Quintessence, Accelerating The Universe?

When it doubt, go back to the basics. That is exactly what cosmologists have to explain why our universe seems to be accelerating.
The new buzzword in cosmology these days is "quintessence", borrowed from the ancient Greeks used the term to describe a mysterious "Fifth Element" - in addition to air, earth, fire and water - in the possession of the moon and stars in Place. Quintessence, some cosmologists say, is an exotic kind of energy field that pushes particles apart, overwhelming gravity and the other fundamental forces.

If quintessence is real, it would not be rare. Two-thirds of the universe would be the stuff. In the Texas Symposium on Relativistic Astrophysics in Austin, Paul Steinhardt of Princeton University, explained how the bottom line was dominant force in the universe a few billion years old, in a relatively short time, he says. Steinhardt not exactly warm on the set with his new theory.
Cosmology used to a quiet life. As recent as two years ago, most people were in agreement that, yes, the universe is expanding. In question was only whether the expansion would come slowly to a halt, and the universe falls back into itself, or whether the universe continue to float apart, but at a slower and slower. If there is enough matter in the universe, then gravity would halt the expansion and suck all know that we in the "big crunch". All cosmologists had to do was to add up the mass in the universe.

But in 1998, cosmologists were shaken from their seats by the discovery that the universe is expanding at an astonishing rate. New and Improved observations of distant supernovae have been rendering of the 'Big Crunch' question null and void.
Supernovae are stars explosions, and there are a few varieties. One, the so-called Type Ia supernovae, exploding with a characteristic energy. With a decent idea of the explosion and the absolute apparent brightness, astronomers determine the distance that these objects. Then know the redshift, they can calculate how fast the supernovae are away from us. If it is found that the most distant Type 1a supernovae have gone much faster then closer, suggesting that the universe's expansion is actually accelerating, not slowing down.
There are a few non-believers, with good reason. Some say that the most distant supernovae May only far (that is, dim), because the intervening dust dispersed its light. Also, we can not be sure that the most distant supernovae explode in the same way as closer.
Most cosmologists, however, have hopped on the train speeding universe. Their task now is to explain how they can be physically possible. Should not the force of gravity, the great attractor, hold the universe of Flying apart?

Einstein thought about, but for the wrong reason. He developed a Fudge factor called the cosmological constant. Einstein, and all others in the early 20th Century, thought the universe was static and that everything was within the Milky Way. The cosmological constant was an anti-gravity "vacuum" force to hold that gravity pulls from the universe. By 1930, Edwin Hubble discovered that the Milky Way was just one of a multitude of galaxies and that the universe is expanding. So there was no longer a need for a cosmological constant. Einstein, the number of his equations, he calls his "biggest mistake".

The problem with the cosmological constant, Steinhardt says, is that there is indeed constant. It provides the same force in the entire period. Observational evidence indicates that regardless of this force is that the acceleration of the universe, it was not constant over time. It had periods in which the power was negligible, because planets and stars and stripes squirrels never had.
"The cosmological constant is a very specific form of energy, a vacuum energy," Steinhardt said. "Quintessence covers a wide class of possibilities. It is a dynamic, temporally and spatially dependent developing form of energy with negative pressure sufficient to increase the pace of expansion."

Vacuum energy is the energy potential in an absolute vacuum, without the matter or radiation. Think of a chimney suck air from the living room, that's the universe of matter expanding into the great unknown. Quintessence is a quantum with both kinetic and potential energy. Depending on the relationship of both energy and the pressure they exert quintessence can either attract or repel.

Quintessence was to be expected, with around 10 billion years, according to the theory. That may be fairly early in a 15 billion years old universe, but cosmologist not see it. The dark energy was created when the universe 10-35 seconds old, they do not cause the universe to speed for another five billion years. That is a factor of more than 1050 - and in a relatively short time in terms of the redshift and the size of the universe.
Steinhardt quintessence indicates that during the transition from a radiation on matter-dominated universe when it cool enough for atoms and finally to form stars.
But what is quintessence? Nobody knows. Radiation, normal matter and dark matter probably all have positive pressure. They have therefore a gravitationally attractive force. Everything with negative pressure, the general theory of relativity dictates, would have a gravitationally repulsive force.

In essence, the quantum would have a very long wavelength of the size of the universe. His kinetic energy depends on the rate of vibrations in the field strength, its potential energy depends on the interaction of the field with matter. The more kinetic energy, the more positive pressure - that is not so likely to a universe long wavelength. So for the moment, potential energy and lower pressures. Therefore quintessence is a repulsive force.
This may change, says Steinhardt. Quintessence interaction with matter and evolves over time. Quintessence decay can also be used in new forms of hot matter or radiation. We are not necessarily doomed to a universe expands, that forever, which is every atom from here to infinity.

Sounds nice, but not everyone is sold.
"The theory of the universe is accelerating a work in progress," said James Peebles, professor emeritus at Princeton University. "I admire the architecture, but I do not want to move in just yet."

Namely, on the Texas Symposium, polite arguments over quintessence stretched well into the next interview. Some suggested that the nature of dark energy would become clear with a better understanding of gravity and gravitational waves. Steinhardt was admittedly at a loss with some of the questions. Astronomers and cosmologists are fascinated by quintessence, they simply need more information.

We will not be able to keep quintessence in our hands, nor can we probes to detect them directly. At best, we need tools, may find that the effect of the quintessence of the universe over time. Two space science missions are promising, said Steinhardt.

The Supernova Acceleration Project (SNAP) would systematically search for a large number of distant supernovae, beyond the reach of most space telescopes. Saul Perlmutter of Lawrence Berkeley National Laboratory, said, including in the Texas meeting, the efforts and described a not so complicated satellite with a two-metre telescope to search for supernovae at high redshift. SNAP would find about 2000 supernovae per year, enough to significantly close the error in bars calculations of the universe is expanding. The mission has not yet been funded.
Closer to the realization is Microwave Anisotropy Probe (MAP). It can detect small variations in the amount of quintessence of the sky as waves in the microwave background radiation remaining from when the universe was 300000 years old. Chuck Bennett, a MAP project manager at NASA Goddard Space Flight Center, is pretty excited.
"MAP is the best way to test quintessence in the immediate future," said Bennett. "Quintessence makes very specific predictions. To see if it is there or not is a non-brainer. To make a precise value, well, that's a bit more difficult."

At issue is how well the card can measure the quintessential factors in the equation, as the mass density of the universe, its geometry and the speed of expansion and the neutrino contribution.
Steinhardt certainly has a good track record. He was one of the originators of the theory of inflation and the acceleration predicts a universe in 1995. If quintessence has turned into something that scientists can sink their teeth into, it would be yet another confirmation of Einstein's theories, and a fine nod to the ancient Greeks, sent us this way.