Fwd: Scientists Dream of Parallel Worlds

[Richard Romeo]

somewhere over the rainbow...


>From: Stig Agermose <stig.agermose at post.cybercity.dk>
>
>Source: San Francisco Examiner,
>
>http://www.sfgate.com/cgi-bin/article.cgi?file=/examiner/hotnews/stories/24/co
>smos.dtl
>
>Stig
>
>**
>
>Scientists dream of parallel worlds
>
>By Keay Davidson
>
>EXAMINER SCIENCE WRITER
>
>July 24, 2000
>
>©2000 San Francisco Examiner
>
>*
>
>Alien universes might be stacked alongside ours like slices of
>ham and cheese in a Dagwood sandwich, according to a bizarre new
>scientific theory.
>
>This hypothesis is one possible implication of a radical concept
>of physics championed by scientists from UC-Berkeley, Stanford
>and New York University.
>
>Part of this concept holds that our universe might be shaped
>like a thin membrane - one slice of cheese, so to speak -
>surrounded by higher dimensions that transcend the three
>familiar dimensions of height, width and depth.
>
>According to the notion, six to seven dimensions exist beyond
>the three everyday dimensions, plus time. (Physicist Albert
>Einstein recognized time as the fourth dimension in 1905.)
>
>We live our lives confined to the surface of our
>three-dimensional membrane, oblivious to other dimensions, "much
>as the lives of (movie) actors unfold on a two-dimensional
>(movie) screen in a larger three-dimensional world," says
>UC-Berkeley physicist Nima Arkani-Hamed.
>
>He and associates Savas Dimopoulos and Georgi Dvali describe
>their "large extra dimensions" hypothesis and some of its wilder
>possible implications in the forthcoming August issue of
>Scientific American.
>
>Arkani-Hamed is an assistant professor of physics at UC-Berkeley
>and Lawrence Berkeley National Laboratory. He was born in
>Houston, but spent his early years in Iran, the child of two
>Iranian physicists. When he was 9, the family fled the ayatollah
>on horseback: "My family had huge political problems with the
>regime. We had no choice but to escape," he said.
>
>Dimopoulos, of Stanford, is a veteran physicist famed for his
>role in helping pioneer supersymmetry, an important modern
>paradigm of theoretical physics. (The new book "Supersymmetry"
>by Gordon Kane says the theory of supersymmetry "implies that
>each of the fundamental particles has a "superpartner' that can
>be detected at (particle beam) energies and intensities only now
>being achieved in the giant (particle) accelerators.")
>
>Dvali, at NYU, and Arkani-Hamed have reputations as bright young
>up-and-comers in the profession.
>
>In the past, other scientists, especially a camp of physicists
>called string theorists, posited the existence of six to seven
>extra dimensions. However, they assumed these extra dimensions
>would be extremely small - too small to detect with instruments
>called particle accelerators. Accelerators reveal the underlying
>nature of matter and energy by bashing together subatomic
>particles.
>
>The notion of other dimensions really isn't all that strange.
>
>For example, consider a pencil: If you see it from a great
>distance, it appears to be a straight line, that is, a
>one-dimensional object. Looking more closely, you can see that
>it has not only length but height - two dimensions. Seen even
>closer and from the side, the pencil displays a third dimension
>- depth.
>
>The assumption that extra dimensions exist is the latest blow to
>humans' old assumption of being important inhabitants of the
>cosmos, the three researchers say. That assumption was first
>shaken in the 16th century when astronomer Nicolaus Copernicus
>showed that Earth orbits the sun, not vice versa as
>traditionally thought.
>
>"The idea of extra dimensions in effect continues the Copernican
>tradition in understanding our place in the world," the three
>scientists write in Scientific American. "The Earth is not the
>center of the solar system; the sun is not the center of our
>galaxy. Our galaxy is just one of billions in a universe that
>has no center, and now our entire three-dimensional universe
>would be just a thin membrane in the full space of dimensions."
>
>If that doesn't send a chill down your spine, consider this: Our
>cosmos and alien universes might be like stacks of ham and
>cheese in a sandwich, each slice only a millimeter from the
>next.
>
>At this moment, you might be one millimeter - about fract,1,25
>1/25 inch - from, say, the frigid bottom of a dark ocean on an
>extraterrestrial planet, or the dusty chill of a cosmic dust
>cloud a million galaxies away, or the noisy interior of an alien
>bar packed with blue-skinned octopoids.
>
>You can't see these amazing sights. But - if the hypothesis is
>correct - they're there, literally next to you, forever veiled
>from view by your inability to perceive these dimensions.
>
>It sounds like a rejected script from an old "Twilight Zone"
>episode. Yet it's one reasonable - although far from proven -
>extrapolation from one of the hottest activities in physics, the
>effort to resolve an old conundrum: Why is gravity so much
>weaker than the other forces?
>
>That question might sound odd to nonphysicists. We're all
>accustomed to gravity's pull: It holds our feet firmly to the
>ground, plucks flowerpots off windowsills, drags hapless
>airplanes to their doom. Gravity also keeps the moon orbiting
>Earth, and Earth orbiting the sun.
>
>Yet to physicists, gravity is a wimp because it is extremely
>weak compared to the three other known physical forces -
>electromagnetism, the strong nuclear force and the weak
>interaction force.
>
>Electromagnetism gives us phenomena as diverse as light,
>electricity and magnetism. The strong nuclear force binds
>together the building blocks of atoms, namely protons and
>neutrons. The weak interaction force is responsible for
>radioactive decay.
>
>Consider a nail that lies on a table. It's held down by the
>gravitational force of the entire Earth, which weighs almost 6
>septillion tons.
>
>Yet Earth's grip on the nail can be instantly broken by a toy
>magnet that weighs just a few ounces. Just hold the magnet over
>the nail and - click! - the nail rises to meet it, courtesy of
>electromagnetic force. It's as if an ant could wrest an apple
>from Goliath's fist.
>
>Likewise, Arkani-Hamed and his colleagues point out, the
>electrical pull between two electrons (negatively charged
>subatomic particles) is
>10,000,000,000,000,000,000,000,000,000,000,000,000,000,000 times
>as much as the gravitational pull between them.
>
>"The feebleness of gravity is dramatic," they write in Scientific
>American.
>
>But why should it be? They propose that the reason is that the
>force of gravity, unlike the other forces, spreads through all
>dimensions, including the six or seven extra dimensions.
>
>Hence the gravitational force is immensely spread out, like a
>dollop of mayonnaise on a slice of bread. This makes it
>extremely weak on the "local" level, as compared with other
>forces.
>
>By contrast, the other forces are concentrated solely in the
>three-dimensional membrane in which we live. Being so
>concentrated, they're much stronger than gravity.
>
>  From there, it's a short step to the speculation that our
>membrane universe might repeatedly fold over on itself. The
>result: multiple universe slices adjacent to each other.
>
>Hence anyone at Point A in Universe One could be next to Point B
>in Universe Two, and next to Point C in Universe Three, yet
>they'd never be able to see or - as far as anyone knows -
>communicate with each other because light and the strong nuclear
>and weak interaction forces can't pass between universes.
>
>But gravity can. In that regard, Arkani-Hamed and his associates
>add, someday we might be able to detect the gravitational pull
>of giant masses, like stars, in other universes.
>
>Arkani-Hamed is "one of these guys who just has enormous fun
>thinking," says an admirer, the noted theoretical physicist
>Michael Peskin of Stanford Linear Accelerator Center in Palo
>Alto, where Arkani-Hamed once worked. "It was just extremely
>exciting to have him in the (physics) group here. Every day he
>would have some idea that would be amazing."
>
>Laboratory experiments are under way at Stanford University, the
>University of Washington at Seattle and the University of
>Colorado at Boulder to test the scientists' prediction that
>gravity would become much more intense at very small scales -
>say, over distances much less than a millimeter.
>
>One of the experimenters, physics Professor Eric Adelberger of
>Seattle, is using a laser to try to detect the changing
>gravitational force between an aluminum ring suspended by a
>tungsten thread and a rotating copper disk.
>
>Gravity is such a subtle force that it's a tremendously hard
>experiment to perform, Adelberger said. "Even the tiniest piece
>of dust in there will goof you up."
>
>*
>
>©2000 San Francisco Examiner

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