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CERN Begins New Antimatter Gravity Experiments (phys.org)
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.
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.
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.
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.
Every end has half a stick.
The thing is that while this is interesting, I'm not sure its true. Thanks for this.
It's not even wrong. The sad part is that people modded up this drivel. It's just extrapolating and hand waving.
".. whether antimatter falls down .."
Or maybe it falls up?
There does exist an hypothesis by Marcoen Cabbolet 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.
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