One of the greatest accomplishments in recent astrophysics is the creation of a model for the complete inventory of the universe. All the observational data tell us with extremely high certainty that ordinary matter (every particle ever detected by every person who ever lived) makes up only one fifth of all the matter there is. The rest goes by the popular name of dark matter. Because it is dark, dark matter has been notoriously hard to detect; it doesn't emit or reflect radiation such as light or heat, and it can have only the feeblest of interactions with itself and ordinary matter. So how do we know it is there? In this lecture, Professor Bradač will discuss how she observes and measures the properties of invisible matter with the use of Einstein's theory of general relativity. She will try to convince the class that the principles behind it are not rocket science and can be understood with the simple use of a wine glass.
