Hiding in the Mirror

Hiding in the Mirror is by Lawrence M. Krauss, the author of The Physics of Star Trek. It is a narration of how extra dimensions have come and gone as theories of physics, and how they have stuck in the public's imagination.

Krauss describes how dimensions were treated in Flatland, written in 1884. The premise was a two dimensional being encountering a three dimensional being, and how that would relate to our meeting a being of four dimensions. He also talks about Alice in Wonderland and other books that explore multiple dimensions.

The author gives a good description of how various discoveries about light, electricity, and magnetism came together to form basic electromagnetic theory in the late nineteenth and early twentieth centuries. And then Einstein came along and produced his theories of special relativity and general relativity, concerning the nature of the speed of light, time, and the warping of time-space that we experience as gravity. I must admit that my scant knowledge in these areas was much improved after reading all this. I had thought I sort-of understood it, but Krauss's explanation was very good and thorough.

One thing that impressed me was his descriptions of theories and experiments being done in the twentieth century, and how often they validated each other. The existence of the positron was observed in 1932, but had been predicted by earlier theories.

Krauss gives a good description of how multiple dimensions came into theories as a way to explain various observations and unite theories of forces of the universe. At one point, twenty-six dimensions were posited. String theories today include up to ten or eleven dimensions. One recent discovery was that some of the ten dimensional theories can be expressed as variations of the eleven dimensional theory.

Eventually I get lost in all the theories. Relativity and quantum mechanics are just the beginning, and they have been well understood (at least by physicists) for nearly a century now. The various string theories and other theories build on them and get much more complicated.

The book is mercifully light on math. Honestly, I think I could have used a little more math to make sense of the concepts, but I don't for a second believe that any of the equations would be within my understanding, so he was probably wise to leave them out. Still, I was curious to see how some of the ten dimensional equations would work. One factor that intrigued me was the possibility of an extra curled up dimension that gravity works on. Since the force of gravity is reduced with the square of the distance between two objects, if gravity is propagated along an extra small dimension for short distances, then it could conceivably be very strong at extremely small scales.

The author touches again on multiple dimensions and alternate realities, but most of the last half of the book is descriptions of physics theories and experiments. The liberal arts major in me appreciates the cultural perspective, and the science part of my brain appreciates the complex physics. Overall it's a good mix, a well balanced meal, a B+.