« on: 16/09/2013 10:40:20 »
Now how do we know how fast the car was travelling? Our experimenter on earth will have told us the length of the test track, and will transmit a signal every second. To make it simple, let's say the car travels 100m in 100s. So we receive 100 time pulses, after which we see that the car has travelled 100m. The effect of the blue shift has indeed been to increase the frequency with which we perceive the time signals c ompared with our clock, but whilst the car may appear to have been travelling faster than 100m/s by our clock, it hasn't done so by his clock - and that is the one we use to measure speed.This is close to what I was asking, if it could appear to us that something could be travelling faster than light due to it being in a different frame of reference to us, without actually travelling faster than light in reality. Which I am assuming is the case judging by your answer of "whilst the car may appear to have been travelling faster than 100m/s by our clock".