A situation with given structure may matter to different degrees. The familiar special case is probability, when it’s uncertain whether the situation will occur. Depending on situation’s weight, you’d be willing to trade it for different alternatives, so this measure of situations is relevant for decision making. When a situation weights almost nothing compared to available alternatives, it’s irrelevant.
So in the case of quantum immortality or Boltzmann brains, the situations being discussed don’t matter compared to our world. They matter only for someone who happens to live in them and know it, to someone who can’t affect more. But why care for that guy of measure epsilon?
A single world admits many hypothetical situations, abstractions that express the features you care about. Knowledge of the world lets you judge their weight, decisions happen at the level of these abstractions, way above low-level description. So it doesn’t matter if the alternatives you are working with also in some sense correspond to things that are physically real. Even in a “many worlds” world, you’d be normally acting at a much coarser level.
See Preference For (Many) Future Worlds (it’s linked from Quantum immortality article on LW wiki).
A situation with given structure may matter to different degrees. The familiar special case is probability, when it’s uncertain whether the situation will occur. Depending on situation’s weight, you’d be willing to trade it for different alternatives, so this measure of situations is relevant for decision making. When a situation weights almost nothing compared to available alternatives, it’s irrelevant.
So in the case of quantum immortality or Boltzmann brains, the situations being discussed don’t matter compared to our world. They matter only for someone who happens to live in them and know it, to someone who can’t affect more. But why care for that guy of measure epsilon?
I’m acting under the Copenhagen interpretation, not many worlds. So I am talking about our world, not any other.
A single world admits many hypothetical situations, abstractions that express the features you care about. Knowledge of the world lets you judge their weight, decisions happen at the level of these abstractions, way above low-level description. So it doesn’t matter if the alternatives you are working with also in some sense correspond to things that are physically real. Even in a “many worlds” world, you’d be normally acting at a much coarser level.