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pmb_phy
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In another thread dextercioby posted the http://https://www.physicsforums.com/showpost.php?p=406225&postcount=13
dextercioby - What's Q theory? I assume that it pertains to quantum mechanics??
I thought you made a good point, one I'm quite familiar with. But there is something I wanted to comment on regarding this point. When someone speaks of the mass of a particle (i.e. what you referred to as relativistic mass) they are speaking about classical particle dynamics. Not all of classical particle dynamics carries over to quantum mechanics (which I assume Q theory pertains to). Many often used concepts in relativity can't be used in the quantum domain. For instance, there is no concept of a worldline in quantum theory (or at least its quite different than in classical relativity). I don't believe that there is even a 4-velocity in quantum theory. These are imporant points to keep in mind when applying relativity to quantum mechanics.
Einstein never used the term relativistic mass so one can't say for sure. He simply referred to "mass", or "inertial mass". In his text TMR he spoke of the inertial mass of a particle as being altered when there is a gravitational field present. What he was referring to was the quantity [itex]m = m_0 dt/d\tau[/itex] when v << c. This is not the same quantity as [itex]m_0[/itex] since [itex]dt/d\tau[/itex] does not equal one when v << c and there is a gravitational field present.
Pete
I want to address this interesting comment here so as not to divert the other thread.And to answer your question,YES,people working in Q theory never use the concept of "relativistic mass".They use "energy" (zero-th component of the energy-momentum 4-vector)
dextercioby - What's Q theory? I assume that it pertains to quantum mechanics??
I thought you made a good point, one I'm quite familiar with. But there is something I wanted to comment on regarding this point. When someone speaks of the mass of a particle (i.e. what you referred to as relativistic mass) they are speaking about classical particle dynamics. Not all of classical particle dynamics carries over to quantum mechanics (which I assume Q theory pertains to). Many often used concepts in relativity can't be used in the quantum domain. For instance, there is no concept of a worldline in quantum theory (or at least its quite different than in classical relativity). I don't believe that there is even a 4-velocity in quantum theory. These are imporant points to keep in mind when applying relativity to quantum mechanics.
I'm sorry but I don't understand your point here. Responsible for what? If you mean that Einstein didn't "like" relativistic mass after he completed relativity (in 1915) then that is a common misconception. What Einstein did not believe in a was a velocity dependant mass for a "material particle" (his term, not mine). That is often misconstrued to refer to relativistic mass. It might be said that Einstein did use the concept of (relativistic) mass in his own work such as his 1916 GR paper (in section 16) in his text The Meaning of Relativity (TMR) (pages 100-102) and in his book Evolution of Physics.dextercioby said:Einstein is held responsable for that.Though he had 0 contribution to QFT.
Einstein never used the term relativistic mass so one can't say for sure. He simply referred to "mass", or "inertial mass". In his text TMR he spoke of the inertial mass of a particle as being altered when there is a gravitational field present. What he was referring to was the quantity [itex]m = m_0 dt/d\tau[/itex] when v << c. This is not the same quantity as [itex]m_0[/itex] since [itex]dt/d\tau[/itex] does not equal one when v << c and there is a gravitational field present.
Pete
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