### Gravitational waves / Elementary tour part 2: Making waves

In our universe, gravitational waves are produced in many different ways. Almost every occasion in which masses are accelerated leads to the generation of travelling space distortions, be it two heavenly bodies orbiting one another or stellar matter ...

### General relativity / Elementary Tour part 4: The light side of gravity

For the propagation of light, Einstein's theory makes a clear prediction: Light is deflected by gravity. Just as test particles move on the straightest-possible lines in curved spacetime (i.e. on spacetime geodesics), so does light. The most basic example: ...

### Relativity and the Quantum / Elementary Tour part 1: Relativity in the micro-world

Quantum theory and relativity theory are two products of the early 20th century, developed in parallel. Not surprisingly, physicists early on began thinking about the possibility of combining the two. Could one, for instance, formulate a relativistic theory ...

### General relativity / Elementary Tour part 1: Einstein’s geometric gravity

The key idea of Einstein's theory of general relativity is that gravity is not an ordinary force, but rather a property of spacetime geometry. The following simplified analogy, which substitutes a two-dimensional surface for four-dimensional spacetime, serves ...

### Black holes & Co. / Elementary tour part 1: Neutron stars and pulsars

Stars that are between five and forty times as massive as our sun end their lives in a spectacular way - not with a whimper, but a bang! Once their nuclear fuel is exhausted, there is an gigantic explosion called a supernova, in which the outer layers of the ...

### General relativity / Elementary Tour part 2: The cosmic dance

In this new picture, there is no gravitational force that masses exert on other masses. Instead, there are spacetime distortions. Spacetime in the presence of a mass is curved. In flat, empty spacetime, small test particles follow straight lines. However, ...