Posted on 05/24/2006 3:59:24 PM PDT by LibWhacker
Scientists use quantum gravity to describe the universe before the Big Bang.
Scientists may finally have an answer to a "big" question: If the Big Bang was the beginning of the universe, what could have caused it to happen?
Using a theory called "loop quantum gravity," a group led by Penn State professor Abhay Ashtekar has shown that just before the Big Bang occurred, another universe very similar to ours may have been contracting. According to the group's findings, this previous universe eventually became so dense that a normally negligible repulsive component of the gravitational force overpowered the attractive component, causing the universe to "bounce" apart. This big bounce is what we now know as the Big Bang. The group published its analysis in the April 12th issue of Physical Review Letters.
"These equations tell us that in fact there is another pre-Big Bang branch of the universe, and then we tried to understand what it looks like," Ashtekar said. "[Surprisingly], the universe again looks very much classical.
"So there is another universe on the other side which is joined to our universe in a deterministic way," he concluded.
Coauthor Parampreet Singh, a postdoc at Penn State, said that Einstein's theory of general relativity describes the current universe very well, but it breaks down when it encounters the extreme density of the universe around the time of the Big Bang.
"[General relativity] gives physical singularities when we ask questions about the physics near the Big Bang," he said. "Unless this problem is solved, or unless a solution of this problem is known, we do not have a complete description of the universe."
Physicists have developed theoretical systems, such as string theory, to unite general relativity with quantum mechanics and explain the very early universe. In the late 1980s, Ashtekar published the first paper on loop quantum gravity, a theory which applies quantum mechanical principles to examine the spacetime continuum. According to his model, there is no continuum: Smooth, continuous space is only an approximation of an underlying quantized structure, one that is made up of discrete units.
Loop quantum gravity also predicts a small repulsive component of gravitational force, which is a non-factor in other theories. At most densities, even the extremely high density of an atom's nucleus, this component has no significant effect. But as density increases, approaching 1075 times the nuclear density, this repulsion begins to dominate. According to the Ashtekar's equations, this appears to be what happened to the universe before ours: As it collapsed, it became so dense that gravity started to, in a sense, work backwards, birthing our universe.
Singh, Ashtekar's postdoc, noted that the group's conclusions are eerily similar to findings published by Princeton researcher Paul Steinhardt two weeks ago. Using string theory, Steinhardt concluded that the universe may be cyclic, with each crunch leading to a bounce.
But Steinhardt said the two papers are only distantly related:
"It is an idealized set-up which does not connect smoothly to realistic cosmology," he said via e-mail about the Penn State paper. "By contrast, our scenario is designed so that it connects smoothly to Einstein gravity and standard Hubble expansion, so that it reproduces the astronomical conditions we observe today."
Ashtekar acknowledge that his work addresses the idealized situation of a homogeneous, isotropic universe, one that is uniform in space and uniform in all directions—the model does not account for heterogeneities such as galaxies.
"This picture does hold up in kind of simple generalizations," he said. "The key question is really if this prediction is going to hold up with more and more realistic models."
The heavier elements are created in supernovae. Every atom in your body, except for the hydrogen, has been through a star at least one time.
BTTT
I was asked that question in High School theology class years ago. My smart-ass answer was "the same place God came from"
A cyclical universe would have no beginning nor end, just big-banging, expanding, contracting, and big-banging again
Aha!... But how many stars has the average atom been through?
So, how did this start? Or did it have no start, but has been oscillating in this fashion for eternity? How can we know?
What is the technical explanation for God's creation of the Universe?
Who knows? But that's where the little buggers are assembled.:-)
Talk about mythology. Back to infinite regression.
Would you not get more defined results by peeing in the wind.
I'm not sure where you're getting this but I'll accept it for the sake of argument.
That doesn't match reality, because we have tons of Silicon, Carbon, Oxygen, Nitrogen, Copper, Zinc.
Right. Carbon, Nitrogen, Silicon, and Oxygen are all way lower in the Periodic Table than Iron, so adopting your theory, you would expect them to be more plentiful. Copper and Zinc are in the same row. Titanium and Vanadium are actually LOWER than Iron in the PT. So you would expect them to be MORE abundant, but in fact they're relatively rare.
As you move up the Periodic Table, the frequency of these elements get more and more rare.
And they do, generally speaking. So you've just defeated our own argument. Or did I misunderstand something?
...and where did that come from, and where did that come from, and that one and that one?
"Scientists" study things they claim are trillions of years old...and never come up with an answer, just postulation. As much proof as we can come up with for there being G-D. I'll stick with my postulation and..."excuse me while I kiss the sky".
FMCDH(BITS)
This is polite language.
Yes. I can attest to that, although peeing into the wind is much more defining.
FMCDH(BITS)
Kids playing with matches.
Billion of years old, not trillions. But the rest is correct. But what would you expect? To expect anything else is to not understand how science works. To explain why is in the realm of philosophers.
I wish I was smart enough to figure this crap out for free.
Yeah, but look on the bright side: at least this proves we're all into recycling in a big way. )
I think our Medical Professionals understand this quite well. Would you like me to point out some web sites for you?
ping
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.