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."

Comments

Read about this in the Elegant Universe....

[anthony_dipierro]

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."

Re:Infinity is a very difficult concept to even..

[CTachyon]

(Disclaimer: IANAP, although I'm enamoured with the topic.)

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....

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!