Talk:ALPHA experiment

Interaction with 'gravity' ?

This is maybe a naive question, I am not a physicist.

The article says : "antimatter interacts with gravity in a way similar to regular matter" (OK) and later "The findings rule out a 'repulsive [antigravity]', as previously theorized by some in the field." (??).

I just read a book also saying that this experiment would disprove the possibility that antimatter has a negative mass (I assume that it means, "would produce antigravity").

I don't understand why this experiment would prove such thing. The General Relativity says that the gravity is our perception of the warp of space-time by mass. Thus any particle follows a straight and constant movement in the warped space-time whatever its own mass. Thus it is absolutely logical that antimatter does this, it is the weak equivalence principle, right ? You get the same movement, depending only on the initial speed vector, if the particle has a positive mass, no mass at all (photons) or, if it would exist, a negative mass. You cannot tell anything about the particle's mass using the gravitational effects (you would need to apply an actual force, such as the electro-magnetic force, to measure the "inertial" mass).

But as I understand the result doesn't say anything about how antimatter warps the space-time. If it had a negative mass, it would, maybe, warp it the other way, but you absolutely cannot know because the mass of a few anti-atoms is too small to get any measurable effect.

Am I right ? Mikemln (talk) 09:03, 11 May 2026 (UTC)