----- Original Message ----- From: ""Hal Finney"" <[EMAIL PROTECTED]>
Sent: Saturday, May 07, 2005 2:48 PM
Subject: Re: Bitstrings, Ontological Status and Time
Time is just a coordinate, in relativity theory. The time coordinate has an opposite sign to the space coordinates, and that subtle difference is responsible for all of the enormous apparent difference between space and time.
I would agree that Time is just a coordinate (system), or as Leibniz claimed "an order of succession", if we are considering only events in space-time that we can specify, e.g. take as a posteriori. What I am trying to argue is that we can not do this in the a priori case for reasons that have to do with Heisenberg's Unceratanty Principle. Since it is impossible to construct a space-time hypersurface where each point has associated with it all of the physical variables that we need to compute the entire global manifold, from initial Big Bang singulary to the, possibly, infinite future, it is a mistake to think of time simply as a coordinate. OTOH, it is consistent if we are dealing with some particular situation and using Special (or General) Relativity theory to consider the behavious of clocks and rulers. ;-)
[HF] Granted, relativity theory is not a complete and accurate specification of the world in which we live (that requires QM to be incorporated), but it is still a self-consistent model which illustrates how time can be dealt with mathematically in a uniform way with space. Time and space are not fundamentally different in relativity; they shade into one another and can even change places entirely, if you cross the event horizon of a black hole.
I am trying to include the implications of QM in my thinking and hence my point about time and my polemics against the idea of "block" space-time. I do not care how eminent the person is that advocates the idea of Block space-time, they are simply and provably wrong.
In fact, one can construct models in which there are more than one dimension of time, just as we have more than one dimension of space. How would your renaissance philosphers deal with two dimensions of time? I think their ideas are obsolete and have no reference or value given our much deeper modern understanding of these issues.
If you look around in the journals and books you will find discussion of the implications of multiple-time dimensions. For example: