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]

[Physicist]

i happen to be in college, and could not have gotten there without passing algebra, geometry, and trigonomitry.

I can tell you from hard experience that the typical undergraduate is stone ignorant of these subjects. I'll grant that they may have passed them, however.

[longshadow]

if there is an explosion of universal proportion that is causing us to fly into oblivion at untol speeds, it must have a center.

Ah, but is space itself is what is expanding, then there is no "center," is there?

[MacDorcha]

ok, go on assuming that this is it, and that's all there is. Voltaire is your man. as for me, i think, therefor, i am. i can percieve what reality would be, i can percieve what perfection would be. although i cannot fully understand it, i can grasp the idea of infinity. sense i can do all these things, they must be, since i can grasp the idea of God, He must be.

by playing the silly mind games, you can get over things such as "life is meaningless" (as i am sure you follow, seeing as how you seem to think that once we die, there is no-where else to go, and all our accomplishments will fall) if you follow the actual words of what you say, it's depressing. but you seem to feel man will know everything about everything. if this is true, you will know that man knows that depression is the product of a faulty mindset. you go through life, dont you? there are more things to life than eventual nothing, isnt there? if man is capable of knowing all, it will know that a system designed to die, makes us all useless, which means we should have killed ourselves off long ago. there is, and always will be, more to existance than math and theories.

[MacDorcha]

the furthest point from all sides. center.

[Scully]

I can tell you from hard experience that the typical undergraduate is stone ignorant of these subjects.

I'll second this - most of my students didn't even have a clue as to what friction is. And yes, I chose a subject near and dear to their hearts to explain friction. They finally got the concept. (But good grief! We are speaking of "College" students!)

[Physicist]

I'll second this - most of my students didn't even have a clue as to what friction is.

I don't expect an incoming student to know what friction is. I had to train myself to stop expecting that they know what sines and cosines are, beyond too-convenient buttons on their calculators. A problem like, "there's a 10-foot ladder propped at a 60-degree angle against a house; how high does it reach?" is quite beyond most freshmen.

[Sentis]

MacDorcha wrote ". if this is true, you will know that man knows that depression is the product of a faulty mindset. you go through life, dont you? there are more things to life than eventual nothing, isnt there? if man is capable of knowing all, it will know that a system designed to die, makes us all useless, which means we should have killed ourselves off long ago. there is, and always will be, more to existance than math and theories."

I didnt realize how young you were when I began posting to you. I will refrain from shredding this post to pieces as your use of the word depression in it several times it makes me a little hesitant. Your young your world view is forming I do not want to be the one who pushes you away from rational thought because I attacked you.


I know what your going through I was there. I once stood on the same precipice considering the world with No God, No Heaven, No crutches to keep me strong and safe from the universe. I looked inside myself and found the strength to step away from the mythology, the lies, and the crutch. I found myself alone in a world where I as a conservative, atheist was not welcome. This could have lead to serious depression but the strength was there for me because I believed in myself and my abilities. I could form my own beliefs I could stand on my own.

[longshadow]

the furthest point from all sides. center.

And if space itself has no boundaries, it has no "sides" from which to define a center.

[Doctor Stochastic]

You are looking at things the wrong way. The universe isn't expanding into anything. It's the universe itself that is expanding.

You should study some elementary astronomy and cosmology to get an idea of what current theory is.

[Doctor Stochastic]

You haven't studied topology much; at least by what you have been posting. Thus, your mistake about the circle. A circle is a one-dimensional object of constant curvature. There is no straight line joining any two points as you were claiming.

All this goes back to Gauss (and later Riemann.)

[Doctor Stochastic]

...sub-atomic particles float freely, and are not suspect to gravity...

Sub atomic particles are the usual suspects in physics. (If you meant that they are not subject to gravity, you are just wrong.)

[MHGinTN]

In a 'black hole', time and space are also being gobbled up with the masses 'falling' into the gravity well. Hawking theorizes that the event horizon 'sweats' radiation back into our universe, back into our spcaetime.

If considering the crunch of our spacetime and masses (like a huge black hole), as the event horizon becomes the 'out there' with no more out there beyond the event horizon of the final 'hole', there is no place for this energy to sweat to ... this beast has yet to be mathematically defined so it is not possible to yet calculate what will happen when the universe crunches (if the universe does). As Physicist cited, the spacetime bubble appears to be speeding up in its expansion, so the likelihood of gravity from existing masses stopping then reversing the expansion appears to also be out.

The eventual cold final destiny appears to be in the future at about 10 to the 120th power years away. For science to change this perspective, some other means to transfer the energy radiating from black holes (or perhaps some other energy radiating by some means other than x-rays and into a quantum well outside our spacetime) will have to be theorized so that even if the crunch runs, it can culminate in some where/when.

With the initiating event of the 'big bang' space, time, and energy were involved in the expansion. The inflationary phase would have stretched the spacetime bubble much faster than light speed, but at some where/when the inflation would slow and the colled spacetime bubble would allow condensation of intitial masses (those sub-atomic building thingies that form sub-atomic particles of protons and electrons and neutrons). Much later the cooling would allow for first atoms to form and gravity would begin to act in the spacetime bubble.

There is no 'center' to the spacetime bubble, per se, but if we run the expansion backwards, there does appear to be a mathematical where/when which was the initial bang event. The term bubble is somewhat misleading because the universe of spacetime isn't really 'spherical', per se, even though running the expansion backwards evidences a common where/when for the start. When science refers to the 'shape' of the universe, it is in reference to the mathematical curvature or non-curvature rather than a volumetric shape since this curvature is to be thought of as having an element of dimension time integrated into the curvature.

[MHGinTN]

Thank you for the ping, by the way.

[RadioAstronomer]

"there's a 10-foot ladder propped at a 60-degree angle against a house; how high does it reach?" is quite beyond most freshmen.

Spooky :-(

[MHGinTN]

An average carpenter could figure it.

[MacDorcha]

then please, explane a radius. thats part of a circle. and it has two points. or better yet, a diameter. how does one find the dimensions of a circle? gee... pie times the raidus.... squared i think.... yes, it's squared. and becuase you use it, it is part of it. keep trying though, your attempt shows how long you've been out of school.

[MacDorcha]

i know my abilities. other wise, i wouldnt be so damned bull headed. i am sorry, but your story doesnt move me.

[MacDorcha]

if it has no sides, how do you know it's expanding? how do we know it isnt just some phenomonom that causes movements around us? or... that this system is contracting? saying it has no sides down plays the big bang theory

[MacDorcha]

oh, and btw. i proved gravity, not air-resitance. lock th device in a vacuum. it will still stop, and it will never reach the same height without assitance. the force down is greater than the force out or up.

[RadioAstronomer]

how does one find the dimensions of a circle? gee... pie times the raidus.... squared i think.... yes, it's squared. and becuase you use it, it is part of it. keep trying though, your attempt shows how long you've been out of school.

Pi * r² (pi times radius squared) or pi * d (pi times diameter)

Depends if you are looking for area or diameter. Once you understand Dimensional Analysis you will never get them confused again. Now it gets a bit tougher (not much :-)) if you are looking for the area of a paraboloid or hyperboloid like what I use in my work.