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Q & A: Inertia of radiant energy

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Most recent answer: 08/08/2011
Q:
As I understand it, energy and matter are equivalent forms, yet it seems that the difference is that radiant energy has no inertia and matter does experience inertia. What is it about something like a neutron and the energy of sunlight that sums to a neutrons rest mass that accounts for inertia?
- Devon (age 24)
Lansing
A:
Actually, radiant energy (light) does have inertia, and it does contribute to gravity. For a box of radiation with energy E, the inertial effects are exactly the same as for any object with rest energy E, so long as the radiation is bouncing around with net momentum zero.

Mike W.

(published on 08/08/2011)

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