Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The start of the universe

  1. Sep 11, 2009 #1
    Does it make sense to say the universe was "created" at the big bang? If time only exists within the universe, doesn't it make more sense that the whole thing was created at once? Anselm made this point a very long time ago. Any opinions?
     
  2. jcsd
  3. Sep 11, 2009 #2

    mathman

    User Avatar
    Science Advisor
    Gold Member

    There are a lot of guesses as to what the universe may have been like before the big bang. There is also a related question about what may exist outside the known unverse.
     
  4. Sep 11, 2009 #3

    apeiron

    User Avatar
    Gold Member

    Another way of looking at it is the phase transition approach - with time being part of what crystallises out.

    So "before" the big bang, there was a more chaotic stage like a vapour phase. Time, along with space, was "gaseous" - there, but in a less coherent sense of some kind.

    Then the big bang is like the transition from gas to liquid, or even liquid to ice. From the instant when the transition happened, a liquid form of time and space exists - same stuff, more organised in some way.

    So time "always existed" and then went through sharp transitions which made it more definite or orderly.
     
  5. Sep 11, 2009 #4

    marcus

    User Avatar
    Science Advisor
    Gold Member
    Dearly Missed

    Hi Apeiron! Your mascot Anaximander might well be proud of us I think.

    I mean proud of this generation of physicists (not necessarily us right here at PF although we do our bit too.)

    Many current models of how expansion started are handled in chapters by the various experts in the collection Vaas edited. Maybe "madness" and mathman would be interested too. The table of contents has been changed:
    http://www.springer.com/astronomy/general+relativity/book/978-3-540-71422-4?detailsPage=toc [Broken]

    We are not talking about anything so grand as "The start of the universe" :biggrin:
    We are only talking about modern ideas about conditions before the start of expansion (popularly called 'big bang') and what may have led up to it. I will copy out the new TOC and highlight some phrases.

    ==quote==
    - Introduction: Beyond the Big Bang.

    - Cosmic Inflation: How the Universe Became Large and Plentiful.

    - Eternal Inflation: Past and Future.

    - The Big Bang Singularity: Conditions and Avoidance.

    - Big Bounce: Beyond the Threshold of Classical Cosmology.

    - The Emergent Universe: Arising from a Static State Without a Singularity.

    - Quantum Cosmology: Whence and Whither.

    - Quantum Origins: Gravitational Instability of the Vacuum and the Cosmological Problem.

    - Island Cosmology: The Universe from a Quantum Fluctuation.

    - Cosmology from the Top Down: Anthropic Reasoning and Prediction in a Quantum Universe.

    - Loop Quantum Gravity and Cosmology: Avoiding the Big Bang Singularity from First Principles.

    - Loop Quantum Cosmology: Effective Theories and Oscillating Universes.

    - The Holographic Universe: Space and Time in String Theory.

    - The Pre-Big Bang Scenario: String Theory and a Longer History of Time.

    - String Gas and String Inflation: Cosmology with Extra Dimensions.

    - The String Landscape: Exploring the Multiverse.- Selection of Initial Conditions: The Origin of Our Universe from the Multiverse.

    - Cosmic Natural Selection: Status and Implications.

    - The Cyclic Universe: Ekpyrosis, Dark Energy and Large-Scale Structure.

    - The Arrow of Time: The problem of Cosmic Initial Conditions.

    - Self-Creating Universe: A Time Loop at the Beginning.

    - (Quasi)-Steady-State Scenarios: An Alternative to Big Bang Cosmology?.

    - The Mathematical Universe: Eternal Laws and the Illusion of Time.

    - Eternal Existence: The Furthest Future.

    - Index.
    ==endquote==
     
    Last edited by a moderator: May 4, 2017
  6. Sep 11, 2009 #5

    apeiron

    User Avatar
    Gold Member

    Singularities and bounces would represent a different ontic view of course. This would not be natural to a phase transition approach as I've argued before. Shame there are no authors attached to chapters yet as that would help identify who is lining up "on my side" here.

    But I will note that Vaas as the editor is someone whose thinking I like. And Davies gives the book a big plug.

    Anyway, here is a snippet of Vaas that would be sympathetic to my view.

     
  7. Sep 12, 2009 #6
    The Stoics, amazing chaps!
     
  8. Sep 13, 2009 #7
    Thanks for the replies. I actually posted this thread in the philosophy forum but it was moved here, which has given a different type of reply than I imagined. Suppose that we live in a "block universe", ie the universe is a 4d block including time. Then from this point of view, the universe isn't necessarily created at the beginning - the whole thing is really created at once.
    The idea of time going through phase transitions doesn't make sense to me. I can only imagine this process unfolding over time, but here time is the thing which is changing. By the way I do have a mathematical physics background, I'm just posting some non-technical questions.
     
  9. Sep 13, 2009 #8

    marcus

    User Avatar
    Science Advisor
    Gold Member
    Dearly Missed

    and could be eternal.

    That is, not "created" at all, simply existent.
     
  10. Sep 13, 2009 #9

    apeiron

    User Avatar
    Gold Member

    Why is it so hard to imagine time having a development? You think of time as being a highly ordered thing, don't you? It is very strict in the way it has a directionality, a universal presence, clear causal structure.

    So now you just think of a disorderly version of temporality. Time as we know it having broken down into a pregeometry, as Wheeler nicely put it. Fragmentary or fleeting scaps of temporal coherence.

    Some global parameter is usually changing steadily in phase transition models. Usually some kind of thermodynamic notion of temperature. When things are hot, local kinetics overwhelm greater structure. But when things cool to the critical point, latent local properties (like charge) can suddenly overcome that disordering kinetics and all the system's locales will line up in some orderly global fashion (like the magnetisation of an iron bar).

    So all we have to imagine is a hot realm of spacetime pregeometry that cools sufficiently at some point for crisply structured 4D dimensionality to condense out. As Linde suggested for instance with his chaotic inflation story.

    This was of course a phase transition of an infinite inflaton field, an energy state that existed "in" space and time. So different in that regard. But many people seem quite happy with a foamy notion of spacetime itself, so why not a phase transition model for pregeometry?

    Now the block time view is the one that really makes no sense to me. When development is all around us, why does this Parmidean vision hold any appeal?

    Equations model the world in terms of micro-symmetry, and it is easy to understand why this reductive approach is maximally efficient. But to then believe that the macro-asymmetry of the world is just some strange perceptual illusion?
     
  11. Sep 13, 2009 #10
    Marcus - I see the question of whether the universe is eternal as entirely independent of whether it had a creation. Any "creator" would necessarily be outside of time. If you don't accept the creation as the beginning, then the infinite regress shouldn't matter.

    Apeiron - the reason I can't "imagine is a hot realm of spacetime pregeometry that cools sufficiently at some point for crisply structured 4D dimensionality to condense out", is that I can only imagine something cooling over a period of time, and without time I can't imagine any cooling process.
     
  12. Sep 13, 2009 #11

    marcus

    User Avatar
    Science Advisor
    Gold Member
    Dearly Missed

    In that case I can't see that the "creation of the universe" is very interesting. I'd be much more interested in learning about whatever physical process could have led up to the start of expansion.

    And how did it get started with the temperature and expansion rate and types of matter that it did. And the kind of geometry it has.

    I'd like it if those things could be traced back to conditions and process some period of time before expansion started. As some models make a stab at doing nowadays (like in that book I mentioned). Collapse and bounce models have gotten a lot of researchers interested and quite a bit of work is being done on them.

    Studying, for example, a quantum cosmology bounce model doesn't have anything to do with a "creator" "creating" a possibly eternal existence "outside of time". That kind of talk is just another way of saying existence exists.

    Not very interested talking about that. More interesting to try to understand how this what we see got started, and from what, and why it's this way (to the extent we can explain that) instead of some other.
     
  13. Sep 13, 2009 #12
    True, it may not be interesting from a scientific point of view, but then I posted this thread in the philosophy forum. It is certainly interesting (to some people) from a philosophical and theological point of view (I am not a theist either). I find it an interesting idea that the universe wasn't "created" at the beginning. You've probably heard the analagy between before the big bang and north of the north pole, and you wouldn't claim that the earth was created at the north pole. Still though, it's more for me to arrange things in my head than an important scientific point.
     
  14. Sep 13, 2009 #13

    apeiron

    User Avatar
    Gold Member

    Madness - You are talking about Hartle/Hawking imaginary time story here. And it has its similarities with the phase transition from pregeometry I'm talking about. Spacetime asymmetry gets dissolved back into symmetry.

    Of course, the north pole analogy is a tad misleading. The north pole is actually singled out (roughly I know) by the physical property of the earth's axis of rotation. So you could tell that you were crossing this locus of rotation. And you could say that rotation was "created" from that locale in some symmetry-breaking sense.

    So at the north pole, you would experience pure rotation and no translation. A step away and the extra kind of motion would begin.

    Now if you want to imagine "going beyond the north pole", you would be going from a situation where you physically can know that you are rotating on the spot - because you can see you are on top of a world - to one where you are spinning in "nothing". And now you can no longer tell whether you spin (or indeed translate). Your status - to use the jargon - is vague. Indefinite, indeterminate - deeply symmetrical.

    Anyway, if you want to arrange things in your head - it is excellent to be aware of the full range of alternative conceptions of cosmological "starts", then I did post on this in a thread on vagueness.

    I run through the four familiar options discussed by Paul Davies, the best overview provider about IMHO, and then start the argument for a fifth option that is derived from self-organised phase transistion style modelling.

    https://www.physicsforums.com/showthread.php?t=301514

     
  15. Sep 13, 2009 #14

    marcus

    User Avatar
    Science Advisor
    Gold Member
    Dearly Missed


    That "north pole" analogy died only recently like in 2005. Roger Penrose gave a talk at Cambridge in 2005 where he said that until recently (like spring 2005) he himself would have used that very analogy! Before the big bang was as meaningless as "north of the north pole" and he had even heard it on BBC television.

    But it's probably not a good way to think of things, because there are now several competing ideas of straightforward causal models where something proceeds according to some causal progression (maybe even a normal idea of time) and leads to a big bang. Penrose has his own model, if you want to watch and listen let me know and I'll get the link. His mechanism is atypical, not what most people in the field study. But he draws nice pictures---he likes to cartoon with different color felt-tip pens.

    Anyway, I'd toss the "north pole" analogy.

    You probably do not want to scan thru current scientific papers, because too technical. But if by some strange chance you do:
    http://www.slac.stanford.edu/spires/find/hep/www?rawcmd=FIND+DK+QUANTUM+COSMOLOGY+AND+DATE+%3E+2006&FORMAT=www&SEQUENCE=citecount%28d%29 [Broken]

    Most papers on the list have an "abstract" or brief summary. You get this if you click on "abstract" and you get the full text if you click on "pdf".

    The beginning of expansion is not simply a philosophy topic any more. Philosophy and science have to work together on that one.

    For an interesting historical comparison, here is the same keyword search for the period 1990-2000. You will get the OLD quantum cosmology names:
    Hawking, Vilenkin, Hartle, Linde,...
    http://www.slac.stanford.edu/spires/find/hep/www?rawcmd=FIND+DK+QUANTUM+COSMOLOGY+AND+DATE+%3E1990+and+date+%3C+2000&FORMAT=www&SEQUENCE=citecount%28d%29 [Broken]

    The other search is for Date > 2006. So more recent research about big bang and black hole stuff. There was a generational change.
     
    Last edited by a moderator: May 4, 2017
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: The start of the universe
  1. Start of Universe (Replies: 1)

Loading...