Universe offers 'eternal feast,' cosmologist says (Forwarded)

News Service
Stanford University
Stanford, California

Contact:
Dawn Levy, News Service
(650) 725-1944

Comment:
Andrei Linde, Physics
(650) 723-2687

February 9, 2007

Universe offers 'eternal feast,' cosmologist says
BY Kendall Madden

There is no such thing as a free lunch, some say, but they would be wrong.
In fact, the entirety of the universe defies them. According to Stanford
physics Professor Andrei Linde, one of the architects of the inflationary
theory, our universe (and all the matter in it) was born out of a vacuum.

"Recent developments in cosmology have irreversibly changed our
understanding of the structure and fate of our universe and of our own place
in it," says Linde, who will discuss the inflationary view of the universe
at the annual meeting of the American Association for the Advancement of
Science on Feb. 18 in San Francisco.

In the same session, titled "Multiverses, Dark Energy and Physics as an
Environmental Science," physics Professor Leonard Susskind of Stanford will
talk about string theory and its relation to inflationary theory and physics
Professor Lawrence Krauss of Case Western Reserve University will represent
the skeptic view.

The conventional theory of the Big Bang says that the newborn universe was
huge, containing more than 10**80 [ten raised to the power of eighty] tons
of matter. But physicists were stumped for an explanation of where all this
matter came from. Inflationary theory solves this problem by showing how our
universe could emerge from less than a milligram of matter, or perhaps even
from literally nothing.

From the Big Bang theory to inflation

Physicist Alan Guth of MIT proposed the inflationary theory in 1981, but its
original version did not work until Linde improved it. Guth and Linde
realized that rather than expanding at an ever-decreasing rate, as was
predicted by the Big Bang theory, the universe could have inflated at
exponentially rapid speeds.

Just as a landscape is diverse with peaks and valleys, quantum fluctuations
in the fabric of space-time form an energetic landscape. The energy driving
expansion of the universe, Linde explained, is a bit like a ball rolling
around a bowl. As the ball rolls down the side of the bowl, the intensity of
quantum fluctuations decreases until it reaches the stable point at the
bottom. The heat created by these oscillations at the bottom of the bowl is
what caused the Big Bang, and the preceding stage of inflation is what made
the bang so incredibly big, Linde said.

"Quantum events are taking place all around us," he said. "They are very,
very small." Some of these small quantum events caught up in the process of
rapid expansion of space became galaxies along the way.

"If galaxies are the result of quantum fluctuations," said Linde with a
shrug, "imagine what we are."

'An unexpected gift' from string theory

The possibility that enormously large galaxies originated from tiny quantum
fluctuations may seem too strange to be true. But many aspects of
inflationary theory were confirmed by recent astronomical observations, for
which the observers won the Nobel Prize in 2006. This gives some credence to
an even more surprising claim made by Linde: During inflation, quantum
fluctuations can produce not only galaxies, but also new parts of the
universe.

Take an expanding universe with its little pockets of heterogeneous quantum
events. At some point one of those random events may actually "escape" from
its parent universe, forming a new one, Linde said. To use the ball analogy,
if it experiences small perturbations as it rolls, it might at some point
roll over into the next valley, initiating a new inflationary process, he
said.

"The string theorists predict that there are perhaps 10**1,000 [ten raised
to the power of one thousand] different types of universes that can be
formed that way," Linde said. "I had known that there must be many different
kinds of universes with different physical properties, but this huge number
of different possibilities was an unexpected gift of string theory."

According to string theory, there are ten dimensions. We live aware of four
of them -- three of space plus one of time. The rest are so small that we
cannot experience them directly. In 2003, Stanford physicists Shamit Kachru,
Renata Kallosh and Andrei Linde, with their collaborator Sandip Trivedi from
India, discovered that these compacted dimensions want to expand, but that
the time it would take for them to do so is beyond human comprehension. When
a new universe buds off from its parent, the configuration of which
dimensions remain small and which grow large determines the physical laws of
that universe. In other words, an infinite number of worlds could exist with
10**1,000 different types of physical laws operating among them. Susskind
called this picture "the string theory landscape."

For many physicists, it is disturbing to think that the very laws and
properties that are the essence of our world might only hold true as long as
we remain in that world. "We always wanted to discover the theory of
everything that would explain the unique properties of our world, and now we
must adjust to the thought that many different worlds are possible," Linde
said. But he sees an advantage in what some others could see as a problem:
"We finally learned that the inflationary universe is not just a free lunch:
It is an eternal feast where all possible dishes are served."

[Kendall Madden is a science-writing intern with Stanford News Service.]

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Editor Note:

The symposium will take place Sunday, Feb. 18, from 3:30 p.m. to 5 p.m. at
the Hilton San Francisco, 333 O'Farrell St., San Francisco, CA 94102,
Ballroom Level, Franciscan C.

Science-writing intern Kendall Madden wrote this release. A photo of Linde
is available on the web at
http://newsphotos.stanford.edu/Linde.jpg (1.1MB)
[and Susskind at
http://newsphotos.stanford.edu/Linde_susskind.jpg (3.5MB)]

Relevant Web URLs:

* Andrei Linde's webpage
http://www.stanford.edu/dept/physics...de_andrei.html
* American Association for the Advancement of Science
http://www.aaas.org/