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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.
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.
Gravity doesn't come into special relativity anywhere. General relativity is the most accurate model for gravity we have. If we're modelling the path of a small particle (which antimatter is in our experience) in free fall then its mass isn't really important in GR. It follows the same geodesic through curved spacetime regardless. Massive objects like the sun and earth significantly curve spacetime, but the mass of the antiparticle will have negligible effect whatever sign you choose to put on it if it is small in magnitude. If the sign of the mass mattered then photons and photons have zero mass, then which way would they fall? In practice they fall down, following the geodesic GR describes.
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.
SJW n. One who posts facts.