Is string theory just nonsense? Has string theory been overturned?

No. There is also some useful knowledge in string theory, which can make people think and gain, so it can't be said that it is all nonsense.

Not nonsense, of course. String theory holds that the most basic thing is not particles, but "strings" one by one. There are 5 types of string theory:

Type 1, Type 2A, Type 2B, Hybrid O(32) (referred to as Hybrid O), Hybrid E8 E8 (referred to as Hybrid E). These are unified within a framework called "M theory".

I don't think so, after all, the world is so big that we haven't yet demonstrated a lot of things, and at this time, someone needs to be bold and imagine before someone can study and discover.

One of the basic ideas of string theory is that the basic unit of nature is not dotted particles such as electrons, photons, neutrinos, and quarks, but "strings" with very small chains.

The different vibrations and motions of strings produce a variety of different elementary particles, and energy and matter can be converted, so string theory does not prove that matter does not exist. The string scales in string theory are very small, and the basic principles that manipulate their properties predict the existence of several large-scale film-like objects, the latter being called "membranes" for short.

Intuitively speaking, the cosmic space we live in may be the D3 membrane in 9+1 dimensional space-time. String theory is now the most promising theory that unifies the elementary particles and the four interacting forces in nature.

In the course of their research, scientists who support string theory have come to the conclusion that the dark matter of the universe should be in a constant state.

A recent study suggests that the dark energy of the universe changes as the universe changes, which may pose a serious challenge to string theory. Not only that, but the amount of dark energy will also affect the fate of the entire universe.

If the dark energy increases, then the universe will face the end of a great tear, and all the atoms will be torn into subatoms by the powerful repulsion generated by the dark matter, and the entire universe will no longer have a macroscopic world.

If the dark energy remains unchanged or decreases, the universe may begin to contract under the influence of gravity, and eventually return to a singularity, starting again the next universe large**.

So why do the two need to be combined? Because they don't work together. The theory of relativity describes the macroscopic action of gravity, while quantum mechanics describes the smallest particles and the other three fundamental forces (the electromagnetic force, the weak nuclear force, which is necessary for the formation of a heavy nucleus, and the strong nuclear force, which combines protons and neutrons to form a nucleus).

For string theory, it was a dark age, especially when people found out that strings, can only vibrate in 10 and 26 dimensions, some people who tenaciously insist on studying string theory are regarded as ignorant and stubborn, outliers, pioneers of string theory, John of the California Institute of Technology, Schwartz was once asked wittily and sarcastically by Richard Feynman, John, then you have entered several dimensions today, Nobel Prize winner, Murray, the founder of the quark model, Gell-Mann is very sympathetic to those string theorists, So a conservation area for endangered string theorists was created at Caltech, so that scientists like John Schwartz would not lose their jobs.

The two pillars of modern physical theory are general relativity and quantum mechanics, but it is necessary to find a solution that satisfies both and whether string theory can be successful based on all the forces and matter currently known to the physical community.

Zheng Changlin 31415926 My friend said it very well and in detail, but it needs to be corrected: the 26-degree space and 11-degree space in the text are not commonly used physical words in the mainland, and should be changed to 26-dimensional space-time and 11-dimensional space-time.

In fact, anyone who understands quantum field theory can basically understand the theoretical framework of string theory. It's just that many of the results derived from string theory are too unbelievable, and many times they are not easy to accept in physics, and there is no experimental verification, so it can only be said to be a high-end and high-end Yangchun Baixue theory, which is very beautiful, but not real enough.

The basic idea and method used in string theory are exactly the same as those of modern quantum mechanics: find a classical object, reasonably define the generalized coordinates and generalized momentum, and do the arithmetic processing. In quantum mechanics, this is mostly the coordinates and momentum of point particles, in quantum field theory it is the momentum of small squares of infinite space (in the Hamiltonian sense), and in string theory, it is the momentum of various intrinsic vibrations of strings (if you have studied mathematical methods, you should remember the wave equation, which is the same thing).

The true meaning of the so-called "particles are vibrating strings" in string theory is here.

Many of the results of string theory are quite surprising, such as the problem of 26-dimensional space-time in Boson string theory. And string theory requires the use of very advanced modern differential geometry (including high-end things like Calabi Yau geometry).

I (see the famous book "The Strings of the Universe" for details).

String theory is a branch of modern physics, and it is also a very active research field. String theory attempts to unify the four basic interacting forces in nature: electromagnetic, weak, strong, and gravitational.

Instead of treating elementary particles as dots (i.e., zero-dimensional objects), string theory starts from considering the propagation of one-dimensional objects (which can be roughly thought of as line segments or circles) in space-time. On this basis, the equations of motion, quantization, theoretical symmetry, and so on are studied.

In the process of string theory, supersymmetry (supersymmetry is the object of supersymmetry theory), membranes, and duality (of different versions of the theory) were gradually introduced, which also gave rise to many mathematical problems and promoted each other with mathematical theory.

The "phenomenology" of string theory attempts to deduce the corresponding low-energy quantum field theory (Standard Model) from the high-energy string theory. It's a bit like the process of "deriving" classical mechanics from quantum mechanics.

String theory is string theory. String theory is physicists' belief that the entity of a point-like particle can be described as a tiny fragment of a one-dimensional "string." String theory can only "work" in many dimensions, and through string theory it is hoped that the causes of gravity can be solved.

String theory is a theory proposed by Su Shikan, who first understood the b-function describing strong interactions as a string that can be twisted and deformed, and then calculated from the theory that our objective world is a ten-dimensional space, and the strings vibrating in high-dimensional space will produce four kinds of interactions in three-dimensional space, namely gravity, electromagnetic force, strong interaction and weak interaction. Except for the three-dimensional space that we can perceive and time as one space, Hawking believes that they exist at every point and can only be observed on the Planck scale.