I was sitting in the lecture theatre of the Royal Institution at the Science Online London meeting (of which I hope to write more later, but you can retroactively follow the day’s tweets or just search for the day’s tags) when I realized I had missed the fifth anniversary of this blog this past July. So: thanks for your attention for over 400 posts on cosmology, astrophysics, Bayesian probability and probably too much politics and religion.

Today is also a much more important date: the 400th anniversary of Galileo’s telescope. Even Google is celebrating.

Right now, I’m at a meeting in Cambridge discussing Primordial Gravitational Waves — ripples in space and time that have been propagating since the first instants after the big bang. Despite my training as a theoretical physicist, I’m here to discuss the current state of the art of experiments measuring those waves using the polarization of the cosmic microwave background, which probes the effect of those gravitational waves on the constituents of the Universe about 400,000 years after the big bang. Better go finish writing my talk.