Fontem paginae Tempus inspicere

{{FA stella}}
[[Fasciculus:Montinari_Milano.jpg|thumb|[[Horologium armillare]].]]
[[Fasciculus:Wooden hourglass 3.jpg|thumb|Fluxus [[harena]]e in [[Clepsydra (horologium)|clepsydra]] adhiberi potest ad metiendum tempus intercessum.]]
'''Tempus''' {{victio|tempus|oris|n}} nuncupatur et eventuum durationum [[mensura]]<ref>{{cite web |url=http://www.macmillandictionary.com/dictionary/american/time |title=MacMillan Dictionary |year=2010 |quote=''the quantity that you measure using a clock'' ([[Latine]] "quantitas quam horologio metiris"}}</ref> et [[continuum (theoria)|continuum]] abstractum in quo ipsi eventus accidunt, quod tribus partibus temporum [[praeteritum|praeteriti]], [[tempus praesens|praesentis]], et [[tempus futurum|futuri]] successione rationali ordinatis constat.<ref>Seneca, ''ep.'' 124.7. Nota [[Seneca]]m futurum appellavisse venturum.</ref><ref>{{cite web |url=http://www.yourdictionary.com/time |title=The American Heritage® Dictionary of the English Language |edition=4th |year=2010 |quote=
1a. A nonspatial continuum in which events occur in apparently irreversible succession from the past through the present to the future. 1b. An interval separating two points on this continuum; a duration: a long time since the last war; passed the time reading. 1c. A number, as of years, days, or minutes, representing such an interval: ran the course in a time just under four minutes. 1d. A similar number representing a specific point on this continuum, reckoned in hours and minutes: checked her watch and recorded the time, 6:17 A.M. 1e. A system by which such intervals are measured or such numbers are reckoned: solar time. . . . 11. The rate of speed of a measured activity: marching in double time.}}</ref> 

Physici quidem strictiore sensu tempus definiunt sicut [[quantitas|quantitatem]] unius [[dimensio (mensura)|dimensionis]]<ref name=quantity>{{cite web |url=http://www.iep.utm.edu/time/ |title=Internet Encyclopedia of Philosophy |year=2010 |quote=Time is what clocks measure. We use time to place events in sequence one after the other, and we use time to compare how long events last. . . . Among philosophers of physics, the most popular short answer to the question "What is physical time?" is that it is not a substance or object but rather a special system of relations among instantaneous events. This working definition is offered by Adolf Grünbaum who applies the contemporary mathematical theory of continuity to physical processes, and he says time is a linear continuum of instants and is a distinguished one-dimensional sub-space of four-dimensional spacetime.}}
* {{cite web |url=http://www.thefreedictionary.com/time |title=Collins English Dictionary |publisher=HarperCollins |year=2003 |quote=2. (Physics) a quantity measuring duration, usually with reference to a periodic process such as the rotation of the earth or the vibration of electromagnetic radiation emitted from certain atoms. . . . In classical mechanics, time is absolute in the sense that the time of an event is independent of the observer. According to the theory of relativity it depends on the observer's frame of reference. Time is considered as a fourth coordinate required, along with three spatial coordinates, to specify an event. See space-time continuum.}}
* {{cite web |url=http://scienceworld.wolfram.com/physics/Time.html |title=Eric Weisstein's World of Science |year=2007 |quote=A quantity used to specify the order in which events occurred and measure the amount by which one even preceded or followed another. In special relativity, ct (where c is the speed of light and t is time), plays the role of a fourth dimension.}}
* {{cite web |url=http://nedwww.ipac.caltech.edu/level5/Glossary/Glossary_T.html |title=Glossary for Extragalactic Astronomy |year=2005 |quote=A dimension distinguishing past, present, and future. In relativity, time is portrayed as a geometrical dimension, analogous to the dimensions of space. |publisher=CalTech}}
</ref> adhibita ad eventus in seriem definitam ordinandos, ut [[spatium|durationes]] eventuum eorumque [[spatium|intervalla]] [[quantificatio|enumerentur]], et ut enumerentur scianturque [[motus (physica)|motus]] [[corpus physicum|rerum]] aliarumque mutationum.<ref name=DicDefs> {{cite web |url=http://www.merriam-webster.com/dictionary/time |title=Merriam Webster Online Dictionary |year=2010 |quote=1a: the measured or measurable period during which an action, process, or condition exists or continues: duration; 1b: a nonspatial continuum that is measured in terms of events which succeed one another from past through present to future; 2: the point or period when something occurs : occasion}}
* {{cite encyclopedia |url=http://encarta.msn.com/encnet/features/dictionary/DictionaryResults.aspx?refid=1861720331 |title=Encarta Online Dictionary |year=2010 |quote=1. system of distinguishing events: a dimension that enables two identical events occurring at the same point in space to be distinguished, measured by the interval between the events.}}
* {{cite web |url=http://www.yourdictionary.com/time |title=Webster's New World College Dictionary |year=2010 |quote=1.indefinite, unlimited duration in which things are considered as happening in the past, present, or future; every moment there has ever been or ever will be . . . a system of measuring duration 2.the period between two events or during which something exists, happens, or acts; measured or measurable interval}}
* {{cite web |url=http://dictionary.reference.com/browse/time?r=66 |title=Dictionary.com Unabridged, based on Random House Dictionary |year=2010 |quote=1. the system of those sequential relations that any event has to any other, as past, present, or future; indefinite and continuous duration regarded as that in which events succeed one another. . . . 3. ( sometimes initial capital letter ) a system or method of measuring or reckoning the passage of time: mean time; apparent time; Greenwich Time. 4. a limited period or interval, as between two successive events: a long time. . . . 14. a particular or definite point in time, as indicated by a clock: What time is it? . . . 18. an indefinite, frequently prolonged period or duration in the future: Time will tell if what we have done here today was right.}}
* {{cite web |url=http://dictionary.reference.com/browse/time?r=66 |title=The American Heritage® Stedman's Medical Dictionary @dictionary.com |year=2002 |quote=A duration or relation of events expressed in terms of past, present, and future, and measured in units such as minutes, hours, days, months, or years.}}
* {{cite web |url=http://www.collinslanguage.com/results.aspx?context=3&reversed=False&action=define&homonym=-1&text=time |title=Collins Language.com |publisher=HarperCollins |year=2010 |quote=1. the past, present, and future regarded as a continuous whole. . . .  2. (Physics) a quantity measuring duration, measured with reference to the rotation of the earth or from the vibrations of certain atoms}}
* {{cite web |url=http://www.britannica.com/EBchecked/topic/596034/time |title=Britannica Concise Encyclopedia |year=2010 |quote=Measured or measurable period. More broadly, it is a continuum that lacks spatial dimensions.}}
</ref> Temporis mensurae unitas in [[Systema Internationalis|Systemate Internationali]] (seu S.I.) definita [[secundum]] est littera ''s'' [[abbreviatio|abbreviatum]].

Tempus antiquitus intellegitur dimensio esse in qua eventa ordinantur, ut quodam modo futura a praeteritis discernantur. Quia autem [[physica]]e [[Scientia (ratio)|scientia]] exactam temporis definitionem requirit, temporis definitio novis theoriis excogitatis mutata est. Cum vulgus [[horologium]] parvum satis habet ad temporis mensuram, physici atomicis horologiis saepe utuntur, non solum quia atomica horologia optima sunt, sed etiam quia tempus [[atomus|atomicis]] transitionibus definitur. <!--Hoc modo tempus mensi sunt physici similibus praeceptis in laboratoribus per totum orbem terrarum dispersis. = ??? --> 

Tempus saepe indicatur per ''s'' ([[secundum|secunda]]), ''min'' ([[minutum|minuta]]), ''h'' ([[hora]]s), ''d'' ([[dies]]), ''a'' ([[annus|annos]]).

== Historia ==
Constat [[philosophus|philosophos]] Graecos de temporis natura valde cogitasse. [[Paradoxum Zenonis]] est praeclarissimum exemplum quod tempus semper exspectationem hominum movit.

[[Isaacus Newtonus|Newtoni]] aevo, [[scientia (ratio)|scientia]] tempus nondum accurate definiebat, sicut in scholio primo libri a Newtono scripti ''[[Philosophiae naturalis principia mathematica]]''<ref name="Newton">Isaacus Newtonus, ''Philosophiae Naturalis Principia Mathematica'', editio prima, 1687</ref> (pg. 5 editionis primae, [[1687]]) legitur:
:Nam tempus, spatium, locum et motum ut omnibus notissima non definio.
Nihilominus in sententiis quae secutae sunt has observationes facit:
:Dicam tamen quod vulgus quantitates hasce non aliter quam ex relatione ad sensibilia concipit. Et inde oriuntur praejudicia quaedam, quibus tollendis convenit easdem in absolutas & relativas, veras & apparentes, Mathematicas et vulgares distingui.
Tunc, praeclarissima sequitur sententia '''tempus''' statuens '''absolutum''', quae anno [[1905]] ab [[Albertus Einstein|Einstein]] abrogata est:
: {{tpe|I}} Tempus absolutum verum & Mathematicum, in se & natura sua absq; relatione ad externum quodvis, aequabiliter fluit, alioq; nomine dicitur Duratio; relativum apparens & vulgare est sensibilis & externa quaevis Durationis per motum mensura, (seu accurata seu inaequabilis) qua vulgus vice veri temporis utitur; ut Hora, Dies, Mensis, Annus.

Haec definitio temporis esse vera omnibus usque ad annum [[1905]] videbatur. Einstein autem, de [[celeritas luminis|celeritate luminis]] cogitans, recte intellexit tempus (et spatium) non esse absolutum sed relativum. Dehinc, post complures computationes, theoriam [[relativitas specialis|relativitatis specialis]] proposuit, quae [[spatium|spatii]] temporisque comprehensionem secundum scientiam physicam magnopere mutavit. Theoria [[relativitas generalis|relativitatis generalis]] eius, anno [[1915]] excogitata, connectionem inter tempus spatiumque et relativam eorum naturam patefecit. Demum theoriae relativitatis praecepta circa tempus spatiumque facta sunt veritates quibus omne [[experimentum]] adhuc obtemperavit, atque multa sunt exempla de natura relativa temporis.

== Tempus secundum relativitatis theoriam ==

=== Relativitas specialis ===
Secundum [[relativitas specialis|Relativitatis Specialis]] theoriam, temporis definitio ex ''simultaneitatis'' concepto originem habet. Non unum ''tempus absolutum'' est, quemadmodum Newtonus cogitavit, quia constantia [[celeritas luminis|celeritatis luminis]] obtemperata, tempus ex inertialibus referentialibus pendet, sicut ab [[Albertus Einstein|Einstein]] anno [[1905]] demonstratus est. Duo autem homines dissimiles [[velocitas|velocitates]] habentes unus cum alio non consentiunt circa temporis durationem. Manifestum est hanc affirmationem esse contrariam ei qua a [[Isaacus Newtonus|Newtono]] scripta est, sicut in ''Principia'' (p. 7) legitur:
:Accelerari & retardari possunt motus omnes, sed fluxus Temporis absoluti mutari nequit. Eadem est duratio seu perseverantia existentiae rerum, sive motus sint celeres, sive tardi, sive nulli.

Mathematicas aequationes usum faciendo, temporis durationem ex duobus hominibus mensuratam non eandem esse expedite comprobare possumus, si velocitates quibus illi se movent dissimiles sint. Facilior intelligendae causa, sit <math> \Delta t_0 </math> temporis duratio sive intervallum quam Carolus, qui nullam velocitatem habet, horologio suo metitur (hoc tempus est saepe a [[physicus|physicis]] vocatum ''tempus proprium''). Si autem Iosephus velocitatem <math>v</math> habet (secundum Caroli referentialem) sequitur ut intervallum <math> \Delta t_1 </math> ab Iosepho mensuratum est,
:<math> \Delta t_1 = \Delta t_0\sqrt{1-\frac{v^2}{c^2}}</math>
unde ''c'' [[celeritas luminis|celeritatem luminis]] denotat. Ex quo sequitur ut tempus ab Iosepho mensuratus minor quam Caroli tempus est. Hoc est praeclarissimus '''temporis dilatatio''' effectus, qui usque ad hodie vulgi comprehensionem excitat.

=== Relativitas generalis ===
Einstein anno [[1915]], quando [[relativitas generalis|relativitatis generalis]] theoriam excogitavit, temporis comprehensionem rursus mutavit. Non solum spectatoris relativa [[velocitas]] temporis fluxum mutat sed etiam [[acceleratio]]. Rustice relativitas generalis afirmat quod accelerans spectator minus senescit quam maior est eius [[acceleratio]]. Deinde, post accelerationem cum campo gravitationalis identificare (''Equivalentiae Principium''), 
temporis fluxum prope [[massa|massiva]] corpora esse lentior recte conclusit. 

Sit, exempli gratia, spectator super [[planeta]]m sphericum radium ''r'' atque massam ''M'' habentem. Hic spectator temporis intervallum <math> \Delta t_0 </math> metitur. Si <math> \Delta t_1 </math> temporis durationem mensuratam a maxime distante homine (i.e. <math>r\to\infty</math>) denotat tunc mathematice sequitur quod inter eas relatio est
:<math> \Delta t_0 = \Delta t_1\sqrt{1-\frac{2GM}{rc^2}}</math>
unde <math>G</math> est Newtoni constans.

{{NexInt}}
{{div col|3}}
* [[Aeternitas]]
* [[Cronus]]
* [[Chronologia]]
* [[Chronosophia]]
* [[Horologium]]
* [[Index magnitudinum physicarum]]
* [[Iter transtemporale]]
* [[Numerus circadianus]]
* [[Philosophia spatii et temporis]]
* [[Praeteritum (grammatica)]]
* [[Reditus aeternus]]
* [[Sagitta temporis]]
* [[Synechismus]]
* [[Temporalitas]]
* [[Tempus aestivum]]
* [[Tempus (ars grammatica)]]
* [[Tempus Atomicum Internationale]]
* [[Ungleichzeitigkeit]]
{{div col end}}

== Notae ==
<references />

== Fontes ==
* Isaacus Newtonus, ''Philosophiae Naturalis Principia Mathematica'', editio prima, 1687
* [http://dibinst.mit.edu/BURNDY/Collections/Babson/OnlineNewton/Principia.htm ''Philosophiae naturalis principia mathematica''] (omne opus in forma .pdf)
* [http://www.dmoz.org/Reference/Time/ Tempus apud "Open Directory"]
* [http://www.nmm.ac.uk/harrison Regium Observatorium et historia astronomiae: John Harrison et quaestio longitudinis]

=== Perceptio temporis ===
* [https://web.archive.org/web/20070930072044/http://manchestertiming.co.uk/ Studia de perceptione temporis apud Universitatem Mancuniensem]

=== Physica ===
* [https://web.archive.org/web/19970729054246/http://physics.nist.gov/GenInt/Time/world.html Ambulatio per tempus]
* [http://www.newscientist.com/article/dn16607-seven-things-you-need-to-know-about-time.html Septem Res Tibi Necesse Est Scire De Tempore]

=== Philosophia ===
;'''Philosophia orientalis'''
* [http://www.literati-tradition.com/time.html Schema Conceptualis Cogitationis Sinensis de Philosophiae: Tempus]
* [https://web.archive.org/web/20100805074616/http://www.beyondthemind.net/time.html Menda in Mente: Inventio Temporis]

;'''Philosophia Occidentalis'''
* {{cite web
|url=http://www.onphilosophy.co.uk/time_-_a_dialogue.html
|title=Is there a defensible argument for the non-existence of time?
|first=Will
|last=Crouch
|Copyright James Nicholson
|year=2006-2008
|work=On Philosophy}}
* {{cite encyclopedia
|url=http://www.iep.utm.edu/t/time.htm
|title=Time
|first=Bradley (California State University, Sacramento)
|last=Dowden
|year=2007
|encyclopedia=The Internet Encyclopedia of Philosophy
|editor=James Fieser, Ph.D., Bradley Dowden, Ph.D.}}
* {{Stanford|http://plato.stanford.edu/archives/win2004/entries/time-experience|The Experience and Perception of Time|Robin Le Poidevin|2004}}
* {{Stanford|http://plato.stanford.edu/archives/win2007/entries/leibniz-physics/|Leibniz's Philosophy of Physics|Jeff Mcdonough|2007}}
* {{cite web
|url=http://www.friesian.com/space.htm#clarke
|title=The Clarke-Leibniz Debate (1715-1716)
|first=Kelley L., Ph.D. (Los Angeles Valley College)
|last=Ross
|publisher=The Proceedings of the Friesian School, Fourth Series (1996, 1999, 2001)}}
* {{cite web
|url=http://www.friesian.com/space.htm#kant
|title=Three Points in Kant's Theory of Space and Time
|first=Kelley L., Ph.D. (Los Angeles Valley College)
|last=Ross
|publisher=The Proceedings of the Friesian School, Fourth Series (1996, 1999, 2001)}}
* {{Stanford|http://plato.stanford.edu/entries/spacetime-bebecome/|Being and Becoming in Modern Physics|Steven Savitt|2007}}
* {{Stanford|http://plato.stanford.edu/archives/sum2004/entries/kant-leibniz/|Kant and Leibniz|Catherine Wilson|2004}}

=== Conservatio temporis ===
* [http://tycho.usno.navy.mil/systime.html Systemata varia temporis mensi]
* [http://www1.bipm.org/en/scientific/tai/time_server.html UTC/TAI Timeserver]
* [http://news.bbc.co.uk/2/hi/science/nature/3486160.stm Commentarius BBC de minimo tempore menso]
* [http://www.fhs.ch/en/ Foederatio Industriae "Swiss Watch"]
* [http://www.awi-net.org American Watchmakers-Clockmakers Institute]
* [http://www.nawcc.org National Association of Watch & Clock Collectors]

=== Miscellanea ===
* [http://exploringtime.org/?page=segments Tempus Exploratum] a Tempore Planck ad vitam universi
* [http://www.studyoftime.org/ Societas Internationalis pro Studio Temporis]

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