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Big Bang or Cosmic Crunch?
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."
Hobbes: "Well what would *you* call the creation of the universe?"
Calvin: "The Horrendous Space Kablooie!"
Quidquid latine dictum sit, altum sonatur.
then perhaps Nietzsche was right after all, as I've said infinitely many times before.
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?
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...
Here's a summary. I don't have the book any more so I can't quote, but notice in the summary of chapter 10 where the summary reads "When shrinkage to below the Planck length is attempted, the crunch becomes a bounce."
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.
(Disclaimer: IANAP, although I'm enamoured with the topic.)
It's not just subatomic particles that slow down, which is Einstein's true stroke of brilliance. Einstein began down the road of Special Relativity by postulating that Newton's Principle of Relativity -- no matter where you are in the universe, the laws of physics are the same for all inertial (constant velocity) frames -- is correct. One of the laws of physics, courtesy of Maxwell's Equations, requires that the speed of light in a vacuum, c, is a constant. So, if both of these postulates are correct, then everyone will agree on the value of c in all inertial frames.
This deserves some illustration. Suppose you're on a hypothetical train traveling at a constant velocity of 0.5c towards a friend, and you point a flashlight straight forward and turn it on. You perceive the beam of light as traveling toward your friend at speed c; however, your friend sees the beam of light as traveling toward him at speed c, and not speed 1.5c. How can this be?
The answer that Einstein came up with, and the only known set of physical laws of motion that is consistent with both Maxwell's Equations and the Principle of Relativity, requires that your friend sees you as flowing through time at a slowed rate, whereas you see him as the one who is slowed down. With some extra geometry not far beyond a high school math student, it's not hard to prove that the length of (you|your friend) must contract; also, some modifications to Newton's Laws are required in order to make the laws of inertia and momentum self-consistent, making (you|your friend) appear to have more mass.
It is an inescapable conclusion of Special Relativity that the actual flow of time slows down -- General Relativity, the theory which tied SR and gravity together while introducing time as a 4th dimension, is not even required to prove this result. The very CRT that you're using to view this article right now could not possibly exist if Maxwell's Equations were grossly wrong, meaning the only way to prove SR grossly wrong about the flow of time would be to disprove the Principle of Relativity -- by demonstrating that the laws of physics vary depending on where you are in the Universe!
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This makes perfect logical sense to me. Why would time have a beginning OR ending? Just because human lives have them?
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...
.sig you've ever seen.
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