Martin Krzywinski / Genome Sciences Center / mkweb.bcgsc.ca Martin Krzywinski / Genome Sciences Center / mkweb.bcgsc.ca - contact me Martin Krzywinski / Genome Sciences Center / mkweb.bcgsc.ca on Twitter Martin Krzywinski / Genome Sciences Center / mkweb.bcgsc.ca - Lumondo Photography Martin Krzywinski / Genome Sciences Center / mkweb.bcgsc.ca - Pi Art Martin Krzywinski / Genome Sciences Center / mkweb.bcgsc.ca - Hilbertonians - Creatures on the Hilbert Curve
Without an after or a when.Papercut feat. Maiken Sundbycan you hear the rain?more quotes

c: 3


In Silico Flurries: Computing a world of snow. Scientific American. 23 December 2017


data visualization + art

If you like space, you'll love my 2017 Pi Day art which imagines the digits as a star catalogue. Meet the Quagga and Aurochs—the Constellations in this sky are extinct animals and plants.

null
from an undefined
place,
undefined
create (a place)
an account
of us
— Viorica Hrincu

Sometimes when you stare at the void, the void sends you a poem.

Universe—Superclusters and Voids

Universe - Superclusters and Voids / Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
The Universe — Superclustesr and Voids. The two supergalactic hemispheres showing Abell clusters (blue), superclusters (magenta) and voids (black) within a distance of 6,000 million light-years from the Milky Way.

The average density of the universe is about `10 \times 10^{-30} \text{ g/cm}^3` or about 6 protons per cubic meter. This should put some perspective in what we mean when we speak about voids as "underdense regions".

listen: there's a hell
of a good universe next door; let's go
—e.e. cummings (pity this monster, manunkind)

evolution of the universe superclusters and voids poster

Below I describe the design process of the poster, which is available in various color schemes.

The distances on the poster are all light-travel distances. To learn more about how distances are measured in the Universe, I've put together a short tutorial and calculator on space expansion, light-travel and comoving distances.

The reference section links to reading material about the details of individual elements, such as the coordinate system.

inspiration

I was motivated by this map by Richard Powell of the Universe within 2 billion light years.

Universe - Superclusters and Voids / Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
This is a map of all the major known superclusters within two billion light years plotted onto the supergalactic plane. Each point on this map is a rich cluster of galaxies containing hundreds of galaxies as listed in Abell's catalog of rich clusters of galaxies. This map does not show every rich cluster but only those which are grouped together into large supercluster formations. Each of these superclusters must also contain hundreds or maybe thousands of smaller groups of galaxies. This map is clearly not complete, the plane of our galaxy runs approximately down the centre of the map and most astronomers prefer to study galaxies that are far away from this plane where there is a lot less gas and dust obscuring our view of the universe. This explains why most of the known superclusters are on the left and right sides of the map (original caption by Richard Powell).

I started dutifully tracing the map and I got as far as the image below...

Universe - Superclusters and Voids / Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
Beginning tracing the map by Richard. (zoom)

...before I decided that I should just parse Richard's list of superclusters and programmatically generate the map.

#Common Name   Equatorial   Supergal Redsh Dis  Size Con     Abell clusters in the
#              Coordinates  Coords   z     Mly  Mly          in the supercluster
#              RA    Dec    L°  B°
Centaurus      13 00 -32.0  148  -7  0.014 194  150  Cen-Hya 1060,3526,3565,3574,3581
Perseus-Pisces 02 32 +39.8  341  -8  0.016 222  100  Per-And 262,347,426
Pavo-Indus     20 34 -37.0  230 +32  0.017 235  100  Ind-Mic 3656,3698,3742
...

You can download a plain-text and tidied version of this file, in which the Abell list for a supercluster is now on a single line.

Below is my first attempt. This is a top-down view of the supergalactic equator. Clusters in the Southern Supergalactic Hemisphere are joined to the equator plane by dotted lines.

Universe - Superclusters and Voids / Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
Superclusters projected top-down on the supergalactic equator. (zoom)

I liked the angled view of Richard's map, so I adjusted the code to achieve this.

Universe - Superclusters and Voids / Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
Superclusters projected projected on the supergalactic equator. View angle is about 15 degrees. (zoom)

I knew I wanted to draw the voids on the map, so I scraped some coordinates from Wikipedia's List of Voids and added them to the map.

Universe - Superclusters and Voids / Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
Superclusters and voids projected on the supergalactic equator. View angle is about 15 degrees. (zoom)

The object on the far left is the Eridanus Void, which is a hypothesized void to explain the CMBR Cold Spot. I wanted this in the map, but the scale made it difficult—Richard's list of clusters only went out as far as about 2.7 billion light-years but The Eridanus Void is between 6 and 10 billion light years away.

To accomodate this void on the map I needed either (a) more superclusters to fill out the map and/or (b) scale the distance with a log (e.g. `log(d)`) or power transformation (e.g. `d^k`).

There was also another issue: my code implemented an erzats 2-dimensional projection, not an actual orthographic or perspective 2d projection.

VizieR astronomical catalogues

For more data, I went to the VizieR database of astronomical catalogues. It's a little clunky but offers a portal to an absolutely immense amount of data. Once you gain familiarity with the interface, it can feel like the Universe is within reach.

I made use of the Abell catalogue and the supercluster catalogue that groups the Abell clusters into superclusters.

VII/110A Rich Clusters of Galaxies, Abell+, 1989

J/MNRAS/445/4073 Two catalogues of superclusters, Chow-Martinez+, 2014

applying an orthographic projection

When these catalogues are plotted using an authentic projection, the result is the map below.

Universe - Superclusters and Voids / Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
Superclusters (orange), Abell clusters (blue) and voids (black) from the VizieR catalogues VII/110 and J/MNRAS/445/4073 projected on the supergalactic equator. View angle is 15 degrees. (zoom)

building the poster

When both hemispheres are shown together, there's a lot of overlap between objects close to the equator. To mitigate this, below is my first attempt at separating the hemispheres and building a poster of the map.

Universe - Superclusters and Voids / Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
First draft of a poster of superclusters, Abell clusters and voids. (zoom)

Below is a close crop of a region of the poster. At this point, I'm still using the bitmap Mini 7 Condensed font and including labels for all Abell and superclusters.

Universe - Superclusters and Voids / Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
Close up of a region of the early draft of the poster. (zoom)

Each supercluster also has its constellation designation. This tiny detail took a while to work out. The coordinates had to be precessed to 1875 to apply the IAU constellation boundary criteria.

VI/42 Identification of a Constellation From Position, Roman, 1987

adding stars and constellations

To manage the density of the labels—especially the constellation labels—I thought it would be better to simply show the constellations. I thought that the natural place to put the constellations would be the surface of the supergalactic sphere at a sufficient distance from the origin to accommodate all the objects within the sphere.

I threw in the sky's brightest 9,110 stars from the Yale Catalogue of Bright Stars.

V/50 Bright Star Catalogue, 5th Revised Ed., Hoffleit+, 1991

I obtained the list of constellation shapes from Marc van der Sluys' list. For each constellation, this list gives the pairs of stars in the Yale Catalogue of Bright Stars that are connected by the constellation lines.

BSC (Yale Catalogue of Bright Stars) constellation edges. by Marc van der Sluys

However, many of Marc's constellations shapes were not the asterisms sanctioned by the IAU. I therefore corrected all the constellation shapes by manually examining the IAU map and cross-referencing the stars to the Yale Catalogue of Bright Stars. Ugh.

My list of IAU constellation shapes conveniently includes the J2000 right ascension and declination for each stars in the pair, along with their HR index, magnitude and name.

IAU Constellation shapes as edges between BSC stars (Yale Catalogue of Bright Stars) by Martin Krzywinski

For example, Cassiopeia's familiar "W" appears as 4 lines that indicate the connections between HR stars 21-168-264-403-542.

Cas  21  2.294583 59.149722 2.27 bet Caph|bet Cas|11 Cas	        
    168 10.127083 56.537222 2.23 alf Schedar|alf Cas|18 Cas
Cas 168 10.127083 56.537222 2.23 alf Schedar|alf Cas|18 Cas	
    264 14.177083 60.716667 2.47 gam BU 499A|BU 1028|gam Cas|27 Cas
Cas 264 14.177083 60.716667 2.47 gam BU 499A|BU 1028|gam Cas|27 Cas
    403 21.454167 60.235278 2.68 del Ruchbah|BUP 19A|del Cas|37 Cas
Cas 403 21.454167 60.235278 2.68 del Ruchbah|BUP 19A|del Cas|37 Cas
    542 28.598750 63.670000 3.38 eps Segin|eps Cas|45 Cas

For more details about the constellations see my IAU Constellation Shape Resources.

colors, fonts and design choices

At this point, I went with a vibrant magenta background and switch to the Gotham typeface for the text. I also separeated the hemispheres completely, which makes the map look a little like the hemispheres of the brain. And that's ok.

Universe - Superclusters and Voids / Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
The constellations and stars from the Yale Catalogue of Bright Stars projected on the supergalactic sphere. (zoom)

Once I dropped the Abell clusters, superclusters and voids into the sphere, it was beginning to look crowded.

Universe - Superclusters and Voids / Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
Clusters, superclusters and voids in the North Supergalactic Hemisphere, together with constellations and stars. (zoom)

From the close crop below, you can see that the drop lines for each object are clusttering the space.

Universe - Superclusters and Voids / Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
Close crop of clusters, superclusters and voids in the North Supergalactic Hemisphere, together with constellations and stars. (zoom)

I struggled with these drop lines. On one hand, I thought they were very important because they anchored the objects to the equator and thus provided a better sense of the object's position. On the other hand, they added to the busyness of the map. Ultimately I settled on a compromise. An object's drop line would only be drawn if it didn't have a neighbouring object of the same type.

a poetic collaboration

I'm very eager to find ways to combine my work with poetry.

This poster features a poem by Viorica Hrincu. It's about nothingness and the somethingness that can arise from it, if we find it. It appears on the bottom right of the poster. Tucked, but not away.

null
from an undefined
place,
undefined
create (a place)
an account
of us
— Viorica Hrincu

Previously, I've collaborated with Paolo Marcazzan for my 2017 `\pi` Day `\pi` in the Skya> poster. There, Paolo contributed "Of Black Body", a poem about thermodynamics, constellations and the truth we might find there. For Paolo, the poem hints at our plight (and flight): "For the earthbound, the questions and concerns remain those of identity, passage, escape from transiency, and slow tempering of hope."

interpretive panels and stories

It's likely that neither the coordinate system nor the elements in this map are familiar to most people. Supergalactic what? And what do you mean comoving isn't the first step in cohabitation?

To make the poster accessible, I started adding panels around the map that explained what is drawn, how to read the map, the coordinate system, what superclusters and voids are. I also threw in a few mythological stories, such as the one about Orion and his dogs and about Eridanus.

Also explained are the difference between light-travel and comoving distance along with small graphs that illustrate these concepts.

Read all the stories on the poster.

Universe - Superclusters and Voids / Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
Adding stories and interpretive panels to the poster— close to a final version. (zoom)
VIEW ALL

news + thoughts

Molecular Case Studies Cover

Fri 06-07-2018

The theme of the April issue of Molecular Case Studies is precision oncogenomics. We have three papers in the issue based on work done in our Personalized Oncogenomics Program (POG).

The covers of Molecular Case Studies typically show microscopy images, with some shown in a more abstract fashion. There's also the occasional Circos plot.

I've previously taken a more fine-art approach to cover design, such for those of Nature, Genome Research and Trends in Genetics. I've used microscopy images to create a cover for PNAS—the one that made biology look like astrophysics—and thought that this is kind of material I'd start with for the MCS cover.

Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
Cover design for Apr 2018 issue of Molecular Case Studies. (details)

Happy 2018 `\tau` Day—Art for everyone

Wed 27-06-2018
Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
You know what day it is. (details)

Universe Superclusters and Voids

Mon 25-06-2018

A map of the nearby superclusters and voids in the Unvierse.

By "nearby" I mean within 6,000 million light-years.

Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
The Universe — Superclustesr and Voids. The two supergalactic hemispheres showing Abell clusters, superclusters and voids within a distance of 6,000 million light-years from the Milky Way. (details)

Datavis for your feet—the 178.75 lb socks

Sat 23-06-2018

In the past, I've been tangentially involved in fashion design. I've also been more directly involved in fashion photography.

It was now time to design my first ... pair of socks.

Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
Some datavis for your feet: the 178.75 lb socks. (get some)

In collaboration with Flux Socks, the design features the colors and relative thicknesses of Rogue olympic weightlifting plates. The first four plates in the stack are the 55, 45, 35, and 25 competition plates. The top 4 plates are the 10, 5, 2.5 and 1.25 lb change plates.

The perceived weight of each sock is 178.75 lb and 357.5 lb for the pair.

The actual weight is much less.

Genes Behind Psychiatric Disorders

Sun 24-06-2018

Find patterns behind gene expression and disease.

Expression, correlation and network module membership of 11,000+ genes and 5 psychiatric disorders in about 6" x 7" on a single page.

Design tip: Stay calm.

Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
An analysis of dust reveals how the presence of men, women, dogs and cats affects the variety of bacteria in a household. Appears on Graphic Science page in December 2015 issue of Scientific American.

More of my American Scientific Graphic Science designs

Gandal M.J. et al. Shared Molecular Neuropathology Across Major Psychiatric Disorders Parallels Polygenic Overlap Science 359 693–697 (2018)

Curse(s) of dimensionality

Tue 05-06-2018
There is such a thing as too much of a good thing.

We discuss the many ways in which analysis can be confounded when data has a large number of dimensions (variables). Collectively, these are called the "curses of dimensionality".

Martin Krzywinski @MKrzywinski mkweb.bcgsc.ca
Nature Methods Points of Significance column: Curse(s) of dimensionality. (read)

Some of these are unintuitive, such as the fact that the volume of the hypersphere increases and then shrinks beyond about 7 dimensions, while the volume of the hypercube always increases. This means that high-dimensional space is "mostly corners" and the distance between points increases greatly with dimension. This has consequences on correlation and classification.

Altman, N. & Krzywinski, M. (2018) Points of significance: Curse(s) of dimensionality Nature Methods 15:399–400.