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PNAS Cover: Earth BioGenome Project


fun + amusement

The Ptolemaic Clock — A Proposal

the standard clock

Consider the lowly wall clock. It's practical and generally tells the correct time. It's the same clock everywhere and after a while it gets boring pretty quickly—maybe now?

Non-standard clock with rotating bezel. / Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
In a standard clock, the bezel is fixed and the hands rotate.

In the regular clock the face bezels stay in place and the hands move. Why am I telling you this? Well, maybe you see where I'm going.

the Ptolemaic Clock

Who says it's the hands that have to rotate? Instead of rotating hands and a stationary bezel, consider the clock with stationary hands rotating bezels.

Non-standard clock with rotating bezel. / Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
In the Ptolemaic clock, the hands stay in place while independent minute and hour hand bezels rotate to simulate the movement of the hands.

In the Ptolemaic clock there are two independent bezels and two independent hands. The bezels rotate counterclockwise to simulate the standard clockwise motion of the hands. The hands are not moving but in the frame of reference of the bezels, it's the hands that are rotating. The position of the bezel is always related to the current time and the position of its corresponding hand.

The bezel can move clockwise.

Thanks to Rodrigo Goya for suggesting the name for this kind of clock—Ptolemaic Clock, named so after the geocentric Ptolemaic model of the solar system.

telling time on the Ptolemaic clock

To tell the time on the Ptolemaic clock is a process identical to using the standard clock. You look at the bezel numbers at the ends of the hour and minute hands.

On the fixed bezel layout, most people will take a short cut and tell the time by the position of the hands. This works as long as you have a standard clock. On a Ptolemaic clock the position of the hands tells you nothing.

Here is a Ptolemaic clock telling us it is 6:30. It uses the same position of hands as in the figures above.

You know this because the blue hour hand points to midway between 6 and 7 on the inner hour bezel and the grey minute hand points to 30 on the outer minute bezel.

Non-standard clock with rotating bezel. / Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
It is 6:30 on this Ptolemaic clock.

After 15 minutes, it's 6:45 and our Ptolemaic clock bezels have moved a little bit.

Non-standard clock with rotating bezel. / Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
It is 6:45 on this Ptolemaic clock.

Can you tell what time it is on the Ptolemaic clock below?

Non-standard clock with rotating bezel. / Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
If you answered 8:50, you are correct. It is 8:50.

customizing the Ptolemaic clock

Customizing your Ptolemaic clock is easy. Simply adjust the hands to desired positions and set the time by moving the bezels. The clock below shows the same time as the clock in the above figure — both show 8:50.

Non-standard clock with rotating bezel. / Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
This clock tells us it's 8:50. Compare this to the clock in the figure above, which also tells the same time.

ptolemaic clock — hard layout

In the clock design shown here, the hands are the same size and only differ by color. To make things less confusing, emphasize the hour hand.

To make things more confusing, remove all color and number cues, keeping only a single symbol on each of the bezels to indicate 12 o'clock and 0 minutes. This is shown in the clock below.

Non-standard clock with rotating bezel. / Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
In the hard layout of a Ptolemaic clock, there are fewer cues. I think it's 8:50.

news room parodies

Spice it up with multiple Ptolemaic clocks side-by-side telling the same time with different hand positions.

Suppose it is 2:30 in Vancouver—this is my location. The clocks below all show 2:30, but with hands set to 5:30, 11:30 and 7:30.

Non-standard clock with rotating bezel. / Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
Looks like a wall of clocks in a newsroom. Except these Ptolemaic clocks tell us that it's 2:30, three times over in Vancouver.

These hand positions are those that would appear on a standard clock showing the times in New York (5:30), Paris (11:30) and Tokyo (7:30).

Let's now use the Ptolemaic clock to show times at these three locations but with the hand set to the curiously satisfying layout of 10ish minutes to 2.

Non-standard clock with rotating bezel. / Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
A challenging panel of Ptolemaic clocks.

TIP

Set both hand positions to 12 o'clock and then remove the hands; to tell time, read the numbers on the hour and minute bezels at the apex of the clock.

EXTENSION

Sophisticated implementations of the Ptolemaic clock could periodically randomize hand positions to keep things interesting; by the time you've figured out the time in the morning, you're wide awake.

Every minute the clock randomly resets its hand positions. The movement is smooth and the bezels follow.

hardware implementation

If you would like to implement the Ptolemaic clock, I would be happy to hear from you. One should be able to take a regular wall clock, reverse the direction of the hand mechanism and rig a freely moving bezel to each of the minute and hour mechanism. The hands should not move and can be fixed to the front glass plate, for example.

conclusions

It should now be clear that the Ptolemaic clock is superior to the standard clock. The reasons are

  • it's much harder to tell time on the Ptolemaic clock, which makes your brain do more work
  • it tips its hat off to a simpler time when we didn't know anything and hints at the possibility of regression anytime
    • it will confuse everyone
    • you have a great excuse for being late
    • return to geocentric values!
  • you can customize your own Ptolemaic clock by moving the hands to arbitrary locations
    • two Ptolemaic clocks can have their hands and bezels at different positions but still be telling the same time
    • two Ptolemaic clocks can have their hands at the same position but be telling different times

VIEW ALL

news + thoughts

Cancer Cell cover

Sat 23-04-2022

My cover design on the 11 April 2022 Cancer Cell issue depicts depicts cellular heterogeneity as a kaleidoscope generated from immunofluorescence staining of the glial and neuronal markers MBP and NeuN (respectively) in a GBM patient-derived explant.

LeBlanc VG et al. Single-cell landscapes of primary glioblastomas and matched explants and cell lines show variable retention of inter- and intratumor heterogeneity (2022) Cancer Cell 40:379–392.E9.

Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
My Cancer Cell kaleidoscope cover (volume 40, issue 4, 11 April 2022). (more)

Browse my gallery of cover designs.

Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
A catalogue of my journal and magazine cover designs. (more)

Nature Biotechnology cover

Sat 23-04-2022

My cover design on the 4 April 2022 Nature Biotechnology issue is an impression of a phylogenetic tree of over 200 million sequences.

Konno N et al. Deep distributed computing to reconstruct extremely large lineage trees (2022) Nature Biotechnology 40:566–575.

Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
My Nature Biotechnology phylogenetic tree cover (volume 40, issue 4, 4 April 2022). (more)

Browse my gallery of cover designs.

Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
A catalogue of my journal and magazine cover designs. (more)

Nature cover — Gene Genie

Sat 23-04-2022

My cover design on the 17 March 2022 Nature issue depicts the evolutionary properties of sequences at the extremes of the evolvability spectrum.

Vaishnav ED et al. The evolution, evolvability and engineering of gene regulatory DNA (2022) Nature 603:455–463.

Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
My Nature squiggles cover (volume 603, issue 7901, 17 March 2022). (more)

Browse my gallery of cover designs.

Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
A catalogue of my journal and magazine cover designs. (more)

Happy 2022 `\pi` Day—
three one four: a number of notes

Mon 14-03-2022

Celebrate `\pi` Day (March 14th) and finally hear what you've been missing.

“three one four: a number of notes” is a musical exploration of how we think about mathematics and how we feel about mathematics. It tells stories from the very beginning (314…) to the very (known) end of π (...264) as well as math (Wallis Product) and math jokes (Feynman Point), repetition (nn) and zeroes (null).

Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
Listen to `\pi` in the style of 20th century classical music. (details)

The album is scored for solo piano in the style of 20th century classical music – each piece has a distinct personality, drawn from styles of Boulez, Feldman, Glass, Ligeti, Monk, and Satie.

Each piece is accompanied by a piku (or πku), a poem whose syllable count is determined by a specific sequence of digits from π.

Check out art from previous years: 2013 `\pi` Day and 2014 `\pi` Day, 2015 `\pi` Day, 2016 `\pi` Day, 2017 `\pi` Day, 2018 `\pi` Day, 2019 `\pi` Day, 2020 `\pi` Day and 2021 `\pi` Day.

PNAS Cover — Earth BioGenome Project

Fri 28-01-2022

My design appears on the 25 January 2022 PNAS issue.

Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
My PNAS cover design captures the vision of the Earth BioGenome Project — to sequence everything. (more)

The cover shows a view of Earth that captures the vision of the Earth BioGenome Project — understanding and conserving genetic diversity on a global scale. Continents from the Authagraph projection, which preserves areas and shapes, are represented as a double helix of 32,111 bases. Short sequences of 806 unique species, sequenced as part of EBP-affiliated projects, are mapped onto the double helix of the continent (or ocean) where the species is commonly found. The length of the sequence is the same for each species on a continent (or ocean) and the sequences are separated by short gaps. Individual bases of the sequence are colored by dots. Species appear along the path in alphabetical order (by Latin name) and the first base of the first species is identified by a small black triangle.

Lewin HA et al. The Earth BioGenome Project 2020: Starting the clock. (2022) PNAS 119(4) e2115635118.



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aikido | analogies | animals | astronomy | comfortable silence | cosmology | dorothy parker | drumming | espresso | fundamental forces | good kerning | graphic design | humanism | humour | jean michel jarre | kayaking | latin | little fluffy clouds | lord of the rings | mathematics | negative space | nuance | perceptual color palettes | philosophy of science | photography | physical constants | physics | poetry | pon farr | reason | rhythm | richard feynman | science | secularism | swing | symmetry and its breaking | technology | things that make me go hmmm | typography | unix | victoria arduino | wine | words