Does antimatter have positive or negative mass?

[MikeL#]

Black holes suggest anti-matter has negative matter but is this true?
I think anti-matter has positive mass - e.g. a positron and electron annihilate giving off 0.5MeV + 0.5MeV photons where these photons have a huge positive energy. If the positron had negative mass then there would be no 1.0MeV of photon energy created.
But when 'explaining' evaporating black holes (e.g. https://en.wikipedia.org/wiki/Hawking_radiation#Overview)- matter [e.g. electron] and corresponding anti-matter [positron] are created out of 'the vacuum', If the electron is ejected, then the positron is absorbed in the black hole which loses mass. In this case the positron mass is negative.
So does anti-matter have positive or negative mass-energy or both?

 

[mfb]

Black holes suggest anti-matter has negative matter

They do not.

I think anti-matter has positive mass

That is the expectation of basically everyone.

But when 'explaining' evaporating black holes (e.g. https://en.wikipedia.org/wiki/Hawking_radiation#Overview)- matter [e.g. electron] and corresponding anti-matter [positron] are created out of 'the vacuum'

That is a problematic pop-science description, not the actual physics.
If an electron escapes, there is no positron involved at all.

 

[newjerseyrunner]

A virtual positron is not the same thing as a positron. Hawking radiation comes from virtual particle pairs, of which only one of which becomes a real particle.

 

[mfb]

Hawking radiation comes from virtual particle pairs

It does not. If you check the actual calculations, there is no virtual particle pair involved.