Jürgen Ehlers
![At the award ceremony for the Charles University Medal in Potsdam, September 2007](https://upload.wikimedia.org/wikipedia/commons/0/0b/Juergen_Ehlers.jpg)
Ehlers' research focused on the foundations of general relativity as well as on the theory's applications to astrophysics. He formulated a suitable classification of exact solutions to Einstein's field equations and proved the Ehlers–Geren–Sachs theorem that justifies the application of simple, general-relativistic model universes to modern cosmology. He created a spacetime-oriented description of gravitational lensing and clarified the relationship between models formulated within the framework of general relativity and those of Newtonian gravity. In addition, Ehlers had a keen interest in both the history and philosophy of physics and was an ardent populariser of science. Provided by Wikipedia
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