Physicists Investigate Why Matter and Antimatter Are Not Mirror Images (economist.com) 164
An anonymous reader shares a report: As mismatches go, it's a big one. When physicists bring the Standard Model of particle physics and Einstein's general theory of relativity together they get a clear prediction. In the very early universe, equal amounts of matter and antimatter should have come into being. Since the one famously annihilates the other, the result should be a universe full of radiation, but without the stars, planets and nebulae that make up galaxies. Yet stars, planets and nebulae do exist. The inference is that matter and antimatter are not quite as equal and opposite as the models predict.
This problem has troubled physics for the past half-century, but it may now be approaching resolution. At CERN, a particle-physics laboratory near Geneva, three teams of researchers are applying different methods to answer the same question: does antimatter fall down, or up? Relativity predicts "down", just like matter. If it falls up, that could hint at a difference between the two that allowed a matter-dominated universe to form.
This problem has troubled physics for the past half-century, but it may now be approaching resolution. At CERN, a particle-physics laboratory near Geneva, three teams of researchers are applying different methods to answer the same question: does antimatter fall down, or up? Relativity predicts "down", just like matter. If it falls up, that could hint at a difference between the two that allowed a matter-dominated universe to form.
chaos? (Score:1, Insightful)
Couldn't this be a case of a butterfly flapped its wings billions and billions of years ago, and now we have more matter than anti-matter?
Re: chaos? (Score:1)
Re: chaos? (Score:1)
You mean reverse the polarity of the neutron flow.
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Not if its cross-linked with a redundant melacortz ramistat.
Re: chaos? (Score:2)
Neutrons are their own antiparticle
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No it is not!
Why the funk would it?
https://en.wikipedia.org/wiki/... [wikipedia.org]
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Your right. I think I was thinking of a photon.
My bad. Posting before morning coffee.
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No; the photon is its own antiparticle, as are a few other neutral force carriers (like the Z-boson, and gluons). But the antiparticle of a neutron is different: as per an AC posting above, it's composed of antiquarks. Read all about it in the Wikipedia.
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I go down the gym to work on my glutons. They are ripped!
Anti-neutrons are Different (Score:4, Informative)
This is because neutrons are made of fermions which have different particle and antiparticle states. Only bosons, like the photon, have the same particle and antiparticle states.
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Only bosons, like the photon, have the same particle and antiparticle states
Hang on a minute. TFA mentions trying to measure whether anti particles fall or rise in gravitational fields. Presumably because if there is repulsion, then most antimatter will be long gone. But photons fall in gravitational fields, so has the question been answered?
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But photons fall in gravitational fields, so has the question been answered?
Well yes it has if you believe in general relativity where the gravitational field couples to what we call the 4-momentum of a particle (essentially a 4D vector combining energy and "ordinary" momentum). GR requires that gravitational fields will be attractive to all particles. However, while extremely fundamental, nobody has ever tested this with antimatter. So while everyone is expecting the answer to be that antimatter falls it is nevertheless worth checking because checking the predictions of our theor
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Re:chaos? (Score:5, Insightful)
Quantum physics is ultimately very unsatisfying, no matter how well it works. You always have the feeling that it's a working kludge, but has to the results of us just not understanding something very basic.
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Quantum physics is ultimately very unsatisfying, no matter how well it works. You always have the feeling that it's a working kludge, ...
I agree with the first part of this. But, when I was studying quantum mechanics, I can’t say I felt it was a “kludge”. I felt like it was this completely non-intuitive, abstract mathematical model which had no reason to work... but somehow did, every freaking time it was tested against something as-yet unknown.
It was a real problem for me since I tend to be an intuitive learner. I learned the equations, but never really could wrap my mind around the science as a whole.
Re:chaos? (Score:5, Interesting)
That was effectively my point, there's no question that you can mathematically predict what will happen, most of the time. But this thread is about one of the examples where it doesn't appear to work, along with the various other examples mystery coefficients or mystery energy or mass being kludged in to patch things up.
I think that this apparently "statistical" nature is a function of something very fundamental that we don't yet understand, and some day, somebody will find the reality with a slap to the forehead and a loud "D'OH!"
Note that this has *always* been the case in physics and science in general. Phlogiston theory predicted a lot of things correctly for a long time, for a lot of people who were not morons. Then the edges started fraying, people tried various fixes to try to patch it back together, until someone came along with a conceptual advance, then the old way seems ridiculous and obviously wrong. We are in the "fraying edges" point of the cycle (like the late 1800s).
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I don't really know why people get hung up on the fact that QM is non-intuitive. There are many macroscopic physical phenomena that also defy intuition.
I see the Sun move across the sky every day, but I don't feel the Earth move at all. Intuitively the Sun must orbit the Earth, right? Except that overwhelming evidence beyond my own measly human observation has shown that in fact, the Earth orbits the Sun.*
QM is exactly the same. It defies intuition, but the evidence backs it up. There is no reason to expect
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The Earth is a non-inertial reference frame. When you attempt to view the Solar System from this frame, you will have to introduce fictitious forces to account for the fact that the reference frame you chose is actually accelerating.
So it's not quite as simple as you make it out to be.
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You didn't need to use the asterisk, as the barycenter of the Earth-Sun system is still well inside the sun. I believe it's only a mere 450km from its centre.
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You're right. Next time I'll need a second one just for you. :)
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I don't really know why people get hung up on the fact that QM is non-intuitive. There are many macroscopic physical phenomena that also defy intuition.
QM isn't just non-intuitive, it defies logic. How do you reason about a particle that doesn't have properties until you look at it? How do you think about a world where a cat is alive and dead at the same time?
Most other scientific models are easy to visualize and reason about spatially - until recently, we couldn't see atoms and the subatomic particles of the standard model, but we can easily imagine them. It's easy to think about electrons moving around in a circuit, or about gases expanding and contracti
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How do you think about a world where a cat is alive and dead at the same time?
Incorrectly, since that though experiment was designed to highlight the problem with applying QM to everyday objects and situations. It's literally a "QM doesn't work here" example, and it's amazing that everyone comes away with the opposite conclusion.
Schrödinger did not wish to promote the idea of dead-and-alive cats as a serious possibility; on the contrary, he intended the example to illustrate the absurdity of the existing view of quantum mechanics. [wikipedia.org]
Re:chaos? (Score:5, Insightful)
Schrödinger did not wish to promote the idea of dead-and-alive cats as a serious possibility; on the contrary, he intended the example to illustrate the absurdity of the existing view of quantum mechanics. [wikipedia.org]
Read some context... literally the next line from your quoted article: "However, since Schrödinger's time, other interpretations of the mathematics of quantum mechanics have been advanced by physicists, some of which regard the "alive and dead" cat superposition as quite real."
Schrödinger was very much trying to show that QM theory, which was in its infancy at the time, was absurd and therefore must have been incomplete or flawed . Just as Einstein was trying to do with EPR and when he questioned if the moon was there when nobody looks. They were trying to falsify their own theories by showing how fundamentally ridiculous they were. Of course a cat cannot be alive and dead at the same time. Of course things must continue to exist when nobody is looking at them.
However, they failed in falsifying the theory - instead, they just created excellent examples of how utterly bonkers QM really is. That QM theory (and later experimental evidence) shows that these absurd rules are in fact the ones that govern our reality.
In the words of Niels Bohr: "Anyone who is not shocked by quantum theory has not understood a single word."
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I'm not really sure what the distinction between "logic" and "intuition" in this case is...
I disagree that it's easy to imagine what an atom looks like. If I scaled up an atom of hydrogen so that it was 1m across (instead of 10^-10 m), you wouldn't see anything because the nucleus and the electron would still be microscopic. It certainly won't look anything like this [anatomyand...ologyi.com].
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I disagree that it's easy to imagine what an atom looks like. If I scaled up an atom of hydrogen so that it was 1m across (instead of 10^-10 m), you wouldn't see anything because the nucleus and the electron would still be microscopic.
The "atom as billiards ball" analogy is a reasonable/useful approximation for most situations where you are thinking about large quantities of atoms. Thinking about kinetic theory of temperature, structure of solids, chemical composition of materials, etc.
Really, this is getting at reasoning by analogy, which is one of our primary approaches to understanding. QM defies reasoning by analogy, because there is nothing in everyday experience that is remotely similar to quantum mechanical behavior.
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It's been >10 years since my courses, but I believe I read that Schrodinger himself felt uncomfortable assigning the wave formula to what was supposed to be a probability function - but it was the only thing that mathematically made sense even if it was physically nuts. A lot of it was observation done in the old way, but with some mathematical derivation that didn't necessarily elucidate what's actually occuring at a fundamental level. You have to just believe in probability wave functions without under
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I think that this apparently "statistical" nature is a function of something very fundamental that we don't yet understand, and some day, somebody will find the reality with a slap to the forehead and a loud "D'OH!"
I see no reason to expect this.
Basically, what bothers you is that our intuition, which is formed from macroscopic observations made through our physical senses which were optimized via evolution to enable our survival in a world of macroscopic objects, doesn't map well onto the world of subatomic particles. But why in the world would you expect it to?
Re: chaos? (Score:2, Interesting)
The main problem with pilot wave theory is that it requires faster-than-light transfer of information, which implies that causality can be violated (an effect can precede a cause).
The most popular way to save pilot wave theory is to introduce the concept of implicate order, a bizarre concept that frankly makes the Copenhagen interpretation look like child's play in comparison.
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The main problem with pilot wave theory is that it requires faster-than-light transfer of information, which implies that causality can be violated (an effect can precede a cause).
I really dislike this expression. Causality is the foundation of science.
It isn't causality that breaks, it just means that in the pilot wave theory FTL can happen without breaking causality which means that the pilot wave theory is incompatible with general relativity.
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ampersand l t semicolon
ampersand g t semicolon
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The question is not about why did matter win, but why there is a winner at all.
The quantum butterfly could explain why we are in a pocket of matter, as opposed to a pocket of antimatter, but I think the hypothesis of matter and antimatter co-existing has been disproven. There really seems to be only matter, antimatter is nowhere to be found in significant quantities, and as a result, that matter is fundamentally different from antimatter.
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I have long since believed that the matter that we have in the universe is just the statistically insignificant remainder from an unfathomably larger amount of matter and antimatter that annihilated each other after the big bang..
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But this has always been the question. The question has never actually been why, out of the two, that the one we call matter won. If what we now call antimatter had won, then in that universe we would still have called that matter and its opposite antimatter. So "why did matter win" is how it's spoken of, but really no one has ever really cared why the winner was what we call "matter". The question has only ever been why was
Re: chaos? (Score:3)
It really doesn't matter how chaotic it is at the microscopic level, quantum physics is at heart a statistical beast and the macro level the picture should be consistent. And yet there's more matter than antimatter.
I should note , if antimatter DOES function inversely to matter re gravity , it opens a whole boatload of extremely fun physics implications , the least of which would be the identifying a candidate for the prized unobtanium needed for a warp drive
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if antimatter DOES function inversely to matter re gravity , it opens a whole boatload of extremely fun physics implications , the least of which would be the identifying a candidate for the prized unobtanium needed for a warp drive
And to lift your flying car. You would need a ton or two of antimatter. Collide with another flying car and the explosion would be how big? Enough to create a second moon?
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Yeah I suspect we wouldnt be wanting to use these things in our own atmosphere. God only knows a uranium fusion explosion is nasty enough, and thats a fraction of the truly gargantuan energy released by matter/antimatter reaction
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And to lift your flying car. You would need a ton or two of antimatter. Collide with another flying car and the explosion would be how big? Enough to create a second moon?
Last time I looked this up, it was something like 47 grams of matter converted completely to energy == one megaton of kaboomage.
With matter/antimatter annihilation, a good portion of the energy vanishes into thin space in the form of neutrinos. The ratio was about 60/40, and I don't recall which way, so as a reasonable estimate, I'd pick half. Or, calculate based on the mass of the antimatter, not the antimatter + matter it annihilates with.
So, one tonne == 1 million grams == over 21 thousand megatons.
Not
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I reckon there's a signed where it should be unsigned (or vice versa) somewhere.
CP Violation (Score:5, Informative)
Couldn't this be a case of a butterfly flapped its wings...
Short answer: no, assuming you mean some random fluctuation in the early Universe. For the excess of matter over anti-matter in the early universe to be due to such a random fluctuation, there would have to be some process that allows more matter than anti-matter to be created and we have not seen anything that does this yet.
However, we have seen a bias between matter and antimatter in decays of certain types of particles made of quarks and anti-quarks bound together. While this is not enough to create more matter than anti-matter if the same effect exists in the oscillations of neutrinos then there may just be enough to explain the excess of matter over antimatter. However, this would still not be a random fluctuation but rather that the universe has an inbuilt bias in the laws of physics which favours matter over antimatter.
As an interesting aside this difference, called CP violation, is also the only physics we know of that requires three generations of quarks and leptons to exist. If there were only two generations we could not have a difference at least via this mechanism.
Re: 1st question. (Score:5, Informative)
Various ways of creating antimatter have been used in physics. One is to get a photon (particle of light) to convert into an electron and positron (antimatter equivalent of an electron). Another is to smash a proton into a necleus and create various particles of matter and antimatter and filter them by charge and momentum. If you want learn about antimatter in general, Don Lincoln has some introductory videos on YouTube.
Re:1st question. (Score:5, Funny)
Very, very carefully.
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Very, very carefully.
If all the antimatter ever made by humans were annihilated at once, the energy produced would be just about enough to make a cup of tea.
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Making a cup of tea from energy requires quite a lot of energy!
Re:1st question. (Score:4, Funny)
That sounds very improbable.
Re:1st question. (Score:5, Funny)
Very, very carefully.
If all the antimatter ever made by humans were annihilated at once, the energy produced would be just about enough to make a cup of tea.
Or, at the very least, something almost, but not quite entirely unlike tea.
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World's most expensive tea for sure.
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Behind a lot of borated polythene and lead.
Take a small sample of water containing Oxygen-18, irradiate it with a beam of 19MeV protons and some of the Oxygen-18 will be converted to Fluorine-18. When the Fluorine-18 atoms decay they release an anti-electron.
The polythene slows down the neutrons which are released when other atoms are hit by the 19MeV proton beam, the boron absorbs the neutrons, and the lead absorbs the huge gamma radiation dose produced by bremsstrahlung when the high energy protons hit th
Beta Decay Simplest (Score:2)
Can you explain us how do you create antimatter in this universe?
Smash things together with enough energy or, even simpler, find any nucleus which undergoes beta decay. The most common form of beta decay produces an electron and antineutrino (which is antimatter eventhough it will hardly ever interact) but there is also beta+ decay where a positron (antielectron) and neutrino are emitted.
The latter type is used by medical physicists in positron emission tomography. This can detect tumors too small to be seen any other way by using the two photons produced by the posi
That's easy. (Score:2)
First method: Create isotopes that have a decay mode that emits anti-matter (usually in the form of positrons). This is a tried-and-true method and is already being used in industrial applications of anti-matter.
Second method: Smash particles together with enough oomph. Some anti-matter will be generated. Capture and isolate it.
Re:Problem? (Score:5, Informative)
This problem has troubled physics for the past half-century...
This "problem" is why we are here. How about not calling the existence of the universe a "problem"?
Different kind of problem. (from Google):
Physics : Mathematics
- an inquiry starting from given conditions to investigate or demonstrate a fact, result, or law.
Re:Problem? (Score:5, Insightful)
What's wrong with asking how the universe works?
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What's wrong with asking how the universe works?
. . . no, the universe does not work . . . it gets UBI . . .
Now, what about dark anti-matter . . . what should that stuff taste like . . . ? Or should it be called anti-dark matter . . . ?
Re:Problem? (Score:4, Funny)
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This "problem" is why we are here. How about not calling the existence of the universe a "problem"?
This problem led to Trump running America. We need to understand it so we can make sure the next universe doesn't end up in the same self destructive path after Spaceforce uses North Korean nukes to hit the reset button.
I put my money on (Score:2)
falls down.
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falls down.
I've always thought that antimatter was the missing 'dark matter' and that, as matter creates/is part of normal space-time, that antimatter/dark matter creates it's own sort of space-time that does not interact with normal space-time nor do the two types of matter 'see' each other as they effectively exist in different universes coexisting together but normally unable to interact or one be detected from the other because they exist in separate space-time 'bubbles'.
Strat
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That may be something, but it is not antimatter. Antimatter and matter interact quite readily and so certainly do "see" each other.
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That may be something, but it is not antimatter. Antimatter and matter interact quite readily and so certainly do "see" each other.
Quite true, but that is antimatter that is created within the matter universe. Antimatter created at this universe's inception may be in it's own anti-space-time universe.
Strat
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That wouldn't be antimatter, it would be something else.
That something else would need to be in addition to antimatter in order for the equations to balance.
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No, but it is obligated to behave consistently. If yours doesn't, wake up.
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No, but it is obligated to behave consistently.
No, it is not. See quantum mechanics versus Einsteinian relativity. Also, the event horizon of super-massive black holes. It does most of the time for most things, but that doesn't mean it always does for everything all of the time.
I mean, if it always behaved consistently we wouldn't be here discussing and debating things like 'missing dark matter' now, would we?
Strat
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Write your theory up and mail it to Physical Review Letters. Be sure to attach the correct postage.
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I've always thought that antimatter ...
Then you obviously never had physics in school ... or slept through it.
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I always thought that the anti-matter went in a different direction in time than the matter did, at the creation of the universe. That's why we can't 'see' it, because it's outside our observable universe.
This is actually sort of the thing I'm trying to describe, here. Since matter, energy, and gravity form space-time as we know it, then it would follow logically that antimatter would have it's own corollary that may not be directly detectable in the non-antimatter space-time universe. Since we aren't seeing vast antimatter nebulae, galaxies, etc, the antimatter has to be *somewhere*.
This probably is just proof that I'm not a physicist and have no idea what I'm talking about. :D
Haha! Right there with you! But hey, it's a very, very strange universe we live in. Einstein was just another faceless univers
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" the antimatter has to be *somewhere*."
I have it on good authority -- talk radio -- that the missing antimatter is buried under an end-zone in Giants Stadium. Jimmie Hoffa is buried under the other end-zone.
Note: Some folks claim that the fact that Giants Stadium was torn down a decade ago disproves this theory. But come on folks. Buried is buried.
Re: (Score:2, Interesting)
Accelerator Physicists have factored Gravitational effects into Storage Rings and TOF lines for decades. The assumption has been that Gravity is universally Attractive, and among other things, even Electrons and Positrons having Mass have Gravitational Fields of their own. Since the first TOF measurements of the Antiproton at the Bevatron nearly six decades back, no evidence of any anomalies have been detected. The research here is still ongoing for ever more precise bounds, largely from inferences rather t
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https://www.xkcd.com/955/ [xkcd.com]
Re: I put my money on (Score:4, Informative)
We've never observed Hawking radiation from a black hole. An analog of Hawking radiation has been observed from model experiments, e.g. where a medium has an area that is supersonic so sound waves can't propagate back out of that region.
Re:I put my money on (Score:4, Insightful)
We observe hawking radiation
No we don't. Hawking Radiation is conjecture at this point. The closest known black hole is 2800 LY away, has 11 solar masses, and emits about one particle of hawking radiation every 10 Billion years. That is roughly a googoleth of a watt.
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But it would emit more if antimatter fell up.
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But it would emit more if antimatter fell up.
If antimatter fell up, black holes would not exist.
Re:I put my money on (Score:5, Insightful)
Wouldn't "falling up" mean that the anti-matter somehow breaks out of the curvature of the space and lays waste of Newton and Einstein?
Yes. If anti-matter "falls up", then that blows a major hole in General Relativity. It is extremely unlikely that "falls up" will be the outcome of these experiments.
Look at it this way: Matter falls down, so if anti-matter falls up, and matter and anti-matter annihilate to form a photon (which is its own anti-particle), then the photon should be neutral in a gravitational field. But it isn't. Photons "fall down", which was measured during a solar eclipse in 1919, as the first experimental confirmation of General Relativity.
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photons could be gravitationally attracted to matter and gravitationally repelled from anti-matter.
that would leave things symmetric.
Janus cosmological model (Score:5, Informative)
There is a retired scientist called Jean-Pierre Petit that has some ideas about this question (spoil: this antimater will fall down). This is the Janus cosmological model [youtube.com]
. I do not know if he is right or wrong, but the videos are worth a look
Uh huh. (Score:2)
Trust and Antitrust aren't mirror images either. No one's worried about that. :-)
The extra is in (Score:5, Funny)
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But they shave their balls to compensate weight
A severe test of General Relativity (Score:1)
General relativity is based on the premise that there is no difference between gravity and acceleration, that is, gravitational mass is always exactly equal to inertial mass. If antimatter falls up, the whole theory collapses.
If antimatter repels ordinary matter but attracts itself, I suppose the universe would self-segregate into galaxy clusters made of one or the other. How sure are we that distant superclusters are made of the same stuff we are?
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Very sure. If distant clusters were anti-matter, at some point there would be a boundary. Annihilation at the boundary would be crazy obvious, like "outshines entire galactic clusters at x-ray wavelengths" obvious.
The universe is an gigantic virtual particle pair (Score:2)
Well, perhaps not, but this would explain why this universe is "normal" matter with no "anti"-matter. In the gigantic virtual particle event that created this universe, there would of course need to be a paired "anti" universe where "normal" matter is scarce. Someday in the distant future the two will recombine and balance the books to zero sum... and then our universe will cease to be "The Ultimate free Lunch".
Re: The universe is an gigantic virtual particle p (Score:2)
Nope, the "big U" Universe is always the ultimate free lunch.
CERN courier (Score:5, Informative)
CERN experiments to test the free-fall of antiatoms
https://cerncourier.com/does-a... [cerncourier.com]
It's because (Score:2)
God uses Intel floating point numbers.
Approximately equal, sure, but *exactly* equal? (Score:2)
Similarly, the matter that we have in the universe today might just be the statistically insignificant leftover excess matter that happened to not get annihilated when approximately equal amounts of matter and antimatter were created.
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Theory says identical amounts, not statistically equal. Observation says something else. On the large scale it might simply be uneven distribution, us only seeing a matter heavy region, the probability of that happening may also take some explaining.
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It will fall down (Score:5, Insightful)
This is almost duplicate since I remember a similar article which talked about some experiment by Italian scientists a few years ago.
But again, our current understanding is that gravity is the curvature of space and time. The anti-matter has no choice but to follow that curvature. It cannot pretend that curvature does not exist.
So, if anti-matter were actually fallen up you can throw general relativity out of the window. I do not expect that will happen.
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I am not a physicist but I thought the terminology "curve/warp,etc." and the pop-culture depictions of physical curves are just to describe the mathematical concepts so lay people can comprehend the math concepts. In other words, to anti-matter the mathematical rule could be that the gravity has an opposite effect and pushes. Or, if you need a depiction, the curve is inverted (for the anti-particle) and the anti-particle is still falling down relative to inverted curve.
I am not saying this is what happens
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But again, our current understanding is that gravity is the curvature of space and time.
Gravity is the effect of a time gradient across space.
So, if anti-matter were actually fallen up you can throw general relativity out of the window.
You are correct. Anti-matter can not fall up any more than reversing time can reverse sequences of events.
Dominates? (Score:2)
My money would be on "down", as "up" would also violate the equivalence between gravitational and inertial mass. Unless you're going to sa
", a particle-physics laboratory near Geneva..." (Score:2)
What has happened to Slashdot?
The Alternative Factor? (Score:1)
(Or is the plural of Lazerus, Lazeri?)
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Is that also the part of the story that makes sense?