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Roope Kaaronen

@roopekaaronen.net
2K followers 571 following 2.6K posts

Forager of information and mushrooms • "String theorist" • Cognitive science, cultural evolution, cognitive anthropology, ethnomathematics • roopekaaronen.net • Kayaking, music, nature, photography

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Roope Kaaronen @roopekaaronen.net · 18h
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Roope Kaaronen @roopekaaronen.net · 29/09/2026
a pier / a disapier
A pier (in Helsinki by the calm Baltic sea, mostly in good shape with common eiders in the background)A disapier (a pier by the Baltic sea, but all the planks are missing)
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Roope Kaaronen @roopekaaronen.net · 27/09/2026
Did you know humans around the world have made string figures (cat's cradles)? And even stranger, the exact same figures to surprising degrees of complexity. In the thread below, we try to unravel this mystery:
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Roope Kaaronen @roopekaaronen.net · 25/09/2026
Aamun Hesarissa pohdin syntyjä syviä. www.hs.fi/tiede/art-20...
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Roope Kaaronen @roopekaaronen.net · 24/09/2026
Blackbirb.
Blackbird perching on a rhododendron.
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Roope Kaaronen @roopekaaronen.net · 23/09/2026
Also, an argument can be made that hating these beings should be illegal.
A little gosling in Helsinki. Looks almost like a fluffy bunny. Photo by me, perhaps 2022.
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Roope Kaaronen @roopekaaronen.net · 23/09/2026
The most hated birds of Finland are quite beautiful if you are open-minded. Art deco.
Two barnacle geese by the sea in Helsinki.Barnacle goose by the sea, Helsinki.
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Roope Kaaronen @roopekaaronen.net · 18/09/2026
This article wins the data visualisation of the month contest. www.mdpi.com/2571-550X/9/...
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Roope Kaaronen @roopekaaronen.net · 07/09/2026
I feel so blessed to see the Sandstorm steps every day as I go to work.
Helsinki cathedral AKA Sandstorm church
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Roope Kaaronen @roopekaaronen.net · 02/09/2026
When listening to old Finnish children's songs, the Youtube algorithm almost always escalates to full-steam socialism. Man, the 70s were wild. A million little ants, unite! 🚩
Album cover of A Million Little Ants by Karviaiset. Five ants with a red flag.
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Roope Kaaronen @roopekaaronen.net · 01/09/2026
Nimittäin aiemmin ihmeteltiin sitä, että ihmiset ympäri maailman ovat tehneet tismalleen samanlaisia narukuvioita. Muinaisia keksintöjä nämäkin.
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Roope Kaaronen @roopekaaronen.net · 01/09/2026
Juuri nyt työn alla: ihmiset ympäri maailman ovat piirtäneet tai rakentaneet käytännössä tismalleen samanlaisia labyrintteja. Mitähän ihmettä nyt taas.
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Roope Kaaronen @roopekaaronen.net · 31/08/2026
Really enjoyed this one. On "Tower of Babel" -like myths, Berezkin's mythology database claims to have dozens of such cases indexed. Not sure how carefully they have been vetted. :) Attached is one similar case I found when doing mushroom research.
Many thousands of years ago the inhabitants of the earth were all of one race and spoke but one language. Suddenly a fungus of enormous size made its appearance and continued to grow larger and higher every day and was looked upon by the people as a shelter from the sun and rain which had been sent them by the gods; but at last it grew to such a size that their crops, on which they depended entirely for food, suffered by being deprived of the blessings of the sun, rain, and dew, and they began to wish that they had stopped it's (sic) growth before. Sacrifices were offered to the gods who were prayed to remove the fungus from the face of the earth, but their prayers were without effect, and as time went on it became necessary for the preservation of life to cut it down whether the gods resented such action or not. So it was felled, cut up, and everybody eat [sic] of it with the result that they all fell into a kind of stupor and began to speak every man a different language, and the confusion was so great that they scattered over the face of the earth, and it was in this way that the many languages now spoken in the world originated.

—An Iban origin story from Borneo by Howell (1908, p. 78).
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Roope Kaaronen @roopekaaronen.net · 09/07/2026
inb4 "haha KKK" – when I was a kid, we actually had "KKK Supermarket".
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Roope Kaaronen @roopekaaronen.net · 09/07/2026
Compare to this truck in northern Finland.
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Roope Kaaronen @roopekaaronen.net · 09/07/2026
In a highly unexpected turn of events, Iranians are parading Ali Khamenei's frozen body in a *Finnish supermarket truck*.
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Roope Kaaronen @roopekaaronen.net · 29/06/2026
A job I'm most proud of is my tenure as the Shedmaster of a 93-year-old kayaking club. It's voluntary work, and I maintain a fleet of 50 kayaks. Fixing them and keeping them seaworthy, enabling a hobby for 200+ people. Kayaks have taken me to amazing places and I want others to experience it, too.
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Roope Kaaronen @roopekaaronen.net · 29/06/2026
Morning run with stroller, baby falls asleep, end run by jumping into the cold Baltic sea. Peak parental leave. The running stroller has easily been the best parent purchase so far. 100s of km already. Surprisingly easy to run with. And the baby enjoys these running naps.
The sea by coastal Helsinki. Thule running stroller in front.
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Roope Kaaronen @roopekaaronen.net · 18/05/2026
Got a new toy. I play many instruments, but not the keyboard. I was watching Billy Preston playing on the Get Back documentary and that was the final straw. Time to learn a new one.
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Roope Kaaronen @roopekaaronen.net · 13/05/2026
Tänään opin, että Pikku Prinssi on käännetty myös savoksi.
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Roope Kaaronen @roopekaaronen.net · 13/05/2026
Hetkonen. Eikös tämä hallitus liki ensitöikseen poistanut aikuiskoulutustuen? Miten tämä nyt eroaa siitä? Ei siinä, parempi näin kuin toisin. /Badabim
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Roope Kaaronen @roopekaaronen.net · 13/05/2026
On se vaan kiero tilanne, että tällainen kehitys tulkitaan Suomen taloudelle ja hyvinvoinnille elintärkeänä. Ja että ilman ei pärjätä. Ymmärrän kyllä, miten kuluttajaluottamuksen puute on ongelma. Oikeasti. Mutta pikamuoti +13%, lentäminen ja autoilu +11%... Kyllä tämä on tuhon tie.
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Roope Kaaronen @roopekaaronen.net · 26/04/2026
If a native English speaker has an issue with that... So be it? But I hope they some day take note of what a massive privilege it is to be able to do science in their native language. And notice how we cater to their privilege (which, of course, also has a problematic colonial history!).
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Roope Kaaronen @roopekaaronen.net · 31/03/2026
That's the last of the sea ice melting. I am so ready for spring. Everything looks HD and colourful.
Last sheet of sea ice melting on the Baltic sea in Helsinki. Sunny morning, blue sky and blue sea.
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Roope Kaaronen @roopekaaronen.net · 15/03/2026
A reviewer for the Illustrated Times (1867) described their show in London. The top, they wrote, "looks like a living thing [...] spinning up and down a long stick [...] then along the outstretched arms and across the back [...] upon the ridge of an open fan, and finally upon the edge of a sword."
Matsui Gensui at St Martin’s Hall, London. From Illustrated London News, February 23 1867. Picture of a Japanese man juggling a spinning top on a thin stick.
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Roope Kaaronen @roopekaaronen.net · 15/03/2026
Top of the morning! Today: the Matsui Gensui Troupe, a family of Japanese top-spinners who toured Europe in the 1860s. This 1865 woodblock print and photo show members of the Troupe performing tricks including spinning tops on fans, planks, edges of swords, and stacking them on top of each other.
A Japanese woodblock print from 1865 illustrating six members of the Matsui 
Gensui Troop of Top Spinners, a family of top-spinners famed for their skills. Depicted tricks include spinning 
a top upon a fan (top left) and a plank (top centre), a ‘fountain top’ shooting water (top centre), a rice lantern 
top (top right), whipping multiple tops simultaneously (bottom left), rolling a top on one’s shoulder (bottom 
centre), and spinning numerous tops on top of each other (bottom right). Public domain.March Matsui Gensui XVI (Sukegurō) toured Britain performing top spinning acts in Ipswich. Here he balances a top on the blade of a sword.
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Roope Kaaronen @roopekaaronen.net · 13/03/2026
I see yours and raise mine. Copper body with ruby contact point. Yes, it's a video.
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Roope Kaaronen @roopekaaronen.net · 13/03/2026
Top of the morning to you! This top is an interesting one. A whip-top with ivory inlays in alternating colours. It's from the Tomb of Tutankhamun! Over 3000 years old. "The top was one of the most beloved toys of Egyptian children." Source: www.globalegyptianmuseum.org/record.aspx?...
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Roope Kaaronen @roopekaaronen.net · 12/03/2026
Endnote: tops also feature in literary texts by Plato, Homer, Virgil, etc., the latter marvelling the liveliness of the top! Thanks to top-notch collaborators @felixthehauskat.bsky.social, @izzywisher.bsky.social, @ndersen.bsky.social, Marlena Billings, Charles Egeland & Rebecca Schwendler. / end
Then, woe-begone, by dark dreams goaded on,
she wanders aimless, fevered and unstrung
along the public ways; as oft one sees
beneath the twisted whips a leaping top
sped in long spirals through a palace-close
by lads at play: obedient to the thong,
it weaves wide circles in the gaping view
of its small masters, who admiring see
the whirling boxwood made a living thing
under their lash.
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Roope Kaaronen @roopekaaronen.net · 12/03/2026
We also argue that the top may be one of humanity’s early experiments in ethnophysics. Spinning a top lets you isolate/observe angular momentum and gyroscopic stability, rarely visible in nature. The toy might even pre-date the tool: spindle whorls, (fire) drills, wheel rely on similar principles.
A Karelian spindle whorl (kerdainvärttinä) made of wood. Looks a lot like a spinning top. But which was invented first, top or spindle? Image from Finna: https://finna.fi/Record/museovirasto.11423084571889470421B06DB341AA35A Saami drill. From: https://finna.fi/Record/siida.sda-26490
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Roope Kaaronen @roopekaaronen.net · 12/03/2026
Beyond play, tops feature in harvest rituals, wind-calling ceremonies, mourning rites, mythology, cosmology… We discuss a *lot* of such top-lore. Tops are also highly competitive. In some societies, top-spinning was the most popular game, with players trying to split their opponents' tops in half.
A Kayan boy aiming a peg-top, to be thrown at the top of his opponent, in Borneo ca. 1927. Games of this knock-your-opponent variety are especially common throughout Malayo-Polynesian societies. Public domain, original by Hendrik Freerk Tillema available at https://hdl.handle.net/20.500.11840/1358849.
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Roope Kaaronen @roopekaaronen.net · 12/03/2026
We also establish a baseline of top sizes and materials for archaeologists. Most tops are made of wood, seeds, fruits... materials that decompose. The archaeological record almost certainly underrepresents tops. Yet: there was nothing stopping Late Pleistocene hunter-gatherers from making them.
Dimensions of the four spinning top types in our dataset. Rug plots represent partial data (where only one of height/diam. is available).
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Roope Kaaronen @roopekaaronen.net · 12/03/2026
The peg-top is different. It clusters across South(east) Asia, esp. in Malayo-Polynesian societies. Unlike other tops, it’s tricky to figure out how to spin a peg-top just by looking at one. You need someone to show you. We think this opacity explains why it spread mostly by cultural transmission.
An Ot Danum peg-top made of wood with cord. More details at: https://hdl.handle.net/20.500.11840/195161
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Roope Kaaronen @roopekaaronen.net · 12/03/2026
Twirlers, whip-tops, and supported tops are found practically everywhere in our ethnographic/archaeological data. Their mechanical simplicity means they were likely invented independently many times over: stick a twig through an acorn and you have a twirler. I tried this myself last autumn:
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Roope Kaaronen @roopekaaronen.net · 12/03/2026
We asked: are different top types distributed randomly across the globe, or do some show spatial clustering suggestive of cultural transmission? We built a geographically explicit dataset and measured patterns of clustering.
Four maps each representing the geographical distribution of a spinning top type.
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Roope Kaaronen @roopekaaronen.net · 12/03/2026
Tops are ancient. The oldest known specimens are twirler tops from the tomb of Hemaka in Egypt, ca. 5100 years old (first post). They were valuable items, made of copper, crystal, ivory, etc., stored in an ornate box. We are also aware of tops in Ancient Middle-East, India, Greece, by the Inka, etc.
A man (left) and a youth (right) spinning a whip-top. The motif is traced from a Greek ceramic kylix vessel dated to 480–470 BCE. According to Johns Hopkins Archaeological Museum (Lamont, 2021), ‘the man wears a chlamys and the traveler’s cap that often characterize Hermes.’ The scene may thus represent the youth dedicating his childhood top to Hermes (see also Lambrugo et al., 2023). This refers to a rite of passage also described in the Greek Anthology (6.309): ‘To Hermes [he] hangs up these toys of his boyhood: his noiseless ball, this lively boxwood rattle, his knuckle-bones he had such a mania for, and his spinning-top.’ Image courtesy of the Johns Hopkins Archaeological Museum (accession no. B9). Reprinted and traced with permission.An Inka child playing with a whip-top, as documented in the Indigenous chronicle Primer nueva corónica y buen gobierno (Felipe Guamán Poma de Ayala, 1615, p. 208). The game is depicted in a context of colonial indoctrination of Indigenous children. However, the game was likely native to the Inka: Rowe (1946, p. 288) notes that the whip-top was called pisqoynyo in Quechua, and Bernabé Cobo writes in Historia del Nuevo mundo (ca. 1653) of an Indigenous spinning top game called piscoynu (Cobo, 1890, p. 228). This indigeneity is further corroborated in the earliest comprehensive Quechua–Spanish–Quechua dictionary (González Holguín, 1608, pp. 285, 323).Four children playing with what have been interpreted as spinning tops (Griffiths, 1896, p. 30). The picture is cropped from an early Buddhist mural painting from Ajanta Caves (Cave 2) in Western India, ca. 475–477 CE. The tops depicted (the two lollipop-shaped white figures on the ground, centre bottom) are likely peg-tops with long pegs (iron nails), a design still typical to South Asia. Image cropped from Plate 31 in Griffiths (1896), public domain.
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Roope Kaaronen @roopekaaronen.net · 12/03/2026
First, some basic top-ology. Tops come in four types, classified by the mechanism by which you set them spinning. A. Twirler: twisted by hand B. Supported top: launched with a cord and handle C. Peg-top: thrown with a wound string D. Whip-top: kept going by whipping its side
A.	Twirler. A twirler, also known as the finger top, is set spinning by manually twisting its stem. Typically, this is done between the index finger and thumb, but on a sufficiently long stem it may also be rubbed between the palms of both hands. To initiate motion, the user grips the stem firmly and imparts a rapid twisting motion, swiftly releasing the top to allow it to spin freely on its contact point. The most common form of twirler is one where a peg (typically wood) pierces a perforated disc, seed, or fruit. [Image: A Chukchi (Chukotka, Russia; 1890–1901) twirler top with radial ornaments, 14.5 cm high. Public domain (Bogoras, 1909, p. 272).]B.	Supported top. A supported top is otherwise like the twirler, and may in principle have an equivalent design, but its spin is initiated using a cord, making use of an auxiliary launching handle. The top is placed securely into the supporting launcher to hold it upright, and a cord is wound tightly around the top’s stem. The user firmly tugs on the string to impart rotation to the top, promptly removing the handle to release the top to spin on its own. Supported tops are commonly called ‘humming tops,’ since the string imparts such rapid motion that any perforation in the top’s body might produce a humming or buzzing sound. [Image: A Kerek (Chukotka, Russia; 1890–1901) supported top, made of ivory and adorned with geometric designs. The upper knob has four sides with a face on each side. Two faces represent spirits, and the other two represent men. Four persons would gather around the top and spin it; when the top ceased to spin, those faced by the spirits would lose. The serrated hole in the handle would produce a rattling sound. Public domain (Bogoras, 1909, pp. 272–274).]C.	Peg-top. A peg-top is typically shaped like a pear, egg, or cone, commonly carved or lathed from a single piece of wood. Unlike other tops, it is spun by throwing: one end of the cord is snugly wound around the top, and the other attached to the user’s finger or hand. The user casts the top diagonally toward the ground, sometimes accompanied by a sharp tug of the string, imparting rapid rotation to the top. Peg-tops commonly have a stem (peg) made from metal (e.g., an iron nail), providing a hard and low-friction tip to spin on. Peg-tops typically require more skill than other types of tops, and are frequently used in competitive play, including games where users aim to strike and knock down an opponent’s top. [Image: An assortment of peg-tops by South Torajan peoples (Sulawesi, Indonesia; 1920–1930), varying in shape, size, and cord-winding techniques. Public domain (Kruyt, 1932, p. 480).]D.	Whip-top. Typically conical or cylindrical in shape, whip-tops are initially spun either by hand or by winding and pulling a whip around them. The top’s spin is then sustained or accelerated by repeated slashing of the top’s side with a whip (usually a plant-based cord or leather thong(s) attached to a stick). The whipping maintains or increases the top’s rotational speed and can be used to direct the top’s movement across a surface. Precise repeated whipping motions can in principle maintain the top’s motion indefinitely. [Image: A set of whip-tops by the Crow (top row) and Oglala (bottom row incl. whip) (US; ca. 1900). Public domain (Culin, 1907, p. 745).]
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Roope Kaaronen @roopekaaronen.net · 12/03/2026
Play was historically quite neglected in anthropology and archaeology. So much so that one of the most widespread games in human history has never received a systematic cross-cultural study. To amend that, we systematically compiled a dataset of 1391 spinning tops from 347 societies.
The 347 cultures represented in our dataset. Tops are found all over the globe. The shapes of pins vary by traditional subsistence economy (based on HRAF data, where available). Coordinates are sourced from Glottolog. Cultures in blue (n = 83) are included in the Standard Cross-Cultural Sample (SCCS), a global sample of 186 relatively independent societies.
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Roope Kaaronen @roopekaaronen.net · 12/03/2026
Did you know that the spinning top is one of the most common forms of traditional play worldwide? Our research found tops to be nearly universal across human cultures. Wherever you come from, your ancestors probably spun tops. New preprint: Top of the World osf.io/preprints/so... Thread:
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Roope Kaaronen @roopekaaronen.net · 12/03/2026
The logo of Posit (formerly RStudio), which you see every time you launch RStudio, looks a lot like the one of the most commong string figures worldwide. Also known as the Ancient Greek knot, Plinthios Brokhos Tetrakyklos. It's the one in my profile picture.
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Roope Kaaronen @roopekaaronen.net · 07/03/2026
Re. "some designs simply don't need to be improved." The Antrea net was knotted ca. 10,500 years ago. It's the oldest surviving fishing net, discovered in Karelia, (then) Finland. Back when the Baltic sea was a lake. It uses the same knots (sheet bends) as fishing nets, volleyball nets, today.
Bits and pieces of ancient cordage, part of the Antrea net.
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Roope Kaaronen @roopekaaronen.net · 04/03/2026
Ois joo.
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Roope Kaaronen @roopekaaronen.net · 13/02/2026
My office khipu grows. Practicing its different logics and many ways of representing data. One observation is how *tactile* reading the khipu is. A lot of the embedded information is aided by feeling the cord, and not just looking at it.
An Inka-inspired (but not reconstructed) khipu (or quipu) made from knotted cords of varying colours hanging in my office.
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Roope Kaaronen @roopekaaronen.net · 01/02/2026
Sunset run on the sea. I'll be kayaking this same route in two months. Helsinki can be really nice at times.
Sunset over the frozen sea.Frozen Baltic sea during daytime.
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Roope Kaaronen @roopekaaronen.net · 30/01/2026
Next to the string figures, of course.
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Roope Kaaronen @roopekaaronen.net · 30/01/2026
One of my khipus-in-progress now hanging in my office. It's definitely been fun to learn the ins and outs of the system. Honestly, more intuitive than expected (except for the nuances where scholars disagree).
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Roope Kaaronen @roopekaaronen.net · 29/01/2026
The frozen sea in Helsinki. Ten day forecast looks like we might be able to walk to the islands this February. Been a few years since the last time that was possible.
Frozen white Baltic sea in the sunshine.
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Roope Kaaronen @roopekaaronen.net · 15/01/2026
I read a lot of obscure books for my research. Such as this 1955 PhD thesis, which looks like it hasn't been opened in decades (ever?): it still had the invitation card for the post-defense reception inside. "RECEPTIE NA AFLOOP VAN DE PROMOTIE IN HET UNIVERSITEITSGEBOUW"
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Roope Kaaronen @roopekaaronen.net · 13/01/2026
More like:
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Roope Kaaronen @roopekaaronen.net · 12/12/2025
Worth it!
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