[anodari]

A friend in college believed in the concept of a matter-repelling antimatter drive that generates propulsion by one repelling another. However, this experiment demonstrates that it may not be possible.

Could this experiment enforce theories that propose gravity operates differently from quantum theory?

[WJW]

Not really, as the current dominant theory already predicted that gravity affected antimatter in the same way as normal matter. This experiment affirms the standard model rather than disproving it.

[rnhmjoj]

You're probably thinking of exotic matter with negative mass, not antimatter. Antimatter is matter made of (elementary) antiparticles, which are identical to the usual particles expect they have opposite electric charge.

So, we didn't expect there would be any difference as far as gravity is concerned.

[eigenket]

Antimatter has opposite charges for all charges, not just electric charge. Anti-electrons have opposite lepton number, anti-quarks have opposite flavour charges etc. This is true for all the charges we understand in the standard model.

[Ygg2]

Wdym. Standard model suggest anti matter will behave like regular matter.

[phkahler]

The Standard model doesn't include gravity.

[rob74]

That was my first thought too: all those sleek (or less sleek, as in The Fifth Element) anti-gravity flying cars from sci-fi films just became a little less probable...

[thfuran]

Did they? If you can stick a nontrivial amount of antimatter in a car, surely you have the energy budget to lift the thing off the ground.