This is only indirectly relevant (e.g., are there cyclical big bangs that give
life, trans-universally, indefinitely many chances to evolve?), but I thought
people would find it interesting. I can access this story via
http://customnews.cnn.com/cnews/pna.show_story?p_art_id=1942544&p_section_na
me=Sci-Tech, but I don't know if this URL will work for everyone, and I
couldn't find the story (yet) on the regular Sci-Tech section of CNN's web
page.
--John
Excerpts from full article:
New Light on Fate of the Universe
Science
13-DEC-97
By James Glanz
In the flash of stellar explosions seen halfway back to the big bang, two
groups of astronomers have read clues to the future of the universe. With the
orbiting Hubble Space Telescope and ground-based observatories, they have
analyzed light from these remote cataclysms to estimate their distances and
determine how fast the stars were rushing away from Earth billions of years ago
when they exploded. Their goal is to learn how the universe's expansion rate
has changed over time--whether it has been slowed by gravity, or perhaps
boosted by large-scale repulsive forces. The groups, longtime rivals, have been
working independently, but their results agree: The universe's expansion rate
has slowed so little that gravity will never be able to stop it.
The new results imply that the universe contains far less mass than many
theorists had hoped: less than 80% of the amount that would be needed to slow
its expansion to a halt, and perhaps far less than that. The results even leave
open the possibility that a so-called cosmological constant--a hypothetical
property of empty space that might generate repulsive forces--is at work,
giving the universe an expansive antigravity boost. "The results are very
exciting and the method is very promising," says Neta Bahcall of Princeton
University.
....
If the results hold up as the groups add more supernovae to their samples, they
could have a major impact on how theorists picture the universe's first few
moments. Already, as word of these developments makes its way through the
astrophysics community, the findings are adding to a growing sense that the
simplest version of the reigning cosmic creation theory, known as inflation,
may not work. Inflation traces key features of the universe to a burst of
exponential growth in the first fraction of a second after the big bang, and
its simplest version predicts a universe that contains just enough matter for
gravity to stop the big-bang expansion after an infinite time--a mass density
that would make the large-scale geometry of space-time "flat."
....
Inflation can be modified to cope with a low-mass universe, says Andrei Linde,
a theorist at Stanford University who helped develop the theory. But "at some
point you can't patch a theory too much before it gets too ugly to accept,"
says Bolte of Santa Cruz. "That's what's going to come under fire, I think:
whether inflation is the correct model or not for the early universe."
With those debates still to come, along with plenty more supernovae, "it's
early times, my friend," says Princeton University's Jim Peebles. "You
shouldn't start paying off your bets."
Article Dated 12-DEC-97
COPYRIGHT 1997 American Association for the Advancement of Science
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