The Mother of All Theories

At the end of the 1800s, the universe was neatly explained. The sciences of mechanics and electricity together successfully handled just about everything. However, the two theories were incompatible; they couldn't both be right. The end result, Einstein's discovery of relativity, blew apart modern physics and resulted in a scientific revolution.

By the end of the 1900s, science stood at a familiar point. The universe seemed almost entirely explained -- quantum physics and general relativity together successfully handled just about everything. But once again, the horizon is cloudy. Quantum physics and general relativity are incompatible; they can't both be right. Quantum physics can't explain gravity, and relativity can't explain the insides of an atom.

Scientists have been feverishly working to reconcile these differences. The most promising direction, which saw an impressive burst of progress in the 1990s, is called M Theory: the Mother of All Theories.

Actually, the "M" in "M Theory" might have started out as the Mother of All Theories, but since then scientists have also called it Magic, Mystery, Matrix and Membrane. (The last two refer to mathematical techniques used in the science.)

Why all this drama? M Theory has some startling conclusions which if proven will once again revolutionize modern science.

When scientists discovered that atomic particles were made of even smaller quantum particles like quarks and leptons, people naturally wondered if these too were made of something smaller. One possibility was string theory, which says that quarks and other particles are actually incredibly tiny vibrating strings, and that the type of particle seen is simply a different vibration of the strings, like different musical notes coming from the same instrument.

String theory was missing a lot of pieces however, and eventually it was developed into something called superstring theory which handled more of the puzzle. There were five different superstring theories and no way to tell which one (if any) were right.

Then, after delving into the depths of superstrings' obscure mathematics, scientists realized that the five theories might all be different ways of looking at a single theory: M Theory.

One startling consequence of M Theory is that our space-time is not four-dimensional after all. If M Theory is right, our universe actually has at least eleven dimensions.

The mathematics of M Theory requires that there are at least eleven dimensions in reality. The attraction of M Theory is that it can explain both gravity and the inside of an atom at the same time -- it solves the contradiction between current theories. With CERN's new high-energy collider, some of M Theory's predictions might be able to be tested for the first time in coming years.

Scientists are also trying to devise other experiments that could detect the existence of the other dimensions predicted by M Theory. Physicist Gregory Landsberg says that if the tests are successful, "This would be the most exciting thing since humanity discovered the Earth is not flat. It would give us a whole new reality to look at, a whole new universe."

A whole new universe -- or an unimaginable number of them. Just as many sheets of paper can be stacked on top of each other, many space-times like ours could be stacked next to each other in just five dimensions. Many of those stacks could be piled together in six dimensions ... and so on. The possibility of so many space-times is staggering. Our space-time, which we call the entire universe, could be just one tiny sheet of paper in an unimaginable mountain of similar sheets.

If there are more than four dimensions, why don't we see them? Scientists do not yet have an answer.

Science has a history of making our world bigger and our role in it smaller. First it was discovered that the sun and planets don't revolve around us; we revolve around the sun. Next it was discovered that the sun is not unique, but just an average star out of countless billions. Even our galaxy is just one of many. Now science may be on the cusp of discovering that our entire four-dimensional space-time continuum is just a tiny part of a eleven-dimensional whole.

What will this mean for our concept of reality, which is based on such a limited slice of the whole? Why don't we see the other dimensions? Is there anything in them? Is M Theory the first buds of spring of another scientific revolution?

Next: The Fall of Realism