How much does the universe weigh? – How to make dark matter visible and what it has to do with cosmology

Time: Thursday, 11:00-11:45 – ENGLISH VERSION

Speaker: Prof. Dr. Hendrik Hildebrandt – Ruhr-University Bochum

Age of participants: High school

Short description: Have you ever wondered how much the universe weighs? Does this question make any sense at all? Are there theoretical predictions that can be verified with astronomical observations? Cosmologists use modern large telescopes to measure the sky and make use of the so-called weak gravitational lensing effect. By means of tiny distortions that can be detected in the images of distant galaxies, the mysterious dark matter is made visible. From this, the total mass of the universe and its distribution can be estimated. These measurements can be compared with measurements of the cosmic microwave background that maps the universe shortly after the Big Bang. The highly successful Standard Model of cosmology makes direct statements about how these two observations are related. Recent results reveal a discrepancy between these methods that could grow into a serious problem for the Standard Model. One possible solution to this problem would be to abandon Einstein’s cosmological constant and introduce a time-varying dark energy component.

Required previous knowledge: None