Arthur Eddington was the greatest astronomer of his time in Great Britain, perhaps in the world, and made important discoveries linking Albert Einstein's theory of relativity with observed astrophysics. Eddington also attempted to compute the number of total protons and electrons in the the universe, and came up with an exact number, which is sometimes referred to as The Eddington Number.

But counting all the protons and electrons in the universe takes a bit of work, so I am going to talk about a different Eddington Number, the number that Eddington worked up in his leisure time, as a bicyclist. In this instance, the Eddington Number is the number of days that a cyclist has bicycled an amount of miles equal to that day. For example, someone who has on 30 separate occasions bicycled 30 (or more) miles would have an Eddington Number of 30.

The Eddington Number is significant because for a cyclist to raise their number, it often takes an exponential amount of work. For example, for the cyclist with an Eddington Number of 30, and has gained all of those by riding exactly 30 miles, none of them will count towards an Eddington number over 30. To get to 31, the cyclist must now undertake 31 new rides, of at least 31 miles. In cycling, then, while an Eddington number between 20 and 30 is common enough for weekend cyclists, the number rapidly tapers off after 30 or so. Eddington himself was still increasing his Eddington number in the high 70s just before his death at the age of 62.

Of course, the Eddington number can be applied to any other branch of human achievement that lends itself to clear quantification. In basketball, for example, we could talk about players with an Eddington number over 30--- players who have scored 30 or more points in a game, thirty times. And here as well, we would see the same pattern of tapering, for while many players have an Eddington number of 30, probably only a handful have an Eddington number of 40.

The Eddington Number is a rather simple way to measure achievement in an activity, that shows how hard it often is to go from good to great.