Posted on 05/08/2009 1:40:50 PM PDT by Mike Fieschko
Imagine a time when the entire universe froze. According to a new model for dark energy, that is essentially what happened about 11.5 billion years ago, when the universe was a quarter of the size it is today.
The model, published online May 6 in the journal Physical Review D, was developed by Research Associate Sourish Dutta and Professor of Physics Robert Scherrer at Vanderbilt University, working with Professor of Physics Stephen Hsu and graduate student David Reeb at the University of Oregon.
A cosmological phase transition -- similar to freezing -- is one of the distinctive aspects of this latest effort to account for dark energy -- the mysterious negative force that cosmologists now think makes up more than 70 percent of all the energy and matter in the universe and is pushing the universe apart at an ever-faster rate.
Another feature that distinguishes the new formulation is that it makes a testable prediction regarding the expansion rate of the universe. In addition, the micro-explosions created by the largest particle colliders should excite the dark energy field and these excitations could appear as exotic, never-seen-before sub-atomic particles.
"One of the things that is very unsatisfying about many of the existing explanations for dark energy is that they are difficult to test," says Scherrer, "We designed a model that can interact with normal matter and so has observable consequences."
The model associates dark energy with something called vacuum energy. Like a number of existing theories, it proposes that space itself is the source of the repulsive energy that is pushing the universe apart. For many years, scientists thought that the energy of empty space averaged zero. But the discovery of quantum mechanics changed this view. According to quantum theory, empty space is filled with pairs of "virtual" particles that spontaneously pop into and out of existence too quickly to be detected.
This sub-atomic activity is a logical source for dark energy because both are spread uniformly throughout space. This distribution is consistent with evidence that the average density of dark energy has remained constant as the universe has expanded. This characteristic is in direct contrast to ordinary matter and energy, which become increasingly dilute as the universe inflates.
The theory is one of those that attribute dark energy to an entirely new field dubbed quintessence. Quintessence is comparable to other basic fields like gravity and electromagnetism, but has some unique properties. For one thing, it is the same strength throughout the universe. Another important feature is that it acts like an antigravity agent, causing objects to move away from each other instead of pulling them together like gravity.
In its simplest form, the strength of the quintessence field remains constant through time. In this case it plays the role of the cosmological constant, a term that Albert Einstein added to the theory of general relativity to keep the universe from contracting under the force of gravity. When evidence that the universe is expanding came in, Einstein dropped the term since an expanding universe is a solution to the equations of general relativity. Then, in the late 90's, studies of supernovae (spectacular stellar explosions so powerful that they can briefly outshine entire galaxies consisting of millions of stars) indicated that the universe is not just expanding but also that the rate of expansion is speeding up instead of slowing down as scientists had expected.
That threw cosmologists for a loop since they thought gravity was the only long-range force acting between astronomical objects. So they had no idea what could possibly be pushing everything apart. The simplest way to account for this bizarre phenomenon was to bring back Einstein's cosmological constant with its antigravity properties. Unfortunately, this explanation suffers from some severe drawbacks so physicists have been actively searching for other antigravity agents.
These antigravity agents (dubbed "dark energy models" in the technical literature) usually invoke quintessence or even more exotic fields. Because none of these fields have been detected in nature; however, their proponents generally assume that they do not interact significantly with ordinary matter and radiation.
One of the consequences of allowing quintessence to interact with ordinary matter is the likelihood that the field went through a phase transition – froze out – when the universe cooled down to a temperature that it reached 2.2 billion years after the Big Bang. As a result, the energy density of the quintessence field would have remained at a relatively high level until the phase transition when it abruptly dropped to a significantly lower level where it has remained ever since.
This transition would have released a fraction of the dark energy held in the field in the form of dark radiation. According to the model, this dark radiation is much different than light, radio waves, microwaves and other types of ordinary radiation: It is completely undetectable by any instrument known to man. However, nature provides a detection method. According to Einstein's theory of general relativity, gravity is produced by the distribution of energy and momentum. So the changes in net energy and momentum caused by the sudden introduction of dark radiation should have affected the gravitational field of the universe in a way that has slowed its expansion in a characteristic fashion.
In the next 10 years or so, the large astronomical surveys that are just starting up to plot the expansion of the universe by measuring the brightness of the most distant supernovas should be able to detect the slowdown in the expansion rate that the model predicts. At the same time, new particle accelerators, like the Large Hadron Collider nearing operation in Switzerland, can produce energies theoretically large enough to excite the quintessence field and these excitations could appear as new exotic particles, the researchers say.
###
The research was funded by grants from the U.S. Department of Energy.
[Note: A multimedia version of this story is available on Exploration, Vanderbilt's online research magazine, at http://www.vanderbilt.edu/exploration/stories/darkradiation.html]
Ice Nine! (Cat’s Cradle, Kurt Vonnegut).
Snowball Earth ping!
Does Al Gore know about this? This quintessence field could explain why everything close to him keeps getting further away.
Interesting....
So what happens with this theory if the “red shift” is not really evidence of the Universe’s expansion....?
An interesting but corellating concept deals with the decrease in time itself. The reason we have stars farther away and older than the known Universe is that the concept we call time, the energetic medium that gives impetus to the next incremental Planck time, is dilluted, or crystalising. Good stuff.
What happens to the red shift. It would become an important aspect of most radiation reaching this planet, I would assume. Good question. The phase shifting concept is more sound than most. Definitely worth watching IMO. The crystalization, for lack of a better word, would decrease the available energy in the medium. Photons cannot, naturally, be slowed down around here. The medium drains them. We assume it means interaction with the space-time medium relative to movement. There is no agreement on the variability of time itself. I personally think that is the most important aspect to advance beyond the models we’ve got now. The snapshot. The promising thing about this line of thought is it deals with space as more of an object. Pretty cool stuff, nowhere near convinced, thanks for the reping.:)
The Doppler Effect has never been proven over large distances. The ‘red shift’ is the Doppler effect.
Black Hole Creates Spectacular Light Show (HST-1, enigmatic blob in the center of the M87 galaxy)
Hotter than the sun - Researchers directly observe Alfvén waves, which keep the corona sizzling
Giant solar waves spew more energy than 10 bn atom bombs
This thread at post #63...relates to the question of the "red shift" effect in understanding the age of the universe....
******************
See #17.
Seeing Red: Intrinsic redshifts, stable universe,/b>
*****************************EXCERPT INTRO************************************
Halton Arp's Seeing Red will completely change your cosmological views, even if you don't think you have cosmological views! Working entirely from observation, Arp sketches a picture of an eternal, infinite, stable universe which continually "unfolds from many points within itself."
Arp is an observational astronomer. He won his spurs as a graduate student in the 1950s measuring thousands of images of the stars in globular clusters, work which helped lead to derivations of the ages of those stars and thus of our Milky Way galaxy. He went on to compile "Arp's Atlas of Peculiar Galaxies," which became a classic. His familiarity with extragalactic objects, those beyond our Milky Way, is probably unmatched.
For about 30 years Arp's most important observations have been under academic ban; they contradict cosmological orthodoxy. That orthodoxy has denied observing time on the big telescopes to Arp and others who make discordant observations. It has excluded their most important discoveries from major journals. As far as the popular press is concerned, this small heroic band of observers just don't exist; their observations go unreported.
If you thought that the hard sciences are immune to philosophical irrationalism, you thought wrong. Today's academic science is as wedded to obsolete dogma as the church of Galileo's time, and is equally willing to ignore observation.
About 10 years ago Arp wrote his first book: Quasars, Redshifts and Controversies. He hoped that a comprehensive presentation of the evidence would lead professional astronomers to turn their instruments on the many objects which contradict current theory. Arp's immediate purpose failed; his book became a list of topics and objects that professional astronomers avoided at all cost. Like the bishops of Galileo's time, professional astronomers refused to look through the telescopes. This, of course, was a major scientific scandal and (of course!) it escaped the notice of the establishment press.
Still, Arp's first book was a success in a surprising way: it brought the suppressed observations to an audience of independent thinkers. Arp started getting letters from them: "from scientists in small colleges, in different disciplines, from amateurs, students and lay people." These were people who really looked at pictures, and who formed judgments on the evidence. Arp's first book brought them the evidence which then existed.
In the past 10 years, and despite academic opposition, the body of evidence has continued to grow. Arp's latest book, "Seeing Red" brings these developments to an even larger group of independent thinkers, some of whom will be the astronomers of tomorrow.
"Seeing Red" bears comparison with Galileo's "Starry Messenger." Just as Galileo's report of the phases of Venus and the moons of Jupiter demolished the geocentric theory of the universe, Arp reports observations that demolish the expanding universe/Big Bang theory. Just as Galileo's observations pointed to radically new physics, so do the observations from extragalactic astronomy.
Redshift
The key point at issue between orthodoxy and observation is the interpretation of redshift.
A cosmological phase transition -- similar to freezing -- is one of the distinctive aspects of this latest effort to account for dark energy -- the mysterious negative force that cosmologists now think makes up more than 70 percent of all the energy and matter in the universe and is pushing the universe apart at an ever-faster rate.AC/DC sez it best on their new album, track one, "Rock and Roll Train" -- but the chorus lyrics are "runaway train". Dark matter, dark energy, the same kludge, and not a good one.
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.
