By Joe Bauman
Deseret Morning News

      During the late 20th century, "much of the public considered physics kind of nutty," conceded Richard H. Price, University of Utah physics professor. "Now physicists consider physics kind of nutty."

Katrin Becker, an assistant physics professor at the University of Utah, is an expert on the string theory, which may help scientists predict the mass of an electron. Laura Seitz, Deseret Morning News

      Price's comments came last week when he introduced Gary T. Horowitz, professor of physics at the University of California, Santa Barbara. During his public lecture, Horowitz touched on many strange aspects of modern physics.
      But the most far-out idea — and the most revolutionary — is a yet-unproven notion called string theory.
      Other areas of physics that eventually proved true reached far beyond our "common-sense" notions of what the world is like, such as the fact that no matter what forces are involved, nothing can go faster than the speed of light.
      They are tame compared to string theory.
      Imagine a world of 10 dimensions.
      Or multiple universes co-existing with our own. These are among the most unusual aspects of the theory.
      It's such a burgeoning field of research that a weeklong conference on string theory and mathematics will be held at Snowbird Resort next June. Sponsors include the U.
      Based on Horowitz's talk and on telephone interviews with two string theorists at the U., here is a primer on string theory. The U. experts are Katrin Becker, assistant professor, and Yong-Shi Wu, professor, both in the department of physics.
      When we examine solid material on a small scale, Horowitz said, we find it is made of atoms that are mostly empty space. They are dense nuclei surrounded by clouds of electrons. The nuclei are made of protons and neutrons.
      These turn out to be made of smaller particles with different properties. They seem to be point-like, not sizeable chunks of material.

Yong-Shi Wu

      String theory holds that if we could enlarge the particles enough, we would find that they are actually not point-like but single-dimensional objects that are like "little loops of string," Horowitz said. The strings can vibrate in many ways. "The idea is that the different particles we can see correspond simply to different modes of vibration of these little strings."
      If a string vibrates one way, we perceive it as one kind of subatomic particle. If it vibrates in another style, it is a different type. Strings can interact by splitting into two loops, or two loops joining to form one.
      But it's not as simple as finding a different mechanism to explain particles.
      "The main prediction that string theory makes about space is that it must have more than three dimensions," Horowitz said. "In fact, string theory tells us that space has nine or even 10 dimensions."
      Where are these dimensions?
      "They're not just out in space someplace. They're everywhere, right here in this room," Horowitz said.
      "So why can't we see them? Well, one answer is that the theory's just wrong."
      But that answer is rejected by many physicists because string theory seems the most promising way to unite Einstein's theories of what happens on the large scale with quantum mechanics, the eerie actions that take place on the very small scale.
      If extra dimensions exist, they could be so tiny that nobody could see them with the equipment available now. They would be subsumed into our normal dimensions, as far as our perceptions are concerned — like looking at a row of microscopic dots and seeing a line.
      Recently, he said, another explanation has emerged. String theory also gives rise to "other extended objects" that may exist, called membranes, shortened by theorists to "branes."
      "There are three-dimensional branes which live in a higher-dimensional space," he said. We don't see the higher dimensions because we're embedded within our own three-dimensional brane. All the particles we are able to detect are "stuck on the brane," he said.

Gary T. Horowitz

      But other branes could exist, separated from ours. "And these might be viewed as parallel universes," Horowitz said. "This is, of course, very speculative," he added.
      Becker likens this era of research into string theory to the time when Einstein's theories had been postulated but not yet proven.
      "I think it certainly can be tested," she said. "The most important thing to me is to bring string theory to the point where we can make predictions."
      For example, with string theory it may be possible to predict the mass of an electron. If this matches what is measured experimentally, that would be an indication that string theory is correct.
      Also, a strange idea Einstein once had, then rejected — the cosmological constant — may be real after all. New research seems to indicate that the expansion of the universe, which has been going on since its start, is actually accelerating, and possibly string theory can tell why that is.
      String theory has opened exciting research, Becker said. "I think this is the last big adventure in physics."
      String theory, said Wu, has begun to bring physicists and mathematicians back together.
      If string theory ultimately is disproved, it will still leave behind a wonderful legacy, whole new areas of mathematics that are being developed. These "certainly will be left" as intellectual "jewels," Wu said.
      "When we see the beautiful mathematical results, this is for certain, at least," he said.
      What if it is proved true?
      Just as Einstein's theories were the foundation for nuclear power, string theory may open new realms.
      "Right now we cannot see anything definitely, OK?" Wu said. But if scientists can unlock the secrets of string theory, he said, "then who knows what can happen?"
     

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