Posted on 02/20/2004 10:26:32 PM PST by cinnathepoet
LOS ANGELES Feb. 20 — The mysterious "dark energy" that is pushing apart the universe appears to be the constant force that Albert Einstein once predicted, according to measurements made by the Hubble Space Telescope. NASA scientists announced their findings Friday, and details are to appear in an upcoming issue of Astrophysical Journal.The force is an unknown form of energy that behaves in an opposite manner from the pull of gravity. Dark energy causes the galaxies within the universe to move apart from one another at ever-increasing speeds.
Einstein called the force the "cosmological constant." He theorized its existence to balance the universe against normal gravity and keep it from collapsing on itself.
Einstein ultimately dismissed the theory as his greatest blunder, but subsequent observations of supernovas, or distant stars that exploded long ago, gave it credence. Scientists now know dark energy causes the universe to expand and accelerate. It makes up an estimated 70 percent of the universe.
What was unclear is whether dark energy is stable.
If it grows stronger with time, the universe could end with galaxies, stars, planets and, ultimately, atoms coming unglued in a violent expansion that theorists call the "big rip."
In the alternative, dark energy could fade away to the point where it flipped in force, pulling the universe back together in what's called the "big crunch."
The latest Hubble observations announced Friday suggest dark energy is unwavering, just as Einstein predicted.
"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," said Adam Riess, of the Space Telescope Science Institute in Baltimore, which looks at data sent from the Hubble.
Even if Einstein was wrong, dark energy won't spell an end to the universe for at least another 30 billion years, scientists said.
The latest results come from the measurements of multiple supernovas that exploded when the universe was half its present age of nearly 14 billion years.
The apparent brightness of a certain type of supernova allows scientists to gauge the expansion rate of the universe at different times in the past. That in turn allows them to measure any change in the strength of the force exerted by dark energy.
Further research is needed to prove dark energy is indeed a constant force, scientists said.
However, NASA's decision to no longer repair Hubble means the work will be interrupted until a replacement can be built and launched.
Ahhhh, finally we get to the crux of the matter; it's all Bush's fault. I mean, WHAT??? What are they doing putting that sentence in there? It has nothing to do with the article, except to transition into a cheap shot at Dubya. I hate the lamestream press. It's not worth reading.
Einstein ultimately dismissed the theory as his greatest blunder, but subsequent observations of supernovas, or distant stars that exploded long ago, gave it credence.
No expert on this, but as I learned it, what Einstein considered his greatest blunder was his assumption that the universe is static and his failure to consider the possibility that it was expanding (or contracting, for that matter). This article puts a slightly different spin on it--as though Einstein would now consider his abandoned "cosmological constant" theory vindicated. That seems unlikely to me, since the theory was only posited to explain his static-universe assumption, which remains unsupported.
More interesting is the unmentioned fact that this new data contradicts the Big Bang theory, which holds that the expansion of the universe began with a sudden burst and weakened over time. If the universe's expansion is growing stronger over time, it is hard to imagine it beginning with a bang.
(Phone: 202/358-1547)
Ray Villard
Space Telescope Science Institute, Baltimore
(Phone: 410/338-4514)
RELEASE: 04-067
NEW CLUES ABOUT THE NATURE OF DARK ENERGY: EINSTEIN MAY HAVE BEEN RIGHT AFTER ALL
The good news from NASA's Hubble Space Telescope is Einstein was right -- maybe.
A strange form of energy called "dark energy" is looking a little more like the repulsive force Einstein theorized in an attempt to balance the universe against its own gravity. Even if Einstein turns out to be wrong, the universe's dark energy probably won't destroy the universe any sooner than about 30 billion years from now, say Hubble researchers.
"Right now we're about twice as confident as 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," said Adam Riess of the Space Telescope Science Institute, Baltimore.
Riess used Hubble to find nature's own "weapons of mass destruction," very distant supernovae that exploded when the universe was less than half its current age. The apparent brightness of a certain
type of supernova gives cosmologists a way to measure the expansion rate of the universe at different times in the past.
Riess and other astronomers transformed Hubble into a supernova search engine, discovering 42 new supernovae, including six of the seven most distant known.
Cosmologists understand almost nothing about dark energy even though it appears to comprise about 70 percent of the universe. They are desperately seeking to uncover its two most fundamental properties: its strength and its permanence.
In a paper to be published in the Astrophysical Journal, Riess and his collaborators have made the first meaningful measurement of the second property, its permanence.
Currently, there are two leading interpretations for the dark energy, as well as many more exotic possibilities. It could be an energy percolating from empty space as Einstein's theorized "cosmological constant," an interpretation that predicts dark energy is unchanging and of a prescribed strength.
An alternative possibility is that dark energy is associated with a changing energy field dubbed "quintessence." This field would be causing the current acceleration -- a milder version of the inflationary episode from which the early universe emerged.
When astronomers first realized the universe was accelerating, the conventional wisdom was that it would expand forever. However, until we better understand the nature of dark energy -- its properties -- other scenarios for the fate of the universe are possible.
If the repulsion from dark energy is or becomes stronger than Einstein's prediction, the universe may be torn apart by a future "big rip," during which the universe expands so violently that first the galaxies, then the stars, then planets and finally atoms come unglued in a catastrophic end of time. Currently this idea is very speculative, but being pursued by theorists.
At the other extreme, a variable dark energy might fade away and then flip in force such that it pulls the universe together rather than pushing it apart. This would lead to a "big crunch" in which the universe ultimately implodes. "This looks like the least likely scenario at present," said Riess.
Understanding dark energy and determining the universe's ultimate fate will require further observations. Hubble and future space telescopes capable of looking more than halfway across the universe will be needed to achieve the necessary precision. The determination of the properties of dark energy has become the key goal of astronomy and physics today.
http://www.nasa.gov/home/hqnews/2004/feb/HQ_04067_dark_energy.html
NASA - New Clues About The Nature Of Dark Energy: Einstein May Have Been Right After All
That would have a certain symmetry to it -- the universe being created, running its course, then "evaporating." I wonder if the notion of "space" would continue in the big-rip scenario.
http://www.nasa.gov/home/hqnews/2004/feb/HQ_04067_dark_energy.html <-- Link
Being a church going guy I think what they talking about is the hand of GOD.
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