Posted on 02/20/2004 3:14:03 PM PST by demlosers
WASHINGTON (Reuters) - Cosmologists had a bit of good news on Friday -- they are just about twice as certain as they were before that the Universe is not going to be ripped apart.
But if we really want to know what will happen, the United States must continue to care for the orbiting Hubble Space Telescope, or build a replacement soon, the researchers said.
The team at the Space Telescope Science Institute in Baltimore said they had found more evidence about a mysterious force called dark energy.
Discovered only six years ago, dark energy may make up 70 percent of the universe. It holds the key to the future of the universe, depending on how strong and how permanent it is.
Being Earthbound, the only way cosmologists can try to learn about it is through indirect observations. They use Hubble to look at the oldest, most distant supernovae they can find, and measure the light coming from them.
This light would have left the exploding stars billions of years ago and its color, known as red shift, tells astronomers about how fast they were accelerating at the time. This gives clues about the expansion of the universe and its age.
"In 1998 we first detected that the universe was accelerating and was apparently being driven to that state by this very mysterious dark energy that appears to make up 70 percent of the universe," the Institute's Adam Reiss told reporters. "That took us all by surprise. We don't really understand what it is."
NO MORE STARS IN THE SKY
One hope is that it is the explanation for Einstein's theoretical cosmological constant, a number that will predict whether the universe will collapse in a "big crunch," be completely blown apart in a "big rip" or just drift steadily until the galaxies are so far apart they cannot be seen -- in effect taking the stars from the sky.
"Right now we're about twice as confident than before that Einstein's cosmological constant is real, or at least dark energy does not appear to be changing fast enough (if at all) to cause an end to the universe anytime soon," Reiss added.
He and his colleagues will post a paper in the online version of the Astrophysical Journal explaining their findings.
"If Einstein was right and dark energy remains at the strength it is for all time, the Universe will expand forever," Reiss said. While this sounds more pleasant than a big crunch or a big rip, it also means a cold, dark and lonely future. Not that this will matter to humans, as it is an estimated 55 billion years off.
Still, it would be nice to know what is going to happen and the researchers have been dismayed to learn that with the space shuttle grounded, Hubble may be allowed to die.
It takes regular shuttle missions to maintain Hubble but after the shuttle Columbia broke up a year ago, killing the seven astronauts aboard, NASA has been forced to ground the other shuttles and rethink the program.
Reiss said the telescope, or a good replacement, is crucial for his team's work.
"We are pushing to very, very faint supernovae and we can't do this from the ground," he said. "I am hopeful that Hubble will last longer and I am hopeful we can continue to harvest these kind of data."
This is a reference to the time when the sun becomes a nova (note not supernova). This is when our solar system ends; not when the universe ends.
I feel more comfortable with a universe that has sufficient matter to collapse in on itself and go through a "big crunch". Perhaps from that we get another big bang and there is some hope of an eternity.
Hmmm... this is a very deep question. I will make an attempt.
So that men can analyze back-issues of Cosmopolitan Magazine to determine the point when women went wayward?
Fifty-Five billion years off........I suppose leftists of the future will be harping about how "Little Green Men Are Hit Hardest"
Doesn't sound like we get away to colonize other star systems, the end is nigh. ;-)
Is that a parrot-y or a parrot-dox?
Apparently our politicians think they will, because they vote to fund this research.
It'll be here before you know it.
<geek alert>
The one thing that is missing, however, is a mechanism by which to "quench" the expansion.
In inflationary cosmology, the expansion is driven by the existence of a large energy density throughout the vacuum, the existence of which causes gravity to be repulsive, rather than attractive. At some point, however, this "false vacuum" (being only weakly stable) decays down to the true ground state, and the inflation stops.
[Super geek alert: some work suggests that the false vacuum need not be an actual minimum in the vacuum potential. Even if there's only one minimum in the potential, if the vacuum state can get kicked into a high enough state (up onto the steep wall of a paraboloid, say), it can "surf" along for a while, held aloft by the expansion itself, before eventually sliding back down to the single energy minimum.]
In a "big rip", the dark energy density plays the role of the metastable "false vacuum", but there's no way to make it "decay" into free energy...at least, none we know of now.
I had thought of one possible mechanism to quench the expansion, but it won't work. My idea was to consider the vacuum energy density as being analogous to the ground state of the canonical one-dimensional particle-in-a-box, which appears in chapter 2 of every undergraduate quantum mechanics textbook ever written. The important feature is that as the sides of the box are moved farther apart--that is, as the box expands--the wavelength of the ground state gets longer, which is to say, it has a lower energy. Here's the key: if I double the size of the box, the first excited state has exactly the same energy as the former ground state. In other words, it's as if a new ground state has opened up beneath the old ground state, and the particle (in this case, the vacuum) has fallen into it. If this "decay" (by gradual surfing instead of catastrophic collapse, but that's OK) releases enough free energy, it will quench the expansion.
Unfortunately, this analogy is flawed, as Prof. Burt Ovrut pointed out to me. The essential feature of dark energy--or any vacuum energy--is that it is constant per unit volume. It doesn't "dilute" in this fashion as the universe expands, while the free energy does, and this is what enables the dark-energy-driven expansion inexorably to overcome the matter-driven deceleration.
Still, I haven't given up hope. There may be another method of quenching the rip that simply hasn't been thought of, yet. And if that's the case, the universe may, against all odds, be infinite and eternal, and entirely consistent with every detail of the Big Bang theory.
</geek alert>
Even though he is a total nutjob I am in complete agreement with Woody on this one...
"I don't want to achieve immortality through my work, I want to achieve immortality by not dying!" ---Woody Allen
Wouldn't that require the inflationary expansion to be a general feature of the universe? It was that way shortly after the Big Bang. But it doesn't now seem (to my limited knowledge) to be a local feature of our region -- only at the limits of what we can see.
Unless these observations worth both ways, and a hypothetical observer at the horizon sees us at his horizon, and he thinks our region of the universe is undergoing such an expansion. But if that's happening all around us, we seem oblivious to it.
</ignoramus mode>
It's all John Chichton's fault. I'll bet he spilled the beans to that half-breed Scorpius.
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