Thank you Pierre-Normand for replying.

You wrote: "On the return path, the travel time is shorter due to the source rushing towards the light ray. It may therefore seem like the two effects cancel out. However, since the distance traveled forward is longer, more time is accrued for the light ray to catch up with the mirror than is saved on the shorter return path. Because of that, there still is time dilation, and calculation shows that the same gamma factor is in play."

Would it be possible for you to write down how this can be achieved, for I don't understand?

The way I see this is simply the length the path of light will have for the first leg would be increased
(L + vt) and the second leg would be foreshortened (L- vt) which, as you mentioned, seems to cancel the effect.
What happens during the first leg which gives the gamma factor is what I still don't understand.

However, this was only part of the problem as S.R. would identify the path itself as being contracted by a factor of gamma, giving (gamma L+vt) + (gamma L - vt) = 2 gamma L . With c being constant,...this seems to give us a time contraction cancelling the effect of the vertical clock..

I sure that I'm misunderstanding something, but don't know what exactly.

thank you for your time

Grampa Dee

Grampa Dee wrote:

"Within a moving ship,relative to an outside observer, a light clock is introduced having a light signal going up horizontally" ....sorry, I meant vertically...

My question concerns the gamma factor for s.r... I'm simply am posing a question as I am not a scientist.
Within a moving ship,relative to an outside observer, a light clock is introduced having a light signal going up horizontally and then being reflected downwards. The observer outside the spaceship will calculate light signal (up and down) having a greater distance to travel relative to the observer inside the ship, however still having a velocity of c; this will bring about an observed time dilation on the part of the moving ship....of course the same can be said for the observer within the spaceship, if the outside observer had a light clock as well, but we will only focus on the first example.

What would happen if the light clock was positioned horizontally instead?
I personally can't see how the horizontal clock would be synchronized with the vertical one.

Grampa Dee

I personally believe that Aristotle was an empiricist along with being a great thinker. 
He seemed to have pointed out the first law of Newton (inertia); although he didn’t believe this law was valid, it was only because he didn't believe in a vacuum space; When speaking of the “void”, Aristotle writes…

Physics
Book IV
Part 8 

“Further, no one could say why a thing once set in motion should stop anywhere; for why should it stop here rather than here? So that a thing will either be at rest or must be moved ad infinitum, unless something more powerful get in its way. “


Aristotle goes on to write:

“Further, in point of fact things that are thrown move though that which gave them their impulse is not touching them, either by reason of mutual replacement, as some maintain, or because the air that has been pushed pushes them with a movement quicker than the natural locomotion of the projectile wherewith it moves to its proper place. But in a void none of these things can take place, nor can anything be moved save as that which is carried is moved.” 

Some have assumed this to mean that a force was needed in order to keep an object in motion...
I read it differently. First, when he said "nor can anything be moved save as that which is carried is moved", it was about a body moving within a void, that which he didn't believe could be possible.


I think the statements above might possibly be indicating  some form of aerodynamic implication, instead. The natural movement of the body is the downward movement.
Therefore, if we let the first statement stand as is :

“a thing will either be at rest or must be moved ad infinitum, unless something more powerful get in its way. “ (in a void)

Then, the horizontal movement performed by the force is maintained because: 

“the air that has been pushed pushes them with a movement quicker than the natural locomotion of the projectile wherewith it moves to its proper place”.
things can take place, nor can anything be moved save as that which is carried is moved.” 

To me, this could easily mean that the horizontal movement of the object is maintained without the action of dropping down (natural movement) due to the medium…air in this case.