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Physicist Explains String Theory

From: UFO UpDates - Toronto <ufoupdates@virtuallystrange.net>
Date: Tue, 02 Dec 2003 09:56:33 -0500
Fwd Date: Tue, 02 Dec 2003 09:56:33 -0500
Subject: Physicist Explains String Theory 




Source: Daily Nexus - UC Santa Barbara's Student Newspaper

http://www.ucsbdailynexus.com/news/2003/6192.html

Physicist Explains String Theory to SB
By Ben Krasnow - Staff Writer

Monday, November 24, 2003


Physicist Brian Greene taught audience members how to see in 10
dimensions at the Lobero Theatre Sunday night.

A leading string theorist and a member of UCSB's Kavli Institute
for Theoretical Physics, Greene recounted the highlights of his
book, The Elegant Universe. After going over the physics
background necessary to understand string theory, Greene drew
audible "wows" from the audience when he explained the core
underpinnings of string theory, and how our understanding of the
universe could subsequently change.

Greene was introduced by Chris Carter, producer and writer of
the TV show, 'The X-Files'. Carter recalled reading Greene's
book and thinking about the implications of these new ideas in
physics. Sometimes the reality of what theoretical physics
predicts is hard to grasp, even for a science fiction writer.

"As strange as 'The X-Files' could be, we never got as far out
as this guy," Carter said.

Theoretical physics describes a branch of science that tries to
explain physical phenomena by using mathematics and careful
thought instead of empirical measurements. Greene hailed Albert
Einstein as the most influential theoretical physicist in
history.

"He changed the ideas of space and time," Greene said.

Einstein's first major contribution to the modern understanding
of physics was the introduction of the ultimate speed limit -
 the speed of light, Greene said. Before this maximum speed
limit was introduced, scientists thought some things could
happen instantaneously, like gravity. Newton's law of
gravitation states that the attraction felt between two objects
is instantaneous. Einstein stated that this is not possible.
Nothing - no signal, no information, no influence - can travel
faster than the speed of light.

Light has been measured to travel at 186,000 miles per second.
The sun is so far away that even at that tremendous speed, it
takes nearly eight minutes for the its light to reach the Earth.
If the sun disappeared right now, we could not possibly know
until eight minutes had passed. Earth's gravitational attraction
to the sun holds the planet in orbit. If gravity acted
instantaneously and light did not, the earth would leave its
orbit before the darkness accompanying the sun's disappearance
reached it.

"The fact that there is a speed limit is a problem for Newton's
Law," Greene said.

Greene said that Einstein's second major contribution was his
theory of general relativity. This theory provides a way to
understand how gravity works while still obeying the maximum
speed limit. In fact, Einstein's calculations proved that the
speed of gravity should be exactly the same as the speed of
light. Greene said the reason Einstein has been praised so much
is because his ideas unified two things - the speed of light and
the speed of gravity. Physical theories that unify separate
phenomena are always desirable because they approach the idea
that there is one singular theory that could explain everything
in the universe, Greene said.

To explain general relativity, Greene used the analogy of a thin
horizontal rubber sheet. If the sheet was perfectly flat, a
marble placed on the sheet would have no tendency to roll in any
direction. If a bowling ball was placed on the sheet, it would
form a large depression. The marble would roll down into the
depression, toward the bowling ball. The heavier the bowling
ball, the bigger the depression, and the faster the marble will
would roll toward it. If the bowling ball were removed very
quickly, the rubber sheet would take a short time to return to
its flat shape. That amount of time is analogous to the speed of
gravity.

"Gravity is the fabric of space and time," Greene said.
"Einstein's theory works just a little better than Newton's."

In the case of the sun disappearing, general relativity states
that the earth would remain in orbit for eight minutes after the
sun is gone. This is the time it would take for the gravity wave
to reach earth and release it from the depression in space that
is currently holding it the sun's orbit.

Besides relativity, there is another area of physics that has
changed markedly in the last century. This field is called
quantum theory, and it describes how physics works on a very
small scale. Greene said that on a macro scale, the warping of
space is very smooth, like a smooth depression in a rubber
sheet. On the micro scale, space is not smooth. It is constantly
churning and moving, like the surface of boiling water. Quantum
theory describes this rapid and chaotic motion, and has some
startling physical conclusions.

"If you fire a particle like an electron at a barrier that
classically it could not penetrate, quantum theory says there is
a small chance it can," Greene said.

Greene went on to say that there is even a chance that he could
walk into a solid stone column and come out on the other side.
The probability is extremely low, but it is not zero according
to quantum theory.

String theory provides a way to unify the smoothness of macro
space and the roughness and chaos of micro space, Greene said.
The basic concept of string theory is that every piece of matter
in the universe is composed of very small vibrating loops of
string. The pattern of vibrations, much like the pattern of
vibrations on the string of a musical instrument, determines the
properties of the particle it composes, Greene said.

The dilemma is that the mathematics behind string theory require
the tiny loops of string to vibrate in 10 dimensions. This is a
problem because no person has ever seen more than three
dimensions. This conclusion does not daunt string theorists like
Greene. He explained one way in which the other seven dimensions
could be hidden to observers by rolling up a sheet of paper. If
the flat plane of paper represented space, it has two
dimensions: top to bottom, and left to right. If the paper is
rolled up into a cylinder, the left to right [[left-to-right]]
dimension is unchanged, but the top to bottom [[top-to-bottom]]
dimension is changed into clockwise or counterclockwise. If the
paper is rolled tighter, the cylinder will be come very thin,
and from afar it may look like a simple line with no rolled-up
clockwise dimension. This may be how the seven other dimensions
of string theory are hidden.

Greene said that string theory could be strengthened by
observational data from space. When the universe was young, the
strings that made up all matter were very energetic. As the
universe cooled down and expanded, the imprint left from the
energetic strings may have remained. Thus, there could be large,
string-shaped artifacts in space waiting be found that would
provide evidence for string theory.

"Nothing to me would be more poetic; no outcome would be more
graceful ... than for us to confirm our theories of the
ultramicroscopic makeup of spacetimea and matter by turning our
giant telescopes skyward and gazing at the stars," Greene said.


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