Halloween 2026 at CNRS: an escape room and talks in a château in Essonne

For Halloween 2026, the CNRS opens the doors of Button Castle in Gif-sur-Yvette on Friday, October 30, from 7 p.m. to 11 p.m. This second “Terrifyingly Scientific Evening” brings together three roundtables on the afterlife, mummies, and dark matter, plus an escape room focused on bats. The event is only available by registration, starting September 21, 2026.

After a first edition organized in 2025, the CNRS is back with a Halloween night during which the strange goes under the microscope. The public is invited to temporarily breach the gates of the château de Button, located on the Gif-sur-Yvette science campus, to meet researchers from nine laboratories on October 30, 2026.

There isn’t a traditional haunted house or a parade of blood-soaked creatures: the program instead leans on our biggest fears and the riddles that spark the imagination to probe the world around us. What do we really know about death? What can mummies still reveal? How do scientists track invisible matter in the cosmos? These questions anchor an evening where curiosity leads the way.

Three panel discussions at the crossroads of science and mystery

The first session, titled "At the Threshold of the Afterlife: Between Science and Belief", will run from 7:00 to 8:00 p.m. Ghosts, biological processes, reincarnation, and phenomena deemed unexplained will be tested against the tools of research. The debate will bring together Damien Charabidze from the Centre d’histoire judiciaire, Stéphane Charpier from the Institut du cerveau, and Grégory Delaplace from the Centre de recherche sur les civilisations de l’Asie orientale.

This discussion will, among other things, explore how science, history, and the study of beliefs illuminate our relationship with death. It’s not about proving or debunking the existence of ghosts in any blunt way, but about unpacking the stories, perceptions, and mechanisms that shape our notions of the afterlife.

From 8:30 to 9:30 p.m., visitors can join the roundtable discussion Under the Bandages, the Mummies Unveil Their Secrets. Behind their fearsome image, these preserved bodies are valuable archives for studying ancient civilizations, funerary practices, the materials used in mummification, and the conditions that keep them preserved.

Today’s techniques let researchers study these artifacts without necessarily damaging them. Didier Gourier, from the Paris Institute of Chemical Research, Maguy Jaber, from the Laboratory of Molecular and Structural Archaeology, and Roberto Vargiolu, from the Laboratory of Tribology and System Dynamics, will outline the tools used to make these remnants speak centuries after their creation.

Finally, the evening will take on a cosmic dimension from 10 p.m. to 11 p.m. with "Dark matter, this obscure cosmic mystery". Invisible and still very hard to detect, dark matter would account for about 84% of the matter present in the cosmos. Its existence is inferred from its gravitational effects, but its nature remains one of the major questions in contemporary physics.

Researchers Xavier Bertou, Julien Billard, Yoann Kermaidic and Julien Lavalle will outline the clues scientists have been chasing, along with the experimental ideas devised to try to detect this elusive matter. A fitting finale to the evening, as we cast our eyes toward the darkest corners of the Universe.

A science-themed escape room about bats

The escape game "The Secret of the Bats" returns for this 2026 edition. The plot drops players into the fictional laboratory of Dr. Vanderbruck, a bat specialist who hastily headed to Patagonia just as he was on the verge of a major breakthrough.

Before his departure, the researcher left behind unfinished experiments that participants will have to try to salvage. Gathered into teams, they will have to solve a series of enigmas while uncovering the CNRS research on these nocturnal mammals, their behavior, and their role in ecosystems.

Four time slots have been announced—7 to 8 p.m., 8 to 9 p.m., 9 to 10 p.m., and 10 to 11 p.m.—with two sessions planned for each slot. Tickets are expected to run out quickly this year, especially after the 2025 edition sold out in no time.

How to participate in CNRS's Halloween party?

The Frightfully Scientific Evening will be held on Friday, October 30, 2026, from 7:00 to 11:00 p.m., at the Button Castle, on the CNRS campus in Gif-sur-Yvette, in the Essonne department.

Registration is required to participate. Reservations will open on Monday, September 21, 2026, from the event’s official page. Access details and any activity-specific conditions will be announced at the time of registration.

This second edition offers a singular way to celebrate Halloween en Île-de-France: the strips conceal scientific information, bats become the heroines of an investigation, and the darkness guides you to the mysteries of the cosmos.

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