<b>Fifteen volunteers spent 40 days inside a French cave without clocks, sunlight or phones and emerged believing only 30 days had passed</b>

• The Deep Time team, deep inside the Lombrives Cave in the French Pyrenees.
• Known as Deep Time, the project was led by French Swiss explorer Christian Clot through his nonprofit research group, the Human Adaptation Institute, and was designed to study how the human brain tracks time and how a group adapts psycho