After insisting that backradiation is real physics and not just fiction, Roy Spencer takes on to determine the temperature of empty space in Yes, Virginia, the “Vacuum” of Space Does Have a “Temperature“.
By a clever use of quotation marks, Roy states something which can be “interpreted” in “any way “you” want”.
Let us here try to give Roys’ statement a meaning and see if it makes sense.
In Mathematical Physics of Blackbody Radiation I analyze a model of the radiative transfer of heat energy between two radiating bodies interacting through electromagnetic waves in a vacuum connecting the bodies.
Each body consists of a system of material resonators in form of a lattice of atoms and the temperature of each body is the sum of the temperatures of all frequencies, with the temperature of each frequency being the energy (kinetic + potential energy) of the corresponding resonators. Each body thus has a temperature as a measure of the total energy of the resonators of the body.
The two bodies interact by electromagnetic waves in a vacuum connecting the bodies, but there is no reason to attribute a temperature to the electromagnetic waves since they do not have material nature. One can thus say that the vacuum has no temperature and only acts as a means of communication between the two bodies allowing the warmer body to transfer heat energy to the colder.
As an analogy one may think of two persons communicating by mobiles (electromagnetic waves) with the “temperature” of each person being the level of knowledge or “excitation” and the more excited person transferring excitement to the less excited. In this case there is no reason to attribute excitement to the electromagnetic waves transferring the excitement.
OK, so we conclude that a vacuum has no temperature, but does it then follow that the “empty space” surrounding the Earth has no temperature? No, because the “empty space” is not empty, but can be viewed as “the other body” willing to absorb heat energy from a warmer Earth.
The conclusion is that empty space has no temperature, but the Earth is not surrounded by empty space and radiates heat energy to a surrounding of low temperature. Again it seems that Roy’s speculations do not describe physics, nor does John O’Sullivan.
Recall that Roy has a leading position in climate science and thus it matters to all of us if what Roy says is correct or not.