I rationize the multiverse theory this way: There may be events that are purely chaotic. If you could rewind the universe, the outcome would change following a probability. If our universe started, then it is possible for a different universe to start. The initial conditions for any universe may be a set of chaotic events. If it was possible for an infinite number of universes to start, then maybe there is at least one universe for every possible chaotic event that could have occurred in our universe, and infinitely more that could not have occurred in our universe.
>There may be events that are purely chaotic. If you could rewind the universe, the outcome would change following a probability.
Chaos is not the same thing as randomness. Chaos is defined as "completely deterministic, but a small change in the state at one time will produce a large and rapidly growing change in the state at later times," which implies that if you knew today perfectly you could predict the future forever, but if you are even a little bit wrong it will be magnified, eventually, in to being totally wrong.
So chaos is like a cryptographic hash function where a given input always produces the same output, but even a slight change in the input produces massive changes in the output?
You're right that it's not exactly complete. Time-translation symmetry is what would make an experiment "not depend on when the experiment took place," but time-reversal symmetry, another "time symmetry," would mean that it did not matter whether a VCR tape of the experiment was playing forwards or in reverse, so that both directions appeared to be completely reasonable events. (For example a car driving forwards is just as reasonable as a car driving in reverse.) Time translation symmetry appears in real life, but time reversal in general does not.
On the contrary, it is a pretty fundamental assumption in all of our fundamental theories (with some bows and whistles).
A point of confusion might be that the surroundings of the experiment might influence it and the surroundings would depend on whether it is a workday or a weekend, etc. But this is a bad experiment. The correct interpretation is "if my experiment is isolated so that external events do not influence it (like all good experiments), then I will get the same results no matter whether I do it today or wait until tomorrow". Another way to phrase it is "there is no dependence on the variable 't' in the fundamental laws".
This is correct and leads to conservation of energy — to see why, imagine a frictionless pendulum. If you prove that it returns to original position once, you know that it will swing for eternity because if the system is in the same state and only the time has changed, it do exactly what it did previously. Which is to say that the energy of the system will remain constant.
What is the productive meaning of this article? Evidently, the universe does not upload her laws into ArXiv for us to read and link on HN and for that reason people have poured their lives into certain perceptions and publish their findings in hope it carries some productive weight.
The idea that our established views in math and physics are all selective and narrow is certainly correct but I'd like to see where the alternative is. Feels like nihilist rambling.
"These laws of nature appear fine-tuned to bring about life, and in particular, intelligent life."
The "to" implies purpose, and there's no evidence of this. That fact that we exist could only happen in a universe that we can exist in, but this says nothing about why the universe is like that.
"One answer to some of these questions is Platonism (or its cousin Realism). This is the belief that the laws of nature are objective and have always existed"
And the idea that the laws of nature are objective and have always existed does not equate to Platonism. It doesn't mean they are therefore Platonic Forms https://en.wikipedia.org/wiki/Platonism
"The multiverse is another answer that has recently become quite fashionable. This theory is an attempt to explain why our universe has the life-giving laws that it does"
It's really misleading to present the multiverse notion as an attempt to explain a universe suitable for life.
"...while the multiverse would answer some of the questions we posed if it existed, who says it actually exists? Since most believe that we have no contact with possible other universes, the question of the existence of the multiverse is essentially metaphysics."
I think that's misleading - there are stronger theoretical grounds for hypothesising it than what this suggests. I'm not saying there's evidence for it, I'm saying that the quoted statement misleadingly makes it out be an empty speculation.
"Some people say that science studies all physical phenomena. This is simply not true. Who will win the next presidential election and move into the White House is a physical question that no hard scientists would venture to give an absolute prediction. Whether or not a computer will halt for a given input can be seen as a physical question and yet we learned from Alan Turing that this question cannot be answered. Scientists have classified the general textures and heights of different types of clouds, but, in general, are not at all interested in the exact shape of a cloud. Although the shape is a physical phenomenon, scientists don’t even attempt to study it. Science does not study all physical phenomena. Rather, science studies predictable physical phenomena. It is almost a tautology: science predicts predictable phenomena."
I don't agree with that characterisation. Just because it can't give complete predictions of phenomena does not justify saying it doesn't study those phenomena. Just because we can't predict halting doesn't mean we don't study halting at all. The fact that we know for certain that we can't predict halting demonstrates that we study, and have a certain level of understanding of, that phenomenon.
...and I've run out of time to read more of the article.
The multiverse and the many worlds have nothing to do with each other.
Multiverse postulates multiple universes with different laws of physics, while many worlds postulates worlds with the same laws, just different results for quantum events.
You could even have many-worlds inside multiverse. And some multiverse's with and without many worlds.
> The multiverse and the many worlds have nothing to do with each other.
Some examples
"The theory is also referred to as MWI, the relative state formulation, ... multiverse theory or just many-worlds. [...] MWI is one of many multiverse hypotheses in physics and philosophy."
https://en.wikipedia.org/wiki/Many-worlds_interpretation
For those who don't know, the Everett mentioned in the following is the person who came up with the Many Worlds view.
"The Multiverse Interpretation of Quantum Mechanics", by Raphael Boussoa and Leonard Susskind
Abstract: We argue that the many-worlds of quantum mechanics and the many
worlds of the multiverse are the same thing, and that the multiverse is necessary to
give exact operational meaning to probabilistic predictions from quantum mechanics.
https://arxiv.org/pdf/1105.3796.pdf
"Identity and probability in Everett's multiverse", by P Tappenden.
The British Journal for the Philosophy of Science, Volume 51, Issue 1, 1 March 2000, Pages 99–114
https://doi.org/10.1093/bjps/51.1.99
"The Structure of the Multiverse", by David Deutsch
1. Introduction
The idea that quantum theory is a true description of physical reality led Everett
(1957) and many subsequent investigators (e.g. DeWitt and Graham 1973, Deutsch
1985, 1997) to explain quantum-mechanical phenomena in terms of the simultaneous
existence of parallel universes or histories.
https://xxx.lanl.gov/pdf/quant-ph/0104033
> The multiverse and the many worlds have nothing to do with each other.
> (paraphrasing) The terms "multiverse" and "many worlds" are used interchangeably by many.
You two aren't really disagreeing. The parent commenter was just highlighting that there are two totally separate concepts that are associated in public vernacular with a single word.
I take "The multiverse and the many worlds have nothing to do with each other" to mean there does not exist any notion of multiverse that has to do with many-worlds.
You said it has nothing to do with multiverse, not "it has nothing to do with one particular notion of the multiverse". The examples are countering the former. And what about the other examples?
I specifically defined what I meant by multiverse in my first message. You can't nit pick my words by giving them a new definition, then argue that my words don't work for that new definition.
You defined it and treated it as the only meaning the word has, making the blanket statement that MW has nothing at all to do with the notion of the multiverse. So you accept that it does have something to do with how many people use the term?
Did you forget that there is an actual article we are discussing here? And it uses the term? And it has a specific definition of it? The same one I used?
I mean you did object to this article right? Not some other one, that used a completely different definition of the word?
The article is not sacrosanct -- a number of people here, including myself, have made criticisms of it -- and you seem to be forgetting that my point started with a criticism of the article, not of your comment. It, like you, talks of _the_ multiverse in one specific way, and I was pointing out a problem with that. It said:
"The multiverse is another answer that has recently become quite fashionable. This theory is an attempt to explain why our universe has the life-giving laws that it does. One who believes in a multiverse maintains that our universe is just one of many universes. Each universe has its own set of rules and its own possible structures that come along with those rules."
See where it says "The multiverse is" and "This theory is", as if the multiverse notion is only that?
and the full text of my response to that point was
> It's really misleading to present the multiverse notion as an attempt to explain a universe suitable for life.
Yes, but we are not talking about that theory. It's about as relevant as complaining about epicycles.
That theory simply has nothing whatsoever to do with this article, other than the name.
Why are you bringing up a random theory that has nothing to do with article at hand? Is it just because the name reminded you of it?
It is unfortunate that two completely different theories both have the same name, but there's nothing I can do about that. You simply have to pay attention to which one is being discussed.
>Noson S. Yanofsky has a Ph.D. in mathematics from The Graduate Center of The City University of New York. He is a professor of computer science at Brooklyn College of The City University of New York.
Remember the old stereotype[0] of physicists that thought that because they understood physics, they were automatically experts in every field - and so began dispensing "wisdom" to all of the actual experts?
I guess physicists aren't the only ones who are susceptible to this.
I'm pointing out the humor in the fact that the tables have turned on physicsts that do what the author is doing, because now someone is doing it to them.
I think this argument, while true in some cases, is overly dismissive in general. The whole imperative to "stay in your lane" is one of the most destructive developments in modern science. In biology, for example, the field of synthetic biology was initiated by two physicists: Michael Elowitz and James Collins. It has since illuminated foundational biological ideas about the nature and purpose of stochasticity and dynamics of gene expression, perspectives that biolgists wouldn't have captured because they aren't used to thinking about things stochastically or dynamically. I actually think there CAN be cross talk back from biology: physicists, in general, have terrible experimental instincts compared to biologists. There's a huge stagnation in physics because we've chosen maximally difficult experimental means to prove small things over long time scales. Any biologist could tell you that you want to pick simple, cheap experiments that will be resolved over a short time period. Only recently are particle physicists tuning into this perspective, with the recent move to emphasize tabletop experiments.
But no, apparently we should all stay in our lanes and respect experts in different fields to know everything. It's DESTRUCTIVE and DISGUSTING.
Chaos is just a word, created by humans to provide a human expression to another and for me it describes a system that is too complicated at the current moment in time to unravel into a deterministic system.
I enjoy the multiverse theory because of how it makes infinity more imaginable for me and how time does not need to align between universes to recreate the current moment in one universe. The current moment in this universe can even theoretically happen again in the exact same universe when understanding infinity with all the variables aligning again.
Fatalism is how I view reality. If there is a deity, that being is deterministic as well and could effect our lives but still would make it fatalism for us. Although, I fundamentally think Spinoza is correct on the logic & philosophy of god and thus I think there is no deity(s).
>Chaos is just a word, created by humans to provide a human expression to another and for me it describes a system that is too complicated at the current moment in time to unravel into a deterministic system.
For what it's worth, chaos is defined to mean something specific in physics: a system that is deterministic, but where a small change in today will grow in to a very big change in tomorrow, to the point where any error in your knowledge will eventually grow in to being completely wrong. To reiterate, chaotic systems are all deterministic.
If you're not talking about the world but are instead talking about your experience of the world then chaos means whatever it means in that field of study, I guess. But if you want to understand the universe then physicists are the people you'll want to listen to, so you should know what chaos means.
Chaos isn't interpreted in physics, it's defined in physics, and it happens to be deterministic by definition. Many chaotic systems have already been "unraveled in to deterministic systems," including the double pendulum and weather models.
My philosophy is everything is deterministic and how I wrote the above illustrates that with my expression of the word chaos. I don't understand your point?
In this context, a non-deterministic system is stochastic. That means there's an inherent random probability in the behavior. Chaos has no "chance"; you get the same result with the same initial conditions.
To break down the original sentence, "it describes a system that is too complicated at the current moment in time to unravel into a deterministic system," it implies that chaotic systems are not already "unraveled" into deterministic ones. The reality is that chaotic systems are all already deterministic by definition, and in fact many of them are completely "unravelled" (insofar as the equations that govern them are known.)
No, I never once implied chaos systems are not already unraveled into a deterministic one.
Me writing, "it describes a system that is too complicated at the current moment in time to unravel into a deterministic system" uses the word "unravel" as how humans are incapable of understanding all the cause & effects in the current moment of time; when they define it as chaos but may eventually be able to understand all the cause & effects.
I have no understanding to why you wrote your last paragraph in the original comment to me and how the comments transpired from then to now; other than you have a fragile ego to how I prefer to use my expression of the word chaos.
The last paragraph was written because of the use of the phrase "to me," in the original comment, motivating a defense of why it is a good idea to use what the word means to physicists, as opposed to what it means to other groups.
As you said, “it’s just a word,” and words can have several meanings. This is just one example: you gave a definition of chaos “in your philosophy,” but arguing about definitions (and philosophies) is usually pointless.
The first two are about human experiences and the last you will hear first by listening to physicists (because anyone who practices physics is by definition a physicist, I'm including astrophysicists of course). It might sound like a bold statement, but really what I said was kind of tautological.
You self scoped the question as “universe” and any field, subjective or absolute, where 3/4 of your hard problem stuff is unidentified, probably disqualifies you as a generalist expert so I think physics are the furthest from tautology as the universe and our existence can get.
It would be like a coder saying his codebase is 3/4 missing, let alone the runtime, OS, processor, being completely speculative, but then claiming to be an expert matter on computing.
No, you might very well be a micro expert relative to other micro experts in your small corner of your codebase, but on the universe of existence at large?
Perhaps some respect and humility to the whole process are due. ;)
Suppose you are studying a legacy codebase, one left to you with no documentation. You and your colleagues are by definition the only ones working on it, becuase you call anyone who is working on it a colleague. You are only 1/4th done by LOC, but it's not clear what fraction of the remaining lines are autogenerated getters and setters vs real code. Clearly anyone interested in the codebase should talk to your team.
I should also mention that the 1/4th number is comparable to a "by weight" estimate, but what physicists study is the laws of physics which are not measured in that way. Nobody on Earth knows how much physics there is left to discover or if that is even a well formed question.
I have a very healthy love for physics, and am simply attempting to draw your awareness to the complete subjectivity and awe of the universe.
To reallocate the code metaphor, at some point you step back from the monitor and realize you are certainly discovering how Photoshop was written while completely ignoring the images it creates, documenting the MP3 format, but ignoring the music, describing how the tree grows, while missing the forest.
>But also, physicists claim that they do not deal in philosophy, yet the main subject matter of theoretical physics is a collection of old philosophical subjects such as time, space, the cosmos and absolute beginnings of things.
Geometry used to be studied exclusively by philosophers, but after a long string of successes the group of people who specialized in it got renamed to "mathematicians." Likewise at one point natural science was called "natural philosophy." Philosophy is the mother of the sciences but once the kids get established they move out of the house.
>physicists pick and choose "smooth" and solvable system and then claim to reveal the secrets of the universe.
If you are looking for knowledge about the universe, one hundred percent of it will be found in the form of "ideas comprehensible to humans." All of the secrets of the universe that we know are obviously going to be the knowable ones. If you spend time studying things that aren't knowable then by definition you are wasting your time, even if there is an ontological category of "unknowable but true."
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[ 4.1 ms ] story [ 123 ms ] threadChaos is not the same thing as randomness. Chaos is defined as "completely deterministic, but a small change in the state at one time will produce a large and rapidly growing change in the state at later times," which implies that if you knew today perfectly you could predict the future forever, but if you are even a little bit wrong it will be magnified, eventually, in to being totally wrong.
I don't think that this is correct.
A point of confusion might be that the surroundings of the experiment might influence it and the surroundings would depend on whether it is a workday or a weekend, etc. But this is a bad experiment. The correct interpretation is "if my experiment is isolated so that external events do not influence it (like all good experiments), then I will get the same results no matter whether I do it today or wait until tomorrow". Another way to phrase it is "there is no dependence on the variable 't' in the fundamental laws".
The idea that our established views in math and physics are all selective and narrow is certainly correct but I'd like to see where the alternative is. Feels like nihilist rambling.
The "to" implies purpose, and there's no evidence of this. That fact that we exist could only happen in a universe that we can exist in, but this says nothing about why the universe is like that.
"One answer to some of these questions is Platonism (or its cousin Realism). This is the belief that the laws of nature are objective and have always existed"
Platonism is a type of Realism (https://en.wikipedia.org/wiki/Philosophical_realism)
And the idea that the laws of nature are objective and have always existed does not equate to Platonism. It doesn't mean they are therefore Platonic Forms https://en.wikipedia.org/wiki/Platonism
"The multiverse is another answer that has recently become quite fashionable. This theory is an attempt to explain why our universe has the life-giving laws that it does"
It's really misleading to present the multiverse notion as an attempt to explain a universe suitable for life.
There are many other reasons people have proposed it. For example, in the Many-worlds interpretation of Quantum Mechanics https://en.wikipedia.org/wiki/Many-worlds_interpretation
"...while the multiverse would answer some of the questions we posed if it existed, who says it actually exists? Since most believe that we have no contact with possible other universes, the question of the existence of the multiverse is essentially metaphysics."
I think that's misleading - there are stronger theoretical grounds for hypothesising it than what this suggests. I'm not saying there's evidence for it, I'm saying that the quoted statement misleadingly makes it out be an empty speculation.
"Some people say that science studies all physical phenomena. This is simply not true. Who will win the next presidential election and move into the White House is a physical question that no hard scientists would venture to give an absolute prediction. Whether or not a computer will halt for a given input can be seen as a physical question and yet we learned from Alan Turing that this question cannot be answered. Scientists have classified the general textures and heights of different types of clouds, but, in general, are not at all interested in the exact shape of a cloud. Although the shape is a physical phenomenon, scientists don’t even attempt to study it. Science does not study all physical phenomena. Rather, science studies predictable physical phenomena. It is almost a tautology: science predicts predictable phenomena."
I don't agree with that characterisation. Just because it can't give complete predictions of phenomena does not justify saying it doesn't study those phenomena. Just because we can't predict halting doesn't mean we don't study halting at all. The fact that we know for certain that we can't predict halting demonstrates that we study, and have a certain level of understanding of, that phenomenon.
...and I've run out of time to read more of the article.
Multiverse postulates multiple universes with different laws of physics, while many worlds postulates worlds with the same laws, just different results for quantum events.
You could even have many-worlds inside multiverse. And some multiverse's with and without many worlds.
Some examples
"The theory is also referred to as MWI, the relative state formulation, ... multiverse theory or just many-worlds. [...] MWI is one of many multiverse hypotheses in physics and philosophy." https://en.wikipedia.org/wiki/Many-worlds_interpretation
For those who don't know, the Everett mentioned in the following is the person who came up with the Many Worlds view.
"The Multiverse Interpretation of Quantum Mechanics", by Raphael Boussoa and Leonard Susskind Abstract: We argue that the many-worlds of quantum mechanics and the many worlds of the multiverse are the same thing, and that the multiverse is necessary to give exact operational meaning to probabilistic predictions from quantum mechanics. https://arxiv.org/pdf/1105.3796.pdf
"Identity and probability in Everett's multiverse", by P Tappenden. The British Journal for the Philosophy of Science, Volume 51, Issue 1, 1 March 2000, Pages 99–114 https://doi.org/10.1093/bjps/51.1.99
"The Structure of the Multiverse", by David Deutsch 1. Introduction The idea that quantum theory is a true description of physical reality led Everett (1957) and many subsequent investigators (e.g. DeWitt and Graham 1973, Deutsch 1985, 1997) to explain quantum-mechanical phenomena in terms of the simultaneous existence of parallel universes or histories. https://xxx.lanl.gov/pdf/quant-ph/0104033
> (paraphrasing) The terms "multiverse" and "many worlds" are used interchangeably by many.
You two aren't really disagreeing. The parent commenter was just highlighting that there are two totally separate concepts that are associated in public vernacular with a single word.
As best as I can tell the multiverse he describes is not the type with varying laws of physics. He's using yet another definition of the term.
I specifically defined what I meant by multiverse in my first message. You can't nit pick my words by giving them a new definition, then argue that my words don't work for that new definition.
I mean you did object to this article right? Not some other one, that used a completely different definition of the word?
"The multiverse is another answer that has recently become quite fashionable. This theory is an attempt to explain why our universe has the life-giving laws that it does. One who believes in a multiverse maintains that our universe is just one of many universes. Each universe has its own set of rules and its own possible structures that come along with those rules."
See where it says "The multiverse is" and "This theory is", as if the multiverse notion is only that?
and the full text of my response to that point was
> It's really misleading to present the multiverse notion as an attempt to explain a universe suitable for life.
>
> There are many other reasons people have proposed it. For example, in the Many-worlds interpretation of Quantum Mechanics https://en.wikipedia.org/wiki/Many-worlds_interpretation
That theory simply has nothing whatsoever to do with this article, other than the name.
Why are you bringing up a random theory that has nothing to do with article at hand? Is it just because the name reminded you of it?
It is unfortunate that two completely different theories both have the same name, but there's nothing I can do about that. You simply have to pay attention to which one is being discussed.
Remember the old stereotype[0] of physicists that thought that because they understood physics, they were automatically experts in every field - and so began dispensing "wisdom" to all of the actual experts?
I guess physicists aren't the only ones who are susceptible to this.
[0] http://www.smbc-comics.com/comic/2012-03-21
But no, apparently we should all stay in our lanes and respect experts in different fields to know everything. It's DESTRUCTIVE and DISGUSTING.
I enjoy the multiverse theory because of how it makes infinity more imaginable for me and how time does not need to align between universes to recreate the current moment in one universe. The current moment in this universe can even theoretically happen again in the exact same universe when understanding infinity with all the variables aligning again.
Fatalism is how I view reality. If there is a deity, that being is deterministic as well and could effect our lives but still would make it fatalism for us. Although, I fundamentally think Spinoza is correct on the logic & philosophy of god and thus I think there is no deity(s).
For what it's worth, chaos is defined to mean something specific in physics: a system that is deterministic, but where a small change in today will grow in to a very big change in tomorrow, to the point where any error in your knowledge will eventually grow in to being completely wrong. To reiterate, chaotic systems are all deterministic.
If you're not talking about the world but are instead talking about your experience of the world then chaos means whatever it means in that field of study, I guess. But if you want to understand the universe then physicists are the people you'll want to listen to, so you should know what chaos means.
Me writing, "it describes a system that is too complicated at the current moment in time to unravel into a deterministic system" uses the word "unravel" as how humans are incapable of understanding all the cause & effects in the current moment of time; when they define it as chaos but may eventually be able to understand all the cause & effects.
I have no understanding to why you wrote your last paragraph in the original comment to me and how the comments transpired from then to now; other than you have a fragile ego to how I prefer to use my expression of the word chaos.
Bold claim. I would like to ask physicists what chicken tastes like? Or why the mountains are beautiful? Or where the other 73% of our existence is?
It would be like a coder saying his codebase is 3/4 missing, let alone the runtime, OS, processor, being completely speculative, but then claiming to be an expert matter on computing.
No, you might very well be a micro expert relative to other micro experts in your small corner of your codebase, but on the universe of existence at large?
Perhaps some respect and humility to the whole process are due. ;)
I should also mention that the 1/4th number is comparable to a "by weight" estimate, but what physicists study is the laws of physics which are not measured in that way. Nobody on Earth knows how much physics there is left to discover or if that is even a well formed question.
To reallocate the code metaphor, at some point you step back from the monitor and realize you are certainly discovering how Photoshop was written while completely ignoring the images it creates, documenting the MP3 format, but ignoring the music, describing how the tree grows, while missing the forest.
<3
But it’s awe that is subjective, while the universe is completely objective.
But see https://www.johndcook.com/blog/2010/03/30/statistical-rule-o..., which has been discussed on HN not long ago.
Geometry used to be studied exclusively by philosophers, but after a long string of successes the group of people who specialized in it got renamed to "mathematicians." Likewise at one point natural science was called "natural philosophy." Philosophy is the mother of the sciences but once the kids get established they move out of the house.
>physicists pick and choose "smooth" and solvable system and then claim to reveal the secrets of the universe.
If you are looking for knowledge about the universe, one hundred percent of it will be found in the form of "ideas comprehensible to humans." All of the secrets of the universe that we know are obviously going to be the knowable ones. If you spend time studying things that aren't knowable then by definition you are wasting your time, even if there is an ontological category of "unknowable but true."