Translated from french by Grok

In the 20th century, theory in the field of physics made such progress that it left far behind any attempt on the part of experiment; with the direct consequence being the appearance of a new phenomenon: abundance!Many physicists think that the situation has never been so painful in their branch as it is now. We could doubtless say, somewhat cynically while following the truth, that among them there are those nostalgic for the Newtonian era.It is true that from 1666 onward, I. Newton’s theory of gravitation became very powerful; however, it was so powerful that it became a true religion. In this way, no one dared even think that it could be inaccurate, let alone false. Humanity had to wait until 1905 for a heretic to finally appear: A. Einstein!Nevertheless, the real problems arose with the advent of quantum mechanics, because it bothers the scientist with the freedom it offers him in terms of interpretation. This is one of the reasons why some scientists consider it incomplete.The phenomenon of abundance was truly born in the 1960s, and since then it has only grown bigger and bigger. It was at that time that the various string theories were born, based on the hypothesis that elementary particles behave in the same way as superstrings in a space-time that can have, depending on the axioms of each theory, 10, 14, 24 or even 26 dimensions…Of course, we are not going to present all the theories of those years and those that followed, as that would require another article; more realistically, we will examine the most important common point offered by contemporary theories, namely the rarity or even the absence of experimental facts.A physical theory not confirmed by experiment is nothing more than a mathematical model. This is why the following question is important: What does the expression “a physical theory” mean?The mathematical level used by contemporary physics has reached such a degree that it is very difficult, even for a specialist in theory, to find a formula that can be experimentally verified. Consequently, as often happens, current theoreticians are content—or more precisely are more or less socially constrained—to check whether their theory is logically consistent, for lack of time, instead of exploring other, admittedly more adventurous, directions of research that would finally allow them to obtain these much-desired experimental criteria.And indeed, contemporary theories have serious weaknesses in the area of predicting observable phenomena with the current means of science.Two examples, so that our reader does not think we are abusing him by not talking about real things.Einstein, wanting to unify gravitation with electromagnetism, used an asymmetric tensor in his new theory, thinking it was the best possible generalization of relativity, which dealt only with symmetric tensors. On this point he was absolutely right, because purely mathematically this theory is truly aesthetic; the problem is that no experiment has been found to confirm it! To be really precise, in general we now think that this theory is not the right one to achieve the great unification—that of the four forces—because it would have great difficulty explaining the existence of bosons, which is experimentally certain.The other example concerns the theory of parallel universes, also called the many-worlds or branching theory. Logically, it is perfect. Only here too the problem of experiment exists, but it is much more difficult than in the previous example because it is a metatheory based on quantum mechanics theory and differs from the orthodox theory only in the interpretation of experiments. We think it is one of the strangest but also one of the most interesting theories that currently exist.Surprisingly, this situation is reminiscent of Antiquity. Indeed, at that time the abundance of theories was just as significant; the absence of an experimental criterion gave rise to a multitude of theories. The growth of this multitude was aided by another resemblance to our era: the desire to theorize everything. This attitude is not prejudicial in itself; however, it becomes so when experience does not sanction these creations.At the limit, the reader might still say that it is desirable for such creative activity to exist—don’t we have the same thing in the artistic domain? The last word explains everything!Because the real problem lies there: science without experiment is worth no more than art! The Greek thinkers, creators of theories, very quickly realized that what mattered was not validity, leading to a tendency to improve the argumentation of theories. Argumentation became the keystone of persuasion. (The attentive reader will have understood that a small extrapolation of these remarks would suffice to explain the birth of philosophy!) And it is true that the logical coherence of an argument that goes against common sense can shake the convictions of even the most pragmatic among us. Do not forget, dear reader, that the only way Diogenes found to counter Zeno’s assertions about the impossibility of motion was to start walking!But suppose for a moment that Diogenes had been paralyzed—what would he have done? Of course, this was only a metaphor; what we want to express is the following fact: without access to experiment, it is impossible to prove anything about the truth of a logically consistent theory.The decline of the scientific thought of the ancient Greeks was due to the lack of experimental research. Thus we think that on the one hand experimenters must further develop their techniques, and on the other hand—and this is the essential reason for the existence of this article—that we theoreticians must finally learn that a mathematical model is not a physical theory and that we must constantly compare theory to reality. For however beautiful the aesthetics of a theory may be, it remains monstrous if it is not true.

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