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The Big Bang

  1. Sep 4, 2014 #1
    I am at the lowest level of the spectrum when it comes to this subject, but this has always raised some questions for me. If someone could answer a few of these I am almost positive it will just create more questions in the future, but I would still appreciate it. So here goes.

    1. I understand the concept that "nothing" existed before the big bang such as time etc. but does this mean that the big bang spontaneously created matter and if it didn't is that not proof something existed before it? Also is it even possible to create matter of any kind even a quark from nothing?
    2. Since the universe is of completely unknown proportions and we have to viable way to determine the "center" of the universe could the formation of new (insert cosmic body here) account for expansion?
    3. Is it very responsible of us to make theories based off of observations we collect from a sample size that we have no way in determining it's relation to the whole? Such as the estimated age of the universe; which from what I understand we gain a large portion of data from the oldest star we can observe but do so in knowledge that there very likely are stars older that we can not see.
     
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  3. Sep 4, 2014 #2

    Chronos

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    1] We do not know 'what', if anything, preceded the BB. Perhaps nothing, or perhaps an antecedent universe.
    2] The BB did not have a 'center', it happened everywhere at once.
    3] It is unlikely the universe has any stars that are more ancient than the universe.
     
  4. Sep 4, 2014 #3

    Bandersnatch

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    Here's some relevant materials for you to peruse:

    Re:1)
    It's a Lawrence Krauss' lecture at Gustavus Adolphus college. It's called "Universe from nothing". The man likes the idea very much, and is very vocal about it. The lecture presents it in layman's terms and Krauss is, as always, very eloquent and pleasant to listen to.

    The panel Q&A section starting at about 1:12:00 is, however, perhaps more indicative of the views of the scientific community at large, regarding the lecture's topic. It may also clear up what is meant by "nothing", and how it's not necessarily so nothing-ish.

    Re:2) http://www.mso.anu.edu.au/~charley/papers/LineweaverDavisSciAm.pdf
    Tamara Davis' and Charles Liveweaver's public outreach paper "Misconceptions about the Big Bang" should clear most of the commonly asked questions and straighten out misunderstandings about the theory.
    If you google for the authors, you'll get more, as well as more in-depth and technical papers on the subject.

    And just to cover all bases, this article: http://www.einstein-online.info/spotlights/big_bangs clears up another confusing aspect of the big bang, omitted by the previous one. Namely, the dual usage of the term.

    Re:3) In general, we only describe the observable universe. However, the application of the cosmological principle(i.e., the assumption that the universe beyond our reach is not radically different than what what we see) allows us to make some informed guesses about the whole.

    As for the age of the universe, it can be obtained by extrapolating the expansion back in time, as well as measured by a variety of methods(http://www.astro.ucla.edu/~wright/age.html). All of which are independent of what's going on outside our observable universe. That is, there might be parts of the universe we can't see that have different age(look up eternal inflation), but everything points to our local reality bubble being that old.

    Here's some more layman-oriented reading if you feel curious:
    http://www.talkorigins.org/faqs/astronomy/bigbang.html covers BB - what the theory actually says, what is the evidence, what are the objections etc.
    http://www.astro.ucla.edu/~wright/cosmology_faq.html - Ned Wright's cosmology tutorial. Apart from the FAQ, there is the actual tutorial(click through parts 1-4 on top of the page). A bit more demanding, but also more in-depth.

    Finally, on this forum there's the cosmology section with its FAQ and the pinned "effort to get us on the same page" thread.
    One of PF members, Mordred, compiled an overview post on universe geometry that might be worth reading:
    https://www.physicsforums.com/showpost.php?p=4406311&postcount=12
     
    Last edited by a moderator: Sep 25, 2014
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