Editing Digital physics

{{short description|The idea that the universe is a digital computation device}}
{{Distinguish|Computational physics|Computational philosophy}}
'''Digital physics''' is a speculative idea suggesting that the [[universe]] can be conceived of as a vast, digital computation device, or as the output of a [[deterministic]] or [[probabilistic]] [[computer program]].<ref name=":0">{{Citation |last= Schmidhuber |first=Jürgen |title=A computer scientist's view of life, the universe, and everything |date=1997 |url= https://doi.org/10.1007/BFb0052088 |work= Foundations of Computer Science: Potential — Theory — Cognition |series= Lecture Notes in Computer Science |volume= 1337 |pages= 201–208 |editor-last= Freksa |editor-first= Christian |place= Berlin, Heidelberg |publisher= Springer |language= en |doi= 10.1007/bfb0052088 |isbn= 978-3-540-69640-7 |s2cid= 17830241 |access-date= 2022-05-23 |editor2-last= Jantzen |editor2-first= Matthias |editor3-last= Valk |editor3-first= Rüdiger |arxiv= quant-ph/9904050 }}</ref> The hypothesis that the universe is a [[digital computer]] was proposed by [[Konrad Zuse]] in his 1969 book ''[[Rechnender Raum]]''<ref>{{Cite web |title=Das Jahr des rechnenden Raums |url= https://blog.hnf.de/das-jahr-des-rechnenden-raums/ |access-date=2022-05-23 |website=blog.hnf.de |language=de}}</ref> (''Calculating-space'').<ref>{{Cite book |last= Zuse |first= Konrad |title= Rechnender Raum |date= 1969 |publisher=[[Springer Vieweg]] |isbn= 978-3-663-02723-2 |location= Braunschweig}}</ref> The term "digital physics" was coined in 1978 by [[Edward Fredkin]],<ref>[http://simson.net/ref/1978/6.895%20Digital%20Physics/1978-01-17%20Digital%20Physics%20Lecture%20Outline.pdf 6.895 Digital Physics Lecture Outline], MIT Course Catalog Listing, 1978 (PDF)</ref> who later came to prefer the term "'''digital philosophy'''".<ref>{{Cite web |archivedate=2021-01-26 |title= Digital Philosophy {{!}} A New Way of Thinking About Physics |url=http://www.digitalphilosophy.org/ |archiveurl= https://web.archive.org/web/20210126115736/http://www.digitalphilosophy.org/ |website=digitalphilosophy.org}}</ref> Fredkin taught a graduate course called "digital physics" at MIT in 1978, and collaborated with [[Tommaso Toffoli]] on "conservative logic" while [[Norman Margolus]] served as a graduate student in his research group.<ref>{{Cite web |title=Tomorrow’s computer, yesterday |url=https://www.technologyreview.com/2021/04/27/1021714/tomorrows-computer-yesterday/ |access-date=2025-04-07 |website=MIT Technology Review |language=en}}</ref>

''Digital physics'' posits that there exists, at least in principle, a [[computer program|program]] for a [[universal computer]] that computes the [[Cosmic evolution|evolution]] of the [[universe]]. The computer could be, for example, a huge [[cellular automaton]].<ref name=":0" /><ref>Zuse, Konrad, 1967, Elektronische Datenverarbeitung vol 8., pages 336–344</ref> It is deeply connected to the concept of [[information theory]], particularly the idea that the universe's fundamental building blocks might be bits of information rather than traditional particles or fields.  

However, extant models of digital physics face challenges, particularly in reconciling with several continuous [[symmetry in physics|symmetries]]<ref>{{Cite journal|last= Fritz|first= Tobias|date= June 2013|title= Velocity polytopes of periodic graphs and a no-go theorem for digital physics|journal= Discrete Mathematics|language= en|volume= 313|issue= 12|pages= 1289–1301|doi= 10.1016/j.disc.2013.02.010|doi-access= free|arxiv= 1109.1963}}</ref> in physical laws, e.g., [[rotational symmetry]], [[translational symmetry]], [[Lorentz symmetry]], and the [[Lie group]] gauge invariance of [[Yang–Mills theory|Yang–Mills theories]], all of which are central to current physical theories. Moreover, existing models of digital physics violate various well-established features of [[quantum physics]], as they belong to a class of theories involving local [[hidden variable theory|hidden variables]]. These models have so far been disqualified experimentally by physicists using [[Bell's theorem]].<ref>{{Cite journal |last= Aaronson |first= Scott |date= 2014 |title= Quantum randomness: if there's no predeterminism in quantum mechanics, can it output numbers that truly have no pattern? |url= https://link.gale.com/apps/doc/A373474677/AONE?u=mlin_oweb&sid=googleScholar&xid=62475a52 |journal= American Scientist |volume= 102 |issue= 4 |pages= 266–271|doi= 10.1511/2014.109.266 |doi-access= free }}</ref><ref>{{Cite book |doi = 10.1007/978-3-319-74971-6_8
|title = Quantum Foundations, Probability and Information |year = 2018 |last1 = Jaeger |first1 = Gregg | chapter= Clockwork Rebooted: Is the Universe a Computer? | series=STEAM-H: Science, Technology, Engineering, Agriculture, Mathematics & Health |pages = 71–91| isbn=978-3-319-74970-9 }}</ref>

== See also ==
* [[Mathematical universe hypothesis]]
* [[It from bit]]
* [[Simulation hypothesis]]
* [[Weyl's tile argument]]
* ''[[Natura non facit saltus]]''

==References==
{{reflist|35em}}

==Further reading==
* Robert Wright, [https://robertwright.com/universe-just-happen/ "Did the Universe Just Happen?"], ''Atlantic Monthly'', April 1988 - Article discussing Fredkin and his digital physics ideas

[[Category:Theory of computation]]

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