Tuesday, September 18, 2012

Brief Introduction to the physics of space, time, and motion.

In response to Anna:

Though it is uncomfortable to stand in as the voice of physics, I will make some observations. The good news is, space and time work (almost) exactly like you would expect because Bernard travels on a train moving at less than 1% the speed of light. Clock time, to say nothing of subjective time, passes for him (almost exactly) the same as somebody watching the train go by, and space for him is unchanged, though his perceptions of space, because he is human, are altered due to the landscape speeding past him. One thing I will quibble with is that physically, velocities are purely relative. Physicists would say something like "there is no preferred reference frame," but this simply means every observer is stationary from her/his perspective, and while Bernard on the train sees the farms moving by, and the farms see Bernard moving by, physicists believe both Bernard and the farms are correct. So in a rather profound way, when Bernard is on the train, he is still and the landscape is moving towards him. That is to say, there is nothing ontologically more subjective about viewing a landscape on a moving train rather than stationary relative to the landscape.

This isn't to say that this changes much in lived experience. Because we are humans, and can only imperfectly process the moving image, things certainly seem more streaky when on a train, and as you point out, we instinctively measure our motion relative to a landscape presumed to be stationary (but relative to what?); in human language, motion is presumed to be absolute, and there is a very visceral way in which we perceive ourselves as either moving or static, which we measure against terra firma, and this can engender psychological and emotional responses to the feeling of movement.

But, just thought it was worth noting that Bernard's experience on the train is no more subjective or somehow untrue compared with him standing in the fields. In fact, if that train were going at 25% the speed of light, if Bernard had sharp enough eyes and a fast enough brain to process things going by that quickly, time outside the train would pass about 3% more slowly than if he were stationary relative to the outside. And, this would be true. Because there is no fundamental difference between saying it is Bernard who is still, or the Earth which is still, physically speaking.

If what I said is unclear, as it seems to me to be, feel free to post questions.

3 comments:

  1. I'd like to have a more useful, informed comment, but for now let me simply say: is this liberal arts, or is this liberal arts?

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  2. Hey vincent, when thinking about why the book is titled what it is, did you ever think about how waves appear to be water moving from one location to another when in reality the water stays in one place - just rises and falls? Maybe this connects to Woolf's question about whether life is shifting or solid...?

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  3. From the wave's point of view, it remains stationary, and the ocean moves past it, and the beach approaches. Kind of similar to how we feel say death approaches us, but think of others as moving toward death. I think the waves definitely relate, right? They have paradoxical qualities of ephemerality (they last only a brief time before crashing and dissipating) and eternity (the ocean never ceases to produce waves). Perhaps they could be thought of as analogous to "being", because of their momentary nature (as they break) and their endless return, or to life.

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