Siffre's underground experiment

On September 14, 1962, the team remaining on the surface informed Michel Siffre that the experiment was completed. The 23-year-old speleologist thought it was August 20. He was missing 25 days, lost in the dark, without a watch, on an underground glacier.

Siffre's scientific goal

A speleologist and geologist, he had descended alone on July 16, 1962, into the Scarasson chasm. His idea was summarized in one sentence: to study his own wake-sleep cycle in the absence of any temporal reference.

Siffre's experiment results

He carried neither a watch nor a clock, and nothing informed him of the time, day, or night. The experiment officially began the day after his descent, and it laid the foundation for what would later be called the "out of time" experiments.

Location of the Scarasson chasm

The Scarasson chasm is located in the Marguareis massif, on the French-Italian border, but on the Italian side: in the commune of Briga Alta, in the Piedmont region. It overlooks La Brigue and Tende, two neighboring French villages, which explains why it is often thought to be on the French side.

Details of the chasm

The depth varies according to the accounts. In his book, Siffre mentions approximately 130 meters, while other documents mention rather 100 meters. The underground glacier where he settled extends between -100 and -130 meters, which reconciles the two versions approximately.

Conditions inside the chasm

The conditions, however, leave no room for discussion. The temperature there remains below zero, the humidity reaches about 98%, and daylight never reaches there. Regular rockfalls have regularly endangered the young man, according to the account he published in 1963.

Siffre's motivation

Why this glacier? A year earlier, Siffre was looking for ice in the massif and had discovered this buried mass in the Scarasson. The space race, which at the time opposed the United States and the Soviet Union, fed his reflection on isolation: living underground without references was a bit like training to live far from Earth.

Communication during the experiment

A one-way radio. Siffre was not completely cut off, but communication only worked in one direction. He called the surface by radio to signal the major moments of his life: waking up, meals, going to bed.

Siffre's internal clock

His wake-sleep cycle lasted approximately 24 hours and 30 minutes, that is, half an hour longer than the solar day. Left to himself, the human body does not stop: it follows an internal clock slightly offset from the sun.

Perception of time

The mystery of the 25 days remains. A cycle of 24 hours and 30 minutes is not sufficient to explain it, and it is here that the perception of time comes into play. Accounts of the experiment report, for example, that a task supposed to last 2 minutes took him more than 5.

End of the experiment

The announcement of the end took place on September 14, but the ascent did not take place until the 17th. Three days of delay, which explain why some accounts retain one date or the other as the final point.

Siffre's return

Siffre emerged from the chasm exhausted, out of strength. He was given large opaque glasses over his eyes to prevent him from being blinded by the light he had just regained. He was then carried on the back of a man to the base camp.

Evacuation and aftermath

An helicopter then evacuated him to Nice. For a 23-year-old man who had just spent about two months underground, the return to normal began with a medical evacuation. The long-term "out of time" experiments had just been born.

Siffre's documentation

The follow-up confirmed the scientific interest of the experiment. Siffre wrote a book published in 1963, Out of Time, which recounts the descent into the Scarasson from the inside.

Later experiments and legacy

He later repeated the experiment on invitation from NASA. Others followed his footsteps, up to the "Deep Time" experiment conducted by Christian Clot, who voluntarily confined a group underground, far from any clock.

Siffre's death

Michel Siffre died on August 24, 2024, at 85 years old. As for the exact duration of his first descent, the accounts give 60, 61, or 63 days depending on whether one counts from the descent or the official start of the experiment, and depending on whether one stops at the announcement or the ascent. Hence the cautious expression found everywhere: approximately 2 months.