In this blog post, we will look at the scientific validity and philosophical nature of string theory and question its essence.
Einstein’s final dream, famous for the theory of relativity, was to unify all the forces in the world into one. His last quest, which was called the “unified field theory,” was not successful, and since then, many physicists have been trying to do so. Under the perspective of dividing physics into the relativity theory, which deals with the macroscopic world, and quantum mechanics, which deals with the microscopic world, the three forces that can be explained within the microscopic world, namely electromagnetic force, weak nuclear force, and strong nuclear force, have already been unified through various efforts. However, since only gravity is explained within the theory of relativity, which deals with the macro world, the final process of combining the three unified forces and gravity is not smooth. To overcome this difficulty, the ‘superstring theory’ appeared as a puzzle in the unified field theory proposed to overcome this difficulty, and this article will examine the validity of this theory.
String theory is a theory based on quantum mechanics, so it requires the reproduction of such a microscopic world, and in particular, the conditions at the beginning of the universe’s creation provide an environment for the verification of string theory. However, this situation cannot be reproduced with current technology. In addition, a theory in science can only exist within the boundaries of science if it can be proven by experiments. Should we blame the lack of scientific and technological capabilities for not being able to verify string theory? I don’t think so. String theory tries to complete everything within its own mathematical logic, but it is criticized for being obsessed with mathematical completeness for its “theoretical” proof, and it seems that the conclusions it makes cannot be verified experimentally. It requires experimental conditions that go beyond simply reproducing the conditions of the early universe. This makes string theory seem to be asserting itself as an ideal realm that can only exist within a mathematical logical system. Researchers of string theory have a responsibility to present a method of verifying a theory that is not “ideal” so that it can exist within the scope of science. If not, they may be free to continue researching the theories they are studying, but it would be difficult to assert their validity at will, wouldn’t it? The philosopher of science Karl Popper advocated the “principle of falsifiability,” emphasizing that the more likely a scientific theory is to be disproved, the better it is as a theory. The theory of superstring seems difficult to exist as a good theory. There is no way to disprove it, at least for now, and it seems unlikely that we will be able to do so in the near future.
It is said that the current level of mathematics is insufficient to deal with string theory. It is also said that many advances in mathematics have been made solely to deal with string theory. And the mathematical complexity of string theory is indescribable. Also, as mentioned earlier, this theory has no experimental evidence. In other words, string theory is seen as speculative. If the language of science is mathematics, then string theory is just a branch of philosophy described in the language of mathematics. But if that’s the case, then what is the value of string theory? No one would think that string theory could do the same thing that philosophy has done for human intelligence. It may not be science, but how should we view string theory, which cannot reveal its value unless it is science? It is certainly not a theory that would limit its significance to the development of mathematics to describe itself.
So why are string theory researchers so obsessed with string theory? Physicists are said to be attracted to the symmetry found in the laws of physics. String theory also fascinates many physicists in terms of its symmetry. They believe that there is a physical truth in symmetry. Can a physical theory be correct only when it implies symmetry? The well-known physicist and astronomer Kepler tried to explain the arrangement of the planets around the sun only with the geometric symmetry of the five Platonic solids and spheres that exist in the world. This seemed to fit well, but the solar system, which should have only six planets in such a structure, contains eight planets, and the orbits of the planets, which should be spherical, have been modified to elliptical orbits by Kepler’s laws, which he ironically discovered. The funny thing is that Kepler never gave up his belief in geometric symmetry. This historical anecdote seems to predict the current state of superstring theory researchers if the superstring theory turns out to be wrong. A scientist should base his or her research direction solely on scientific facts. An individual scientist’s passion can be the source of his or her will and enthusiasm for research, but such an attitude cannot be considered a scientific attitude. Then, where should the capabilities of numerous scientists be focused in an attitude based solely on reason?
Some string theory researchers have said that string theory is an unfortunate theory that was discovered centuries ahead of its time. This is a view that is mainly held by Edward Witten, a leading string theory researcher. Edward Witten is a giant in theoretical physics, and he has such an influence in the physics community that people say, “All of you here are great, but he has reached a level of divinity that cannot be surpassed.” It may be correct to say that it is ahead of its time. However, it is more accurate to say that it is on the border between precociousness and immaturity. Since string theory has hardly been experimentally proven, the experimental basis on which it is based is very weak. Where can we find the basis for this? If string theory is a theory that can be discussed in the field of particle physics, the final theory currently recognized in particle physics is the “Standard Model” theory. The Standard Model, which is considered to have almost completed its experimental verification with the discovery of the Higgs boson, still has many parts that need to be filled in and clarified. Everyone knows that buildings can be built on a solid foundation. So, we may need to focus more on the areas where we know more and can find more clear things. In such an uncovering, the foundation of string theory, which is currently just a collection of complex mathematical formulas, may be formed. Of course, sufficient research must continue to enable string theory to serve as a strong candidate for the ‘unified field theory’. However, I hope that physicists will become more active in moving beyond their blind obsession with physical or mathematical symmetry and draw their attention to many other areas of theoretical physics.
I would like to conclude this article with the words of Stephen Weinberg, a physicist who was once at the forefront of string theory. “I have no intention of dissuading string theorists. But the world may be just as we have always known it. It is a world of the Standard Model and General Relativity.”
