Brad said:
But isn't our intuition wrong--or perhaps it would be better to say that our intuition does not prepare us to study quantum mechanics and relativity? It's true that brains that have our intuitions of space and time tend to help the selfish genes that program them replicate themselves. But "fitness" is not the same thing as "truth"...
Indeed not. But, so far as I can tell, Dan isn't saying that we have intuitions about time that may or may not be correct, but that time *exists* because we have intuitions. I presume he means that something in our brain organises sense impressions into a spatial and temporal structure. I don't doubt that this occurs, but like you I think that this structuring only gives us an approximation to what's out there in nature. Furthermore, I think that it presupposes at least some kind of temporal structure (although perhaps I could be convinced that what looks like a temporal structure is in fact a constraint on spatial patterns in some kind of universe without time, or without temporal flow [as, indeed, the universes in some theories of quantum gravity might be, what with the vanishing of the Hamiltonian and all]).
Rich
I don't know what it means to say that time "flows" given the large number of events that have spacelike and not timelike separations. The fact that every electron-photon coupling looks "the same" in some sense (whether it is "an electron emits a photon and recoils," "an electron and a position meet and annihilate each other and their energy is transformed into photons," or "a photon breaks apart into an electron and a position") is mother nature telling us something. What mother nature is telling us is not clear to me, however...
--
Yours,
Brad DeLong
_______________________________________________ http://www.mccmedia.com/mailman/listinfo/brin-l
