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do_white_holes_exist_and_if_they_do_can_we_see_them 2009/01/16 10:58 current
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 +**Do white holes exist and if they do can we see them?**
 +Thanks for the question.
 +For clarity, I'm assuming that you're taking the definition of a white
 +hole to be the one given here:
 +It was long thought that the laws of physics should be the same
 +whether time is running forward or backward.  That is, say you make a
 +movie of yourself gently tossing a ball up in the air and then
 +catching it.  Now play the movie backwards.  Does one look different
 +from the other?  Not really---the laws of physics in this case are the
 +same whether time is running forward or backward, so you can't easily
 +tell which movie is which.
 +Now, there's good evidence that black holes exist, so people thought
 +that there should be a "time reversal" of a black hole.  This object
 +would spit out matter into our universe.  That's the theoretical
 +justification for putting forward the idea of white holes.
 +However, white holes have never been observed.  Furthermore, there's
 +now good reason to think that the fundamental laws of physics are not
 +the same whether time is running forward or backward.  Therefore the
 +idea of white holes loses some of its theoretical justification.
 +For more about the whether the laws of physics are the same whether
 +time is running forward or backward, check out the second law of
 +thermodynamics and something called CP violation.  CP violation is
 +very interesting but unfortunately a very technical subject.  I
 +encourage you to do some reading about it but I can't go into it now.
do_white_holes_exist_and_if_they_do_can_we_see_them.txt · Last modified: 2009/01/16 10:58 by czars · [Old revisions]