Is the string theory called the theory of everythings?

Answer 1

no, it evolved from "silly string".

Answer 2

i asked a similar question, and this is the answer i chose as Best: "String Theory is the assertion that the basic building block of everything in the universe is not a particle, but a string. These strings resonate at specific frequencies and it is the reflection of their resonating that we see as the different particles, e.g. electrons, photons, protons, etc. These strings are stretched throughout the entire universe and its various dimensions.

Don't worry if it doesn't make much sense. It's a very strange concept. Think of a guitar. When you hold your finger down on a fret and pluck a string, you get a note. Then, when you move your finger up or down the fretboard and pluck, you get a different note. Each different note is a different particle in the universe.

The reason the string theory exists is to explain certain phenomena that happens at the subatomic level. It is also an attempt to unify all phenomena in the universe through one theory. The idea is that if these strings represent particles, then they must also show how gravity works, and how electromagnetic forces work, among other things.

There is a fatal problem with string theory, however. It is not technically a theory. It is a hypothesis. There are no experiments to determine whether it exists. It is not falsifiable, meaning that there are no logical counterexamples. And example of falsifiability: if I make the claim that "all sharks live in the ocean," you could prove me wrong by producing a shark that does not live in the ocean. Even though such a creature may not exist, just the possibility that it could exist and be produced as tangible evidence allows my claim to be tested, which in turn makes it a proper scientific theory. On the other side of this, the "theory" of intelligent design is not a theory as it is not falsifiable. There is no experiment that could be conceived to test it. " Credits Thanks to Abulafia24

Answer 3

String theory is old hat, M or membrane theory is the new holy grail. It is basically string theory with an 11 th dimension added which solved the problem of string theory's 5 different versions by showing they could be reduced to the same equasions with the 11 th dimension added. It is thought to be the theory of everything because it can answer questions about what happeed before the big bang and what caused the big bang.

Answer 4

The Theory of Everything is basically the holy grail of physics. Physicists are searching for an underlying theory to universally explain all physics. The String Theory is the main candidate that may one day become accepted as the theory of everything.

Answer 5

I like smoking's use of a best answer, which is quite valid. I'd like to add just a few more observations regarding string/M theory.

First, it assumes an infinitely thin, Plank length string. In other words, it is one dimensional in our observable world.

Second, not to worry, because strings, in the models, actually exist in up to seven more dimensions. In other words, its substance is eight dimensional, including time.

Third, some strings are anchored in the fabric of space; others are not because they are donut shaped. The donuts, because they are not stuck into whatever the fabric of space might be, can travel between universes. (Who knows what's in between these parallel universes.)

Fourth, the major reason strings (with one dimension in our space) were invented is to get around the singularities found when assuming points in the relativistic equations. Points have zero size. So rather than assuming the "points" had a finite diameter of, say, one Plank length, they went to strings...why? Could it be that string equations are easier to solve?

Fifth, speaking of solving equations...even the string equations are difficult to solve. In fact, no one has yet solved the complete equations. Instead they use perturbations, which is to say, approximations to the full equations to solve.

Finally, as smoking's cite pointed out, string theory is not a valid theory because, up to this point, it cannot be tested. At best it is a hypothesis, at worst it is simply a WAG...mathematics seeking some physics.

Answer 6

It's a proposed method to integrate quantum theory (very small objects) and relatively (large and fast things). I think the goal is a theory of everything, but I don't think it's there yet.

Answer 7

the string theory doesn't work....too many different solutions !!

Answer 8

String theory is a model of fundamental physics whose building blocks are one-dimensional extended objects (strings) rather than the zero-dimensional points (particles) that are the basis of the Standard Model of particle physics. String theorists are attempting to adjust the Standard Model by removing the assumption in quantum mechanics that particles are point-like. By removing this assumption and replacing the point-like particles with strings, it is hoped that string theory will develop into a sensible quantum theory of gravity. Moreover, string theory appears to be able to "unify" the known natural forces (gravitational, electromagnetic, weak and strong) by describing them with the same set of equations.

No experimental verification or falsification of the theory has yet been possible, thus leading many experts to turn to one of several alternate models, such as Loop quantum gravity. However, with the construction of the Large Hadron Collider near Geneva, Switzerland scientists may produce relevant data.

Studies of string theory have revealed that it predicts not just strings, but also higher-dimensional objects (branes). String theory strongly suggests the existence of ten or eleven (in M-theory) spacetime dimensions, as opposed to the relativistic four (three spatial and one time).[1]

Overview
The basic idea behind all string theories is that the fundamental constituents of reality are strings of extremely small scale (possibly Planck length, about 10−35 m) which vibrate at specific resonant frequencies.[2] Thus, any particle should be thought of as a tiny vibrating object, rather than as a point. This object can vibrate in different modes (just as a guitar string can produce different notes), with every mode appearing as a different particle (electron, photon etc.). Strings can split and combine, which would appear as particles emitting and absorbing other particles, presumably giving rise to the known interactions between particles.

In addition to strings, string theories also include objects of higher dimensions, such as D-branes and NS-branes. Furthermore, all string theories predict the existence of degrees of freedom which are usually described as extra dimensions. String theory is thought to include some 10, 11 or 26 dimensions, depending on the specific theory and on the point of view.

Interest in string theory is driven largely by the hope that it will prove to be a consistent theory of quantum gravity or even a theory of everything. It can also naturally describe interactions similar to electromagnetism and the other forces of nature. Superstring theories include fermions, the building blocks of matter, and incorporate supersymmetry, a conjectured (but unobserved) symmetry of nature. It is not yet known whether string theory will be able to describe a universe with the precise collection of forces and particles that is observed, nor how much freedom the theory allows to choose those details.

String theory as a whole has not yet made falsifiable predictions that would allow it to be experimentally tested, though various planned observations and experiments could confirm some essential aspects of the theory, such as supersymmetry and extra dimensions. In addition, the full theory is not yet understood. For example, the theory does not yet have a satisfactory definition outside of perturbation theory; the quantum mechanics of branes (higher dimensional objects than strings) is not understood; the behavior of string theory in cosmological settings (time-dependent backgrounds) is still being worked out; finally, the principle by which string theory selects its vacuum state is a hotly contested topic (see string theory landscape).

String theory is thought to be a certain limit of another, more profound theory - M-theory - which is only partly defined and is not well understood.

A key consequence of the theory is that there is no obvious operational way to probe distances shorter than the string length

Basic properties
String theory is formulated in terms of an action principle, either the Nambu-Goto action or the Polyakov action, which describes how strings move through space and time. Like springs, the strings want to contract to minimize their potential energy, but conservation of energy prevents them from disappearing, and instead they oscillate. By applying the ideas of quantum mechanics to strings it is possible to deduce the different vibrational modes of strings, and that each vibrational state appears to be a different particle. The mass of each particle, and the fashion with which it can interact, are determined by the way the string vibrates — the string can vibrate in many different modes, just like a guitar string can produce different notes. The different modes, each corresponding to a different kind of particle, make up the "spectrum" of the theory. Strings can split and combine, which would appear as particles emitting and absorbing other particles, presumably giving rise to the known interactions between particles.

String theory includes both open strings, which have two distinct endpoints, and closed strings, where the endpoints are joined to make a complete loop. The two types of string behave in slightly different ways, yielding two different spectra. For example, in most string theories, one of the closed string modes is the graviton, and one of the open string modes is the photon. Because the two ends of an open string can always meet and connect, forming a closed string, there are no string theories without closed strings.

The earliest string model - the bosonic string, which incorporated only bosons, describes - in low enough energies - a quantum gravity theory, which also includes (if open strings are incorporated as well) gauge fields such as the photon (or, more generally, any Yang-Mills theory). However, this model has problems. Most importantly, the theory has a fundamental instability, believed to result in the decay (at least partially) of space-time itself. Additionally, as the name implies, the spectrum of particles contains only bosons, particles which, like the photon, obey particular rules of behavior. Roughly speaking, bosons are the constituents of radiation, but not of matter, which is made of fermions. Investigating how a string theory may include fermions in its spectrum led to the invention of supersymmetry, a mathematical relation between bosons and fermions. String theories which include fermionic vibrations are now known as superstring theories; several different kinds have been described, but all are now thought to be different limits of one theory (the M-theory).

While understanding the details of string and superstring theories requires considerable mathematical sophistication, some qualitative properties of quantum strings can be understood in a fairly intuitive fashion. For example, quantum strings have tension, much like regular strings made of twine; this tension is considered a fundamental parameter of the theory. The tension of a quantum string is closely related to its size. Consider a closed loop of string, left to move through space without external forces. Its tension will tend to contract it into a smaller and smaller loop. Classical intuition suggests that it might shrink to a single point, but this would violate Heisenberg's uncertainty principle. The characteristic size of the string loop will be a balance between the tension force, acting to make it small, and the uncertainty effect, which keeps it "stretched". Consequently, the minimum size of a string is related to the string tension.

[edit] Dualities
Before the "duality revolution" there were believed to be five distinct versions of string theory, plus the (unstable) bosonic and gluonic theories.

String Theories
Type Spacetime dimensions
Details
Bosonic 26 Only bosons, no fermions means only forces, no matter, with both open and closed strings; major flaw: a particle with imaginary mass, called the tachyon, representing an instability in the theory.
I 10 Supersymmetry between forces and matter, with both open and closed strings, no tachyon, group symmetry is SO(32)
IIA 10 Supersymmetry between forces and matter, with closed strings and open strings bound to D-branes, no tachyon, massless fermions spin both ways (nonchiral)
IIB 10 Supersymmetry between forces and matter, with closed strings and open strings bound to D-branes, no tachyon, massless fermions only spin one way (chiral)
HO 10 Supersymmetry between forces and matter, with closed strings only, no tachyon, heterotic, meaning right moving and left moving strings differ, group symmetry is SO(32)
HE 10 Supersymmetry between forces and matter, with closed strings only, no tachyon, heterotic, meaning right moving and left moving strings differ, group symmetry is E8×E8

Note that in the type IIA and type IIB string theories closed strings are allowed to move everywhere throughout the ten-dimensional space-time (called the bulk), while open strings have their ends attached to D-branes, which are membranes of lower dimensionality (their dimension is odd - 1,3,5,7 or 9 - in type IIA and even - 0,2,4,6 or 8 - in type IIB, including the time direction).

Before the 1990s, string theorists believed there were five distinct superstring theories: type I, types IIA and IIB, and the two heterotic string theories (SO(32) and E8×E8). The thinking was that out of these five candidate theories, only one was the actual correct theory of everything, and that theory was the theory whose low energy limit, with ten dimensions spacetime compactified down to four, matched the physics observed in our world today. It is now known that this picture was naive, and that the five superstring theories are connected to one another as if they are each a special case of some more fundamental theory. These theories are related by transformations that are called dualities. If two theories are related by a duality transformation, it means that the first theory can be transformed in some way so that it ends up looking just like the second theory. The two theories are then said to be dual to one another under that kind of transformation. Put differently, the two theories are two mathematically different descriptions of the same phenomena.

These dualities link quantities that were also thought to be separate. Large and small distance scales, strong and weak coupling strengths – these quantities have always marked very distinct limits of behavior of a physical system, in both classical field theory and quantum particle physics. But strings can obscure the difference between large and small, strong and weak, and this is how these five very different theories end up being related.