TED: The universe on a string by Brian Greene

Professor of Columbia University Brian Greene explains Superstring Theory, which is currently the most promising unifying theory, i.e. attempt to explain all four fundamental forces of nature. The four fundamental interactions are: strong nuclear force, weak nuclear force, electromagnetic force, and gravity. Brian is a prominent popularizer of science, and is best known for hosting and narrating PBS documentary The Elegant Universe, which won a Peabody Award in 2003.

Original video on TED.com (might be better quality).

TED: Beauty and truth in physics by Murray Gell-Mann

Murray Gell-Mann talks about particle physics and the role of mathematics in theoretical physics, discussing what it means for a theory to be “beautiful” and whether elegant equations are more likely to be right than inelegant ones. Math and symmetry matter. Murray Gell-Mann received a Nobel prize in physics for his work on the theory of elementary particles.

Original video on TED.com (might be better quality).