Everything, every-thing, or every thing is all that exists; the opposite of

nothing Nothing, the complete absence of anything, has been a matter of philosophical debate since at least the 5th century BC. Early Greek philosophers argued that it was impossible for ''nothing'' to exist. The atomists allowed ''nothing'' but only i ...

, or its complement. It is the totality of things relevant to some

subject matter Subject matter, in general, is anything which can be content for some theory. Subject matter may refer to: * Patentable subject matter (or statutory subject matter), defining whether patent protection is available * Subject-matter jurisdiction, d ...

. Without expressed or implied limits, it may refer to anything. The

universe The universe is all of space and time and their contents, including planets, stars, galaxies, and all other forms of matter and energy. The Big Bang theory is the prevailing cosmological description of the development of the universe. Acc ...

is everything that exists theoretically, though a

multiverse The multiverse is a hypothetical group of multiple universes. Together, these universes comprise everything that exists: the entirety of space, time, matter, energy, information, and the physical laws and constants that describe them. The di ...

may exist according to theoretical cosmology predictions. It may refer to an anthropocentric worldview, or the sum of human experience, history, and the human condition in general."This is the excellent foppery of the world..." —

Shakespeare William Shakespeare ( 26 April 1564 – 23 April 1616) was an English playwright, poet and actor. He is widely regarded as the greatest writer in the English language and the world's pre-eminent dramatist. He is often called England's nation ...

, ''

King Lear ''King Lear'' is a tragedy written by William Shakespeare. It is based on the mythological Leir of Britain. King Lear, in preparation for his old age, divides his power and land between two of his daughters. He becomes destitute and insane an ...

'', Every

object Object may refer to: General meanings * Object (philosophy), a thing, being, or concept ** Object (abstract), an object which does not exist at any particular time or place ** Physical object, an identifiable collection of matter * Goal, an ai ...

and

entity An entity is something that exists as itself, as a subject or as an object, actually or potentially, concretely or abstractly, physically or not. It need not be of material existence. In particular, abstractions and legal fictions are usually ...

is a part of everything, including all

physical bodies In common usage and classical mechanics, a physical object or physical body (or simply an object or body) is a collection of matter within a defined contiguous boundary in three-dimensional space. The boundary must be defined and identified by t ...

and in some cases all

abstract object In metaphysics, the distinction between abstract and concrete refers to a divide between two types of entities. Many philosophers hold that this difference has fundamental metaphysical significance. Examples of concrete objects include plants, hum ...

Scope

In ordinary conversation, ''everything'' usually refers only to the totality of things relevant to the subject matter. When there is no expressed limitation, ''everything'' may refer to the

, or the

world In its most general sense, the term "world" refers to the totality of entities, to the whole of reality or to everything that is. The nature of the world has been conceptualized differently in different fields. Some conceptions see the worl ...

. The universe is most commonly defined as everything that physically exists: the entirety of

time Time is the continued sequence of existence and events that occurs in an apparently irreversible succession from the past, through the present, into the future. It is a component quantity of various measurements used to sequence events, to ...

, all forms of

matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects that can be touched are ultimately composed of atoms, which are made up of interacting subatomic partic ...

energy In physics, energy (from Ancient Greek: ἐνέργεια, ''enérgeia'', “activity”) is the quantitative property that is transferred to a body or to a physical system, recognizable in the performance of work and in the form of heat a ...

and

momentum In Newtonian mechanics, momentum (more specifically linear momentum or translational momentum) is the product of the mass and velocity of an object. It is a vector quantity, possessing a magnitude and a direction. If is an object's mass an ...

, and the

physical law Scientific laws or laws of science are statements, based on repeated experiments or observations, that describe or predict a range of natural phenomena. The term ''law'' has diverse usage in many cases (approximate, accurate, broad, or narrow) a ...

s and

constants Constant or The Constant may refer to: Mathematics * Constant (mathematics), a non-varying value * Mathematical constant, a special number that arises naturally in mathematics, such as or Other concepts * Control variable or scientific const ...

that govern them. However, the term "universe" may be used in slightly different contextual senses, denoting such concepts as the '' cosmos'', the ''

'', or ''

nature Nature, in the broadest sense, is the physics, physical world or universe. "Nature" can refer to the phenomenon, phenomena of the physical world, and also to life in general. The study of nature is a large, if not the only, part of science. ...

''. According to some speculations, this universe may be one of many disconnected universes, which are collectively denoted as the

. In the

bubble universe theory Eternal inflation is a hypothetical inflationary universe model, which is itself an outgrowth or extension of the Big Bang theory. According to eternal inflation, the inflationary phase of the universe's expansion lasts forever throughout most ...

, there is an infinite variety of universes, each with different

physical constant A physical constant, sometimes fundamental physical constant or universal constant, is a physical quantity that is generally believed to be both universal in nature and have constant value in time. It is contrasted with a mathematical constant, ...

s. In the

many-worlds hypothesis The many-worlds interpretation (MWI) is an interpretation of quantum mechanics that asserts that the universal wavefunction is objectively real, and that there is no wave function collapse. This implies that all possible outcomes of quantum me ...

, new universes are spawned with every quantum measurement. By definition, these speculations cannot currently be tested experimentally, yet, if multiple universes do exist, they would still be part of everything. Especially in a

metaphysical Metaphysics is the branch of philosophy that studies the fundamental nature of reality, the first principles of being, identity and change, space and time, causality, necessity, and possibility. It includes questions about the nature of conscio ...

context, ''World'' may refer to everything that constitutes

reality Reality is the sum or aggregate of all that is real or existent within a system, as opposed to that which is only imaginary. The term is also used to refer to the ontological status of things, indicating their existence. In physical terms, r ...

and the

: see World (philosophy). However, world may only refer to ''

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...

'' envisioned from an anthropocentric or

human Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, culture, ...

worldview, as a place by human beings.

In theoretical physics

theoretical physics Theoretical physics is a branch of physics that employs mathematical models and abstractions of physical objects and systems to rationalize, explain and predict natural phenomena. This is in contrast to experimental physics, which uses experim ...

, a ''theory of everything'' (TOE) is a hypothetical

theory A theory is a rational type of abstract thinking about a phenomenon, or the results of such thinking. The process of contemplative and rational thinking is often associated with such processes as observational study or research. Theories may be s ...

that fully explains and links together all known physical phenomena. Initially, the term was used with an ironic connotation to refer to various overgeneralized theories. For example, a great-grandfather of Ijon Tichy—a character from a cycle of Stanisław Lem's

science fiction Science fiction (sometimes shortened to Sci-Fi or SF) is a genre of speculative fiction which typically deals with imaginative and futuristic concepts such as advanced science and technology, space exploration, time travel, parallel unive ...

stories of the 1960s—was known to work on the "General Theory of Everything". Over time, the term stuck in popularizations of

quantum physics Quantum mechanics is a fundamental theory in physics that provides a description of the physical properties of nature at the scale of atoms and subatomic particles. It is the foundation of all quantum physics including quantum chemistry, qua ...

to describe a theory that would unify or explain through a single model the theories of all fundamental interactions of nature. There have been many theories of everything proposed by theoretical physicists over the last century, but none have been confirmed experimentally. The primary problem in producing a TOE is that the accepted theories of

quantum mechanics Quantum mechanics is a fundamental theory in physics that provides a description of the physical properties of nature at the scale of atoms and subatomic particles. It is the foundation of all quantum physics including quantum chemistry, ...

general relativity General relativity, also known as the general theory of relativity and Einstein's theory of gravity, is the geometric theory of gravitation published by Albert Einstein in 1915 and is the current description of gravitation in modern physics ...

, or

special relativity In physics, the special theory of relativity, or special relativity for short, is a scientific theory regarding the relationship between space and time. In Albert Einstein's original treatment, the theory is based on two postulates: # The laws o ...

are hard to combine. Theories exploring quantum mechanics and string theory are easier to combine. Based on theoretical

holographic principle The holographic principle is an axiom in string theories and a supposed property of quantum gravity that states that the description of a volume of space can be thought of as encoded on a lower-dimensional boundary to the region — such as a ...

arguments from the 1990s, many physicists believe that 11-dimensional

M-theory M-theory is a theory in physics that unifies all consistent versions of superstring theory. Edward Witten first conjectured the existence of such a theory at a string theory conference at the University of Southern California in 1995. Witten's ...

, which is described in many sectors by

matrix string theory In physics, matrix string theory is a set of equations that describe superstring theory in a non-perturbative framework. Type IIA string theory can be shown to be equivalent to a maximally supersymmetric two-dimensional gauge theory, the gauge ...

, and in many other sectors by perturbative string theory, is the complete theory of everything. Other physicists disagree.

In philosophy

In philosophy, a ''theory of everything'' or ''TOE'' is an ultimate, all-encompassing explanation of

.Rescher, Nicholas (2006a). "Holistic Explanation and the Idea of a Grand Unified Theory". Collected Papers IX: Studies in Metaphilosophy.Rescher, Nicholas (2006b). "The Price of an Ultimate Theory". Collected Papers IX: Studies in Metaphilosophy.Walker, Mark Alan (March 2002)
"Prolegomena to Any Future Philosophy"
Journal of Evolution and Technology Vol. 10. Adopting the term from physics, where the search for a theory of everything is ongoing, philosophers have discussed the viability of the concept and analyzed its properties and implications. Among the questions to be addressed by a

philosophical theory A philosophical theory or philosophical position''Dictionary of Theories'', Jennifer Bothamley is a view that attempts to explain or account for a particular problem in philosophy. The use of the term "theory" is a statement of colloquial English ...

of everything are: "Why is reality understandable?", "Why are the laws of nature as they are?", and " Why is there anything at all?".

References

{{reflist Perception Ontology Quantity

Scope

In theoretical physics

In philosophy

See also

References