Theoretical physicist Jim Al-Khalili explores why our sense of time may be incredibly misleading, including the idea that past, present, and future might all exist at once.

Everything ever seen — every star, mountain, and face — makes up less than 5 percent of the universe. Astrophysicist Janna Levin reminds us that the rest — dark matter and dark energy — is invisible, mysterious, and everywhere. We are the luminous exception in a universe of darkness.

"Asking the question of, "Where did the entire universe come from?" is no longer a question for poets and theologians and philosophers. This is a question for scientists, and we have some amazing scientific answers to this question."

"Asking the question of, where did the entire universe come from, is no longer a question for poets and theologians and philosophers. This is a question for scientists, and we have some amazing scientific answers to this question that have defied even the wildest of our expectations."

What drives the universe's expansion? Chemist Lee Cronin explains the theories linking time, space, and selection, providing a fresh perspective on this cosmic mystery.

Don’t fall into the determinism trap. Everything is, in fact, random, says chemist Lee Cronin:

If Einstein couldn’t solve the theory of everything, could anyone? Physicist Michio Kaku explains what it would take.

How the Big Bang gave us time, explained by theoretical physicist.

According to renowned physicist Christophe Galfard, physics can’t explain our universe - yet.