Temporal finitism

Temporal finitism is the doctrine that time is finite in the past. The philosophy of Aristotle, expressed in such works as his Physics, held that although space was finite, with only void existing beyond the outermost sphere of the heavens, time was infinite. This caused problems for mediaeval Islamic, Jewish, and Christian philosophers, who were unable to reconcile the Aristotelian conception of the eternal with the Genesis creation narrative.[1]

Modern cosmogony accepts finitism, in the form of the Big Bang, rather than Steady State theory which allows for a universe that has existed for an infinite amount of time, but on physical rather than philosophical grounds.

Medieval background

In contrast to ancient Greek philosophers who believed that the universe had an infinite past with no beginning, medieval philosophers and theologians developed the concept of the universe having a finite past with a beginning. This view was inspired by the creation myth shared by the three Abrahamic religions: Judaism, Christianity and Islam.[2]

Prior to Maimonides, it was held that it was possible to prove, philosophically, creation theory. The Kalam cosmological argument held that creation was provable, for example. Maimonides himself held that neither creation nor Aristotle's infinite time were provable, or at least that no proof was available. (According to scholars of his work, he didn't make a formal distinction between unprovability and the simple absence of proof.) Thomas Aquinas was influenced by this belief, and held in his Summa Theologica that neither hypothesis was demonstrable. Some of Maimonides' Jewish successors, including Gersonides and Crescas, conversely held that the question was decidable, philosophically.[3]

John Philoponus was probably the first to use the argument that infinite time is impossible in order to establish temporal finitism. He was followed by many others including St. Bonaventure.

Philoponus' arguments for temporal finitism were severalfold. Contra Aristotlem has been lost, and is chiefly known through the citations used by Simplicius of Cilicia in his commentaries on Aristotle's Physics and De Caelo. Philoponus' refutation of Aristotle extended to six books, the first five addressing De Caelo and the sixth addressing Physics, and from comments on Philoponus made by Simplicius can be deduced to have been quite lengthy.[4]

A full exposition of Philoponus' several arguments, as reported by Simplicius, can be found in Sorabji.[5]

One such argument was based upon Aristotle's own theorem that there were not multiple infinities, and ran as follows: If time were infinite, then as the universe continued in existence for another hour, the infinity of its age since creation at the end of that hour must be one hour greater than the infinity of its age since creation at the start of that hour. But since Aristotle holds that such treatments of infinity are impossible and ridiculous, the world cannot have existed for infinite time.

The most sophisticated medieval arguments against an infinite past were later developed by the early Muslim philosopher, Al-Kindi (Alkindus); the Jewish philosopher, Saadia Gaon (Saadia ben Joseph); and the Muslim theologian, Al-Ghazali (Algazel). They developed two logical arguments against an infinite past, the first being the "argument from the impossibility of the existence of an actual infinite", which states:[6]

"An actual infinite cannot exist."
"An infinite temporal regress of events is an actual infinite."
"Thus an infinite temporal regress of events cannot exist."

This argument depends on the (unproved) assertion that an actual infinite cannot exist; and that an infinite past implies an infinite succession of "events", a word not clearly defined. The second argument, the "argument from the impossibility of completing an actual infinite by successive addition", states:[2]

"An actual infinite cannot be completed by successive addition."
"The temporal series of past events has been completed by successive addition."
"Thus the temporal series of past events cannot be an actual infinite."

The first statement states, correctly, that a finite (number) cannot be made into an infinite one by the finite addition of more finite numbers. The second skirts around this; the analogous idea in mathematics, that the (infinite) sequence of negative integers "..-3, -2, -1" may be extended by appending zero, then one, and so forth; is perfectly valid.

Both arguments were adopted by later Christian philosophers and theologians, and the second argument in particular became more famous after it was adopted by Immanuel Kant in his thesis of the first antinomy concerning time.[2]

Modern revival

Immanuel Kant's argument for temporal finitism, at least in one direction, from his First Antinomy, runs as follows:[7][8]

If we assume that the world has no beginning in time, then up to every given moment an eternity has elapsed, and there has passed away in that world an infinite series of successive states of things. Now the infinity of a series consists in the fact that it can never be completed through successive synthesis. It thus follows that it is impossible for an infinite world-series to have passed away, and that a beginning of the world is therefore a necessary condition of the world's existence.

— Immanuel Kant, First Antinomy, of Space and Time

Modern mathematics generally incorporates infinity. For most purposes it is simply used as convenient; when considered more carefully it is incorporated, or not, according to whether the axiom of infinity is included. This is the mathematical concept of infinity; while this may provide useful analogies or ways of thinking about the physical world, it says nothing directly about the physical world. Georg Cantor recognized two different kinds of infinity. The first, used in calculus, he called the variable finite, or potential infinite, represented by the sign (known as the lemniscate), and the actual infinite, which Cantor called the "true infinite." His notion of transfinite arithmetic became the standard system for working with infinity within set theory. David Hilbert thought that the role of the actual infinite was relegated only to the abstract realm of mathematics. "The infinite is nowhere to be found in reality. It neither exists in nature nor provides a legitimate basis for rational thought... The role that remain for the infinite to play is solely that of an idea."[9] Philosopher William Lane Craig argues that if the past were infinitely long, it would entail the existence of actual infinites in reality.[10]

Craig and Sinclair also argue that an actual infinite cannot be formed by successive addition. Quite independent of the absurdities arising from an actual infinite number of past events, the formation of an actual infinite has its own problems. For any finite number n, n+1 equals a finite number. An actual infinity has no immediate predecessor.[11]

The Tristram Shandy paradox is an attempt to illustrate the absurdity of an infinite past. Imagine Tristram Shandy, an immortal man who writes his biography so slowly that for every day that he lives, it takes him a year to record that day. Suppose that Shandy had always existed. Since there is a one-to-one correspondence between the number of past days and the number of past years on an infinite past, one could reason that Shandy could write his entire autobiography.[12] From another perspective, Shandy would only get farther and farther behind, and given a past eternity, would be infinitely far behind.[13]

Craig asks us to suppose that we met a man who claims to have been counting down from infinity and is now just finishing. We could ask why he did not finish counting yesterday or the day before, since eternity would have been over by then. In fact for any day in the past, if the man would have finished his countdown by day n, he would have finished his countdown by n-1. It follows that the man could not have finished his countdown at any point in the finite past, since he would have already been done.[14]

Input from physicists

In 1984 physicist Paul Davies deduced a finite-time origin of the universe in a quite different way, from physical grounds: "the universe will eventually die, wallowing, as it were, in its own entropy. This is known among physicists as the 'heat death' of the universe... The universe cannot have existed for ever, otherwise it would have reached its equilibrium end state an infinite time ago. Conclusion: the universe did not always exist."[15]

More recently though physicists have proposed various ideas for how the universe could have existed for an infinite time, such as eternal inflation. But in 2012, Alexander Vilenkin and Audrey Mithani of Tufts University wrote a paper claiming that in any such scenario past time could not have been infinite.[16] It could however have been "before any nameable time", according to Leonard Susskind.[17]

Critical reception

Kant's argument for finitism has been widely discussed, for instance Jonathan Bennett[18] points out that Kant's argument is not a sound logical proof: His assertion that "Now the infinity of a series consists in the fact that it can never be completed through successive synthesis. It thus follows that it is impossible for an infinite world-series to have passed away", assumes that the universe was created at a beginning and then progressed from there, which seems to assume the conclusion. A universe that simply existed and had not been created, or a universe that was created as an infinite progression, for instance, would still be possible. Bennett quotes Strawson:

"A temporal process both completed and infinite in duration appears to be impossible only on the assumption that it has a beginning. If ... it is urged that we cannot conceive of a process of surveying which does not have a beginning, then we must inquire with what relevance and by what right the notion of surveying is introduced into the discussion at all."

Some of the criticism of William Lane Craig's argument for temporal finitism has been discussed and expanded on by Stephen Puryear.[19][20]

In this, he writes Craig's argument as:

  1. If the universe did not have a beginning, then the past would consist in an infinite temporal sequence of events.
  2. An infinite temporal sequence of past events would be actually and not merely potentially infinite.
  3. It is impossible for a sequence formed by successive addition to be actually infinite.
  4. The temporal sequence of past events was formed by successive addition.
  5. Therefore, the universe had a beginning.

Puryear points out that Aristotle and Aquinas had an opposing view to point 2, but that the most contentious is point 3. Puryear says that many philosophers have disagreed with point 3, and adds his own objection:

"Consider the fact that things move from one point in space to another. In so doing, the moving object passes through an actual infinity of intervening points. Hence, motion involves traversing an actual infinite ... Accordingly, the finitist of this stripe must be mistaken. Similarly, whenever some period of time elapses, an actual infinite has been traversed, namely, the actual infinity of instants that make up that period of time."

Puryear then points that Craig has defended his position by saying that time might or must be naturally divided and so there is not an actual infinity of instants between two times. Puryear then goes on to argue that if Craig is willing to turn an infinity of points into a finite number of divisions, then points 1, 2 and 4 are not true.

An article by Louis J. Swingrover makes a number of points relating to the idea that Craig's "absurdities" are not contradictions in themselves: they are all either mathematically consistent (like Hilbert's hotel or the man counting down to today), or do not lead to inescapable conclusions. He argues that if one makes the assumption that any mathematically coherent model is metaphysically possible, then it can be shown that an infinite temporal chain is metaphysically possible, since one can show that there exist mathematically coherent models of an infinite progression of times. He also says that Craig might be making a cardinality error similar to assuming that because an infinitely extended temporal series would contain an infinite number of times, then it would have to contain the number "infinity".

Quentin Smith[21] attacks "their supposition that an infinite series of past events must contain some events separated from the present event by an infinite number of intermediate events, and consequently that from one of these infinitely distant past events the present could never have been reached".

Smith asserts that Craig and Wiltrow are making a cardinality error by confusing an unending sequence with a sequence whose members must be separated by an infinity: None of the integers is separated from any other integer by an infinite number of integers, so why assert that an infinite series of times must contain a time infinitely far back in the past.

Smith then says that Craig uses false presuppositions when he makes statements about infinite collections (in particular the ones relating to Hilbert's Hotel and infinite sets being equivalent to proper subsets of them), often based on Craig finding things "unbelievable", when they are actually mathematically correct. He also points out that the Tristram Shandy paradox is mathematically coherent, but some of Craig's conclusions about when the biography would be finished are incorrect.

Ellery Eells[22] expands on this last point by showing that the Tristram Shandy paradox is internally consistent and fully compatible with an infinite universe.

Graham Oppy[23] embroiled in debate with Oderberg, points out that the Tristram Shandy story has been used in many versions. For it to be useful to the temporal finitism side, a version must be found that is logically consistent and not compatible with an infinite universe. To see this, note that the argument runs as follows:

  1. If an infinite past is possible, then the Tristram Shandy story must be possible
  2. The Tristram Shandy story leads to contradiction.
  3. Therefore, an infinite past is not possible.

The problem for the finitist is that point 1 is not necessarily true. If a version of the Tristram Shandy story is internally inconsistent, for instance, then the infinitist could just assert that an infinite past is possible, but that particular Tristram Shandy is not because it's not internally consistent. Oppy then lists the different versions of the Tristram Shandy story that have been put forward and shows that they are all either internally inconsistent or they don't lead to contradiction.


  1. ^ Feldman 1967, pp. 113-37.
  2. ^ a b c Craig 1979.
  3. ^ Feldman 1967.
  4. ^ Davidson 1969.
  5. ^ Sorabji 2005.
  6. ^ Craig 1979, pp. 165-66.
  7. ^ Viney 1985, pp. 65-68.
  8. ^ Smith 1929, A 426.
  9. ^ Benacerraf & Putnam 1991, p. 151.
  10. ^ Craig & Sinclair 2009, p. 115.
  11. ^ Craig & Sinclair 2009, p. 117.
  12. ^ Russell 1937, p. 358.
  13. ^ Craig & Sinclair 2009, p. 121.
  14. ^ Craig & Sinclair 2009, p. 122.
  15. ^ Davies 1984, p. 11.
  16. ^ Audrey Mithani and Alexander Vilenkin (Apr 20, 2012). "Did the universe have a beginning?". arXiv:1204.4658 [hep-th].
  17. ^ Marcus Chown (Dec 1, 2012). "Before the big bang: something or nothing". New Scientist.
  18. ^ Bennett 1971.
  19. ^ Puryear 2014.
  20. ^ http:/www.ncsu.edu/~smpuryea/papers/FinitismBeginningUniverse.pdf FINITISM AND THE BEGINNING OF THE UNIVERSE -- Preprint
  21. ^ Smith 1987.
  22. ^ Eells 1988.
  23. ^ Oppy 2003.


  • Benacerraf, Paul; Putnam, Hilary (1991). Philosophy of Mathematics: Selected Readings (2nd ed.). Cambridge University Press.
  • Bennett, Jonathan (1971). "The age and size of the world". Synthese. 23 (1): 127–46. doi:10.1007/bf00414149.
  • Craig, W. L. (1979). "Whitrow and Popper on the Impossibility of an Infinite Past". The British Journal for the Philosophy of Science. 30 (2): 165–70. doi:10.1093/bjps/30.2.165.
  • Craig, W. L.; Sinclair, J. D. (2009). "The kalam cosmological argument". In Craig, W. L.; Moreland, J. P. (eds.). The Blackwell Companion to Natural Theology. Wiley-Backwell. pp. 101–201.
  • Davidson, H. A. (1969). "John Philoponus as a Source of Medieval Islamic and Jewish Proofs of Creation". Journal of the American Oriental Society. 89 (2): 357–91. doi:10.2307/596519. JSTOR 596519.
  • Davies, Paul (1984). God and the New Physics. Simon & Schuster.
  • Eells, Ellery (1988). "Quentin Smith on Infinity and the past". Philosophy of Science. 55 (3): 453–55. doi:10.1086/289451.
  • Feldman, Seymour (1967). "Gersonides' Proofs for the Creation of the Universe". Proceedings of the American Academy for Jewish Research. 35: 113–37. doi:10.2307/3622478. JSTOR 3622478.
  • Oppy, Graham (2003). "From the Tristram Shandy Paradox to the Christmas Shandy Paradox". Ars Disputandi. 3 (1): 172–95. doi:10.1080/15665399.2003.10819784.
  • Puryear, Stephen (2014). "Finitism and the Beginning of the Universe". Australasian Journal of Philosophy. 92 (4): 619–29. doi:10.1080/00048402.2014.949804.
  • Russell, Bertrand (1937). The Principles of Mathematics (2nd ed.). George Allen.
  • Smith, N. K. (1929). Immanuel Kant's Critique Of Pure Reason. Macmillan.
  • Smith, Quentin (1987). "Infinity and the Past". Philosophy of Science. 54 (1): 63–75. doi:10.1086/289353.
  • Sorabji, Richard (2005). "Did the Universe have a Beginning?". The Philosophy of the Commentators, 200–600 AD. Cornell University Press. pp. 175–88.
  • Viney, D. W. (1985). "The Cosmological Argument". Charles Hartshorne and the Existence of God. SUNY Press. pp. 59–76.

Further reading

  • Bunn, Robert (1988). "Review of Time, Creation, and the Continuum: Theories in Antiquity and the Early Middle Ages by Richard Sorabji". Philosophy of Science. 55 (2): 304–306. doi:10.1086/289436.
  • Craig, W. L. (2000). The Kalām Cosmological Argument. Wipf and Stock Publishers.
  • Draper, Paul (2007). "A Critique of the Kalām Cosmological Argument". In Pojman, Louis P.; Rea, Michael (eds.). Philosophy of Religion: An Anthology (5th ed.). Cengage Learning. pp. 45–51.
  • Moore, A. W. (2001). "Medieval and Renaissance Thought". The Infinite. Routledge. pp. 46–49.
  • Sorabji, Richard (2006). Time, Creation and the Continuum (Paperback ed.). University of Chicago Press.
  • Waters, B. V. (2013). "Methuselah's Diary and the Finitude of the Past" (PDF). Philosophia Christi. 15 (2): 463–469. doi:10.5840/pc201315240.
  • Waters, B. V. (2015). "Toward a new kalām cosmological argument". Cogent Arts and Humanities. 2 (1): 1–8. doi:10.1080/23311983.2015.1062461.
  • White, M. J. (1992). "Aristotle on Time and Locomotion". The Continuous and the Discrete: Ancient Physical Theories from a Contemporary Perspective. Oxford University Press.
A series and B series

In philosophy, A series and B series are two different descriptions of the temporal ordering relation among events. The two series differ principally in their use of tense to describe the temporal relation between events. The terms were introduced by the Scottish idealist philosopher John McTaggart in 1908 as part of his argument for the unreality of time, but since then they have become widely used terms of reference in modern discussions of the philosophy of time.


An astrarium, also called a planetarium, is the mechanical representation of the cyclic nature of astronomical objects in one timepiece. It is an astronomical clock.

BPL (time service)

BPL is the call sign of the official long-wave time signal service of the People's Republic of China, operated by the Chinese Academy of Sciences, broadcasting on 100 kHz from CAS's National Time Service Center in Pucheng County, Shaanxi at 34°56′54″N 109°32′34″E, roughly 70 km northeast of Lintong, along with NTSC's short-wave time signal BPM on 2.5, 5.0, 10.0, and 15.0 MHz.

BPL broadcasts LORAN-C compatible format signal from 5:30 to 13:30 UTC, using an 800 kW transmitter covering a radius up to 3000 km.


Chronometry (from Greek χρόνος chronos, "time" and μέτρον metron, "measure") is the science of the measurement of time, or timekeeping. Chronometry applies to electronic devices, while horology refers to mechanical devices.

It should not to be confused with chronology, the science of locating events in time, which often relies upon it.

Clock position

A clock position is the relative direction of an object described using the analogy of a 12-hour clock to describe angles and directions. One imagines a clock face lying either upright or flat in front of oneself, and identifies the twelve hour markings with the directions in which they point.

Using this analogy, 12 o'clock means ahead or above, 3 o'clock means to the right, 6 o'clock means behind or below, and 9 o'clock means to the left. The other eight hours refer to directions that are not directly in line with the four cardinal directions.

In aviation, a clock position refers to a horizontal direction; it may be supplemented with the word high or low to describe the vertical direction which is pointed towards your feet. 6 o'clock high means behind and above the horizon, while 12 o'clock low means ahead and below the horizon.

Common year

A common year is a calendar year with 365 days, as distinguished from a leap year, which has 366. More generally, a common year is one without intercalation. The Gregorian calendar, (like the earlier Julian calendar), employs both common years and leap years to keep the calendar aligned with the tropical year, which does not contain an exact number of days.

The common year of 365 days has 52 weeks and one day, hence a common year always begins and ends on the same day of the week (for example, January 1 and December 31 fell on a Sunday in 2017) and the year following a common year will start on the subsequent day of the week. In common years, February has four weeks, so March will begin on the same day of the week. November will also begin on this day.

In the Gregorian calendar, 303 of every 400 years are common years. By comparison, in the Julian calendar, 300 out of every 400 years are common years, and in the Revised Julian calendar (used by Greece) 682 out of every 900 years are common years.

Cosmology in medieval Islam

Islamic cosmology is the cosmology of Islamic societies. It is mainly derived from the Qur'an, Hadith, Sunnah, and current Islamic as well as other pre-Islamic sources. The Qur'an itself mentions seven heavens.


Endurantism or endurance theory is a philosophical theory of persistence and identity. According to the endurantist view, material objects are persisting three-dimensional individuals wholly present at every moment of their existence, which goes with an A-theory of time. This conception of an individual as always present is opposed to perdurantism or four dimensionalism, which maintains that an object is a series of temporal parts or stages, requiring a B-theory of time. The use of "endure" and "perdure" to distinguish two ways in which an object can be thought to persist can be traced to David Lewis.


Eternity in common parlance is an infinitely long period of time. In classical philosophy, however, eternity is defined as what exists outside time while sempiternity is the concept that corresponds to the colloquial definition of eternity.

Eternity is an important concept in many religions, where the god or gods are said to endure eternally. Some, such as Aristotle, would say the same about the natural cosmos in regard to both past and future eternal duration, and like the eternal Platonic forms, immutability was considered essential.

Event (philosophy)

In philosophy, events are objects in time or instantiations of properties in objects.


HD2IOA is the callsign of a time signal radio station operated by the Navy of Ecuador. The station is located at Guayaquil, Ecuador and transmits in the HF band on 3.81 and 7.6 MHz.The transmission is in AM mode with only the lower sideband (part of the time H3E and the rest H2B/H2D) and consists of 780 Hz tone pulses repeated every ten seconds and voice announcements in Spanish.

While sometimes this station is described as defunct, reception reports of this station on 3.81 MHz appear regularly at the Utility DX Forum.

Hexadecimal time

Hexadecimal time is the representation of the time of day as a hexadecimal number in the interval [0,1).

The day is divided into 1016 (1610) hexadecimal hours, each hour into 10016 (25610) hexadecimal minutes, and each minute into 1016 (1610) hexadecimal seconds.

History of the Big Bang theory

The history of the Big Bang theory began with the Big Bang's development from observations and theoretical considerations. Much of the theoretical work in cosmology now involves extensions and refinements to the basic Big Bang model.


The minute is a unit of time or angle. As a unit of time, the minute is most of times equal to ​1⁄60 (the first sexagesimal fraction) of an hour, or 60 seconds. In the UTC time standard, a minute on rare occasions has 61 seconds, a consequence of leap seconds (there is a provision to insert a negative leap second, which would result in a 59-second minute, but this has never happened in more than 40 years under this system). As a unit of angle, the minute of arc is equal to ​1⁄60 of a degree, or 60 seconds (of arc). Although not an SI unit for either time or angle, the minute is accepted for use with SI units for both. The SI symbols for minute or minutes are min for time measurement, and the prime symbol after a number, e.g. 5′, for angle measurement. The prime is also sometimes used informally to denote minutes of time.


Perdurantism or perdurance theory is a philosophical theory of persistence and identity. The perdurantist view is that an individual has distinct temporal parts throughout its existence. Perdurantism is usually presented as the antipode to endurantism, the view that an individual is wholly present at every moment of its existence.The use of "endure" and "perdure" to distinguish two ways in which an object can be thought to persist can be traced to David Kellogg Lewis (1986). However, contemporary debate has demonstrated the difficulties in defining perdurantism (and also endurantism). For instance, the work of Ted Sider (2001) has suggested that even enduring objects can have temporal parts, and it is more accurate to define perdurantism as being the claim that objects have a temporal part at every instant that they exist. Currently there is no universally acknowledged definition of perdurantism. Others argue that this problem is avoided by creating time as a continuous function, rather than a discrete one.

Perdurantism is also referred to as "four-dimensionalism" (by Ted Sider, in particular) but perdurantism also applies if one believes there are temporal but non-spatial abstract entities (like immaterial souls or universals of the sort accepted by David Malet Armstrong).

Philosophical presentism

Philosophical presentism is the view that neither the future nor the past exist. In some versions of presentism, this view is extended to timeless objects or ideas (such as numbers). According to presentism, events and entities that are wholly past or wholly future do not exist at all. Presentism contrasts with eternalism and the growing block theory of time which hold that past events, like the Battle of Waterloo, and past entities, like Alexander the Great's warhorse Bucephalus, really do exist, although not in the present. Eternalism extends to future events as well.

Static interpretation of time

The static interpretation of time is a view of time which arose in the early years of the 20th century from Einstein's special relativity and Hermann Minkowski's extension of special relativity in which time and space were famously united in physicists' thinking as spacetime.

Essentially the universe is regarded as akin to a reel of film – which is a wholly static physical object – but which when played through a movie projector conjures a world of movement, color, light and change. In the static view our whole universe – our past, present, and future are fixed parts of that reel of film, and the projector is our consciousness. But the 'happenings' of our consciousness have no objective significance – the objective universe does not happen, it simply exists in its entirety, albeit perceived from within as a world of changes.

The alternative, and commonly assumed view, is that the world unfolds in existence, that our present has some wider physical significance, because the universe evolves in step with it.

The static view is the simpler in that all that is held to exist is the physical ordering of the universe. All that there is at every time simply exists. The unfolding view requires an additional quality to the universe – that besides the physical ordering there is some quality of coming into and out of existence.

One can argue that the onus is therefore upon those who propose it, that the world unfolds, and that this additional quality they hold to (absent from special relativity) is indeed a physical feature of the world. There is however as yet no proof, experiment, or measurement, to show that our conscious experience of an unfolding present has any objective physical significance, or that the universe is anything other than static.

The static view is however commonly rejected for psychological, not scientific reasons, because it leads to a fatalistic or "fixed" conclusion about human existence – our 'past', 'present', and 'future' being what they are – there is no contingency in the world and no possibility of 'altering' or creating the future through some act of will – the future exists. It is simply that our consciousness has not yet reached it.

Tomorrow (time)

Tomorrow is a temporal construct of the relative future; literally of the day after the current day (today), or figuratively of future periods or times. Tomorrow is usually considered just beyond the present and counter to yesterday. It is important in time perception because it is the first direction the arrow of time takes humans on Earth.


YVTO is the callsign of the official time signal from the Juan Manuel Cagigal Naval Observatory in Caracas, Venezuela. The content of YVTO's signal, which is a continuous 1 kW amplitude modulated carrier wave at 5.000 MHz, is much simpler than that broadcast by some of the other time signal stations around the world, such as WWV.

The methods of time transmission from YVTO are very limited. The broadcast employs no form of digital time code. The time of day is given in Venezuelan Standard Time (VET), and is only sent using Spanish language voice announcements. YVTO also transmits 100 ms-long beeps of 1000 Hz every second, except for thirty seconds past the minute. The top of the minute is marked by a 0.5 second 800 Hz tone.The station previously broadcast on 6,100 MHz but appears to have changed to the current frequency by 1990.

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