Physics is about describing what we observe. It is not about explaining what something is. So far, there is no Theory For Everything. That means that any theory, like Newton’s laws of motion, Einstein’s General Relativity, or Quantum mechanics, have their area of application. None of them are correct – they just yield answers that are sufficiently accurate when used in the appropriate scenario. But even with a TFE that can be applied to anything – which would be fantastic – it still does not say what something is. But, what is energy? What is time? What are forces? Those are philosophical questions, or perhaps metaphysical ones. In the following, Rudolph Draaisma shares his thoughts on what forces are.
I haven’t found a general definition of what a physical principle is, but there are several examples to illustrate it. The main one is the First Law of Thermodynamics, the consequence of which is that energy cannot be created, nor destroyed. It is also known als the law of conservation of energy. Other conservations laws, such as for momentum, are physical principles also. They have in common that any violation of them, would be in conflict with basically everything else in physics, one inconsistency causing the other. In this sense the laws of Newton are also physical principles. Any violation of them, would invalidate the whole of physical science. However, we do not know what energy, time and matter is, so any theory on those would be worth considering, as long as it doesn’t come in conflict with known physical principles.
From the above we can conclude that we also don’t know what a force is and so my theory, that they arise from the transfer of energy and as such are not causal entities, is not in conflict with any physical principle. If it were, it would come in conflict with the laws of Newton, but it doesn’t. It’s just a deeper insight, not changing the practice of physics in any way, but eliminating the heavy confusions that exist otherwise.
However, if forces are not applied, but arise from the transfer of energy, then these forces must be seen as a resistance against that transfer. Then the question arises what causes this transfer at all, what drives it, if not a whatever force and why the resistance? To answer this question we have to take a closer look at how energy behaves.
The dispersion of energy
There is the indisputable observation that energy tends to spread out, to disperse in the surroundings, unless it is hindered to do so. However, it cannot be fully hindered, but only slowed down – perfect insulation does not exist! Once energy is released from its chemical or nuclear bonds, it will disperse irresistibly, finally to become heat at ambient temperature in the Earth’s atmosphere. The same we see happen in the universe, the stars pouring out tremendous amounts of radiation energy, all dispersing into space. If it were not so, “the world”, our planet and life as we know it, could not exist and so this, the tendency of energy to spread out, indeed is a physical principle. Actually, “tendency” is a too weak expression, because the irresistibility of it makes it a force, i.e the “dispersive force” of energy.
The common formulation of the Second law (as per Rudolf Clausius) is not a physical principle, because a violation of it, simplified being the ‘spontaneously’ reversed flow of heat, is not in conflict with any known physical principle, least of all with the First Law, as long as energy balance is maintained. Therefore this formulation must be seen rather as a rule (following from observations), than as a law. IF however such a reversed flow of heat (or any flow) would not disperse, then it would violate the physical principle that the dispersion of energy is. Hence, if the Second Law would be formulated in terms of irresistible energy dispersion, then it would become a “real” law, a physical principle!
What forces are
The “dispersive force” of energy is in my view the only “real”, i.e. causal force in Nature. All other forces are not applied, but result from this dispersive force. These are not only mechanical forces, but also potential, electrical and thermal ones. Indeed, a temperature difference is not the “drive” for heat to flow, but is the result of it. Heat flows (disperses) ALL BY ITSELF (the dispersive force) and a temperature difference arises as the resistance against it. Mechanical inertia (Newton’s second law) is also such a resistance (not Mach’s Principle in GR).
Better than curved time-space in General Relativity, the principle of forces arising as the result of resistance against the dispersion of energy, makes it “natural” that a gravitating object in free fall is not subjected to an inertial force (Aristotle would “love” this). This is because there is no transfer of energy, as in standard physics it is acknowledged that the object’s mechanical energy remains constant, and thus there is no “resistance”, thus no force of inertia arises. On impact with the ground, a large resistance is present and so both mechanical (inertia) and thermal (temperature) forces arise, to let the energy involved disperse to its maximum extend. Mind that if the involved materials of and around the impact would have an infinite specific heat capacitivity, meaning they have no resistance to take up heat energy (sort of “suck” it up instantly), no increased temperatures would arise at the impact.
Likewise, if we burn a fuel in an open flame and the air around would “suck” up the released energy as fast as it is released (= power), the flame would have the same temperature as the surrounding air. In extremum, in the center of stars, like our Sun, tremendous amounts of energy are released from nuclear bonds, that have no way to go in the short time it happens – it takes a few hundred thousand(!) years to reach the surface of the Sun. The dispersive force of this energy (proportional with the power of it) causes a temperature of millions of degrees to overcome the hugh flow-resistance that the material of the Sun constitutes. It also causes a tremendous mechanical force, balancing against the gravitational pressure, the latter being what caused and maintains the nuclear process,