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

The universe caused itself?

  1. Jan 23, 2010 #1
    I was wondering from a physics point of view if it is plausible for the universe to have caused itself to be...
     
  2. jcsd
  3. Jan 23, 2010 #2
    In my opinion, this is purely the realm of philosophy. I would love to hear opinions otherwise...
     
  4. Jan 23, 2010 #3

    Chronos

    User Avatar
    Science Advisor
    Gold Member

    Sean Carroll once wrote a paper to that effect. Apparently he since withdrew it. I believe Max Tegmark has also speculated on it as well. The theory goes that the universe arose from a quantum fluctuation in whatever state existed a prior to that. It is as good as any a priori theory of how the universe arose. It appears likely the universe did not always exist, so it is fair game for speculation.
     
  5. Jan 23, 2010 #4

    DevilsAvocado

    User Avatar
    Gold Member

    Catch-22
    I can’t tell about the physics, but logical it must be – No.

    If something is able to 'create' something, it must be present first, right? Either the universe 'existed' before it 'existed' (Catch-22)...!? Or, it did not create its own 'existence'.

    Nevertheless, the evidence is overwhelming for a 'massive event' 13.8 billon years ago, that expanded into what we see today.

    So what happened? Well, before we get GR = QM it seems hard to explain mathematically. Other possibilities might be; a Big Crunch, or colliding Branes, or a Multiverse where the 'bubbles' sometimes collide (or grow into each other’s 'territory'), or something completely new that no one haven’t thought of yet.

    I have absolutely no idea...

    But the real exciting question is: Will we live until the 'mystery' is solved?

    My guess is – Yes!

    Note1: I know – 'existence' is awkward word for the universe.
    Note2: I don’t believe in god or any other 'intelligent designer'.
     
  6. Jan 23, 2010 #5
    The universe is either opened or closed. An open universe means that there has only been one Big Bang and the universe will keep expanding until it eventually dies hundreds of trillions of years from now.

    A closed universe is when the universe keeps expanding but will eventually get back to its starting position. For example, assume that a person leaves Boston travelling to the east in a straight line. The person will travel around the world and eventually will get back to his starting position, Boston. For the universe to do this, assume that the universe keeps expanding just like the person kept on travelling. Eventually, the universe could reach its starting position, thus causing the death of the current universe but the creation of the next one instantly through another Big Bang.

    You must keep in mind, though, that these are only theories. There is no way to prove either of them true or false with today's technology. As Phyisab**** said, "this is purely the realm of philosophy." And this concept will continue to be "a relm of philosophy" until someone proves that the universe is either opened or closed.

    Therefore, the answer to your question, in one word would be "yes"
     
  7. Jan 23, 2010 #6
    No.
    If there is enough Dark Energy, Universe can be closed, but expanding forever.
    What you are explaining was correct before the discovery of DE

    So DE adds 2 more options:
    1. Closed but expanding forever
    2. Big Rip option
     
  8. Jan 23, 2010 #7
    I've heard of dark energy but I don't really understand it. Could you explain dark energy and how it contributes to the universe?
     
  9. Jan 23, 2010 #8

    marcus

    User Avatar
    Science Advisor
    Gold Member
    Dearly Missed

    No. Dmitry explained why you are wrong. The possibility of a universe that is spatially closed but which expands forever has always been a part of the theory ever since Einstein wrote down the basic equation (around 1917?) with a cosmological constant Lambda.

    Simplified popular accounts (and beginning textbooks!) tended to ignore this possibility and assume that Lambda was zero---many continued doing this until around 1998 when evidence of accelerated expansion was discovered.

    Accelerated expansion means that the simplified equations with zero Lambda must be wrong. We have to allow for a spatially closed universe (e.g. a hypersphere, analogous to the surface of a balloon but 3D instead of 2D) which expands indefinitely.

    Dark energy has been discussed a lot at this forum. You might search for it and find some earlier threads. If Dmitry wants to give you an introduction, however, that would be great.
    His explanation is apt to be both more concise and clearer than what I could provide at the moment.
     
  10. Jan 23, 2010 #9

    marcus

    User Avatar
    Science Advisor
    Gold Member
    Dearly Missed

    An additional question: if you imagine that it did cause itself, is when did it do so?

    Plausibility tends to be in the eye of the beholder. There are on the order of 10 schools of thought about what preceded the big bang (the start of expansion). On the order of 100 scientists currently researching and writing papers exploring the various models of how expansion could have started---studying various "before-the-big-bang" pictures.

    There is a book supposed to be coming out, collecting and comparing all these various ideas.
    Different leading experts contributing chapters. I have seen the table of contents and read some of the chapters, but I haven't seen the whole book. It is not out yet (in fact there have been several delays.) Based on what I have seen, I don't like the book. (But could change my mind, I suppose, when I see the whole thing in final version.)

    It does seem to have at least one chapter that considers what you might think of as "self-creation", but I can't say how seriously that is taken nowadays.
    There are so many other ideas which are more concrete, more physical. And some may be testable in the sense that the way expansion started could have left an observable imprint on the distribution of matter and radiation.

    As long as these concrete ideas are on the table, for understanding how expansion started, it seems unnecessary to spend time with anything as speculative and philosophically bizarre as self-creation. My attitude anyway, you may feel differently.

    In case anyone is curious, here's a link to the publisher's page about that book:
    http://www.springer.com/astronomy/general+relativity/book/978-3-540-71422-4 [Broken]
    It gives a link to the table of contents, and another link to some reviews, and it gives a list of keywords---which indicates some of the topics covered in the various 20-odd chapters:

    ==quote from publisher's page, warning: contains blurb==
    "The stellar line-up of contributors to this volume are working at the cutting edge of cosmological research, and are poised to take our understanding of the universe beyond the big bang into an even stranger realm." -- Paul Davies
    "This book provides a wonderful overview of current ideas on these ultimate cosmic questions, written by scientists working at the forefront of cosmological research."-- Alex Vilenkin

    Written for:
    Popular/general

    Keywords:
    Anthropic Principle
    Before the Big bang
    Big Bounce
    Cosmic Inflation
    Cosmic Initial Conditions
    Cosmic Natural Selection
    Cyclic Universe
    Eternal Inflation
    Holographic Universe
    Island Cosmology
    Loop Quantum Gravity
    Quantum Cosmology
    String Cosmology
    String Landscape and Multiverse
    ...
    ==endquote==
     
    Last edited by a moderator: May 4, 2017
  11. Jan 23, 2010 #10

    DevilsAvocado

    User Avatar
    Gold Member

    The most important (< 1998) parameter in fate of the universe is the Density parameter, Omega (Ω), defined as the average matter density of the universe divided by a critical value of that density.

    Omega (Ω) related to the curvature of space (global geometry, all forms of dark energy are ignored):
    360px-End_of_universe.jpg
    Ω > 1 positive curvature, spherical universe, Closed
    Ω < 1 negative curvature, hyperbolic universe, Open
    Ω = 1 zero curvature, flat universe, Flat

    A closed universe (Ω > 1), lacking the repulsive effect of dark energy, gravity eventually stops the expansion of the universe, after which it starts to contract until all matter in the universe collapses to a final singularity, "Big Crunch". However, if the universe has a large amount of dark energy (as suggested by recent findings), then the expansion of the universe can continue forever.

    An open universe (Ω < 1), even without dark energy, expands forever, with gravity barely slowing the rate of expansion. With dark energy, the expansion not only continues but accelerates. The ultimate fate of an open universe is either "Heat Death", "Big Freeze", or the "Big Rip".

    In a flat universe (Ω = 1), average density of the universe exactly equals the critical density. Without dark energy, it expands forever but at a continually decelerating rate, approaching a fixed rate. With dark energy, the expansion rate of the universe initially slows down, due to the effect of gravity, but eventually increases. The ultimate fate of the universe is the same as an open universe.

    The options then are:
    • Big Freeze
    • Heat death
    • Big Rip
    • Big Crunch
    • Big Bounce
    • Multiverse (no end)
    • False vacuum (destroyed instantaneously)
    As an 'answer' to OP, the only options (as I see it) not demanding a 'caused start', is the Big Bounce, and maybe Multiverse...
     
  12. Jan 23, 2010 #11

    DevilsAvocado

    User Avatar
    Gold Member

    And if BB is proved a onetime event, then the obvious question is – So what created "whatever state existed a prior to that"...??

    And we’re back to Catch-22 again... a philosophical loop without a logical end...

    In my opinion, the best thing to do is to wait for science to (hopefully) discover a theory that takes us all the way back to t0. And then hope that this 'TOE' is 'self-explainable', in case of t0 as the absolute first 'moment' in all spacetime... if we are lucky...
     
  13. Jan 24, 2010 #12

    Chronos

    User Avatar
    Science Advisor
    Gold Member

    In a temporally finite universe, the issue of a beginning is inescapable. Whether that beginning is literal is open to interpretation. This universe could be a temporally finite patch on the surface of a much larger [perhaps infinitely large] region that is unobservable to us. Deriving the value of omega is an important goal of modern cosmology. If it turns out the universe is closed, it is almost certainly finite in time and space. If not, it is probably infinite in both regards.
     
  14. Jan 24, 2010 #13
    No, I can provide an example.
    "Big bounce" scenarios, for example. Universe contacts from infinity, bounces, and exands again. I really don't like the interpretation that Universe "contracted", because it requires some magic event when entropy suddenly decreased.

    I think it is much more easier to interpret the contraction as expansion, so entropy decreased all the way down to the BB. It means, that for all observers in such Universe time time flowed FROM the BB, like in ours. So it is a symmetrical double-sided BB.

    In MWI, as all possibilities exist, it means that wavefunction of the universe, "omnium", O(t) is an even function, O(-t)=O(t), so both sides are identical -> they are the same.
     
  15. Jan 24, 2010 #14

    Chalnoth

    User Avatar
    Science Advisor

    Nope. Self-causality is certainly strange, but it is not illogical. That is to say, there doesn't appear to be any logical contradiction posed by the possibility of self-causation. It is definitely strange, however. In quantum mechanics, one could see loop contributions to Feynman diagrams as being self-caused.
     
  16. Jan 24, 2010 #15

    DevilsAvocado

    User Avatar
    Gold Member

    Okay (warning I just finished a full course at the http://www.youtube.com/watch?v=kQFKtI6gn9Y" :smile:), so how does one explain this 'little' dilemma:

    If BB is a single event, and time and space were 'created' at t0 – How is it possible for QM/Feynman diagrams to 'choose' a moment, 13.8 billion years ago, to cause its own 'creation'? If there is No time – there are obviously No moments to 'choose' for a start... right??
     
    Last edited by a moderator: Apr 24, 2017
  17. Jan 24, 2010 #16
    What created (caused) number 7?
     
  18. Jan 24, 2010 #17

    DevilsAvocado

    User Avatar
    Gold Member

    Number 3 & 4 ...? :uhh:
     
  19. Jan 24, 2010 #18

    DevilsAvocado

    User Avatar
    Gold Member

    I absolutely agree.

    Agree. Or as http://bloggingheads.tv/diavlogs/21709?in=27:40&out=30:00": "If you took our universe today and you let it collapse, instead of winding the clock backwards, you just reversed its expansion and let it collapse – it would not undergo the time-reversal of the ordinary evolution of the universe from early to late – it will be very very different!"

    I don’t get this at all... how can contraction be 'interpreted' as expansion... :confused: to me this is running time backwards, even in MWI...

    But couldn’t one explanation to the very special initial conditions at BB be 'some new' physics at Planck time, that we yet don’t understand... i.e. in a "Big Bounce" the universe starts to collapse, and when GR breaks down at Planck time, some 'new processes' comes in and reorder the entropy into a level that a new BB can occur, and this is then repeated infinitely...? Or is this just 'layman science fiction'...?

    Another possibility (maybe) can be that for every "Bounce" there’s completely new/different initial conditions, thus every BB creates a completely unique (laws, particles, etc) universe...
     
    Last edited by a moderator: Apr 24, 2017
  20. Jan 24, 2010 #19

    Chalnoth

    User Avatar
    Science Advisor

    Why not ask that question for a nuclear decay? How does, for instance, a Uranium 238 nucleus 'choose' one moment to decay as opposed to another?
     
    Last edited by a moderator: Apr 24, 2017
  21. Jan 24, 2010 #20

    DevilsAvocado

    User Avatar
    Gold Member

    I think you misunderstood me, and/or vice versa.

    Uranium 238 decay is cool. The random nature of QM (and absence of cause) is cool. HUP is cool, because: There already is a framework where these phenomena can operate/progress – Space+Time.

    This problem is quite simple, and has nothing to do with cause or QM or anything like that. It doesn’t matter if it’s Feynman, Einstein, Shaman, Bhagavan, or any other distinguished gentleman – they all have the same 'single' problem:
    Feynman – "I wanna run 100 meters."
    Einstein – "Sorry Dick, I’m not gonna let you do that..."
    "Why?"
    "Because we don’t have any meters in this place..."
    "What!?"
    "Nope..."
    "Ehh screw it… I’m gonna let my QM foam out NOW... so the QFT and my diagram can start The Universe randomly without a cause... so I can get a drink and my Nobel Prize later... 13.8 billion years later..."
    "Not gonna let you do that either..."
    "What!? Why!?"
    "Because you don’t have any time, and thus no NOW, to do it..."
    "Say What!? Time is all we got in this darned place!!"
    "Sorry Dick, no time and no space... it’s just you & me, and the virtual eternity..."
    Get it? :wink:
     
  22. Jan 24, 2010 #21

    Chalnoth

    User Avatar
    Science Advisor

    I merely pointed out that in quantum mechanics, there are a large number of events that are "uncaused" in a sense: they have a certain probability per unit time of occurring, but they don't occur at a certain time because of a certain event.

    It's not difficult to imagine that this process might well extend to space-times in quantum gravity.
     
  23. Jan 24, 2010 #22

    DevilsAvocado

    User Avatar
    Gold Member

    It’s cool, I misunderstood you. So, any thoughts on the "Feynman-Einstein dialog", right or wrong?
     
  24. Jan 24, 2010 #23
    Correct me if I'm wrong but quantum mechanics doesn't allow for an event without a cause and even virtual particles occur because the potential for their occurrence is contained in the relevant lagrangian, what QM does allow is a cause w/o necessarily an effect eg: throwing a particle at a barrier may or may not cause it to reflect back
     
  25. Jan 24, 2010 #24

    Chalnoth

    User Avatar
    Science Advisor

    I don't understand at all what you were getting at.
     
  26. Jan 24, 2010 #25

    Chalnoth

    User Avatar
    Science Advisor

    Well, there is a cause in the sense that there are laws of physics which provide the potential for certain interactions to occur, and so they do with some frequency. It isn't difficult to imagine that the same sort of thing might occur for space-times. This isn't the same cause-and-effect relationship, though, as it's not a matter of some event occurring which causes some other event. Instead it's just that X happens because the laws of physics are a certain way. So self-caused is perhaps a somewhat better description than uncaused (e.g. in the instance of a virtual particle, virtual particles appear because they have certain interactions with other bits of matter).
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook