Hypothetical question about speed and distance across space

In summary: The speed of light only applies to massless particles.In summary, the hypothetical scenario of an impossibly sturdy and light pole attached to the earth and spanning a distance of 200 million light years into space would not result in the end of the pole moving faster than the speed of light. This is because any motion along the pole would propagate at the speed of sound in the material, not the speed of light. Similarly, pushing on the pole to communicate would also result in the movement only propagating at the speed of sound, not instantaneously as one might expect. The speed of light only applies to massless particles, not massive objects like the pole.
  • #1
furix
2
0
I have two hypothetical questions about breaking the speed of light that has been bugging me for quite a while.

Question 1:

Assume an impossibly sturdy and light pole is attached to the earth. Its length spans a distance of 200 million light years into space. Since it is anchored on earth, it rotates with the earth. Unbelievably, as the Earth spins, the end of this pole (or any part of it) does not hit any bodies in space.

Wouldn't the end of this pole be moving across the universe in a full 360 rotation in 24 hours? Moving at speeds way over the speed of light?

[PLAIN]http://img823.imageshack.us/img823/8533/question1k.jpg
(ignore the "tap like morse code, that is for question2)
http://img823.imageshack.us/img823/8533/question1k.jpg Question 2:

This same pole, is not attached on Earth and does not rotate with the earth. However, it can be pushed (remember, it is extremely sturdy and light). At the opposite end of this pole is a morse code machine. Couldn't we effectively communicate across 200 million light years instantaneously?

[PLAIN]http://img23.imageshack.us/img23/6382/question2c.jpg
http://img23.imageshack.us/img23/6382/question2c.jpg Does that make any sense?
 
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  • #2
Welcome to PF. This is a common question. The answer is pretty simple: An impossibly stiff rod is impossible. In reality, Any motion will propagate along the rod at the speed of sound in the rod.
 
  • #3
As stated above, welcome!

For the second question, remember that the electrons used to send the message are only traveling at the speed of light, so it will just take 200 years for the Morse code to reach the other end of the pole (assuming no dissipation in the signal).

Good thinking, though. These types of mind experiments were how the Theory of Relativity was developed in the first place. Glad you asked. :smile:
 
  • #4
Thanks for the responses!

Did you mean speed of sound or light in regards to the answer to question 1? So you're saying that the rod at 200 million light years across is being whipped around the earth, slowly creating a spiral?

In regards to question 2, so by pushing on the rod, it would move along the rod at only the speed of light? So the end wouldn't move for 200 million years, but it's moving from the beginning like a ripple at the speed of light?

Thanks!
 
  • #5
Oh, sorry, I misread that it was being used as a morse code machine. The movement would still only propogate at the speed of sound of the material.
 

1. How does speed affect travel distance in space?

Speed and distance in space are directly related. The faster an object travels, the further it can go in a given amount of time. This is due to the concept of velocity, which takes into account both speed and direction of motion. The higher the speed, the greater the distance traveled.

2. Can an object travel at the speed of light in space?

According to Einstein's theory of relativity, it is impossible for an object with mass to travel at the speed of light. As an object approaches the speed of light, its mass increases infinitely and it would require an infinite amount of energy to continue accelerating. However, objects without mass, such as photons, can travel at the speed of light.

3. How long would it take to travel to a distant planet at high speeds?

The time it takes to travel to a distant planet at high speeds depends on the distance between the two planets, the speed of the spacecraft, and the acceleration and deceleration of the spacecraft. With current technology, it would take several years to travel to even the closest planets at high speeds.

4. What is the fastest speed ever achieved by a spacecraft in space?

The fastest speed achieved by a spacecraft in space was by NASA's Juno spacecraft, which reached a speed of 165,000 miles per hour (266,000 kilometers per hour) during its mission to Jupiter. This is about 37 times faster than the speed of sound on Earth.

5. How do scientists measure the speed and distance of objects in space?

Scientists use various methods to measure the speed and distance of objects in space, including radar, spectroscopy, and triangulation. Radar uses radio waves to measure the distance to an object, while spectroscopy measures the wavelengths of light emitted by objects to determine their distance. Triangulation involves using the positions of multiple objects to calculate their relative distances and speeds.

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