'Cyclic universe' can explain cosmological constant

Charles D. Bohne wrote:

'Cyclic universe' can explain cosmological constant
19:00 04 May 2006
NewScientist.com news service
Zeeya Merali
http://www.newscientistspace.com/art...-constant.html


A cyclic universe, which bounces through a series of big bangs and "big
crunches", could solve the puzzle of our cosmological constant,
physicists suggest.

The cosmological constant represents the energy of empty space, and is
thought to be the most likely explanation for the observed speeding up
of the expansion of the universe. But its measured value is a googol (1
followed by 100 zeroes) times smaller than that predicted by particle
physics theories. It is a discrepancy that gives cosmologists a real
headache.

In the 1980s, physicists considered the possibility that an initially
large cosmological constant could decay down to the value measured
today. But this theory was abandoned when calculations showed that it
would take far longer than 14 billion years – the time since the big
bang – for the constant to reach the level seen today.

Now physicists Paul Steinhardt at Princeton University, in New Jersey,
US, and Neil Turok at Cambridge University in the UK, are resurrecting
the idea. They point out that if time stretches back beyond the big
bang, the problem could be solved. At that is just what is predicted by
their cyclic model of the universe – an alternative to the Standard Big
Bang theory – which the pair first developed in 2002 (see "Cycles of
creation").
Endless cycle

"Ever since the 1960s, people assumed that the big bang was the
beginning of time, because the laws of physics seem to break down
there," says Turok. But the equations of string theory tell a different
story, allowing time to exist before the big bang, he says.

According to Steinhardt and Turok, today's universe is part of an
endless cycle of big bangs and big crunches, with each cycle lasting
about a trillion years. At every big bang, the amount of matter and
radiation in the universe is reset, but the cosmological constant is
not. Instead, the cosmological constant gradually diminishes over many
cycles to the small value observed today.

The physicists' calculations show that the cosmological constant
decreases in steps, through a series of quantum transitions. Crucially,
the higher the value of the constant, the more rapid the transitions,
says Turok. But as the constant reaches lower levels, it changes more
slowly, lingering on the lowest positive value for an extremely long
time. That means that today's universe is most likely to have a small
cosmological constant, just as we currently observe, says Turok.

"This is an ingenious solution," says cosmologist Alexander Vilenkin at
Tufts University in Medford, Massachusetts, US. But he points out that
there are other cosmic coincidences that the cyclic model cannot
explain, like why the size of the cosmological constant is so similar to
the density of matter in the universe today.

Turok says that he and Steinhardt will be looking at that problem next.
"This is an initial attempt to go beyond Einstein's theory of gravity,"
says Turok. "It would be surprising if we solved everything first time."

Journal reference: Science (DOI: 10.1126/science.1126231)

nightbat

Thank you number one for your excellent report and yes they go
on and on trying to patch what they don't understand Rube Goldberg
style. Have you received any separate contact from the apparent fakeian
Seans yet? What a sad condition since bones left with promise of March
or April more contact.

Nothing coming comm. through and no positive word from Officer Greysky
either oh heaven help us for I sense trouble in Sean space paradise.

carry on,
the nightbat

Could you clear up what exactly is causing trouble for sean, frootbat?
Such powerful beings...

Saul Levy


On Sun, 07 May 2006 21:15:31 -0400, nightbat
wrote:

Thank you number one for your excellent report and yes they go
on and on trying to patch what they don't understand Rube Goldberg
style. Have you received any separate contact from the apparent fakeian
Seans yet? What a sad condition since bones left with promise of March
or April more contact.

Nothing coming comm. through and no positive word from Officer Greysky
either oh heaven help us for I sense trouble in Sean space paradise.

carry on,
the nightbat