The small differences in a person’s brain state that correlate with different bodily actions typically have negligible correlations with the past state of the universe, but they can be correlated with substantially different future evolutions. That’s why our best human-sized conception of the world treats the past and future so differently. We remember the past, and our choices affect the future.
I’m especially interested in the first sentence. It sounds highly plausible (if by “past state” we mean past macroscopic state), but can someone sketch the argument for me? Or give references?
For comparison, there are clear explanations available for why memory involves increasing entropy. I don’t need anything that formal, but just an informal explanation of why different choices don’t reliably correlate to different macroscopic events at lower-entropy (past) times.
It doesn’t seem to be universally true. For example, a thermostat’s action is correlated with past temperature. People are similar to thermostats in some ways, for example upon touching a hot stove you’ll quickly withdraw your hand. But we also differ from thermostats in other ways, because small amounts of noise in the brain (or complicated sensitive computations) can lead to large differences in actions. Maybe Carroll is talking about that?
Good point. But consider the nearest scenarios in which I don’t withdraw my hand. Maybe I’ve made a high-stakes bet that I can stand the pain for a certain period. The brain differences between that me, and the actual me, are pretty subtle from a macroscopic perspective, and they don’t change the hot stove, nor any other obvious macroscopic past fact. (Of course by CPT-symmetry they’ve got to change a whole slew of past microscopic facts, but never mind.) The bet could be written or oral, and against various bettors.
Let’s take a Pearl-style perspective on it. Given DO:Keep.hand.there, and keeping other present macroscopic facts fixed, what varies in the macroscopic past?
Sean Carroll writes in The Big Picture, p. 380:
I’m especially interested in the first sentence. It sounds highly plausible (if by “past state” we mean past macroscopic state), but can someone sketch the argument for me? Or give references?
For comparison, there are clear explanations available for why memory involves increasing entropy. I don’t need anything that formal, but just an informal explanation of why different choices don’t reliably correlate to different macroscopic events at lower-entropy (past) times.
It doesn’t seem to be universally true. For example, a thermostat’s action is correlated with past temperature. People are similar to thermostats in some ways, for example upon touching a hot stove you’ll quickly withdraw your hand. But we also differ from thermostats in other ways, because small amounts of noise in the brain (or complicated sensitive computations) can lead to large differences in actions. Maybe Carroll is talking about that?
Good point. But consider the nearest scenarios in which I don’t withdraw my hand. Maybe I’ve made a high-stakes bet that I can stand the pain for a certain period. The brain differences between that me, and the actual me, are pretty subtle from a macroscopic perspective, and they don’t change the hot stove, nor any other obvious macroscopic past fact. (Of course by CPT-symmetry they’ve got to change a whole slew of past microscopic facts, but never mind.) The bet could be written or oral, and against various bettors.
Let’s take a Pearl-style perspective on it. Given DO:Keep.hand.there, and keeping other present macroscopic facts fixed, what varies in the macroscopic past?