How long does a minute last?

The only way to communicate with his team on the surface was a phone that Siffre was supposed to use whenever he woke up, when he fed and before he went to sleep. His team was forbidden to contact him so Siffre had no idea what time it was outside the cave. On 14 September, the phone rang for the first time in the cave. The experiment was over and it was time to go upstairs. Siffre thought it was a joke. By his calculations, it should have been 20 August. How was it possible that his perception of time had a difference of almost double, to chronological time?

Siffre's brain did not measure the length of time in the same way as his wristwatch. Proof that we humans, calculate time very differently than the artefacts we created to measure it. We perceive time subjectively. And this perception can be altered by a huge number of unexpected factors, such as the simple rhythm of a song. When we are happy, time speeds up, when we are sad, afraid or bored, it slows down. Time flies when we immerse ourselves in an activity we like. And it seems to stop when we decide to focus our attention on time itself.

The way humans structure this abstract and invisible concept is surprising. We structure time through something much more concrete and very visible. Space. We need space to structure time. We cannot experience one without the other. We feel time in motion. For the human mind, space helps give structure to time. We use space and motion metaphors when referring to time to try to organise it. We say that Christmas is coming and time flies.

And what has happened in the last few weeks? We have remained stationary in the same space. Our movement was reduced and immediately our notion of time changed. It is very difficult for us to imagine the flow of time, without the movement in space. So we became confused. We have missed an important meeting, forgotten a special someone's birthday and often had difficulty understanding what day of the week it was. We are experiencing space and time as we have never experienced it before. And each of us is experiencing it differently. We realised that time is not linear and absolute and that the way we measure it is a convention. An agreement we made between us that a day should have 24 hours. And what happens when we break a convention considered unbreakable? Who would dare to question whether a day really has 24 hours?

The American physicist and mathematician, Mitchell Feigenbaum dared. When he was studying Chaos Theory, he wanted to experiment with randomness in his day. He decided to live a 26-hour day. After a week, his routines became completely out of sync with those of his colleagues at Los Alamos National Laboratory. One of the main people responsible for structuring one of the scientific theories with the greatest impact on our history, he made the most unlikely connections when he broke a powerful convention about time.

After a few days in the darkness of the cave, Siffre had completely lost track of time. Each time he connected with his team on the surface, he performed a test that revealed an unexpected discovery. He counted from 1 to 120, at the speed of one digit per second. It took five minutes to count to 120. He had experienced five real minutes as if they were only two.

Probably the biggest learning we will take away from this unique experience of time and space that we are living today, is that time is not so much about physics or the thermodynamics of quantum clocks, but it is about the way our human brains work. Time is this emotional connection we have to the events that pass us by. In the end, possibly the mystery of time concerns who we are more than the universe.

The way we organise our lives is the way we organise our time. Our relationships, our careers, our businesses, they are all structured based on our perception of time. We have now discovered that time is neither a commodity nor a homogeneous commodity and this discovery can have a colossal impact on our lives.

Perhaps now, we can finally understand the strange question that Swatch asked us 23 years ago, in this old ad "How Long is a Swatch minute?", and which until today has remained unanswered.