I love working at NPL! Over lunch the other day I spoke with my colleague Richard Rusby about my doubts over the explanation I had read about the colour of the sea. This explanation stated that the sea is blue because water is ‘blue’. And the justification for this assertion was that molecular vibrations of the hydrogen in the H2O absorbed red light – a verifiable fact. However the colloquial justification of a nameless colleague was that if a vial of water was compared with a vial of ‘heavy water’ the ordinary water looked noticeable blue. Richard said that whenever I wanted I should ‘pop down’ and he would show me a vial of heavy water. Wow! It transpired that Richard had had a vial of heavy water around for many years without quite knowing what to do with it!
The Comparison and the Amazing Discovery
The comparison was disappointing because there is no noticeable difference in the colour of vials of heavy water and regular water. Normal water does not appear even slightly ‘blue’ when held against regular water. Clearly there is more to investigate here.
However the sample of heavy water was amazing!
First of all, it was stored in a solid wood block with a type written label stating it was made in 1935! Opening it up (see top picture) it was clear that it had been made at the Norsk Hydro plant in Norway. According the ever reliable Wikipedia this plant only began production in 1935. This was the same plant that was the object of a daring commando raid in the second world war to prevent the Nazi from creating a nuclear bomb. And I held in my hand a sample from the first year of production of that factory.
I felt shaky all afternoon. I had held a piece of history in my hands – an object that not so long ago people would have given their lives to possess. I still don’t know how to proceed about the colour of the sea issue, but I feel – astounded to have encountered a vial of heavy water of such esteemed pedigree. And it had been in a cupboard in my own department all these years! I love working at NPL.