Posted on 03/16/2005 11:59:50 AM PST by PatrickHenry
Why is the universe expanding at an accelerating rate, spreading its contents over ever greater dimensions of space? An original solution to this puzzle, certainly the most fascinating question in modern cosmology, was put forward by four theoretical physicists, Edward W. Kolb of the U.S. Department of Energy's Fermi National Accelerator Laboratory, Chicago (USA): Sabino Matarrese of the University of Padova; Alessio Notari from the University of Montreal (Canada); and Antonio Riotto of INFN (Istituto Nazionale di Fisica Nucleare) of Padova (Italy). Their study was submitted yesterday to the journal Physical Review Letters.
Over the last hundred years, the expansion of the universe has been a subject of passionate discussion, engaging the most brilliant minds of the century. Like his contemporaries, Albert Einstein initially thought that the universe was static: that it neither expanded nor shrank. When his own Theory of General Relativity clearly showed that the universe should expand or contract, Einstein chose to introduce a new ingredient into his theory. His "cosmological constant" represented a mass density of empty space that drove the universe to expand at an ever-increasing rate.
When in 1929 Edwin Hubble proved that the universe is in fact expanding, Einstein repudiated his cosmological constant, calling it "the greatest blunder of my life." Then, almost a century later, physicists resurrected the cosmological constant in a variant called dark energy. In 1998, observations of very distant supernovae demonstrated that the universe is expanding at an accelerating rate. This accelerating expansion seemed to be explicable only by the presence of a new component of the universe, a "dark energy," representing some 70 percent of the total mass of the universe. Of the rest, about 25 percent appears to be in the form of another mysterious component, dark matter; while only about 5 percent comprises ordinary matter, those quarks, protons, neutrons and electrons that we and the galaxies are made of.
"The hypothesis of dark energy is extremely fascinating," explains Padova's Antonio Riotto, "but on the other hand it represents a serious problem. No theoretical model, not even the most modern, such as supersymmetry or string theory, is able to explain the presence of this mysterious dark energy in the amount that our observations require. If dark energy were the size that theories predict, the universe would have expanded with such a fantastic velocity that it would have prevented the existence of everything we know in our cosmos."
The requisite amount of dark energy is so difficult to reconcile with the known laws of nature that physicists have proposed all manner of exotic explanations, including new forces, new dimensions of spacetime, and new ultralight elementary particles. However, the new report proposes no new ingredient for the universe, only a realization that the present acceleration of the universe is a consequence of the standard cosmological model for the early universe: inflation.
"Our solution to the paradox posed by the accelerating universe," Riotto says, "relies on the so-called inflationary theory, born in 1981. According to this theory, within a tiny fraction of a second after the Big Bang, the universe experienced an incredibly rapid expansion. This explains why our universe seems to be very homogeneous. Recently, the Boomerang and WMAP experiments, which measured the small fluctuations in the background radiation originating with the Big Bang, confirmed inflationary theory.
It is widely believed that during the inflationary expansion early in the history of the universe, very tiny ripples in spacetime were generated, as predicted by Einstein's theory of General Relativity. These ripples were stretched by the expansion of the universe and extend today far beyond our cosmic horizon, that is over a region much bigger than the observable universe, a distance of about 15 billion light years. In their current paper, the authors propose that it is the evolution of these cosmic ripples that increases the observed expansion of the universe and accounts for its acceleration.
"We realized that you simply need to add this new key ingredient, the ripples of spacetime generated during the epoch of inflation, to Einstein's General Relativity to explain why the universe is accelerating today," Riotto says. "It seems that the solution to the puzzle of acceleration involves the universe beyond our cosmic horizon. No mysterious dark energy is required."
Fermilab's Kolb called the authors' proposal the most conservative explanation for the accelerating universe. "It requires only a proper accounting of the physical effects of the ripples beyond our cosmic horizon," he said.
Data from upcoming experiments will allow cosmologists to test the proposal. "Whether Einstein was right when he first introduced the cosmological constant, or whether he was right when he later refuted the idea will soon be tested by a new round of precision cosmological observations," Kolb said. "New data will soon allow us to distinguish between our explanation for the accelerated expansion of the universe and the dark energy solution."
INFN (Istituto Nazionale di Fisica Nucleare), Italy's national nuclear physics institute, supports, coordinates and carries out scientific research in subnuclear, nuclear and astroparticle physics and is involved in developing relevant technologies.
Fermilab, in Batavia, Illinois, USA, is operated by Universities Research Association, Inc. for the Department of Energy's Office of Science, which funds advanced research in particle physics and cosmology.
"Whether Einstein was right when he first introduced the cosmological constant, or whether he was right when he later refuted the idea..."
Einstein was right either way, then.
> that expansion either occurred in the past or continues to occur is not too much of a surprise...
Not to someone who can say that, no matter what happens either way, that his book of vague sayings covers it all.
In my mind, one of the unobservables amid the reality of the universe is "what existed before."
Assuming one subscribes to the theory of the big bang, the logical assumption is that matter would continue to expand outward from the initial singularity until inertia was bled off by gravitational attraction, and the whole of the universe would begin to rush in upon itself in a "big crunch." Indeed, this was the prevailing theory for many years.
My thought, however, is that we cannot observe what lies "beyond" spacetime, or the event horizon of our expanding universe.
In a small modification of Einstein's greatest blunder, the cosmologic constant, what if what "lies beyond" is devoid of a structural component that our material universe does not lack. Even an unobservable (to us) something in a dimension we cannot study. Is it beyond possibility that this creates a vacuum of sorts that pulls our universe into it? While vastly simplified, if one were to detonate a CO2 cartridge in a vacuum chamber, each molecule of CO2 would spread out from the point of release until every molecule had uniformly positioned itself within the chamber.
Maybe that is why the universe is expanding and at an ever faster rate. What lies beyond the border of our universe is aborbing our universe into it and a grand cosmic law of thermodynamics (used in allegory) is attempting to distribue time, space, and matter uniformly and thus exerts a pull.
But if that's true and what lies beyond our universe is infinite, then it will be a sad and lonly end for our universe as the distances beyond every object steadily increse until they are no longer observable to one another by any means at all.
Of course, I'm no physicist. Just the musings of a simple country boy.
No. Einstein added his cosmological constant to General Relativity in order to "prove" that our universe was static; neither expanding nor contracting.
Then Hubble's observations disproved Einstein's GR, prompting Einstein to label his "cosmological constant" as his greatest blunder.
Well, country boy, that "sad and lonely end" seems to be one of the likely scenarios, whether we're being sucked into a surrounding void or driven to expansion by the big bang. Either way, we're expanding into nothing. Oooops, there goes the Andromeda galaxy. Say goodbye ...
Actually there is a verse that says at the end of time, He will roll up the heavens like a scroll, so yes, I would probably say, "it's started". But that's only in there twice and there's something like 16 verses that say He "stretched" or "stretches" the heavens,
So your point is valid. Neither a current expansion, stasis, or contratraction would necessary contradict the scriptures. However, it is notable that the scriptures don't claim a "universe forever in stasis". It did have a beginning and will have an end.
Are they ridges, or waves, or particles??
If you wave it, it appears to have ridges. If you throw it, it is a particle. Which is why I am not rigid about theories - has bad ripple effect.
I remember getting ripples from pagan pink.
mc:>)
I like it! < :D
I read Simon Singh's interesting book "Big Bang", and while it was somewhat enlightening, it did not answer my simple question: If the big bang was not an explosion of matter in space, but rather an expansion of space and the matter within it from a single point, then how come they still talk about the universe as being infinite in extent. How come it is limited in terms of space at the time of the big bang and infinite now? I've read other articles which seem to say differing things -- either the universe is not infinite in space or that it was born in the big bang infinite in space. Why don't they get their story straight and think up an easy way to describe it for the layman?
We are a virus the universe is trying to stamp out.
Hence, Solar Coronas,Mass Coronal Ejections, Massive emanations from MAGNETARS, comets,earthquakes.
Obesity?
The real problem is physics.
Girth is determined by an individuals resistance to atmospheric pressure (ap). My resistance to ap is low therefore the pressure pushes on my surfaces making me appear slim. Fat people have a high resistance to ap so they spread out. Light people have a high resistance to gravity. Heavy people have little resistance to gravity.
Food has nothing to do with it. We can balance the scales by banning atmospheric pressure and gravity.
"Stop the atmospheric pressure and gravity now! It's for the children!"
CG
Math is the great divide. Or brick wall for most. It is nearly impossible to describe 11-dimensional space to anyone who lacks the math skills. Even with the math skills it is nearly impossible to visualize beyond four dimensions. They say that engineers have an ability to visualize three dimensions and that is not at all a common ability.
No, if you're saying that all matter was concentrated in one point from a three or four dimensional perspective, but that space was infinite in other dimensions, I can understand that. If that is the case, why don't they just say that? I fully understand that we can't really visualize more than three or four dimensions, but they can at least use understandable words to describe it.
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.