Flat 1x1 meter plate. Heat source indicated by red arrow. The rest is in space. No sun exposure at all.
Some of the photons will exit through the gaps between plates. No problem. My question is about the photons that do make it from plate to plate.
One photon leaves the first plate and is received by the second. Is this transfer of heat 100% efficient? If not, why? If the energy does not go into heat, where does it go?
A variant of this question would be a hypothetical sphere heat source inside a much larger hollow sphere in space. Is heat transfer through radiation from the small sphere in the center to the larger outer sphere 100% efficient?
Let's define the term: "100% efficient" is taken to mean that one unit of energy carried away by a photon from the source delivers one unit of energy to the destination.