archive-1: SETI Horizon - Fate of the Universe
SETI Horizon - Fate of the Universe
Larry Klaes ( lklaes@bbn.com )
Fri, 29 Jan 1999 10:51:04 -0500
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>Date: Thu, 28 Jan 1999 18:41:19 CST6CDT,3,-1,0,7200,10,-1,0,10800,3600
>X-OldDate: Fri, 29 Jan 1999 00:44:56 +0000
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>From: Paul Mundy <paul.mundy@mail1-gui.server.ntli.net>
>To: Carl Sagan List <carlsagan@craigerware.avalon.net>
>Subject: Sagan: Horizon - Fate of the Universe
>
>Someone was recently asking about the new interest in Einstein's
>cosmological constant. It was mentioned on TV here tonight.
>
>BBC's flagship science series Horizon returned for a new series tonight.
>This week's subject was cosmology, and the story of the search for a way to
>reveal the universe's eventual fate.
>
>Will the universe expand forever or contract to the Big Crunch? To find out,
>scientists need to know the rate at which the universe is slowing down, and
>to calculate this, they need to know the differing rates of slowing between
>nearby and faraway stars.
>
>The idea had been to use supernovae explosions to measure the distances from
>Earth. A supernova shines with the power of 10 billion stars, and each one
>shines with the same power and brightness for several weeks. However no
>astronomer had ever been able to devise a technique for discovering new
>supernovae, which, by their nature, are very rare and entirely
>unpredictable.
>
>Enter Lawrence Berkeley Labs physicist Saul Perlmutter. He figured that to
>work out the rate of slowing down of the universe he need to find 50
>supernovae. From 1987 to 1992 he worked on developing a wide angle camera
>with a CCD 10 times more powerful than previously available, and the
>necessary computer software to process the massive amounts of image data
>that would be produced.
>
>His technique is to photograph the same part of the sky three weeks apart,
>comparing the second with the first for new bright spots which could be
>supernovae. His technique worked, and now has been developed to the point
>where supernovae can be found almost on demand. Last summer the Horizon crew
>joined Perlmutter and his team at Keck Observatory in Hawaii, where they
>succeeded in discovering the most distant object ever viewed, a supernova 10
>billion light years away.
>
>Perlmutter now had data for 42 supernovae, enough to work out the rate of
>slowing of the universe. But the data turned up something totally unexpected
>- all the supernovae were 20% dimmer than expected, therefore they were much
>farther away than first realised. And after all the number crunching was
>carried out they discovered that the universe is speeding up, not slowing
>down.
>
>Some mysterious force is at work in the vacuum between galaxies, pushing
>against gravity and forcing galaxies apart. This is where the cosmological
>constant comes in. Einstein described it as the biggest blunder of his life
>but it has been resurrected to partly explain this new force.
>
>Eventually, all the galaxies will drift further and further apart, and the
>stars will burn out.
>
>One astronomer said that this discovery will be viewed as one of the most
>important of the 20thC.
>
>Once again, a marvelous Horizon documentary clearly explaining a fascinating
>subject.
>
>Horizon's web site is at http://www.bbc.co.uk/horizon/
>
>Cheers
>Paul Mundy
>(an inveterate Horizon fan)
>
>
>
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