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Is this a correct was to view Space-Time?
Today, I saw a school bus coming toward me. At every moment, we were drawing closer. It occurred to me that if I could follow the "past moments" of that bus, I could trace it's route all the way back to where it started. At every gazillioneth of a moment, that bus was somehow just a bit different than it was a gazillionth of a moment before. It was in different space. I was seeing CLEARLY only the most current moment of it's existence. If I could have seen the last, say, 10 minutes AT ONCE, I would have seen a long yellow streak (I suppose) that would go all the way back to wherever it was 10 minutes before.
AM I UNDERSTANDING THIS CORRECTLY? Space-time has been a hard concept for me to grasp, but I'm slowly getting it. I think. Am I conveying this in a way that works with the right concept of space-time?
Thank you!
1 Answer
- oldprofLv 710 years agoFavorite Answer
If the world were deterministic, but it isn't, you'd be able to trace back in time and space to "where it started." But with the advent of quantum mechanics, we've found the world is probabilistic and wave-like. Even big stuff, like school buses, have some (very tiny) uncertainty and wavelength. You and I have wavelengths and inherent uncertainties in location and momentum.
Space, the three spatial dimensions, and time, the one temporal dimension, are simply the environment we can sense and live in. Normally, we have no trouble in that as we, mankind, evolved in 4D space and have learned how to live within these four dimensions. Which is why we do it instinctively.
But, this is important, space-time gets weird and non-intuitive when we go real fast and/or get caught within the highly compacted (warped) space-time around huge mass, energy, or pressure sources like black holes. In either case, normal space goes from dS down to ds < dS, and normal time slows from dT down to dt < dT. Why? To keep the speed of light C at the speed of light C, no matter what.
In other words, we have dS/dT = C = ds/dt and the speed of light remains fixed as space and time compacts, gets smaller. And that, ta da, is the essence of both the special and general theories of relativity. Space and time are not fixed, they both adapt when stressed by speed or gravity to keep the speed of light in a vacuum at the same speed.