The June 2008 issue of Scientific American sets out to answer a very perplexing question:

Why does time only move forward?

To find the answer, according to Sci-Am and Mr. Sean M. Carroll, we have to start looking at a very unlikely place:

To account for it, we have to delve into the prehistory of the universe, to a time before the big bang. Our universe may be part of a much larger multiverse, which as a whole is time-symmetric. Time may run backward in other universes.

The article is filled with high-end physics and a bit of science jargon, but Mr. Caroll puts uses neat little analogies to explain difficult concepts:

The asymmetry of time, the arrow that points from past to future, plays an unmistakable role in our everyday lives: it accounts for why we cannot turn an omelet into an egg, why ice cubes never spontaneously unmelt in a glass of water, and why we remember the past but not the future. And the origin of the asymmetry we experience can be traced…back to the orderliness of the universe near the big bang. Every time you break an egg, you are doing observational cosmology.

All in all, it’s a very interesting article and well worth a read. Some of the concepts used in the article are highly science fictional and are prime idea fodder for stories about multiverses and time travel. In fact, for those who’ve read River of Gods, may recognize the inspiration for ideas in that novel presented in this article. [image by gadl]