I have a physics question I've been wondering about for years...?

Question

According to Einstein no matter can exceed the speed of light...so what would happen if you had a giant wheel spinning in space and you bolted a rocket ship say 2 miles from the center of the wheel traveling at 20% of lightspeed and then you bolted a second ship securely to the wheel 20 miles from the center of the wheel...It would seem the second ship would need to travel faster than light to keep up...Would the outer part of the giant wheel just disintegrate or what?

Answer 1

The solution is quite simple. It would require an infinite amount of energy too spin the assembly so fast that any part goes the speed of light because the inertia of the outer parts diverges as they approach c. It is therefore not realizable.

Answer 2

It would require too much energy for the rocket ship 2 miles from the center to accelerate the whole thing up to that speed. As the velocity increases, so does the mass, which is created out of extra energy that would normally be put into acceleration. The harder the ship near the center pushes, the heavier the ship at the end becomes, so that no matter how much energy the first ship puts into accelerating up to 20% c, it will never get there. In this case, it is not only impossible for the second ship to get up to light speed, but for the first ship to go fast enough to propel the second one past light speed.

I'll sum it up for you in one line. According to Einstein, the ship near the center won't be able to reach 20% light speed.

Answer 3

To the above scenario I just applied the lorentz transformation to calculate the relative speeds. You can easily get the formula on google. The proof is very lengthy, but since you have enough calibre to think up this situation surely then, you can appy the lorentz transformation effectively.Even if you increase speed to more than 20% even then the speed will remain less than that of light.

As an afterthought i would like you tell about matter waves, whose phase velocities are given by c2/v where v

Answer 4

As matter approaches the speed of light, it's mass approaches infinity. In other words, it takes an infinitely large force to push it faster. So yes, your structure could not hold up and would be torn apart. In addition, the inner rocket would have to generate an infinite force. In fact, for a given speed it would have to generate more force than the outer rocket would have needed to accelerate itself to the same speed.

Answer 5

IANAP (I am not a physicist) but I believe what would happen is that the center would keep slowing down as you added the new extensions. You would need to add energy to speed it back up and the amount of energy needed to move the increasingly massive outer part (mass increases as the speed of light is approached) would eventually be infinite.

Answer 6

When you are doing closed system rotational motion problems like this, you have to consider the individual points along the system. If the rotational motion was that fast, you would still have a condition of infinite mass.

Answer 7

You are correct, the outer part of the wheel could not maintain its integrity. Relativity sets an upper limit on how stiff an object can be.

Answer 8

The problem with your logic is that we can't build this. Therefore it still proves Einstein's thoughts. Creating impossible scenarios can't debunk a theory. You need to create a possible solution for why his theory can't work.