The string theory gained momentum with its own perfection some 30 years ago, with the aim of solving the difficult problems in basic physics, including reconciling the contradictions between relativity and quantum mechanics。
In a broad relativism, events are continuous and determinative, meaning that each cause matches a particular, partial effect. In quantum mechanics, events resulting from the interaction of subatomic particles occur by leaping (quantitative leaping), with probabilities, not certainty。
Simply replacing infinity particles with tiny vibration rings, in the words of michael faraday, it seems too wonderful to be unrealistic. These vibrations produce quarks, electrons, glues and photons. Quantum uncertainty cannot tear space to shreds, and there seems to be a workable quantum gravity theory at last。
More beautiful than the text is the math behind it, which excites some physicists. To be sure, string theory has had a disturbing impact. These strings are too small to be detected and exist in space of up to 11 dimensions. These dimensions are folded into complex shapes. No one knows how these dimensions fold, but it is certain that certain configurations eventually produce the force and particles we know。
Many physicists believe that string theory unites quantum mechanics and gravity。
Then physicists realized that the dream of a single (unified) theory was just an illusion. After completing the powerful “standard model” of particle physics in the 1970s, they wanted the story to be repeated in string theory. Like many mature theories, string theory has become rich, complex, difficult to deal with in a number of ways and has wide-ranging implications. Its tentacles have reached many fields of theoretical physics。
The mathematics of string theory has been applied in such areas as cosmology and condensation physics. Today's string theory looks almost fractal. The closer people explore any corner, the more structures they discover. Some dig deep in particular “cracks”, while others widen their horizons and try to understand larger patterns. As a result, the string theory today contains a lot of things that look no longer string. Those tiny chords are thought to penetrate every particle and force known to nature。
Even when the mathematical tools of string theory are used in physics, physicists struggle to deal with the central tension of string theory: can it teach researchers how gravity and quantum mechanics reconcile
“the problem is that string theory exists in the realm of theoretical physics,” said juan maldacena, an international ias mathematical physicist, who may be the most outstanding person in the field today. “but we still do not know how, as a gravity theory, it is associated with nature。
Quantum field explosion
The string theory emerged as the culmination of the theory of everything in the late 1990s, when mardasena revealed that the string theory containing five-dimensional gravity was equivalent to the four-dimensional quantum field theory. This “ads/cft” duality seems to provide a map that captures gravity by linking it to an ancient and well-understood quantum field theory, the hardest object in physics。
This linkage has never been considered a perfect realistic model. The five-dimensional space in which it lives has the geometry of anti-de de sitter, which is nothing like our universe。
But when researchers look into the other side of this duality, they are surprised. Most people assume, of course, that quantum field theory is well understood. Our understanding of them has proved very limited。
These quantum field theories were developed in the 1950s to harmonize narrow relativity and quantum mechanics. They worked well for a long time. But today, when physicists re-examine “the part that you thought you understood 60 years ago”, ias physicists say you'll find “shocking results”, which is totally unexpected. “every aspect of quantum field theory that we understand is wrong.”
Researchers have developed a great deal of quantum field theory over the past decade or so, each of which is used to study different physical systems. The outbreak of this new quantum field theory reminds us of physics in the 1930s, when a new type of particle, the accidental appearance of the cipher, caused frustration in the rabbi: "who found this?" by the 1950s, the proliferation of new particles had led enrico fermy to complain, "if i could remember the names of all these particles, i would have become a botanist."
Only when physicists find more basic particles (such as quarks and glue) do they begin to see their direction in the jungle of new particles. Now many physicists are trying to do the same thing with quantum field theory。
The symmetric theory is a starting point. You can start with a simple quantum field theory, which is expressed in the same way at great and small distances. If these particular types of arguments are fully understood, the answer to the deep question becomes clear。
String theory math
Perhaps the area most benefiting from the dynamic development of string theory is mathematics itself. Ias researchers explain how some of the seemingly intractable mathematical problems are solved by imagining a string. For example, how many spherical bodies can be accommodated by a kalabi-hill current (complex folding shape used to describe time and space)
Mathematicians are trapped. A two-dimensional chord can swing in such a complex space, and when it twists, it gets new insights, like a mathematical multi-dimensional cord. That's einstein's famous physical thinking: the idea of flying with beams reveals e=mc^2. The idea of falling from upstairs is a flash of light: gravity is not a force, it's an attribute of time and space。
Using the physical intuition provided by strings, physicists have proposed a powerful formula to solve the nesting problem. They use tools that mathematicians don't allow to produce. Then, after string theorists found the answer, mathematicians proved it in their own words。
String theory also makes an important contribution to cosmology. The role of string theory in thinking about the mechanisms behind the expansion of the universe — in the immediate aftermath of the big bang, the quantum effect meets the gravitational side — is “absolutely powerful”。
The expansion model is entangled in string theory in many ways, especially in the multiverse (the concept of a multiverse is that our universe may be one of an infinite number of universes), each of which was created by the same mechanisms that created our own universe. Between string theory and cosmology, the idea of an infinite universe is not only accepted, but even taken for granted by many physicists. The choice effect will be a very natural explanation of why our world is like this, and in a very different universe we will not be here to write this article。
This effect may be the answer to a big question that string theory should have solved. As gross said: “what singles out this particular theory (standard model) from unlimited possibilities?”
Construct a new view
At the very least, the mature version of string theory provides a powerful new approach to seeing how seemingly incompatible descriptions of nature are simultaneously correct. The discovery of a dual description of the same phenomenon largely sums up the history of physics. A century and a half ago, james clark maxwell discovered that electricity and magnetism were two sides of a coin. Quantum theory reveals the connection between particles and waves. Now physicists have string theory。
Once we detect space with strings rather than particles, we see things differently. If it is too difficult to use quantum field theory to get from point a to point b, then re-think the issue in string theory. In cosmology, string theory “packaged physical models in a way that was easier to think about, and it might take centuries to put all these clues together into a coherent picture。
Einstein also tried to find a theory of everything, but it also ended in failure, without prejudice to his genius. Maybe the real picture is more like a map on an atlas, each of which provides very different information and is different. The use of the atlas will require physicists to master multiple languages and methods at the same time. Their work will come from many different directions。
We are in the most exciting physical age since quantum mechanics emerged in the 1920s. But nothing will happen soon。
