Prof. dr. Wubbo J. Ockels is a Dutch physicist, and also the Netherlands' original astronaut. He is a Professor of Aerospace Sustainable Engineering and Technology at the University of Delft, and tries to stimulate a mentality change among Dutch citizens.

In his mind-bending TEDxAmsterdam talk, Ockels explains how ‘time’ is created by human beings, as a way our brains can make sense of gravity. The speed of light is constant, because it is made by us: it’s the clock by which we have calibrated our existence. Based on this premise, Ockels proposes a new way to explore life in our galaxy.

More at tedxamsterdam.nl/2009/video-wubbo-ockels-on-time-and-gravity/