I have just recently thought of this query. However, I can find no evidence of any experiments ever being carried out on the effect of zero gravity on black body radiation.Perhaps someone here has heard of such an experiment. Or maybe someone can predict the answer? What does relativity predict the effect would be?
By 'zero gravity' I mean the geodesic path which the centre nucleus of every celestial body takes through the cosmos and whose movement over time is therefore wholly determined by the law of gravity - such as exists at the centre of our planet.
The gravitational escape velocity shell which applies at the surface of the Earth is far greater than that which applies to the specific free falling 'gravity shell' which the ISS occupies as it orbits the planet.
The lateral/rotational velocity of the surface of the planet is ???? mph slower than the actual relative escape velocity of the surface gravitational shell [which in turn, is wholly determined by the length of the radius of the shell from the centre of the free falling nucleus which exists at the gravitational centre of the planet].
Consider the (not unreasonable but speculative notion) that gravity is a force which propagates radially out into empty space from the centre source at the speed of light [as determined by the Planck constant]. By doing so, we can further speculate that the lateral velocity of the ISS can be interpreted as the movement of empty space which is separate from that of the radial folding of empty space. Since the velocity of the propagation of the folding of free space 'gravity', equates as a constant speed of light, the only variable equation [in the specific gravity shell which the ISS occupies over time] is it's lateral velocity in free space relative to the constant radial folding of free space.
This is why I believe that any experiments carried out in free fall zero gravity regarding it's affect on black body radiation would throw some light on this hypothetical model.
Would it not follow from this that the thermal equilibrium of a black body measured within the free falling zero gravity volume of the ISS, would be redshifted relative to that of an identical black body situated on the surface of the Earth?
The question was set in the 1st paragraph; 'I can find no evidence of any experiments ever being carried out on the effect of zero gravity on black body radiation.Perhaps someone here has heard of such an experiment. Or maybe someone can predict the answer? What does relativity predict the effect would be?'
The results of such an experiment would help me in finalising a proposition I have for an alternative model of physical reality - of which I made a poor attempt at trying to describe. Basically, the model proposes that there are only 2 forces which exist in the universe. The 1st is the folding of free space in a vacuum [gravity]. The rate of the radial propagation of the force of gravity in empty space is a universal constant and is determined by the period of time it takes to fold a 2 dimensional line at the speed of light into a circle with a radius of 1 Planck length. This constant represents the value of Planck time.
The second force is the lateral movement of free space in a vacuum which occurs at 90 degrees to the radial folding of free space over Planck time. The only thing which connects the separate forces of lateral movement and radial folding is the synchronicity [or resonance] which occurs between the 2 at variable particular lateral velocities.
The 2 forces can be regarded as existing in perfect equilibrium when the lateral velocity over time exactly equals the escape velocity of the gravity shell in which it exists.