Sunbeams by Laurie Buchanan
One of the buzz words in the field of cosmology is “Quintessence.” And when it comes to it, I don’t pretend to be an expert, and neither do the experts…
In strict usage, cosmology refers to the study of the universe in its totality as it now is—or at least as it can be observed now—and by extension, humanity’s place in it.
The term quintessence was borrowed from the ancient Greeks who used it to describe the “fifth element.” In addition to earth, air, fire, and water, they believed that quintessence is what held the moon and stars in place.
A number of modern-day cosmologists say that quintessence is an exotic kind of energy field that pushes particles away from each other, overpowering gravity and the other fundamental forces.
In December of 2000 at the 20th Texas Symposium on Relativistic Astrophysics in Austin, Texas, Paul Steinhardt of Princeton University explained how quintessence became the dominating force in the universe.
In 1998 cosmologists were thrown off their proverbial rockers by the discovery that the universe is expanding at an astonishing rate. Since the discovery, their task has been to explain how this acceleration can be physically possible.
If it’s true, what does it mean for our planet—implosion, explosion? Or will the force of gravity, the great attractor, the mother of all forces, keep the universe from flying apart?
Einstein thought about this. He developed a fudge factor called the “cosmological constant.” Einstein, and many other intellects in the early 20th century, thought the universe was static and that everything was contained within the Milky Way galaxy. The cosmological constant was an anti-gravity ‘vacuum’ force that kept gravity from pulling the universe in on itself.
By 1930, Edwin Hubble discovered that the Milky Way was but one of a multitude of galaxies and that the universe was expanding. So, there was no longer a need for a cosmological constant. Einstein dropped the number from his equations, calling it his “greatest blunder.”
According to Paul Steinhardt of Princeton University, the problem with the cosmological constant is that it is, indeed, constant. It yields the same force throughout time. Observational evidence indicates that whatever this force is that’s accelerating the universe, it hasn’t been constant over time.
He said, “The cosmological constant is a very specific form of energy, a vacuum energy. Quintessence encompasses a wide class of possibilities. It is a dynamic, time-evolving, and spatially dependent form of energy with negative pressure sufficient to drive the accelerating expansion.”
Vacuum energy is the potential energy in an absolute vacuum, devoid of matter or radiation. Think of a chimney sucking air from the living room; that’s the universe’s matter expanding into the great unknown. Quintessence is a quantum field with both kinetic and potential energy. Depending on the ratio of the two energies and the pressure they exert, quintessence can either attract or repel.
Not everyone has jumped on the Quintessence Bandwagon. James Peebles, professor emeritus at Princeton University said, “The theory of the accelerating universe is a work in progress. I admire the architecture, but I would not want to move in just yet.”
At the Texas Symposium, there were a multitude of polite arguments over quintessence. Some suggested that the nature of dark energy would become clear with a better understanding of gravity and gravitational waves. Regardless, it’s evident that astronomers and cosmologists are intrigued by quintessence; they simply need more details.
One point that everyone agreed on was that two space science missions are promising:
The Supernova Acceleration Project (SNAP) and the Microwave Anisotropy Probe (MAP). If quintessence does prove to be something that scientists can sink their teeth into, it would be yet another confirmation of Einstein’s theories, as well as a fine nod to the ancient Greeks who sent us down this path.
What is your quintessence – what holds your personal world in place?
“Whatever you are not changing, you are choosing.”
– Laurie Buchanan
© 2010 Laurie Buchanan – All Rights Reserved
Tuesdays with Laurie 