Smallest stable black-holes

[Boerseun]

Like Jay said, antimatter has exactly the same mass-gravity property as normal matter. Besides, if anti-matter were gravitationally repulsive, they would never fall together to fall a black hole in the first place.

Originally Posted by Jay-qu

Black holes are only thought to carry a few basic properties: mass, charge and entropy. From this understanding it seems that the 'information' of the matter being either matter or antimatter is lost.

I'm not completely with you here. As far as I know, the only difference between matter and antimatter is that the charges are reversed. Electrons are positive in antimatter, and protons negative. If black holes only have mass, charge and entropy, then an antimatter black hole should be able to annihilate a matter black hole? Seeing as the only difference between the two is charge, and that's a property retained by a black hole?

So if they collide, first off the event horizons should merge around the common center of mass as the two approach, which should result in a (viewed from outside the common even horizon) mutual black hole with an even horizon looking more like a figure eight, or the infinity sign, which will again approach a sphere as the two meet up, upon which the even horizon would suddenly shrink as the mass is annihilated?

This is indeed very interesting, and definitely worthy of its own thread. (Sorry for thread-jackin', by the way)

[freeztar]

The question of AMBH vs. MBH annihilating was answered here by an Astronomer.

Curious About Astronomy: What happens when an antimatter black hole collides with a matter blackhole?

[Boerseun]

Originally Posted by freeztar

The question of AMBH vs. MBH annihilating was answered here by an Astronomer.

Curious About Astronomy: What happens when an antimatter black hole collides with a matter blackhole?

That guy said the same thing Jay said - also about the only things to be measured being just the mass, charge and angular momentum.

And my question remains the same - with the difference between matter and anti-matter merely being reversed charge, that is a property that will be retained by an anti-matter black hole?

[freeztar]

It would seem to me that a collision would cause anhilation which would produce lots of gamma rays. These gamma rays would be unable to escape and would be trapped. So, in essence, the resultant mass should simply be the mass of BH#1 plus BH#2. But that's just a guess.

[Boerseun]

This raises some awesome possibilities:

Say, for instance, the mass required for black hole formation is x. The MBH is 100x, and the AMBH is also 100x. Then the gamma burst would be trapped underneath the event horizon, until the resultant mass (after annihilation) reaches lower than that required for black hole formation, upon which all that gamma radiation would be released at once. That, ladies and gentlemen, would just be friggin' awesome...

You'd basically see a combined event horizon shrinking and shrinking and shrinking and then all hell breaks loose as the total energy of 200x is released at the same moment...

[modest]

Originally Posted by Boerseun

This raises some awesome possibilities:

Say, for instance, the mass required for black hole formation is x. The MBH is 100x, and the AMBH is also 100x. Then the gamma burst would be trapped underneath the event horizon, until the resultant mass (after annihilation) reaches lower than that required for black hole formation

The photons that result from the annihilation have equal energy to the matter / antimatter before the annihilation. It's the energy which curves spacetime rather than just the rest mass and photons do have energy.

If you could enclose a hydrogen bomb in an impervious and infinitely strong box, the box would curve spacetime equally before and after the bomb in the box exploded. Before it exploded the box would contain mostly hydrogen and after the explosion it would have mostly photons, but the total energy of the box would be the same.

~modest

[Hasanuddin]

Hi folks,

A new thread has been started to address and discuss the nature of AMBH

Originally Posted by Hasanuddin

...

I wholeheartedly agree with:

Originally Posted by Beorseun

This is indeed very interesting, and definitely worthy of its own thread. (Sorry for thread-jackin', by the way)

I have no problem that several interesting lines of discussion have been opened. However, I want to stay focused (and I'm keenly interested in CraigD's response, and if anyone wishes to join the discussion of how/what could achieve the smallest stable black-hole.

[Jay-qu]

Originally Posted by Boerseun

Like Jay said, antimatter has exactly the same mass-gravity property as normal matter. Besides, if anti-matter were gravitationally repulsive, they would never fall together to fall a black hole in the first place.

I'm not completely with you here. As far as I know, the only difference between matter and antimatter is that the charges are reversed. Electrons are positive in antimatter, and protons negative. If black holes only have mass, charge and entropy, then an antimatter black hole should be able to annihilate a matter black hole? Seeing as the only difference between the two is charge, and that's a property retained by a black hole?

Matter has the opposite charges to normal matter, charges are quantum numbers - the electric charge is the most physically accessible quantum number to our intellect. Other charges are also reversed when swapping from matter to antimatter.

Let me spell this out a little bit: Black holes will suck in all sorts of matter like electrons and protons, if it sucks in more electrons the black hole will have a net negative charge. An antimatter black hole may have sucked in positrons and negatrons, if it sucked in more positrons the black hole will have a net positive charge. These two black holes with opposing charges would attract each other - but this does not mean they annihilate when they collide, as a black hole made of electrons and one made of protons certainly wouldnt annihilate.

There is a slight hole in my argument. Black holes are said to destroy information, ie they only keep the bare minimum of information of what they have sucked in. This stops our conservation laws from been violated: the black hole must at least take on the basic quantum numbers of the particles it sucks in. But this is conjecture on my part as the no-hair theorem states only electrical charge is conserved.

Im not sure if I am getting any closer to answering peoples questions or not.. so I will stop here for the moment.

[modest]

Jay-qu, would this be consistent with GR?:

Originally Posted by modest

If you could enclose a hydrogen bomb in an impervious and infinitely strong box, the box would curve spacetime equally before and after the bomb in the box exploded. Before it exploded the box would contain mostly hydrogen and after the explosion it would have mostly photons, but the total energy of the box would be the same.

I'm thinking that it isn't so much mass that curves spacetime, but energy (stress & momentum not being a factor here). Since energy is conserved in an annihilation, whatever matter / antimatter annihilations happen behind a horizon would not affect the gravitational field. I'm curious if this makes sense to you.

~modest

EDIT: Sorry Hasanuddin, I didn't realize I should have posted this in the other thread. My bad.

[Jay-qu]

Yes Modest, that is correct. People often misinterpret Einstein's famous equation E=mc^2 ( or E^2=(mc^2)^2+(pc)^2 for those familiar with the full equation) as showing how mass and energy can be converted back and forth. Really it is showing a deeper equivalence, they are but the same thing only in different forms. So yes energy bends space just as mass does.