Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

[Phys-l] Is light pure energy?



In the last paragraph of chapter 15 of The Feynman Lectures on Physics,
Feynman says that,
"This theory of equivalence of mass and energy has been beautifully
verified by experiments in which matter is annihilated--converted
totally to energy: An electron and a positron come together at rest,
each with a rest mass m_o. When they come together they disintegrate
and two gamma rays emerge, each with the measured energy of m_o c^2."
The phrase "converted totally to energy" bothers me. I think I would
have said something to the effect that the matter is converted into
light that has the same amount of energy m_o c^2 that the matter had
prior to the conversion. Is light pure energy?