What is string theory? (in detail)?

Answer 1

EVerything you ever wanted to know about the string theory: http://en.wikipedia.org/wiki/String_Theory

Answer 2

String theory is one of the latest attempts by Physics (and in saying latest I should qualify that the theory has been postulated back in the mid 80's) to create a 'Unified theory', or a group of mathematical equations that governs, well everything - a 'Theory of Everything'.

While it may sound fanciful, a brief look at the history of Physics shows that phenomenon and forces can be explained using mathematics - that the actions and interactions of certain forces can be written into a single, or at least a few mathematic equations.

Perhaps one of the most famous Physicists, Albert Einstein, wrote one of the most famous equations - E = Mc^2, an equation that explains how mass and energy are related. While Isaac Newton had previously explained the maths behind gravity, he gave no explanation as to how it was transmitted as a force, something Einstein managed with General Relativity. Essentially, Physics of the past centuries has been a mathematical quest to explain the forces of the Universe with Maths, and with each advance, the Maths that explains the forces gets simpler and simpler.

Now the four, most basic forces of the Universe, as we understand, are Gravity, Electromagnetism, the Strong Nuclear Force and the Weak Nuclear Force. Gravity is a large scale force, working on the massive scale of stars and planets, while the latter three are the small scale forces, working on the scales of atoms and the particle within them, electrons, protons and neutrons, and further down through the subatomic realm, the realm known as the 'Quantum'. Gravity, as explained above, is neatly and proficiently explained by Einsten's theory of General Relativity, while the other three forces are explained in the theory of Quantum Mechanics.

However, these theories, while precisely and exactly explaining their respective forces, are contradictory. General Relativity dictates a calm, placid Universe of certainty, while Quantum Mechanics explains a jittery, uncertain Universe where things we take for granted, like concepts of location and time, can come into question. It sounds strange, but it is not inconceivable for a particle to be effectively in two places at once, in this theory.

Their basic premise and mathematics are so far removed that any attempt to reconcile them fails miserably. Thankfully, the only situations in which both theories apply are Black Holes (collapsed stars that form a 'rip' in space, an infinitely dense, infinitely small point), or the very beginning of the Universe, rather appropriately termed the 'Big Bang'. However, when the maths IS applied in these cases, the results are nonsense - essentially, when you need to use both, the maths breaks down. One of the world's foremost string theorists, Brian Greene, likened them to squabbling siblings.

This is where String Theory comes into play - it is a theory that hopes to explain both these forces under a single concept - and thus, a single set of mathematics. It postulates that all matter and energy is simply the result of the different vibration pattern of a 'string' of energy. These strings are tiny, inconceivably small, but the different ways in which they vibrate would represent all matter and all force in the Universe, a 'Theory of Everything'.

However, this Theory comes at a high price - some versions of string theory have 10 dimensions, or even 26! However, these things can be explained, if dimensions are 'contracted' or so tiny as to not be apparent to us.

All in all, string theory hopes to explain the Universe in one simple, sweeping theory that encompasses all four forces and matter in a simple piece of mathematics.

Answer 3

String concept perspectives the Universe as being composed of interacting vibrating strings analogous to the strings of a guitar, fairly then the corpuscle visualization of rely that Isaac Newton orginally defined. the full concept revolves around Planck's consistent. Mathematically it bases a manifold which emerged from The "Euler Equation "wherein they desperate 11 dimensions of the area shape as unfavorable to Einstein's mere 4 dimensions of Relativity concept yet another string concept surfaced modeled after strings concept referred to as "Superstring concept. This concept allude to 20 six dimensions to describe our suroundings in this Universe. and that i presumed I rather have a no longer undemanding Time attempting to understand sturdy geometry of three dimensions in extreme college.

Answer 4

If you combines enough strings you get a rope.

Answer 5

It probably couldn't get more detailed than this >> http://en.wikipedia.org/wiki/String_theory

Answer 6

watch the video

so ul understand

even more u askt for:)

Answer 7

STRING THEORY

Introduction
In particle physics, a theory that attempts to merge quantum mechanics with Albert Einstein's general theory of relativity. The name string theory comes from the modeling of subatomic particles as tiny one-dimensional “stringlike” entities rather than the more conventional approach in which they are modeled as zero-dimensional point particles. The theory envisions that a string undergoing a particular mode of vibration corresponds to a particle with definite properties such as mass and charge. In the 1980s, physicists realized that string theory had the potential to incorporate all four of nature's forces—gravity, electromagnetism, strong force, and weak force—and all types of matter in a single quantum mechanical framework, suggesting that it might be the long-sought unified field theory. While string theory is still a vibrant area of research that is undergoing rapid development, it remains a purely mathematical construct because it has yet to make contact with experimental observations.

Relativity and quantum mechanics
In 1905 Einstein unified space and time (see space-time) with his special theory of relativity, showing that motion through space affects the passage of time. In 1915 Einstein further unified space, time, and gravitation with his general theory of relativity, showing that warps and curves in space and time are responsible for the force of gravity. These were monumental achievements, but Einstein dreamed of an even grander unification. He envisioned one powerful framework that would account for space, time, and all of nature's forces—something he called a unified theory. For the last three decades of his life, Einstein relentlessly pursued his quixotic vision. Although from time to time rumours spread that he had succeeded, closer scrutiny always dashed such hopes. Most of Einstein's contemporaries considered the search for a unified theory to be a hopeless, if not misguided, quest.In contrast, the primary concern of theoretical physicists from the 1920s onward was quantum mechanics—the emerging framework for describing atomic and subatomic processes. Particles at these scales have such tiny masses that gravity is essentially irrelevant in their interactions, and so for decades quantum mechanical calculations generally ignored relativistic effects. Instead, by the late 1960s the focus was on a different force—the strong force, which binds together the protons and neutrons within atomic nuclei. Gabriele Veneziano, a young theorist working at the European Organization for Nuclear Research (CERN), contributed a key breakthrough in 1968 with his realization that a 200-year-old formula, the Euler beta function, was capable of explaining much of the data on the strong force then being collected at various particle accelerators around the world. A few years later, three physicists—Leonard Susskind of Stanford University, Holger Nielsen of the Niels Bohr Institute, and Yoichiro Nambu of the University of Chicago—significantly amplified Veneziano's insight by showing that the mathematics underlying his proposal described the vibrational motion of minuscule filaments of energy that resemble tiny strands of string, inspiring the name string theory. Roughly speaking, the theory suggested that the strong force amounted to strings tethering together particles attached to the strings' endpoints.

Predictions and theoretical difficulties

String theory was an intuitively attractive proposal, but by the mid-1970s more-refined measurements of the strong force had deviated from its predictions, leading most researchers to conclude that string theory had no relevance to the physical universe, no matter how elegant the mathematical theory. Nevertheless, a small number of physicists continued to pursue string theory. In 1974 John Schwarz of the California Institute of Technology and Joel Scherk of the École Normale Supérieure and, independently, Tamiaki Yoneya of Hokkaido University came to a radical conclusion. They suggested that one of the supposedly failed predictions of string theory—the existence of a particular massless particle that no experiment studying the strong force had ever encountered—was actually evidence of the very unification Einstein had anticipated.Although no one had succeeded in merging general relativity and quantum mechanics, preliminary work had established that such a union would require precisely the massless particle predicted by string theory. A few physicists argued that string theory, by having this particle built into its fundamental structure, had united the laws of the large (general relativity) and the laws of the small (quantum mechanics). Rather than merely being a description of the strong force, these physicists contended, string theory required reinterpretation as a critical step toward Einstein's unified theory.

The announcement was universally ignored. String theory had already failed in its first incarnation as a description of the strong force, and many felt it was unlikely that it would now prevail as the solution to an even more difficult problem. This view was bolstered by string theory's suffering from its own theoretical problems. For one, some of its equations showed signs of being inconsistent; for another, the mathematics of the theory demanded the universe have not just the three spatial dimensions of common experience but six others (for a total of nine spatial dimensions, or a total of ten space-time dimensions).

Dimensions and vibrations

Because of these obstacles, the number of physicists working on the theory had dropped to two—Schwarz and Michael Green, of Queen Mary College, London—by the mid-1980s. But in 1984 these two die-hard string theorists achieved a major breakthrough. Through a remarkable calculation, they proved that the equations of string theory were consistent after all. By the time word of this result had spread throughout the physics community, hundreds of researchers had dropped what they were working on and turned their full attention to string theory.Within a few months, string theory's unified framework took shape. Much as different vibrational patterns of a violin string play different musical notes, the different vibrations of the tiny strands in string theory were imagined to yield different particles of nature. According to the theory, the strings are so small that they appear to be points—as particles had long been thought to be—but in reality they have length (about 10-33 cm); the mass and charge of a particle is determined by how a string vibrates. For example, string theory posits that an electron is a string undergoing one particular vibrational pattern; a quark is imagined as a string undergoing a different vibrational pattern. Crucially, among the vibrational patterns, physicists argued, would also be the particles found by experiment to communicate nature's forces. Thus, string theory was proposed as the sought-for unification of all forces and all matter.

What of the six extra spatial dimensions required by string theory? Following a suggestion made in the 1920s by Theodor Kaluza of Germany and Oskar Klein of Sweden, string theorists envisioned that dimensions come in two distinct varieties. Like the unfurled length of a long garden hose, dimensions can be big and easy to see. But like the shorter, circular girth of the garden hose, dimensions can also be far smaller and more difficult to detect. This becomes more apparent by imagining that the circular cross section of the garden hose is shrunk ever smaller, below what can be seen with the naked eye, thereby misleading a casual observer into thinking the garden hose has only one dimension, its length. Similarly, according to string theory, the three dimensions of common experience are large and hence manifest, while the other six dimensions are crumpled so small that they have so far evaded detection.

During the decade from 1984 to 1994, many theoretical physicists strove to fulfill string theory's promise by developing this abstract, wholly mathematical framework into a concrete, predictive theory of nature. Because the infinitesimal size of strings has precluded their direct detection, theorists have sought to extract indirect implications of the theory that might be testable. In this regard, the extra dimensions of string theory have proved a major hurdle. Imagining these extra dimensions as small and hidden is a reasonable explanation for their apparent absence. However, also because strings are so small, they would vibrate in every dimension, not just in the usual three dimensions. Studies showed that, much as the shape and size of a French horn affect the vibrational patterns of airstreams coursing through the instrument, the exact shape and size of the extra dimensions would affect how strings vibrate. And since the strings' vibrations determine quantities such as particle masses and charges, predictivity requires knowledge of the geometrical form of the extra dimensions. Unfortunately, the equations of string theory allow the extra dimensions to take many different geometric forms, making it difficult to extract definitive testable predictions.

M-theory

By the mid-1990s, these and other obstacles were again eroding the ranks of string theorists. But in 1995 another breakthrough reinvigorated the field. Edward Witten of the Institute for Advanced Study, building on contributions of many other physicists, proposed a new set of techniques that refined the approximate equations on which all work in string theory had so far been based. These techniques helped reveal a number of new features of string theory. Most dramatically, these more exact equations showed that string theory has not six but seven extra spatial dimensions; the more exact equations also revealed ingredients in string theory besides strings—membranelike objects of various dimensions, collectively called branes. Finally, the new techniques established that various versions of string theory developed over the preceding decades were essentially all the same. Theorists call this unification of formerly distinct string theories by a new name, M-theory, with the meaning of M being deferred until the theory is more fully understood.Today, the understanding of many facets of string theory is still in its formative stage. Researchers recognize that, although remarkable progress has been made over the past three decades, collectively the work is burdened by its piecemeal development, with incremental discoveries having been joined like pieces of a jigsaw puzzle. That the pieces fit coherently is impressive, but the larger picture they are filling out—the fundamental principle underlying the theory—remains mysterious. Equally pressing, the theory has yet to be supported by observations and hence remains a totally theoretical construct.

In the next decade this could change. An intriguing outcome of theoretical developments since 1995 is the recognition that strings and the extra dimensions might be significantly larger than previously thought. Rather than being 10-33 cm, studies with the more refined M-theory framework have established that strings could be larger by many orders of magnitude. If so, the next generation of particle accelerators (such as the Large Hadron Collider at CERN) may have enough energy to probe the physical properties of strings directly, providing the long-sought experimental confirmation of the theory.

Supersymmetry and cosmological signatures

The experiments at CERN will also search for evidence of supersymmetry, a mathematical property discovered within string theory that requires every known particle species to have a partner particle species, called superpartners. (This property accounts for string theory often being referred to as superstring theory.) As yet, no superpartner particles have been detected, 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 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.