What is String Theory ?
In physics, string theory is a theoretical framework in which the point-like particles of particle physics are replaced by one-dimensional objects called strings. String Theory describes how these strings propagate through space and interact with each other. On distance scales larger than the string scale, a string looks just like an ordinary particle, with its mass, charge, and other properties determined by the vibrational state of the string. In string theory, one of the many vibrational states of the string corresponds to the graviton, a quantum mechanical particle that carries gravitational force. Thus string theory is a theory of quantum gravity.
Who invented string theory?
String theory represents an outgrowth of S-matrix theory, a research program begun by Werner Heisenberg in 1943 following John Archibald Wheeler's 1937 introduction of the S-matrix). Many prominent theorists picked up and advocated S-matrix theory, starting in the late 1950s and throughout the 1960s.
As so-called "Theory of Everything" candidate, string theory aims to address various theoretical conundrums; the most fundamental of which is how gravity works for tiny objects like electrons and photons. General relativity describes gravity as a reaction of large objects, like planets, to curved regions of space, but theoretical physicists think gravity should ultimately behave more like magnetism — fridge magnets stick because their particles are swapping photons with fridge particles. Of the four forces in nature, only gravity lacks this description from the perspective of small particles. Theorists can predict what a gravity particle should look like, but when they try to calculate what happens when two "gravitons" smash together, they get an infinite amount of energy packed into a small space — a sure sign that the math is missing something.
String theory could lead to multiple universes
String theory describes 10500 separate universes, with different constants of nature and even different laws of physics. Many physicists think this is a weakness of the theory, but Leonard Susskind thinks it could actually help us understand why our universe is so well suited to life.
Supersymmetry And Cosmological Signature
One essential quality of string theory is known as supersymmetry, a mathematical property that requires every known particle species to have a partner particle species, called a superpartner. (This property accounts for string theory often being referred to as superstring theory.) As yet, no superpartner particles have been detected experimentally, but researchers believe this may be due to their weight: they are heavier than their known counterparts and require a machine at least as powerful as the Large Hadron Collider at CERN to produce them. If the superpartner particles are found, string theory still will not be proved correct, because more-conventional point-particle theories have also successfully incorporated supersymmetry into their mathematical structure. However, the discovery of supersymmetry would confirm an essential element of string theory and give circumstantial evidence that this approach to unification is on the right track.
Even if these accelerator-based tests are inconclusive, there is another way that string theory may one day be tested. Through its impact on the earliest, most extreme moments of the universe, the physics of string theory may have left faint cosmological signatures—for example, in the form of gravitational waves or a particular pattern of temperature variations in the cosmic microwave background radiation—that may be observable by the next generation of precision satellite-borne telescopes and detectors. It would be a fitting conclusion to Einstein’s quest for unification if a theory of the smallest microscopic component of matter were confirmed through observations of the largest astronomical realms of the cosmos.
Comments
Post a Comment