Is perspective faster then light? Look at one star cross billions of miles and look at the next star.?

Question

Say I had a stick that was long enough to touch one star and I moved it to touch the next one I was looking at would the stick not have to move faster then light?

Answer 1

Hi drgns77

I think I know what you're getting at here - it's an interesting question. What is stopping you from being able to whip your stick across a billion light years in a few seconds is the structure of your stick. When you move your end of the stick, the other end of the stick doesn't move simultaneously. The information that the stick is moving travels along the length of the stick to the far end at a finite speed, this speed is the speed of sound in the stick. The speed of sound in a material is a function of the material's rigidity. In order for the speed of sound in a material to equal the speed of light that material would have to be infinitely rigid (which isn't possible).

But let's not let that stop us!

Suppose instead of a floopy long stick we use a laser pointer. Suppose you wish to sweep the laser over a billion light years from A to B, while you stand even further away at C (A,B,C form an isoceles triangle). We can sweep the pointer across the billion light years from A to B in a few seconds - is this faster than light travel? Again the answer is "no". This time it is because the light beam doesn't actually travel from A to B. To help visualise this, imagine the light beam as a series of photons (which it is). When pointed in one spot the beam looks like a beam, but when you whip it across the billion LY distance you get a "spray" of photons along the path from A to B. In fact the photons are travelling from you (at C) to the line joining A and B - so there's no FTL travel from A to B.


I hope this helps!
The Chicken

Answer 2

Good question. You've discovered one of the standard paradoxes put forth in many texts on relativity.

The answer has to do with the fact that the impulse you send down the stick cannot travel faster than the speed of light. The noticeable droop in very long objects provides a useful clue. Nothing is ever perfectly rigid, and the deviation from rigidity is more noticeable the longer an object is. Relativity puts an upper limit on how stiff the stick can be. It will take a finite amount of time for the tip to "know" that the base has moved. The signal is propagated by a physical force--usually the electromagneti one--whose signals travel at or below the speed of light in a vacuum.

So no material thing will move faster than lightspeed. Now consider your "perspective" idea. Where does the information reside? Only in your head. No message is sent from one star to its neighbor, nothing has been communicated faster than lightspeed.

Answer 3

Nothing except mind moves faster than light. So if u wish to touch a star with an unimaginable length the impulse you will give it from the earth will travel at a speed less than that of the speed of light. In usual cases we use a small stick to push something and it seems to us that the impulse had taken no time to resch the object. But actually the speed is very high and less than that of light. So it is imaginable that the impulse will take more time than light to reach the star.

Answer 4

Sorry but your question is strange to me. Moving your stick you did not define the speed at which you were moving it, so no one can be certain that it would move faster than the speed of light.

I am afraid you are comparing apples to oranges in this instance, you can perform a similar experiment on a smaller scale, use a stick to touch can A and then move your stick to touch another can B - you still have not proven that your stick moved faster than the speed of light.

Your fundamental problem lie in the use of power of observation - how would you be able to see that your stick has touched your second object without observing it in the first place? To be able to observe the situation you'd have to see it, to see it, you'd have to allow light to reach you first. So your proposed scenario does not test anything about the speed of light nor whether your stick moves faster or not.

Answer 5

Read "relativity for the masses" by Stephen Hawkin...The tip of the stick will not move faster than the speed of light.

Answer 6

No. Because u'd have to apply a much great force to move the tip of the stick from one star to the other, than u would be thinking. Probably, it would take more than ur lifetime to move the stick.

Answer 7

ROFLMAO