Professor Joseph Silk FRS embarks on an illustrious journey through the universe to explain the paradigm shift in todays scientific view on the physical expansion of space.
It was once inconceivable that the universe could be expanding. The static universe survived three thousand years of analysis and observation, to become enshrined as a cosmological solution to the equations of Einsteins theory of general relativity. Only after three decades into the twentieth century did a paradigm shift occur. This was based on observational data, but it was to take decades before the recession of the galaxies was accepted as the conceptual proof of the physical expansion of space. I will recount how the recession of the galaxies was first discovered and eventually accepted as a physical model for the expansion of the universe.