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No one actually has a working model of consciousness so that programme has a long way to go. But if the only evidence for time is change as Barbour likes to say

by meroes 5y ago

No one actually has a working model of consciousness so that programme has a long way to go. But if the only evidence for time is change as Barbour likes to say, and change basically boils down the relative motion of particles, why not describe the whole thing as a timeless table of coordinates essentially? And let psychologists build sensation and a perception of a flow of time from that. It's a tempting view due to its simplicity and the importance of math. But it is extreme, but so is every other theory or metaphysics trying to explain the same stuff!

fpoling 5y ago
This is a circular argument since motion is a change in position. So a change is a motion and a motion is a change. This implicitly refers to personal experience of perception of time flow, but nobody has figured out how to describe it with equations or model without references to that perception. It can be that this is even impossible since as with equations the words of language are static and can only refer to the perception of time without capacity to describe it.
- meroes 5y ago
  It is kind of circular - which suggests there is nothing unique about time. "The only evidence for time is change". Not "change (of particle position say) is one evidence of time passing". No - the ONLY evidence is change - the change in particle position for Barbour's simple examples. Therefore, do away with this extra baggage of time, and just look at particle positions. After all, we tell time (and motion) by the position of hands of a clock, the position or angle of stars, or the oscillation in position/momentum of atoms. What no one has done is understand consciousness or reduce biology to physics much at all. The math behind the above is extremely well known and ironed out. That is why some physicists now put the challenge on biologists and psychologists. The personal or subjective flow of time we all experience is theorized to be recreatable from this (timeless) framework. After all, all you have access to is a single snapshot and memories. Sensorial data and brain states. Registering and firing of nerves and neurons. Momenta of particles...why not? Just particle momementa in a table in some kind of sequential form (e.g. worldines in 4D spacetime block universe). I completely agree this may end up being an impossible challenge, or that it's later shown to be misguided. But there are accomplished philosophers and physicists behind it, or at least sympathetic to it.
  - fpoling 5y ago
    The problem is that there is no change or any notion of time flow in physical models. They describe a static 4-D universe. So there is no particle but there is a one-dimensional world line in the equations with no difference between points. Surely time has a particular property that is reflected in the equations that one can predict across time and not space. The notion of that world line reflects this. But this does not tell why we perceive those world lines point by point. I.e. a physical model is like a set of frames for a movie with particular relations between frames. But it does not tell why if we see the movie we perceive the motion and not, for example the whole movie at once. Or why the perception is across time and not space. And since these being discussed in various forms since at least Parmenides and Buddha I doubt this will be resolved any time soon.
    - tsimionescu 5y ago
      > The problem is that there is no change or any notion of time flow in physical models. What do you mean by this? When I write x(t) = x0 + (dx/dt) * t + (d2x/d2t) * t^2, time is right there in the equation. In relativity, it is even self-evidently different from the 3 spatial dimensions: s = sqrt(x^2 + y^2 + z^2 - (ct)^2). There is even a somewhat intuitive interpretation for the special-ness of the time dimension: all matter is constantly moving along the ct axis of space time at speed c, unless acted on by some force, trying to follow the shortest distance between the past and the future (so the trajectory bends towards the center of mass of any other matter it finds on the way).
      - fpoling 5y ago
        That equation describes a curve in 2 dimensional space with no differences between points with each point having particular time and space coordinates. And you can even resolve it to express time as a function of space. But we do not interpret that as a flow of space.
        tsimionescu 5y ago
        Sure, but you still can't explain it without adding an extra dimension to your model, and that extra dimension is not symmetrical with the space dimensions. In fact, there is no physical model that I am aware of that makes time and any space dimension interchangeable. The fact that our mathematical models generally seem to allow movement backwards and forwards in time is in stark opposition to observed physics. This obviously suggests that the models are wrong, and there is something about time we are not capturing well enough. Relativity does somewhat fix this, by essentially postulating that everything is moving with speed c in space-time, but that is a somewhat unsatisfying explanation, since it seems natural to ask why.

by meroes 5y ago

fpoling 5y ago

This is a circular argument since motion is a change in position. So a change is a motion and a motion is a change. This implicitly refers to personal experience of perception of time flow, but nobody has figured out how to describe it with equations or model without references to that perception. It can be that this is even impossible since as with equations the words of language are static and can only refer to the perception of time without capacity to describe it.

meroes 5y ago
It is kind of circular - which suggests there is nothing unique about time. "The only evidence for time is change". Not "change (of particle position say) is one evidence of time passing". No - the ONLY evidence is change - the change in particle position for Barbour's simple examples. Therefore, do away with this extra baggage of time, and just look at particle positions. After all, we tell time (and motion) by the position of hands of a clock, the position or angle of stars, or the oscillation in position/momentum of atoms. What no one has done is understand consciousness or reduce biology to physics much at all. The math behind the above is extremely well known and ironed out. That is why some physicists now put the challenge on biologists and psychologists. The personal or subjective flow of time we all experience is theorized to be recreatable from this (timeless) framework. After all, all you have access to is a single snapshot and memories. Sensorial data and brain states. Registering and firing of nerves and neurons. Momenta of particles...why not? Just particle momementa in a table in some kind of sequential form (e.g. worldines in 4D spacetime block universe). I completely agree this may end up being an impossible challenge, or that it's later shown to be misguided. But there are accomplished philosophers and physicists behind it, or at least sympathetic to it.
- fpoling 5y ago
  The problem is that there is no change or any notion of time flow in physical models. They describe a static 4-D universe. So there is no particle but there is a one-dimensional world line in the equations with no difference between points. Surely time has a particular property that is reflected in the equations that one can predict across time and not space. The notion of that world line reflects this. But this does not tell why we perceive those world lines point by point. I.e. a physical model is like a set of frames for a movie with particular relations between frames. But it does not tell why if we see the movie we perceive the motion and not, for example the whole movie at once. Or why the perception is across time and not space. And since these being discussed in various forms since at least Parmenides and Buddha I doubt this will be resolved any time soon.
  - tsimionescu 5y ago
    > The problem is that there is no change or any notion of time flow in physical models. What do you mean by this? When I write x(t) = x0 + (dx/dt) * t + (d2x/d2t) * t^2, time is right there in the equation. In relativity, it is even self-evidently different from the 3 spatial dimensions: s = sqrt(x^2 + y^2 + z^2 - (ct)^2). There is even a somewhat intuitive interpretation for the special-ness of the time dimension: all matter is constantly moving along the ct axis of space time at speed c, unless acted on by some force, trying to follow the shortest distance between the past and the future (so the trajectory bends towards the center of mass of any other matter it finds on the way).
    - fpoling 5y ago
      That equation describes a curve in 2 dimensional space with no differences between points with each point having particular time and space coordinates. And you can even resolve it to express time as a function of space. But we do not interpret that as a flow of space.
      - tsimionescu 5y ago
        Sure, but you still can't explain it without adding an extra dimension to your model, and that extra dimension is not symmetrical with the space dimensions. In fact, there is no physical model that I am aware of that makes time and any space dimension interchangeable. The fact that our mathematical models generally seem to allow movement backwards and forwards in time is in stark opposition to observed physics. This obviously suggests that the models are wrong, and there is something about time we are not capturing well enough. Relativity does somewhat fix this, by essentially postulating that everything is moving with speed c in space-time, but that is a somewhat unsatisfying explanation, since it seems natural to ask why.