Big Bang, Big Crunch: Decrease in Entropy?

[Mark Nishimura]

In the 1990's two groups of astronomers, one led by Saul Perlmutter at
the Lawrence Berkeley National Laboratory, and the other led by Brian
Schmidt at the Australian National University, set out to determine by
measuring the recession speeds of type Ia supernovae.  After
painstakingly determining the distance and recessional velocities of
each, both groups came to a totally unexpected conclusion: ever since
the universe was about 7 billion years old, its expansion rate has not
been decelerating.  Instead, the expansion rate has been speeding up.
This observational data would coincide with Albert Einstein's 1917
introduction of the cosmological constant.  As ordinary matter spread
out and its gravitational pull diminished, the repulsive push of the
cosmological constant ( whose strength does not change as matter spreads
out) would have gradually gained the upper hand, and the era of
decelerated spatial expansion would have given way to a new era of
accelerated expansion.

About 100 billion years from now, all but the closest of galaxies will
be dragged away by the swelling space at faster-then-light speed and so
would be impossible for us to see, regardless of the power of telescopes
used.

See also works by Jim Peebles at Princeton, and also Lawrence Krauss of
Case Western and Michael Turner of the University of Chicago, and Gary
Steigman of Ohio State, all had suggested that the universe might have a
small nonzero cosmological constant.

Dark energy is the most widely accepted explanation for the observed
acceleration expansion, but other theories have been put forward.

-----Original Message-----
From: [hidden email] [mailto:[hidden email]] On
Behalf Of Carl
Sent: Wednesday, May 26, 2004 12:18 PM
To: The Friday Morning Applied Complexity Coffee Group
Subject: RE: [FRIAM] Big Bang, Big Crunch: Decrease in Entropy?


No.  Well, maybe.  Depends.
See http://www.math.ucr.edu/home/baez/open.questions.html
question #5.

Most of the recent stuff I read (granted, a small part and rather
opinionated portion of the total literature) says the expansion
appears to be speeding up, so I don't think this will be a worry.

carl

-----Original Message-----
From: [hidden email] [mailto:[hidden email]]On
Behalf Of Owen Densmore
Sent: Wednesday, May 26, 2004 10:31 AM
To: The Friday Morning Applied Complexity Coffee Group
Subject: [FRIAM] Big Bang, Big Crunch: Decrease in Entropy?


During a conversation yesterday with Stephen, it occurred to me that
the second law would be violated at the turning point to the big
crunch, right?

I.e. if the universe begins to shrink back to a singularity (well, not
quite if you think the string theory picture is right), wouldn't order
increase in that era?

        -- Owen

Owen Densmore         908 Camino Santander   Santa Fe, NM 87505
Cell: 505-570-0168    Home: 505-988-3787     http://backspaces.net


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============================================================
FRIAM Applied Complexity Group listserv
Meets Fridays 9AM @ Jane's Cafe
Lecture schedule, archives, unsubscribe, etc.: http://www.friam.org