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It’s the definition from economics, not physics: https://www.nature.com/articles/s41567-019-0732-0#:~:text=It%20underlies%20the%20assumption%20that,essentially

It’s the definition from economics, not physics: https://www.nature.com/articles/s41567-019-0732-0#:~:text=It%20underlies%20the%20assumption%20that,essentially%20eliminated%20from%20the%20models https://www.nature.com/articles/s41567-019-0732-0#:~:text=It.... https://m.youtube.com/watch?v=f1vXAHGIpfc&feature=emb_logo https://m.youtube.com/watch?v=f1vXAHGIpfc&feature=emb_logo

pdonis 3y ago
> It’s the definition from economics, not physics They're pretty much the same, and have nothing to do with... "First, you have to understand a very important concept: in some systems, what’s best for a group is not necessarily what’s best for the individuals who make up the group. In other words, the total wealth of a group of people could be increasing, while almost everyone making up that group could be seeing their wealth diminish. When this happens, we say we have a non-ergodic system. If the system was ergodic, what’s happening to the collective would also translate to all individuals." ...which is how the article defines "ergodic" in the section with that name at the start.
- DVassallo 3y ago
  The author of that paper, an economics professor, agrees with my definition: https://twitter.com/ole_b_peters/status/1450761675049734144 https://twitter.com/ole_b_peters/status/1450761675049734144
  - pdonis 3y ago
    Argument from authority. Sorry, not buying it. The physics/economics definition is basically that time average = ensemble average. (The term "expectation value" is used in the Nature paper you reference, but that amounts to the same thing.) But individuals do not experience the ensemble average. A condition on averages is not the same as a condition on individual outcomes.
    - DVassallo 3y ago
      That’s how I used the term. YC experiences the ensemble average, while individuals are unable to realize their expected value because they only have one lifetime.
      - pdonis 3y ago
        > YC experiences the ensemble average Which could be equal to the time average, and thereby satisfy the definition of "ergodic" that was given, without in any way contradicting this: > while individuals are unable to realize their expected value because they only have one lifetime. I am not disputing that this happens. I am only disputing the use of the term "non-ergodic" to describe it, or the term "ergodic" to describe a hypothetical world where every individual experienced exactly the average outcome.

pdonis 3y ago

> It’s the definition from economics, not physics They're pretty much the same, and have nothing to do with... "First, you have to understand a very important concept: in some systems, what’s best for a group is not necessarily what’s best for the individuals who make up the group. In other words, the total wealth of a group of people could be increasing, while almost everyone making up that group could be seeing their wealth diminish. When this happens, we say we have a non-ergodic system. If the system was ergodic, what’s happening to the collective would also translate to all individuals." ...which is how the article defines "ergodic" in the section with that name at the start.

DVassallo 3y ago
The author of that paper, an economics professor, agrees with my definition: https://twitter.com/ole_b_peters/status/1450761675049734144 https://twitter.com/ole_b_peters/status/1450761675049734144
- pdonis 3y ago
  Argument from authority. Sorry, not buying it. The physics/economics definition is basically that time average = ensemble average. (The term "expectation value" is used in the Nature paper you reference, but that amounts to the same thing.) But individuals do not experience the ensemble average. A condition on averages is not the same as a condition on individual outcomes.
  - DVassallo 3y ago
    That’s how I used the term. YC experiences the ensemble average, while individuals are unable to realize their expected value because they only have one lifetime.
    - pdonis 3y ago
      > YC experiences the ensemble average Which could be equal to the time average, and thereby satisfy the definition of "ergodic" that was given, without in any way contradicting this: > while individuals are unable to realize their expected value because they only have one lifetime. I am not disputing that this happens. I am only disputing the use of the term "non-ergodic" to describe it, or the term "ergodic" to describe a hypothetical world where every individual experienced exactly the average outcome.