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Big Bang or Cosmic Crunch?

Posted by timothy on from the with-nougat-caramel-and-turkish-delight dept.

BrianGa writes: "Yahoo news is reporting on Princeton University physicist Paul Steinhardt suggesting that the universe never began and will never end, driven forever to expand in a series of monster explosions and contract every eon or so in a cosmic crunch. This is directly contradictory to the big-bang theory. The model of the universe envisioned by Steinhardt sees the big bang as merely a turning point on an infinite road."

6 of 94 comments (clear)

  1. Not a new theory by quadong · · Score: 3, Interesting

    This is hardly a new theory. The only thing which I see that makes it distinct from the age-old theory with the same outline is that it invokes dark matter as part of the mechanism. Hopefully, if presented in scientific language rather than yahoo-interview, it has some interesting new twist, but I'm just not seeing it here.

    Also, he says "When it's changing slowly, it's gravitationally self-repulsive and when it's changing fast, it picks up speed, it's gravitationally self-attractive". It's slow and repulsive now. What is supposed to ever make it speed up in the future since it's own existance is what is making it slow now?

  2. The Ekpyrotic Theory... by cybrpnk · · Score: 5, Interesting

    There's a lot of theories about alternatives to the big bang besides the one mentioned in the Yahoo article. The main one that is getting a lot of interest in scientific circles isn't this new one in the Yahoo article. Instead, it's the so called Ekpyrotic theory, with the name coming for the Greek word for fire. It is so intresting because it brings together two disparate areas of physics: inflation and M branes. Inflation is a weird concept that says the universe expanded from the diameter or an atom to the size of a grapefruit almost instantly - required to explain the way galaxies are clumped and clustered in the sky we see today and first postulated by a guy named Alan Guth. M branes are an offshoot of string theory postulated by Ed Whitten. There's tons of stuff on these topics on the web; all of it is facinating, enter any of these terms in a search engine and keep reading. Next stop, Google...

  3. Re:Infinity is a very difficult concept to even.. by Anonymous Coward · · Score: 1, Interesting

    Humans are starting to think of the universe in wrong ways. My main beef is with time. People think of time as a physical dimension that is effected by matter.... this, is only partially true.

    They have sent up jets with atomic clocks to test einsteins theory of gravitation effecting time, and they think of it to be correct. The more gravity, the slower time moves. But is it really making a change to some 4th dimension, or just the speed at which the subatomic particles within matter move? ....the latter is certianly acceptable. Since matter slows down, then "time" relative to that slowed matter would infact slow....

  4. Lee Smolin's ideas make a lot more sense by ynotds · · Score: 3, Interesting

    Lee Smolin talks about an evolutionary model in The Life of the Cosmos which has the great advantage, for those who can get their head around it, of not requiring any assumptions about special conditions just arising out of nowhere, which is to my mind indistiguiushable from always having been there.

    Because we can't really escape them here, we have a lot of trouble contemplating anything at all which does not involve space, time, energy nor matter. An evolutionary universe gets us past this, not because it is concerned about survival, but about fecundity of the production process whereby black holes rebound to form disconnected big (and maybe sometimes little) bangs, then extrapolating this process back till when there was truly nothing except the possibility.

    Granting William of Occam an oversized razor, it would surely favour Smolin's idea of evolution from a state where the only certainty is that nothing is unstable to the world we find ourselves in; rather than Ekprotic Theory, any of the many attempts to revive the steady state corpse, the quantum theorists' many world interpretation or "intelligent design".

    Cycles never truly come back to their starting point.

    --
    -- Our systemic servants do not good masters make.
  5. I've always said this. by juju2112 · · Score: 3, Interesting
    I don't know much about physics, but i've always thought this. Really he's not disputing the Big Bang theory at all. He's saying that while it did occur, it was not the beginning of time. He's saying that in fact time has no beginning, or ending.


    This makes perfect logical sense to me. Why would time have a beginning OR ending? Just because human lives have them?

  6. A Brief History of Time by bheilig · · Score: 3, Interesting

    I read this book by Hawking some time ago; I make no claims about understanding it. He mentioned several logical possibilities, which should summarize what everyone else has been saying in spurious posts...

    1. A beginning with no end. Our universe began from the big bang and, if the gravitational pull of the center is not large enough to overcome the momentum of the explosion, will continue to expand though infinity.
    2. A beginning with an end. The gravitational pull of the center can overcome the momentum of the explosion, resulting in a big crunch.

    These two only describe our observable universe. Time begins with each explosion and ends with each contraction. If the gravitational pull, which grows as the universal spheroid becomes more massive, can pull the mass smaller than infinitesimal (mathematically speaking, I guess) then a bounce occurs, resulting in another explosion.

    3. If the ratio of energy/mass remains constant with each explosion, then THE universe (not OUR universe) continues from -infinity to +infinity, as the article states.
    4. If the ratio increases every time, the explosion will eventually provide enough momentum to overcome the pull of gravity (case 2). We may be in this state now, or we may not.
    5. If the ratio decreases every time, then eventually the universe will be pulled into a point, with just enough energy to keep it there. Our universe may have this finite end, or it may not.

    This is the greatest .sig you've ever seen.