The Fabric of the Cosmos

Appearances Are Deceiving

Reality is not what we perceive it to be. That is the fundamental lesson of the past six centuries of scientific inquiry. The second lesson seems to be that we are far from knowing what reality is. Contemporary physics challenges almost all of our ordinary assumptions and intuitions about the nature of existence. For example, consider the idea that time moves forward - that the past is behind us and the future awaits. In fact, nothing in physics supports the notion that time moves at all. Equipped with the equations of physics, you would be hard-pressed to explain why whole eggs fall from kitchen counters and break, but shattered eggs do not reconstitute themselves on the floor and fall up to the counter.

The search for a unified theory occupied Albert Einstein for the last three decades of his life. Now that superstring theory may point the way toward such a discovery, our notions of reality may get another severe shaking. String theory suggests that the universe has many more dimensions than the four of which we are aware (three-dimensional spatial reality plus time). Superstring theory needs 11 dimensions: 10 dimensions of space and one...