Begetting Maxwell's demon
Par taz le jeudi 29 novembre 2012, 07:00 - Science - Lien permanent
The best way to protect the future is to invent it.
Alan Kay
The rules of the Colloque Wright pour la Science, held every two years, are the following. During five evenings, worldfamous scientists present lectures of about 50 minutes followed by a round table discussion of the evening’s subject featuring all five of the week’s lecturers. Questions from the audience are discussed by the speakers and simultaneous translation from English to French and vice versa are provided throughout the program. The conferences are free of charge and open to everyone.
The previous editions were about:
- 2010: Quantum revolution (La révolution quantique)
- 2008: Great Epidemics (Grandes Épidémies)
- 2006: Climatic [r]evolution ([R]évolution climatique)
- 2004: Stem cells and regenerative medicine (Cellules souches et cellules régénératrices)
- 2002: Entering the Nano-world (Aux portes du Nano-monde)
This year's theme was Molecular architecture (Architecture moléculaire). We know that the matter that makes up the world we live in is made of atoms, but this simple statement is of limited use – it is like describing architecture by saying that buildings are made of stones. We would like to know how the atoms are arranged and put together, and how this can explain the astonishing variety of substances which we encounter and use in everyday life, including inside our own bodies.
In a presentation entitled The magic of molecular machines, David Leigh used entertaining magic tricks to explain how scientists use nature's nanotechnology to do creative synthetic chemistry. By developing controlled translational motion (catenane) and controlled rotational motion (rotaxane), researchers are able to manufacture molecular switches, building blocks for a molecular information ratchet (paper) that employs a mechanism reminiscent of Maxwell's demon. It is however powered by an external source (light) hence does not challenge the second law of thermodynamics.
Maxwell's demon is a fundamental Gedankenexperiment in science, where a demon uses information to split lukewarm water into hot and cold water. After a seminal letter from James Clark Maxwell to Peter Tait (1867), subsequent analysis by several generations of scientists revealed a fundamental link between entropy and information, significantly influencing the development of statistical and quantum physics and chemistry, information theory and computer science.
Leigh's final consideration: Chemistry is a bit like love, there is a special one for every one of us. But sometimes, anything will do.
Maxwell's equations have had a greater impact on human history than any ten presidents.
Carl Sagan
13 derniers coms