Dear Chris,

A the risk of being a smart-alek, you answer your own question! The difference between Spatial and Temporal "dimensions" is that the former is such that movements can occur that are reversible without any involvement with any kind of "thermodynamic" laws. Temporal movements are strongly restricted by thermodynamics and causal restraints. Maybe we should be asking why this is the case!

As to the notion of more than one temporal dimension: we have that exact situation in the Many Worlds! Each path in the branching "tree" is a history, having its own notion of "time". The problem is that there does not exist a preferred basis with which to define such paths in an unambiguous way.

Kindest regards,


----- Original Message ----- From: "chris peck" <[EMAIL PROTECTED]>
Cc: <>
Sent: Monday, July 18, 2005 1:44 PM
Subject: Re: The Time Deniers and the idea of time as a "dimension"

But then, in what way is time asymmetric to space? You have no answer to that.

There may be operational reasons why time travel is or is not possible - I don't have any >>comments on the conjecture of time travel - my only stance being that I state it is and would be >>improper to consider Time as -not- being dimensional.

May I ask if you are as agnostic with regards to the possibility of walking north and then south as you are with regards to moving forward and backward in time? After all, space is a dimensional like time, isn’t it? If I claimed an ability walk in a circle, would you remain silent about that?

There are two ways in which time is not like space. I do not wake up to find myself travelling haplessly north, however I do wake up and find myself moving haplessly forward in time. Getting older and older by the plank instant. Secondly, I cannot reverse the flow of time. I can of course reverse freely my spatial vector.

Consider the manner in which relativistic theories freely interpret temporal direction. I’m thinking of Feynman diagrams interpreted as positrons moving forward or electrons moving back in time. Formally these interpretations are identical. To overcome the apparent absurdity of such a concept we dutifully imagine space-time as a (3+1) continuum. As Broglie explains:

"Everything for us that constitutes the past, present and the future is given en bloc. Each observer, as his time passes, discovers so to speak, new slices of space-time which appear to him as successive aspects of the material world, though in reality the ensemble of events constituting space-time exist prior to his knowledge of them."

It’s an ugly piece of writing, with obvious connotations of times within times not to mention a deeply deterministic conclusion. (I contrast 'deterministic' with 'indeterministic' here, rather than with 'free will').

I’m increasingly uncomfortable with such a picture. However - and this is the point I was trying to make last week - I do not think that one can account for temporal/spatial asymmetry by appealing to token reflexive statements. Contrary to McTaggart and Dummet, I do not think that a complete description of the universe can be given without spatial token reflexives ('here', 'there', 'this', 'that'). Dummet's contention that one can conceive of space without adopting a perspective must be one of the most contentious statements in contemporary Philosophy of Time. I can’t do it, and I suspect that Dummet cannot do it either. Consequently the obvious difference between temporal and spatial 'dimensions' is not captured. If one wants to escape the bloc universe view and entertain something more dynamic, I really think that such an approach falls flat.

No one must be more intuitive. What is true with regards to reflexives, as I’ve said in a different way, is that no contradiction follows from the statement 'what was there is now here', whilst paradoxes emerge from statements like 'what was past is now future'. Whilst it might be formally correct to allow for directions in time, it must be just conditional on an ideal rather than actual concept of time.

[c^2] is exactly an expression of the presence of 2 temporal dimensions orthogonally configured, >>computing against a sheet region not a linear one. [Rose(c)1995].

What then would it mean for two events to occur in temporally perpendicular directions?

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