# What is the Clock?

- id: cmtukah3g00001op9k0buldcd
- url: https://wordplaytalk.com/p/cmtukah3g00001op9k0buldcd/what-is-the-clock
- kind: note
- author: Javier Nieto (@javi) — University of Illinois Urbana-Champaign
- posted: 2026-09-09T20:39:24.172Z (edited 2026-09-10T15:36:19.238Z)
- score: 2 · replies: 5
- format: markdown
- tags: clocks, distributed-algorithms, time
- series: part 1 of 1 in “Clocks” (id cmtmyp4ic00001dpk1dqdzble, https://wordplaytalk.com/series/cmtmyp4ic00001dpk1dqdzble/clocks)

## Post

Everyone knows what time it is.
Most coordination in our everyday lives relies on it.
Whether in our deadlines, schedules, or even cooking timers, we can take for granted that we share a common sense of time.

In this [series](https://social.javinieto.com/series/cmtmyp4ic00001dpk1dqdzble/clocks), I want to investigate how we've come to agree on time and connect it to my summer research with [Category Labs](https://www.category.xyz/).

Wikipedia defines the [clock](https://en.wikipedia.org/wiki/Clock) as "a device that measures and displays [time](https://en.wikipedia.org/wiki/Time)."
As we will see, time itself is defined by clocks, so this definition is rather circular.
So we will go the other way and start with the clock.

We will find more use in the physics definition of a clock (from [The Feynman Lectures on Physics, Volume I, Chapter 5-2](https://www.feynmanlectures.caltech.edu/I_05.html#Ch5-S2)):
> What really matters anyway is not how we _define_ time, but how we measure it. One way of measuring time is to utilize something which happens over and over again in a regular fashion—something which is _periodic_.

Let's start with the day as something periodic.
Count the days from one noon to the next.
We then have the clock as a sequence of _ticks_ (the passing of days), and a count of them.

$$C = (t_0, t_1, t_2, ...)$$

Note that the clock produces only the count and not _regularity_ in the increments.
The clock makes no claim that the duration between $t_0$ and $t_1$ equals the duration between $t_1$ and $t_2$.

**This is not a shortcoming of the formulation.
This is the situation.**
The clock on its own cannot establish that its ticks are at regular intervals, because there is nothing to be regular against.
The Feynman lecture gives an example of a man flipping an hourglass as soon as the last grain of sand goes from the top to the bottom.
He can then count how many flips occur in each day.
However, how can he rule out that the hourglass is slow at night and fast during the day?
Another passage from the [lecture](https://www.feynmanlectures.caltech.edu/I_05.html#Ch5-S2):
> All we can say is that we find that a regularity of one kind fits together with a regularity of another kind.

**Regularity is not a property of a clock.
It is the relation between two.**
Take $C': \mathbb{N} \to \mathbb{N}$ to be the function of hourglass flips with respect to the days, where the flip count starts with the day count, i.e., $C'(0) = 0$.
Plotting the hourglass flips against the days gives:
```tikz Figure 1: hourglass flips against days
\begin{tikzpicture}[x=1cm,y=0.0417cm,>=stealth]
  \draw[gray!45,very thin,xstep=1,ystep=24] (0,0) grid (7.4,192);
  \draw[->,thick] (0,0) -- (8,0) node[right] {$d$};
  \draw[->,thick] (0,0) -- (0,208) node[above] {$h$};
  \foreach \i in {1,...,7}{
    \draw[thick] (\i,0) -- (\i,-7);
    \node[below] at (\i,-7) {\footnotesize$\i$};
  }
  \foreach \j in {24,48,72,96,120,144,168,192}{
    \draw[thick] (0,\j) -- (-0.12,\j);
    \node[left] at (-0.12,\j) {\footnotesize$\j$};
  }
  \draw[very thick] (0,0) -- (7,168);
  \draw[very thick,dashed] (0,0) -- (7,189);
  \draw[<->,very thick] (7,168) -- (7,189);
  \draw[thick,densely dotted,red!75,opacity=0.8]
    (0,0) .. controls (1.5,70) and (4,130) .. (7,150);
\end{tikzpicture}
```
Linearity indicates _regularity_ between the two, where for every $d$ days we have $h$ hourglass flips.
The dotted curve represents an irregular hourglass that varies greatly in its number of daily flips.
The solid line represents our common notion of the day, where for every day, there are $24$ flips of the hourglass.
The dashed line represents another possibility for an hourglass $C''$: for every day, there are $27$ flips.

In this scenario, we cannot distinguish whether $C'$ is slow or $C''$ is fast. 
We must agree on which one to treat as correct, and calibrate the other to it.
This is how time becomes _standardized_.
Nothing in the comparison forces the choice.
Further, we could fix the day and say it is $24$ flips, or fix the hourglass and let the day be the one that varies.
Both are consistent with everything we have observed.

The next post will briefly go through the history of standardizing the _second_.

## Beside the post

- Context, 5,646 words: https://wordplaytalk.com/p/cmtukah3g00001op9k0buldcd/context
- Time: https://wordplaytalk.com/s/cmtukah4i00041op9z7n8k6z2
- Clock: https://wordplaytalk.com/s/cmtukce6300071op9xgfioewt

## Replies (5)

- **Anton Paramonov** (@anton144) · score 1 · 2026-09-14T20:39:41.227Z · id: cmu1pi3l7001n1ooc13o7vasq
  > This reminds me of an idea I first encountered in a Category Theory [lecture course]([https://](https://www.youtube.com/watch?v=I8LbkfSSR58&list=PLbgaMIhjbmEnaH_LTkxLI7FMa2HsnawM_)) by Bartosz Milewski. He said that some thing can be defined in two fundamental ways: either through all its properties or through all possible interactions with other things. Quite an insight!

- **Henry D’Angelo** (@henry) · score 0 · 2026-09-09T20:52:07.217Z · id: cmtukqtv400131op9gl3ekqve
  > Goodness me, a banger. I'll hopefully come back to this as I integrate into my thinking, but here is the high level point I connect on-- oftentimes, "ground truth" is actually the stacking of relations on top of each other. There is a bit of a "Kantian turn" one must do in thinking -- instead of trying to capture the thing-in-itself, one has to find the right phenomena to, in some way, restrict or lasso the thing-in-itself.

  - **Henry D’Angelo** (@henry) · score 1 · 2026-09-09T20:55:41.579Z · id: cmtukvf9n00071oo6113kfjht
    > It's remarkable how similar the question of how to create a clock is, to the question of how to do science at all! The question is, what phenomena can we bundle together to form some invariant?

    - **Javier Nieto** (@javi) · score 0 · 2026-09-09T20:59:51.676Z · id: cmtul0s8s000j1oo62mhi9bw4
      > Beautiful beautiful point. I'll see how I can incorporate this in the next post.

- **Anton Paramonov** (@anton144) · score 0 · 2026-09-14T20:42:33.654Z · id: cmu1plsmu00221ooct1ced5zo
  > It also makes me wonder about a biological aspect. How is time "implemented" in humans? How is a drummer possible?