at some planet at some solar system at some galaxy at some local group and so on, is practically 1.
That is to say, depending on how you categorise and count said marbles, the reordering may occur.
While any individual marble will not be at its place with P=1. You can still end up in a situation where the marbles are ordered in layers.
The whole thing regarding entropy is concerned with a closed system. You can very much exchange energy to decrease entropy, but said exchange is a) leaky, and b) implies that the system is not isolated.
A probability of zero does not mean that the event is impossible. When we refer to probabilities we are talking about probability densities. Infinite precision is a useful modeling tool in the same way that approximations of pi are useful.
I think I was misunderstood. My comment regarding infinite precision was mostly aiming to argue that any single point has probability zero but an event still occurs.
This was then used again when mentioning earth to argue that depending on the definition of "order" here:
> And no practical amount of shaking the jar will ever return the marbles to a high order state again.
It is entirely possible to reach a state of higher order if you don't require that individual marbles don't hold the same arrangement relative to adjacent marbles, meaning that any permutation of marbles with identical color is acceptable.
This happens because the event you are asking for is a very large subset.
Define "large", at least in an estimate. Dividing two astronomically large numbers is not easily estimated. And define "entirely possible". Yes, could happen once, maybe, in the entire Universe is entirely possible. Anything is "entirely possible" because humans are not omniscient, so we have to start from Bayesian priors.
In physics, nothing can be measured exactly, so exact events are in fact impossible. Measurements are approximate, and thus have finite extent, and thus can have nonzero probability.
This whole thread is silly, The 2nd law is about probabilities which are asymptotically 0, so small in practice that we could never do experiments to frequentist probability empirically, using "jars of marbles" with more than 100 marbles", let alone trillions of trillions of particles.
That is a great point. The laws of thermodynamics exist as a logical consequence to fundamental statistical principles. It is statistical mechanics that gives rise to entropy, not the other way around. (hence the beautifully elegant equation S = Kb*ln(Omega) where Omega is the number of microstates)
I realize that programmers are not always good scientists. Yet some claims are absurd in ways that I now believe this phenomenon necessitates rigorous study.
you're correct. In stats/thermo class there's a commonly taught "what's the probability of all the molecules of air in a room spontaneously moving to <extremely small location>". The problem is that shoving all those molecules into a tiny location woudl increase the pressure tremendously, sending all the particles in directions that would eventually return to a uniform distribution.
IIUC my professor right the probability is non zero but is practically impossible for a large number of incompressible spheres.
> For higher numbers of marbles the probability becomes lower and lower, but is never 0.
Exactly. It doesn’t take a very large jar to make a return to an original state practically impossible. But even for two marbles, shaking them to return them to their original locations costs a fair amount of organized energy.
And that is organized chemical energy in your muscles, which you are dissipating as disorganized heat energy due to your efforts, increasing the total disorganization.
And the marbles are microscopically wearing down, shedding compounds. The jar is also wearing down. Both becoming less organized.
So even with two marbles, overall entropy continues increasing.
We can locally reverse entropy, only at the cost of actually increasing entropy in total.
- Organizing your day takes effort and uses up useful organized energy.
- Computation uses up useful organized energy.
- Your cells, maintaining their metabolism, uses up useful organized energy.
Because cause and effect is more understandable and controllable in one direction.
Everything we do takes advantage of the higher to lower entropy gradient.
We get relatively organized photons from the sun, a percentage get stored in wood of trees, so we can burn that for heat which can drive an engine or generate electricity, with the end result is doing some useful work.
And we don’t actually lose any energy, due to conservation of energy.
But we have now lost USABLE energy, because all our captured energy is now heat diffusely spreading out from our engine into the atmosphere where it becomes uncontrolled DISORGANIZED and therefore no longer usable.
So clear causes tend to occur in past of clear effects.
For large objects.
But again, if you watch videos of individual marbles bouncing around, forward or backward, you see just as clear chains of cause and effect in either direction.
Not sure if you appreciate this, but if you repeat the shaking experiment enough times, you will see it return to perfect order- at some exceptionally tiny probability. I'm pretty sure you are saying that but instead of "practical amount", it's easier to say it's just exceptionally unlikely.
So I think I understand this argument and it makes sense to me (at the moment). To me the (to paraphrase), "increasing as we move away from the big bang" stuff seems to lead right to the idea that the expansion of the universe is what we perceive as the passing of time, but I never hear any one knowledgeable say that. Is there some obvious reason that it's not that succinct?
You're actually the lamination of what you typically consider to be yourself, across all time periods in which you exist: a 4-dimensional spacetime worm.
Must it be "the" time axis? Might it instead be "our" time vector? Maybe there are alien civilizations right next door which we fail to recognize as life because our time vector is orthogonal to theirs. Instead they're just gamma ray bursts to us.
– The laws of physics are essentially time-symmetric, and they have no concept of causation or of a preferred direction of time. In principle, the future causes the past as much or as little as the past causes the future. Physics effectively only says they have to be consistent with each other, as related by the laws of physics.
– The apparent directionality of time that we perceive is suspected to be tied to the entropy gradient we are on. See the “past hypothesis” for example [0].
> Does this essentially mean that all states in time already exist and our consciousness is just traversing this 4D space in one direction on the time axis?
– I would say that all moments in time are equally real, including our consciousness at any given moment. There is no actual flow or “travelling”. The flow we perceive is merely an illusion caused by the fact that we only remember the past and not the future (which again may just be a consequence of the entropy gradient we are on). This is known as the “block universe”, or as “eternalism” [1]. The opposing view that only the current moment is real, and that the future differs from the past in its “realness”, is known as “presentism”.
– Note that any notion of “travelling” through time implies that you can draw a 2D diagram of where in time you are at each point in time, or which point in time is “real” at which point in time (in the sense that a moment in time isn’t real until time reaches that moment, but after that it is real and cannot be made unreal again), thus implying two dimensions of time. That doesn’t make any sense, and thus my personal conclusion is that the “presentism” view is nonsensical.
> In addition to potentially rescuing concepts like locality and realism, retrocausal models also open avenues of exploring a “time-symmetric” view of our universe, in which the laws of physics are the same regardless of whether time runs forward or backward.
Usually the fundamental laws are regarded as time symmetric already.
What does this mean:
> Instead, retrocausal models suggest that there is a mechanism that allows circumstances in the future to correlate with past states.
Surely future states inevitably correlate with past states?
Perhaps it all makes sense but that article doesn't make a compelling case.
Measurements are adjoint to state preparation. Depending on what you measured you can prepare a special state at that time to make the system time reversal symmetric.
Not an expert in this area at all but there have been some experimental findings in the last five or so years that suggest the possibility of retrocausality.
This is just one example I found but I think there might be another experiment from a few years ago that was getting some attention at the time (although I might be confusing it with a theory paper):
Yes, of course. But that is not how correlation is usually expressed. And it also doesn't explain what it means. It just sounds like philosophers doing some hand waving.
What can it mean to have an effect propagating into the past? Surely our usual definition of time is simply a series of events. If so then it always points in one direction for the entity sitting at the leading edge, the current event is always succeeded by the next event.
All I have to go on is the article, perhaps the source material makes more sense.
“It’s important to emphasize at this point in time, whatever that means, that retrocausality is not the same as time travel.”
The funny line there is at this point in time. The whole article is about how the future influences the past so… at some point in time retrocauslity will be the same thing?
Retrocausality is like time being cooked spaghetti instead of dry. Or even macaroni. The world line is not "parallel" to the time line. Like the One Electon Universe idea ofositrons as time-reversed electrons.
The article doesn't define time travel precisely, but presumably they mean discretely jumping ahead or back without passing through interventing moments.
Isn't it just a matter of perspective/terminology?
If in my physics theory I redefine that past=future and future=past then I have a physics theory where the future influences the past, and very strongly so.
while I might buy that the past is strongly influenced by the present (“facts” change over time), I don’t think we have much of a model for the future to say much of anything about how it influences the past.
Or, I guess the point is, maybe it’s the same thing.
Interesting because it messes with the school of thought that everything is determined already and we're just following a sequence of actions that arise from the starting conditions of the universe. If causality is broken then maybe we have free will?
That's a very lazy school of thought though. It's just atheistic Calvinism, a tautology masquerading as a "philosophy".
Calvin believed in pre-destination (your fate and every decision you make is decided before you exist) on the grounds that, because God exists and is omnipotent, what you are doing must therefore be what God wants to happen, both good and bad. After all, God is omnipotent, so there you go.
Today's Calvinists just replace God-driven destiny with nature-driven destiny, but the underlying tautology (X exists, therefore X was always destined to exist, as proven by the fact that it exists at all) remains the same. In fact, it's an arguably more ignorant version of Calvinism, because it requires that one completely dismisses any knowledge they have of probability theory. So it's the "smarter" Calvinism that requires you be ignorant of 20th century mathematical advances.
Hate that crap. The only people I hear talking about it are silicon valley utopians, which is probably the other reason I hate it.
> In fact, it's an arguably more ignorant version of Calvinism, because it requires that one completely dismisses any knowledge they have of probability theory
No to pick too many nits, but I think it is well established that knowledge of formal sciences (i.e. mathematics) does not impart knowledge about natural sciences (i.e. physics). While maths a useful tool, there are no established rules of inference for reality, and without rules of inference you can't really make claims on infinite sets.
Natural sciences allow us to find mathematical constructs that make good predictions within specific constraints or that have not yet been falsified, just because something is true in probability theory does not make it true in reality.
> In fact, it's an arguably more ignorant version of Calvinism, because it requires that one completely dismisses any knowledge they have of probability theory. So it's the "smarter" Calvinism that requires you be ignorant of 20th century mathematical advances.
I entirely fail to see how probability theory means it's impossible for the universe to be deterministic.
So my decision to have a ham sandwich for lunch is determined by some meta-universe that created the starting conditions for this universe, and allows for the breach in causality? Or somehow is involved in the backwards-arrow of quantum events that the article talks about so the universe cannot turn out any other way?
I dunno, seems like a "God of the gaps" thing - we can speculate on meta-meta-universes endlessly. Including one where my decision to have a ham sandwich disturbs the state of a yet higher dimension that sets the starting parameters of your higher dimension and once again I have free will.
Right, physicists seem to generally agree there are parts or dimensions of the universe we cannot directly measure. If scientists can't predict whether you will eat a ham sandwich for lunch or not, it won't be clear if they can't predict it because you have "free will" or because we have limited access to information on how the universe works.
Scott Aaronson's "Ghost in the Quantum Turing Machine" tackled this question in a way I found enlightening. It's a bit of a dense read (I needed a plane trip to sit down and focus on it), but it presents a compelling case for the possible reversal of time arrows when it comes to the effects of quantum indeterminism on macro scale interactions. In short: what if humans, somehow, someway, have the ability to "influence" the resolution of unobserved universal start-state quantum noise in order to affect our "will" onto the universe? Furthermore, what experiments could be done to validate or invalidate aspects of this hypothesis?
That seems crazy - that my decision to have a ham sandwich for lunch had to be propagated all the way back to the start of the universe in order to happen ;)
And yes, provability is a major problem with all these kinds of theories. We don't have a parallel universe handy as a control, and just saying "I am not going to have a ham sandwich tomorrow" isn't a viable experiment.
I interpret it as a sort of entropic antennae... each person (brain? qbit?) is tuned into what might be considered an allocated "entropy bandwidth". Some decisions, like whether you eat a ham bandwidth tomorrow utilize* practically none of that bandwidth. Others, what you might consider "major life decisions" might utilize* a ton of bandwidth. Some people might be gifted with a "larger" antennae, allowing them to utilize* a higher amount of entropy per second, or per lifetime. We might call these great artists, or generally any genius-level intellectuals. Alternatively, bat-shit crazy people.
*: On "utilize". A central debate (the central debate?) seems to be what sort of "state access mechanism" this maps to in our lexicon: "{reading|writing} {global|local|shared} {bandwidth|memory}"
>had to be propagated all the way back to the start of the universe in order to happen ;)
Technically, casualty required that anyway. My understanding that it's infinity in space, not time that matters here. i.e. predicting your decision to have a ham sandwich may require predicting the entire universe and since we're part of the universe and can't look from 'outside' that decision would be unpredictable from inside the universe.
>And yes, provability is a major problem with all these kinds of theories.
I think showing that quantum effects are negligible for human brains would do, at least regarding your decision to have a ham sandwich?
Mmm, not really unpredictable, it is easy for thought exercises to avoid the dirty real world, but in the real world, Large Language Models have recently proven that many quite difficult abstract probability exercises, when taken to the real world and applying training, can be succesfully solved well beyond our most wildly expectations of precision, speed and accuracy.
So yes, the prediction of the decision to have a ham sandwich tomorrow, for any given person is now, by the state of the art of applied mathematics and information science, a relative doable - if not plain easy - feat.
And according to some hypothesis, the brain could be doing this exactly kind of predictions, even more better than LLMs, with more accuracy/speed using way less energy.
> the prediction of the decision to have a ham sandwich tomorrow, for any given person is now, by the state of the art of applied mathematics and information science, a relative doable - if not plain easy - feat.
Sure, the LLM may be able to guess by reasoning (e.g. 'He always eats ham sandwiches for breakfast and he probably wouldn't break his routine'), the same way we could guess at another person's behaviour, but we're talking about reducing the brain into a deterministic input/output machine, which is a far larger ask.
Now if you said 'doable' that may be right in the long term, but 'easy'? Absolutely not. There's no current way to feed 'me' or 'you' into an equivalent LLM. The human brain has more axons then there are stars in the galaxy and we are nowhere close to even mapping these connections.
>The brain could be doing this exactly kind of predictions, even more better than LLMs, with more accuracy/speed using way less energy.
That's definitely an option. The fact that many of the brain's operations could be done by LLMs is a strike against the original thesis.
The compatibilist view is that there is no contradiction between free will and determinism, because free will refers to macro states and determinism refers to micro states.
In addition, in the many-worlds view of quantum mechanics, we don’t follow just a single sequence of events, but all physically possible sequences of events, where the points where sequences branch off each other can correspond to different decisions we “freely” took. Meaning, when we make a decision, all applicable options of choice will become actual reality.
Compatibilism is a fancy way of saying "free will so much does not exist that what determists call free will isn't even a valid definition to use as a starting point for investigating an answer." It's not an answer to the question, it's a denial of it.
Another, simpler interpretation of Compatibilism is "if free will doesn't exist, then believing it exists or not has 0 effect on anything, because our beliefs are predetermined, and so at human scales the answers Yes and No are equivalent in all observable ways".
My favorite sentence on free will comes from Chomsky (who I think was probably quoting someone else): "if we don't have free will, then why are you arguing the point?"
Causality isn't broken; the universe is "simultaneously causal and teleological," because it's superdetermined.
There also isn't any free will, because there isn't actually any agent who could have it. Actions we perceive as volitional actually arise in the brain up to 7s before we "choose" them. The sense of a "me" is a post hoc add-on that claims credit for everything, in order to unite the disparate phenomena that comprise the sense of self.
There isn't actually any "me," and recognizing this is what the word "enlightenment" refers to.
Again this seems like a "God of the gaps" thing - if this universe isn't strictly deterministic then it's superdetermined by a meta universe, and so on
I think it's the opposite. You need a "God of the gaps" in the form of a "person" (actually a collection of phenomena. + the phenomena of identification with these) to explain free will and agency, which defies experimental evidence.
The comment that superdeterminism requires a higher-order determinism, which itself requires a yet-higher-order determinism... I think you're confusing it with a causal mindset. If the universe is effectively a recording, why does it need any ultimate cause? Causal thinking would only make sense from a perspective within that recording.
Of course we want to know "why is any of this here?" But what if the ultimate question doesn't actually have an answer?
> There also isn't any free will, because there isn't actually any agent who could have it.
The compilation of each possible Play in an Extensive Normal Form Game into a cellular automata can constitute a refutation by counterexample of your claim. It satisfies the agent condition through congruence with the technical language defining the concept of agent in artificial intelligence literature as it relates to agents in multi-agent multi-step decision theory problems. The condition of non-deterministic policies is found and shown to be optimal by Nash's justification for an mixed strategy equilibrium. The underlying mathematics that leads there is proven via Russel and there exists various proofs of the desiderata of probability from others which can begin atop that. Furthermore by compiling the formal system to get a physical system we create the ability for a logical analogy between the formal system and the physical system through Aristotle's analogical congruence concepts. We can count the cell configurations and we can count the transitional structure, but this is mostly a formality since we know through the definition of the compilation that they must agree. As far as I can tell at every single step in the laddering up there are proofs from the basics of logic to the mathematics to the use of probability to the justification through utility theory and even to the computational universality necessary to create the physical embedding of the agent in our reality.
The prior conception of guess appears laughable posterior to computation and comparison with evidence, but is just science prior and seeing it is wrong is hindsight bias posterior. It might sound laughable, but it is actually the case that it is not a laughing matter [1]. In like manner, but slightly different and perilously close to being anti-scientific is that you don't know until the observation whether guesses would go one way or another.
I'm saying your self-concept is only a useful abstraction. It's an evolutionally beneficial illusion that there is any entity called "me" that chooses which action comes next.
The mathematics of intelligence in multi-agent decision problems implication gives us informed guesses about what we should expect to see if an agent has free will versus if they don't. You are arguing with words like illusion, so I don't think you realize this, but what you actually need to provide to have your actual position be the consequence of experimental evidence is evidence of extreme compression being possible. Illusion? It is the evidence for agents, not evidence against agents, according to the theory informed guesses.
There is this story about a village of blind men and elephants. You are like a blind man from that village, saying that the elephant must be abstract because you felt a footprint of the elephant. Try playing with an elephant carving. It predicts footprints when you press it it into the ground. You can totally guess before you touch the elephant on the basis of the carving. The decision to focus on the untestable is a commitment to a hindsight fallacy which experimental investigation would likely refute.
I get what you are trying to say, but it isn't true. This is the long version that explains why and goes through the implications at each step showing the hypothesis, predictions they make, and why your views don't make sense. You should read this if you don't think my other post makes sense, but if it just clicks you don't need to read this.
H0: Free will predicts in advance of a decision problem that when a decision problem is resolved you cannot always predict the result.
H1: A lack of free will predicts of a decision problem that when a decision problem is resolved you can always have predicted the result in advance of the result, because there was only one possible resolution.
Complete Refutation of H1: The existence of halting problems. A self-reference in a decision problem refutes H1, because the self-reference
Additional strong evidence against H1: All the most successful epistemological frameworks suppose a superposition over positions which on attaining information about the next position resolves, not to a position, but to a new superposition. For example science does this. It believes we don't know for certain the theories, but we conjecture guesses and use observations to test them.
Implication of failure of H1 and the failure to refute H0: There exists a self-reference, a sort of self-concept, which prevents the resolution of a prediction prior to the resolution. Self-reference exists as a thing which must be computed.
Okay. So now we pick back up in the mathematics that deals with self-reference in game theory. In it we find equilibrium concepts which are defined with respect to self-reference and proven relative to self-reference considerations. These proofs show that the solution structure contingent on self-reference is non-deterministic.
Implication: Not only does self-reference exist, but the consequences of self-reference is the use of self-reference to refute self-referential prediction or to support self-referential prediction on the basis of utility of doing so or not doing so.
So now we know a self-reference must exist, we also know it predicts a refutation in some cases of the ability to predict it. We can also see that if the self-reference didn't exist, it would imply that there was no structure which wasn't computationally irreducible like self-reference structures are.
H3: We will see everything is predictable from the information contexts available, because agents don't exist. Example predictions: that all physics will be determinable like the position of a planet is determinable.
H4: We will that some things are not predictable, because of the existence of illusions that prevent resolution and which contain a self-reference consideration.
What we actually observe is H4. We observe H4 in at least one case, so we can't infer from H3 that we can reject H4, because H4 already rejects the safety of H3.
Let me give an example: Some deer in Africa don't see orange. Tigers, to us, are orange. To the deer they are green. The tiger color is decided by a self-reference consideration with the deer perceptual system. The deer is not going to be able to predict the future state of all tiger like we could predict the planets, because the deer is caught in a superposition with respect to a tiger's presence. When it observes a tiger, this looks the same as observing a bush. Therefore, even if it sees a bush, it can't predict that it can always model the consequence of a bush. Therefore, if we see a planet, it is incorrect to assume we can always predict the consequences of seeing a planet.
So now you can understand, if my other comment didn't click, why appeals to illusion are actually evidence for self-reference, not evidence against it. So feel free to read that comment again to see if it now clicks.
And yet doesn't it defy probability that such raw physical determinism would lead to us having this discussion? And if not, is it not amazing that simple subatomic physical applied to a gaseous soup leads to us discussing these questions?
To the first question, not in the least. This discussion is also superdetermined, including the illusory sense of a "me" who "chose" to write these comments.
To the second question, yes. It's beyond comprehension and wondrous. It's maximum novelty and total absurdity.
Might be worth it to brush up on computationally reducible phenomenon and computationally irreducible phenomenon. Breaking determined systems into these constituent parts lets you conjecture with respect to intelligent agents. Critically it shows that arguments from observed inability to successfully model the self are evidence for, not evidence against, the presence of an intelligent agent. The enlightenment view misattributes the evidence for agents as evidence against agents.
An anti-enlightenment koan could be: The student came to the master and asked, “Why are tigers green?” The master responded, “The deer they are hunting can’t see orange.” The student then asked, “It is not therefore it is? How mysterious and inscrutable your answers!” But from that moment onwards the master was de-enlightened.
I am fascinated by physics but my original background is math. This all seems fascinating but also sort of baroque and far from experiments like much of QM and GR lately.
I used to believe that the world is lazily loaded. That means the first moment I see something (e.g., a world map) is the point where all the past history to consistently explain the observation gets "locked in".
Was coming to say something like this. Gets to some fun conclusions - ex. paleontologists invent dinosaurs by looking for them.
Another angle on it would be showing that the universe has multiple possible levels of detail - that objects behave like newtonian point masses most of the time, that digestion is replaced by a simple hunger meter when nobody's paying attention.
From this direction, time's main function is compressing "now" so there's more space for something else later.
I'd be willing to believe that everyone has a god-given amount of universe rendering time that can be allocated in different ways, and that other people's attention stacks with it in a complex, layered way.
That would also mean that when I don't see or hear other people, they don't "exist" as physical things that can be seen or heard until I encounter a situation in which they would be.
It's the same as "If a tree falls in the forest and nobody is around to hear it, does it make a sound?"
But then again, that information has to be stored somewhere right?
Like, if a tree falls in the woods and nobody is around, sure you can say it isn't being perceived so it won't be "rendered" but the moment someone walks in the forest and sees that fallen tree, it would need to be rendered from some information about the fall and information of how it looked before the fall. That information would have to be sitting somewhere in limbo waiting to be rendered. So why not just actually let it sit IN the rendered "realm" and now you have one place for data to live in. You save on data transfer fees too.
> But then again, that information has to be stored somewhere right?
As a collection of probabilities stored as a wave.
If a bank account has a 50% probability earning a penny every second, the bank doesn't need to store all of the intermediate values for every "clock tick", but instead calculate how much has accumulated since the last time someone checked the account and store that value with a timestamp.
The idea is that the universe "cheats" by replacing a computationally expensive process (a tree falling, breaking into pieces, being eaten by insects, moss growing) with a series of cheaper, "good-enough" replacements, based on the level of scrutiny.
Not existing is the cheapest.
Then, broad strokes, location and orientation
Then pieces, level of decay
etc,
and moving between the layers is you spending your attention budget to force the universe to do more work.
This thought experiment implies that humans, or conscious agents, represent a highly concentrated source of entropy, currently (mostly) confined to planet Earth. Meanwhile, in the vastness of space, most of the mass has settled into some relatively deterministic equilibria, with no conscious agents to alter the course of its future. Yet we're down here on the blue planet messing everything up.
Coupling this thought with the simulation theory, it makes me wonder how the simulation would respond to increasing entropy over a larger volume than just our local system. That is, if we send a bunch of biological/artificial agents in all directions throughout the cosmos and let them wreak havoc, would it crash the simulation? Or what if we just smash a bunch of asteroids out of their stable orbits and let their disruption cascade throughout the system? Or maybe we've already messed everything up by broadcasting highly entropic radio waves throughout a spherical volume with a radius of ~100 light years?
The first time somebody showed me an article in Vice it was ~2010 and the article was about the style and fashion of how bricks of heroine were being branded. so ... yeah.
For this community it might be useful to stress that the vast majority of practicing theoretical physicists is not in the least worried about any interpretation of quantum mechanics.
I would argue that the idea instead is to try to make predictions for future experiments. In the case of quantum gravity, especially string theory, these might be thought experiments (what happens if you fall into a black hole), technically infeasible experiments (what would a particle accelerator with the size of the solar system produce), or even completely hypothetical (what if the universe would have eleven macroscopic dimensions) but that does not change the underlying mindset.
When it comes to the interpretation of quantum mechanics there is just nothing left to explain. There is no experiment that decides between different interpretations, so that is it as far as most physicists are concerned.
The ideas in the linked article suffer from the same fate: there does not seem to be even a hypothetical way to test them, and the topic is therefore considered one of philosophy more than physics.
Still, can't alternative formulations inspire new physics? Like Lagrangian/Hamiltonian formulations of classical mechanics making the step towards QM easier?
>"But what if this forward causality could somehow be reversed in time, allowing actions in the future to influence outcomes in the past? This mind-bending idea, known as retrocausality, may seem like science fiction grist at first glance, but it is starting to gain real traction among physicists and philosophers, among other researchers, as a possible solution to some of the most intractable riddles underlying our reality."
Linguistics: retrocausality -- is going into my 2023 lexicon...
> It may seem eerie to our brains, which process events sequentially, but the history of science is also littered with examples of human biases leading to bad conclusions, such as the Earth-centric model of the solar system.
Slow down. Assuming that time moves in one direction is not comparable to geocentrism.
It is because in both cases, you can work out that you'll never make an observation that really proves it one way or the other, but you might come up with some laws of physics that are more conveniently expressed in one way than another. They're both ultimately questions about your coordinate system, and in fact it is easier to invert time than it is to work out how everything's supposed to function in a rotating+sun-orbiting+precessing+... coordinate system.
If we reverse time and this implies running everything backwards in physics, do we include gravity in the set of things that are reversed? Then everything would fly off the face of the earth in reverse-time.
" it's literally like playing a movie in reverse" seems overly authoritative for something we haven't observed. I have seen Tenet, but it's a work of fiction.
Have we observed reflected gravitational waves? In reverse-time, where would they originate from if they presumably rippled out into space and didn't collide with anything in forward-time?
.... they would "originate" from all the locations the gravity waves spread to and converge on the source.
Tenet has nothing to do with this- I'm just explaining it as it was covered in my many physics classes that covered the nature of the arrow of time (https://en.wikipedia.org/wiki/Arrow_of_time) and how I interpret it in terms of what seems most likely/least unlikely.
In these "it's like taking a video of throwing a ball in the air and allowing it to land on the ground, then playing it in reverse" examples, I can't help but think of Newton's first law. If an object at rest stays at rest, how does the ball leap from the ground? Where does the impulse come from? Reverse time seems too far fetched for me, or at least the simplified naïve version of it does.
It also seems a bit misleading, since in that scenario a ball is intentionally thrown so that it comes down the same way.
Let's consider something else - imagine an accretion disk of space dust slowly pulling itself together to form a planet. Play that in reverse, and you have the a planet slowly coming apart piece by piece. Imagine reversing the impact that created the moon. The moon comes apart piece by piece, creating an accretion disk around the earth, which then all moves and hits one area of the earth, and there several parts of it (and part of the earth itself) move together to form a separate planet, which then launches itself from the earths surface into space, flies around the sun a few times, and then slowly breaks apart piece by piece into another accretion disk.
If you stop there it looks like you're right, but you also must change the definition of velocity to account for the new time.
v = dx/dt = -dx/du
+F = m dx/du
So the direction of gravity (the force F) stays the same when you flip time. I can explain that without the math by pointing out that if you took a video of a ball being thrown up and caught and played it in reverse, it would still depict a ball being thrown up and caught.
> I can explain that without the math by pointing out that if you took a video of a ball being thrown up and caught and played it in reverse, it would still depict a ball being thrown up and caught.
That's amazing, thanks. The portion where you caught the ball in forward time is equivalent to throwing the ball in reverse time.
If we change the analogy of throwing a ball to firing a gun into the air - does the analogy still work? Since when we fire the gun up, the bullet will travel faster up than it will travel down due to terminal velocity in forward time. How is that phenomenon explained in reverse time?
Instead of predominately striking the bullet in a way that causes it to slow down, the molecules in the air will predominately strike it in a way that causes it to move faster, in what looks like an unbelievable (but still physically possible) run of good luck.
In the way down -sky to gun - the molecules in the air will give it energy to accelerate more than gravity alone would. Before that - in the way up - air molecules will cause it to move upwards at constant speed until conveniently they stop doing so.
> unbelievable (but still physically possible)
Physically possible - but in the same sense that the second law is not a physical law.
So it seems like if we reverse time, we reverse entropy and that as time approaches 0, we would effectively be reversing the big bang and instead have the big collapse.
Another thought experiment that comes to mind is compressed gas in a cylinder. When we open the valve, the gas in the cylinder comes out. In reverse time, the gas would go back into the cannister and the valve would close after the gas went back in. Very low probability of that happening in forward time, though not not 0.
Though it seems weird, because why does the gas go into the cylinder? Because further into reverse-time, something sucked it all out (in forward-time, this machine is the compressor that put the gas in the cylider.) This hurts my brain!
Reversing time on an attracting force still gives you an attractive force. Velocity is reversed, but acceleration isn't.
Imagine a ball being thrown up and then falling down, in a parabola. Reversing a video of that still gives you a video of a ball in a normal parabola trajectory.
The history of the universe channel on YouTube has an episode called 'what is time' that goes over symmetries like this. Lots of atomic/quantum scale interactions are time reversible like this, but not quote all, and that may be where time arrives from.
Well worth watching that episode as it does far better explaining than I do.
It isn't because we have the observations we have. It might be mathematically easy to invert time, but empirically it's not so simple. Mathematical symmetries and expressions are nice, but then the actual physical consequences and requirements (e.g., material, time, energy inputs) sort of force one's hand.
Also, geocentrism is actually disproven by numerous observations, which in fact guided the mathematical formulation of our current physics.
One thing is (almost) certain: the laws of physics as we know them (i.e. the Standard Model and General Relativity) are incomplete ("wrong"). That doesn't mean any old model is equivalent or as useful as either, though.
>Also, geocentrism is actually disproven by numerous observations, which in fact guided the mathematical formulation of our current physics.
The validity of a coordinate system with the earth stationary at the center is guaranteed by the general principle of relativity. To get the stars to circle around it you would add a radially increasing potential in classical mechanics, or some coordinate shenanigans in GR. These coordinate systems are used in aerospace engineering to get convenient expressions of L1 points, etc.
I know it sounds hard to believe, but if you're willing to bite the bullet that "the center of the universe" has no physical meaning, then earth can't be not the center of the universe any more than it can be.
To be honest, I have no idea what you are talking about.
Certainly, there is merit in practical calculations when we are all this close to the ground where it all seems either flat or at least geo-centric.
But... the movements of the other planets in our solar system were really strange to model in geo-centric models. In short, each of the other planets should rotate around an imaginary axis to compensate for their changing positions in the sky.
Of course, all this is talk about in the context of our solar system. As for us being the center of the universe, well, the same argument holds for any other point in the universe. So, I think it's less likely than me winning the lottery in the next five minutes :)
In the XVII century, the alternative to heliocentrism was Tycho Brahe’s model: Earth at the centre, the Sun and Moon and the stars revolving around it, and the other planets revolving around the Sun. It was basically equivalent to the heliocentric model with a different coordinate system.
It’s important to understand that astronomers chose it because it really seemed to provide a better explanation given the knowledge and technology at the time.
Tycho Brahe himself noted that his model could be disproved by observing the stellar parallax effect as the Earth orbits the Sun (if the Earth does move, then the stars would look slightly different throughout the year). This is a real effect, but so small that it couldn’t be observed until the XIX century.
There was even more to it. Cosmographers of the time were willing to consider the possibility that the stars were very far away, far enough to make parallax changes undetectable. The main stumbling point was that they assumed the stars would be similar in size to our sun, but based on naked-eye and telescopic measurements of the diameter of the “disk” of the stars (many taken by Brahe and Galileo themselves), any solution that explained the parallax effect would have resulted in enormous stars, and this they couldn’t accept. Eventually the measurements turned out to be an optical artifact.
I read an entire book on this subject, published by a Catholic press. There seems to be an active interest in the Catholic science establishment in rehabilitating some of Galileo’s critics.
> I know it sounds hard to believe, but if you're willing to bite the bullet that "the center of the universe" has no physical meaning, then earth can't be not the center of the universe any more than it can be.
I disagree.
The sentence «"the center of the universe" has no physical meaning» requires that Earth can't be at the center of the universe, because there isn't a center for it to be at.
You're still allowed any or many arbitrary zero-points, but that's only the center of a number line, nothing else.
It's basically a semantic issue but I don't think the negation of an undefined proposition is true, I think it is undefined. (Thankfully the universe does not run in JavaScript, where !undefined is true.)
But, Earth.x = 42 (in some arbitrary coordinate space), if I understand correctly there isn't a sub-light coordinate space in this universe where Earth.x = undefined.
That's not the reason why the centre of the universe is undefined.
By analogy, while spherical coordinates are arbitrary, latitude is defined. Arbitrary, but defined.
But the centre of the Earth has an undefined latitude, and a topological subspace consisting of just the surface of the Earth can't hand-wave past that by pointing out that's just a coordinate singularity that can be safely ignored — there isn't a center of the Earth anywhere in that subspace. If the universe is flat and finite (looping), this problem still exists.
And if the universe is unbounded (infinite), that has a different problem because you can't properly define a median of an infinite set[0], so no center exists.
If it just stops suddenly after a certain amount of space, then we get to have a center, but there's no sign of that.
[0] I think. Infinity is easy to get messed up with.
We may not be able to observed it, and maybe can’t. Just like time slowing down would be imperceptible to the person on the spaceship nearing light speed. It takes the mathematics
Or if I’m lucky enough to have the time to watch the moon move slowly, it feels natural to my senses to say it’s moving across the sky. The moon feels like it’s moving around me. But I can stretch my brain and imagine the reality.
Sometimes math arrives first. We have the new maths (or an problem in current math), and that points to some possibility. Because it’s not observable, ignoring our senses is a requirement to develop that in the model and measurements and experiments. Eventually we are able to observe it.
I’m not familiar with history of astronomy. Would it be the case where the observations that lead to heliocentric thought we nuanced and had to build on more obvious perceptions that things aren’t adding up? Was the wobble of Venus part of that?
And you’re right, old models are useful and remain relevant a lot! The model of time moving linearly will likely always be the most useful model for navigating our daily choices (if we have any at all!)
I disagree, I think the comparison is pretty reasonable.
Your entire experience of the world is defined and limited by the fact that your brain "only processes information in one direction of time" (for lack of better wording). Your personal experience does not necessarily map correctly to the real world. The same is true for both examples.
It's not just a matter of our subjective experience of time, it's a matter of the laws of thermodynamics and entropy. Time moves in one direction is another way of saying entropy always increases. If time could move in the opposite direction, then entropy decreases which breaks our understanding of physics.
It's really interesting to think about how we struggle to express the idea of the future having a causal impact on the past. I reckon this is because our language and our understanding of time are limited.
Our brains like to process events in a linear sequence, from past to present to future, but this view of time might not fully capture how everything in the universe is interconnected. It's possible that our language just can't handle these complex concepts.
So, I don't think anything mentioned in this thread contradicts the idea that "time always moves in one direction" and "entropy always increases".
Right. "Time only moves in one direction" is not saying much more than "our consciousness experience time moving in one direction". The very idea that time "moves" is entirely related to our vantage point. If our perception were not bound to time, then the nature of cause and effect might look completely different.
I don't think the idea that "the future can influence the past" is the same thing as saying that entropy decreases or that time can move in the opposite direction. I think these are different concerns
The "arrow of time" conception of entropy: 1) does not work locally and only works at large enough scales, and; 2) is essentially isomorphic to the concept of time.
So no, it's not at all incompatible with retro-causality. When you think about retro-causality, the idea that time "moves" is completely superfluous. Time is probably not even a real thing.
The direction of causality should also be reversed from what I can tell. Instead of a bullet slowing down as it hits air molecules and pushes them out of the way, the air molecules push on the bullet because the bullet will be sucked into the barrel in the future.
More on topic, I think our existing theories of reality tell us that the future probably affects the past, or at very least, is predetermined. If you know the solution to a differential equation, you know the state at any point in time. There's no going off the rails, so to speak. And if the system is constrained in any dimension (i.e. it's nonholonomic) then the state at any given moment relies on the full trajectory up to that point, as opposed to just the previous state. But you can flip that on its head and say that the future state determines the present trajectory. E.g. to turn a bicycle left, you have to first turn right.
I think it's the same thing. The future energy state of the cartridge is that it's in the chamber, so it gets sucked up. It's problematic though, because the direction of gravity doesn't change.
Just commented about interpreting the Probability Law as sort of "Inverted 2nd. Law of Thermodynamics".
I'll expand here how if the arrow of time actually doesn't exist, the future could change the past without breaking our - current - understanding of physics (tragiclly because we will probably have maybe hundred of years till we change our minds about what are the properties of the universe).
In a range or probabilities of one event, one of the probabilities will always be the one is going to actually happen. Closer to the event to occur the most certain you can be about which one of those, could be the one that will happen.
Here's the catch, you have to change your mind a bit, in our current understanding of physics, the information of the future event which has not happen yet, already exists here in the past for that event.
Now, if you know - and you know - the outcome of an event, you most certainly will be able to choose if you go along that path, or you choose to change the future event to something else. Whoalá, the future changed the past.
Brains of earth continously do this, every second of our entire lives, animal brains do this too, almost all life on Earth has some neurological, physiological, chemical predictive mechanism in place.
An example, you're about to walk across a street, you see a car coming, now your brain "predicts" you'll be hit by that car if you just keep walking, you stop walking to avoid certain death, done, the future changed the past. The information - really close to 100% of probability of death - extracted by the brain from the sheer reality of the universe, allowed you to survive.
And no current understanding of physics got harmed anywhere along the way of the future changing the past.
Yep. Someone else already pointed out the well known counterargument to symmetry below regarding thermodynamics. You typically don't see scrambled eggs become whole again. I think that's pretty hard evidence to overcome.
Granted, I'm not a physicist and I'm sure any physicist working on this totally understands that. Just wanted to point it out.
Negative entropy (also called negentropy) isn't really a well-defined concept. Instead, better to say that biological processes harvest free energy to maintain order in the face of increasing entropy.
If the direction of time is reversed, the eggs become whole again, but your memory of them once being scrambled is reversed, too, so you don't notice anything unusual.
(It's like a rollback of database transaction, where not only the database state, but also the state of everything, including your brain, is getting rolled back)
But is there any evidence of that? Or is it just a thought experiment? I need to read more of the article, but appreciate you giving me some food for thought.
It's a thought experiment, of course. There cannot be any evidence one way or the other, by definition. Any potential evidence is rolled back, too. But then, why are we so sure our current beliefs WRT the arrow ot time are true?
Though there's no hard evidence, but if you think, for example, about the efficiency of evolution - it would be much easier to explain if we assume that the unlimited number of iterations is performed. (This is not the only possible explanation, of course- but this one is overlooked IMO)
I would say that compared with the strange ideas like "multiverse", this one is rather benign :-)
If the future could affect the past, it suggest that then if time reversed, you would notice something unusual right? Kind of like suggesting there is a side effect in your function (consciousness). Kind of like how today, past events can influence the future like we act differently from learning from mistakes.
So the conscious experience of the person at each time would be exactly the same as our experience. They would feel as if they were moving forward in time.
The argument is that thermodynamics is simply a statistical phenomenon. Scrambled eggs are due to proteins denaturing (folding in a random way).
Scrambled eggs do actually unscramble spontaneously if you zoom in far enough. The issue is that the rate of scrambling is much higher than the rate of unscrambling so on the whole, you get scrambled eggs.
The amazing thing is that all chemical processes are actually reversible given enough energy and finesse.
- There seems to be a special direction "down", where things fall by default, because we live in the vicinity of an influential object in space, called Earth
- There seems to be a special direction "forward in time", where things happen by default, because we live in the vicinity of an influential event in time, called Big Bang
If we had stuck to the local Earth context and geocentrism, the objectivity of the "down" direction would remain unquestioned. It's when we started modeling other things outside of Earth, it became clear there's no objective "down" direction, just a more general concept of Gravity.
Carroll's argument is that it's the Big Bang, an extremely low-entropy configuration of the universe, that gives rise to the 2nd Law of Thermodynamics and the resulting emergence of an arrow of time in the forward direction. It's purely a statistical phenomenon at larger scales, and attributable to being "next to an influential event", according to him.
It's difficult to see how such a hypothesis could be tested either experimentally or observationally. Sounds more like metaphysics?
Stars shine until they run out of fuel, and the age of a star - the status of its fuel, the buildup of fusion products - happens as time passes. Life on planets taps into the flow of sunlight from the star (and/or the flow of heat and chemical energy from the a hot planetary core) to generate complex structures in defiance of the regular direction of entropy (not violating conservation of energy, though). So... life reverses the arrow of time?
Well, of course not :) Entropy as direction of time just means that the chaos on the whole increases. So, to create an ordered structure, like a cell organism, the by-product is more chaos around it.
I’d be shocked if that were the case, even only considering the Earth. The oceans and the atmosphere are full of entropy. So is the liquid outer core. And even if the mantle is not quite liquid, and even if the crust is mostly solid, these are huge in terms of volume and mass, much larger than the sliver of dirt we inhabit on top of them. So yeah, I really doubt we (collectively, all human beings) are changing the Earth’s entropy in any meaningful way.
I think that the real question is whether the death of the universe by cool down will happen before the arrow of time is reversed. To me it seems more like it will just slow down and then finally stop.
Or if there ever is a "big crunch" where all black holes crunch together to a critical mass, would there be another big bang and time then run backwards?
The hypothesis I have encountered is that time would reverse when the expansion of the universe peaked and started to collapse back in on itself. The next big bang would start another run of our universe. I'm guessing the randomness in quantum fluctuations would allow this next run to evolve somewhat differently from the one we are experiencing.
I think that one thing to keep in mind is that we are only capable of observing the passage of time along one vector because our perception relies upon entropic biological processes.
We cannot observe in any subset of possible universes where entropy is not present or is working backwards-Ergo those possibilities are wholly out of our direct perception.
That does not mean that causality cannot run in reverse, however, only that we cannot interact with those mechanisms in a way that would preclude our existence or observation.
But could we observe the effects? Can there be particles which have mass and therefore exhibit gravitation but which are subject to reverse entropy? We would observe these for example as an unexplainable increase in gravitational pull on observable matter without an observable source of that gravitation and without a preceding cause.
Are photons themselves stratling this entropic boundary since they travel at the speed of light and within their own reference frame are not subject to the passage of time?
Wouldn't questioning those pre-existing notions be the first step towards constructing such a machine? It sounds silly to dismiss the idea time could go backwards because we don't have any machines that work that way, since that typically how all ideas work before we implement them.
> It's difficult to see how such a hypothesis could be tested either experimentally or observationally. Sounds more like metaphysics?
Sure, but some claims which cannot be tested experimentally or observationally are nonetheless important. For example, the claim “it’s important that scientific hypotheses be tested experimentally or observationally.”
While I agree that not everything in science can be tested experimentally or observationally, arguably this one can:
Models created using both empirical experimentation and logical reasoning match reality much better than those based on "pure logics" (if that even is possible).
At least in France we take as fait accompli that causality is non trivial and that objects are non local at best: either you can consider objects as one despite immense distance between them, or you accept information passed between them in reverse time. Both are hard to swallow.
> Life on planets taps into the flow of sunlight from the star (and/or the flow of heat and chemical energy from the a hot planetary core) to generate complex structures in defiance of the regular direction of entropy
It doesn't defy the direction of entropy. Frankly, I'm not sure why you have that notion? Entropy is a measure of system's state of equilibrium. Moving energy from a concentrated source, and distributing it more equally (across life forms and other complex structures), is following the direction of entropy, as is it makes energy more equalized, in contrast to the former state where energy levels are more unequal between highly concentrated areas (like stars, the Big Bang), and areas with less energy.
Entropy only increases on average. You can decrease it locally, for example, making steel from iron ore. You generate heat, so you still get a net increase, but you could easily redefine your boundary to only include the local decrease in entropy (the steel from ore).
Yes, but like you said, that requires re-drawing your boundaries. It doesn't really defy the direction of entropy, it only appears that way from having changed scope.
The regular arrow of time from the human perspective, "leaks" changes into the future. The future is constantly being changed by the past.
You can measure those changes by many ways, the 2nd. law of thermodynamics is everywhere just to make sure you see this happening across everything.
So, probably there are other non-discovered underlying mechanisms in the reality that are already signaling changes from the future "leaking" into the past, changing the past right infront of us, without us noticing it.
A probably omnipresent mechanism for observing the future changing the past, valid in the whole cone of light visible to us, is the probability law.
If you have 10 millions of possible events in a probability, one of them is the exact thing it will happen in the future, hence the information of what happens in the future is right here, existing in the past.
Yeah, you can say how would the nature could use this information without powerful processors predicting branches trillions of times per second on Earth right now?
Well, the brain is a pattern predictor, quite several parts of the brain are firmly attached to the physics of the universe, biochemically but what if the pattern prediction mechanisms in the brain are actually an adaptation of the evolution, just like wings to fly, but with those mechanisms the brain uses probability to "see" information from the future, and here in the "present", it changes the past (from the perspective of the future created originally from the past), if the brain "chooses now" to do something different that what originally created the future it "saw" by analizing patterns, essentially evaluating probabilities.
So the Probability Law would be a kind of Inverted 2nd. Law of Thermodynamics.
It would work perfectly as law of the universe: from the future to the past, the revered time of arrow, one single event created "a" future, but from the regular arrow of time, there would a range of probable future outcomes which you cannot precisely say it has "1" (100%) probability of ocurring, right to exact moment till the future becomes the present.
And it was right there all the time, something obvious infront of everybody in the world, like electricity (which was suspected by many across thousands of years, but just "discovered" recently).
You can, but that inevitably leads to far more Boltzman brains than things like the universe, and that's disastrous because then you should expect to be a Boltzman brain yourself, but they're configured randomly so if you are a Boltzman brain you can't trust any belief you have about reality including the maths that says you should be a Boltzman brain.
It's basically a softer version of Russell's paradox but for cognition and reality.
Hard to summarize, but it's well worth anyone interested in this topic. There's a good bit where he ties the sleeping beauty thought experiment with Boltzmann Brains and consciousness; it blew my mind trying to understand the whole thing.
The comparison is bad all around. Geocentrism actually had decent reasoning and was not a superstition. It's just we couldn't see the parallax with then-current instruments. As soon as instruments allowed, humanity changed rather quickly.
Time moving in one direction actually has decent reasoning and is not a superstition. It's just we can't detect time moving backwards with now-current instruments. As soon as instruments allow, humanity will change rather quickly.
The problem with the comparison is what it's used to imply. The popular understanding* is that scientists believed in religious dogma, and that led them to 'unscientific' geocentrism and believing that time has only one direction. It's a backhanded accusation of superstition, and that's unfair towards both current scientists and past scientists.
(On a personal note, I'm actually sympathetic to the article's retrocasual proposition. I suspect reality is non-local and TSVF etc. naturally tend towards non-locality.)
* This is Vice, of course they use the popular understanding and not something more sophisticated.
It seems to me that the popular understanding is influenced by grossly misleading 20th century anti-religious propaganda. The geocentric model is not something the Catholic Church plucked out of the bible; they got it from Ptolemy and other 'heathen' classical thinkers, whom the Catholic Church considered meritorious despite not being Christians. Sure, they then found some biblical citations to back themselves up in this, but the idea was never their own in the first place.
> Slow down. Assuming that time moves in one direction is not comparable to geocentrism.
Why not?
The "arrow of time" almost always requires thermodynamic arguments. And that requires a concentration of "low entropy" to move toward "high entropy". Which, by definition, are "boundary conditions" and not a fundamental part of your physical rules.
If, for example, your universe is entropically uniform, is there an "arrow of time"? And, even if there were, could you detect it?
However, I would like to point out that it's not like we haven't had this kind of issue before. The Bohr-Einstein debates were a good example. Einstein favored a "fields" interpretation of quantum mechanics. Unfortunately, Einstein's interpretation predicted that atomic states wouldn't decay, and that was clearly, obviously wrong, and Bohr very much hammered on that.
Except that Einstein wasn't "clearly, obviously wrong." As you increasingly isolate excited atoms, their atomic states take longer and longer to decay. The problem was that the experiments of the day couldn't create these kinds of singular quantum state systems--they were stuck with systems that were contaminated with lots of thermodynamic interactions.
We may be seeing something similar here. We are just starting to be able to put together the experiments that can probe things like Bell's Inequality. As we isolate these systems, we may find that the systems were contaminated with statistical time and that we get different results when we can isolate them.
> If, for example, your universe is entropically uniform, is there an "arrow of time"?
No. For a system at thermodynamics equilibrium entropy is constant, neither increasing nor decreasing. So there is no arrow of time, no sense in which one direction is "the future" and the other "the past".
If a universe were entropically uniform, wouldn't the arrow of time definitely be negative? Wouldn't any random evolution result in a lessening of entropy by definition?
> If, for example, your universe is entropically uniform, is there an "arrow of time"? And, even if there were, could you detect it?
Would we have fluctuations in that state? In which directions they would... Progress?
Isn't what you describe an anomaly like black hole or division by zero, where we cannot understand what actually happens because normal laws break because they are unsolvable with current models?
If time is a true dimension rather than just something we model as a dimension, it's not unreasonable to think that outcomes in the present could be influenced by constraints that exist in the future - if the "universe" function must be valid according to some constraints at all points in the time dimension, "past" states that lead to invalid future states will never occur.
The idea of invalid universe states is of course purely fun conjecture, but this same concept also maps to probable vs improbable universe states as well. If a future state is improbable (in the sense of a Bayesian prior according to some underlying distribution of energy in the universe) that might cause the universe to evolve in a way that seems improbable at the moment by moment level, but is actually the most probable sequence of events when integrated over the entire duration of the universe.
Time could move backwards if we lived in a time symmetric universe. We don't. Maybe if you flipped the charge and handedness of the entire universe you could also reverse time, but that's yet to be tested.
The idea doesn't seem so different from matter being the default (vs. antimatter), relative speeds much closer to zero than to the speed of light being what's commonly observable etc.
I think the actual assumption is that we are currently seeing just one direction of the arrow of time, but if there is no arrow of time, maybe we are already seeing the future and not realizing it is the future.
I commented further in this line of though in another comments, about a probable (ironically), "Inverted 2nd. Law of Thermodynamics" of sorts, which it would be basically just the Law of Probability, interpreted from the point of view of not having an actual arrow of time and the fact that we have - all the time, again ironically - the information of what happens in the future (the one probability in the range which ends being the right one, actually ocurring).
Yeah, I know it would be another Law, and the universe would upside down once again for us the poor meatbags, but we were already in this position several times, discovering the electricity, quantum mechanics, relativiy, you name it.
454 comments
[ 1.1 ms ] story [ 419 ms ] threadIt's the extrapolation of models that we've created in the present, but those models are only our best guess at the truth. They may be revised in the future or simply not hold for the past.
This seems.....paradoxical...ironic?
> That we are only able to perceive reality by proxy doesn't mean that it doesn't exist, though....
True, but potentially misleading/misinformative.
> ...it just means that...
Are you sure? Are you referring to the territory here, or the map?
>...we have to get used to using maps, while remembering that they can be flawed.
We've been using maps since the dawn of man, and a lot of people have substantial, abstract knowledge that this is what we're doing....and yet, look at the mess all around us, and the conversations we have about that mess (though: during these conversations, are the participants discussing the map, or the territory: a) in fact? b) in perception?).
Perception and reality are not in fact the same thing.
It was factual that the earth was 6000 years old, until it wasn't.
This is the opposite of the example you seem to think it is. The Earth has always had the same actual date of origin. If it is not factual now that the Earth is 6,000 years old, then it wasn't before either. The whole argument here is that people's perceptions and reality can in fact be different.
Maybe, but I'm asking: can you show that peoples' perceptions match/differ from reality, without relying on perceptions being factual/reliable?
If not, then how do you know that reality is fixed?
What actually happened is unprovable without some layer of trust once the event leaves the affected. For example, I ate a grapefruit for breakfast. That is a fact. However, I have tossed the peel away and I am communicating that I ate it with a stranger over the internet. For all you know, I could have eaten cookie crisp. If you and enough people get together and collectively believe that I ate cookie crisp, the public belief will be that I ate cookie crisp. However, that does not change the fact that I ate a grapefruit.
So sure that regardless of what evidence you are presented, you'd be certain that you ate a grapefruit. Even if:
- I showed you videoproof that you were eating a sandwich for breakfast
- we had all of your family say they were having breakfast with you and saw you eating a sandwich
- a doctor came and said "I analyzed your stool and found no evidence of grapefruit"
- we had a message, cryptographically signed by a key you generated/controlled, that said "man this sandwich is delicious"
Even with any amount of evidence to the contrary, you'd still believe that you ate a grapefruit?
If not, then are you sure that it's fact that you ate a grapefruit, or it's just that all current evidence points to you eating a grapefruit?
Either
-my perception of reality is inherently opposed to objective reality
or
-the world, for some reason, is gaslighting me into thinking I ate a sandwich and the objective reality is that I ate a grapefruit.
See, my problem with this "philosophy" that objective reality does not exist is that it enables abusers. Have you ever seen the movie Gaslight? Its a classic. This poor woman lives with an abuser...someone who is committed to making her think that she is crazy. He contradicts everything she does and says, sets up evidence to objectively prove that she only imagined herself doing it, and keeps her under his thumb through those means. In the end of the movie, its revealed that none of the evidence is real and that she is sane. To combat against these types of people, its important to be sure of your own reality and only change if evidence is overwhelmingly pointed in the opposite direction. Even then, question these changes in belief heavily. Otherwise, you will believe just about anything anyone says.
If you were not there and didn’t not commit the crime, is that past to which used to determine your conviction factual?
Whether later you are proven not guilty, the past didn’t change, but rather our perception of it.
I'm not enough of a skeptic to say "don't trust the models of the past"; memory turns out to be a pretty good model. So does carbon dating.
But the reason you say "you were not there and did not commit the crime" is because you don't remember being there. Maybe you even remember being elsewhere. But that doesn't mean it's true, memory is fallible.
You might say that you even have photos of yourself somewhere else at the time. But if there were photos of you at the crime scene, would that change what the past was? Maybe your memory is shoddy, or maybe the photos are fake.
Think about big systems. The moon is a ginormous rock that's so big it is visible from thousands of km away, but it just hangs in the sky because it's moving so fast it can cheat gravity, but we can barely even see it move. Or think about how a star can somehow explode because it starts running out of fuel (and our sun is just yellow hot - you can do that with a blow torch, but it's powered by a nuclear explosion - I guess it's got quite a bit of surface area?). And little things are even weirder, consider how fast the proteins in your cells bounce around. Then there's quantum - our gut intuition is so out of its comfort zone it's basically meaningless.
powered by a nuclear explosion
Not quite accurate. The nuclear fusion going on inside the sun's core is not an explosion. In a nuclear explosion, a significant fraction of the fuel in a given area is consumed in an instant. The sun's core on the other hand only fuses its fuel extremely slowly. Pound for pound, the sun's core generates less heat energy than mammalian muscle tissue. It's just that there's so much of it that the heat energy is extremely well insulated.
Incorrect. The out of atmosphere color temperature of Sol is ~5900K. The average color temperature of the Milky Way is 4700-5000K.
https://www.news.pitt.edu/milkywaycolor
I applaud You.
https://en.m.wikipedia.org/wiki/Singularity_Sky
To make this no longer be (at some point in the future) the state of affairs, how could it be done (make it "in fact")?
"Why not?" seems like a decent first attack to the problem - why are physicists (or, scientists in general) so bad at philosophy? For one, I would nominate the "When you have a powerful hammer, everything looks like a nail" psychological phenomenon, as one plausible part of the puzzle.
If so, does that mean that the big bang could actually be the end of the universe and we're just experiencing time in "reverse" toward an initial starting state that we perceive as the future?
https://i.pinimg.com/originals/27/d7/8c/27d78c9c3ee93c13eda4...
Holographic universe is that the physics and information in a 3+1D space time could be encoded into a 2+1D universe (with it's own physics).
https://www.discovermagazine.com/the-sciences/from-here-to-e...
https://i.ebayimg.com/images/g/xH8AAOSwryZi3Ef0/s-l1600.jpg
https://en.wikipedia.org/wiki/Tralfamadore#Slaughterhouse-Fi...
It's convenient to model our movement through space-time as occurring at the speed of light. Thus, the faster we move in space, the slower we move in time all the while the length of our space-time velocity vector is invariably c. We can then imagine 1 second of time being interchangeable with 299,792,458m.
https://en.wikipedia.org/wiki/The_Quincunx_of_Time
Also, the concept of causality itself is a kind of underlying theme in Hannu Rajaniemi's "The Causal Angel" (2014) (3rd of a series).
In very informal terms, anywhere where there is very low entropy (higher order), any direction away from that will likely (to the point of certainty) be in a direction of higher entropy (lower order).
For instance, if you have a jar of red & blue marble, with high order (such as perfect alternating layers of red vs blue marbles) then any disturbances (such as shaking the jar, reaching in and moving a handful, …) will almost certainly reduce order.
And no practical amount of shaking the jar will ever return the marbles to a high order state again.
Even though any close up video of the marbles being jostled will reveal the same physical properties and behavior for the marbles, whether played forward or backward.
So at the individual marble level, laws are symmetric.
But at the jar of marbles level, one direction of time looks very different than the other.
We, and the particles that make us, and our environment, are the marbles whose configuration is more disordered the further in time we get from the Big Bang.
So we perceive the time direction away from the Big Bang as the future, toward the Big Bang as the past.
And the statistical “force” of increasing entropy provides the useful energy we use to survive, learn, create useful islands of order, in the greater sea of increasing disorder.
This can't be true. Take the case where there's only 2 marbles, it's likely that at some point that shaking them will return them to the original state. For higher numbers of marbles the probability becomes lower and lower, but is never 0.
(0.00..0..1 = 0 just as 0.99 repeating equals 1)
This sounds like a rather bold statement to make, as long as we're already speaking so metaphysically.
[0] https://stats.stackexchange.com/questions/142730/px-x-0-when...
See: https://en.wikipedia.org/wiki/Continuum_hypothesis
Again, I'm not a physicist, but I think it's telling that the validity of continuum mechanics [0] depends on a model and multiple assumptions. I have no trouble agreeing with your original statement, "with enough marbles, the discrete distribution behaves like a continuous distribution," when speaking mathematically, but mathematics by its nature is an idealized model of the world - I'm not willing to accept that it's objectively representative of physical reality. The discussion we're having here is one of metaphysics, so it feels a bit like the height of hubris to use mathematics as the tool for describing objective reality, because metaphysically, we cannot say that mathematics is anything other than a tool we've constructed for approximating the model of the world as we understand it. Considering the subject of this post is about retrocausality, we're already throwing out some pretty wild ideas, so I think it's a bit hubristic to dismiss them by citing a branch of mathematics that assumes the existence of countably infinite sets [1].
[0] https://en.wikipedia.org/wiki/Continuum_mechanics#Validity
[1] https://en.wikipedia.org/wiki/Constructivism_(philosophy_of_...
Hence the disclaimer. I just think this stuff is fascinating. If you're interested, this is the article that originally got me thinking about these ideas as they relate to the flow of time: "Does Time Really Flow? New Clues Come From a Century-Old Approach to Math" [0]. It's effectively an appeal to intuitionist mathematics and a rejection of constructivism, where - simplified - every particle since the big bang can be assigned some "number" that describes its position on its world line, with a precision that is finite, but always increasing - and it's this increase in precision from which emerges the "flow" of time. If you ctrl+f the article for "continuum," you'll see some better constructed arguments for what I'm trying to argue, e.g.:
> Moreover, the continuum can’t be cleanly divided into two parts consisting of all numbers less than ½ and all those greater than or equal to ½. “If you try to cut the continuum in half, this number x is going to stick to the knife, and it won’t be on the left or on the right,” said Posy. “The continuum is viscous; it’s sticky.”
The impression I'm left with is that the difference between constructivist vs. intuitionist mathematics (which rejects the law of the excluded middle) has some parallels to the difference between eternalism (there is a past, present and future) vs. presentism (there is only the present).
As a layman, I just can't help but notice the same patterns come up again and again when looking at unresolved problems between classical and quantum mechanics, namely those that lie at the boundary between the continuous and discrete. FWIW, I asked ChatGPT for some unresolved mathematical problems that might relate to this, and it came up with: The Continuum Hypothesis, The Axiom of Choice, and The Riemann Hypothesis, all of which it admitted are possibly impossible to prove because they're effectively unfalsifiable. (I also showed it this entire thread, and it agreed with your critique of my arguments, but also that every argument in the thread is unfalsifiable - and then it pointed me to the Boltzmann Brain paradox).
[0] https://www.quantamagazine.org/does-time-really-flow-new-clu...
Mathematics still apply.
[0] https://en.wikipedia.org/wiki/Zeno%27s_paradoxes#In_modern_m...
[1] https://en.wikipedia.org/wiki/Philosophy_of_space_and_time#D...
Even if the point probability is 0 or approaching zero very fast, some event occurs with probability 1.
The probability that life would evolve on a blue planet that its anthropomorphic inhabitants will come to call Gaia or Earth, has as a star Sol, in this corner of the Milky Way, in this particular local group and so on is zero even if we limit ourselves to just the observable universe.
At the same time the probability that life will exist at some planet at some solar system at some galaxy at some local group and so on, is practically 1.
That is to say, depending on how you categorise and count said marbles, the reordering may occur.
While any individual marble will not be at its place with P=1. You can still end up in a situation where the marbles are ordered in layers.
The whole thing regarding entropy is concerned with a closed system. You can very much exchange energy to decrease entropy, but said exchange is a) leaky, and b) implies that the system is not isolated.
This was then used again when mentioning earth to argue that depending on the definition of "order" here:
> And no practical amount of shaking the jar will ever return the marbles to a high order state again.
It is entirely possible to reach a state of higher order if you don't require that individual marbles don't hold the same arrangement relative to adjacent marbles, meaning that any permutation of marbles with identical color is acceptable.
This happens because the event you are asking for is a very large subset.
This whole thread is silly, The 2nd law is about probabilities which are asymptotically 0, so small in practice that we could never do experiments to frequentist probability empirically, using "jars of marbles" with more than 100 marbles", let alone trillions of trillions of particles.
I realize that programmers are not always good scientists. Yet some claims are absurd in ways that I now believe this phenomenon necessitates rigorous study.
[0] https://stats.stackexchange.com/a/273398
IIUC my professor right the probability is non zero but is practically impossible for a large number of incompressible spheres.
Exactly. It doesn’t take a very large jar to make a return to an original state practically impossible. But even for two marbles, shaking them to return them to their original locations costs a fair amount of organized energy.
And that is organized chemical energy in your muscles, which you are dissipating as disorganized heat energy due to your efforts, increasing the total disorganization.
And the marbles are microscopically wearing down, shedding compounds. The jar is also wearing down. Both becoming less organized.
So even with two marbles, overall entropy continues increasing.
We can locally reverse entropy, only at the cost of actually increasing entropy in total.
- Organizing your day takes effort and uses up useful organized energy.
- Computation uses up useful organized energy.
- Your cells, maintaining their metabolism, uses up useful organized energy.
No matter what we do, entropy still increases.
Everything we do takes advantage of the higher to lower entropy gradient.
We get relatively organized photons from the sun, a percentage get stored in wood of trees, so we can burn that for heat which can drive an engine or generate electricity, with the end result is doing some useful work.
And we don’t actually lose any energy, due to conservation of energy.
But we have now lost USABLE energy, because all our captured energy is now heat diffusely spreading out from our engine into the atmosphere where it becomes uncontrolled DISORGANIZED and therefore no longer usable.
So clear causes tend to occur in past of clear effects.
For large objects.
But again, if you watch videos of individual marbles bouncing around, forward or backward, you see just as clear chains of cause and effect in either direction.
Marbles in a jar are not arranged in a neat spacial grid, but in all kinds of configurations.
The chance of recovering any near perfect starting symmetry, depending on the size of a jar, might take decades or millions, or more years.
In the meantime, all that energy being used to shake the jar is generating huge amounts of heat entropy.
It is possible that that the original expansion, inflation, and even dark energy are also driven by thermodynamics, but we just don’t know that.
Im not saying you're wrong, but then there's Poincare's recurrence theorem. Entropy is funky. (Certainly not practical amounts anyway)
I often find them insightful, especially if I am reviewing them again years later.
– The laws of physics are essentially time-symmetric, and they have no concept of causation or of a preferred direction of time. In principle, the future causes the past as much or as little as the past causes the future. Physics effectively only says they have to be consistent with each other, as related by the laws of physics.
– The apparent directionality of time that we perceive is suspected to be tied to the entropy gradient we are on. See the “past hypothesis” for example [0].
> Does this essentially mean that all states in time already exist and our consciousness is just traversing this 4D space in one direction on the time axis?
– I would say that all moments in time are equally real, including our consciousness at any given moment. There is no actual flow or “travelling”. The flow we perceive is merely an illusion caused by the fact that we only remember the past and not the future (which again may just be a consequence of the entropy gradient we are on). This is known as the “block universe”, or as “eternalism” [1]. The opposing view that only the current moment is real, and that the future differs from the past in its “realness”, is known as “presentism”.
– Note that any notion of “travelling” through time implies that you can draw a 2D diagram of where in time you are at each point in time, or which point in time is “real” at which point in time (in the sense that a moment in time isn’t real until time reaches that moment, but after that it is real and cannot be made unreal again), thus implying two dimensions of time. That doesn’t make any sense, and thus my personal conclusion is that the “presentism” view is nonsensical.
[0] https://en.wikipedia.org/wiki/Past_hypothesis
[1] https://en.wikipedia.org/wiki/Eternalism_(philosophy_of_time...
Usually the fundamental laws are regarded as time symmetric already.
What does this mean: > Instead, retrocausal models suggest that there is a mechanism that allows circumstances in the future to correlate with past states.
Surely future states inevitably correlate with past states?
Perhaps it all makes sense but that article doesn't make a compelling case.
This is just one example I found but I think there might be another experiment from a few years ago that was getting some attention at the time (although I might be confusing it with a theory paper):
https://www.nature.com/articles/s41598-023-29970-6
There are probably better overview articles on retrocausality.
https://www.newscientist.com/article/mg23731652-800-quantum-...
https://aeon.co/essays/can-retrocausality-solve-the-puzzle-o...
https://phys.org/news/2017-07-physicists-retrocausal-quantum...
I'd have to read through all these more thoroughly but I wonder if there's some "time locality" property in these models?
He means to correlate through effects going the future -> past direction...
What can it mean to have an effect propagating into the past? Surely our usual definition of time is simply a series of events. If so then it always points in one direction for the entity sitting at the leading edge, the current event is always succeeded by the next event.
All I have to go on is the article, perhaps the source material makes more sense.
Well, in addition to time reversal, you also have to mirror the universe and replace all particles with their anti-particles.
The funny line there is at this point in time. The whole article is about how the future influences the past so… at some point in time retrocauslity will be the same thing?
If in my physics theory I redefine that past=future and future=past then I have a physics theory where the future influences the past, and very strongly so.
Or, I guess the point is, maybe it’s the same thing.
Calvin believed in pre-destination (your fate and every decision you make is decided before you exist) on the grounds that, because God exists and is omnipotent, what you are doing must therefore be what God wants to happen, both good and bad. After all, God is omnipotent, so there you go.
Today's Calvinists just replace God-driven destiny with nature-driven destiny, but the underlying tautology (X exists, therefore X was always destined to exist, as proven by the fact that it exists at all) remains the same. In fact, it's an arguably more ignorant version of Calvinism, because it requires that one completely dismisses any knowledge they have of probability theory. So it's the "smarter" Calvinism that requires you be ignorant of 20th century mathematical advances.
Hate that crap. The only people I hear talking about it are silicon valley utopians, which is probably the other reason I hate it.
No to pick too many nits, but I think it is well established that knowledge of formal sciences (i.e. mathematics) does not impart knowledge about natural sciences (i.e. physics). While maths a useful tool, there are no established rules of inference for reality, and without rules of inference you can't really make claims on infinite sets.
Natural sciences allow us to find mathematical constructs that make good predictions within specific constraints or that have not yet been falsified, just because something is true in probability theory does not make it true in reality.
I entirely fail to see how probability theory means it's impossible for the universe to be deterministic.
I dunno, seems like a "God of the gaps" thing - we can speculate on meta-meta-universes endlessly. Including one where my decision to have a ham sandwich disturbs the state of a yet higher dimension that sets the starting parameters of your higher dimension and once again I have free will.
https://arxiv.org/abs/1306.0159
And yes, provability is a major problem with all these kinds of theories. We don't have a parallel universe handy as a control, and just saying "I am not going to have a ham sandwich tomorrow" isn't a viable experiment.
*: On "utilize". A central debate (the central debate?) seems to be what sort of "state access mechanism" this maps to in our lexicon: "{reading|writing} {global|local|shared} {bandwidth|memory}"
Technically, casualty required that anyway. My understanding that it's infinity in space, not time that matters here. i.e. predicting your decision to have a ham sandwich may require predicting the entire universe and since we're part of the universe and can't look from 'outside' that decision would be unpredictable from inside the universe.
>And yes, provability is a major problem with all these kinds of theories.
I think showing that quantum effects are negligible for human brains would do, at least regarding your decision to have a ham sandwich?
So yes, the prediction of the decision to have a ham sandwich tomorrow, for any given person is now, by the state of the art of applied mathematics and information science, a relative doable - if not plain easy - feat.
And according to some hypothesis, the brain could be doing this exactly kind of predictions, even more better than LLMs, with more accuracy/speed using way less energy.
Sure, the LLM may be able to guess by reasoning (e.g. 'He always eats ham sandwiches for breakfast and he probably wouldn't break his routine'), the same way we could guess at another person's behaviour, but we're talking about reducing the brain into a deterministic input/output machine, which is a far larger ask.
Now if you said 'doable' that may be right in the long term, but 'easy'? Absolutely not. There's no current way to feed 'me' or 'you' into an equivalent LLM. The human brain has more axons then there are stars in the galaxy and we are nowhere close to even mapping these connections.
>The brain could be doing this exactly kind of predictions, even more better than LLMs, with more accuracy/speed using way less energy.
That's definitely an option. The fact that many of the brain's operations could be done by LLMs is a strike against the original thesis.
In addition, in the many-worlds view of quantum mechanics, we don’t follow just a single sequence of events, but all physically possible sequences of events, where the points where sequences branch off each other can correspond to different decisions we “freely” took. Meaning, when we make a decision, all applicable options of choice will become actual reality.
Compatibilism is a fancy way of saying "free will so much does not exist that what determists call free will isn't even a valid definition to use as a starting point for investigating an answer." It's not an answer to the question, it's a denial of it.
Another, simpler interpretation of Compatibilism is "if free will doesn't exist, then believing it exists or not has 0 effect on anything, because our beliefs are predetermined, and so at human scales the answers Yes and No are equivalent in all observable ways".
There also isn't any free will, because there isn't actually any agent who could have it. Actions we perceive as volitional actually arise in the brain up to 7s before we "choose" them. The sense of a "me" is a post hoc add-on that claims credit for everything, in order to unite the disparate phenomena that comprise the sense of self.
There isn't actually any "me," and recognizing this is what the word "enlightenment" refers to.
The comment that superdeterminism requires a higher-order determinism, which itself requires a yet-higher-order determinism... I think you're confusing it with a causal mindset. If the universe is effectively a recording, why does it need any ultimate cause? Causal thinking would only make sense from a perspective within that recording.
Of course we want to know "why is any of this here?" But what if the ultimate question doesn't actually have an answer?
The compilation of each possible Play in an Extensive Normal Form Game into a cellular automata can constitute a refutation by counterexample of your claim. It satisfies the agent condition through congruence with the technical language defining the concept of agent in artificial intelligence literature as it relates to agents in multi-agent multi-step decision theory problems. The condition of non-deterministic policies is found and shown to be optimal by Nash's justification for an mixed strategy equilibrium. The underlying mathematics that leads there is proven via Russel and there exists various proofs of the desiderata of probability from others which can begin atop that. Furthermore by compiling the formal system to get a physical system we create the ability for a logical analogy between the formal system and the physical system through Aristotle's analogical congruence concepts. We can count the cell configurations and we can count the transitional structure, but this is mostly a formality since we know through the definition of the compilation that they must agree. As far as I can tell at every single step in the laddering up there are proofs from the basics of logic to the mathematics to the use of probability to the justification through utility theory and even to the computational universality necessary to create the physical embedding of the agent in our reality.
The prior conception of guess appears laughable posterior to computation and comparison with evidence, but is just science prior and seeing it is wrong is hindsight bias posterior. It might sound laughable, but it is actually the case that it is not a laughing matter [1]. In like manner, but slightly different and perilously close to being anti-scientific is that you don't know until the observation whether guesses would go one way or another.
[1]: https://www.youtube.com/watch?v=EYPapE-3FRw
There is this story about a village of blind men and elephants. You are like a blind man from that village, saying that the elephant must be abstract because you felt a footprint of the elephant. Try playing with an elephant carving. It predicts footprints when you press it it into the ground. You can totally guess before you touch the elephant on the basis of the carving. The decision to focus on the untestable is a commitment to a hindsight fallacy which experimental investigation would likely refute.
H0: Free will predicts in advance of a decision problem that when a decision problem is resolved you cannot always predict the result.
H1: A lack of free will predicts of a decision problem that when a decision problem is resolved you can always have predicted the result in advance of the result, because there was only one possible resolution.
Complete Refutation of H1: The existence of halting problems. A self-reference in a decision problem refutes H1, because the self-reference
Additional strong evidence against H1: All the most successful epistemological frameworks suppose a superposition over positions which on attaining information about the next position resolves, not to a position, but to a new superposition. For example science does this. It believes we don't know for certain the theories, but we conjecture guesses and use observations to test them.
Implication of failure of H1 and the failure to refute H0: There exists a self-reference, a sort of self-concept, which prevents the resolution of a prediction prior to the resolution. Self-reference exists as a thing which must be computed.
Okay. So now we pick back up in the mathematics that deals with self-reference in game theory. In it we find equilibrium concepts which are defined with respect to self-reference and proven relative to self-reference considerations. These proofs show that the solution structure contingent on self-reference is non-deterministic.
Implication: Not only does self-reference exist, but the consequences of self-reference is the use of self-reference to refute self-referential prediction or to support self-referential prediction on the basis of utility of doing so or not doing so.
So now we know a self-reference must exist, we also know it predicts a refutation in some cases of the ability to predict it. We can also see that if the self-reference didn't exist, it would imply that there was no structure which wasn't computationally irreducible like self-reference structures are.
H3: We will see everything is predictable from the information contexts available, because agents don't exist. Example predictions: that all physics will be determinable like the position of a planet is determinable.
H4: We will that some things are not predictable, because of the existence of illusions that prevent resolution and which contain a self-reference consideration.
What we actually observe is H4. We observe H4 in at least one case, so we can't infer from H3 that we can reject H4, because H4 already rejects the safety of H3.
Let me give an example: Some deer in Africa don't see orange. Tigers, to us, are orange. To the deer they are green. The tiger color is decided by a self-reference consideration with the deer perceptual system. The deer is not going to be able to predict the future state of all tiger like we could predict the planets, because the deer is caught in a superposition with respect to a tiger's presence. When it observes a tiger, this looks the same as observing a bush. Therefore, even if it sees a bush, it can't predict that it can always model the consequence of a bush. Therefore, if we see a planet, it is incorrect to assume we can always predict the consequences of seeing a planet.
So now you can understand, if my other comment didn't click, why appeals to illusion are actually evidence for self-reference, not evidence against it. So feel free to read that comment again to see if it now clicks.
To the second question, yes. It's beyond comprehension and wondrous. It's maximum novelty and total absurdity.
An anti-enlightenment koan could be: The student came to the master and asked, “Why are tigers green?” The master responded, “The deer they are hunting can’t see orange.” The student then asked, “It is not therefore it is? How mysterious and inscrutable your answers!” But from that moment onwards the master was de-enlightened.
Another angle on it would be showing that the universe has multiple possible levels of detail - that objects behave like newtonian point masses most of the time, that digestion is replaced by a simple hunger meter when nobody's paying attention.
From this direction, time's main function is compressing "now" so there's more space for something else later.
I'd be willing to believe that everyone has a god-given amount of universe rendering time that can be allocated in different ways, and that other people's attention stacks with it in a complex, layered way.
It's the same as "If a tree falls in the forest and nobody is around to hear it, does it make a sound?"
But then again, that information has to be stored somewhere right?
Like, if a tree falls in the woods and nobody is around, sure you can say it isn't being perceived so it won't be "rendered" but the moment someone walks in the forest and sees that fallen tree, it would need to be rendered from some information about the fall and information of how it looked before the fall. That information would have to be sitting somewhere in limbo waiting to be rendered. So why not just actually let it sit IN the rendered "realm" and now you have one place for data to live in. You save on data transfer fees too.
As a collection of probabilities stored as a wave.
If a bank account has a 50% probability earning a penny every second, the bank doesn't need to store all of the intermediate values for every "clock tick", but instead calculate how much has accumulated since the last time someone checked the account and store that value with a timestamp.
Not existing is the cheapest.
Then, broad strokes, location and orientation
Then pieces, level of decay
etc,
and moving between the layers is you spending your attention budget to force the universe to do more work.
Coupling this thought with the simulation theory, it makes me wonder how the simulation would respond to increasing entropy over a larger volume than just our local system. That is, if we send a bunch of biological/artificial agents in all directions throughout the cosmos and let them wreak havoc, would it crash the simulation? Or what if we just smash a bunch of asteroids out of their stable orbits and let their disruption cascade throughout the system? Or maybe we've already messed everything up by broadcasting highly entropic radio waves throughout a spherical volume with a radius of ~100 light years?
But there's a difference between "screaming into the void", like broadcasting radio waves, that presumably have 0 effects, and other things.
I have seen creationists in web forums trot this exact argument out (only the creator was God of course).
https://www.scientificamerican.com/article/the-universe-is-n...
Beware, getting from one to two is already a growing number!
Side note: does anyone remember when Vice was “fringe” in its content? I mean, ten or so years ago…
I would argue that the idea instead is to try to make predictions for future experiments. In the case of quantum gravity, especially string theory, these might be thought experiments (what happens if you fall into a black hole), technically infeasible experiments (what would a particle accelerator with the size of the solar system produce), or even completely hypothetical (what if the universe would have eleven macroscopic dimensions) but that does not change the underlying mindset.
When it comes to the interpretation of quantum mechanics there is just nothing left to explain. There is no experiment that decides between different interpretations, so that is it as far as most physicists are concerned.
The ideas in the linked article suffer from the same fate: there does not seem to be even a hypothetical way to test them, and the topic is therefore considered one of philosophy more than physics.
Linguistics: retrocausality -- is going into my 2023 lexicon...
http://gurdjiefffourthway.org/pdf/GURDJIEFF%20AND%20TIME.pdf
https://metallicman.com/detailed-breakdown-of-consciousness-...
Slow down. Assuming that time moves in one direction is not comparable to geocentrism.
Does that make more sense to you?
Have we observed reflected gravitational waves? In reverse-time, where would they originate from if they presumably rippled out into space and didn't collide with anything in forward-time?
Tenet has nothing to do with this- I'm just explaining it as it was covered in my many physics classes that covered the nature of the arrow of time (https://en.wikipedia.org/wiki/Arrow_of_time) and how I interpret it in terms of what seems most likely/least unlikely.
Let's consider something else - imagine an accretion disk of space dust slowly pulling itself together to form a planet. Play that in reverse, and you have the a planet slowly coming apart piece by piece. Imagine reversing the impact that created the moon. The moon comes apart piece by piece, creating an accretion disk around the earth, which then all moves and hits one area of the earth, and there several parts of it (and part of the earth itself) move together to form a separate planet, which then launches itself from the earths surface into space, flies around the sun a few times, and then slowly breaks apart piece by piece into another accretion disk.
F = ma
F = m dv/dt
u = -t dv/dt = -dv/du
- F = m dv/du
If you stop there it looks like you're right, but you also must change the definition of velocity to account for the new time.
v = dx/dt = -dx/du
+F = m dx/du
So the direction of gravity (the force F) stays the same when you flip time. I can explain that without the math by pointing out that if you took a video of a ball being thrown up and caught and played it in reverse, it would still depict a ball being thrown up and caught.
That's amazing, thanks. The portion where you caught the ball in forward time is equivalent to throwing the ball in reverse time.
I need to rewatch Tenet some day
> unbelievable (but still physically possible)
Physically possible - but in the same sense that the second law is not a physical law.
Another thought experiment that comes to mind is compressed gas in a cylinder. When we open the valve, the gas in the cylinder comes out. In reverse time, the gas would go back into the cannister and the valve would close after the gas went back in. Very low probability of that happening in forward time, though not not 0.
Though it seems weird, because why does the gas go into the cylinder? Because further into reverse-time, something sucked it all out (in forward-time, this machine is the compressor that put the gas in the cylider.) This hurts my brain!
Imagine a ball being thrown up and then falling down, in a parabola. Reversing a video of that still gives you a video of a ball in a normal parabola trajectory.
Well worth watching that episode as it does far better explaining than I do.
Also, geocentrism is actually disproven by numerous observations, which in fact guided the mathematical formulation of our current physics.
One thing is (almost) certain: the laws of physics as we know them (i.e. the Standard Model and General Relativity) are incomplete ("wrong"). That doesn't mean any old model is equivalent or as useful as either, though.
The validity of a coordinate system with the earth stationary at the center is guaranteed by the general principle of relativity. To get the stars to circle around it you would add a radially increasing potential in classical mechanics, or some coordinate shenanigans in GR. These coordinate systems are used in aerospace engineering to get convenient expressions of L1 points, etc.
I know it sounds hard to believe, but if you're willing to bite the bullet that "the center of the universe" has no physical meaning, then earth can't be not the center of the universe any more than it can be.
Certainly, there is merit in practical calculations when we are all this close to the ground where it all seems either flat or at least geo-centric.
But... the movements of the other planets in our solar system were really strange to model in geo-centric models. In short, each of the other planets should rotate around an imaginary axis to compensate for their changing positions in the sky.
Of course, all this is talk about in the context of our solar system. As for us being the center of the universe, well, the same argument holds for any other point in the universe. So, I think it's less likely than me winning the lottery in the next five minutes :)
It’s important to understand that astronomers chose it because it really seemed to provide a better explanation given the knowledge and technology at the time.
Tycho Brahe himself noted that his model could be disproved by observing the stellar parallax effect as the Earth orbits the Sun (if the Earth does move, then the stars would look slightly different throughout the year). This is a real effect, but so small that it couldn’t be observed until the XIX century.
I read an entire book on this subject, published by a Catholic press. There seems to be an active interest in the Catholic science establishment in rehabilitating some of Galileo’s critics.
I disagree.
The sentence «"the center of the universe" has no physical meaning» requires that Earth can't be at the center of the universe, because there isn't a center for it to be at.
You're still allowed any or many arbitrary zero-points, but that's only the center of a number line, nothing else.
But, Earth.x = 42 (in some arbitrary coordinate space), if I understand correctly there isn't a sub-light coordinate space in this universe where Earth.x = undefined.
By analogy, while spherical coordinates are arbitrary, latitude is defined. Arbitrary, but defined.
But the centre of the Earth has an undefined latitude, and a topological subspace consisting of just the surface of the Earth can't hand-wave past that by pointing out that's just a coordinate singularity that can be safely ignored — there isn't a center of the Earth anywhere in that subspace. If the universe is flat and finite (looping), this problem still exists.
And if the universe is unbounded (infinite), that has a different problem because you can't properly define a median of an infinite set[0], so no center exists.
If it just stops suddenly after a certain amount of space, then we get to have a center, but there's no sign of that.
[0] I think. Infinity is easy to get messed up with.
Be patient. It hasn't been evaluated just yet.
Or if I’m lucky enough to have the time to watch the moon move slowly, it feels natural to my senses to say it’s moving across the sky. The moon feels like it’s moving around me. But I can stretch my brain and imagine the reality.
Sometimes math arrives first. We have the new maths (or an problem in current math), and that points to some possibility. Because it’s not observable, ignoring our senses is a requirement to develop that in the model and measurements and experiments. Eventually we are able to observe it.
I’m not familiar with history of astronomy. Would it be the case where the observations that lead to heliocentric thought we nuanced and had to build on more obvious perceptions that things aren’t adding up? Was the wobble of Venus part of that?
And you’re right, old models are useful and remain relevant a lot! The model of time moving linearly will likely always be the most useful model for navigating our daily choices (if we have any at all!)
Your entire experience of the world is defined and limited by the fact that your brain "only processes information in one direction of time" (for lack of better wording). Your personal experience does not necessarily map correctly to the real world. The same is true for both examples.
Our brains like to process events in a linear sequence, from past to present to future, but this view of time might not fully capture how everything in the universe is interconnected. It's possible that our language just can't handle these complex concepts.
So, I don't think anything mentioned in this thread contradicts the idea that "time always moves in one direction" and "entropy always increases".
So no, it's not at all incompatible with retro-causality. When you think about retro-causality, the idea that time "moves" is completely superfluous. Time is probably not even a real thing.
More on topic, I think our existing theories of reality tell us that the future probably affects the past, or at very least, is predetermined. If you know the solution to a differential equation, you know the state at any point in time. There's no going off the rails, so to speak. And if the system is constrained in any dimension (i.e. it's nonholonomic) then the state at any given moment relies on the full trajectory up to that point, as opposed to just the previous state. But you can flip that on its head and say that the future state determines the present trajectory. E.g. to turn a bicycle left, you have to first turn right.
I'll expand here how if the arrow of time actually doesn't exist, the future could change the past without breaking our - current - understanding of physics (tragiclly because we will probably have maybe hundred of years till we change our minds about what are the properties of the universe).
In a range or probabilities of one event, one of the probabilities will always be the one is going to actually happen. Closer to the event to occur the most certain you can be about which one of those, could be the one that will happen.
Here's the catch, you have to change your mind a bit, in our current understanding of physics, the information of the future event which has not happen yet, already exists here in the past for that event.
Now, if you know - and you know - the outcome of an event, you most certainly will be able to choose if you go along that path, or you choose to change the future event to something else. Whoalá, the future changed the past.
Brains of earth continously do this, every second of our entire lives, animal brains do this too, almost all life on Earth has some neurological, physiological, chemical predictive mechanism in place.
An example, you're about to walk across a street, you see a car coming, now your brain "predicts" you'll be hit by that car if you just keep walking, you stop walking to avoid certain death, done, the future changed the past. The information - really close to 100% of probability of death - extracted by the brain from the sheer reality of the universe, allowed you to survive.
And no current understanding of physics got harmed anywhere along the way of the future changing the past.
Granted, I'm not a physicist and I'm sure any physicist working on this totally understands that. Just wanted to point it out.
The biological processes enabling that sequence can be said to have negative entropy.
(It's like a rollback of database transaction, where not only the database state, but also the state of everything, including your brain, is getting rolled back)
Though there's no hard evidence, but if you think, for example, about the efficiency of evolution - it would be much easier to explain if we assume that the unlimited number of iterations is performed. (This is not the only possible explanation, of course- but this one is overlooked IMO)
I would say that compared with the strange ideas like "multiverse", this one is rather benign :-)
Scrambled eggs do actually unscramble spontaneously if you zoom in far enough. The issue is that the rate of scrambling is much higher than the rate of unscrambling so on the whole, you get scrambled eggs.
The amazing thing is that all chemical processes are actually reversible given enough energy and finesse.
Nature doesn't have to obey any particular set of axiom you adopt.
- There seems to be a special direction "down", where things fall by default, because we live in the vicinity of an influential object in space, called Earth
- There seems to be a special direction "forward in time", where things happen by default, because we live in the vicinity of an influential event in time, called Big Bang
If we had stuck to the local Earth context and geocentrism, the objectivity of the "down" direction would remain unquestioned. It's when we started modeling other things outside of Earth, it became clear there's no objective "down" direction, just a more general concept of Gravity.
Carroll's argument is that it's the Big Bang, an extremely low-entropy configuration of the universe, that gives rise to the 2nd Law of Thermodynamics and the resulting emergence of an arrow of time in the forward direction. It's purely a statistical phenomenon at larger scales, and attributable to being "next to an influential event", according to him.
[1] https://www.youtube.com/watch?v=AZsmyTE3j9o
Stars shine until they run out of fuel, and the age of a star - the status of its fuel, the buildup of fusion products - happens as time passes. Life on planets taps into the flow of sunlight from the star (and/or the flow of heat and chemical energy from the a hot planetary core) to generate complex structures in defiance of the regular direction of entropy (not violating conservation of energy, though). So... life reverses the arrow of time?
https://news.berkeley.edu/2016/09/20/new-book-links-flow-of-...
To butcher an insightful quote by (IIRC) Hamming, any positive slope will eventually make up for y-intercept of a constant function.
We cannot observe in any subset of possible universes where entropy is not present or is working backwards-Ergo those possibilities are wholly out of our direct perception.
That does not mean that causality cannot run in reverse, however, only that we cannot interact with those mechanisms in a way that would preclude our existence or observation.
Are photons themselves stratling this entropic boundary since they travel at the speed of light and within their own reference frame are not subject to the passage of time?
Sure, but some claims which cannot be tested experimentally or observationally are nonetheless important. For example, the claim “it’s important that scientific hypotheses be tested experimentally or observationally.”
Models created using both empirical experimentation and logical reasoning match reality much better than those based on "pure logics" (if that even is possible).
At least in France we take as fait accompli that causality is non trivial and that objects are non local at best: either you can consider objects as one despite immense distance between them, or you accept information passed between them in reverse time. Both are hard to swallow.
It doesn't defy the direction of entropy. Frankly, I'm not sure why you have that notion? Entropy is a measure of system's state of equilibrium. Moving energy from a concentrated source, and distributing it more equally (across life forms and other complex structures), is following the direction of entropy, as is it makes energy more equalized, in contrast to the former state where energy levels are more unequal between highly concentrated areas (like stars, the Big Bang), and areas with less energy.
The regular arrow of time from the human perspective, "leaks" changes into the future. The future is constantly being changed by the past.
You can measure those changes by many ways, the 2nd. law of thermodynamics is everywhere just to make sure you see this happening across everything.
So, probably there are other non-discovered underlying mechanisms in the reality that are already signaling changes from the future "leaking" into the past, changing the past right infront of us, without us noticing it.
A probably omnipresent mechanism for observing the future changing the past, valid in the whole cone of light visible to us, is the probability law.
If you have 10 millions of possible events in a probability, one of them is the exact thing it will happen in the future, hence the information of what happens in the future is right here, existing in the past.
Yeah, you can say how would the nature could use this information without powerful processors predicting branches trillions of times per second on Earth right now?
Well, the brain is a pattern predictor, quite several parts of the brain are firmly attached to the physics of the universe, biochemically but what if the pattern prediction mechanisms in the brain are actually an adaptation of the evolution, just like wings to fly, but with those mechanisms the brain uses probability to "see" information from the future, and here in the "present", it changes the past (from the perspective of the future created originally from the past), if the brain "chooses now" to do something different that what originally created the future it "saw" by analizing patterns, essentially evaluating probabilities.
So the Probability Law would be a kind of Inverted 2nd. Law of Thermodynamics.
It would work perfectly as law of the universe: from the future to the past, the revered time of arrow, one single event created "a" future, but from the regular arrow of time, there would a range of probable future outcomes which you cannot precisely say it has "1" (100%) probability of ocurring, right to exact moment till the future becomes the present.
And it was right there all the time, something obvious infront of everybody in the world, like electricity (which was suspected by many across thousands of years, but just "discovered" recently).
https://en.wikipedia.org/wiki/Law_of_total_probability
Roger Penrose proposed that as far as I know, when Carroll was probably a high schooler.
No. At least as early as Arthur Eddington when Penrose was a twinkle in his dad's eye.
This assigns credit to Carroll.
Perhaps given infinite time, we will randomly get back to a low entropy state infinite times, but I don't know enough about the math to say for sure.
It's basically a softer version of Russell's paradox but for cognition and reality.
Hard to summarize, but it's well worth anyone interested in this topic. There's a good bit where he ties the sleeping beauty thought experiment with Boltzmann Brains and consciousness; it blew my mind trying to understand the whole thing.
Just like noticing that "down" actually means "towards the center of the local planet" did not make water suddenly flow uphill.
(On a personal note, I'm actually sympathetic to the article's retrocasual proposition. I suspect reality is non-local and TSVF etc. naturally tend towards non-locality.)
* This is Vice, of course they use the popular understanding and not something more sophisticated.
Why not?
The "arrow of time" almost always requires thermodynamic arguments. And that requires a concentration of "low entropy" to move toward "high entropy". Which, by definition, are "boundary conditions" and not a fundamental part of your physical rules.
If, for example, your universe is entropically uniform, is there an "arrow of time"? And, even if there were, could you detect it?
However, I would like to point out that it's not like we haven't had this kind of issue before. The Bohr-Einstein debates were a good example. Einstein favored a "fields" interpretation of quantum mechanics. Unfortunately, Einstein's interpretation predicted that atomic states wouldn't decay, and that was clearly, obviously wrong, and Bohr very much hammered on that.
Except that Einstein wasn't "clearly, obviously wrong." As you increasingly isolate excited atoms, their atomic states take longer and longer to decay. The problem was that the experiments of the day couldn't create these kinds of singular quantum state systems--they were stuck with systems that were contaminated with lots of thermodynamic interactions.
We may be seeing something similar here. We are just starting to be able to put together the experiments that can probe things like Bell's Inequality. As we isolate these systems, we may find that the systems were contaminated with statistical time and that we get different results when we can isolate them.
What does that even mean? If your universe is entropically uniform there is no “you”.
Nope, and there's a really great 'physics slam' about this, sadly only in German but auto-translate seems fine. https://youtu.be/z64PJwXy--8?t=519
Would we have fluctuations in that state? In which directions they would... Progress?
Isn't what you describe an anomaly like black hole or division by zero, where we cannot understand what actually happens because normal laws break because they are unsolvable with current models?
If time is a true dimension rather than just something we model as a dimension, it's not unreasonable to think that outcomes in the present could be influenced by constraints that exist in the future - if the "universe" function must be valid according to some constraints at all points in the time dimension, "past" states that lead to invalid future states will never occur.
The idea of invalid universe states is of course purely fun conjecture, but this same concept also maps to probable vs improbable universe states as well. If a future state is improbable (in the sense of a Bayesian prior according to some underlying distribution of energy in the universe) that might cause the universe to evolve in a way that seems improbable at the moment by moment level, but is actually the most probable sequence of events when integrated over the entire duration of the universe.
https://youtu.be/L2idut9tkeQ
The idea doesn't seem so different from matter being the default (vs. antimatter), relative speeds much closer to zero than to the speed of light being what's commonly observable etc.
I commented further in this line of though in another comments, about a probable (ironically), "Inverted 2nd. Law of Thermodynamics" of sorts, which it would be basically just the Law of Probability, interpreted from the point of view of not having an actual arrow of time and the fact that we have - all the time, again ironically - the information of what happens in the future (the one probability in the range which ends being the right one, actually ocurring).
Yeah, I know it would be another Law, and the universe would upside down once again for us the poor meatbags, but we were already in this position several times, discovering the electricity, quantum mechanics, relativiy, you name it.