I understand from things like this that it doesn’t take a lot of (classical) uncertainty or a lot of time for a system to become unpredictable at scale, but for me that pushes the question down to annoying concrete follow-ups like:
My brain and arm muscles have thermal noise, but they must be somewhat resilient to noise, so how long does it take for noise at one scale (e.g. ATP in a given neuron) to be observable at another scale (e.g. which word I say, what thought I have, how my arm muscle moves)?
More generally, how effective are “noise control” mechanisms like reducing degrees of freedom? E.g. while I can imagine there’s enough chaos around a coin flip for quantum noise to affect thermal noise to affect macro outcomes, it’s not as obvious to me that that’s true for a spinner in a board game where the main (only?) relevant macro parameter affected by me is angular momentum of the spinner.
I think the quantum uncertainty can propagate to large scale relatively fast, like on the scale of minutes. If we take an identical copy of you (in an identical copy of the room, isolated from the rest of the universe), and five minutes later you flip a coin, the result will be random, as the quantum uncertainty has propagated through your neurons and muscle fibers.
(Not sure about this. I am not an expert, I just vaguely remember reading this somewhere.)
Usually we do not notice this, because for non-living things, such as rocks, a few atoms moved here or there does not matter on the large scale; on the other hand, living things have feedback and homeostatis, keeping them in some reasonable range. However, things like “flipping a coin” are designed to be sensitive to noise. The same is true for pinball.
I understand from things like this that it doesn’t take a lot of (classical) uncertainty or a lot of time for a system to become unpredictable at scale, but for me that pushes the question down to annoying concrete follow-ups like:
My brain and arm muscles have thermal noise, but they must be somewhat resilient to noise, so how long does it take for noise at one scale (e.g. ATP in a given neuron) to be observable at another scale (e.g. which word I say, what thought I have, how my arm muscle moves)?
More generally, how effective are “noise control” mechanisms like reducing degrees of freedom? E.g. while I can imagine there’s enough chaos around a coin flip for quantum noise to affect thermal noise to affect macro outcomes, it’s not as obvious to me that that’s true for a spinner in a board game where the main (only?) relevant macro parameter affected by me is angular momentum of the spinner.
I think the quantum uncertainty can propagate to large scale relatively fast, like on the scale of minutes. If we take an identical copy of you (in an identical copy of the room, isolated from the rest of the universe), and five minutes later you flip a coin, the result will be random, as the quantum uncertainty has propagated through your neurons and muscle fibers.
(Not sure about this. I am not an expert, I just vaguely remember reading this somewhere.)
Usually we do not notice this, because for non-living things, such as rocks, a few atoms moved here or there does not matter on the large scale; on the other hand, living things have feedback and homeostatis, keeping them in some reasonable range. However, things like “flipping a coin” are designed to be sensitive to noise. The same is true for pinball.