ANN ARBOR, Mich. - If you have
trouble understanding physics, maybe you should study Sanskrit.
It
wouldn't take long. You would just need to learn the Sanskrit symbol for
"om" (rhymes with home) and you'd be on your way to deciphering the secret
of the universe.
At least that's what some top physicists are
saying these days. The latest dish on the menu of hot physics topics is
something called OM theory, and physicists hope it will show them the way
to making everything in the universe one.
After all, that was
Einstein's goal - to find the math that would unify nature's forces in one
reasonably simple equation. He failed, but his successors continue the
quest. They seem confident that the new century will bring an even grander
success - equations that contain the essence of all the particles and
forces that the universe contains.
Most devotees of this agenda
believe that the path to this ultimate theory is paved with strings. More
concretely, these experts believe that particles of matter, and the
particles that transmit forces, are all just very tiny, one-dimensional
objects reminiscent of ordinary strings. People who like this idea call
them superstrings.
Superstrings take on different identities by
vibrating in different ways, the way a violin string sounds different
notes. But superstrings are much too small to play music; in fact, they're
vastly smaller than any known anything, notes Columbia University
physicist Brian Greene. Blow up a superstring to the size of a tree, he
says, and a nearby atom subject to the same expansion would become the
size of the visible universe.
A decade ago, superstrings seemed to
be the surest bet to provide physics with a theory of everything. They
seemed able to evade the toughest barrier to such a theory - merging
quantum physics with gravity. In fact, superstring theory required
gravity, providing a closed loop of string, kind of like a rubber band,
with just the properties needed to exert gravitational attraction.
Sure, there were some minor problems to solve. Superstrings needed
10 dimensions of space and time, and scientists (like everybody else) can
detect only four. And at least five different versions of superstring
theory seemed possible, with no clues to which one was the right one.
By the mid-1990s, though, progress had been made. The five
theories turned out to be just different views of one theoretical elephant
- known as M theory. In M theory, the one-dimensional rubber- band strings
add a dimension (or more) and become membranes, sort of like soap bubbles.
These "supermembranes" provide all the benefits of superstrings, at the
price of an additional dimension to worry about. (While superstrings need
10 spacetime dimensions, M theory requires 11.)
Alas, figuring out
just what M theory consists of has been too difficult for physicists so
far. After all, it is the mother of all theories.
"We've been
stuck with studying the whole thing all at once," says physicist Andy
Strominger of Harvard University. "And it's a lot to swallow."
But
just in recent weeks, physicists have discovered some bite- sized chunks
of M theory to chew on. Basically, the new ideas banish the closed,
rubber-bandlike strings from the theory, leaving only two- ended open
strings - or their higher-dimensional counterparts, open membranes.
The open membrane, or OM theory, is a lot simpler than standard
superstring/M theory. For one thing, there's no gravity to worry about.
But in other respects OM theory is very much like its more complicated
cousin. Working out the details of the simpler OM theory, Dr. Strominger
believes, could teach physicists the tricks they need to sink their teeth
into the entire M-theory enchilada.
"It's divide and conquer," he
said in an interview last week during Strings 2000, an international
physics conference held at the University of Michigan.
"String
theory itself is complex for many reasons," Dr. Strominger said. "So if
you can isolate some of the complexities and study them unhindered by the
other complexities, that's progress."
OM theory was introduced to
the physics world just last month, in a paper by Dr. Strominger, Nathan
Seiberg of the Institute for Advanced Study in Princeton, N.J., and
Harvard postdoctoral researchers Rajesh Gopakumar and Shiraz Minwalla.
Being from India, the postdocs quickly recognized that OM theory
is an especially appropriate name. As they note in their paper (on the
World Wide Web at xxx.lanl.gov/abs/hep-th/0006062), the meaning of om in
Sanskrit (as given by the Mandukya Upanishad) is "that which captures the
underlying nature of reality."
"It's not that it is the underlying
reality, it's that it captures the nature of the underlying reality," Dr.
Strominger said.
So even though gravity is excluded, studying
various versions of OM theory may very well point the way to the complete
unified theory, incorporating gravity with everything else, just the way
Einstein wanted.
"I think it's exciting," said Dr. Strominger.
"It's a new class of theories for us to try and understand that will, I
think, teach us a lot about the real theory, M theory."
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