From: goldenfieldquaternions@gmail.com   
      
   On Friday, September 29, 2017 at 8:21:02 AM UTC-5, John Heath wrote:   
   > A car is moving at .1 c. The tire on the road at 6:00 o'clock , bottom ,   
   > is moving at 0 c as it is touching the road but at 12:00 o'clock , top ,   
   > the tire is moving at .2 c twice as fast as the car. Does this mean the   
   > car is limited to speed .5 c as at this speed the top of the tire will   
   > be moving at c twice as fast as the car ?   
      
   The velocity addition formula comes from the Lorentz transformations   
   from a frame with (x, t) to one with (x', t'). The transformation   
   of an infinitesimal increment is   
      
   dx' = gamma*(dx + vdt/c^2)   
      
   dt' = gamma*(dt + vdx/c^2)   
      
   with gamma = 1/sqrt(1 - v^2/c^2) the gamma factor and dx/dt = u.   
   It is not hard to see   
      
   u' = dx'/dt' = (u + v)/(1 + uv/c^2). The velocity u' obtains by   
   adding u and v.   
      
   It is then not hard to see that the velocity addition of .1c and   
   .1c results in a net .198c For larger additions this results in a   
   u' that is closer to the speed of light, but never surpassing it.   
   This means a rotating rod can't be perfectly rigid. Neutron stars   
   that can have a surface tangential velocity of .21c and the addition   
   of the surface velocity with material half way in ~ .1c have a   
   relative velocity of .102c. This means there is shearing of material.   
   This suggests the neutron matter is then a liquid and not a solid.   
   The old nuclear drop model of nucleons proposed much the same for   
   heavy nuclei, and it appears this may extend to neutron stars.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)