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

Does universe pulse?

  1. Jan 11, 2010 #1
    Is that an official theory or just a light/naive guess (maybe mine)that, if after big bang everything expands, and we can be pretty sure every galactic center is a massive black hole -than galactics are"joining forces" to make it all(universe) back to the point the big bang happens again(and again,and again...)?
     
  2. jcsd
  3. Jan 11, 2010 #2

    sylas

    User Avatar
    Science Advisor

    This is not likely. The simplest and most straightforward implications of observations is that the expansion of the universe will continue indefinitely. Indeed, the expansion rate appears to be accelerating, and there's no known process to reverse that. The ΛCDM model (which is a kind of benchmark for models of the universe) has the expansion continuing for so unimaginably long that even super massive black holes would eventually "evaporate" away.

    This would take a long time... I calculate 4*1094 years for our own Milky Way's supermassive black hole, and trying to convey just how long that is defeats me. If every second of time since the Big Bang was blown out to be the entire age of the universe again, we still would have barely started on the way to durations like this.

    And the ΛCDM model continues on even after that, without end.

    There are some esoteric ideas for how this could get "turned around" somehow, but gravitation from existing matter can't do it, and putting it all into black holes doesn't change that. Something radically different from what we know of at present would have to be involved... and since it would be unexpected we cannot really expect it. The physics we have at present indicates an unending expansion.

    Cheers -- sylas
     
  4. Jan 11, 2010 #3
    Thank You sylas
    I understand than, that I cant really expect black holes to contain "anti-matter" or neither be build out of one...?
     
  5. Jan 11, 2010 #4

    sylas

    User Avatar
    Science Advisor

    My understanding is that black holes don't get decomposed into particles, so it makes no difference whether a hole is from compressed matter, or compressed anti-matter. As long as it has mass, the hole is the same.

    If you have a black hole, you can increase its mass just as easily by firing lumps of matter into it, or firing lumps of anti-matter into it, or even both at the same time -- but from different directions so you don't have to manage big explosions from matter and anti-matter bumping into each other before crossing the horizon.

    The hole doesn't care; it is the ultimate omnivore.

    Cheers -- sylas
     
  6. Jan 11, 2010 #5
    What is your opinion of black holes as possible wormwholes inbetween parallel universes (and its existence itself) ?
     
  7. Jan 11, 2010 #6
    Exactly, and even if matter-antimatter is undergoing annihilation in a black hole, resulting photons are not going anywhere.
     
  8. Jan 11, 2010 #7

    sylas

    User Avatar
    Science Advisor

    In my opinion it is too speculative to be worth anything much, and I don't think it could apply even in the most speculative forms for black holes formed by collapse of matter, which is how we get black holes. The terms "parallel universe" and "existence itself" are not well defined.

    You can have fun and games with general relativity and strange spacetimes that have weird interconnections, but there's little value in it unless you are one of the few people who understand general relativity well enough to deal with the mathematical descriptions of such things. I'm not at that level.

    In any case, even given the possibility of such spacetime oddities, there's no expectation that this is what happens when you throw enough mass together and make a black hole.

    Cheers -- sylas
     
    Last edited: Jan 12, 2010
  9. Jan 12, 2010 #8
    Thanks
    I think you are right.It is too speculative to be worth much.I was thinking about possibility of traveling through wormholes to spare time . I've heard about level one parallel universes and probably mixed up some ideas I shouldn't have... :-))
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook