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levokun
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The term "mass" is the source of many conflicting opinions among the authors writing on relativity theory.
Different authors denote by this term different concepts.
Quite often even the same author denotes by mass different concepts in his different writings.
For instance when introducing his famous diagrams Richard Feynman used the concept of invariant mass of a particle defined by equation ##m^2=p^2##, where ##p## is four-momentum. But later in his Feynman Lectures on Physics he preferred to define mass by the equation ##E=mc^2##. Thus defined mass ##m## obviously increases with increase of total energy ##E## and hence of speed of a particle.
The equation ##E=mc^2## usually referred to as the super-famous Einstein equation, though Einstein himself preferred another definition: ##E_0=mc^2##, where ##E_0## is the rest energy, or energy of a particle at rest. To a certain extent the partial source of confusion was the term "rest mass" used by him.
Different authors denote by this term different concepts.
Quite often even the same author denotes by mass different concepts in his different writings.
For instance when introducing his famous diagrams Richard Feynman used the concept of invariant mass of a particle defined by equation ##m^2=p^2##, where ##p## is four-momentum. But later in his Feynman Lectures on Physics he preferred to define mass by the equation ##E=mc^2##. Thus defined mass ##m## obviously increases with increase of total energy ##E## and hence of speed of a particle.
The equation ##E=mc^2## usually referred to as the super-famous Einstein equation, though Einstein himself preferred another definition: ##E_0=mc^2##, where ##E_0## is the rest energy, or energy of a particle at rest. To a certain extent the partial source of confusion was the term "rest mass" used by him.
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