# Faster than c (help)

Discussion in 'Physics & Math' started by Visitor, Sep 14, 2002.

1. ### VisitorRegistered Member

Messages:
25
Thought experiment.

Pick a neutron star, any neutron star. It's spinning in space but we are somehow able to stop it temporarily and place a pole through the center and then the star resumes spinning. If the pole is long enough it seems that at some point along the pole we can place a traveller who would be moving at faster than light.

I like physics but I'm not a pro , why won't this work?

Last edited: Sep 14, 2002

3. ### EmfuserRegistered Senior Member

Messages:
90
Because the person will need to be accelerated to the speed of light. You can't do that because your mass increases as you accelerate. As the traveller's mass increases, so does the amount of force required to continue accelerating them. Eventually you end up with an extremely massive traveller that the neutron star won't have enough energy to accelerate any more.

5. ### James RJust this guy, you know?Staff Member

Messages:
37,130
The pole will bend and eventually break, before it reaches the speed of light. There is no such thing as an infinitely rigid pole.

7. ### zanketHumanValued Senior Member

Messages:
3,777
The pole bends because the signal that "tells" the pole to move travels along the pole no faster than the speed of light. For example, light travels about 300,000 km/s. When the neutron star resumes spinning, the section of the pole that is 300,000 km away from the star will not move until at least 1 second later. The section that is 600,000 km away will not move until at least 2 seconds later, and so on. This is why there is no such thing as an infinitely rigid pole. If the pole were long enough and didn't break, it would curl around the star.