Why is Time One-Dimensional?

Differences between space and time have always been an interesting topic to explore, and none is more challenging than the dimensional differences. Space, it seems, can have any number of dimensions -- at least one of several, depending on the theory -- 1, 3, 9, 25 . . . . The point is, there doesn't seem to be a problem with space having more than one dimension.

Time, by contrast, almost always has a single dimension . . in any of the theories of spatial dimensionalities ranging, as above, from one to twenty-five, time always has that one, single dimension. As recently as last year, Bradford Skow, Philosopher of Science, from MIT, in an article published in the prestigious Nous, seems to back off from explaining time's one dimensionality, though he explains myriad other attributes of space and time. (Here's Dr. Skow's page at MIT http://web.mit.edu/bskow/www/.)

It seems to me the answer is straight-forward. Time can have any number of dimensions you like, but only one per universe. In other words, the big bang is a function of time. In the beginning there was an infinitesimal cosmic egg, that exploded and over time expanded into what we now call the universe. The point is, its explosive expansion was a function of time.

Think of the many worlds interpretation of quantum mechanics. The Schrodinger wave is also a function of time. When the wave collapses upon observation into a specific set of values, then each possible value corresponds to a different universe. Then, in each of those universes, the wave starts expanding again -- i.e., a function of time. That's why in the many-worlds interpretation, you've got the splitting of the wave into discrete universes. Since the wave is a function of time, and since each universe has a single time dimension, then any time another instance of the wave is created, it must be in a separate universe.

Anyway, there's a lot to be said on all this, and I'm trying to learn to keep my blog posts short. The point is this -- that a single time dimension is the distinguishing criterion for individuating universes. The only way you can say that two things are, not the same universe, but different ones -- is that their time-dimensions are distinct -- i.e., non-overlapping.

Here's another blogger's stab at the same topic:
http://allphilosophy.com/topic/4087

More to be said, especially as regards the so-called "principle of contradiction" -- which is provable from this (and other) properties of time!