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How we know the universe has a beginning

  1. Jan 21, 2014 #1
    Please be patient with me, and forgive me for my ignorance, but I do think according to logic and take into account the facts established by science.

    Here is my take on how we come to know that the universe has a beginning.

    The universe is expanding, so scientists by mathematics infer backward to the very point beyond which point they would fall off into nothingness: so, they stop their mathematics at that point which is still into something instead of literally nothing.

    Now, this point is a very dense hot point of energy: it is something, it is not nothing.

    From this point onward we say that it is the beginning of the universe, and it has expanded from that beginning toward the present state which is the expanded universe as we can observe it now, and it is still expanding.


    Is that idea okay as coming from a thinking person, thinking according to logic and based upon the facts established by science?



    Yrreg
     
  2. jcsd
  3. Jan 21, 2014 #2

    Chronos

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    A theory of quantum gravity is probably needed to attempt to answer such a question.
     
  4. Jan 21, 2014 #3

    phinds

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    If I understand you correctly, you are saying (and this is the "big bang theory") that we understand the universe up to a point in the past (and this point, by the way, is called one Plank time) and then backwards beyond that point, the model fails and we don't really know WHAT is happening, but we SAY it is the beginning of the universe because that is what the model says, even though as Chronos points out we really don't really know what is happening further back than one Plank time.

    If that is what you are saying, then yes, that is correct.
     
  5. Jan 21, 2014 #4

    jcsd

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    There's good reasons within the limits of big bang theory to say that the Universe had a beginning. The reason is , if you make certain assumptions (that most people would find to be reasonable, e.g. no negative energy density), when you trace the history of any object in the Universe back in time you find that there is a limit as to how far you can trace it. Its history abruptly begins some finite time ago.

    Where the history of all the objects start is called the big bang singularity, though it is probably best not to interpret the singularity itself as a physical object.
     
  6. Jan 22, 2014 #5
    There is a paradox with one apparent explaination that implies a beginning. Consider that at every point-line-of-sight you examine in the sky has a star somewhere within it's path (and always has had one at some time in the universe's past). Why then is the sky not completely illuminated? One explaination that does not create unecessary complexity is; the light from those stars has not yet reached us. If the universe has an infinite past, then the light shall have reached us, ergo a beginning is required.

    Ref Olbers' paradox
    Paradox: The Nine Greatest Enigmas in Physics
    by Jim Al-Khalili
     
  7. Jan 22, 2014 #6
    I read this the other day but left me very confused, your wording helped me a lot, thanks!
     
  8. Jan 22, 2014 #7

    phinds

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    No, that is not correct. It is only necessary that the currently expanding universe have a visual horizon of some sort (which it does ... the CMB). It may well be part of a cyclic universe that visually only goes back 14 billion years within our cycle. I don't believe this is the case but so far it is not definitely false, so your conclusion that there must be a beginning is false.
     
  9. Jan 22, 2014 #8
    Another problem with Olberts paradox other than the one phinds pointed out is that it only applies to a universe that is infinite in size.
     
  10. Jan 26, 2014 #9
    The concepts of paradox and of infinite are invalid concepts.



    You bring in the term and concept of paradox and of infinite.

    Forgive me, but the concept of paradox and the concept of infinite are just concepts, they do not have any corresponding entities in objective reality to which they are or can be referred to.

    Consider the facts which today here and now surround us, by thinking according to logic all the way back, we come to know that there is a beginning in time and in space when and where the universe does have a beginning.

    I like you to tell us what is your idea of a paradox, does it have any situation in actual objective reality upon which it is founded, or it is all an idea in your mind which is purely and exclusively in your mind’s operation and it has nothing in facts to support it.

    Also give us your idea of what is an infinite? I see it to be a pure concept in our mind which has no corresponding entity in actual objective reality.

    Here is my point in this thread, namely: when we think according to logic and we ground ourselves upon the facts of actual objective reality, the universe does have a beginning in time and in space, it is at that point when time and space themselves have a beginning.

    Perhaps you want to tell us that according to your idea of a paradox and an infinite, the universe does not have a beginning in time and in space, or what?

    Now, you will ask me, what then is the situation at the point when and where the universe has its beginning when and where time and space themselves began to exist?

    Thinking according to logic and grounding myself on facts as we know facts today and here now in the universe that we are existing in, and living in, and operating in, my answer is that it is the situation where and when from the part of the universe it has its limit at which limit it is in contact with the realm of existence that is not subject to time and space.

    That is from thinking according to logic and grounding myself on the facts of actual objective reality as we have access to them (facts).

    Forgive me, perhaps you should tell us what is your idea of a paradox and what is your idea of an infinite; the way I see them, they are just pure concepts but without any corresponding entities in actual objective reality in the universe, nor in the totality of existence that is broader than the universe we are existing in and living in and operating in.

    You see, our mind is wonderful in entertaining ideas which are just pure concepts and these pure concepts can be not only pure concepts but even what I call invalid concepts, but for the wonderful versatility of our mind being able to entertain them even though they are impossible to exist in the real actual objective reality of existence, neither in the universe nor in the totality of existence which is broader than the universe.


    Anyway, tell me, what is your point in bringing in the idea of a paradox and the idea of an infinite, is it to tell us that the universe does not have a beginning?

    In which case, then tell me what is your concept of a beginning.


    Yrreg
     
  11. Jan 26, 2014 #10

    phinds

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    Your conclusion that time and space definitely have a beginning is not science, it is a personal philosophy of yours, not supported by empirical evidence. The universe does not care about your logic, it just does what it does and so far, we don't know WHAT it does back beyond one Plank time.
     
  12. Jan 26, 2014 #11
    'Paradox and infinite' are analogous to 'I think there for I am'. If you have nothing, there's gotta be everything... somewhere else.

    Just thinking out loud, how much does Descartes, 'cogito ergo sum' play into the world of modern pysics?
     
  13. Jan 27, 2014 #12

    Chronos

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    So what, what does intuition have to do with science? We already know the laws of nature do not respect human intuition - e.g., quantum theory.
     
  14. Jan 29, 2014 #13

    Well, perhaps you care to tell readers here what is supported by empirical evidence, like the multiverse, even without logic to infer into its hypothetical existence?

    So, if there is empirical evidence then you can dispense with logic?


    Here is my op again:


    Please focus on my words, in particular the line in bold:


    Empirical evidence does not stand on itself, it must be submitted to logical thiinking which is critical thinking.




    Yrreg
     
  15. Jan 29, 2014 #14

    Well, Descartes is obviously tell us all humans that we have the foundation of all thinking and doing, namely, that we know we exist from the consciousness in each of us being aware that we do exist and live and operate.

    Now, when we agree on that fact by communal co-affirmation among conscious selves, then we are grounded on the reality that we do exist, etc.

    What do you want to point out, that we cannot be sure that we exist because we might be all into a delusion or illusion or hallucination?

    Okay, the folks here who are serious about their being just into a delusion or illusion or hallucination, you folks can take a leave of absence from this forum.

    We folks who subscribe to the consciousness of ourselves thinking thereby being consciously operating, we will continue exchanging our thinking and opinions as we exist and live and conduct ourselves consciously, by which consciousness we are all aware of the reality of our existence and operation.



    Yrreg
     
  16. Jan 29, 2014 #15

    I don't recall using the term intuition.

    Tell me, but forgive me for being inquisitive, do you have an idea of what is intuition?

    You appear to use the word intuition as though it is opposed to observation and logical thinking.


    What I am saying all the time is that by logic and grounding ourselves on the facts established by science we know that the universe has a beginning.


    Now, it is a taboo among some scientists, sad to say, my impression is that a big number of them, to no longer think any further according to logic, for fear (and that is the taboo) of no longer being grounded on the facts of science and mathematical thinking, which mathematical thinking is also founded on logic, the logic, namely, that once you set up your axioms to cover your mathematical operations, then you must be logical, meaning coherent and consistent all throughout your mathematical operations as to not commit any incoherency and inconsistency into an infringement of the axioms you have set up as your laws of operation, and these axioms must themselves adhere to their intrinsic among themselves coherency and consistency -- otherwise there is no logic but all irrationality or fudge factoring.


    Now, the taboo is the fear of going into a realm of existence that is transcendental; but if that is where logic leads, why the taboo? It is then all superstitious fear, or what? Fear of peers' pressure who peers are already into a taboo?




    Yrreg
     
  17. Jan 29, 2014 #16

    phinds

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    I have no idea what you are talking about. There is zero evidence of a multiverse.

    What does that have to do with using logic to come to a conclusion, as you did, that is not supported by any fact?
     
  18. Jan 29, 2014 #17

    Chronos

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    I intended intuition in the sense of logic and reasoning.
     
  19. Jan 29, 2014 #18

    phinds

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    And my continuing response is that this is unsupportable personal speculation on your part. It may well be that the universe has a beginning (kind of hard to imagine how it could not) but that is NOT established by science, it is purely a personal conclusion of yours.

    It is certainly true that the math of the "big bang theory" can only be carried backwards to what is called the "singularity" but "singularity" just means we don't know WHAT was going on at that point, not that it is definitively the beginning of the universe, just that it IS the beginning in terms of this particular math model.
     
  20. Jan 29, 2014 #19

    ZapperZ

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    Closed, pending moderation.

    Zz.
     
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