The simplest way I can put my question is like this: velocity is described as distance/time. That's a fine approximation at non-relativistic speeds. The closer an object gets to the speed of light, however, the more time slows for that object. So a distant observer would record one velocity for a near-light speed craft but, due to the slowing of time the passengers on the craft would record a much higher velocity.
Put another way, light travels as ca. 300,000 km/sec. But if I were to travel at close to the speed of light, from my perspective I would be travelling faster, as my seconds would be much slower than normal. It might appear to me that I was traversing 300,000 km in .5 sec, for example. I know physicists make a distinction between 'proper' time and 'coordinate' time. Measuring by proper time, i.e. the perspective of the traveller, seems to allow for perceived speeds greater than light. Is that right?
Also, is there an agreed perspective from which to establish 'coordinate' time? A kind of SI unit of velocity-observation? I suppose what I mean is, since time varies with velocity and everything is moving, what is the baseline from which we measure the velocity of objects. (And if you tell me it's the speed of light, I'm going to have a very big headache.)
Finally, is there a means of getting around this by measuring velocity independent of time?
Put another way, light travels as ca. 300,000 km/sec. But if I were to travel at close to the speed of light, from my perspective I would be travelling faster, as my seconds would be much slower than normal. It might appear to me that I was traversing 300,000 km in .5 sec, for example. I know physicists make a distinction between 'proper' time and 'coordinate' time. Measuring by proper time, i.e. the perspective of the traveller, seems to allow for perceived speeds greater than light. Is that right?
Also, is there an agreed perspective from which to establish 'coordinate' time? A kind of SI unit of velocity-observation? I suppose what I mean is, since time varies with velocity and everything is moving, what is the baseline from which we measure the velocity of objects. (And if you tell me it's the speed of light, I'm going to have a very big headache.)
Finally, is there a means of getting around this by measuring velocity independent of time?
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