Mysteries: Cambrian and Dark Energy

Tonight, we take a look at two mysteries that keep sparking debates in their respective scientific communities: - The Cambrian Explosion: at the beginning of this period of our planet's history, the number of life forms and their complexity increased dramatically - both in terms of body plans and behaviours, with the emergence of ecological complexity, like predator-prey relationships. But why did it happen? - Dark Energy: Like Dark Matter, Dark Energy is a hypothesis, a way of reconciling observations with the laws of physics, especially gravitation. But what could this mysterious energy be: an unknown fundamental force, fields of particles, an energy of the vacuum, something else...?