It's much harder to come by then traditional "incredibly hard to come by" substances like precious metals or coral snake venom; harder to store, harder to study, and consequently much more expensive. Keep in mind that something like a coral snake's venom goes for more than $1000 a gram (Platinum being ~$30), but antimatter according to NASA estimates? $62.5 trillion USD per gram.
Gosh, I can only imagine how terrifying a whole gram of antimatter would be. It's kind of a good thing we can only generate it in such minuscule quantities.
I just want to say how much I appreciate you leaving the ~50% of energy released as neutrinos out of your explosive yield estimate, you almost never see that.
At least nuclear weapons only go off when the detonation explosives are triggered in exactly the right way. Anti-matter goes boom if anything goes wrong with the confinement system.
Of course this leads into the realistic aspect of science fiction... sufficiently advanced drive technology is indistinguishable from a weapon of mass destruction. We love to talk about fusion drives or antimatter reactions propelling us beyond Earth, but the truth is that such technology has a very dark side and one we're historically likely to exploit.
Note: The second one has very interesting implications for safety of citizens in countries possessing such devices. Especially given the number of accidents in nuclear transportation and command/control. ;)
I always wonder why photon is its own anti matter. If it was not so, we wouldn't be able to study anti matter with lasers for example.
Also, why is the anti particle pair of a charged particle the opposite charge, but neutral particle/anti particle pair are both chargless? Though it does make sense that in order to cancel each other out, it must be so..
I would say we live in a strange world but I don't know if a non strange world would even exist.
> That's just the definition of an antiparticle - same as the particle put opposite charges.
Well, a bit more is needed. If a particle has no charge, then it is possible for it to be its own antiparticle, but it is not necessarily so. The photon is neutral and is its own antiparticle. The neutron, on the other hand, is neutral but is distinct from the antineutron. It is still an open question whether the neutrino is its own antiparticle.
If a particle has no charge, then it is possible for it to be its own antiparticle, but it is not necessarily so. [....] The neutron, on the other hand, is neutral but is distinct from the antineutron.
The neutron is only electrically neutral, there are also weak isospin and color charge. Antimatter is not only concerned with electrical charge but with charges in general. In case of the neutron and antineutron this becomes obvious if you compare the quark content of both.
Regarding that suspended frog... is being suspended in magnetic levitation painful for the frog? Or could this, one day, be used to create artificial gravity in space for humans?
A very strong magnetic field has bad health (neurological and intracellular) consequences. I can't find a good citation, but this blog post should help explain the risks.
The frog levitates at 16 tesla. That's a long way from the fields the article talks about. Nevertheless, given that our brain reacts to magnetic stimulation, I'd be wary of using it as artificial gravity.
Inside a homogeneous magnetic field there is no force. It's kind of like being under very high pressure- humans can survive many hundreds of psi as long as the pressure is equal inside and outside the body.
The danger comes when there is a gradient to the field, as happens outside the coil. Then ferromagnetic material wants to move from the low to high field, like high pressure water will want to move to low pressure. As long as you're inside the high field area, you're okay.
This is part of the reason why people can be MRI'd even with shrapnel in their bodies. When the shrapnel is in the center of the volume being imaged, the field is relatively homogeneous except for the small induced gradient field. The shrapnel is already "touching the magnet", so it doesn't feel much more pull.
Considering the original comment to which I'm ultimately referring, can you actually imagine such as situation as it relates to humans and "artificial gravity"? Presumably we're talking about the scale of a space craft or station...
Yeah, the entire station would be basically a giant solenoid. If you're outside the coil the artificial gravity doesn't work. You can have metal flying around without artificial gravity, but you can't get the artificial gravity in an environment that metal will accelerate inside.
Only in an oscillating field. In an MRI the gradient coils cycle on and off rapidly (rapid in human terms), which causes minor hysteresis heating. In a static field there would be no heating.
The human brain is almost completely unreactive to magnetic fields. The trick with TMS is that it creates an extremely short pulse- a time varying field, which induces a voltage at the focal point of the field. This voltage is on the order of 100 mV, which is well in excess of what is needed to trigger all of the nerves in an area to fire.
Static fields do not have the same effect unless you are moving through them at immense speed, eg passing from a region of 2 Tesla to 0 Tesla in a few milliseconds which would mean moving around the speed of sound through an MRI.
That article is a completely different kind of "very strong". Our "very strong" is a 1-2 Tesla, the strength of a high end neodymium magnet. Levitation is about 10x higher than that but in practical terms, it's not really that different from holding a big magnet to your face. It does not affect any significant chemical reactions.
This article is talking about fields so high that chemistry fundamentally breaks down and matter breaks into individual atoms. This only happens in neutron stars. It's 1,000x stronger than any field made by humans and 10,000x stronger than levitation fields. At these fields the atoms literally change shape.
Artificial gravity is easy to produce in space: just create a rotating frame of reference, such as a torus-shaped living quarters. Even if you set aside the other problems with very strong magnetic fields, generating one powerful enough to accelerate humans at roughly 9.8m/s is going to require a LOT of energy and some very bulky, finicky equipment (such as cooling for the superconductors). At that point why not just build a large motor and rotate the station?
No, the frog is not at all aware of what is happening. Basically to it, gravity has just shifted to higher up rather than always down.
This... would work for artificial gravity, you just need massive coils in the floor and ceiling. This field is 10-100x higher than the quench fields of superconductors[1], so there is no known technology that would be capable of making fields on such a large scale continuously. Even if there was the power requirements would be on a different scale. If we had that capability we would probably be way beyond having to worry about things like gravity.
Because it does not exist outside of the minds of the "scientists" "studying" it?
Proof of its existence before down-voting would be appreciated.
Update: a quick overview of how easily sectarian beliefs could be held with support of nothing but opinions of the followers could be found a in my older comments.
Why, the very same distinction as between a science and a religion - a proposition which lack empirical verification cannot be used as a valid premise. One single logical flaw (assumption of existence of a mere abstraction) is enough to discard the whole mental construction or a model.
Most of so called modern science is based on a sectarian consensus of ignoring the logical inconsistencies.
Petabytes of data from particle accelerators that only make sense if anti-particles exist.
You seem to be operating under the assumption that anti-matter is something weird and exotic. It's not. It's engineering. We use anti-matter in medical devices at your local hospital: https://en.m.wikipedia.org/wiki/Positron_emission_tomography
We're checking to see if our predictions are correct because that is proper science, and it's hard to have a lot of antimatter, but there is basically no reason to doubt it's existence, unless you want to write off all of particle physics. As that is arguably the most solid science we have, you'd basically be writing off all science.
I would have said "supports with evidence" rather than "confirms", in the spirit of falsifiable science. Your argument asks for proof of antimatter, as though science is a religion. But science is a discipline whose purpose is to attempt to falsify ideas, not elevate them to the status of beliefs. Those ideas that resist falsification represent our current understanding of nature, and any of them can be replaced by new theories and new evidence.
There is nothing hinkey about that experiment. However, your confusing modeling with simulation. If I create a scale model to test flood controls it's not 1:1 with reality, but it is constrained by the physical world. Which is what separates experiments from simulation.
CERN claims to have created anti-hydrogen atoms in 1995 [1], and Fermilab confirmed the claim shortly after by doing the same thing.
You're perfectly free to doubt these claims (for whatever strange reason), but doing so would be pretty arbitrary, unless you consistently distrust the entire scientific establishment, in which case, your "bullshit detector" is badly broken because it keeps reporting too many false positives and needs to be retrained.
My bullshit detector is quite simple actually. When I see a mathematical simulation (a probabilistic model) instead of a directly observed and measured natural phenomena we probably dealing with a socially constructed bullshit.
It is the same kind of crap as CDS or any other modern sect but in theoretical physics - the way to earn a decent living by bullshitting mere mortals.
Your bullshit detector is hopelessly broken. At a certain point, these "mathematical simulations" (i.e. effects observed in a laboratory) end up having real world applications. Anti-matter has already crossed the threshold of being "effects observed in a laboratory" to actual applied science. Hospital PET scans use anti-matter regularly for brain scans. [1]
I'm not educated in the subject, so I'm asking sincerely, but wasn't Higgs boson first speculated in a "mathematical / probabilistic" model, before being empirically confirmed through direct observation?
There wasn't any direct observation, only interpretation of the data from vastly complex instruments which has been made according to some set of beliefs (like Egyptian pyramids).
That's the point - there were no direct observation.
The "proof" of existence of, say, photons is that green thing outside your window. The proof of correctness of the atomic theory you could see in the mirror. The proof of existence of antimatter are some petabytes of data from some man-made tool.
It appears that you're suffering from a bad case of confirmation bias. There's plenty of evidence for the existence of antimatter, one need only investigate with an open mind.
> When I see a mathematical simulation (a probabilistic model) instead of a directly observed and measured natural phenomena [sic] ...
I'm not sure if anti-matter is real or fake, but I remember watching a very fascinating cosmology lecture that explained one of the reasons why scientists came up with the idea - I can search out the link if you're interested.
You are probably confusing antimatter with dark matter or dark energy. Antimatter is not some idea scientists invented to fix a theory: it has been observed, produced and even has normal life applications like PET scan.
It's quite tractable, and even has cool cloud chamber pictures of the trails of the objects claimed to be positrons ("Positive electrons," at the time.)
I often hear the meme that the burden of proof lies on the person making the extroardanary claim, where I assme the "extraordinary" side is chosen by the ambient culture. This might be fair, but people should stop sticking to it with such fervor - the entire point of the scientific consensus is that there is lots of evidence for it lying around. It shouldn't be hard to find a little to share.
Also, I'd like to point out that philisophical debates are the only environment in which idealism (or even social constructivism of science, for that matter) can survive! ;) If you are going to take the time to have a discussion, it will be more fruitful to educate, and share the (very interesting!) reasons behind the theories that we spend so much time studying.
> Because it does not exist outside of the minds of the "scientists" "studying" it?
The theory behind antimatter first appeared in an equation written by P. A. M. Dirac[1]. Experimental confirmation came in 1932 in a cloud-chamber experiment conducted by C. D. Anderson[2]. Antimatter is now regularly generated and detected in many different ways, in experiments and observations that aren't based on conjecture.
> Proof of its existence before down-voting would be appreciated.
Done (replacing "proof" with "evidence", since there are no proofs in science).
Because antimatter has both strong theory and experimental validation, the burden of evidence is yours, not ours. This doesn't mean the idea of antimatter cannot be falsified by new theory and/or new evidence -- as with all science, falsifiability by empirical evidence is a requirement.
My point is simply that one who challenges a well-supported scientific theory has the burden of evidence. And calling for evidence, when there's already copious evidence available, distorts the facts. It's like anti-evolutionists saying "teach the controversy" when there's no controversy.
Your comments on this aren't really a good fit for HN. For one thing, they get uncivil pretty quickly when arguing—that's bad. More generally, accounts that comment to push some agenda, even a purely intellectual one, are not a good fit for HN. We're looking for thoughtful conversation here, not idées fixes.
There is nothing wrong with that. All my comments are based on a few simple assumptions. First, that probability itself is a social construct and cannot be used as a tool to establish any criteria of existence. A close-enough model could be made but there still will be a gap between the model and actual reality, which could not be removed by any amount of math or modeling. Only by replicated empirical validation, like in the case of proving that DNA is indeed the genetic material.
The second argument is based on the first, and it is the principle that a simulation is not a valid experiment for confirming an existence of any phenomena whatsoever because it is based on dogmas created out of math and modeling, not measurable and replicated direct observations. The process of producing a highly sophisticated model is closer to a theology rather than a science, and this is the point.
With these principles it is easy to argue that this or that advanced theory could be mere a socially constructed set of beliefs which exists, like any other such social phenomenon, to benefit certain social group, say, clergymen. There is no idees fixes here. Just a bit of scepticism, philosophy of mind and sociology
The problem is that it gets tedious if you use HN to promote an agenda, just as conversation in person would be if someone were always changing the subject this way. HN threads are supposed to be good conversation, so please just don't do this.
If there were regions of antimatter in the universe, then there would be boundaries with regions of matter. And on those boundaries a lot of matter antimatter annihilation would happen, we would see those boundaries glow in energetic gamma light. We don't see something like that, therefore there are probably no large region of antimatter in the universe.
Gotcha, makes sense. Are we sure the density of the intergalactic medium is high enough to make interactions between matter and antimatter produce light visible from long distances, though?
Isn't space mostly empty? Aren't galaxies like millions of light years apart, and don't they collide only incredibly rarely? If some galaxies were antimatter and some matter, how would we know?
The space between galaxies is not completely empty, there is still about one atom per cubic meter. Boundaries in outer space would stretch across billions of square light years, enough space to generate noticeable signals even at such low densities.
It is the most energetic reaction possible. We can see the background radiation of the universe- hot objects give off heat, even when they are very, very cold. The universe glows like it's 3 degrees above absolute zero, and we can see it. Compared to that antimatter annihilation would look very bright indeed.
That question is a nonstarter, essentially. Physics is interested and concerned with why the observable universe has almost no antimatter, so asking "what if all the antimatter is outside the observable universe" doesn't actually answer the question.
One could maybe argue that there has to be some fundamental asymmetry between matter and antimatter. If there were none, you have to find a good explanation why there was not the same amount of matter and antimatter right after the Big Bang and why therefore not all matter and antimatter just turned into photons leaving behind an empty universe. If on the other hand there is an asymmetry and matter is favored over antimatter, then the matter we see today would just be the difference left over after all the antimatter annihilated. In that case there seems to be no obvious reason why regions should form.
It's reasonable to suppose that if in one experiment you replace each particle by it's antiparticle you will get the same result. (Symmetry C) The problem is that this is not true in all experiments :(
It's reasonable to suppose that if in one experiment you make a mirror image of all the part of the experiments, with the mirrored version of all the velocities and spin, you will get the same result. (Symmetry P) The problem is that this is not true in all experiments :(
(I'll skip T symmetry.)
For some technical reason it's more easy to expect that if you combine both symmetries and change all particles by the antiparticle and make a mirrored version, you will get the same result. (Symmetry CP) This is almost almost almost true. Not completely true, but it's difficult to make an experiment where the result is different.
So, in some experiments the CP version is different from the original version. It is possible to measure this in a laboratory, and this is one possible explanation of the different of the amount of mater and antimatter around us, but no one is sure about the details. See https://en.wikipedia.org/wiki/CP_violation#CP_violation_and_...
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[ 2.1 ms ] story [ 56.4 ms ] threadSure, it's bad, but I only sometimes lose sleep over all the nukes, so…
There's something fascinating about this sentence, but I can't quite put my finger on what it is.
Or even a small percentage, if antimatter becomes cheaper.
In fact, I'd go as far as to suggest that — if you can figure out how to make and keep it — world peace is much better than having any military.
http://cui.unige.ch/isi/sscr/phys/anti-BPP-3.html
https://arxiv.org/abs/physics/0507125
Note: The second one has very interesting implications for safety of citizens in countries possessing such devices. Especially given the number of accidents in nuclear transportation and command/control. ;)
Also, why is the anti particle pair of a charged particle the opposite charge, but neutral particle/anti particle pair are both chargless? Though it does make sense that in order to cancel each other out, it must be so..
I would say we live in a strange world but I don't know if a non strange world would even exist.
That's just the definition of an antiparticle - same as the particle put opposite charges.
Though it does make sense that in order to cancel each other out, it must be so..
That's right, this is required to maintain charge conservation in annihilation processes.
Well, a bit more is needed. If a particle has no charge, then it is possible for it to be its own antiparticle, but it is not necessarily so. The photon is neutral and is its own antiparticle. The neutron, on the other hand, is neutral but is distinct from the antineutron. It is still an open question whether the neutrino is its own antiparticle.
The neutron is only electrically neutral, there are also weak isospin and color charge. Antimatter is not only concerned with electrical charge but with charges in general. In case of the neutron and antineutron this becomes obvious if you compare the quark content of both.
I speculate that that is because Photons are 'transcendent' (in some some sense).
https://gravityandlevity.wordpress.com/2015/01/12/how-strong...
The danger comes when there is a gradient to the field, as happens outside the coil. Then ferromagnetic material wants to move from the low to high field, like high pressure water will want to move to low pressure. As long as you're inside the high field area, you're okay.
This is part of the reason why people can be MRI'd even with shrapnel in their bodies. When the shrapnel is in the center of the volume being imaged, the field is relatively homogeneous except for the small induced gradient field. The shrapnel is already "touching the magnet", so it doesn't feel much more pull.
Static fields do not have the same effect unless you are moving through them at immense speed, eg passing from a region of 2 Tesla to 0 Tesla in a few milliseconds which would mean moving around the speed of sound through an MRI.
This article is talking about fields so high that chemistry fundamentally breaks down and matter breaks into individual atoms. This only happens in neutron stars. It's 1,000x stronger than any field made by humans and 10,000x stronger than levitation fields. At these fields the atoms literally change shape.
This... would work for artificial gravity, you just need massive coils in the floor and ceiling. This field is 10-100x higher than the quench fields of superconductors[1], so there is no known technology that would be capable of making fields on such a large scale continuously. Even if there was the power requirements would be on a different scale. If we had that capability we would probably be way beyond having to worry about things like gravity.
[1]http://hyperphysics.phy-astr.gsu.edu/hbase/Solids/scbc.html)
Proof of its existence before down-voting would be appreciated.
Update: a quick overview of how easily sectarian beliefs could be held with support of nothing but opinions of the followers could be found a in my older comments.
Most of so called modern science is based on a sectarian consensus of ignoring the logical inconsistencies.
But go ahead, which experiment confirms existence of antimatter?
You seem to be operating under the assumption that anti-matter is something weird and exotic. It's not. It's engineering. We use anti-matter in medical devices at your local hospital: https://en.m.wikipedia.org/wiki/Positron_emission_tomography
We're checking to see if our predictions are correct because that is proper science, and it's hard to have a lot of antimatter, but there is basically no reason to doubt it's existence, unless you want to write off all of particle physics. As that is arguably the most solid science we have, you'd basically be writing off all science.
There are hundreds, but let's provide the first: https://en.wikipedia.org/wiki/Positron
I would have said "supports with evidence" rather than "confirms", in the spirit of falsifiable science. Your argument asks for proof of antimatter, as though science is a religion. But science is a discipline whose purpose is to attempt to falsify ideas, not elevate them to the status of beliefs. Those ideas that resist falsification represent our current understanding of nature, and any of them can be replaced by new theories and new evidence.
There is nothing hinkey about that experiment. However, your confusing modeling with simulation. If I create a scale model to test flood controls it's not 1:1 with reality, but it is constrained by the physical world. Which is what separates experiments from simulation.
You're perfectly free to doubt these claims (for whatever strange reason), but doing so would be pretty arbitrary, unless you consistently distrust the entire scientific establishment, in which case, your "bullshit detector" is badly broken because it keeps reporting too many false positives and needs to be retrained.
[1] https://home.cern/topics/antimatter/antimatter-cern
It is the same kind of crap as CDS or any other modern sect but in theoretical physics - the way to earn a decent living by bullshitting mere mortals.
[1] https://en.wikipedia.org/wiki/Positron_emission_tomography
That's the point - there were no direct observation.
The "proof" of existence of, say, photons is that green thing outside your window. The proof of correctness of the atomic theory you could see in the mirror. The proof of existence of antimatter are some petabytes of data from some man-made tool.
> When I see a mathematical simulation (a probabilistic model) instead of a directly observed and measured natural phenomena [sic] ...
Experimental report: https://en.wikipedia.org/wiki/Positron
Picture: https://upload.wikimedia.org/wikipedia/commons/thumb/6/69/Po...
Also, "a ... phenomena" should be "a ... phenomenon".
It's quite tractable, and even has cool cloud chamber pictures of the trails of the objects claimed to be positrons ("Positive electrons," at the time.)
I often hear the meme that the burden of proof lies on the person making the extroardanary claim, where I assme the "extraordinary" side is chosen by the ambient culture. This might be fair, but people should stop sticking to it with such fervor - the entire point of the scientific consensus is that there is lots of evidence for it lying around. It shouldn't be hard to find a little to share.
Also, I'd like to point out that philisophical debates are the only environment in which idealism (or even social constructivism of science, for that matter) can survive! ;) If you are going to take the time to have a discussion, it will be more fruitful to educate, and share the (very interesting!) reasons behind the theories that we spend so much time studying.
The theory behind antimatter first appeared in an equation written by P. A. M. Dirac[1]. Experimental confirmation came in 1932 in a cloud-chamber experiment conducted by C. D. Anderson[2]. Antimatter is now regularly generated and detected in many different ways, in experiments and observations that aren't based on conjecture.
> Proof of its existence before down-voting would be appreciated.
Done (replacing "proof" with "evidence", since there are no proofs in science).
Because antimatter has both strong theory and experimental validation, the burden of evidence is yours, not ours. This doesn't mean the idea of antimatter cannot be falsified by new theory and/or new evidence -- as with all science, falsifiability by empirical evidence is a requirement.
1. https://en.wikipedia.org/wiki/Dirac_equation
2. https://en.wikipedia.org/wiki/Positron
That could be a good operational definition of what is meant by the word 'sectarian'.
The second argument is based on the first, and it is the principle that a simulation is not a valid experiment for confirming an existence of any phenomena whatsoever because it is based on dogmas created out of math and modeling, not measurable and replicated direct observations. The process of producing a highly sophisticated model is closer to a theology rather than a science, and this is the point.
With these principles it is easy to argue that this or that advanced theory could be mere a socially constructed set of beliefs which exists, like any other such social phenomenon, to benefit certain social group, say, clergymen. There is no idees fixes here. Just a bit of scepticism, philosophy of mind and sociology
[1] https://en.wikipedia.org/wiki/Baryon_asymmetry#Regions_of_th...
It's reasonable to suppose that if in one experiment you make a mirror image of all the part of the experiments, with the mirrored version of all the velocities and spin, you will get the same result. (Symmetry P) The problem is that this is not true in all experiments :(
(I'll skip T symmetry.)
For some technical reason it's more easy to expect that if you combine both symmetries and change all particles by the antiparticle and make a mirrored version, you will get the same result. (Symmetry CP) This is almost almost almost true. Not completely true, but it's difficult to make an experiment where the result is different.
So, in some experiments the CP version is different from the original version. It is possible to measure this in a laboratory, and this is one possible explanation of the different of the amount of mater and antimatter around us, but no one is sure about the details. See https://en.wikipedia.org/wiki/CP_violation#CP_violation_and_...
s/is/are/