# Special Theory of relativity confusion

1. Dec 21, 2015

### Shehreyar Khan

My Question is very interesting. I want an exact answer after correct assessments. Let there is a box or rocket or something in which light starts from point A to point B. When Light is generated from point A, at the exact point that thing box or rocket or frame moves from point X and it moves until Light reaches from A to B, now as it reaches B, that thing box or rocket stops and it covers the distance from point X to point Y and stops at that point. Now Distance D1 be the distance light covers from A to B, which can be found using formula (d = ct) and let D2 be the distance between point X and point Y. We can find D2 using (v * t') v is the speed of rocket or box, while t' is the relative time. If there is another way ot find it then kindly state it. My question is that can D2 be equal or greater than D1? and we know v has a limit that it should be less than c. Which distance will be greater? D1 or D2?

2. Dec 21, 2015

### Staff: Mentor

Where is t' measured?
Both for the frame where the whole setup is described, and for the frame of the box/rocket: no, D2 cannot exceed D1.

3. Dec 21, 2015

### Shehreyar Khan

Yes Sir, I am considering the experiment with reference to an outside observer, who is observing the rocket moving and inside that rocket the light beam moves from A to B and in same time the rocket move from X to Y... Any possibility that D2 is greater than D1? as the time will also be dilated the t' is the dilated time and the observer will consider the dilated time...

4. Dec 21, 2015

### Staff: Mentor

No.
t' is shorter than t, and v is smaller than c. There is no way the product can be larger than c*t.
This is assuming the light is moving through a vacuum of course.

5. Dec 21, 2015

### Shehreyar Khan

Thank you sir