Each time we get a new picture of one of the boys I put a 5x7 in a frame. I never take the old ones out, so each frame is almost like a photo album (except that you can usually only see the picture on top!). Today I was putting in Caleb's new picture, and I stopped to look at the oldest one I have in there; it was from when he was 4 years old. It really struck me how much the same yet how different he looks. He's definitely the same person and yet so changed.
I've written about this before, but time really intrigues me on all sorts of levels - pratical and mathematical. To go from age 4 to age 11, Caleb was changing every day, but we can't see any change from one day to the next, yet when we take a large number of days we CAN see tremendous change!
In physics, time is sometimes called a fourth dimension. In fact, as HG Wells puts it, scientific people "know very well that time is only a kind of space." One way to think of dimension mathematically is an independent direction in which we can move. We experience three spatial dimensions in which we can move pretty freely:
1) left/right 2) forward/backward 3) up/down.
Notice that we can go one direction and also the opposite of that direction, backward is the same dimension as forward, just in reverse. Any other movement is some combination of these; for instance, walking diagonally may be a combination of forward and left. We can move a shorter distance or a longer distance, can reverse direction and can move quickly or slowly or choose not to move at all in these dimensions. So, think of time as a dimension. We do move through it, but we are forced to go only one way and never to stop and always to go the same speed (one second per second).
If time is a dimension, shouldn't we be able to figure out how to move, by choice, at different speeds and in different directions through it? (Of course there are some problems posed when considering this.)