Posted on 02/19/2002 9:19:22 AM PST by RightWhale
http://www.spaceref.com/news/viewpr.html?pid=7456
PRESS RELEASE
Date Released: Monday, February 18, 2002
American Association for the Advancement of Science
In search of extra dimensions: Hang on -- a new reality may be around the corner
BOSTON, MASS. -- "Reality is merely an illusion, albeit a persistent one," according to the late Albert Einstein. But, "if everything is an illusion and nothing exists," humorist Woody Allen has observed, "I definitely overpaid for my carpet."
Hang onto your carpet receipts:
Our understanding of reality -- that is, a world where events happen over time within a three-dimensional space -- may be turned on its head by the year 2005, scientist Maria Spiropulu said today during the American Association for the Advancement of Science (AAAS) Annual Meeting.
"The way we think about things is about to change completely," said Spiropulu. "This is truly a revolution in the way we understand our world."
Spiropulu, a 32-year-old scientist with the Enrico Fermi Institute at the University of Chicago, is hot on the trail of extra dimensions. She's using new methods to prove, experimentally, whether our reality is more complicated than we previously assumed.
"We are very close" to a new reality, she said. "Right now, we imagine space and time as a static question, and we solve equations as a function of space and time. But, what we're learning is that, at the very large scale or the very small scale, space and time are dynamic. What is happening at those scales, we cannot explain. So we have to wonder, do these scales hold some extra dimensions?"
Traditionally, physicists have mathematically explained all that happens in the world by using a "standard model." In this system, all matter is made of lightweight "leptons" (such as electrons and neutrinos) and quarks. Three forces manipulate these particles: electromagnetism, and strong and weak nuclear reactions.
But, this traditional approach doesn't explain gravity, the fourth force. The conventional rules of quantum mechanics have been successfully married with Einstein's Theory of Special Relativity, which explains the behavior of very fast objects -- but not with his Theory of General Relativity, the guidebook to gravitational force. Mathematical gobbledygook usually results from trying to combine quantum mechanics and general relativity. Consequently, we still don't know, for example, what happens to particles sucked into a black hole.
In an effort to uniformly explain all events, physicist Gunnar Nordstrom (1881-1923) first introduced the notion of an extra dimension at the beginning of the 20th century. Perhaps, he thought, gravity happens in a realm we don't understand and can't mathematically define. Some 10 years later, Theodor Kaluza (1885-1954) and Oskar Klein (1894-1977) took Nordstrom's ideas another step forward: An extra dimension may be curled up like an unimaginably small ball, they said, on the order of the Planck scale -- the smallest unit of length in the universe (10 to the minus 33 centimeters).
The idea of an extra dimension was resurrected yet again in the late 1990s, as scientists began to ask whether Newton's Law of Universal Gravitation reliably predicts gravity's behavior below the centimeter scale, Spiropulu explained. Physicists were energized in 1997 by the discovery of possible links between the standard model and "superstring theory" -- the notion that a series of extremely tiny, vibrating strings may lurk beneath the level of quarks and leptons.
Researchers Nima Arkani-Hamed, Savas Dimopoulos, and Gia Dvali then caused further excitement, by suggesting that at least one of these tiny dimensions might, in fact, be large enough to measure. Still, no one has produced undeniable proof of superstrings, and many questions persist.
Since then, Spiropulu reported to AAAS attendees, experiments have shown that Newton's Law is valid down to the 200-micron level. That is, gravity "follows the rules" at that scale. But, the physical reality below this level remains a mystery. Somewhere within the Planck scale, or at extreme energy levels, an incredibly small extra dimension may finally combine gravity and electromagnetism, Spiropulu suggested.
"We're very close into the energies where we can see effects of a very low-energy Planck scale," she said. "If an extra dimension is mirroring the Planck Scale, that means that gravity and the electromagnetic theory is going to be unified tomorrow."
Gravity, Spiropulu said, may soon be unified in an "unexplainable hierarchy of scale."
Various scenarios or "frameworks" are emerging to describe a mysterious sister world where, as Alice in Wonderland once remarked, "nothing would be what rings, because everything would be what it isn't."
Our three-dimensional world includes the coordinates X, Y, and Z, extending infinitely throughout the universe. But, some researchers have proposed that extra dimensions may be finite, and compacted around a sphere, pole, or other geometrical shape. Others have said that quarks, the standard-model particles, may have "technicolor" cousins in another realm. Or, quarks and neutrinos may exist in a mirror-world, as "squarks" and "sneutrinos."
To learn more about what's happening at the very small scale, Spiropulu and her colleagues are staging high-energy particle collisions. Extra dimensions, she explained, would leave behind a "signature," and she hopes to detect it. The classic signature might be a graviton -- the carrier of gravity -- capable, perhaps, of trickling to another dimension. In her experiments, protons (the hydrogen nucleus is a proton) going at almost the speed of light smash head-on into anti-protons. "What comes out," she said, "is a graviton, escaping into an extra dimension, and leaving a viable signature in your detector."
In particle collisions, the conservation of energy and momentum can be measured, so that what goes into the initial experiment must jive with what's left over, post crash-test. "If it doesn't add up and you have significant imbalance," she explained, "that is a viable signal that there is an extra dimension where, if these theories are valid, gravity may become very strong, and other weird properties might kick in. The idea is that there may be a form of super-gravity in the extra dimension."
Spiropulu shared the latest experimental findings at the AAAS meeting, including a completely new -- and what she described as "totally innovative strategy" -- worked out by Harvard's Nima Arkani-Hamed and others for "dynamically generating an extra dimension and then testing it," rather than the opposite, more conventional strategy: Searching for proof of an assumed extra dimension.
"We're looking at some really neat, new ideas," she concluded. "We hope by 2005 to have great results on this topic."
Is this just nuclear fusion in a beer can? Give me $1 billion and come back in 20 years?
This is Hindu/Buddahist dogma. It is also what I have observed. I think the only absolute truth is this: God or perhaps God is. Everything else is illusion.
Existence exists. Consciousness exists. You exist. A is A. A is not not-A.
I know him. We've both been involved with the American Linear Collider Working Group. He's a sharp guy, and a hell of a speaker.
What the article leaves out is the physics motivation behind large extra dimensions. The purpose is to solve what's known as the "hierarchy problem". Gravity, you see, is many orders of magnitude weaker than the other forces, which is one of the reasons why it's so hard to unify with the others. Let's suppose, however, that our 4-dimensional spacetime is but one slice of a higher-dimensional space, and suppose further that the strong, weak and electromagnetic forces were constrained to operate on that slice. If gravity alone were permitted to operate throughout the entire higher-dimensional space (often called the "bulk"), its effect as seen from the slice could be diluted to an arbitrary weakness, even though the actual strength of the interaction would be comparable to those of the other interactions.
One of the interesting consequences of Nima's theory is that electrons of different polarization would be displaced slightly from each other in the extra dimension. The displacement is energy-dependent, so two sufficiently high-energy polarized electron beams (as would be produced in a linear collider) could pass right through each other, missing each other, as it were, in the 5th dimension.
I pointed out to him once that this is almost exactly the physics behind the Oscillation Overthruster in The Adventures of Buckaroo Banzai Across the Eighth Dimension. He'd never heard of it.
Meanwhile, back here on the ranch, we gotta feed the chickens and milk the cows. Cows go mooo. Just so you know.
But, what about the red leptons?
The first "A" is at the start of the sentence, the second one is at the end.
So would each dimension have it's own displacement signature?
The Adventures of Buckaroo Banzai Across the Eighth Dimension.
Yep, that's definitely what comes to mind, monkey-boy!
My science fiction side wants to know that if these dimensions exist, and are extremely small, and exist outside of our space and time, if they could be entered and exited by something other than subatomic particles, could this be a way to move objects in our space without actually moving through our space and time?
It would seem to me that if you enter a parallel dimension, and subsequently leave it, you may not be where you started, in either space or time. If you were, that in itself would be unusual.
Here comes the headache....
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