CERN Begins New Antimatter Gravity Experiments (phys.org) 90
An anonymous reader quotes a report from Phys.Org: We learn it at high school: Release two objects of different masses in the absence of friction forces and they fall down at the same rate in Earth's gravity. What we haven't learned, because it hasn't been directly measured in experiments, is whether antimatter falls down at the same rate as ordinary matter or if it might behave differently. Two new experiments at CERN, ALPHA-g and GBAR, have now started their journey towards answering this question.
After months of round-the-clock work by researchers and engineers to put together the experiments, ALPHA-g and GBAR have received the first beams of antiprotons, marking the beginning of both experiments. ALPHA-g began taking beam on October 30, after receiving the necessary safety approvals. ELENA sent its first beam to GBAR on July 20, and since then the decelerator and GBAR researchers have been trying to perfect the delivery of the beam. The ALPHA-g and GBAR teams are now racing to commission their experiments before CERN's accelerators shut down in a few weeks for a two-year period of maintenance work.
After months of round-the-clock work by researchers and engineers to put together the experiments, ALPHA-g and GBAR have received the first beams of antiprotons, marking the beginning of both experiments. ALPHA-g began taking beam on October 30, after receiving the necessary safety approvals. ELENA sent its first beam to GBAR on July 20, and since then the decelerator and GBAR researchers have been trying to perfect the delivery of the beam. The ALPHA-g and GBAR teams are now racing to commission their experiments before CERN's accelerators shut down in a few weeks for a two-year period of maintenance work.
Re: No anti-gravity in FEDERAL PRISON (Score:2)
Or maybe (Score:3)
Or maybe it falls up?
An observation (Score:5, Interesting)
Can I make an obvious observation.
There are lots and lots of attraction only 'forces' in nature. They're not really forces, they're the net effect of dipolar forces.
Example 1: Stick magnets in a bag, shake it, the magnets will organize to stick together. The NN and SS poles could repel but they always end up stuck together as NS NS.... The forces push apart similar poles, and attract different poles and the net effect is an attraction only force.
Example 2, think of a crystal forming. At the bind site for the molecule, the force is zero. If you squeeze the crystal the force goes negative and the crystal pushes back. But beyond the nano level, the force is attraction only, and reduces according to the square rules, just like gravity. (Think about this force for a moment, as it gets closer, the force increases, at super small distances it decreases to zero, then goes negative. I could label this force 'crystal strong force' or some other name and model it as if its a real force with magic properties, but to do so would be dumb).
Example 3, my spinning dipoles always organize to have a net attraction force. I found they clump like matter, and concluded that gravity isn't caused by a magic 'mass' property, gravity is the measure of this net clumping ability on a large scale. Mass is simply the potential to clump.
Example 4, Do the same as 1 with more complex magnets with multiple poles, they will form magnetic crystals when you shake them up.
So, the lack of an anti-gravity force points to gravity being one of these net organizational dipolar forces.
Which means you won't find an anti-gravity.
It's also why I say you cannot assume a black hole can suck in matter forever, because you don't know how gravity will behave at super short distances. If its a net organizational dipolar force, it goes negative at super small distances. Just like the crystal case, just like my spinning dipole case.
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The thing is that while this is interesting, I'm not sure its true. Thanks for this.
It's not even wrong [wikipedia.org]. The sad part is that people modded up this drivel. It's just extrapolating and hand waving.
Interesting. (Score:1)
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The forces push apart similar poles, and attract different poles and the net effect is an attraction only force.
I'm not entirely sure what you are saying here. The forces push apart and attract, but the net effect is attraction? How does that work?
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Attraction causes a force along the axis between the objects, but a repulsive one as part of a dipole pair is going to induce a torque on the magnets instead, since flipping one of them around to then attract is a lower energy state. The repulsion serves only as a means to move things around until they are attracted instead. Then they are bound to each other.
At least that's my guess what he's getting at.
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Currently I'm going back through high school physics with this model, and finding some real oddities.
You'll get even more out of it when you stop dropping acid so much.
Re:An observation (Score:5, Informative)
Example 2, think of a crystal forming. At the bind site for the molecule, the force is zero. If you squeeze the crystal the force goes negative and the crystal pushes back. But beyond the nano level, the force is attraction only, and reduces according to the square rules, just like gravity. (Think about this force for a moment, as it gets closer, the force increases, at super small distances it decreases to zero, then goes negative. I could label this force 'crystal strong force' or some other name and model it as if its a real force with magic properties, but to do so would be dumb).
This is patently untrue. First, repulsive forces are positive, not negative -- they are the negative gradient of the potential after all. It's attractive forces that are negative. Second, as you squeeze the crystal together, it's Pauli repulsion, not electrostatics, that produces the huge positive (repulsive force). Third, attractive forces at the nanoscale are due to van der Waals (dispersive) interactions, where instantaneous dipoles induce dipoles in nearby atoms, and this instantaneous dipole - induced dipole interaction is attractive. This potential decays as R^-6, so unlike gravity.
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If you use a negative or positive sign for describing forces is completely arbitrary.
I can't remember that we ever used a sign ... why would we? The formula is the same, regardless if something is attracting or repelling ...
Re:Or maybe (Score:5, Insightful)
Or maybe it falls up?
This experiment will check this but it is overwhelmingly likely to find that anti-matter falls just like matter. If it doesn't then things as fundamental as special relativity and quantum mechanics are in for a very significant rewrite.
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I guess Newton's law of gravity would just work with negative masses. And special relativity? Maybe an absolute value of the mass has to be taken somewhere, otherwise I don't seea problem?
Re:Or maybe (Score:4, Interesting)
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Yeah but photons only have zero rest mass, they still have relativistic mass.
Also anti-matter does not have negative mass. Matter with negative mass is called exotic matter, and may or may not exist at all.
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As for anti-particles falling up you really have two choices. If they have a negative mass then we break special relativity because we know that matter+antimatter release energy proportional to their mass but with a negative mass this would be zero. The alternative is that they have a positive mass but fall up because antimatter couples differently t
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Re: Or maybe (Score:1)
The fact that photons do fall in a gravitational field was one of the main observations that verified General Relativity as more accurate than Newtonian mechanics. Google "solar eclipse general relativity" or something like that for the details.
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Re: Or maybe (Score:2)
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Photons don't have an anti particle. ... wow, never heard about that in school ... ... now it drops down and emits an anti photon ... oops. Or was it the other way around? Sorry, no idea which modern school suddenly uses this model of "a photon is its own anti matter
It might be a neat trick to somehow says: a photon is its own anti particle, but in the long run it makes no sense at all.
Suddenly in nuclear physics we have anti gamma decay
A photon hits an electron and it "quantum leaps" into a higher "orbit"
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When we talk about particle-antiparticle pairs generally do you think it's more convenient or less convenient to include photons pairs?
No idea. Why would it be a question of convenience?
Re:Or maybe (Score:4, Informative)
".. whether antimatter falls down .."
Or maybe it falls up?
There does exist an hypothesis by Marcoen Cabbolet [vub.ac.be] that antimatter will fall up (in an environment of matter such as on earth, antimatter would fall down in an antimatter environment according to this theory) which will be tested by those CERN experiments :
https://onlinelibrary.wiley.com/doi/abs/10.1002/andp.201000063 [wiley.com].
Boo! CERN is biased! (Score:1)
I happen to be pro-matter, you insensitive clod!
The real question (Score:2)
I happen to be pro-matter, you insensitive clod!
So is the entire universe. The real question is: why?
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Uhm, actually...
We did not have enough pro-matter for the job, so we had to make you out of protomatter instead.
Sorrrrreeeeeee...
Re:Yes it does (Score:4, Insightful)
Re:Yes it does (Score:5, Informative)
How much inertia it has, however, does not necessarily mean that it reacts to gravity the same way as normal matter.
General Relativity is based on the assumption that inertial mass and gravitational mass are equivalent. IM=GM is one of those things, like P!=NP, "No FTL", and the Riemann Hypothesis, that everyone assumes, so a confirmation will have little effect. However if the answer is IM!=GM, physics will be turned upside down.
Which would be pretty cool [xkcd.com].
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The XKCD strategy doesn't work. The True Believers always welsh* on their bets.
*There is no evidence that this is a slur against the Welsh.
Re:Antimatter shouldnâ(TM)t falls up but (Score:5, Informative)
There is possibility it falls down at different rate. If it falls up, then how is GR going to describe this behavior ?
Neither falling up nor falling at a different rate is consistent with GR.
We can tell by the recoil effect in nuclear reactions that the inertial mass of particles and anti-particles are identical. GR says the gravitational mass must also be identical. So if it isn't, GR would be overturned, and we would need some new theories to explain how the universe works.
Don't hold your breath. If this experiment shows that AM "falls up" it is more likely to be an equipment failure than a correct result. It is that unlikely.
Unlikely to work (Score:2)
This seems extraordinarily unlikely to produce any surprises. Is there any theory or experiment in matter with an opposite electrical charge has anti-gravity? They're distinct fundamental forces.
Re:Unlikely to work (Score:5, Insightful)
We know there is something missing here (that is, why is matter so much more common than anti-matter?) so we need to keep experimenting, process of elimination, until we find the answer.
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> but it's an experiment we can do, so why not do it?
That's a reasonable question. It's a profoundly expensive experiment in terms of electrical power, engineering and scientific time, and the exclusive use of one of the most demanded scientific resources in the world. So those are good reasons to weigh the potential scientific benefit of the results, and include the chance of any usable results.
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> but it's an experiment we can do, so why not do it?
That's a reasonable question. It's a profoundly expensive experiment in terms of electrical power, engineering and scientific time, and the exclusive use of one of the most demanded scientific resources in the world. So those are good reasons to weigh the potential scientific benefit of the results, and include the chance of any usable results.
Umm... what crucial experiments are being blocked by this? They do have a whole organization devoted to scrutinizing experimental proposals to determine the best use of the LHC. Did you not know that?
In the six years now since discovering the Higgs boson, "all" the LHC has done is confirm the standard model in various ways. No new physics at all. But confirming the standard model is a Good Thing, it can only be confirmed by testing it. This is another experiment in this line of tests of existing physics.
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It's like the gold-foil experiment done about 105 years ago that showed us that "solid" items aren't really all that solid.
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Gravity might not be a fundamental force of nature at all, only a side effect of other things.
Google 'entropic theory of gravity'.
Re:Unlikely to work (Score:5, Interesting)
This seems extraordinarily unlikely to produce any surprises. Is there any theory or experiment in matter with an opposite electrical charge has anti-gravity? They're distinct fundamental forces.
The quantum mechanical model of antiparticles is that they are normal particles which are travelling back in time. It's a bit nonsensical from a non quantum mechanical persepective and it's not time travel as you might think of it. But if you time-reverse an electron and calculate how it behaves it behaves like that particle we can observe known as the positron.
It makes other things neat. For example accelerating electrons emit photons, or the emission of a photon causes the electron to accelerate. So far so good. If you take the time travel model then annihalation is an example of that. An electron and positron meet and get drstroyed emitting a photon. Or an electron amits a photon and changes direction in time rather than space and goes backwards as a positron. From a forward time point of view that looks like an electron and positron coming togther.
Pair production and annhilation just becomes a single electron whizzing round in circles in time.
IOW in the rather peculiar world of quantum mechanics a lot of observable things are modelled to within measurement error as time-reversed particles. Sure it's a mathematical abstraction but it works.
Quantum mechaices has no model of gravity. If an electron travelling forwards in time falls into a graviy well what do you think a time-reversed one might do? GR says it has mass so it's attracted and falls down. That seems to be the most popular view. But QM says it's time reversed so... what?
The answer is we won't know for sure.
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no you're just referencing what is called the Feynmanâ"Stueckelberg interpretation of anitmatter. It's a useful model for property prediction BUT it is not considered "true", antimatter is not considered to be going backwards in time, in bulk it is subject to the same time evolution of entropy as ordinary matter.
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Every means of testing GR (and any other scientific theory) that can be tried, should be tried. Regardless of result we increase our knowledge - we may (with small probability) overturn the expected result, or we add yet another method of confirming our best model.
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there are many other differences than just charge in antimatter. Isospin, parity, baryon or lepton number, strangeness are reversed too.
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Hmm (Score:1)
>ALPHA-g began taking beam
That sounds pretty dirty.
But not as bad as ELENA doing it to GBAR.
I'm guessing the results will be ... (Score:4, Funny)
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For one moment I was reading anti-climax and was scared ... but then my GF snorted ...