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Thread: What Is The Universe?

  1. #31
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    its better than the alternative tho....

    or how else do you explain the 'fine tuning'?.....

  2. #32
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    In what context are you referring to "fine tuning"? If you answer that, I may be able to explain what "fine tuning" is.

  3. #33
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  4. #34
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    Quote Originally Posted by damian1727 View Post
    I believe there is no need to account for the fine-tuning. If it hadn't happened, we wouldn't be here to ask the question. The best we can do is to assume that it happened through sheer chance. To ask why it happened is like asking why a fair coin landed on heads rather than tails. I see no reason for supposing that the fine-tuning was more than the chance outcome of a seriers of random events.

    By the way, I appreciate your response to Dumb amateur astronomer's accusing me of arrogance.

  5. #35
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    Talking

    no problem...

    i would beg to differ on ''fine tuning'' ... as i understand it the universe or our part of it came into being as a quantum event with as we understand at present the constants masses forces getting their values ''at random''

    we are here to ask the question so it did happen and the question asked !!

    i like it as it suggests many many ''universes''



    sheer chance is not very likely when you look at the odds...

    i dont have them in front of me but its like the biggest number you ever saw!

    i'll look them up if you like

  6. #36
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    damian 1727: i would beg to differ on ''fine tuning'' ..as i understand it the universe or our part of it came into being as a quantum event with as we understand at present the constants masses forces getting their values ''at random''. we are here to ask the question so it did happen and the question asked !!

    dcl: I know of no reason for supposing that the "quantum event" occurred other than as a spontaneous event. The world is full of spontaneous events. Ancient peoples attributed such events to the actions of capricious gods, but modern people attribute them to sheer chance. I still say that if not for that event, we would not be here to argue about why it happened.

    damian 1727: i like it as it suggests many many ''universes''

    dcl: I see no reason for postulate other universes, presumably one corresponding to each of the infinity of other alternate events that could have happened but, as far as we are aware, didn't. Suppose that a mouse nibbled at the cheese in a mouse trapped and was caught. The trap could have been defective and allowed the mouse to enjoy its meal and go home to tell its family about it, but that doesn't imply that there is another entire universe in which this actually happened.

    damian 1727: sheer chance is not very likely when you look at the odds...

    dcl: The fact that it happened nullifies the odds against its happening.

    damian 1727: i dont have them in front of me but its like the biggest number you ever saw!

    dcl: I agree.

    damian 1727: i'll look them [odds against the quantum event's having happened] up if you like

    dcl: Don't bother. I agree that the number is horrendously large, but that fact implies nothing about the possible existence of that alternate universe as existing somewhere as a real universe. An alternate universe is only an idea, not something that actually exists. The very word "alternate" implies the actual occurrence of one of a number of possibilities and the nonexistence of all contrary possibilties.

  7. #37
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    dcl The fact that it happened nullifies the odds against its happening.


    me huh ? i never understood this it makes no sense

    i might win the lottery but the odds of me doing so are as they were..

    and it also makes sense that if something happened once it could happen twice....or that big number we agreed on


    we are not aware they did or did not

    as i see it if quantum fluctuations in a void can do this then im sure they do
    and as i see it fine tuning most certainly raises an eyebrow (!!) and i feel better with the very logical and beautiful explanation that is the multiverse

    also on a completely personnel level i kinda take it as a an act of faith that the world is always far more complex and amazing than i could ever possibly imagine so i would not choose to limit myself to one universe if in fact i could have many for the same price

    and it shuts (no it doesnt) the god squad up


  8. #38
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    damian1727, I agree. The chance against our Universe's having come into existence already fine-tuned for human life to arise was extremely high. It happened, the high probability against its happening notwithstanding.

  9. #39
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    If the universe by definition is 'everything', then what is the rationale for the term coined 'multiverse'. I never quite understood how that came about. Perhaps it is just semantics, but if we want to define 'universe' to mean all that is, then we should not refer to supersets of that. Granted it gets tedious to always say things like 'our observable universe' or 'all space-time that is causally connected'. I think if you allow existence of the concept of potentially disconnected spacetimes, then 'universe' as stated cannot be given the definition of 'all matter and energy' without a little refinement.
    Last edited by jseats; 2008-Jun-01 at 07:53 PM. Reason: typo

  10. #40
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    true dat

    :P

  11. #41
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    damian1727, I just discovered that I committed a monstrous goof in my statement responding to your statement about fine-tuning of the Universe. By saying "high" when I meant to say "low", I said precisely the opposite of what I intended to say: a horrific example of careless forgetting to proof to assure that I was saying what I meant to say. Sorry, people. I meant to say that I agree with you that the probability of the Universe's coming into existence fine-tuned for human life to occur was highly IMprobable.

    As for the term "multiverse", I want no part of it. I know of no evidence for there being more than the one Universe that we know, the "branes" of string theory notwithstanding.

    jseats, I agree wholeheartedly with your rejection of the concept of multiverses. I see no useful purpose in speculating about the existence of universes other than the one we know unless there is a possibility of our being able to test for their existence. On the other hand, I do feel that it is important to distinguish the universe and the observable universe because they are drastically different, and it is often important to know which one is being referred to.

  12. #42
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    The universe is a big ball of wiggley-wobbley... timey-wimey... stuff.

  13. #43
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    dcl i may be wrong but i dont think jseats was saying that there was no multiverse per say he/she was saying that if we stick with the original definition of universe to mean EVERYTHING EVER .. including different space time bubbles and dimensions then your original deffinition ... all matter and energy... was oversimplistic

    i think thats what he/she said



    the multiverse is the simplest explanation for fine tuning

  14. #44
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    Quote Originally Posted by damian1727 View Post
    dcl i may be wrong but i dont think jseats was saying that there was no multiverse per say he/she was saying that if we stick with the original definition of universe to mean EVERYTHING EVER .. including different space time bubbles and dimensions then your original deffinition ... all matter and energy... was oversimplistic

    i think thats what he/she said



    the multiverse is the simplest explanation for fine tuning
    jseats said, "If the universe by definition is 'everything', then what is the rationale for the term coined 'multiverse'. I never quite understood how that came about. Perhaps it is just semantics, but if we want to define 'universe' to mean all that is, then we should not refer to supersets of that." This seems to me to be an argument against use of the term "multiverse" as being more inclusive than the term "universe".

    He went on to say, "Granted it gets tedious to always say things like 'our observable universe' or 'all space-time that is causally connected'. I think if you allow existence of the concept of potentially disconnected spacetimes, then 'universe' as stated cannot be given the definition of 'all matter and energy' without a little refinement." This seems to me to be no more than an argument against saying "our universe" when one means "our observable universe".

  15. #45
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    he would call the multiverse .. universe.. as it means everything....

    if you allow for disconnected spacetimes..(universes to us) then .....

    nevermind

  16. #46
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    I believe that I failed to make it clear in my last remark that I am in agreement with jseats regarding ambiguity in the way the term "universe" is frequently used to refer to less than the entire Universe, the latter referring to everything, excluding nothing.

  17. #47
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    sooooooooo what i and many others term the multiverse you would would call universe?......?

    and what would the word for the individual ''bubbles' be?

    even tho you dont think they exist you would dtill need a word to tell me ~!!!!

    lol

    way to confuse ourselves!

    when i say universe i mean the whole of space time that came into being 13.7 billion years ago

    but i believe *scarey voice* there IS soOoO mucH mOreee....

  18. #48
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    Quote Originally Posted by damian1727 View Post
    sooooooooo what i and many others term the multiverse you would call universe?......?

    and what would the word for the individual ''bubbles' be?

    even tho you dont think they exist you would dtill need a word to tell me ~!!!!

    lol

    way to confuse ourselves!

    when i say universe i mean the whole of space time that came into being 13.7 billion years ago

    but i believe *scarey voice* there IS soOoO mucH mOreee....
    As far as I know, there is no evidence for more than the single universe that we live in. Any speculation to the contrary is only that and is backed by no evidence whatever. I feel that such speculation remains sterile until at least some evidence has been found for it. Until individual bubble universes are found, I wouldn't worry about what to call them. If someone wants to believe in bubble universes, I'll be content to let him devise a name for them. When I say "universe", I, too, mean the whole spacetime that appears to have come into existence 13.71 billion years ago. I, too, suspect that there is much more to the Universe than we know about or can even guess at at present.
    Last edited by dcl; 2008-Jun-08 at 04:26 PM.

  19. #49
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    A lot of science or cosmology is based on the concept that "If it can happen here, it can happen somewhere else". Why not apply this to the universe itself?

    The simple reason for the multiple universe idea is that it removes the fine tuning problem.

    If this seems too speculative, consider that the fine tuning problem itself is really a philosophical question - you are asking why all the physical constants are at those particular values rather than other values - you are asking what mechanism defined those values - you are asking about the mechanism responsible for our universe being the way it is...

    We now have a few contenders in cosmology that might take the time-line back further than the beginning of "our" universe, things like M-theory and Loop Quantum Gravity, but we have no way so far to test these ideas and they only take the "mechanism behind" question back along the time-line with them anyway.

  20. #50
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    Quote Originally Posted by speedfreek View Post
    A lot of science or cosmology is based on the concept that "If it can happen here, it can happen somewhere else". Why not apply this to the universe itself?

    The simple reason for the multiple universe idea is that it removes the fine tuning problem.

    If this seems too speculative, consider that the fine tuning problem itself is really a philosophical question - you are asking why all the physical constants are at those particular values rather than other values - you are asking what mechanism defined those values - you are asking about the mechanism responsible for our universe being the way it is...

    We now have a few contenders in cosmology that might take the time-line back further than the beginning of "our" universe, things like M-theory and Loop Quantum Gravity, but we have no way so far to test these ideas and they only take the "mechanism behind" question back along the time-line with them anyway.
    "here" and "somewhere else" in the expression "If it can happen here, it can happen somewhere else" do not usually refer to locations in different universes. There is no basis for supposing that multiple universes would remove the fine-tuning problem. I am not asking why all of the physical constants have the values that they do. I think these values have the values that they do merely because we wouldn't be here to ask the question if they different, We shouldn't ask for causes when there were none. I'm not aware that M-theory and quantum gravity offer to take the time line back before the Big Bang.

  21. #51
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    Well, M-Theory proposes the possible existence of multi-dimensional membranes which interacted, causing our universe.

    As for Loop Quantum Gravity, Abhay Ashtekar and Martin Bojowald have released papers stating that according to loop quantum gravity, the singularity of the Big Bang is avoided. What they found was a prior collapsing universe. Since gravity becomes repulsive near Planck density according to their simulations, this resulted in a "Big Bounce" and the birth of our current universe. These topics are an active research in loop quantum cosmology.

    By the way, I wasn't implying that you were asking about the fine-tuning problem, that was bad wording on my part. I was just referring to the fine tuning problem in of itself. I agree with you regarding the lack of a need for a cause.

  22. #52
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    Exclamation

    dcl ..... I am not asking why all of the physical constants have the values that they do. I think these values have the values that they do merely because we wouldn't be here to ask the question if they different,

    me .... that is not a very satisfying argument ... how does it feel as a physicist having to put all the force ratios ..constants ..partical masses into your equations by hand ... they should arise from the theory and in an ideal world not be able to take any other values

    then we could say ''see there you go thats explained ''

    just to say well im here so that explains it is just utter nonsense imho

    we need to understand how the universe came to be the way it is...thats physics...so the search continues and we have yet to explain how the
    force ratios ..constants ..partical masses came to hold the values they do..

    im sure that the future will make great in roads in our understanding

    but it wont be im here so thats no suprise !!!! it is a suprise.!!!
    :


    the anthropic principle says i find myself in a universe i can be in

    it DOES NOT say that the values are such SO I CAN BE HERE..... think these values have the values that they do merely because ....it is no reason

    bugbear of mine

  23. #53
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    Perhaps there are/have been billions of universes (but where did they come from?). Perhaps the laws of physics are different in each and where a universe works properly life will arise to ask these questions. Perhaps the current universe is part of a single sequence of universes that gradually settle towards the ideal laws of physics (but where did it come from?). Perhaps the universe was designed by an intelligence (but who designed them?). Perhaps multi-dimensional membranes clash together and form universes (but where did the 'branes come from?).

    The "what is the mechanism behind it?" question just gets moved backwards.

  24. #54
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    works properly ???ideal laws of physics???

    lets just keep open minds and rely on science to let us know what we know and be big enough to know what we dont

    you sound as if you think further investigation is not worth it

    folk always put something called god into gaps in knowlege....so what?

    lets push the gaps back

    ultimatley you seem to be asking the ancient question WHY SOMETHING AND NOT NOTHING?

    for now i live with the fact that NOTHING is unstable and liable to fracture into something the fact that this question is along way away from being know should not stop us thinking


  25. #55
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    Quote Originally Posted by dcl View Post
    damian1727: if energy/matter can neither be created or destroyed in our universe, then how come it is here at all?

    dcl: Science has no answer for that question.
    Here, your answer is correct. I think accomplished physicists may ask themselves the same question - "Why is there anything at all?" or "Why isn't there nothing?" but only when they're in philosophical moods, I suppose.

    Quote Originally Posted by dcl View Post
    ...ran the movie backward as far as knowledge would allow and sensibly stopped there to avoid uninformed speculation. That took it back to 10-43 sec....
    Here your answer is incorrect. We can't get anywhere near 10-43 sec. From my recent reading on the subject, many major names in the field all seem to agree on how the movie would rewind back to 1 second. If I'm not mixing my units, I believe our most powerful accelerators can simulate conditions somewhere around 10-15 sec. Beyond that, we have no observational data, and various physicists have different ideas.
    Everyone is entitled to his own opinion, but not his own facts.

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    Quote Originally Posted by Cougar View Post
    Beyond that, we have no observational data, and various physicists have different ideas.
    They are different ideas, but they all seem to be dealing with the apparent failure of string theory to derive a single, unique solution that explains our universe. As Lee Smolin points out in The Trouble With Physics [2006], after about 30 years of effort developing string theory and its offshoots, the theory turns out to be just TOO successful. (Well, he doesn't put it that way, but I think it's applicable.) Some have estimated the number of string theory solutions at 10500. Note the number of particles in our universe is 'only' around 1080.

    Leonard Susskind, the "father" of string theory points out in his 2006 book, The Cosmic Landscape, that this suggests there are 10500 possible universes allowed by the theory, and there's no reason to think that many of the longer-lived ones aren't actually existing, similarly to how ours happens to be.

    I kind of like the picture painted by Alex Vilenkin in his remarkably well-written entry, Many Worlds in One [2006]. If I haven't mixed up my authors, Vilenkin does a masterful job in his explanation of eternal inflation, where the "whole universe" is in constant, exponential expansion, and what we call the big bang is just one bubble universe that "gracefully exits" the background frenetic inflation and proceeds to evolve according to the physical laws and constants that were set in the first seconds of the so-called "bang." And there's untold number of such bubble universes, which will unfortunately never be able to interact in any fashion with any other due to the superluminal expansion going off between them.

    Though Vilenkin's description seems plausible, Smolin is quite right in his criticism of the craft that seems to more commonly be positing schemes that have no fair chance of finding any observational support. The space between theory and experiment seems to be undergoing.... exponential inflation.

    To Vilenkin's credit, he does predict some fundamental of his idea may be distinguishable from other theories by a close analysis of the gravitational wave background. Of course, we are currently having a hard time detecting the gravitational wave foreground, so....
    Last edited by Cougar; 2008-Jun-10 at 03:15 AM. Reason: typo...
    Everyone is entitled to his own opinion, but not his own facts.

  27. #57
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    i would just like to say i never said this...

    damian1727: if energy/matter can neither be created or destroyed in our universe, then how come it is here at all?


    it got confused in all the cut and paste and was said by RAVENS CRY

    it got in my post so i could answer it... (tho i cant lol )

    glad thats clear

  28. #58
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    Quote Originally Posted by damian1727 View Post
    works properly ???ideal laws of physics???

    lets just keep open minds and rely on science to let us know what we know and be big enough to know what we dont

    you sound as if you think further investigation is not worth it

    folk always put something called god into gaps in knowlege....so what?

    lets push the gaps back

    ultimatley you seem to be asking the ancient question WHY SOMETHING AND NOT NOTHING?

    for now i live with the fact that NOTHING is unstable and liable to fracture into something the fact that this question is along way away from being know should not stop us thinking

    Damian, it was you who introduced the fine-tuning problem into this thread, and once this has been introduced, it sends the discussion tumbling inevitably towards the "why something and not nothing" question.

    I was just suggesting a number of alternative possible solutions to the fine-tuning problem, but all they do is push the question further away - the question is still there, lurking!

    Now, dcl is happy to leave the question unanswered, and I tend to agree with him, but I see no problem in investigating further if you want, which is why I mentioned things like M-Theory and Loop Quantum Gravity. M-Theory allows multiple universes ('branes bang together and cause universes), and Loop Quantum Gravity allows a sort of cyclical universe (no big-bang, but a previous contracting universe).

  29. #59
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    Quote Originally Posted by damian1727 View Post
    ...i never said this...
    Oh, sorry, Damian and Raven. It's certainly a question that I've seen toward the beginning of numerous books and articles. "Why is there something instead of nothing?" The various multiverse and bubble universes ideas do provide an answer to this question: There are zillions of different bubbles, all with different qualities, and ours happens to allow for life to evolve, obviously. End of answer. Unfortunately, such an answer has no observational support, is not falsifiable, and therefore has kind of left science behind. But apparently scientists are tired of sweeping the fine-tuning question under the rug....
    Everyone is entitled to his own opinion, but not his own facts.

  30. #60
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    In this contribution, I'll respond on some of the things said by others regarding my contributions since my last contribution. Each entry will start with the pseudonym of the person on whose entry I'm commenting immediately followed in a new paragraph starting with my own pseudonym followed by my comment.

    speedfreek: M-Theory proposes the possible existence of multi-dimensional membranes which interacted, causing our universe.

    dcl: Let's not lose sight of the fact that, as attractive as M-theory may be in some respects, there is absolutely no evidence for or against it. So let's remember that at best it is only a hypothesis awaiting the first evidence that it may be valid. I'm under the impression that the same must be said for loop quantum gravity.

    speedfreek: As for Loop Quantum Gravity, Abhay Ashtekar and Martin Bojowald have released papers stating that according to loop quantum gravity, the singularity of the Big Bang is avoided. What they found was a prior collapsing universe.

    dcl: I, too, think it plausible that the present expansion was preceded by a bounce from a previous contraction, but I'm not aware that there is any evidence for a bounce, so we should not seize on the idea that there was one.

    damian1727: "I am not asking why all of the physical constants have the values that they do. I think these values have the values that they do merely because we wouldn't be here to ask the question if they were different" is not a very satisfying argument ... how does it feel as a physicist having to put all the force ratios ..constants ..partical masses into your equations by hand ... they should arise from the theory and in an ideal world not be able to take any other values

    dcl: Physicists agree that values for physical constants should ideally arise from the theory, but most theories aren't as complete as we'd like them to be in that respect.

    damian1727: just to say well im here so that explains it is just utter nonsense imho

    dcl: I don't know where you got that quote. My being here explains nothing.

    damian1727: we need to understand how the universe came to be the way it is...thats physics...so the search continues and we have yet to explain how the force ratios ..constants ..partical masses came to hold the values they do.

    dcl: We'd like to understand how the universe came to be the way it is, but we don't need to.

    damian1727: you sound as if you think further investigation is not worth it

    dcl: It's not clear that that remark was addressed to me, but it appears to me that it was. I feel that further investigation in some areas is pointless. For example, the idea that the Universe has the shape of a cube, a 3-torus, a doughnut, or a dodecahedron is pointless because the suggestion that the Universe has any of those shapes seems preposterous to me. The shape that seems plausible to me is that of an expanding four-dimensional hypersphere.

    damian1727: ultimatley you seem to be asking the ancient question WHY SOMETHING AND NOT NOTHING?

    dcl: I am not asking that question and am curious as to why you think I am.

    Cougar: Here [in runningn the movie backward] your answer is incorrect. We can't get anywhere near 10-43 sec. From my recent reading on the subject, many major names in the field all seem to agree on how the movie would rewind back to 1 second.

    dcl: I suggest you broaden your reading. There are any number of respected sources that give that 10-43 figure. That figure comes from the Standard Model of particle physics, not from accelerator experiments.

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