Towards the end of the 19th century, Kelvin pronounced as the "clouds of physics" 1) the failure of the Michelson-Morely experiment to detect an ether wind, 2) the violation of the classical mechanical equipartition theorem in statistical thermodynamics. And he believed that the removal of these clouds would bring physics to an end. But as we know, the removal of these clouds led to the two great breakthoughts of modern physics: 1) The theory of relativity, and 2) to quantum mechanics. Towards the end of the 20th century more clouds of physics became apparent. They are 1) the riddle of quantum gravity, 2) the superluminal quantum correlations, 3) the small cosmological constant. Furthermore, there is the riddle of dark energy making up 70% of the physical universe, the non-baryonic cold dark matter making up 26% and the very small initial entropy of the universe. An attempt is made to explain the importance of these clouds for the future of physics. Conjectures for a possible solution are presented. they have to do with Einstein's last query: "Can quantum mechanics be derived general relativity", and with the question is there an ether?
Deep Dive into The clouds of physics and Einsteins last query: Can quantum mechanics be derived from general relativity?.
Towards the end of the 19th century, Kelvin pronounced as the “clouds of physics” 1) the failure of the Michelson-Morely experiment to detect an ether wind, 2) the violation of the classical mechanical equipartition theorem in statistical thermodynamics. And he believed that the removal of these clouds would bring physics to an end. But as we know, the removal of these clouds led to the two great breakthoughts of modern physics: 1) The theory of relativity, and 2) to quantum mechanics. Towards the end of the 20th century more clouds of physics became apparent. They are 1) the riddle of quantum gravity, 2) the superluminal quantum correlations, 3) the small cosmological constant. Furthermore, there is the riddle of dark energy making up 70% of the physical universe, the non-baryonic cold dark matter making up 26% and the very small initial entropy of the universe. An attempt is made to explain the importance of these clouds for the future of physics. Conjectures for a possible solution
One great scientific event of the 19 th century was Darwin's theory of evolution. The theory made a lot of sense provided a sufficient amount of time was given. But as Kelvin, at his time a towering authority in physics, had pointed out (by the theory he and Helmholtz had developed), the sun could not be more than 100 million years old, explaining its radiative energy output to result from the conversion of gravitational potential energy into heat through its shrinking to a smaller diameter. The conclusion by Kelvin was a big blow to Darwin's theory, because it was difficult to believe that a time of 100 million years was long enough to explain the evolution from bacteria to homo sapiens. Today, of course, we know that by the release of energy from nuclear fusion, the sun has a lifetime of about 10 billion years, sufficiently long for Darwin's theory of evolution. This is a good example of how careful one should be in drawing such far reaching conclusions as were drawn by Kelvin, and as they are drawn today with our present (most likely still) limited knowledge of the physical universe. We are though fairly certain, that ordinary matter, of which we and all the stars are composed, makes up only 4% of the material content of the entire universe, with 26% made up from completely unknown heavy particles (the non-baryonic cold dark matter), and 70% of an unknown energy ("quintessence") not even made up of particles.
When Kelvin tried to bring the house of physics in order, not only with regard to the time scale he gave Darwin for his theory of evolution, it was his opinion that apart from a few “clouds”, physics is an almost completed science. These clouds were: 1) The failure of the Michelson-Morely experiment to detect an ether wind, and 2) the failure of classical statistical thermodynamics to explain the specific heat of solids at low temperatures. As we know today the removal of these clouds led to the two great breakthroughs of 20 th century physics: The theory of relativity and quantum mechanics. Adding the discovery of nuclear energy, not anticipated by Kelvin, there were actually all together three clouds.
At the turn from the 20 th into the 21 st century there again appear new clouds over the horizon, not less mystifying than were Kelvin’s clouds. Drawing from Kelvin’s experience, it is very unlikely that these clouds can be removed by the extrapolation of present theories, like the extrapolation of general relativity from the four space-time dimensions of every physics laboratory, to more than four space-time dimensions, and from zero-dimensional point particles to higher dimensional brane particles. What is mathematically obvious, as are these extrapolations, is physically most likely wrong. We must rather look for radical new ideas, such as suggested by Einstein’s last query: “Can quantum mechanics be derived from general relativity?” In paraphrasing Bohr (with regard to Heisenberg’s failed unified field theory), it is not that at first glance this conjecture seems to be crazy, but if it is crazy enough to be true.
At the turn of the 21 st century, the most puzzling cloud of physics was and still is the unsolved problem of quantum gravity: How to quantize Einstein’s gravitational field equations. Of the four fundamental forces, the electromagnetic, the weak, the strong, and the gravitational force, only the first three of these can be quantized in a mathematically consistent way, but this turns out to be very difficult for gravity. The problem seems to be solvable by making such outlandish conjectures that there are more than the three dimensions of space, and that the point-like structure of elementary particles, (required by the postulates of the special theory of relativity), must be replaced by strings or higher dimensional surfaces (membranes). In making these conjectures, the followers of this line of thought seem to have forgotten that points, lines, and surfaces are abstract elements of Euclidean geometry, having no place in physics, where everything must be measurable.
The argument in favor of strings is that the infinites in relativistic quantum mechanical calculations can there be avoided. But because of Heisenberg’s uncertainty relation this is an illusion, because to measure the vanishing diameter of a string, or the thickness of a membrane requires an infinite amount of energy. For point-like particles, quantization works for renormalizable theories, like quantum electrodynamics, where the subtraction of two infinities is set equal to the value of an observed quantity. This renormalization “trick” does not work for quantum gravity.
While for quantum gravity the problem is “mathematical”, it is for the superluminal quantum correlation (EPR experiment) “physical”. About this problem, countless papers and books have been written, making all sorts of philosophical conjectures, with the most outlandish one the “many worlds interpretation”. The reason for the failure to find a reasonab
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