Well, I’m not so much asking about the true nature of change or movement but rather just what we mean to say when we say that something is changing or has changed. I take it that if I told any layperson that a block of wood changed from dark to pale when left out in the sun, they would understand what I mean by ‘changed’. If interrogated as to the meaning of change they might say something like “well, it’s when something is in one condition at one time, and the same thing is in another condition at another time. That’s a change.”
But obviously that’s quite informal and ill suited to theoretical physics. On the other hand, physicists must have some basic idea of what a change or motion is. Yet I cannot think of anything more precise or firm than what I’ve said above.
If you go deep enough in physics, you don’t have “wood”. You just have a wavefunction. The wavefunction evolves with time in “classical” QM physics, and just exists statically in timeless physics.
And “the same thing” doesn’t mean much, since there is nothing like “this electron” but only “one electron”.
Saying that a piece of wood changed is an upper-level concept, which you can’t directly define in fundamental physics, but only approximates (like “pressure”, or “wood”, or “liquid”). The way you define your high level approximation doesn’t really need to know if the lower level is continuous or not. The same way you won’t define “liquid” differently just because we discovered that protons are not indivisible, but made of quarks.
Of course, lower level can be relevant : for example the fact there is no such thing as “this electron” contributes to saying that personal identity depends of configuration more than of “the same matter”. But it’s only a minor argument towards it, for me.
If you go deep enough in physics, you don’t have “wood”. You just have a wavefunction.
Fair enough, but surely the idea is to explain wood and the changes therein by reference to more fundamental physics. So even if the idea of change doesn’t show up at the very most fundamental levels, there must be some level at which change becomes a subject of physics. Otherwise, I don’t see how physics could profess to explain anything, since it would have nothing to do with empirical (and changable) phenomena.
Of course, lower level can be relevant : for example the fact there is no such thing as “this electron” contributes to saying that personal identity depends of configuration more than of “the same matter”. But it’s only a minor argument towards it, for me.
I’d love to talk more about that. Do you see configurations as platonic? And if our configuration is in constant flux (as is hard to doubt) on some level, do we therefore need to distinguish essential aspects of the configuration from accidental ones? And wouldn’t this view admit of two distinct persons having the same personal identity? That seems odd.
Well, I will say that a movie is “the same movie”, whatever it is stored on analog film, optical support, magnetic support or ssd storage. The content and the physical support are different issue. I’ll say that a movie “changed” if you cut or add some scene, or add subtitles, … but not if you copy the file from your magnetic hard disk to an USB key, even if there are much more differences at physical level between the HD and the USB key.
The same is true for personal identity, in my point of view. The personal identity is in the configuration of neurons, and even in the way changes propagate on the neural network, not in the specific matter distribution. Then, personal identity is not binary (am I the same I was one week ago ? and 20 years ago ?). But to a point yes, you can theoretically have two distinct “persons” with the “same” personal identity, if you can duplicate, or scan, a person.
Well, I’m not so much asking about the true nature of change or movement but rather just what we mean to say when we say that something is changing or has changed. I take it that if I told any layperson that a block of wood changed from dark to pale when left out in the sun, they would understand what I mean by ‘changed’. If interrogated as to the meaning of change they might say something like “well, it’s when something is in one condition at one time, and the same thing is in another condition at another time. That’s a change.”
But obviously that’s quite informal and ill suited to theoretical physics. On the other hand, physicists must have some basic idea of what a change or motion is. Yet I cannot think of anything more precise or firm than what I’ve said above.
If you go deep enough in physics, you don’t have “wood”. You just have a wavefunction. The wavefunction evolves with time in “classical” QM physics, and just exists statically in timeless physics.
And “the same thing” doesn’t mean much, since there is nothing like “this electron” but only “one electron”.
Saying that a piece of wood changed is an upper-level concept, which you can’t directly define in fundamental physics, but only approximates (like “pressure”, or “wood”, or “liquid”). The way you define your high level approximation doesn’t really need to know if the lower level is continuous or not. The same way you won’t define “liquid” differently just because we discovered that protons are not indivisible, but made of quarks.
Of course, lower level can be relevant : for example the fact there is no such thing as “this electron” contributes to saying that personal identity depends of configuration more than of “the same matter”. But it’s only a minor argument towards it, for me.
Fair enough, but surely the idea is to explain wood and the changes therein by reference to more fundamental physics. So even if the idea of change doesn’t show up at the very most fundamental levels, there must be some level at which change becomes a subject of physics. Otherwise, I don’t see how physics could profess to explain anything, since it would have nothing to do with empirical (and changable) phenomena.
I’d love to talk more about that. Do you see configurations as platonic? And if our configuration is in constant flux (as is hard to doubt) on some level, do we therefore need to distinguish essential aspects of the configuration from accidental ones? And wouldn’t this view admit of two distinct persons having the same personal identity? That seems odd.
Well, I will say that a movie is “the same movie”, whatever it is stored on analog film, optical support, magnetic support or ssd storage. The content and the physical support are different issue. I’ll say that a movie “changed” if you cut or add some scene, or add subtitles, … but not if you copy the file from your magnetic hard disk to an USB key, even if there are much more differences at physical level between the HD and the USB key.
The same is true for personal identity, in my point of view. The personal identity is in the configuration of neurons, and even in the way changes propagate on the neural network, not in the specific matter distribution. Then, personal identity is not binary (am I the same I was one week ago ? and 20 years ago ?). But to a point yes, you can theoretically have two distinct “persons” with the “same” personal identity, if you can duplicate, or scan, a person.