Cyclical dynamics are ubiquitous in the universe with spatial/temporal extents varying over many orders of magnitude. Each dynamical structure has its own tempo and is likely to be a consonance of many varying sub-system tempos. We select a certain, extremely rarefied atomic frequency to ground our SI time unit upon the underlying physical reality. Thus, any temporal measurement of a dynamical system is referential to a highly unique clockwork tempo that is currently accurate to one second in some billions of years. Question: Does this practice project upon our mechanics a clockwork regularity that is not in fact actual? Does it create the illusion of a universe in which every part moves in phase with interlocked regularity? Alternatively, and more attractively to me, if the depth of distinction between entities bestows upon them their own clockwork which governs their turnings, then, particularly with more complexly organized entitles, any interaction between them creates the possibility of an eureka moment in which a new future path may be created. Which is the case? This question may be better stated and perhaps lies more in the realm of physics, but we are reminded that philosophy has long played the role of elder sibling to physics and been helpful in its refinement. Attached: Photo of entity – Bubble of exhaled air in water.

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    You'll get a better technical response in PhysicsSE. Newtonian absolute time was replaced by relativistic time in which time dilates between extensions of space moving at different speeds. A simple intuitive proof can be done with trigonometric vectors.
    – J D
    Nov 16, 2021 at 0:43
  • Can't seem to add a jpeg picture because body disappears when I do.
    – Don Foster
    Nov 16, 2021 at 0:44
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    For organisms moving at different times, read up on the twins paradox.
    – J D
    Nov 16, 2021 at 0:46
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    According to modern physics, no. Even physical time is relative, not to entities' own clockwork, but to their reference frames. There are "internal clocks" in biological organisms known as circadian rhythms, and even philosophical conceptions of subjective/phenomenal "time", e.g. Bergson's duration. But it is unclear why someone needs an "individual clock" to "create new future paths", universal clock would do just as well.
    – Conifold
    Nov 16, 2021 at 0:52
  • Thanks for considerations here.
    – Don Foster
    Nov 16, 2021 at 15:51

5 Answers 5


I think that the answer to this is basically a clear 'no'.

Post special relativity* - think of clocks as like odometers, they measure what is called 'proper time' along the trajectory that they are moving; this is basically an interval between two events in spacetime (an event being a spacetime equivalent of a point). There is no defined meaning to the idea of an absolute simultaneity between times at clocks at different events. Any physical system that can be used to measure time (a conventional clock, a human body, etc.) follows the same rules.

Philosophy of Physics: Space and Time by Tim Maudlin goes over this very clearly, from a geometric perspective.

*General relativity doesn't change this essential point, it just says that the spacetime metric can vary from place to place, whereas in SR it is always the same.

  • @Conifold. I appreciate the all comments here. Lots of questions and some thoughts. At the moment most curious about your comment: “But it is unclear why someone needs an "individual clock" to "create new future paths", universal clock would do just as well.” That seems to be at variance with a deterministic world view held by many physicists. How would new paths arise in a world where the past fully determines the future and the present moment, should we locate it, is of no particular significance.
    – Don Foster
    Nov 16, 2021 at 19:55
  • You say "There is no defined meaning to the idea of an absolute simultaneity between times at clocks at different events." However, clocks can compensate to create simultaneity, as with satellites being in sync. Also, in the absolute sense, how is the 'now' on the satellite different from the 'now' on Earth? How is there no meaning to that? It seems quite straightforward. Nov 16, 2021 at 23:38
  • Perhaps, the complication with syncing over more convoluted space-time is that multiple, different light-paths and therefore timelines may connect two points. I contend that it is still 'now' everywhere though. Nov 17, 2021 at 7:07
  • @ Chris Degnen, the point is that whether or not 2 different events appear simultaneous will vary according to the reference frame, so they may or may not be simultaneous, there is no coordinate-invariant answer to the question. Nov 22, 2021 at 10:06
  • Re convoluted space-time - there is one and only one trajectory that light can follow between two points, but what this trajectory is will indeed be different depending on spacetime curvature, which results from the distribution of mass/energy. Nov 22, 2021 at 10:13

The strength of the ‘one clock’ argument is that you could build an atomic clock anywhere in the universe and it would appear to an observer that shares its frame of reference to run at the same speed. (same frame of reference = not moving at relativistic speed with respect to it) So while clocks moving at different speeds will tick at different rates, the rules that predict this are, as far as we know, consistent across the universe.

  • So a travelling spaceman moving in a known relative trajectory could calculate and know the time on this atomic clock even though his own clock would tick at a different rate. May 8, 2022 at 21:55
  • @Chris Degnen exactly, that’s how GPS satellites etc keep time even though the relativistic effects are large enough to be significant.
    – Frog
    May 9, 2022 at 2:00

From a street level view, the answer is no, the universe does not have one clock on the wall. Rather, it can be more usefully considered as a multiplicity of ‘clocks all the way down.’ In this view, being is a dynamical phenomenon and all composite, enduring physical objects are dynamical systems with innate tempos. One might analogize, say that in concert, physical objects create spacetime topology, puffing it up like a bag of microwave popcorn, or perhaps see time as a coral reef accretion of many differently gaited species.

Cadence in nature varies by more than 32 orders of magnitude as measured in the seconds units of the Système International metric system. Within this system we can measure time five orders of magnitude more accurately than any other base unit. There is a clock ‘on the wall’ at the Boulder, Colorado NIST laboratories that is accurate to about one second in the age of the universe. Every day they receive twenty billion inquiries asking, “What time is it?” As far as I know, all these inquiries to the NIST laboratories arise earth proximate and not from the universe at large. And, one may ask whether they are measuring time or making it.

For all its utility, SI time is part of an abstracted domain, an overlay on the topology of nature much like a cartographer’s latitude and longitude. Devices of measurement divide, perform a kind of Midas touch transformation that abstracts from running nature some fixed figure to fit within the crystalline matrix of our equations. But the map is not the territory. We cannot expect that a time defined in Boulder, Colorado is property of the universe as a whole.

  • But we’ve never had anything but a map, and yet we have knowledge of part of a single mind-independent world. Thus mapness may not be a mistake. Seems like a fair reply
    – J Kusin
    May 8, 2022 at 17:38
  • Existence (n.) late 14c., "reality," "existent," "exist, be;" from ex "forth" (see ex-) + sistere "cause to stand," from PIE *si-st-, reduplicated form of root *sta- "to stand, make or be firm." etymonline.com/word/existence#etymonline_v_14062 There exist in the universe asynchronous systems that do not depend on strict arrival times of external signals or messages for reliable operation, they have no global clock. en.wikipedia.org/wiki/Asynchronous_system Such systems have internal dynamics compounded of isochronous subsystems.
    – Don Foster
    May 9, 2022 at 14:09
  • > J Kusin True, our cognitive maps are as essential as our skin. Still, the map is not the territory. “The prudent mariner will not rely solely on any single aid to navigation.” – coastal chart legend, U.S. Coast Guard.
    – Don Foster
    May 9, 2022 at 14:31

I'd say we can apply Liebniz principle of indiscernability. Every electron is alike and so their innate sense of time is alike. So we get what looks like a universal clock. But in fact, it is a universal harmony.


The time experienced by satellites can be computationally adjusted to keep them functional for GPS, etc. They do not wander off into their own incalculable time when unobserved. There is no reason that the same cannot be said for more convoluted space-time. Consequently the one-clock idea pertains. In other words, the 'now' moment is universal.

To reiterate: Notionally, relativistic time difference are calculatable and can be synced to any unprivileged clock. For example, on the satellite add one second per hour and the satellite clock tells the same time as on Earth: Therefore one clock.

Edit 23/11/21

The counter-argument is that closed time-like curves (CTC) produced by a spinning black hole could scatter the 'now' moment over time, resulting in past and future at the same time.

  • I think that's only true because the satellite started off on earth. You were able to sync its clock at that point and then account for its acceleration to a new inertial frame.
    – Ewan
    Nov 17, 2021 at 19:39
  • @Ewan If the compensation calculation can be made - and it is the difficulty of this calculation that seems to be at issue - then the clocks could at least be adjusted to turn synchronously. And then any signal could be synchronised to. Even if, through gravitational lensing, you could see two images of the satellite (at different ages) the calculations would resolve to the same singular space-time at the target. Nov 23, 2021 at 12:49
  • its not the difficulty of the calculation, but the question of which observer is correct about the time.
    – Ewan
    Nov 23, 2021 at 13:50
  • @Ewan The actual time is arbitrary: Earth time, moon time. The point is that people on a satellite, on the moon and on Earth can use compensated clocks to coordinate in time, ("one clock"). And the same would apply over longer ranges, although the calculations become more difficult. Only if a closed timelike curve is involved does the calculation break down. Nov 23, 2021 at 14:03
  • how do you justify "the universe has one clock" when two observers at time t, disagree about what their clocks read and how fast time runs?
    – Ewan
    Nov 23, 2021 at 14:09

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