I had learned about Cherenkov Radiation and its characteristic blue color at university. When, a couple of years later, the university had finished building a new research reactor, they had an open house day with guided tours. Of course I’d take one!

The new reactor was of the swimming pool type, and seen from the wraparound gallery above, you could easily mistake it for one. Except for the blue shimmer in the water.

Remembering my studies, my head went hot and cold. Hadn’t they said the reactor wasn’t operational yet? Or had I just assumed, because of the open day? ub So I hesitantly approached our guide and asked about the blue light, to which he answered in the most casual way you can imagine:

"Oh, that’s because of the Cherenkov Radiation."

Pause.

Laughter. Seeing the doubts in my eyes he had just been messing with me, and they had deliberately installed blue lights there to make the experience more realistic for the open day