Black Crunch jams Universal cycle [Cosmology]

Nature Magazine ^ | 23 Decemeber 2002 | PHILIP BALL

[PatrickHenry]

Space might end up dark, thick and boring.

The Universe is not as bouncy as some think, say two physicists. If a Big Crunch follows the Big Bang, it may get stuck that way for ever¹.

A fluid of black holes would bung up space. There would be nothing to drive another Big Bang, and nowhere else to go. The Universe would be, you might say, stuffed.

In a bouncing universe, all the matter currently flying apart slows until it reverses and falls towards a Big Crunch. Some physicists think this could ignite another Big Bang, in an unending sequence of expansion and contraction.

An idea called M-theory suggests how the switch from crunch to bang could happen². The details depend on the shape of space: whether it is infinite and flat, or finite and curved like the surface of a balloon or a doughnut.

Thomas Banks of Rutgers University, New Jersey, and Willy Fischler of the University of Texas at Austin have considered a flat, infinite space in which particles get ever closer and ever denser.

In a space with such features, the smallest kinks in density are amplified into black holes, the densest objects in the Universe. So the whole of space-time would congeal into a very lumpy soup - a black crunch.

"We don't really know what this fluid is made out of," Fischler admits. But he and Banks argue that it may reach a pressure at which it cannot become any denser. At this point, the speed of sound equals the speed of light. Deadlock results.

No theory can cope with a Big Crunch. Because of this, says Fischler, the analysis that he and Banks have performed remains speculative. And a doughnut-shaped Universe could meet a quite different fate, he adds.

References:

1. Banks, T. & Fishler, W. Black Crunch. Preprint http://xxx.lanl.gov/abs/hep-th/0212113, (2002). |Article|
2. Khoury, J., Ovrut, B. A., Seiberg, N., Steinhardt, P. J. & Turok, N. From Big Crunch to Big Bang. Preprint http://xxx.lanl.gov/abs/hep-th/0108187, (2002). |Article|
[See the original article for links in the footnotes]

[MHGinTN]

Party pooper.

[Physicist]

The moon is slowing down, but it's getting higher. Explain that.

[Physicist]

5 cubed root..

<shakes head>

[RightWhale]

Sorry, I printed out the actual scientific articles. There is a lot of math and stuff, but a lot of commentary as well, some of which raises questions for further theoretical research. A merry string metric and happy stress tensor to you.

[MHGinTN]

May all your branes remain safe through the holidays, RW.

[Doctor Stochastic]

I know some people who slow down as they get higher.

[general_re]

I know some people who slow down as they get higher.

That sounds familiar - reminds me of a few weekends I had in college. My memories are rather fuzzy, but semi-reliable witnesses assure me that I had a good time...

[MacDorcha]

oh, for God's sake, cut me a little slack. i said in the first one that the answer was 8.6(something) ft up. i also said "cubed root" instead of "10 times the square root of three" i came up with the right answer, and you know how simple a mistake that is to make. it's been 7 months since i've heard any of that crap. gimme a freakin break.

[MacDorcha]

now if i knew that, i would know more than the professionals who claim to be getting more info on this stuff. there are a few theories on how it got there, all of which don't fully explane the pulling away, except maybe the gravitational pull of other bodies in the system, but that's a reach if ever there was one. simplest way i can put it? the energy is being lost, and it is going to the place acting the most on it.

[RadioAstronomer]

RadioAstronomer, you are a class act.

Thank you :-)

[Physicist]

you know how simple a mistake that is to make.

Like confusing lightning with a lightning bug.

it's been 7 months since i've heard any of that crap.

I hope you take more challenging courses next semester. But in any case, I hope you're prepared to retain "that crap" for longer than seven months at a stretch when you get to the real world.

gimme a freakin break.

No chance. You were the one who came out swinging and bragging about how smart you were. Don't talk the talk if you can't walk the walk.

[Physicist]

now if i knew that, i would know more than the professionals who claim to be getting more info on this stuff. there are a few theories on how it got there, all of which don't fully explane the pulling away, except maybe the gravitational pull of other bodies in the system, but that's a reach if ever there was one. simplest way i can put it? the energy is being lost, and it is going to the place acting the most on it.

Do you want to hear the correct answer? No energy is being lost; as a matter of fact, the moon is gaining orbital energy. It does this because of tidal pumping by the Earth's oceans sloshing back and forth. The energy ultimately comes from the rotation of the Earth, which slows down slightly. The total energy (and angular momentum) is conserved.

A pendulum won't gain or lose energy by this process. In the first place, the motion of the pendulum is not phase-locked to the motion of the ocean, as it is in the moon's case. In the second place, the tidal force over the swing of the pendulum is extremely small, while it is large for the moon.

Gravity is a conservative force. If the oceans didn't slop about, the moon would stay in its orbit for all eternity. In the absence of friction, a pendulum will swing with the same energy--meaning, to the same height--forever. (A vacuum will take away most of the friction; a magnetic bearing will take away the rest.)

[PatrickHenry]

gimme a freakin break Placemarker.

[PatrickHenry]

... a class act.

Some of us know you.

[MacDorcha]

i came out swinging to defend myself. in case you didnt notice, i was being attacked by others, and your sarcastic ass wasnt exactly welcome. i "bragged" so you knew that even if i was wrong, i am capable. in other words, try helping someone if you honestly think they are wrong. dont smear your almighty babble on me if you want me to listen. i know i have been baabling at you as well, but my points arent being listened to in here anyway, so i got nothing to lose, but if you want to even resemble a respectable person, you may wanna try a new approach.

"Like confusing lightning with a lightning bug."
now, i understand not all analogies are perfect, but is that REALLY the closest you could get? no wonder i think your methods are bunk.

[Physicist]

i was being attacked by others

No, you were being corrected by others. The proper response to that is "thank you".

[Doctor Stochastic]

He can walk the talk, but he can't run the gun because he doesn't understand the hand. (Stephen Cannell)

[RadioAstronomer]

Good grief. I sure hope this is not the norm.

[MHGinTN]

I once had a task that took me into jails and prisons on occasion. This poster trying to 'shuck and jive' science and math sounds more like the typical inmate than a college student. Bluster used to conceal ignorance. Incidentally, many of the inmates were very intelligent, but bone-ass lazy when it came to apply their intelligence to learning the necessary data for true competence.

[longshadow]

---

i came out swinging to defend myself. in case you didnt notice, i was being attacked by others, and your sarcastic ass wasnt exactly welcome. i "bragged" so you knew that even if i was wrong, i am capable. in other words, try helping someone if you honestly think they are wrong. dont smear your almighty babble on me if you want me to listen. i know i have been baabling at you as well, but my points arent being listened to in here anyway, so i got nothing to lose, but if you want to even resemble a respectable person, you may wanna try a new approach.

Hey, Mac; it sounds better when you put it to music:

---

IT'S HARD TO BE HUMBLE
(Mac Davis)

cho: Oh Lord, it's hard to be humble,
When you're perfect in every way
I can't wait to look in the mirror,
'Cause I get better lookin' each day
To know me is to love me,
I must be a hell of a man
Oh, Lord, it's hard to be humble,
But I'm doing the best that I can

I used to have a girlfriend,
But I guess she just couldn't compete
With all of these love-starved women,
Who keep clamoring at my feet

Well I prob'ly could find me another
But I guess they're all in awe of me
Who cares, I never get lonesome,
'Cause I treasure my own company.

I guess you could say I'm a loner,
A cowboy out-law, tough and proud
Oh, I could have lots of friends if I want to
But then I wouldn't stand out from the crowd

Some folks say that I'm ego-tistical
Hell, I don't even know what that means
I guess it has somethin' to do with the way
That I fill out my skin-tight blue jeans.