Friday, March 7, 2008

Physicism about time

Mathematical physicism (to coin a phrase) about time is the view that the only truth about the nature of time that is accessible to us is what mathematical physics teaches about time. Bergson, in Creative Evolution, gives what seems to me to be a pretty good argument against this view which I want to give in the following form: Consider the hypothesis that all events, whatever their t coordinate might be, are in fact simultaneous, and the t coordinate simply describes the location of the events along a fourth spatial dimension. This hypothesis is fully consistent with all of mathematical physics. Hence mathematical physics fails to tell us the nature of time, because it fails to distinguish time from space.

The argument does, however, presuppose that time is irreducibly different from space—otherwise the accusation that mathematical physics fails to distinguish time from space would be moot. Bergson does, of course, accept this assumption. I am sceptical of it myself.


Paul M. Rodriguez said...

Is this true? It is my sense that three dimensions of space and one of time are not mathematically equivalent to four dimensions of space. If I could move in a fourth space dimensions, I could turn right-handed gloves into left-handed ones--but I could not do that in the fourth time dimension, even with a time machine, because my movement would still always be locally unidirectional.

Alexander R Pruss said...

I think you could do it with a time-machine and spatial displacement, but only if the time-machine is able to send different portions of the glove to different times.

Paul M. Rodriguez said...

You could get a wearable glove that way (at least, it seems to work in Flatland.) But is it a topologically or algorithmically equivalent change? You would have to cut the glove, and you would have to decide where each piece should be put. I suspect that this operation is irreducibly more complex in time than it would be in higher space.