There are two types of disciplined people: those who take consistent action through sheer willpower and those who do it without the use of willpower.
Ergodicity is one of the most important concepts to apply in life. However, few know about it, so here are three examples of how it is relevant for your career, sports, and social life. (My book on ergodicity contains more details).
But first, what is ergodicity? An activity is ergodic if the outcome of a single person performing it n times coincides with the outcome of n people performing it once. For example, in Russian Roulette, the expected outcome of many players playing it once is 5/6 (i.e., the survival rate) times the reward for playing it once. In contrast, the likely outcome for a single player playing it many times is death. Because the two outcomes differ, Russian Roulette is a non-ergodic activity.
This matters because, in non-ergodic contexts, permanent losses absorb future gains. For example, suppose you have $1000 and lose $600 in a market downturn. If the market doubles, you will only end up with $800. The $600 you lost cannot generate any more gains.
Let’s see a few more practical examples of how ergodicity applies to everyday life.
Racing
Suppose that a skier participating in a race has a two-in-ten chance of winning a race and a two-in-ten chance of breaking a leg. A championship has ten races. How many is he expected to win? (Of course, I exaggerated these chances, but for the sake of argument, let’s pretend they are real.)
A naive answer is 2. That is the chance of winning a race, two-in-ten, multiplied by the number of races, ten. This answer is wrong.
The skier can participate in the second race only if he survives the first; he can participate in the third race only if he didn’t break his leg in the first two, and so on. This means that he has an eight-in-ten chance of participating in the second race, and only an 80% * 20% = 16% chance of winning it. And a 80% * 80% * 20% = 12.8% chances of winning the third race, and so on. If you continue this calculation up to ten races, you discover that the skier is only expected to win 0.71 races, not 2.
In non-ergodic contexts, losses and game-overs (such as breaking the leg) absorb future gains.
Gym
For you to grow your muscles, you often need to push beyond what was your last limit. If you only lift the weights you’re comfortable lifting, your muscles will stop growing after the initial months.
On the other side, muscle gains only compound in the absence of major injuries. A small injury might result in a small setback, but a major injury might mean that you have to stop lifting or that your lifting potential is forever limited.
Training is non-ergodic: benefits compound only if survival is preserved.
Social relationships
The longer you are in a relationship, the better it gets. With a stranger, you can only talk about the weather or yesterday’s football match. As you meet a friend more times, the scope of what you can talk about and of the support you can give to and get from each other gets larger.
Social relationships compound: the longer, the more fulfilling.
If the relationship survives, that is.
Social relationships are non-ergodic: benefits compound only if survival is preserved.
Managing non-ergodicity
In life, it is of paramount importance to notice when you’re operating in a non-ergodic context and apply appropriate strategies. In my book “Ergodicity: Definition, Examples, And Implications, As Simple As Possible,” I describe three such strategies that you can apply to your life, career, organization, community, social life, and romantic life. You can find it here.
