Last Monday Stephen Hawking gave a lecture at the George Washington University for the 50th anniversary of NASA. There he discussed the chance of a contact between our civilization and an extraterrestrial one. And he warned about the risks we may be facing.

Researchers who blog are a rare and endangered species.

As far as rarity is concerned, it is easy to understand why that is so. Scientific research is a round-the-clock occupation, not your regular nine-to-five job. If a researcher has spare time, he or she is expected to invest it in doing more research: for Science is a mission, not a job! Because of that, finding the time to do outreach in a blog, broadcasting recent scientific results, or just expressing one's views is a demanding challenge, especially when one also has a family to attend to.

Analogies are a powerful way to explain complicated scientific concepts. I use them as much as I can whenever I describe particle physics in this blog or when I give a outreach talk in a school. However, good ones are not always easy to find. One usually needs examples from everyday life, which are simple to describe and which do not possess distracting features.

Today I wish to try my luck with you, to see if you come up with an analogy which is better than the one I could find to explain a feature of weak interactions. I must say I am not dissatisfied with my own find, but it is always good to subject oneselves to external judgement.

This is to inform you of the new luminosity record set today by the Tevatron collider at Fermilab. The machine has been working excellently, improving its performance as the machinists found ways to obtain higher stacks of antiprotons, reducing inefficiencies in the transport of the beams from one accelerator to the other in the injection process, or finding better beam tunes. A painstaking work that brought increasing returns, it seems.