I saw a documentary recently about the possibility of time travel and they mentioned that Space and time are connected, I remembered how if you go towards a black whole time slows down because the object is so dense. Then I got thinking about what would happen if the object was instead really light, but matter can't be light because it has weight, maybe antimatter does not work either in this case. But anyhow that just got me thinking about antimatter Black holes in general, we often don't think of such a thing because there is more matter than antimatter out there. SO let's use this space to consider how an antimatter black hole would behave.
Negative Mass Black hole, that sounds about right for what I originally had in mind, phenomenon caused by the collapse of negative mass stars. All hypothetical of course.
There is no reason to expect an antimatter black hole to behave any different than a any other black hole. Antimatter isn't expected to act any differently as far as gravity is concerned than regular matter.
Just to add to that a bit: antimatter particles don't have negative mass, or anything like that. A positron (anti-electron) has exactly the same mass an electron, for example. So, a black hole made of positrons would behave gravitationally just like a black hole made of electrons.
1) Black holes can't be matter or antimatter. They are singularities, not physical objects. 2) The sort of object that exists when a stellar remnant is _just_ too small to create a black hole (a neutron star) is made of neutrons, and thus is not matter or antimatter. So the question doesn't really have any meaning. Black holes cannot be antimatter, nor do objects like them.
To be quite fair, the actual existence of a singularity at the center of a black hole is not a confirmed fact. But the mere existence of the event horizon would keep us from distinguishing from the BH formed by antimatter or matter even without a singularity. There are theoretically such things as antineutrons (made up of antiquarks.). In addition, The outer layer of a neutron star are is likely just highly compacted atomic nuclei. Of course, that doesn't mean that should expect to find anti-neutron stars, as there is no evidence that anti-matter exists in the quantities required.
That is not correct is it. It is only for a distant observer that this applies. For the infalling observer time is measured in the same way and nothing remarkable happens, Is antimatter allowed to become a large cluster?What happens if such an object falls into a "normal" Black Hole? Might there be there any unusual reaction? Don't matter and anti-matter self anihilhate?
Yes. Theoretically, there could be stars - even whole galaxies - out there made entirely of antimatter. We would not know it.* Photons from antimatter are identical to photons from matter. *except that they would shine like lighthouses in the gamma spectrum, as they plowed through all the surrounding normal matter Matter an antimatter annihilate and release their energy in the form of very energetic EM, such as gamma rays. Since no forms of EM can escape the event horizon of a BH, there is no effective difference in how infalling anti-matter would affect it.
