Editing Theory of everything (section)

===Antiquity to 19th century===
Many ancient cultures such as [[Babylonian astronomers]] and [[Indian astronomy]] studied the pattern of the ''Seven Sacred Luminaires''/[[Classical Planets]] against the background of [[stars]], with their interest being to relate celestial movement to human events ([[astrology]]), and the goal being to predict events by recording events against a time measure and then look for recurrent patterns. The debate between the universe having either [[Temporal finitism|a beginning]] or [[Cyclic model|eternal cycles]] can be traced to ancient [[Babylonia]].<ref name="Hodge">{{cite book |last1=Hodge |first1=John C. |title=Theory of Everything: Scalar Potential Model of the Big and the Small |date=2012 |isbn=978-1-4699-8736-1 |pages=1–13, 99 |publisher=CreateSpace Independent Publishing Platform }}</ref> [[Hindu cosmology]] posits that time is infinite with a ''cyclic universe'', where the current universe was preceded and will be followed by an infinite number of universes.<ref>{{cite book |author=Sushil Mittal |author2=Gene Thursby |page=284 |title=Hindu World |publisher=Routledge |year=2012 |isbn=978-1-134-60875-1}}</ref><ref>{{cite book |author=Jones |first=Andrew Zimmerman |title=String Theory For Dummies |publisher=John Wiley & Sons |year=2009 |isbn=978-0-470-59584-8 |page=262}}</ref> Time scales mentioned in [[Hindu cosmology]] correspond to those of modern scientific cosmology. Its cycles run from an ordinary day and night to a day and night of Brahma, 8.64 billion years long.<ref>{{cite book |author=Sagan, Carl |title=Cosmos |year=2006 }}</ref>

The [[natural philosophy]] of [[atomism]] appeared in several ancient traditions. In ancient [[Greek philosophy]], the [[Pre-Socratic philosophy|pre-Socratic philosophers]] speculated that the apparent diversity of observed phenomena was due to a single type of interaction, namely the motions and collisions of atoms. The concept of 'atom' proposed by [[Democritus]] was an early philosophical attempt to unify phenomena observed in nature. The concept of 'atom' also appeared in the [[Nyaya]]-[[Vaisheshika]] school of ancient [[Indian philosophy]].

[[Archimedes]] was possibly the first philosopher to have described nature with axioms (or principles) and then deduce new results from them. Any "theory of everything" is similarly expected to be based on axioms and to deduce all observable phenomena from them.<ref name="Impey2012" />{{rp|340}}

Following earlier atomistic thought, the [[mechanical philosophy]] of the 17th century posited that all forces could be ultimately reduced to [[contact force]]s between the atoms, then imagined as tiny solid particles.<ref name="Burns2001">{{cite book |author=Burns |first=William E. |title=The Scientific Revolution: An Encyclopedia |date=1 January 2001 |publisher=ABC-CLIO |isbn=978-0-87436-875-8}}</ref>{{rp|184}}<ref>
{{cite book
 |first=Steven |last=Shapin
 |date=1996
 |title=The Scientific Revolution
 |url=https://archive.org/details/scientificrevolu00shap_0 |url-access=registration |publisher=[[University of Chicago Press]]
 |isbn=978-0-226-75021-7
}}</ref>

In the late 17th century, [[Isaac Newton]]'s description of the long-distance force of gravity implied that not all forces in nature result from things coming into contact. Newton's work in his ''[[Philosophiæ Naturalis Principia Mathematica|Mathematical Principles of Natural Philosophy]]'' dealt with this in a further example of [[Unification (physics)|unification]], in this case unifying [[Galileo]]'s work on terrestrial gravity, [[Kepler]]'s laws of planetary motion and the phenomenon of [[tide]]s by explaining these apparent actions at a distance under one single law: the law of [[universal gravitation]].<ref>{{cite book |page=255 |url=https://books.google.com/books?id=6EqxPav3vIsC&pg=PA255 |title=The Mathematical Principles of Natural Philosophy |volume=II |last1=Newton |first1=Sir Isaac |date=1729}}</ref> Newton achieved the [[Unification of theories in physics#Unification of gravity and astronomy|first great unification in physics]], and he further is credited with laying the foundations of future endeavors for a grand unified theory.

In 1814, building on these results, [[Laplace]] famously suggested that a [[Laplace's demon|sufficiently powerful intellect]] could, if it knew the position and velocity of every particle at a given time, along with the laws of nature, calculate the position of any particle at any other time:<ref name="Carroll2010">{{cite book <!-- Citation bot deny--> |author=Carroll |first=Sean |title=[[From Eternity to Here: The Quest for the Ultimate Theory of Time]] |publisher=Penguin Group US |year=2010 |isbn=978-1-101-15215-7 |language=en-us}}</ref>{{rp |ch 7}}

{{quote|An intellect which at a certain moment would know all forces that set nature in motion, and all positions of all items of which nature is composed, if this intellect were also vast enough to submit these data to analysis, it would embrace in a single formula the movements of the greatest bodies of the universe and those of the tiniest atom; for such an intellect nothing would be uncertain and the future just like the past would be present before its eyes.|''Essai philosophique sur les probabilités'', Introduction. 1814}}

Laplace thus envisaged a combination of gravitation and mechanics as a theory of everything. Modern [[quantum mechanics]] implies that [[Heisenberg uncertainty|uncertainty is inescapable]], and thus that Laplace's vision has to be amended: a theory of everything must include gravitation and quantum mechanics. Even ignoring quantum mechanics, [[chaos theory]] is sufficient to guarantee that the future of any sufficiently complex mechanical or astronomical system is unpredictable.

In 1820, [[Hans Christian Ørsted]] discovered a connection between electricity and magnetism, triggering decades of work that culminated in 1865, in [[James Clerk Maxwell]]'s theory of [[electromagnetism]], which achieved the [[Unification of theories in physics#Unification of magnetism, electricity, light and related radiation|second great unification in physics]]. During the 19th and early 20th centuries, it gradually became apparent that many common examples of forces – contact forces, [[elasticity (physics)|elasticity]], [[viscosity]], [[friction]], and [[pressure]] – result from electrical interactions between the smallest particles of matter.

In his experiments of 1849–1850, [[Michael Faraday]] was the first to search for a unification of [[gravity]] with electricity and magnetism.<ref>
{{Cite journal
 |first=M.|last=Faraday
 |date=1850
 |title=Experimental Researches in Electricity. Twenty-Fourth Series. On the Possible Relation of Gravity to Electricity
 |journal=Abstracts of the Papers Communicated to the Royal Society of London
 |volume=5 |pages=994–995
 |doi=10.1098/rspl.1843.0267
|doi-access=free
 }}</ref> However, he found no connection.

In 1900, [[David Hilbert]] published a famous list of mathematical problems. In [[Hilbert's sixth problem]], he challenged researchers to find an axiomatic basis to all of physics. In this problem he thus asked for what today would be called a theory of everything.<ref>{{Cite journal |doi=10.1090/S0273-0979-2013-01439-3 |title=Hilbert's 6th Problem: Exact and approximate hydrodynamic manifolds for kinetic equations |journal=Bulletin of the American Mathematical Society |volume=51 |issue=2 |page=187 |year=2013 |last1=Gorban |first1=Alexander N. |last2=Karlin |first2=Ilya|arxiv=1310.0406 |bibcode=2013arXiv1310.0406G |s2cid=7228220 }}</ref>