Distunguishing matter/antimatter black holes

Mu naught

I don't mean to hi-jack the thread, but would ordinary matter be distinguishable from anit-matter?

For example - say we were looking at a galaxy a few billion light years away, composed of the same basic elements only in their anti-matter form. Would there be any way to know it was different?

haael

Baryon number minus lepton number.

A basic question: do you believe that gravity and electromagnetism can somehow describe ALL physics? Is there no need for any other interaction?
If you would say no, black holes will remember some conserved charge associated to the new interaction.
I don't know if it is B-L or something. Maybe we already know this charge (say weak hypercharge), or maybe there is something more fundamental.

However, black holes definitely will have to remember something more than electric charge and mass. Unless gravity+EM is everything we have in our universe.
Maybe this additional "something" would distinguish between matter and antimatter.

filegraphy

the antimatter has reverse polarity inside the atom, so could we detect it?

Superstring

If you are unable to differentiate between the two, would that infer information is lost?

filegraphy

Now that I think about, antimatter has reverse polarity, so could we tell?

Patrus89

I don't see how a black hole by definition could be "anti" or not as the case may be. There is no clear definition of matter once it has been crushed passed degeneracy pressures into whatever is within the event horizon.

What you could detect is the annihilation of infalling matter and antimatter in the accretion disc. You would need as much anti-matter as matter to form a black hole of a given mass, and that had to come from somewhere. On the boundary of that region of anti-matter and our "normal" region, there would be annihilation which should be detectable. AFAIK this has not been detected. For this hypothetical black hole to be detectable it would require infalling matter or antimatter, and then we're back to the bigger question of antimatter regions that have not been observed.

Beyond that, I cannot think how you would be able to tell from the emission spectra of a BH what it was at any previous time. The charge can change over time based on what the hole eats, so how to know its initial conditions?