This may seem like an unusual topic. However, I set out here to illustrate the fundamental effects of gravity upon the world we know. The strangeness is we all understand intuitively, the effects of gravity. We fear heights, we can catch a ball, we can aim closely to treble twenty, we can demonstrate how dextrously we can deploy the foil rapping from our lunchtime ‘sarny’ into the bin across the room. We intuitively understand gravity.
The interstellar medium in space exists separated from other matter. In attaining this distance from other matter it has accrued gravitational potential energy. This relentless energy in its separation from other matter will exist forever providing distance is sustained.
In physics there is a term ‘free expansion’. It is an isothermal process. It describes matter that has no ‘significant’ containment. That is a body of matter with near zero self gravity. For such a body, if we measure it’s mean kinetic distribution, or temperature, we find that at a later time that kinetic distribution although existing over a greater volume, (having expanded at the mean thermal velocity) is the same. That is, without containment and forced interaction, through expanding against zero force, matter retains its kinetic distribution and therefore the property we know as temperature does not evolve. It is isothermal over time.
Within this we have to reconcile the distribution of energy into the known available states. It is clear that transitional and rotational degrees of freedom cannot lose energy and conserve momentum without interaction. A molecule spinning or moving translationally through space cannot simply stop and emit a photon equal to its kinetic energy without breaking momentum conservation.
Therefore we have clarify the role of vibrational modes of molecular energy storage under such conditions. It can be seen that vibrational modes do not require momentum to describe them and therefore can spontaneously emit radiation and vibrate less or not at all as a result. Physics dictates that all meta stable thermal states have a non zero decay probability. Therefore, vibrational modes can only reduce the total energy content and energy in vibrational modes without interaction. We are left with the possibility that vibrational modes are not always compatible with other thermal states through conservation principles.
If a similar body of matter, due to density perturbation, finds itself under gravitational containment, then a wholly different outcome is inevitable. The matter falls and accelerates under gravity, freely exchanging as this happens a portion of the matter’s gravitational potential within the local collapse for immediate kinetic energy. Such collapses are isotropic within a uniform field of matter or spheroid in a non uniform field blending non-isotropy with conserved angular momentum. The collapse proceeds until the hydrostatic equilibrium condition is met. At that point the pressure at any point within the celestial body is the result of the weight of atmosphere above, under the respective gravity.
If this collapsing matter has sufficient mass then additional energy from nuclear burning will be initiated by core temperature and pressure conditions.
Irrespective of whether the protostar attains or fails to attain nuclear burning, the self gravitating body will evolve until a state of thermodynamic equilibrium is achieved.
Our collapsing or collapsed self gravitating body will then, due to the forced interactions of its containment, emit radiation. For a body of matter up to about 8 solar masses his process will continue until the matter is cold and degenerate. For higher mass bodies, the rapid collapse of the core in later stages of evolution will eject a large proportion of the matter back into space as a supernova. That ejected matter accruing gravitational potential with distance from the centre of mass that was internal energy from its material state.
However, we are left with the following conclusions;
1)Gravity forces interaction of matter.
2)That interaction produces radiation.
3)The quantity of radiation from a collapsed body in solitude is a function of mass.
4)The process of gravitational collapse and containment converts gravitational potential energy into kinetic (thermal) energy. The gravitational containment then forces the matter to beat itself against itself until the kinetic energy is radiated into space as a natural cooling process.
I would like to ask a question here;
If the Earth and the Sun evolved in proximity in space and were formed of the same initial composition at the same time but had equal mass, what would the netted radiative exchange be?