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Illustration of a black ice cream cone
Illustration by Sandbox Studio, Chicago

Celebrating Dark Matter Day in Latin America

Scientists, artists, communicators and physics fans find creative ways to mark the unofficial holiday devoted to dark matter.

In the United States, October 31st is synonymous with the unknown, spooky and strange. While some Americans dress as witches or skeletons or decorate their houses with spiderwebs or ghosts, around the world people are celebrating something even more bizarre—dark matter.

Unlike stars, planets, gas, dust, asteroids and comets, dark matter does not emit or reflect light. Instead, we see its gravitational influence on its surroundings.

Since 2017, various institutions have organized events in October to celebrate Dark Matter Day. Today, Symmetry highlights the unique ways people acknowledge this cosmic mystery in Latin America.

Mexico: Life, death and dark matter

In Mexico, science communicators Judith T. Jimenez and Elisa Medina are helping spread the word about dark matter. Jimenez and Medina are part of the outreach team for the future neutrino observatory Hyper-Kamiokande, currently under construction in Japan.

Scientists from Mexican institutions—including the Instituto Tecnológico de Estudios Superiores de Monterrey and Universidad de Guadalajara—participate in the Hyper-K collaboration. Hyper-K, scheduled to start operation in 2027, is designed to study particles called neutrinos, but some Hyper-K research will also be able to address questions related to dark matter, such as whether dark matter particles might annihilate one another and, in the process, produce an excess of neutrinos.

For Dark Matter Day this year, Outreach Hyper-Kamiokande Mexico will mingle this enigmatic matter with a bit of Mexican culture by asking people to write poems inspired by calaveritas. Calaveritas (or calaveras literarias, which translates to “literary skulls,”) are satirical poems usually written for Día de los Muertos, the Day of the Dead, which is observed in early November.

Traditionally, calaveritas, which often take the form of a fake eulogy, poke fun at death, life, and the transitory nature of human existence. For Dark Matter Day, dark matter fan Jesús Gerardo Gallegos Sifuentes wrote in remembrance of physicist Fritz Zwicky, the scientist who postulated the presence of dark matter:

Surrealista alguien le llamó,
Por olvidar el modelo tradicional,
Hasta que alguien más calculó
La velocidad orbital.

Surreal someone called him,
To forget the traditional model,
Until someone calculated
The orbital speed.

“The journey with Dark Matter Day has been truly remarkable, centered on the exploration of the intriguing world of dark matter and the infectious enthusiasm it has sparked,” Jimenez says.

Argentina: Art, games and mysterious flavors

For Dark Matter Day, Planetario Galileo Galilei in Buenos Aires will give audiences a chance to “see” dark matter with a screening of The Phantom of the Universe, a show on the search for dark matter created by the European Space Agency. This will be the planetarium’s second such event, accompanied by public lectures by scientists.

“A common misunderstanding is the perception that dark matter is entirely enigmatic and that we have no clue about its nature,” says Estefania Coluccio Leskow, a scientist and manager of the planetarium. “While we have not yet directly detected dark matter, we have amassed compelling observational evidence that strongly supports its existence.”

Celebrating Dark Matter Day has also become a tradition for artist Sebastián Verea, the director of Música Expandida at Universidad Nacional de San Martín in Argentina. Verea works with resident artists to create anything from videos to sound installations inspired by the search for dark matter. Pieces have been displayed in festivals around the world, from Argentina to Portugal, and at the university’s art-science conference. “Art makes possible poetry and imagery that push the boundaries of what can be envisioned, modeled, and tested,” Verea says.

This year, Xavier Bertou, a scientist at Centro Atómico Bariloche, and María Belén Lovino, a science communicator at Comisión Nacional de Energía Atómica and a physics professor at the Universidad Nacional de Río Negro, discussed Dark Matter Day with an Argentinian collective of artists and designers, Colectivo de Diseño.

Both Bertou and Lovino are involved in the planning of the Agua Negra Deep Experiment Site (ANDES for short). To be situated in the 1,700-meter underground Agua Negra Tunnel between Argentina and Chile, the laboratory could host experiments that search for dark matter.

Their discussions with Colectivo de Diseño led designers to create several dark matter-inspired products, including a dark-matter puzzle. The puzzle is black on both sides, and every piece has a corner, making it especially difficult to figure out.

Bertou says he sees Dark Matter Day as a chance to discuss with members of the public how science is done and how scientists think. “The main aim is more to put people in contact with science, [and] to put people in contact with scientists.”

In 2022, Bertou, who loves card games, was involved in creating a 20-card expansion of the cooperative game Arkham Horror, as part of its Dark Matter Campaign. The expansion allows players to use real scientific facts in their efforts to solve a mystery and defeat Lovecraftian monsters bent on destroying the world. This year, Bertou is working on an expansion for the card game Marvel Champions in which a supervillain, Graviton, will use dark matter to manipulate gravity.

And in their most delicious promotion for Dark Matter Day, the ANDES scientists teamed up with a local ice cream shop, Rudolf Helados, to create a smooth, black “dark-matter ice cream.”

“The formula is secret,” Lovino says.

But it certainly isn’t chocolate. “I don't like chocolate,” she says. “I love this ice cream… for me, it's like blueberry or vanilla. There's a lot of discussion [as to the flavor], and we love it because this is like dark matter. It can be many things. Maybe it can be more than one thing, or maybe we are wrong.”

Matías Santa Ana is a high school teacher in Bariloche, Argentina, who attended the unveiling of the dark-matter ice cream. As part of the presentation, he saw “beautiful images” of the universe and actual equipment scientists use to study dark matter. “I have some knowledge about dark matter,” he says. “But after the event, I went home knowing a lot more.”

Connecting children and scientists

For the past three years, school children across Latin America have celebrated Dark Matter Day in a special way. They have been invited to draw pictures or create art about dark matter. Children then send their art to scientists, who record their reactions to the art.

Physicist Carla Bonifazi—previously at the Instituto de Física at Universidade Federal do Rio de Janeiro, and now at Universidad Nacional de San Martín—coordinated this effort last year in Brazil.

She says children were excited to see scientists commenting on their work.

“I believe the impact of [a scientist,] someone who is often seen as intangible, talking to them, commenting on what they had done, and giving them attention had a significant effect,” she says.

“The drawings were all fantastic. We believe they are true works of art, to the extent that many of them decorate the hallways and offices of some of our research institutions.”