A problem in time dilation. To test myself how much I have understood about time dilation.?

Question

I and my friend can assemble a clock in one hour when at rest (not moving).

We are having two similar clocks. I am at rest whereas he is moving with a speed of 0.8C.

I start assembling a clock when my clock shows 1.00. He also starts AT THE SAME TIME assembling another clock. His time piece also shows 1.00 at the time of start.

When both of us finish the assembling, what will be the time in our clocks?

Will both of us finish the job simultaneously?

If not who will finish the job first?

Answer 1

I'm sorry, but I don't know what to assemble a clock means (English is not my native language).

Anyway with time dilation, when you have finished what ever you did with your clocks the one in the moving coordination finishes it at a later time when looking at from your coordination. Time in the moving coordination is moving slower.

Answer 2

The "absolute" time required to assemble the clock is the same, so the clocks will show the same time upon completion. HOWEVER, when he pops out of his time continuum, you will be an old man, your clock will have long since stopped ticking and he won't recognize you because though X amount of time passed for you, only one hour passed for him.

Now here's the cool bit. Your third friend magically went from rest to 1.3C. He started assembling his clock at the same time as you, and it showed the same time when he completed it, BUT he popped out of the continuum when you were a baby and has been waiting two lifetimes for your first friend :D

Answer 3

To answer this question we need to know what physical time is. Physical time is a velocity "c". Then we need to know what physical time does to a moving mass that it does not do in a stationary mass.

Mass is composed of electromagnetic energy. It is for this reason that all clocks are able to relate to a common value and measure units relative to it - whether in clumps of a tick - tock, or the vibrations of an atomic clock.

In the spaceship, the mass is moving 80 percent the speed of light. What this does is limit the movement of energy at right angles to direction of travel - it is for this reason that motions slow down in a moving mass. Were the spaceship to be moving at the speed of light, minus 2 ft/sec. then all the potential energy of movement would become frozen in direction of travel.

Were both clocks begun to be constructed at the same instant, the one in the spaceship would not have the "ENERGY" as the other to work with.

Answer 4

The time on each of your clocks will be the same when you finish. However, you will see him finish after you do, because to your reference frame his clock is moving slowly. The complicated bit, is that to him, you will finish after he will because in his refernce frame *your* clock is moving slowly.

There are lots of websites that will explain the phenomena with the help of animations, which is the easiest way to understand it. Here is one.

Answer 5

Read Steven Hawkings "A briefer history in time" it explains it very well, unfortunately it's been a while since I've read it so I can't remember for certain.

Answer 6

wow kool. well at the same time?