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Quantum Gravity and time's arrow

  1. Jun 24, 2009 #1
    So, a couple weeks ago I read this article. I came here, expecting that someone would probably talk about it (I've been viewing posts here for a while, but became a member only recently). No one, that I could find, has actually talked about it, so I though it would be a good first post for me :). Here's the actual http://arstechnica.com/science/news...-everything-by-ditching-tenet-of-physics.ars" to the article which talks about two papers that utilize the recent finding of space-time behaving as if it has two dimensions at small scales. This allows space to be 1 dimension and time is the other. When you do this, space is the same along all paths, but time isn't (I don't know why, and can't read the actual papers).

    This got me thinking about what I was thinking when I first read Brian Greene's "The Fabric of the Cosmos," why does anyone assume that time should be the same forward and backward? Have we ever observed it to be so? I will agree that there are times when it is possible to take a small slice of space-time and not be able to tell the difference forward or backward in time. Like watching a fan move, you wouldn't necessarily know which way time was pointing initially. But this isn't true of all of space-time, space is, but it certainly isn't the same when you put time in there. It seems to me like a way of sticking to classical physics where everything is just a bit easier.

    I'm no physicist, actually really just getting started in my physics education, and I'm only going to minor in it, so I don't really know how many people assume that time should be the same both ways. That is something that Brian Greene posited in that book though, and it just struck me as odd, since science is supposed to be used to explain observations and I've never heard of anyone observing that. Perhaps I just misunderstood what he was trying to say, but I just had to ask to make sure.
     
    Last edited by a moderator: Apr 24, 2017
  2. jcsd
  3. Jun 24, 2009 #2

    cristo

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  4. Jun 24, 2009 #3
    Wow, can't believe I missed that... sorry. Thanks!
     
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