One of the exhibits was the Nobel Prize Certificate for the prize awarded to the younger Bragg. An elaborate looking thing from a distance and I forgot to take a closer look at the end. Plus various crystals and models, some of which had an illustrious pedigree.
The subject of the talk was an interesting group of materials - crystalline solids - called perovskites, named for a famous Russian mineralogist. The general idea being that you had an array built on the assembly illustrated above, with the red dots oxygen, the blue balls something reasonably straightforward. perhaps lead, and with the yellow balls quite possibly something quite complicated. In brief, ABX3, where A is blue, B is yellow and X is oxygen red. Part of the interest lies in what the blue and yellow balls are, part in where exactly the yellow balls are in relation to the fairly rigid grid of oxygen bound octahedrons in which they live. But tilting the octahedra was an option too. It seems that Glazer has had a happy & successful career devoted to them.
All kinds of interesting and useful materials can be made from perovskites, including, in particular, materials that can convert mechanical, heat or light energy into electrical energy, perhaps going the other way as well. One can, for example, pass infra red radiation through a lens to focus it on an array of suitable perovskites to give you seeing in the dark.
It also seems that they can come in the form of mixtures, which I am sure was not allowed when I was young. A crystal, almost by definition, could only be formed from a pure substance, from just one sort of molecule. Perovskites seem to break this rule big time.
Sufficiently complicated that making one of these up and then seeing what it can do is a better bet than trying to model the thing in a computer. Modelling is getting better all the time, but it is not yet a substitute for the real thing.
Glazer made the interesting observation that, when he started out, maybe 50 papers a year were published about perovskites, a number small enough that he could read all of them. Now the number is thousands. Perhaps there is a whole meta-science industry out there, people who make a living not out of doing basic science but out of trying to digest and make available other peoples'. An important activity, but not one which I would have found attractive. Doing stuff is the fun bit, not wading through reports, quite often quite badly written, of other peoples' fun.
There was quite a strong military smell about some of the work. But when asked about this, Glazer's response was that he just did the science. If other people did bad things with his science that was not his problem - which I thought rather glib and unsatisfactory. It might be a reasonable position, but one would hope that he would not sleep too well at nights if, for example, one of his inventions was used to kill lots of innocent people.
A good talk from an eminent scientist, but I did not think that he was entirely happy with popular science. I shall see how I get on with his 'Crystallography: A Very Short Introduction', a sort of Observer's Book of Crystals, oddly not available from Amazon and I was reduced to using Abebooks.
Thought to try the back way out of the lecture theatre, to find ourselves in a part of the building which was not dedicated to the public. Physical security a bit slack.
Goat before and Rifleman after. Wine in the first a good deal better than that in the second.
PS: wikipedia claims that Bernal's book 'Science in History' came in four volumes, whereas the book I had was just the one fat volume - and I don't think that my father would have bought the one volume abridged version from the Readers' Digest or the World Book Club. Abebooks seems to think the 1957 version came in one volume but offers no confirming picture. So yet another puzzle, perhaps to be solved by coming across a copy in an Oxfam shop.
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