Concept
Theory of everything
Overview
A theory of everything or final theory is a hypothetical coherent theoretical framework of physics containing all physical principles. The scope of the concept of a "theory of everything" varies. The original technical concept referred to unification of the four fundamental interactions: electromagnetism, strong and weak nuclear forces, and gravity.
Finding such a theory is one of the major unsolved problems in physics. Numerous popular books apply the words "theory of everything" to more expansive concepts such as predicting everything in the universe from logic alone, complete with discussions on how this is not possible.
Starting with Isaac Newton's unification of terrestrial gravity, responsible for weight, with celestial gravity, responsible for planetary orbits, concepts in fundamental physics have been successively unified. The phenomena of electricity and magnetism were combined by James Clerk Maxwell's theory of electromagnetism and Albert Einstein's theory of relativity explained how they are connected. By the 1930s, Paul Dirac combined relativity and quantum mechanics and, working with other physicists, developed quantum electrodynamics that combines quantum mechanics and electromagnetism.
Work on nuclear and particle physics led to the discovery of the strong nuclear and weak nuclear forces which were combined in the quantum field theory to implement the Standard Model of physics, a unification of all forces except gravity. The lone fundamental force not built into the Standard Model is gravity. General relativity provides a theoretical framework for understanding gravity across scales from the laboratory to planets to the complete universe, but it has not been successfully unified with quantum mechanics.
General relativity and quantum mechanics have been repeatedly validated in their separate fields of relevance. Since the usual domains of applicability of general relativity and quantum mechanics are so different, most situations require that only one of the two theories be used. The two theories are considered incompatible in regions of extremely small scale – the Planck scale – such as those that exist within a black hole or during the beginning stages of the universe (i.e., the moment immediately following the Big Bang). To resolve the incompatibility, a theoretical framework revealing a deeper underlying reality, unifying gravity with the other three interactions, must be discovered to harmoniously integrate the realms of general relativity and quantum mechanics into a seamless whole: a theory of everything may be defined as a comprehensive theory that, in principle, would be capable of describing all physical phenomena in the universe.
In pursuit of this goal, quantum gravity has become one area of active research. One example is string theory, which evolved into a candidate for the theory of everything, but not without drawbacks (most notably, its apparent lack of currently testable predictions) and controversy. String theory posits that at the beginning of the universe (up to 10−43 seconds after the Big Bang), the four fundamental forces were once a single fundamental force. According to string theory, every particle in the universe, at its most ultramicroscopic level (Planck length), consists of varying combinations of vibrating strings (or strands) with preferred patterns of vibration. String theory further claims that it is through these specific oscillatory patterns of strings that a particle of unique mass and force charge is created (that is to say, the electron is a type of string that vibrates one way, while the up quark is a type of string vibrating another way, and so forth). String theory/M-theory proposes six or seven dimensions of spacetime in addition to the four common dimensions for a ten- or eleven-dimensional spacetime.
Overview adapted from Wikipedia (CC BY-SA 4.0; see the article history for authors).
Possible passages
Found by search and not yet checked by a person; they may only mention the idea in passing.
The theory that matter consists of “atoms”, _i.e._ of little bits that cannot be divided, is due to the Greeks, but with them it was only a speculation. The evidence for what is called the atomic theory was derived from chemistry, and the theory itself, in its nineteenth-century form, was mainly due to Dalton. It was found that there were a number of “elements”, and that other substances were compounds of these…
Bertrand Russell, Philosophy
States what Theory of everything is.
At some points of its orbit it is nearer to the sun than at other points. The point where it is nearest to the sun is called its “perihelion.” Now it was found by observation that, from one occasion when Mercury is nearest to the sun until the next, Mercury does not go exactly once round the sun, but a little bit more. The discrepancy is very small; it amounts to an angle of forty-two seconds in a century. That is…
Bertrand Russell, The A B C of Relativity
States what Theory of everything is.
That if the force, which retained each of them in their orbits, was like that of gravity, and directed towards the Sun, they would, each of them, describe equal areas in equal times.
Adam Smith, The Essays of Adam Smith
Close in meaning to Theory of everything; the term itself is not named.
Related ideas
- Fundamental interaction
- Falsifiability
- General relativity
- Second law of thermodynamics
- Philosophy
- Isaac Newton
- Loop quantum gravity
- Johannes Kepler
- Archimedes
- Stephen Hawking
- Theoretical physics
- Dark energy
- Maxwell's equations
- Natural selection
- Arthur Eddington
- Pseudoscience
- Particle physics
- Photon
- Prediction
- Quark
- Quantum mechanics
- Quantum field theory
- Quantum gravity
- Roger Penrose
Place in the tradition
Part of Free will.