- #1
arizzirv
- 1
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All,
I am having a problem resolving the common examples that are used to explain time dilation as a consequence of the constancy of the speed of light. I can't help but assume that there is something simple and fundamental that I'm missing here. I apologize in advance for forcing you to use your imaginations, but I am as yet unable to post images.
In the time dilation example, a pulse of light is issued from an inertial reference frame (perhaps the floor of a boxcar) and travels straight upward to a mirror which reflects it back to the source. The path traveled by the light, according to the observer in that frame, is simply twice the distance between the source and the mirror. This is compared to a longer distance seen by an outside observer due to the relative motion of the frame.
In the simultaneity example (usually also using train cars) light pulses are issued from equal distances on either side of an observer. The light from the front of the car reaches the observer before the light from the rear of the car, resulting in the lack of observed simultaneity in contrast to an outside observer.
Here is my trouble...
In the first example, the only way the light could travel straight up and down with respect to the boxcar is if its horizontal velocity is equal to that of the car. Otherwise, the light would travel toward the rear of the car as it moved upward. So I see this as having the following components :
Vz = c
Vx = c + V (isn't this impossible?)
where V = boxcar, Vx = light horiz., Vz = light vert.
But in the second example, the only way the light could reach the observer at two different times is if the two pulses were NOT carrying the car's velocity. This means:
Vfx = -c
Vrx = c
where Vfx = forward pulse horiz., Vrx = rear pulse horiz.
I hope someone could take a few moments to set me straight on this.
Thank you
I am having a problem resolving the common examples that are used to explain time dilation as a consequence of the constancy of the speed of light. I can't help but assume that there is something simple and fundamental that I'm missing here. I apologize in advance for forcing you to use your imaginations, but I am as yet unable to post images.
In the time dilation example, a pulse of light is issued from an inertial reference frame (perhaps the floor of a boxcar) and travels straight upward to a mirror which reflects it back to the source. The path traveled by the light, according to the observer in that frame, is simply twice the distance between the source and the mirror. This is compared to a longer distance seen by an outside observer due to the relative motion of the frame.
In the simultaneity example (usually also using train cars) light pulses are issued from equal distances on either side of an observer. The light from the front of the car reaches the observer before the light from the rear of the car, resulting in the lack of observed simultaneity in contrast to an outside observer.
Here is my trouble...
In the first example, the only way the light could travel straight up and down with respect to the boxcar is if its horizontal velocity is equal to that of the car. Otherwise, the light would travel toward the rear of the car as it moved upward. So I see this as having the following components :
Vz = c
Vx = c + V (isn't this impossible?)
where V = boxcar, Vx = light horiz., Vz = light vert.
But in the second example, the only way the light could reach the observer at two different times is if the two pulses were NOT carrying the car's velocity. This means:
Vfx = -c
Vrx = c
where Vfx = forward pulse horiz., Vrx = rear pulse horiz.
I hope someone could take a few moments to set me straight on this.
Thank you