Numbers play a significant role in our daily lives, from calculating our daily commute time to understanding our mortgage payments. However, as a cosmologist, I am particularly fascinated by numbers that go beyond the mundane and have profound implications for understanding the universe. These numbers can be incredibly small or incomprehensibly large, but they all hold the potential to reveal the secrets of the cosmos and unravel the mysteries that continue to puzzle physicists today. Here are five astonishing quantities that are worth exploring:
10-120: Why is the vacuum energy so small?
Imagine shrinking a person to the size of a proton, and then repeating this process another eight times, each time reducing their size by the same ratio. The resulting miniature human would be 10-120 times smaller than their original size. To put this into perspective, this number is significantly smaller than the Planck length, which is a fundamental unit of distance at which space, as we understand it classically, ceases to make sense.
In nature, it is rare to find exponentially small or large ratios between sizes. When such ratios do occur, physicists are naturally driven to seek explanations. While there are no humans 10-120 times the size of a typical person, this minuscule number does emerge when comparing observations to the prevailing theory of the universe: quantum field theory. In particular, it becomes relevant when considering vacuum energy.
