drkitten Penultimate Amazing

Join Date: Mar 2004 Posts: 21,629

wackyvorlon Originally Posted by Say, hypothetically, that we have an object emitting light that is travelling toward us at the speed of light in a vacuum.



"Traveling at the speed of light" is like division by zero -- the best way to understand it is through a limit process (what happens when our object is travelling very very close to the speed of light), because the answers you get when you look directly at the question are nonsensical.



Quote: The light travels to us, and arrives blueshifted because of this. Now, to my understanding if we were to measure the speed of this blue shifted light, it would be c. Like wise, if an observer on board said hypothetical object were measure to the speed of the light coming from us, it would be travelling at c.



Quote: If we then have two atomic clocks, one on the object and one beside us.



Quote: If we compare the rate of the clock on board the object to our clock, we find it has slowed. were travelling at the speed of light, we would observe that the clock has stopped altogether.



Quote: Thus one second in our frame of reference is not in fact the same as one second in the frame of reference for the moving object. Now, here's the part that's broken my brain. Time is the denominator in measurements of speed. How can the light we emit, and the light the object emits, both be measured at the same speed when the rate of time here differs from the rate of time there?



We see, however, that he is transmitting a light with a wavelength of X/k and a frequency of c/(X/k) (his wavelength has been cut by 100x, while his frequency went up by 100x, say.) Thus we measure the speed of his light as the same. Can't be done. Any "object" possesses mass, and therefore cannot travel at the speed of light."Traveling at the speed of light" is like division by zero -- the best way to understand it is through a limit process (what happens when our object is travelling very very close to the speed of light), because the answers you get when you look directly at the question are nonsensical.This is true, even when stuff is only travelling very close to the speed of light.Since atomic clocks have mass, it can't be travelling at the speed of light.Yes. In fact, if the clocktravelling at the speed of light, we would observe that the clock has stopped altogether.Because distance also distorts, which is why you get the blue shift. Time gets longer, distance gets shorter. In particular, the moving observer -- the one who isn't us -- will see that he is transmitting a light with a wavelength of X, and a frequency of c/X.We see, however, that he is transmitting a light with a wavelength of X/k and a frequency of c/(X/k) (his wavelength has been cut by 100x, while his frequency went up by 100x, say.) Thus we measure the speed of his light as the same.