Re: Is Time Just an Idea?
Posted: January 16th, 2020, 6:45 am
Among the threads in the brief discussion between RJG and Terrapin Station, I am most interested in this thread:
This appears to me to be a thread about the idea of continuity across time and its relationship to the concepts we feel justified in reifying and the concepts we don't.
Terrapin Station's point, as I understand it, is that the concept of change doesn't automatically, logically imply the concept of what we might call "conservation of object". i.e. one object could (logically if not by empirical experience) simply be replaced by another. As he said, the thing that implies "conservation of object" would be some parameter of the system remaining constant from one temporal frame (as it were) to the next.
If I've understood this argument correctly, I agree. (I also agree that RJG's central error is to reify mathematical concepts like dimension. I think you can see why he does this by looking up his central thesis on this website - it's a form of Descartes' method of doubt.)
This is the essence of all principles in physics that can be described as "conservation laws". e.g. conservation of mass, energy, momentum, spin, charge, strangeness, charm etc. The thing that all of these conservation laws have in common is that they are expressions of the fact that in the mathematical equations describing the evolution of some physical system with respect to time, there is a term whose value does not change. When we spot a term like this, we are apt to reify the quantity represented by that variable and think of it as a "physical quantity". So, for example, we think of mass and energy like this.
Terrapin Station, I assume (from our previous discussion elsewhere) that you think we are right to reify these things? If so, are we right to reify any quantity that is represented by a term in an equation of physics that remains constant as the system evolves over time?
This is related to a topic I started on the specific example of mass (and its relationship to potential and kinetic energy), here:
viewtopic.php?p=345159#p345159
RJG wrote:Motion or change of WHAT? ...of a (non-real) "mathematical representation"??? ...or of a 'real' 3D object? -- "Motion/change" can't be real, unless there is something 'real' that moves/changes.
Terrapin Station wrote:There doesn't have to be some solitary thing that changes (from x into y). If we have an object that disappears and is replaced by a different object, then we have a change, but not a solitary thing that's changing.
RJG wrote:This is a logical self-contradiction. Is this "object" real? ...or not-real? ...you can't have it BOTH ways. It is logically impossible for the "change" of NOTHING (of non-real objects) to "occur". -- If NOTHING is changing, then there is NO CHANGING.
Terrapin Station wrote:You didn't seem to understand what I said.
The usual notion is that for there to be a change, there has to be something, x, that's a "unity" or "identity" that remains the same through the changes.
I explained that this is not the case. It's possible for there to be x, an object, which disappears and is replaced by y, a different object. That's a change--there was x, now there's y. But there's no single thing that remains the same during the course of the change. The object in question is real.
RJG wrote:Not so. -- In your example:
The object X "changed" states (from appearance to disappearance).
The object Y "changed" states (from disappearance to appearance).
It is logical nonsense to claim "change can occur" without some-'thing' changing. No-thing changing is no change.
Terrapin Station wrote:There's not an x that now has a state of having disappeared or being no longer existent. If x has disappeared or is no longer existent, there's no x to be in any state. What changed isn't x or y. What changed is that x existed but now y does instead.
This appears to me to be a thread about the idea of continuity across time and its relationship to the concepts we feel justified in reifying and the concepts we don't.
Terrapin Station's point, as I understand it, is that the concept of change doesn't automatically, logically imply the concept of what we might call "conservation of object". i.e. one object could (logically if not by empirical experience) simply be replaced by another. As he said, the thing that implies "conservation of object" would be some parameter of the system remaining constant from one temporal frame (as it were) to the next.
If I've understood this argument correctly, I agree. (I also agree that RJG's central error is to reify mathematical concepts like dimension. I think you can see why he does this by looking up his central thesis on this website - it's a form of Descartes' method of doubt.)
This is the essence of all principles in physics that can be described as "conservation laws". e.g. conservation of mass, energy, momentum, spin, charge, strangeness, charm etc. The thing that all of these conservation laws have in common is that they are expressions of the fact that in the mathematical equations describing the evolution of some physical system with respect to time, there is a term whose value does not change. When we spot a term like this, we are apt to reify the quantity represented by that variable and think of it as a "physical quantity". So, for example, we think of mass and energy like this.
Terrapin Station, I assume (from our previous discussion elsewhere) that you think we are right to reify these things? If so, are we right to reify any quantity that is represented by a term in an equation of physics that remains constant as the system evolves over time?
This is related to a topic I started on the specific example of mass (and its relationship to potential and kinetic energy), here:
viewtopic.php?p=345159#p345159