These two bits of scientific thinking impressed me a lot: Dark energy and flat Universe exposed by simple method and Cosmos may show echoes of events before Big Bang with links to the original papers that I like to have explicit rather than search for. The first, as the article title suggests, is a method to determine the large-scale geometry of space-time. Is it flat (so we can use Euclidean geometry) or is it curved (so we have to use a non-Euclidean geometry). What impressed me is the simplicity of the analysis. There is an assumption that the inclination of orbits of binary galaxy systems that we observe has no bias for any angle, but from that the flatness of space-time and the proportion of dark energy in the overall Universe mass is obtained. My ‘lay’ question on this is that we need to know what theories that amend general relativity to avoid the existence of dark energy would predict.

The second report is of work done with Roger Penrose, a very creative thinker. I had always assumed that if the Big Bang theory is really the way our world came into existence we would have no way of knowing anything about what was before the Big bang. This is so if you take the conventional view of the event, but Penrose does not like the instant inflation that current models need (the Penrose view suits me) and has a model of the Universe where the Universe preceding ‘this’ one produces the effect that inflation in the conventional model does. The papers author’s find non-uniformities in the microwave background radiation that can be related to the previous Universes and Big Bangs. We need alternative models in a similar way to test the ideas in the first paper mentioned above.