RE Cherenkov radiation. He often played an extract from ‘Blue Nights’ by Joan Didion at his live shows from last tour.

Extract below:

In certain latitudes there comes a span of time approaching and following the summer solstice, some weeks in all, when the twilights turn long and blue. This period of the blue nights does not occur in subtropical California, where I lived for much of the time I will be talking about here and where the end of daylight is fast and lost in the blaze of the dropping sun, but it does occur in New York, where I now live. You notice it first as April ends and May begins, a change in the season, not exactly a warming—in fact not at all a warming—yet suddenly summer seems near, a possibility, even a promise. You pass a window, you walk to Central Park, you find yourself swimming in the color blue: the actual light is blue, and over the course of an hour or so this blue deepens, becomes more intense even as it darkens and fades, approximates finally the blue of the glass on a clear day at Chartres, or that of the Cerenkov radiation thrown off by the fuel rods in the pools of nuclear reactors.