From: heathjohn2@gmail.com   
      
   On Tuesday, March 20, 2018 at 8:14:27 AM UTC-4, Lawrence Crowell wrote:   
   > 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.   
      
   Yes and this has been verified in particle accelerators. We have a speed   
   limit of c. If I were 1 light year tall movement of my hands would be   
   limited to the speed of light. A chance to feel first hand that a vacuum   
   is very real. If i rotate a rigid disk it's rotation speed would be   
   limited to the point that the outside of the disk reaches speed c. If   
   the same rigid disk is used as a wheel for a car would the car's speed   
   be limited to .5 c where the top of the tire reaches c ? Keep in mind   
   speed addition not being 2 + 2 = 4 has to do with energy. The same is   
   true of Newtonian physics where twice the energy is not twice the   
   speed. The issue is will the car be limited to .5 c as this would be the   
   speed that the top of the tire is moving at c. This is a mechanical   
   limitation of a rigid wheel not the amount of energy to reach the limit   
   of speed c.   
      
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