From: niklas.holsti@tidorum.invalid   
      
   On 2021-12-23 9:10, JF Mezei wrote:   
   > Saw an issue in a flat Earther video that caused me to wonder.   
   >   
   > Say you have a long pole that spans the distance from Earth to the Sun   
   > but floating somewhere in space. This pole is not compressible and   
   > cannot bend. (built from unobtainium for sake of discussion).   
      
      
   Such unrealistic assumptions can make for wrong conclusions, so beware.   
      
      
   > If I push the pole at one end to move it say 5cm.  I am not asking the   
   > pole to move anywhere near speed of light.  However, doesn't the force   
   > of acceleration I put in at one end propagate to the whole pole   
   > instantly instead of taking 8 minutes to travel ?   
      
      
   No. Your "push" is a compression wave, or sound wave, that propagates at   
   the speed of sound in the pole. Of course, if you assume unobtainium,   
   you can assume or deduce a very high sound speed. But as the forces   
   between the atoms of the pole are mainly electromagnetic, the sound   
   speed will never exceed the speed of light, and is /much/ lower in real   
   materials.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)