From: intuitionist1@gmail.com   
      
   On Friday, November 2, 2018 at 5:25:34 PM UTC+3, Lawrence Crowell wrote:   
   > On Friday, November 2, 2018 at 12:24:01 AM UTC-6, ben...@hotmail.com wrote:   
   > > On Thursday, November 1, 2018 at 10:21:57 PM UTC, Tom Roberts wrote:   
   > >> ...   
   > >> For test particles the GR prediction is unambiguous:   
   > >> regardless of the test particle's mass (including sign, if any) it   
   > >> "falls downward" toward a positive mass and "falls upward" away from a   
   > >> negative mass.   
   > >>   
   > >> While there is currently no experimental evidence of antimatter's   
   > >> behavior in gravity, the mass of every known antiparticle is   
   > >> unequivocally positive.   
   > >> ...   
   > >   
   > > I am not clear how it is shown that antimatter unequivocally has   
   > > positive mass?  As both positive and negative test masses are attracted   
   > > to the positive mass of the earth, then how can attraction to the earth   
   > > be used to distinguish between a positive and a negative test mass?   
   >   
   > It makes little sense that antimatter has negative inertial mass. The   
   > particle antiparticle interaction would give mc^2 - mc^2 = E = 0, where   
   > experiments measure photons. The gravitational mass is an open   
   > questions, and an experiment at CERN is being set up to measure this   
   > with anti-hydrogen atoms.   
   >   
   > LC   
      
   This is actually not correct.   
      
   If you take the time to work it out (by considering the interactions between   
   the four classes of particles I mention), you will actually find that the   
   energy and momentum of a particle of type (I,A,P) has to have a factor of   
   IAP in front of the usual definition, so the momentum p = IAPmv, the kinetic   
   energy E = IAPmv^2/2, and the rest mass energy is IAP mc^2.   
      
   So your assumption that negative inertial mass implies negative energy is   
   not correct in general.   
      
   In actual fact, the rest mass energy is positive for particles of class A   
   and D, and negative for particles of class B and C.   
      
   Now, antiparticles are of type D (well at least according to the claim made   
   here), and therefore have positive energy, so the total energy released upon   
   annihilation of a particle-antiparticle pair is positive (and equal to   
   2mc^2), as expected.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)