I have long been interested in how we perceive time. There are many markers of time’s passage, daily and seasonal changes and biological changes being just some of them. Albert Einstein revolutionized our understanding of time by saying that physical time of an event is what is given by clocks placed at the location of the event, and then showed that the interval in clock readings between any two events depended on the state of motion of the clocks.
But there is also the psychological perception of time, the sense of how much time has elapsed when one has no external means such as a clock or diurnal rhythms to keep track of it. In an experiment, 15 volunteers were kept in a deep cave for 40 days without any means of knowing the passage of time other than their sense of it.
The group lived in and explored the cave as part of a project called Deep Time. There was no natural light, the temperature was 10C and the relative humidity 100%. They had no contact with the outside world, no updates on the pandemic nor any communications with friends or family.
In partnership with laboratories in France and Switzerland, scientists monitored the 15 team members’ sleep patterns, social interactions and behavioural reactions via sensors. One sensor was a tiny thermometer inside a capsule that participants swallowed like a pill. It measured body temperature and transmitted data to a computer until it was expelled naturally.
The team members followed their biological clocks to know when to wake up, go to sleep and eat. They counted their days not in hours but in sleep cycles.
When they came out yesterday, their estimated time was around 30 days, with one person thinking it was as little as 23 days. As far as I am aware, no one thought it was longer than 40 days.
While interesting, I am not sure why they had to go into a deep cave to do this. Surely it would have been much easier to place them inside a sealed, climate controlled building? Was exploring the cave an important part of the experiment?