XPost: sci.physics   
   From: bill.sloman@ieee.org   
      
   On 14/02/2026 3:20 am, Stefan Ram wrote:   
   > Bill Sloman  wrote or quoted:   
   >>                        Energy has mass   
   >   
   >    Counterexample: The photon. It has energy, but no mass.   
      
   Depending on how you define mass. Newton had one definition.   
      
   Einstein had another. Light pressure does imply that a photon has momentum.   
      
   --   
   Bill Sloman, Sydney   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)