PASER is the acronym for Phonons Amplified Sound Energy Resonance. The first human induced paser was demonstrated by Ella Fitzgerald (1917-1996) doing a TV commercial for Memorex in 1971 (http://en.wikipedia.org/wiki/Ella_Fitzgerald). However, a theory of sound energy resonance of very high frequencies is still not completely established. On the other hand, what is empirically established is the relationship of the speed of sound to temperature in degrees relative of Celsius not in degrees absolute of kelvins. In order to establish absolute temperature relationship, the thermal dependence of gravity must be formulated. Thermal gravity can be defined as the fifth fundamental force of Nature distinctively independent of Newton’s gravity, of the electromagnetic force, of the weak nuclear force, and of the strong nuclear force. The last three are also defined as exchange forces by several effective quantum field theories. Hypothetically, a physical formulation of a thermal force can become the singular force uniting all fundamental forces. Moreover, it also unites Einstein’s theory of general relativity and quantum mechanics. Thermal force exists for all adiabatic processes. In the largest perspective, for the entire universe, an adiabatic system is equivalent to an isolated system, where neither matter nor energy enters or exits the specified thermodynamic system.

Thermal pressure (��) can be defined as the rate of change of thermal force per unit of area. Newton was the first to calculate the rate of change of pressure with density by supposing that temperature stays practically constant deriving the isothermal speed of sound, which was wrong until Laplace gave the correct deduction that the pressure and temperature change adiabatically in sound waves propagation. As already described in the thread on the thermal origin of gravity, the thermal force is given by this equation: ��=(����²/��⁴)Δ��/��² where Δ��=��₁��₂=(��₂-��₁)��₁ such that ��₁=1kelvin and ��₂>>��₁ if and only if both ��₁ and ��₂ are rational numbers. Therefore, the thermal pressure �� is defined as ��/�� or ��/�� where �� is the area perpendicular to the direction of motion, �� is the thermal energy equivalent to heat, and �� is the volume of the adiabatic system.