SPEAKER 1: This is a production of Cornell University.
SPEAKER 2: We have a special presentation by one of our panelists. Roald Hoffmann is a Nobel Prize winner, poet, chemist. It seems he has traveled far between the sciences and the arts. And without further ado, I'd like to introduce Roald Hoffmann. And the title of his PowerPoint presentation is The Chemical Imagination at Work in Very Tight Places.
ROALD HOFFMANN: Thank you, Susie. I'm very glad to be here. What I thought that I'd like to do is to show you an example of what a reasonable if not good presentation might be. And so I want to tell you something. What did I say I was going to talk about, Susie? Oh yes, it's something about high pressure, yes.
Well if I can have the first slide here, let me see if I can work this Nothing's happening. I see some young people in the audience. Could I have your help, please?
AUDIENCE: We've got it.
ROALD HOFFMANN: OK, thank you. So what I want to tell you something about the landscape of things at high pressure. At high pressure, incredible things happen. Just things, for instance, that substances like xenon, a gas normally, under high pressure becomes a high melting solid and eventually turns metallic.
Ionic substances such as cesium iodide, sodium telluride, maybe not salt, sodium chloride, also turn metallic. And molecules, which we normally think of as just stable molecules, a gas like carbon dioxide or nitrogen, some of the most stable things turn at high pressure in a kind of molecular alchemy into solids like quartz and phosphorus. Something went wrong with my chem drawing. Excuse me one second. I should have drawn it this way.
This is carbon dioxide. You see this kind of involuted multiple bonding, two double bonds here with high pressure. This is what I didn't draw right. Links up with this guy and links up with this guy.
Carbon becomes tetrahedral.
As we go on, incredible further things happen. And in fact, I'd like one of the things we'd like to do is work together with Neil Ashcroft. He had the idea of chemical precompression. The idea was that hydrogens, we'd like to make hydrogen metallic.
Hydrogen is in the interior of every planet. It is the most abundant element in the universe. And it is exposed to incredible pressures in there and probably is metallic and superconducting. And we'd like to simulate this in the laboratory. It's easy enough to do on a computer. Oh, I forgot to say something. Could we go back one slide, please?
Yes, I forgot to tell you that our aim is to make hydrogen metallic. And we will do this by squeezing it together in the presence of other elements such as silicon, germanium, tin, and lead. And then we will have the hydrogens bonded to the germanium and tin. And then they will be more likely-- They'll get closer to each other. And they'll get more likely to bond with each other.
In general, as a result of this work, we've come up with a hierarchy of responses to pressure in crystals. And I can make it in four points. The first thing that happens when you squeeze molecules is you penetrate the repulsive region of intermolecular potentials and squeeze out so-called Van der Waals space.
And the next thing that happens, after you have squeezed out that space, which is easy. The second thing is you, in order to get closer together, you have to increase the coordination of the various metals that are involved and the main group elements. So they have to form more bonds if they only had-- This is what happened in carbon dioxide. And they only had two bonds with each other. Now they have to form four bonds with each other. It's just like sardines in a can.
The next thing after that is you have to decrease the length of covalent bonds and also the size of onions, I'm sorry, anions. The final thing that happens is an entirely new world in which the chemical intuition is not going to work, a new world of electrons moving off their atoms. New modes of correlation, things that the Marquis de Sade could not imagine.
And now I come to the conclusion for my talk. The main thing to do while looking at materials under high pressure is just to have fun and get close together. Thank you very much.
MAX EVJEN: Hi, everybody. Thanks so much for laughing with us with that. I'd like to introduce Jofish Kaye and Holly Adams who are joining me, and also not least, Dr. Roald Hoffmann.
My name is Max Evjen. I'm the executive director of Redshift Productions. And what you just saw was a game that was actually completely improvisational, or mostly improvisational. We did on Friday discuss with Dr. Hoffmann the content of what he would be discussing. But the actual performance that you saw was improvised.
This was developed as part of a show that we produced in New York City that was developed with improv artists. And this is the kind of thing that we at Redshift do. We create performances as scientific outreach. And we also do training and assessment and creation of outreach activities.
So if you have any questions about what we do or about what you just saw, I'll be wandering around here. And you can ask me any questions you like. Thanks again. Thank you very much to Jofish and Holly and definitely Dr. Roald Hoffmann.
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Cornell chemist, poet and Nobel laureate Roald Hoffmann delivers a human 'PowerPoint' presentation featuring Redshift Productions to open the second annual Public Engagement and Science Communication Symposium at Cornell, May 13, 2008.
Sponsored by the Cornell Center for Life Science Enterprise, a NYSTAR Center for Advanced Technology, in collaboration with University Communications, the Office of the Vice Provost of Research and the Department of Communication at Cornell University.