| And they are related to each other by
symmetry transformations. That's to say, they are all
equally good because the laws of physics are obeyed
whichever story you tell. In relativity, special
relativity, you get different stories according to what
inertial frame you take as your criterion of rest. Even
in classical physics you've got phase space. You can
choose different co-ordinates, instead of using position
momentum you can use position plus momentum and then
position minus momentum. So even there this notion that
there are different stories which are all equally good,
is beginning to come into focus. In quantum mechanics it
becomes crucial. So, it seems to me that what we really have to see is that the brain (is a physical system). Well first of all, there's a very useful notion that arises, even in classical physics, which I think hasn't really seeped into the imagination of most philosophers, let alone lay people, and this is a simple notion, it's the notion of a physical system. See, I think it's very natural to think, "well okay, if the mind is material, if the mind's really just a manifestation, then, presumably there is, perhaps, a bit of the brain where I live". I mean we were hearing about this, this morning, these intra-laminar nuclei and the thalamus, whatever. There's a bit of it, that is where I live, it is very natural to think. But first of all, one thing we know is we're only a bit of reality. I'm only a fragment of reality. My mind, if it's physical, is only a fragment of physical reality. And I think that it is very natural to think that the way you divide up reality is by a sort of spatial slicing, do you see? Well the point about the notion of a physical system is that it gives you a much more flexible way of slicing reality. What it really says is: take the brain, looked at from the point of view of the physicist, even the classical physicist now, really it's a system that is defined by a vast number of degrees of freedom. This is the notion that degrees of freedom are independent ways in which the system can change state or store energy. A point particle moving in space has three degrees of freedom corresponding to the three co-ordinates. That's a simple example. This notion of degrees of freedom... The thing is if you've got all these vast degrees of freedom, and any subset of those defines a perfectly good physical system in its own right, and it's a much more flexible way of producing a bit of a physical system. It's really that the notion of a physical system corresponds more to the notion of an aspect of something. But in a sense, this slicing by degrees of freedom is much more fundamental than the notion of slicing by saying the bit to the left and the bit to the right. It's just that we tend to think spatially because space is prominent in the way we visualise nature. But it seems to me that you're getting much more towards the essence of nature if you think of the way God, if we go back to him, that the way God would slice reality would be to slice it along the lines of degrees of freedom. So a part of reality is just a subset of the degrees of freedom of reality. That's much much more flexible. So that means that we shouldn't necessarily look for a part of the brain where the mind is. It might turn out to be that. But I think the neurophysiologists, neuroscientists are, to some extent, stuck in this very primitive idea of (spatial location). It may simply be that: if the idea is that my mind, my conscious mind, is a subset of the degrees of freedom of my brain, then it can be very spread out. Or it could be different aspects of lots of different bits which are playing a part, do you see? SJ: You've got this array of physical
subassemblies all doing their processing tasks SJ: They're producing output which is what I
equate with qualia. Now what you're saying, as I read it
at moment, is that those qualia actually have some kind
of physical existence. There is no way to make this a short story, I'm sorry. Let me bring this to some sort of conclusion. Okay, so you've got your physical system which we can think of in common sense terms, it represents an aspect of the brain. Then quantum mechanics tells us that there are an infinity of different ways in which you can tell the story about that system. The technical term is representations. And these representations actually correspond to different things you might want to measure or observe. In fact you know, when quantum mechanics was invented, there was a puzzle for a while, because there were two quantum mechanics, there was Heisenberg's quantum mechanics and there was Shroedinger's quantum mechanics. And they both seemed to work but they both looked incredibly different. And it was actually Schroedinger in the first instance who realised, in our modern language, that these were two representations. Heisenberg had an energy representation whereas Schroedinger had a position representation. And they were related to each other by a simple mathematical transformation. |