by Bob Day
Copyright (C) June, 2012 by Bob Day. All rights reserved.
Time is weird. Maybe not as weird as consciousness, but definitely weird. But there are some simple things we can observe about time. First, it seems to be the property of our universe that provides the capacity for change. Without this capacity, things could not change. We see a car moving. "Now" it's at one spot. A little bit "later" it has moved a little farther down the road. Without time it couldn't do that — it would remain frozen in place. Question: Does time always involve motion? I think maybe it does. Suppose we're listening to music. The sound is changing. The sound is a sensation in our heads, and apparently not moving. But what causes the sound is atoms vibrating — moving back and forth — in the air. So sound requires motion to make it. I'm pretty sure it's all like that — same thing with a leaf changing colors: chemical reactions are involved, and, consequently, motion of atoms. Maybe you can think of a counterexample — an example of some kind of change that doesn't involve the motion of something.
Here's another weird thing about time: It seems to go at the same rate for everything. The definition of one second is this: "The second is the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom (at 0 degrees K)." OK, we have a stopwatch and we'll clock our cesium 133 atom. We time one second on our watch and count. Sure enough — 9,192,631,770 periods! Let's do it again. We get the same thing, 9,192,631,770 periods. So time went at the same rate in each of our measurements. But wait — that's our definition of time: whenever the cesium 133 atom makes 9,192,631,770 transitions, that's one second, no matter how long it takes. So our first measurement might have taken a second, and the second measurement, 100 years. Except that, if that were the case, our stopwatch (and everything else) would have had to slow down too. That's what I meant when I said that time, apparently, goes at the same rate for everything. And if that rate changes, it changes for everything at once.
So, as far as we can measure, time seems to flow at the same rate for everything, at least in our neck of the universe. But who is to say that time might not flow at a different rate in a chunk of space (in our same relativistic frame) a zillion or so light years away from us? The immediate consequence of that might be that the speed of light in that chunk of space would be different from our speed of light. Possible? I couldn't say either way. But, as far as I know, there is no rule that says the flow rate of time has to be a constant throughout the universe.