Einstein's theory of relativity has revolutionized our understanding of time and space and their relation to each other. What we know about spacetime, time travel and the like is summarized in this lecture. [more]

On 14 September 2015, a new age of astronomy began. Since then, we have been observing the universe in a completely new way: with gravitational waves. [more]

Albert Einstein's theory of relativity is one of the pillars of modern physics. Inititally developed from thought experiments, it is now supported by a large number of different experiments and observations. It is therefore one of the most stringently tested physical theories. We take a look at the foundations and observed predictions of this theory. [more]