Unnaturalness and Large Numbers

In the last chapter, we explored the power of naturalness. Dimensionless numbers that appear in physics, we said, are expected to be of order 1 numbers. That makes everything nicer and neater–and generally more tasteful. However, this prejudice does, at times, run contrary to the facts. There are some very big, as well as some very small, dimensionless numbers that crop up in physics. That issue, as we will see in this chapter, turns out to be a rather important aspect of modern physics. For explaining the presence, and persistence, of very large and very small numbers in nature constitutes one of the biggest challenges facing physicists today.