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Imperfections in perfection? Big bang

  1. Jan 11, 2009 #1
    I'm not as well read on big bang theory as some of you, but I have spent a lot of time wondering about some of the comments used to describe it in the media or education. A lot of them describe it as being a single, immeasurably small, finite point and being composed of pure energy. String theory then says maybe it's not immeasurably small and we have a dimension (or more) in this nothingness.

    As the universe expands, energy condenses into mass - particles, nuclei, atoms, molecules, planets...

    But for this to happen, one would have to assume that either the energy began expanding in a none uniform manner, or it expanded into a none uniform space.

    It's easy to look at things like Brownian motion now and say random, but it obviously isn't, it obeys very basic rules and it's scale is what makes the results hard to predict.

    Those initial collisions that produced the condensation of energy can only have occurred if none uniform patches emerged as it expanded.

    Supposing the energy emitted from this singularity moves out in the fashion of a Maxwell Boltzman curve, I can see how that may be possible, with a spectrum of energies being emitted from the point you have variation.

    Or this finite point was not perfectly uniform to begin with perhaps.

    I can fully appreciate how a minute variation at the big bang could snowball into a star system. But that variation has to exist for that to happen - you can't snowball something without rolling a smaller snowball first.

    I find it believable that the universe has been expanding and collapsing for quite a while and that it does not fully collapse, it merely does so to a point that it becomes unstable enough that it re-expands in a perfectly lossless fashion. Although, that does not do much to answer the origination of variance problem.

    I was thinking about this while I was also thinking about evolution, that an ability to reproduce does nothing without a factor of variation. Genetic evolution plays the idea out for what would normally be thought of as life, but I thought it was interesting to apply it to a more universal concept. An ability to expand a gigantic amount of energy alone does not explain the variation - the universe should be a homogenous, lower energy clone of the singularity if this variation wasn't there at the start. I found it interesting to consider this in regards to biology, that students are told variation is random and later that maybe some elements effect this, so it's not entirely random. But I began wondering how far back you could pull the causes of what is now considered random - in terms of our DNA and our own perceptions, which are based on the physical world. We understand so many of the laws governing interactions, what is beyond is us is the observational and computational ability to sequence them all together to explain why a particular DNA strand mutated - but ultimately, it's a certainty from a long, long, long way back. There are, as I understand the universe, absolutely no entirely random events - which conversely means everything is predictable. This got a bit close to a religious experience in thinking, so I simply kept wondering, so where has this uniqueness originated from, is there one or more scientific explanations for the source of it.

    The most rooted I can get this question is, why did the big bang expand in a none uniform manner?
    Last edited: Jan 11, 2009
  2. jcsd
  3. Jan 11, 2009 #2

    Initial universe could be perfectly symmetric. But as QM includes randomness (in Copenhagen interpretation, in MWI it is different but the observable result is the same) a symmetrical system can lose symmetry at some point and become assymetric.

    These tiny quantum fluctuations had been amplified by the Dark matter for about 10**5 years, so we see tiny differences in the cosmic microwave background.
  4. Jan 11, 2009 #3
    I dislike the uncertainty principle for explaining this on the grounds that it's discussing the idea of taking a measurement now and knowing a pair of canonically joined variables simultaneously. Thus creating a degree of randomness in one of those variables, as measurement of one relies on expansion of another.

    This is not the same as saying, if this particle starts out with this finite velocity, travels for this finite time and has this finite mass, what is it's momentum and position? The first is our inability to measure now the event is occurring, the second is the 'reality' of what the particle is experiencing.

    Is quantum spin state not merely an expansion on that same idea?

    As I understand, we can't determine a quantum spin state without measurement because we don't have the information to predict the spin state - not because it is actually random.

    This is would seem to be an observational problem as opposed to an actual random behavior.

    Last edited: Jan 11, 2009
  5. Jan 11, 2009 #4
    Please check the QM forum.
    There is no hope that 'it is just a measurement problem' - check the Bell's theorem.

    But there is a choice. Some people believe that nature is random. Others, like me, believe that QM is deterministic - but deterministic interpretation of QM requires that you accept the Many-Worlds interpretation (which might be even a bigger challenge). It is up to you.

    In any case 'I dislike' does not work in physics :)
  6. Jan 11, 2009 #5
    Just wanted to comment on this; I would argue that it, in fact, does work. Physicists should have some belief in what they think is right. If physicists have no convictions, what are they working for? All the great experiments and theories have come from physicists trying to prove their conception of the Universe correct. This is not to say that we should ignore results that don't fall in line with what we believe; we should all be like Michelson, and do things we believe in but publish the results regardless of whether the conclusion is what our hypothesis originally was.

    Much of the reason people work on loop quantum as opposed to string theories is because they dislike the idea of how strings work, and strings being fundamental, and like the idea of a finite, quantized space. If they end up being correct, that will have been yet another thing in support of the idea that 'I dislike' is important. Also, with so many interpretations of QM, as you even hinted at yourself, with no hint as to which is correct, I think liking one of them and working on it is a useful approach. Much of the contribution to science in general would be lost if everyone worked on the "popular" theory alone.

    I know it's a bit off topic, but...
  7. Jan 12, 2009 #6
    Yes, you're right, I was mostly replying to those wo 'dislike' QM in general
  8. Jan 12, 2009 #7
    You have many too many thoughts to comment upon very many.

    Randomness has its own set of rules;probabilities. The very existance of randomness suggests that things will NOT always be perfectly uniform all the time. In QM for example everything that can happen WILL happen, maybe not very frequently, but it will occur. Hence quantum tunneling results in radioactivity!!! Who would have "thunk' that a hundred years ago??

    The opposite is apparently true....nothing is precisely predictable according to QM....that's why it drove Einstein "nuts", "God does not play dice." he said...but according to the uncertaintly principle we can't predict nor measure with absolute cetaintly.
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