Speaker: Hans Mooij, Judith Klumperman and Rienk Eelkema
Department: Quantum Nanoscience TU Delft, Cell Biology UMC Utrecht, Chemical Engineering TU Delft
Subject: The Nobel prizes in the physical sciences 2016
Location: Delft University of Technology
Date: 1 December 2016
Author: Romano van Genderen
As the pre-program of the Kavli colloquium, the findings of the researchers that earned the 2016 Nobel prizes were explained by three scientists in the same field as these researchers. It was also discussed how important and influential these researchers were and whether or not the Nobel prizes were deserved in their eyes. I will also mention whether or not I consider these researchers to be deserving of these prizes.
Firstly, the research that earned the Nobel prize in Physics, awarded to D J Thouless, D M Haldane and J M Kosterlitz, was explained by professor Mooij. This talk was about how the mathematical field of topology was used in quantum physics to predict certain new phase transitions and states of matter. The first thing he mentioned was the standard example of “topology for beginners”, namely the talk that a donut and a coffee cup are basically equal to a topologist, both being homeomorphs of one another. This means that both essentially have the same characteristic, namely having a single hole; or, slightly more mathematically, that in both cases you can place a circle in the space and not always be able to contract it into a single point (because, of course, the hole gets in the way). Next he showed us three kinds of researches where the field of topology was applied to physics. Firstly, he showed that a situation with one vortex and one anti-vortex in liquid helium is topologically equivalent to no vortexes at all. Next, he showed using a topological identity for solving a surface integral that the Quantum Hall Effect allows us to model a 2D fluid layer inside a perpendicular magnetic field as a 3D solid. Finally, he used a topological identity to show that conductance in all sorts of matter is quantized, that there are distinct “channels of conduction”, that can either be open or closed. This final insight will most likely have large applications in improving transistors, which are slowly getting too small for classical physics to be relevant.
I think this research does really deserve its prize, since it uses a rather new branch of mathematics to solve physical problems. It shows promise that topology will be a likely candidate for the “Calculus of the New Millennium”, the framework in which large parts of physics will be built up.
Secondly, professor Klumperman explained the research by Y Ohsumi on the mechanisms of autophagy, which earned him the Nobel Prize in Physiology or Medicine. Autophagy can be described somewhat basically as the cell “eating parts of itself”. This mechanism is used for breakdown, removal and recycling of intracellular proteins. The pathway works by sending out an isolation membrane, a small piece of double membrane that grows and engulfs the proteins that have to be removed. It then fuses to the lysosome, where the vesicle opens up into the lysosome, which breaks down the components. This process is very strictly regulated by genes such as LC3, now considered the master gene of the whole pathway, and PI3K. This pathway plays a role in a plethora of physiological processes, such as reshaping the developing embryo, neurodegenerative diseases such as Alzheimer’s or Parkinson’s disease, and cancer. The trick Ohsumi used to identify this very fast and illusive process was very ingenious, using genetic modification to make yeast cells that do not destroy the autophagosome filled with proteins when it fuses to the lysosome.
Due to this very clever trick, I think Ohsumi totally deserves this prize, since it took years of effort and devotion to find this hidden, but still very fundamental pathway. I expect the applications of the knowledge of this pathway to be groundbreaking.
Fig 1: Autophagy pathway. It can be seen that the isolation pathway engulfs a protein and fuses with the lysosome (graphic made by Patients Against Lymphoma)
Finally, professor Eelkema of the Department of Chemical Engineering discussed the Nobel prize winning research of JP Sauvage, J Fraser Stoddart and Dutch scientist B L Feringa on molecular motors, devices that show controlled motion. He dealt with the three scientists in chronological order.
Firstly, he explained that Sauvage was the first person who built a controllable molecule, namely catenane, using a new method using a copper ion as a template. This is a molecule consisting of 2 interlocked carbon rings. The strength of association of these two rings, and therefore their distances, can be regulated using electrochemistry. He linked all these chain links together to form a molecular muscle which can be contracted and released at will.
Fig 2: Structure of catenane
Secondly, he talked about the findings of Stoddart, namely inventing rotaxane, a molecule shaped as a ring on a dumbbell. This shape allows the ring to slide on the shaft of the dumbbell, but the ring is not able to get off the dumbbell. This was used as a molecular shuttle, as electronic memory and most importantly to perform macro scale work.
Fig 3: Structure of rotaxane
Thirdly and finally, with a lot of Dutch pride, he mentioned the work of Ben Feringa, who made molecular rotors driven by light. He did this by improving a Japanese design, which moved too slow for practical use. This molecular rotor was eventually applied as something called a molecular car, but he did not have enough time to explain this.
Fig 4: Structure of the molecular rotor made by Feringa et al
This is the only prize I do not consider that well-deserved. It is of course nice that these sorts of molecules can be made, but unfortunately, I do not see any possible applications of it that cannot be achieved using current-day electronics. If these machines were to be controlled using nanoscale currents, I might see some use in it, but these devices are far too basic to do even basic logical operations. But this field is also the field that is most distant to mine, which might influence my opinions.