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So , we don't know how universe began?

  1. Oct 20, 2007 #1
  2. jcsd
  3. Oct 20, 2007 #2
    Well, there is the Big Bang Theory, but it's a theory, and I don't know a lot about it, so we don't have solid proof as to how(or why?) the universe was created.
     
  4. Oct 20, 2007 #3

    Hurkyl

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    BBT isn't 'just a theory'; it's quite well substantiated. But contrary to popular belief, it doesn't say anything about the origin of the universe.
     
  5. Oct 21, 2007 #4

    Chronos

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    I second Hurkyl's motion. BBT excels at explaining how the universe evolved from an incredibly hot, dense volume about 13.7 billion earth-time years ago. But, it is silent on the 'origin' of that volume. It also does not assert the universe is finite in age or size, merely the observationally accessible slice. The 'universe' could be infinitely old and spacious, but the observable universe is clearly finite. This distinction is a frequent source of confusion. Unless otherwise specifically stated, cosmologists mean the observable slice when using the term universe. It is however possible unobserved regions exert observable effects in our universe. It is also possible to mathematically model events beyond the observational cutoff [e.g., Martin Reuter's 'bounce' and Sean Carroll's 'Universe From Nothing]. Unsurprisingly enough, testing these ideas is astonishingly difficult. Our own minds are, of course finite, and that poses the ultimate limit on our ability to comprehend the 'big picture'. I'm convinced we will never know with certainty how the universe originated. And I find that notion strangely comforting, for it means science is a journey without end. In that sense, the universe IS truly infinite.
     
  6. Oct 21, 2007 #5
    I am always skeptical that scientists can really know as much as they claim about the Big Bang. And i am often surprised as to how confidently astronomers base their work on something that is still a hypothesis. It is a hypothesis which we have very good evidence to believe, but we must remember that we are predicting something that happened a heck of a long time ago, so being sure of anything much about it is very hard. If the attributes that we interpret to be due to the big bang turn out to be showing us something different, the whole foundation of astronomy will have to be changed. I would prefer it if astronomy ignored the BB and just progressed on the data we are absolutely sure of, instead of woking backwards from an unproveable hypothesis. I am not saying the BB theory is wrong, i just get the impression that people belive that the BB theory has been proved as the beggining of the universe, ie, the everything out of nothing idea. But there could be alternative interpretations of the data that has lead us to beleive in the big bang.

    I cant see what so wrong with just saying we dont know exactly how the universe began yet, that seems to be the impression i get from most big bang material.
     
  7. Oct 21, 2007 #6

    Hurkyl

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    I'm pretty sure that scientists know almost exactly what they claim to know about the big bang -- and very little of what popular media claims scientists know.

    For example, despite popular belief, the big bang theory doesn't say anything about the origin of the universe. (Didn't I just say that? :grumpy:)

    The current 'era' of the observable universe started with the big bang, but BBT makes no speculation about what, if anything, there was before the big bang.
     
    Last edited: Oct 21, 2007
  8. Oct 21, 2007 #7

    DaveC426913

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    Our understadning of the universe is pretty good all the way up until a tiny fraqction of a second before the event. While we don't know quite what happened in that last nano-second, we have no reason to believe there's anything wrong with our understanding the of next 13.69999999999billion years, 364 days, 23 hours, 59 minutes, 59.999999999 seconds following it.

    It is not a hypothesis; it is a theory. An extremely well-substantiated one.

    They believe that because the unwashed masses like cut-and-dry answers. Too bad for them.

    There could be, yes. And many have proposed them, and technically, they are all given due process. And the Bgi Bang Theory has come out by far the winner every time. No other theory even comes close to matching the evidence.

    That doesn't mean it won the race, it just means we bet where we see a winner. So far, it's been an excellent bet.

    That's what we say, yes.
    Choose your material more wisely. For example there's a Physics Forum where you can ask experts who will give you much more accurate answers than the stuff you might read about in pop books or hear about on pop TV.
     
  9. Oct 21, 2007 #8
    Thats what i find unlikely. I doubt that working that out to that many significant figures is accurate.

    I would agree with all of your other points in the above post, but my problems with BBT are more specific. I will post them if they are suitable for this topic, but i feel we are deviating from the OP which was specifically asking about the time before the Big Bang, how the universe was originally created. The best current explanation has been advanced from Dr. Martin Bojowald with his Loop Quantum Gravity, but this remains a very mathematical theory and does not really explain the Everything-From-Nothing problem.
     
    Last edited: Oct 21, 2007
  10. Oct 22, 2007 #9

    Chronos

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    'Nothing' reasonably approximates what preceeded the first tick of planck time.
     
  11. Oct 22, 2007 #10
    http://xxx.lanl.gov/PS_cache/arxiv/pdf/0704/0704.0908v2.pdf

    I hate to play the role of the skeptic, but it has recently been discovered that your "extremely well-substantiated" theory has a giant gaping hole in it that defies all the odds of a typical Lambda-CDM theory. Besides the fact that Lambda-CDM theory is based on three different metaphysical (physically undefined) entities, inflation, dark matter and dark energy, it quite spectacularly failed one of the key testable "predictions" that it made. In most scientific circles, those kinds of odds against finding such a gaping hole in what is supposed to be a relatively homogeneous mass layout would be evidence enough to scrap the theory, or at least evidence that the theory still needs quite a lot of work.

    If our understanding of the origins of our universe was "pretty good" as you claimed, then the size of that hole would not have defied the "predictions" of the theory in such a spectacular fashion.
     
  12. Oct 22, 2007 #11
    Good observation. The point i was trying to make in the above post is that i have no problem with scientists coming up with theories like the BBT, as that is currently the most likely theory, but i cant understand why anyone who questions the theory is labelled a crank. They act as if BBT is definitively proved beyond any doubt. To me it seems common sense to say 'we dont know exactly how the BB happened because that is very hard to know precisely as it happened so long ago' but instead we seem to get scientists convinced that BBT is 100% correct, and seem to think we can base all other branches of cosmology on this theory. To save me ranting about this (which i am sure is not welcome on this forum), i'll copy a small bit of a letter which I found online, written to the scientific community, from over 500 separate scientists, which is about not working backwards from BBT and instead progressing forwards without the constraints the Big Bang puts on alternative theories. It can be seen at http://cosmologystatement.org/


    "The big bang today relies on a growing number of hypothetical entities, things that we have never observed-- inflation, dark matter and dark energy are the most prominent examples. Without them, there would be a fatal contradiction between the observations made by astronomers and the predictions of the big bang theory. In no other field of physics would this continual recourse to new hypothetical objects be accepted as a way of bridging the gap between theory and observation. It would, at the least, raise serious questions about the validity of the underlying theory.

    But the big bang theory can't survive without these fudge factors. Without the hypothetical inflation field, the big bang does not predict the smooth, isotropic cosmic background radiation that is observed, because there would be no way for parts of the universe that are now more than a few degrees away in the sky to come to the same temperature and thus emit the same amount of microwave radiation.

    Without some kind of dark matter, unlike any that we have observed on Earth despite 20 years of experiments, big-bang theory makes contradictory predictions for the density of matter in the universe. Inflation requires a density 20 times larger than that implied by big bang nucleosynthesis, the theory's explanation of the origin of the light elements. And without dark energy, the theory predicts that the universe is only about 8 billion years old, which is billions of years younger than the age of many stars in our galaxy.

    Even observations are now interpreted through this biased filter, judged right or wrong depending on whether or not they support the big bang. So discordant data on red shifts, lithium and helium abundances, and galaxy distribution, among other topics, are ignored or ridiculed. This reflects a growing dogmatic mindset that is alien to the spirit of free scientific inquiry.

    Today, virtually all financial and experimental resources in cosmology are devoted to big bang related studies. Funding comes from only a few sources, and all the peer-review committees that control them are dominated by supporters of the big bang. As a result, the dominance of the big bang within the field has become self-sustaining, irrespective of the scientific validity of the theory.

    Giving support only to projects within the big bang framework undermines a fundamental element of the scientific method -- the constant testing of theory against observation. Such a restriction makes unbiased discussion and research impossible. To redress this, we urge those agencies that fund work in cosmology to set aside a significant fraction of their funding for investigations into alternative theories and observational contradictions of the big bang. Allocating funding to investigations into the big bang's validity, and its alternatives, would allow the scientific process to determine our most accurate model of the history of the universe.
    "


    Personally, I think that they all have a point.
     
  13. Oct 22, 2007 #12

    cristo

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    If one questions the theory on an internet forum, without any substantiating evidence, then it is most likely that they are a crank. However, if a scientist publishes a paper questioning a certain point, then they will most likely be taken more seriously. Such is the nature of the internet, there are many people who go around trying to condemn well established theories, that this forum does not put up with cranks.

    Who is this mysterious "they" of which you talk? You've just given a list of people who don't act like this. Futhermore, I know of no working cosmologists who say that the Big Bang theory is 100% accurate; that's a stupid thing for anyone to believe. However, for the moment, it is the most accurate theory we have (as has been stated a few times in this post and more times than I can count on this forum!)

    Who are these scientists? Do you have any references?
     
  14. Oct 22, 2007 #13

    DaveC426913

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    Of course. What are you expecting? That a theory wil be born, whole and unsullied by modification in one fell swoop? Theories take decades, if not much longer, to refine.


    I really think you're tilting at windmills here. No educated, reputable person is claiming that we have all the answers about the origin of the universe.

    Perhaps what you need to do is go out and find some people who are claiming that, and take it up with them...
     
  15. Oct 22, 2007 #14
    There are many people who doubt the big bang that are definately not cranks, the list of 500 scientists in that list i gave should show that. I am not trying to show that BBT is wrong in any way, as i said before, it is currently the best theory to account for the observations we see. However i do have a problem with using the BB as a basis for nearly all other aspects of cosmology. Because the BBT is so important to cosmology it is unlikely that scientists will be willing to significantly change BBT if new observations come along, as vast areas of cosmology would have to changed aswell. There are plenty of peer reviewed materials that offer alternative ideas to mainstream BBT, they offer different interpretations of the formation of the universe and galactic structures than are currently unaccepted by the Big Bang (gravity based) model. Sadly SpaceTiger has informed me they are not suitable for this forum, so i try to refrain from posting them here.

    I was referring to the popular misconception that the Big Bang solves the mystery of the origin of the universe, when infact it does nothing of the sort (i'm sure you are aware of that). By 'they' i was refferring to the mainstream cosmological opinion that the big bang is not worth debating any more (as SpaceTiger told me here "The BBT is no longer debated in mainstream science, so it would be inappropriate to debate it here.") Well i feel that everything in science should be open to debate, especially a theory that forms the core base of modern cosmology and especially one where over 500 scientists feel the need to look for alternatives.

    Most mainstream cosmologists. Ok, i should not have said 100%, but scientists do say they are 99% of BBT, which i think is unlikely as it is an event that happened so long ago misinterpretation of data would be very easy. We can predict (for example) what the level of the sea was 1000 years ago to roughly 90% accuracy from geophysical data, so guesssing what the entire universe was like over 13.7 Billion years ago, to 99% accuracy, seems a stretch to me. In a nutshell i just think that cosmology should consider the viable alternatives to BBT that have been suggested, instead of denouncing these theories simply because they are different to current understanding.
     
    Last edited: Oct 22, 2007
  16. Oct 22, 2007 #15
    I am all for remaining skeptical of objects that we have not observed but only theorize exist (epicycles come to mind), but in point of fact there is observational evidence for dark matter: the flatness of galactic rotation curves, Chandra observations of the Bullet Cluster, and "streamer" dynamics in the galactic halo, amongst others. Even if we don't know exactly what it is, there's *something* out there throwing its gravitational weight around (my personal favorite is matter in the higher dimensional bulk interacting gravitationally with our brane; though that presupposes a whole host of assumptions).

    Same with dark energy. I don't know what it is, but it's whatever is making the expansion of the universe accelerate (an observed result).

    Now, neither of those two speak directly to the Big Bang. It could be that the Universe is completely different from what Big Bang Theory predicts. However, given that they are observed phenomena, any alternate theory would also have to include these effects. Therefore, I would point out that arguing against the Big Bang because it includes dark matter and energy is somewhat facetious.
     
  17. Oct 22, 2007 #16
    I could not agree more that we should remain skeptical of unobserved objects. Instead of focussing on the as of yet unproved entities we should just focus on the actual observations that have made us think that they are there in the first place. I can see one assumption in that paragraph which does well to illustrate the point i am making. You say there "there is something out there throwing its gravitational weight around", I cant see how we know that there is actaully anything physically there causing this, or whether this is infact just how gravity works on bigger scales. I am pushing my luck by listing these (all peer reviewed) papers, but they look into alternative reasons for galaxy formation, and universe formation, not based purely on gravity originating from the BB. While they obviously do not present any sort of direct disproof of the Big Bang, they are certainly alternative views that contradict current BBT.


    http://adsabs.harvard.edu/cgi-bin/n...T&data_type=HTML&format=&high=45cce9d73311457
    http://adsabs.harvard.edu/cgi-bin/n...T&data_type=HTML&format=&high=45fffb02f208845
    http://adsabs.harvard.edu/cgi-bin/n...T&data_type=HTML&format=&high=45cce9d73311457
    http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1983Ap&SS..91...19P
    http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1995Ap&SS.227..175W
    http://adsabs.harvard.edu/cgi-bin/n...T&data_type=HTML&format=&high=45cce9d73311457
    http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1995Ap&SS.227..167S
    http://articles.adsabs.harvard.edu/..._paper=YES&type=PRINTER&filetype=.pdf

    As they contradict BBT they are not awknowledged by mainstream cosmology, but they are scientifically sound enough to easily pass the peer review process. That is the problem that i have, if there was a scientific reason to dismiss these findings then i would do the same, but it seems that the only reason ever given is that people should not beleive these theories becuase only 'cranks' do. Well thats not a scientific reason last time i checked.
     
    Last edited: Oct 22, 2007
  18. Oct 22, 2007 #17
    If a theory cannot make testable predictions accurately, then of what value is it exactly? It failed the test. I personally find it a bit dubious that you want to "modify" the percentages of metaphysical entities to 'make it fit' somehow, in a purely ad hoc, after the fact manner. It's not exactly reassuring IMO to see Lambda-CDM theory fall apart the first time we take it for a test drive. I wouldn't buy a car that broke the first time I drove it. I certainly have never seen a car run on dark energy or inflation, nor have I seen these things do anything useful on earth or in nature. Why would I think that a universe operates on that stuff?

    Well, evidently I misunderstood your statements, because you sounded quite confident that A) there was certainly a big bang (meaning no other cause of "redshift" can be considered, and no other theory of cosmology can be considered), and that B) you knew exactly when this "bang" occurred. No such thing is true. At best you have evidence of "redshift" and "missing mass". Nothing more, nothing less.
     
  19. Oct 22, 2007 #18
    Those are excellent links. I had not read some of them. Thanks! EU theory/Plasma cosmology theory is still in it's infancy, but it has the distinct advantage of being able to "test" many of it's premises in a standard and "controlled" scientific manner. The other advantage of of a plasma physics theory is that plasma events and behaviors seem to scale very well over many magnitudes of order.
     
  20. Oct 22, 2007 #19
    IMO that was actually a very fair and balanced response, even from a plasma cosmology perspective. Thanks.
     
  21. Oct 22, 2007 #20

    DaveC426913

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    Logical flaw: bad analogy. A car is not a theory. Despite being tongue-in-cheek, the remark really does miss the point.

    If you're going to discard a theory, it's because you have a better theory. (You can't not have a theory, the worst you can do is to simply have a more "rudimentary" theory (the universe was sneezed out of a cosmic nose).)

    Do you have a better theory?

    I accept that the BB theory describes our observations quite well. That is all.

    I (like any reasonble person) am open to alternate theories. But they will have to be compelling enough to give BB a run for its money.


    There's a little more than that - a century of physics, astronomy and cosmology behind it as well.

    Again, I really don't know what your point is. You really seem to be looking for a fight. The BB is simply the best explanation we have. Should something come along that explains all these phenomena better, we'll be happy to accept it. But it won't happen right away - there's a lot to overcome.


    There's many horses in the 'origin of the cosmos'* race. The race isn't over - but BB is way out front.

    When you hear knowledgeable people not questioning BB, all they're really saying is "I'll put a side bet on another horse if and when one emerges from BB's dust."

    *Sorry, lets be clear: the BB theory does not say where the initial mass and energy came from, only what happened from T=0-plus-a-bit.
     
    Last edited: Oct 22, 2007
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