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Kruno 01-03-03 10:44 AM

Something VERY intresting to put on the news page
 
'Dark energy' dominates the universe
HANOVER, NH - A Dartmouth researcher is building a case for a "dark energy"-dominated universe. Dark energy, the mysterious energy with unusual anti-gravitational properties, has been the subject of great debate among cosmologists.

Brian Chaboyer, Assistant Professor of Physics and Astronomy at Dartmouth, with his collaborator Lawrence Krauss, Professor of Physics and Astronomy at Case Western Reserve University, have reported their finding in the January 3, 2003, issue of Science. Combining their calculations of the ages of the oldest stars with measurements of the expansion rate and geometry of the universe lead them to conclude that dark energy dominates the energy density of the universe.

"This finding provides strong support for a universe which is dominated by a kind of energy we've never directly observed," says Chaboyer. "Observations of distant supernova have suggested for a few years that dark energy dominates the universe, and our finding provides independent evidence that the universe is dominated by this type of energy we do not understand."

The researchers came to this conclusion as they were refining their calculations for the age of globular clusters, which are groups of about 100,000 or more stars found in the outskirts of the Milky Way, our galaxy. Because this age (about 12 billion years old) is inconsistent with the expansion age for a flat universe (only about 9 billion years old), Krauss and Chaboyer came to the conclusion that the universe is expanding more quickly now than it did in the past.

The only explanation, according to Chaboyer and Krauss, for an accelerating universe is that the energy content of a vacuum is non-zero with a negative pressure, in other words, dark energy. This negative pressure of the vacuum grows in importance as the universe expands and causes the expansion to accelerate.

Source: http://www.eurekalert.org/bysubject/space.php

Could this mean the universe will never stop expanding?
What will that mean in the end I wonder?

saturnotaku 01-03-03 10:58 AM

I think it means that by the time anyting significant happens. every single one of us will be long dead. As they say easy come, easy go. :mohawk:

DaveW 01-03-03 11:42 AM

There is no conclusive proof yet, but this force has been theoretical for some time. Its well known that the universe is expanding, but it seems to be expanding at an increasing rate. Which suggests the existence of some force like gravity but working in the opposite manner. I hope this research leads to important practical applications like the hover-board in Back to the Future II :)

Mod 01-03-03 11:55 AM

Re: Something VERY intresting to put on the news page
 
Quote:

Originally posted by K.I.L.E.R

Could this mean the universe will never stop expanding?
What will that mean in the end I wonder?

Not really, there is a parameter lambda, in the FRW metric ( model that astronomere uses to describe the universe) which is influenced by the cosmological constant.

If it is 0<lambda<=1 , the universe there will be a positive pressure that makes the universe expand faster ( well, just if is no too dense, otherwise, even with the cosmological constant to make this positive pressure, there will be a bigger negative pressure cause by gravity that will make the univere to collapse).

If it is >1, it will (quite certainly) make the universe expand faster and faster until the light speed is achieved in a finite time. When it happens, the universe will end in a singularity ( it is not a punctual singularity, all the universe will become a 3D singularity, no time here, because time will be destroyed).

There is the case of l -1<lambda<0 in which the cosmological constant helps gravity collapse the universe and lambda <-1 , which I couldn't find in google :p .


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