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{{Short description|Philosophical view that there is no correct way of perceiving the passage of time}}
'''Eternalism''' is a ] approach to the ] nature of ], which takes the view that all points in time are equally "real" (they all have the same ontological status), as opposed to the ] idea that only the present is real.<ref>{{Cite book|title=General Philosophy of Science: Focal Issues |first=Theo A.F.|last=Kuipers|publisher=North Holland|year=2007|isbn=978-0-444-51548-3|page=326|url=http://books.google.com/books?id=qUMuFaXjNjEC&lpg=PP1&pg=PA326#v=onepage&q&f=false}}</ref> This would mean that ] events are "already there", and that there is no ] flow of time. Modern advocates often take inspiration from the ], with some such as ] invoking ], which says that the question of whether two events occur at the same time is not absolute, but depends on the observer's reference frame. Some also take inspiration from the way that the mathematical formulation of relativity treats time as a single dimension in a four-dimensional ].<ref>{{Citation | last1 = Peterson | first1 = Daniel | last2 = Silberstein | first2 = Michael | editor-last = Petkov | editor-first = Vesselin | contribution = Relativity of Simultaneity and Eternalism: In Defense of the Block Universe | year = 2009 | url = http://books.google.com/books?id=t35AR6-F5QQC&lpg=PP1&pg=PA208#v=onepage&q&f=false | title = Space, Time, and Spacetime: Physical and Philosophical Implications of Minkowski's Unification of Space and Time | page = 208}}</ref> However, the philosophical proposal dates back at least to ] ], first published in '']'' in 1908, only three years after the first paper on relativity. Eternalism, defined as the view that there are no ontological differences between past, present and future, is also known as the "'''block universe'''" theory<ref name="Dowden2001">{{cite web |first=Bradley |last=Dowden |year=2001 |title=Time |url=http://www.iep.utm.edu/time/ |accessdate=25 July 2012|quote=The third and more popular theory is that there are no significant ontological differences among present, past, and future because the differences are merely subjective. This view is called “the block universe theory” or “eternalism.”}}</ref><ref name="Dowden2009">{{cite book |first=Bradley |last=Dowden |year=2009 |title=The Metaphysics of Time: A Dialogue |series=New Dialogues in Philosophy |publisher=Rowman & Littlefield |isbn=9780742560314 |lccn=2009021319 |url=http://books.google.com/books?id=PPkwb6XsvOwC&pg=PA149 |page=149 |quote=Block universe theory: Metaphysical theory that implies all of the past, present, and future is real. The name derives from the fact that a Minkowski diagram would represent events as points in a block if space and time were to be finite in all directions. Also called "eternalism."}}</ref><ref>{{cite book|first=Dennis |last=Dieks |year=2008 |title=The Ontology of Spacetime II |url=http://books.google.com/books?id=Ov6zaiANlgsC&lpg=PP1&pg=PA229#v=onepage&q&f=false |page=229 |quote=It is commonly held that relativity favors the "block universe" view (known also as "eternalism"), according to which all events enjoy the same ontological status regardless of their location}}</ref><ref>{{cite book|first=Michael |last=Rea|year=2009 |title=Arguing About Metaphysics |url=http://books.google.com/books?id=yzZRAAAAYAAJ&q=eternalism+same+%22block+universe%22#search_anchor |page=223 |quote=It does not help, either, that there is a tendency to conflate eternalism — the four-dimensional "block universe" view — with causal determinism.}}</ref> (the term '''"block time"''' is also used, with some authors treating it as interchangeable with "block universe"<ref name="Carroll2010">{{cite book |first=S.M. |last=Carroll |year=2010 |title=From Eternity to Here: The Quest for the Ultimate Theory of Time |publisher=Dutton |isbn=9780525951339 |lccn=2009023828 |url=http://books.google.com/books?id=Uak1wtcXrjwC&pg=PT39 |page=39 |quote=In the philosophic literature, this is sometimes called the "block time" or "block universe" perspective, thinking of all space and time as a single existing block of spacetime. For our present purposes, the important point is that we ''can'' think about time in this way. Rather than carrying a picture in the back of our minds in which times is a substance that flows around us or through which we move, we can think of an ordered sequence of correlated events, together constituting the entire universe. Time is then something we reconstruct from the correlations in these events.}}</ref>, and some<ref>{{cite book |first=J.J.A. |last=Mooij |year=2005 |title=Time and Mind: The History of a Philosophical Problem |publisher=Brill Academic Pub |isbn=9789004141520 |url=http://books.google.com/books?id=cTEKAQAAMAAJ&q=%22block+universe%22+%22block+time%22#search_anchor |page=224 |quote=This four-dimensional manifold was assigned the name 'block universe'. Its temporal dimension, block time, was the objective counterpart of the ongoing and passing time that people experience internally.}}</ref> defining it specifically as the temporal dimension of the block universe) due to its description of ] as an unchanging four-dimensional "block"<ref>"Block" here refers to the idea of spacetime as something fixed and unchanging, like a solid block, and not to the actual geometric shape of space or spacetime.</ref> (the name is inspired by the depiction of spacetime in the ]s used in ])<ref name="Dowden2009" />,<ref> as opposed to the view of the world as a three-dimensional space modulated by the passage of time.


]
==Problems with the flow of time==


In the ], '''eternalism'''<ref>{{cite journal |last1=Le Bihan |first1=Baptiste |title=String theory, loop quantum gravity and eternalism |journal=European Journal for Philosophy of Science |date=2020 |volume=10 |issue=2 |pages=17 |arxiv=2005.09335 |doi=10.1007/s13194-020-0275-3|s2cid=210958803 }}</ref> is an approach to the ] nature of ], which takes the view that all existence in time is equally ''real'', as opposed to ] or the ] theory of time, in which at least the future is not the same as any other time.<ref>{{Cite book|title=General Philosophy of Science: Focal Issues |first=Theo A.F.|last=Kuipers|publisher=North Holland|year=2007|isbn=978-0-444-51548-3|page=326|url=https://books.google.com/books?id=qUMuFaXjNjEC&pg=PA326}}</ref> Some forms of eternalism give time a similar ] to that of ], as a ], with different times being as real as different places, and ] events are "already there" in the same sense other places are already there, and that there is no ] flow of time.<ref>{{citation|author=Tim Maudlin|author-link=Tim Maudlin|title=The Metaphysics Within Physics|isbn=9780199575374|year=2010|chapter=On the Passing of Time|publisher=Oxford University Press }}</ref>
Conventionally, time is divided into three distinct regions; the "]", the "present", and the "]". Using that representational model, the past is generally seen as being immutably fixed, and the future as undefined and nebulous. As time passes, the moment that was once the present becomes part of the past; and part of the future, in turn, becomes the new present. In this way time is said to pass, with a distinct present moment "moving" forward into the future and leaving the past behind. This view of time is given the name ] by philosophers.


It is sometimes referred to as the "'''block time'''" or "'''block universe'''" theory due to its description of ] as an unchanging four-dimensional "block", as opposed to the view of the world as a three-dimensional space modulated by the passage of time.
This conventional model presents a number of difficult philosophical problems, and seems difficult to reconcile with currently accepted scientific theories such as the ].


===Simultaneity=== ==The present==
] has shown that the concept of ] is not universal: observers in different ] can have different perceptions of whether a given pair of events happened at the same time or at different times, with there being no physical basis for preferring one frame's judgments over another's (though in a case where one event A happens in the past ] of another event B, all frames will agree that A happened in the past of B). So, in special relativity there can be no ''physical'' basis for picking out a unique set of events that are all happening simultaneously in "the present".


In classical philosophy, time is divided into three distinct regions: the "]", the "]", and the "]". Using that representational model, the past is generally seen as being immutably fixed, and the future as at least partly undefined. As time passes, the moment that was once the present becomes part of the past, and part of the future, in turn, becomes the new present. In this way time is said to pass, with a distinct present moment moving forward into the future and leaving the past behind. One view of this type, ], argues that only the present exists. The present does not travel forward through an environment of time, moving from a real point in the past and toward a real point in the future. Instead, it merely changes. The past and future do not exist and are only concepts used to describe the real, isolated, and changing present. This conventional model presents a number of difficult philosophical problems and may be difficult to reconcile with currently accepted scientific theories such as the ].<ref name="SEP-time">{{citation|last1=Markosian |first1=Ned |author-link=Ned Markosian |title=Time |year=2014 |encyclopedia=The Stanford Encyclopedia of Philosophy |edition=Fall 2016 |editor=Edward N. Zalta |url=https://plato.stanford.edu/archives/fall2016/entries/time/ |access-date=November 18, 2017}}</ref>
===Uniqueness of a present moment===
There is no fundamental reason why a particular "present" should be more valid than any other; observers at any point in time will always consider themselves to be in the present. However, every moment of time has a "turn" at being a present moment in flow-of-time theories, so the situation ends up symmetrical even though there is still an ontological distinction between past, future, and present that is not itself symmetrical.


] is an example of the ]. Both ends of the bar pass through the ring simultaneously in the rest frame of the ring (left), but the ends of the bar pass one after the other in the rest frame of the bar (right).]]
===Rate of flow===
It can be argued that ] eliminates the concept of absolute simultaneity and a universal present: according to the ], observers in different ] can have different measurements of whether a given pair of events happened at the same time or at different times, with there being no physical basis for preferring one frame's judgments over those of another. However, there are events that may be non-simultaneous in all frames of reference: when one event is within the ] of another—its causal past or causal future—then observers in all frames of reference show that one event preceded the other. The causal past and causal future are consistent within all frames of reference, but any other time is "elsewhere", and within it there is no present, past, or future. There is no physical basis for a set of events that represents the present.<ref name="Savitt">{{citation|last1=Savitt|first1=Steven F.|title=There's No Time Like the Present (in Minkowski Spacetime)|doi=10.1086/392846|journal=Philosophy of Science|volume=67|issue=S1|date=September 2000|pages=S563–S574|citeseerx=10.1.1.14.6140|s2cid=121275903}}</ref>
The concept of "time passing" can be considered to be internally inconsistent, by asking "how much time goes by in an hour?" However, the question could be no different from "how much space is contained in a meter?" &mdash; all measurements being equally arbitrary.


Many philosophers have argued that relativity implies eternalism.<ref>{{citation|author=Thomas M. Crisp|url=http://people.biola.edu/thomasc/thomasmcrisp/Vita_files/Presentism,%20Eternalism%20and%20Relativity%20Physics.pdf|title=Presentism, Eternalism, and Relativity Physics|work=Einstein, Relativity and Absolute Simultaneity|year=2007|editor1=William Lane Craig|editor2=Quentin Smith|at=footnote 1|access-date=2012-08-07|archive-url=https://web.archive.org/web/20110428024231/http://people.biola.edu/thomasc/thomasmcrisp/Vita_files/Presentism,%20Eternalism%20and%20Relativity%20Physics.pdf|archive-date=2011-04-28|url-status=dead}}</ref> Philosopher of science Dean Rickles says that, "the consensus among philosophers seems to be that special and general relativity are incompatible with presentism."<ref>{{citation|author=Dean Rickles|year=2008|title=Symmetry, Structure, and Spacetime|page=158|isbn=9780444531162|publisher=]}}</ref> Christian Wüthrich argues that supporters of presentism can salvage absolute simultaneity only if they reject either ] or relativity.<ref name="Wuthrich2010">{{cite book |first=Christian |last=Wüthrich |year=2010 |chapter=No Presentism in Quantum Gravity |title=Space, Time, and Spacetime: Physical and Philosophical Implications of Minkowski's Unification of Space and Time |editor= Vesselin Petkov|series=Fundamental Theories of Physics |publisher=Springer |isbn=9783642135378 |lccn=2010935080 |url= http://philsci-archive.pitt.edu/5363/|pages=}}</ref> ] and others argue for ] whose judgments about length, time, and simultaneity are the ''true'' ones, even if there is no empirical way to distinguish this frame.<ref name="Zimmerman2011">{{cite book |first=Dean |last=Zimmerman |editor= C. Callender |year=2011 |title=The Oxford Handbook of Philosophy of Time |chapter=Presentism and the Space-Time Manifold |series=Oxford Handbooks in Philosophy |publisher=OUP Oxford |isbn=9780199298204 |lccn=2011283684 |url=http://fas-philosophy.rutgers.edu/zimmerman/Presentism%20and%20Rel.for.Web.2.pdf |at=pp.163-244 (PDF p.119)}}</ref><ref>{{citation|author=Yuri Balashov|title=Persistence and Spacetime|year=2010|publisher=Oxford University Press|page=222}}</ref>
=== McTaggart's argument ===


== The flow of time ==
In '']'', ] divided time into an ], with the A-series describing events in absolute tensed terms (past, present, and future) and the B-series describing events in terms of untensed temporal relations (before and after). He went on to argue that the A-series was logically incoherent and should be discarded, and that the B-series was insufficient for a proper understanding of time. He endorsed the C-series instead, which is a fixed, changeless (and therefore timeless), non-directional ordering of events. While McTaggart concluded that time is unreal, various philosophers and physicists{{Who|date=January 2010}} have held that the remaining B-series is all that is needed for a complete theory of time, sometimes referred to as the ].
=== Antiquity ===
Arguments for and against an independent flow of time have been raised since antiquity, represented by ], ], and ]: Classical fatalism argues that every ] about the future exists, and it is either true or false, hence there is a set of every true proposition about the future, which means these propositions describe the future exactly as it is, and this future is true and unavoidable. Fatalism is challenged by positing that there are propositions that are neither true nor false, for example they may be indeterminate. Reductionism questions whether time can exist independently of the relation between events, and Platonism argues that time is absolute, and it exists independently of the events that occupy it.<ref name="SEP-time" />


Earlier, pre-Socratic Greek philosopher ] of Elea had posited that existence is timeless and change is impossible (an idea popularized by his disciple ] and ]).
==The Eternalist alternative==


=== Middle ages ===
Eternalism addresses these various difficulties by considering all points in time to be equally valid frames of reference—or equally "real", if one prefers. It does not do away with the concept of past and future, but instead considers them directions rather than states of being; whether some point in time is in the future or past is entirely dependent on which frame of reference you are using as a basis for observing it.
The philosopher Katherin A. Rogers argued that ] took an eternalist view of time,<ref>Katherin A. Rogers (2007). . Faith and Philosophy 24 (1):3-27.</ref> although the philosopher ] argued against this interpretation,<ref>Brian Leftow (2009). 26 (3):297-319.</ref> suggesting that Anselm instead advocated a type of presentism. Rogers responded to this paper, defending her original interpretation.<ref>Katherin Rogers (2009). . Faith and Philosophy 26 (3):320-338.</ref> Rogers also discusses this issue in her book ''Anselm on Freedom'', using the term "four-dimensionalism" rather than "eternalism" for the view that "the present moment is not ontologically privileged", and commenting that "] and Augustine do sometimes sound rather four-dimensionalist, but Anselm is apparently the first consistently and explicitly to embrace the position."<ref>{{cite book |first=Katherin |last=Rogers |year=2008 |title=Anselm on Freedom |publisher=Oxford University Press |isbn=9780199231676 |url=https://books.google.com/books?id=lg-swy7JcEAC&pg=PA159 |page=159}}</ref> Taneli Kukkonen argues in the ''Oxford Handbook of Medieval Philosophy'' that "what Augustine's and Anselm's mix of eternalist and presentist, tenseless and tensed language tells is that medieval philosophers saw no need to choose sides" the way modern philosophers do.<ref>From Kukkonen's chapter on "Eternity" in ''The Oxford Handbook of Medieval Philosophy'' edited by John Marenbon (2012), .</ref>


] wrote that ] is ]—that time exists only within the created universe. ] took the same view, and many theologians agree. On this view, God would perceive something like a block universe, while time might appear differently to the finite beings contained within it.<ref>John Polkinghorne (2011). ''Science and Religion in Quest of Truth'', .</ref>
Since an observer at any given point in time can only remember events that are in the past relative to him, and not events that are in the future relative to him, the subjective illusion of the passage of time is maintained. The asymmetry of remembering past events but not future ones, as well as other irreversible events that progress in only one temporal direction (such as the increase in ]) gives rise to the ]. In the view suggested by Eternalism, there is no passage of time; the ticking of a clock measures durations between events much as the marks on a measuring tape measures distances between places.


=== Modern period ===
Eternalism has implications for the concept of ], in that it proposes that future events are as immutably fixed and impossible to change as past events (see ]). However as the human subject, and any free will they have, is also 'present' throughout time, during their life, they may be exercising free will in the 'future' as it were.
One of the most famous arguments about the nature of time in modern philosophy is presented in '']'' by ].<ref name=McT>J. M. E. McTaggart, "The Unreality of Time", '']'' 17: 457–73; reprinted in J. M. E. McTaggart, ''The Nature of Existence'', Vol. 2, 1927, Cambridge: Cambridge University Press: Book 5, Chapter 33.</ref> It argues that time is an illusion. McTaggart argued that the description of events as existing in absolute time is self-contradictory, because the events have to have properties about being in the past and in the future, which are incompatible with each other. McTaggart viewed this as a contradiction in the concept of time itself, and concluded that reality is non-temporal. He called this concept the ].<ref name="SEP-time" />


Dirck Vorenkamp, a professor of religious studies, argued in his paper "B-Series Temporal Order in Dogen's Theory of Time"<ref>Vorenkamp, Dirck (1995). . ''Philosophy East and West'', Volume 45, Number 3, 1995 July, P.387-408.</ref> that the ] Buddhist teacher ] presented views on time that contained all the main elements of McTaggart's B-series view of time (which denies any objective present), although he noted that some of Dōgen's reasoning also contained A-Series notions, which Vorenkamp argued may indicate some inconsistency in Dōgen's thinking.
Eternalism makes two assumptions, which are separable. One is that time is a full-fledged real ]. The other is immutability. The latter is not a necessary consequence of the first. A universe in which random changes are possible may be indistinguishable from the ] of quantum mechanics in which there are multiple "block times."


Eternalism also encapsulates the theory of world lines, and the concept of linear reality that is - the individual perception of linear time.<ref>{{cite book |last1=Schneider |first1=Susan |title=Science Fiction and Philosophy:From Time Travel To SuperIntelligence |date=2016 |publisher=John Wiley&Sons |isbn=9781405149075 |pages=370–384 |edition=2nd}}</ref>
] wrote that ] is ]&mdash;that time exists only within the created universe. Many theologians agree. On this view, God would perceive something like a block universe, while time might appear differently to the finite beings contained within it.


== Philosophical objections == === Quantum physics ===
Some philosophers appeal to a specific theory that is "timeless" in a more radical sense than the rest of physics, the theory of ]. This theory is used, for instance, in ]'s theory of timelessness.<ref></ref> On the other hand, George Ellis argues that time is absent in cosmological theories because of the details they leave out.<ref>{{cite journal |author1=Ellis |doi=10.1007/s10714-006-0332-z |journal=Gen. Rel. Grav. |volume=38 |title=Physics in the Real Universe: Time and Spacetime |issue=12 |pages=1797–1824 |year=2006 |arxiv=gr-qc/0605049|bibcode=2006GReGr..38.1797E |s2cid=119540219 }}</ref>


Recently, Hrvoje Nikolić has argued that a block time model solves the ].<ref>{{cite journal |author1=Nikolic H. |doi=10.1016/j.physletb.2009.06.029 |journal=Phys. Lett. B |volume=678 |title=Resolving the black-hole information paradox by treating time on an equal footing with space |issue= 2|pages= 218–221|year=2009 |arxiv=0905.0538|bibcode=2009PhLB..678..218N |s2cid=15074164 }}</ref>
Philosophers such as ] argue that "The Block universe gives a deeply inadequate view of time. It fails to account for the passage of time, the pre-eminence of the present, the directedness of time and the difference between the future and the past"<ref>]''The Future'' p8</ref>


== Objections ==
The comment summarizes the main objections. In more detail, they are:


Philosophers such as ] argue that "The Block universe gives a deeply inadequate view of time. It fails to account for the passage of time, the pre-eminence of the present, the directedness of time and the difference between the future and the past."<ref>]''The Future'' p8</ref> Similarly, ] argued in his discussion with ] against determinism and eternalism from a common-sense standpoint.<ref name="Popper2002">{{cite book |first=K.R. |last=Popper |year=2002 |title=Unended Quest: An Intellectual Autobiography |series=Routledge Classics |publisher=Routledge |isbn=9780415285896 |lccn=2002067996 |url=https://books.google.com/books?id=CxND59gFftMC&pg=PA148 |pages=148–150}}</ref>
=== Subjective sense of flow ===


A flow-of-time theory with a strictly ] future, which nonetheless does not exist in the same sense as the present, would not satisfy common-sense intuitions about time. Some have argued that common-sense flow-of-time theories can be compatible with eternalism, for example ]’s ]. Kastner (2010) "proposed that in order to preserve the elegance and economy of the interpretation, it may be necessary to consider offer and confirmation waves as propagating in a “higher space” of possibilities.<ref name="Kastner2010">{{cite journal |title=The Quantum Liar Experiment Kastner|journal=Studies in History and Philosophy of Modern Physics |volume=41| issue = 2}}</ref>
Whilst the idea that there is some objective sense in which time is flowing can be denied, the fact that conscious beings feel as though it is in some sense flowing cannot. However, if the flow of time didn't have an objective existence, then it is argued conscious beings would simultaneously experience all moments in their lives. A response is that since the brain presumably perceives time through information processing of external stimuli, not by extrasensory perception, and obeys the laws of causality, it is hard to see how the flow of time, whether it exists or not, could make any subjective difference: all conscious beings are built to perceive time as a chain of events, whether or not it occurs as such.


In '']'', ] argues that time is physically fundamental, in contrast to Einstein's view that time is an illusion. Smolin hypothesizes that the laws of physics are not fixed, but rather evolve over time via a form of cosmological natural selection.<ref>"Time Reborn: a new theory of time - a new view of the world". Royal Society of Arts. May 21, 2013. Archived from the original on July 28, 2013.</ref><ref>{{cite journal |last1=Cortês |first1=Marina |last2=Smolin |first2=Lee |title=The universe as a process of unique events |journal=Physical Review D |date=6 October 2014 |volume=90 |issue=8 |pages=084007 |arxiv=1307.6167 |doi=10.1103/PhysRevD.90.084007|bibcode=2014PhRvD..90h4007C |s2cid=118557476 }}</ref> In '']'', co-authored with philosopher ], Smolin goes into more detail on his views on the physical passage of time. In contrast to the orthodox block universe view, Smolin argues that what instead exists is a "thick present"<ref>{{cite journal |last1=Smolin |first1=Lee |title=Temporal naturalism |journal=Studies in History and Philosophy of Science Part B |date=2015 |volume=52 |pages=86–102 |arxiv=1310.8539 |doi=10.1016/j.shpsb.2015.03.005|bibcode=2015SHPMP..52...86S |s2cid=8344858 }}</ref><ref>{{cite book |last=Smolin |first=Lee |chapter=Temporal Relationalism |editor1=Nick Huggett |editor2=Keizo Matsubara |editor3=Christian Wuthrich|title=Beyond Spacetime |date=30 April 2020 |pages=143–175 |arxiv=1805.12468 |doi=10.1017/9781108655705.010|isbn=9781108655705 |s2cid=118936279 }}</ref> in which two events in the present can be causally related to each other. Marina Cortês and Lee Smolin also argue that certain classes of discrete dynamical systems demonstrate time asymmetry and irreversibility, which is inconsistent with the block universe interpretation of time.<ref>{{cite journal |last1=Cortês |first1=Marina |last2=Smolin |first2=Lee |title=Reversing the irreversible: From limit cycles to emergent time symmetry |journal=Physical Review D |date=10 January 2018 |volume=97 |issue=2 |pages=026004 |arxiv=1703.09696 |doi=10.1103/PhysRevD.97.026004|bibcode=2018PhRvD..97b6004C |s2cid=119067096 }}</ref>
=== Apparent differences between past, present and future ===
Many of our common-sense attitudes treat the past, present and future differently.


] vehemently rejects the block universe interpretation of time. At the Time in Cosmology conference, held at the ] in 2016, Elitzur said: "I’m sick and tired of this block universe, ... I don’t think that next Thursday has the same footing as this Thursday. The future does not exist. It does not! Ontologically, it’s not there."<ref>Falk, D. (2016, July 19). A Debate Over the Physics of Time. Retrieved February 14, 2019, from https://www.quantamagazine.org/a-debate-over-the-physics-of-time-20160719/</ref> Elitzur and Shahar Dolev argue that quantum mechanical experiments such as the Quantum Liar<ref>{{cite book |last1=Elitzur |first1=Avshalom C. |last2=Dolev |first2=Shahar |chapter=Quantum Phenomena Within a New Theory of Time |chapter-url=https://www.researchgate.net/publication/226976724 |title=Quo Vadis Quantum Mechanics? |series=The Frontiers Collection |date=2005 |pages=325–349 |doi=10.1007/3-540-26669-0_17|isbn=3-540-22188-3 }}</ref> and the evaporation of black holes<ref>{{cite journal |last1=Elitzur |first1=Avshalom C. |last2=Dolev |first2=Shahar |title=Black Hole Evaporation Entails an Objective Passage of Time |journal=Foundations of Physics Letters |date=1999 |volume=12 |issue=4 |pages=309–323 |arxiv=quant-ph/0012081 |doi=10.1023/A:1021644319368|bibcode=1999FoPhL..12..309E |s2cid=15532826 }}</ref> challenge the mainstream block universe model, and support the existence of an objective passage of time. Elitzur and Dolev believe that an objective passage of time and relativity can be reconciled, and that it would resolve many of the issues with the block universe and the conflict between relativity and quantum mechanics.<ref>{{cite book |last1=Elitzur |first1=Avshalom C. |last2=Dolev |first2=Shahar |chapter=Becoming as a bridge between quantum mechanics and relativity |chapter-url=https://www.researchgate.net/publication/228343669 |title=Endophysics, Time, Quantum and the Subjective |date=2005 |pages=589–606 |doi=10.1142/9789812701596_0031|isbn=978-981-256-509-9 }}</ref> Additionally, Elitzur and Dolev believe that certain quantum mechanical experiments provide evidence of apparently inconsistent histories, and that spacetime itself may therefore be subject to change affecting entire histories.<ref>{{cite book |last1=Elitzur |first1=A. C. |last2=Dolev |first2=S. |year=2003 |arxiv=quant-ph/0207029 |chapter=Is there more to T |title=The Nature of Time: Geometry, Physics and Perception |pages=297–306 |publisher=Springer |location=Dordrecht}}</ref>
# We apparently fear death because we believe that we will no longer exist after we die. But if Eternalism is correct, death is just one of our temporal borders, and should be no more worrisome than birth.
# You are about to go to the dentist, or you have already been. Commonsense says you should prefer to have been. But if Eternalism is correct, it shouldn't matter which situation you're in.
# When some unpleasant experience is behind us, we feel glad that it is over. But if the Eternalism is correct, there is no such property as being over or no longer happening now—it continues to exist timelessly.

=== Status of conscious observers ===

Eternalists often appeal to the idea that the flow of time is a subjective illusion. However, Eternalism takes its inspiration from physics {{Citation needed|date=February 2011}} and needs to give a physical account of observers. One could, for instance, portray conscious observers as moving through the block universe, in some physically inexplicable way, in order to account for the subjective sense of a flow of time. But there is no need to do so to explain the subjective flow of time.{{Citation needed|date=February 2011}} Their opponents claim that the time-flow itself, as an objective phenomenon, is physically inexplicable, and that physics is simply misrepresenting time in treating it as a dimension.{{Citation needed|date=February 2011}}

===Determinism and indeterminism===

Previously, it was noted that people tend to have very different attitudes towards the past and the future. This might be explained by an underlying attitude that the future is not fixed, but can be changed, and is therefore worth worrying about.* If that is correct, the flow of time is perhaps less important to our intuitions than an open, undetermined, future. In other words, a flow-of-time theory with a strictly ] future (which nonetheless does not exist at the present) would not satisfy common-sense intuitions about time. If indeterminism can be removed from flow-of-time theories, can it be added to Eternalist theories? Surprisingly, the answer is a qualified "yes" in the form of ] theories, where multiple alternate futures exist in a fixed framework, but individual observers have no way of knowing which alternative, or "branch" they will end up in.

{{Or|date=April 2012}}

== Relation to physics ==

Eternalism takes its inspiration from physics, especially the ], in which the relativity of simultaneity is used to show that each point in the universe can have a different set of events that are in its present moment. According to ] this is impossible because there is only one present moment that is instantaneous and encompasses the entire universe.

Some philosophers also appeal to a specific theory which is "timeless" in a more radical sense than the rest of physics, the theory of ]. This theory is used, for instance, in ]'s theory of timelessness.<ref></ref> On the other hand, George Ellis argues that time is absent in cosmological theories because of the details they leave out.<ref>{{cite journal |author1=Ellis |doi=10.1007/s10714-006-0332-z |journal=Gen.Rel.Grav. |volume=38 |title=Physics in the Real Universe: Time and Spacetime |issue=12 |pages=1797–1824 |year=2006 |arxiv=gr-qc/0605049}}</ref>

== Relation to Eastern body of thought ==

In ], a special term ] is translated as 'total field of events and meanings' or 'field of all events and meanings.' Here the 'Block Universe' seems to be encompassing not only every possible event in the physical universe but also having a psychological component.
See: ]

==In fiction==
Eternalism is a major theme in ]’s novel, ]. The Tralfamadorians, an alien species in the novel, have a four-dimensional sight and can therefore see all points in time simultaneously. They explain that since all moments exist simultaneously, everyone is always alive. The hero, Billy Pilgrim, lives his life out of sequence, which, among other things, means that his point of death occurs at a random point in his life rather than at the end of it.

Eternalism also appears in the comic book series '']'' by ]. In one chapter, ] explains how he perceives time. Since past, present, and future events all occur at the "same time" for him, he speaks about them all in the present tense. For example, he says "Forty years ago, cogs rain on Brooklyn" referring to an event in his youth when his father throws old watch parts out a window. His last line of the series is "Nothing ends, ]. Nothing ever ends."


==See also== ==See also==
* ] * ]
* ]
* ]
* ] * ]
* ]
* ]
* ]
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* ]
* ]


==References==
==Footnotes and references==
{{reflist}} {{Reflist}}

==Bibliography==
* Smart, Jack. "River of Time". In Anthony Kenny. Essays in Conceptual Analysis. pp.&nbsp;214–215.
* van Inwagen, Peter (2008). "Metaphysics." Stanford Encyclopedia of Philosophy.


==External links== ==External links==
* {{cite journal|author1=Biswas|author2=Shaw|author3=Modak|doi=10.1142/S0218271801001384|journal=Int.J.Mod.Phys. D |volume=10|title=Time in Quantum Gravity|issue=4|pages=595|year=1999|arxiv=gr-qc/9906010}} * {{cite journal|author1=Biswas|author2=Shaw|author3=Modak|doi=10.1142/S0218271801001384|journal= International Journal of Modern Physics D|volume=10|title=Time in Quantum Gravity|issue=4|pages=595–606|year=1999|arxiv=gr-qc/9906010|bibcode=2001IJMPD..10..595B|s2cid=119472003}}
*{{cite journal| title=That Mysterious Flow| journal=Scientific American| month=September| year=2002| volume=287| issue=3| pages=40–45| first=Paul| last=Davies| doi=10.1038/scientificamerican0902-40}} * {{cite journal| title=That Mysterious Flow| journal=Scientific American|date=September 2002| volume=287| issue=3| pages=40–45| first=Paul| last=Davies| doi=10.1038/scientificamerican0902-40| pmid=12197100| bibcode=2002SciAm.287c..40D}}
* {{cite encyclopedia| url=http://plato.stanford.edu/entries/time/#3D4Con| title=Time: 8. The 3D/4D Controversy| encyclopedia=Stanford Encyclopedia of Philosophy| access-date=2006-12-20| year=2002| first=Ned| last= Markosian}}
*
* {{cite web| url=http://plato.stanford.edu/entries/time/#3D4Con| title=Time: 8. The 3D/4D Controversy| work=Stanford Encyclopedia of Philosophy| accessdate=2006-12-20| year=2002| first=Ned| last= Markosian}}
* {{cite web| url=http://fqxi.org/data/essay-contest-files/Nikolic_FQXi_time.pdf| * {{cite web| url=http://fqxi.org/data/essay-contest-files/Nikolic_FQXi_time.pdf|
first= Hrvoje| last= Nikolic| title= Block time: Why many physicists still don't accept it?}} first= Hrvoje| last= Nikolic| title= Block time: Why many physicists still don't accept it?}}
* {{cite book |last=Barbour |first=Julian |date=1999 |title=The End of Time |publisher=Oxford University Press |isbn=0195145925 }}
*{{cite web| url=http://Philsci-Archive.Pitt.EDU/archive/00002408/| title= Is There an Alternative to the Block Universe View?| last= Petkov| first= Vesselin| year=2005| format=PDF| publisher=PhilSci Archive| accessdate=2006-12-20}}
* Slavov, Matias (2024) "" ''The Internet Encyclopedia of Philosophy''. ISSN 2161-0002.
* {{cite arxiv| eprint=0910.2724/| title= Four-dimensional understanding of quantum mechanics| last= Duda| first= J| year=2009}}
{{Time travel}}
{{Time Topics}} {{Time Topics}}
{{Time in philosophy}} {{Time in philosophy}}


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Latest revision as of 01:14, 23 September 2024

Philosophical view that there is no correct way of perceiving the passage of time
Illustration of the concept of eternalism, showing a man walking his dog. Time progresses through the series of snapshots from the bottom of the page to the top. In a common sense view of time, each of those four instants would exist one after another. According to eternalism, those four instants all equally exist.

In the philosophy of space and time, eternalism is an approach to the ontological nature of time, which takes the view that all existence in time is equally real, as opposed to presentism or the growing block universe theory of time, in which at least the future is not the same as any other time. Some forms of eternalism give time a similar ontology to that of space, as a dimension, with different times being as real as different places, and future events are "already there" in the same sense other places are already there, and that there is no objective flow of time.

It is sometimes referred to as the "block time" or "block universe" theory due to its description of space-time as an unchanging four-dimensional "block", as opposed to the view of the world as a three-dimensional space modulated by the passage of time.

The present

In classical philosophy, time is divided into three distinct regions: the "past", the "present", and the "future". Using that representational model, the past is generally seen as being immutably fixed, and the future as at least partly undefined. As time passes, the moment that was once the present becomes part of the past, and part of the future, in turn, becomes the new present. In this way time is said to pass, with a distinct present moment moving forward into the future and leaving the past behind. One view of this type, presentism, argues that only the present exists. The present does not travel forward through an environment of time, moving from a real point in the past and toward a real point in the future. Instead, it merely changes. The past and future do not exist and are only concepts used to describe the real, isolated, and changing present. This conventional model presents a number of difficult philosophical problems and may be difficult to reconcile with currently accepted scientific theories such as the theory of relativity.

The bar and ring paradox is an example of the relativity of simultaneity. Both ends of the bar pass through the ring simultaneously in the rest frame of the ring (left), but the ends of the bar pass one after the other in the rest frame of the bar (right).

It can be argued that special relativity eliminates the concept of absolute simultaneity and a universal present: according to the relativity of simultaneity, observers in different frames of reference can have different measurements of whether a given pair of events happened at the same time or at different times, with there being no physical basis for preferring one frame's judgments over those of another. However, there are events that may be non-simultaneous in all frames of reference: when one event is within the light cone of another—its causal past or causal future—then observers in all frames of reference show that one event preceded the other. The causal past and causal future are consistent within all frames of reference, but any other time is "elsewhere", and within it there is no present, past, or future. There is no physical basis for a set of events that represents the present.

Many philosophers have argued that relativity implies eternalism. Philosopher of science Dean Rickles says that, "the consensus among philosophers seems to be that special and general relativity are incompatible with presentism." Christian Wüthrich argues that supporters of presentism can salvage absolute simultaneity only if they reject either empiricism or relativity. Dean Zimmerman and others argue for a single privileged frame whose judgments about length, time, and simultaneity are the true ones, even if there is no empirical way to distinguish this frame.

The flow of time

Antiquity

Arguments for and against an independent flow of time have been raised since antiquity, represented by fatalism, reductionism, and Platonism: Classical fatalism argues that every proposition about the future exists, and it is either true or false, hence there is a set of every true proposition about the future, which means these propositions describe the future exactly as it is, and this future is true and unavoidable. Fatalism is challenged by positing that there are propositions that are neither true nor false, for example they may be indeterminate. Reductionism questions whether time can exist independently of the relation between events, and Platonism argues that time is absolute, and it exists independently of the events that occupy it.

Earlier, pre-Socratic Greek philosopher Parmenides of Elea had posited that existence is timeless and change is impossible (an idea popularized by his disciple Zeno of Elea and his paradoxes about motion).

Middle ages

The philosopher Katherin A. Rogers argued that Anselm of Canterbury took an eternalist view of time, although the philosopher Brian Leftow argued against this interpretation, suggesting that Anselm instead advocated a type of presentism. Rogers responded to this paper, defending her original interpretation. Rogers also discusses this issue in her book Anselm on Freedom, using the term "four-dimensionalism" rather than "eternalism" for the view that "the present moment is not ontologically privileged", and commenting that "Boethius and Augustine do sometimes sound rather four-dimensionalist, but Anselm is apparently the first consistently and explicitly to embrace the position." Taneli Kukkonen argues in the Oxford Handbook of Medieval Philosophy that "what Augustine's and Anselm's mix of eternalist and presentist, tenseless and tensed language tells is that medieval philosophers saw no need to choose sides" the way modern philosophers do.

Augustine of Hippo wrote that God is outside of time—that time exists only within the created universe. Thomas Aquinas took the same view, and many theologians agree. On this view, God would perceive something like a block universe, while time might appear differently to the finite beings contained within it.

Modern period

One of the most famous arguments about the nature of time in modern philosophy is presented in The Unreality of Time by J. M. E. McTaggart. It argues that time is an illusion. McTaggart argued that the description of events as existing in absolute time is self-contradictory, because the events have to have properties about being in the past and in the future, which are incompatible with each other. McTaggart viewed this as a contradiction in the concept of time itself, and concluded that reality is non-temporal. He called this concept the B-theory of time.

Dirck Vorenkamp, a professor of religious studies, argued in his paper "B-Series Temporal Order in Dogen's Theory of Time" that the Zen Buddhist teacher Dōgen presented views on time that contained all the main elements of McTaggart's B-series view of time (which denies any objective present), although he noted that some of Dōgen's reasoning also contained A-Series notions, which Vorenkamp argued may indicate some inconsistency in Dōgen's thinking.

Eternalism also encapsulates the theory of world lines, and the concept of linear reality that is - the individual perception of linear time.

Quantum physics

Some philosophers appeal to a specific theory that is "timeless" in a more radical sense than the rest of physics, the theory of quantum gravity. This theory is used, for instance, in Julian Barbour's theory of timelessness. On the other hand, George Ellis argues that time is absent in cosmological theories because of the details they leave out.

Recently, Hrvoje Nikolić has argued that a block time model solves the black hole information paradox.

Objections

Philosophers such as John Lucas argue that "The Block universe gives a deeply inadequate view of time. It fails to account for the passage of time, the pre-eminence of the present, the directedness of time and the difference between the future and the past." Similarly, Karl Popper argued in his discussion with Albert Einstein against determinism and eternalism from a common-sense standpoint.

A flow-of-time theory with a strictly deterministic future, which nonetheless does not exist in the same sense as the present, would not satisfy common-sense intuitions about time. Some have argued that common-sense flow-of-time theories can be compatible with eternalism, for example John G. Cramer’s transactional interpretation. Kastner (2010) "proposed that in order to preserve the elegance and economy of the interpretation, it may be necessary to consider offer and confirmation waves as propagating in a “higher space” of possibilities.

In Time Reborn, Lee Smolin argues that time is physically fundamental, in contrast to Einstein's view that time is an illusion. Smolin hypothesizes that the laws of physics are not fixed, but rather evolve over time via a form of cosmological natural selection. In The Singular Universe and the Reality of Time, co-authored with philosopher Roberto Mangabeira Unger, Smolin goes into more detail on his views on the physical passage of time. In contrast to the orthodox block universe view, Smolin argues that what instead exists is a "thick present" in which two events in the present can be causally related to each other. Marina Cortês and Lee Smolin also argue that certain classes of discrete dynamical systems demonstrate time asymmetry and irreversibility, which is inconsistent with the block universe interpretation of time.

Avshalom Elitzur vehemently rejects the block universe interpretation of time. At the Time in Cosmology conference, held at the Perimeter Institute for Theoretical Physics in 2016, Elitzur said: "I’m sick and tired of this block universe, ... I don’t think that next Thursday has the same footing as this Thursday. The future does not exist. It does not! Ontologically, it’s not there." Elitzur and Shahar Dolev argue that quantum mechanical experiments such as the Quantum Liar and the evaporation of black holes challenge the mainstream block universe model, and support the existence of an objective passage of time. Elitzur and Dolev believe that an objective passage of time and relativity can be reconciled, and that it would resolve many of the issues with the block universe and the conflict between relativity and quantum mechanics. Additionally, Elitzur and Dolev believe that certain quantum mechanical experiments provide evidence of apparently inconsistent histories, and that spacetime itself may therefore be subject to change affecting entire histories.

See also

References

  1. Le Bihan, Baptiste (2020). "String theory, loop quantum gravity and eternalism". European Journal for Philosophy of Science. 10 (2): 17. arXiv:2005.09335. doi:10.1007/s13194-020-0275-3. S2CID 210958803.
  2. Kuipers, Theo A.F. (2007). General Philosophy of Science: Focal Issues. North Holland. p. 326. ISBN 978-0-444-51548-3.
  3. Tim Maudlin (2010), "On the Passing of Time", The Metaphysics Within Physics, Oxford University Press, ISBN 9780199575374
  4. ^ Markosian, Ned (2014), "Time", in Edward N. Zalta (ed.), The Stanford Encyclopedia of Philosophy (Fall 2016 ed.), retrieved November 18, 2017
  5. Savitt, Steven F. (September 2000), "There's No Time Like the Present (in Minkowski Spacetime)", Philosophy of Science, 67 (S1): S563 – S574, CiteSeerX 10.1.1.14.6140, doi:10.1086/392846, S2CID 121275903
  6. Thomas M. Crisp (2007), William Lane Craig; Quentin Smith (eds.), "Presentism, Eternalism, and Relativity Physics" (PDF), Einstein, Relativity and Absolute Simultaneity, footnote 1, archived from the original (PDF) on 2011-04-28, retrieved 2012-08-07
  7. Dean Rickles (2008), Symmetry, Structure, and Spacetime, Elsevier, p. 158, ISBN 9780444531162
  8. Wüthrich, Christian (2010). "No Presentism in Quantum Gravity". In Vesselin Petkov (ed.). Space, Time, and Spacetime: Physical and Philosophical Implications of Minkowski's Unification of Space and Time. Fundamental Theories of Physics. Springer. pp. 262–264. ISBN 9783642135378. LCCN 2010935080.
  9. Zimmerman, Dean (2011). "Presentism and the Space-Time Manifold". In C. Callender (ed.). The Oxford Handbook of Philosophy of Time (PDF). Oxford Handbooks in Philosophy. OUP Oxford. pp.163-244 (PDF p.119). ISBN 9780199298204. LCCN 2011283684.
  10. Yuri Balashov (2010), Persistence and Spacetime, Oxford University Press, p. 222
  11. Katherin A. Rogers (2007). "Anselmian Eternalism". Faith and Philosophy 24 (1):3-27.
  12. Brian Leftow (2009). "Anselmian Presentism. Faith and Philosophy" 26 (3):297-319.
  13. Katherin Rogers (2009). "Back to Eternalism". Faith and Philosophy 26 (3):320-338.
  14. Rogers, Katherin (2008). Anselm on Freedom. Oxford University Press. p. 159. ISBN 9780199231676.
  15. From Kukkonen's chapter on "Eternity" in The Oxford Handbook of Medieval Philosophy edited by John Marenbon (2012), p. 529.
  16. John Polkinghorne (2011). Science and Religion in Quest of Truth, p. 64.
  17. J. M. E. McTaggart, "The Unreality of Time", Mind 17: 457–73; reprinted in J. M. E. McTaggart, The Nature of Existence, Vol. 2, 1927, Cambridge: Cambridge University Press: Book 5, Chapter 33.
  18. Vorenkamp, Dirck (1995). "B-Series Temporal Order in Dogen's Theory of Time". Philosophy East and West, Volume 45, Number 3, 1995 July, P.387-408.
  19. Schneider, Susan (2016). Science Fiction and Philosophy:From Time Travel To SuperIntelligence (2nd ed.). John Wiley&Sons. pp. 370–384. ISBN 9781405149075.
  21. Ellis (2006). "Physics in the Real Universe: Time and Spacetime". Gen. Rel. Grav. 38 (12): 1797–1824. arXiv:gr-qc/0605049. Bibcode:2006GReGr..38.1797E. doi:10.1007/s10714-006-0332-z. S2CID 119540219.
  22. Nikolic H. (2009). "Resolving the black-hole information paradox by treating time on an equal footing with space". Phys. Lett. B. 678 (2): 218–221. arXiv:0905.0538. Bibcode:2009PhLB..678..218N. doi:10.1016/j.physletb.2009.06.029. S2CID 15074164.
  23. John LucasThe Future p8
  24. Popper, K.R. (2002). Unended Quest: An Intellectual Autobiography. Routledge Classics. Routledge. pp. 148–150. ISBN 9780415285896. LCCN 2002067996.
  25. "The Quantum Liar Experiment Kastner". Studies in History and Philosophy of Modern Physics. 41 (2).
  26. "Time Reborn: a new theory of time - a new view of the world". Royal Society of Arts. May 21, 2013. Archived from the original on July 28, 2013.
  27. Cortês, Marina; Smolin, Lee (6 October 2014). "The universe as a process of unique events". Physical Review D. 90 (8): 084007. arXiv:1307.6167. Bibcode:2014PhRvD..90h4007C. doi:10.1103/PhysRevD.90.084007. S2CID 118557476.
  28. Smolin, Lee (2015). "Temporal naturalism". Studies in History and Philosophy of Science Part B. 52: 86–102. arXiv:1310.8539. Bibcode:2015SHPMP..52...86S. doi:10.1016/j.shpsb.2015.03.005. S2CID 8344858.
  29. Smolin, Lee (30 April 2020). "Temporal Relationalism". In Nick Huggett; Keizo Matsubara; Christian Wuthrich (eds.). Beyond Spacetime. pp. 143–175. arXiv:1805.12468. doi:10.1017/9781108655705.010. ISBN 9781108655705. S2CID 118936279.
  30. Cortês, Marina; Smolin, Lee (10 January 2018). "Reversing the irreversible: From limit cycles to emergent time symmetry". Physical Review D. 97 (2): 026004. arXiv:1703.09696. Bibcode:2018PhRvD..97b6004C. doi:10.1103/PhysRevD.97.026004. S2CID 119067096.
  31. Falk, D. (2016, July 19). A Debate Over the Physics of Time. Retrieved February 14, 2019, from https://www.quantamagazine.org/a-debate-over-the-physics-of-time-20160719/
  32. Elitzur, Avshalom C.; Dolev, Shahar (2005). "Quantum Phenomena Within a New Theory of Time". Quo Vadis Quantum Mechanics?. The Frontiers Collection. pp. 325–349. doi:10.1007/3-540-26669-0_17. ISBN 3-540-22188-3.
  33. Elitzur, Avshalom C.; Dolev, Shahar (1999). "Black Hole Evaporation Entails an Objective Passage of Time". Foundations of Physics Letters. 12 (4): 309–323. arXiv:quant-ph/0012081. Bibcode:1999FoPhL..12..309E. doi:10.1023/A:1021644319368. S2CID 15532826.
  34. Elitzur, Avshalom C.; Dolev, Shahar (2005). "Becoming as a bridge between quantum mechanics and relativity". Endophysics, Time, Quantum and the Subjective. pp. 589–606. doi:10.1142/9789812701596_0031. ISBN 978-981-256-509-9.
  35. Elitzur, A. C.; Dolev, S. (2003). "Is there more to T". The Nature of Time: Geometry, Physics and Perception. Dordrecht: Springer. pp. 297–306. arXiv:quant-ph/0207029.

Bibliography

  • Smart, Jack. "River of Time". In Anthony Kenny. Essays in Conceptual Analysis. pp. 214–215.
  • van Inwagen, Peter (2008). "Metaphysics." Stanford Encyclopedia of Philosophy.

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