Physicists and astronomers are agog. On Thursday, experimenters will report the first detection of a phenomenon that has been long predicted:bursts of gravitational waves generated by cosmic collisions of black holes.

Sadly it is not unknown for hyped-up scientific claims to be mistaken or exaggerated - claims of particles going faster than light, gravitational waves from the big bang, and so forth. I count myself a hard-to-convince sceptic. But what is being claimed will be the culmination of literally decades of effort by scientists and engineers with high credentials, and this time I expect to be fully convinced.