Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Anti matter black hole

  1. May 24, 2015 #1
    Dear PF Forum,
    In less than 1 second after big bang, baryons were created. And there's asymmetry in it.
    Can anyone help me?

    1. Is it physically possible for a galaxy made entirely from anti matter?
    2. If it's true, is it statistically possible for a galaxy made entirely from anti matter?
    If it's true, then I'd like to know the answer question here.
    No information can come out black hole.
    Only their mass, and with it their gravity.
    3. Is it possible for us to tell that this black hole originator is matter or anti matter?
    Or you guys scientist just say, well No information can come out black hole. So we don't know :smile:
    4. Does "matter" black hole differ from "anti matter" black hole? If question number 3 is true.
    5. If question number 4, what if we throw an anti matter black hole to a matter black hole?
    A. Will they explode?
    B. Will they gets bigger. By "bigger" I mean their schwarzshild radius, of course its size is always zero if it's a singularity. Because, by logic. The explosion will generate more energy
    E = (m(Matter Black Hole) + m(Anti matter black hole)) x c2
    And this E will eventualy become m, right?
    m = E/c2
    But where is this m come from? Matter? Anti matter?
    I just want to know if my logic in question 5 is right.
    Consider this:
    A star, 1 solar mass comes from the north of our sun and hit our sun.
    What happen? Okay...., there's blast. Earth are surely destryoed.
    Solar system is destroyed, some TNO might survive.

    So what I'd like to know is,
    What if a matter+anti matter black hole collide?
    Will it explode like the sun, or will it getting bigger?

    But first of all we must be sure that
    Anti matter galaxy is physically possible, statistically possible, matter and anti matter black hole is different and ... they collide.

    Thanks for any answer.
  2. jcsd
  3. May 24, 2015 #2

    Simon Bridge

    User Avatar
    Science Advisor
    Homework Helper

    Yes. There is nothing in principle preventing an antimatter galaxy ... though we would expect that the same mechanism that gives the local assymetry about us would make a whole antimatter galaxy very unlikely.

    That would follow from the above - unless you choose a model where the antimatter doesn't survive in large enough conglomerations.
    To work out the statistics would be problematical at best.


    No. (Follows from 3 - included for completeness.)
    In principle - yes.
    You are thinking of an antimatter-matter annihilation ... that is a "yes and no". The mass-energy gets combined to one object. It does not matter if the matter and antimatter inside annihilates or not, the resulting energy cannot escape.
    Yes. When two black holes gobble each other, they get bigger.
    There is no useful distinction to be made between energy and mass. They are the same thing - this is what ##E=mc^2## means.
    You end up with one bigger black hole.

    Galaxy is not a single object - and you have shifted from black holes to stars. The result would be much like what happens when regular matter galaxies collide only with more energetic parts when matter/antmatter stars collide. This is now highly speculative - we can address it here in terms of the light it sheds on current models of matter and gravitation.

    Bottom line: If you chuck antimatter into a black hole, the antimatter joins the "singularity" as positive energy - increasing the mass of the black hole. Same if you chuck matter into an antimatter black hole. In GR there is no distinction to be made between energy and mass - it all goes into the stress-energy tensor.

    You are starting to approach concepts which require a better framework than the one you have. See:
    http://preposterousuniverse.com/grnotes/grtinypdf.pdf [Broken]
    Last edited by a moderator: May 7, 2017
  4. May 24, 2015 #3
    Thank you very much Simon Bridge for answering each question.

  5. May 25, 2015 #4


    User Avatar
    Gold Member

    Black Holes don't have matter to collide... It's vacuum up to the singularity... Even if you have matter/antimatter annihilation there - resulting in other particles- those particles can't escape...
    Yet it's not certain if you can talk about particle interactions in a black hole as you do in our everyday experience of particle physics..
  6. May 25, 2015 #5
    And the size of this singularity is... 0 cm? or 0 km?:smile:
  7. May 25, 2015 #6


    User Avatar
    Gold Member

  8. May 25, 2015 #7


    User Avatar
    Gold Member

    The singularity is a point...
  9. May 25, 2015 #8
    Yes, yes I know. It's just a pun.
    So, they say no information comes out of black hole.
    They say that gravity propagates at the speed of one of the 4 forces, electromagnetic force.
    And the only information that we can get from black hole is it's mass?
    Light can't escape black hole, while gravity which propagates at the speed of light can escape?
  10. May 25, 2015 #9
    I'm sorry did you say/type a point in 4D? And when I hit reply the 4D is disappear.
    Is it really something from 4D?
    I imagine a flat paper in 2 dimension and we somehow penetrate a cone and what they see in 2D is a circle/hyperbole/parabole/ellips and perhaps just a point.
    Is it like that for a black hole?. A 4D object enters 3D space? Or it's just
    and you correct your error?

    Thanks for your trouble to answer me Chris.
  11. May 25, 2015 #10


    User Avatar
    Gold Member

    In fact I think I should correct it even further and drop the notion of a point out of this conversation... the singularity is not even part of your spacetime.
  12. May 25, 2015 #11


    User Avatar
    Gold Member

    As for the gravity escaping, I don't think there is any kind of escape from the BH... It's how the geometry of your spacetime looks like when you are trying to solve the Schwarczhild metric's in Einstein Field Equations.
  13. May 25, 2015 #12


    Staff: Mentor

    Neither. See below.

    Not really. Strictly speaking, it's not part of spacetime at all, as you say later on. But you can take the limit as ##r \rightarrow 0## of the set of all points in the spacetime at the same ##r##. The limit of this set is not a point; it's a spacelike line (the limit of an infinite set of 2-spheres as the radius of the 2-spheres goes to zero).

    It doesn't have to. See this Usenet Physics FAQ article:

  14. May 25, 2015 #13
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook