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Can Flat Space Experiments simulate the Big Bang?

  1. Mar 29, 2010 #1
    I'm wondering, now that the universe has expanded and is now pretty much flat, can any experiment we do tell us what might have happened during the Big Bang, when the universe was still small and tightly curved? It doesn't sound like the same situation. The results we get today travel meters or inches to the detectors, which is still very large compared to the very early universe. Would the same things result in a universe that is tightly curled up? If not, how far back can we go before we are no longer comparing apples to apples? Thanks.
  2. jcsd
  3. Apr 2, 2010 #2
    I don't personally think any experiments we can do today are especially hindered because the universe is flat. If it were tightly wound up like early in the universe at the big bang so far it appears nothing we know can exist.

    There are lots more obstacles to creating a big bang than flat spacetime. The biggest obstacle is that no one knows or even has a theory about what the big bang is...only theories about what happened once it started...we even know is space and time were 'observables' at the start (whether they were separate entities or not).

    Another way to ask your question is "Can we produce singularities" or can we observe them...so far the answer seems "no",,,but perhaps tiny black holes will be within our experimental capability....but whether we can observe what's inside the horizon is one of those "obstacles".

    There is an active thread currently about rips and tears spacetime ....they MIGHT be such that that are similar to a big bang or black hole singularity...nobody knows if they exist...

    Last edited: Apr 2, 2010
  4. Apr 3, 2010 #3
    So what I guess I'm asking is at what size of the universe is particle physics relevant? Is particle physics, even in it virtual form, relevant all the way back to the singularity? I'm wondering if the flatness of present spacetime have some influence on the type of particles we can possibly see. Does spacetime symmetries determine particle properties, conservation laws, speed of light, gravitational constants, etc?
  5. Apr 4, 2010 #4


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    I think the confusion is caused by "LHC simulates big bang" or something like that.

    One could say that it's possible to get a little closer to the big bang, but if you compare the LHC center-of-mass energy of (currently) 7 TeV with the Planck energy you will find that it's still a long way to go :-)

    O know a very crude estimation in the context of LQC which shows that QG effects become small at approx. 100 * Planck length. That means that with the LHC we come closer to the big bang, but we are still in domain where flat space and classical relativity do apply.
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