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Office: 11 G 50, Irchel
Institute for Computational Science
I am a theoretical physicist in the Institute for Computational Science at the University of Zurich. I'm a Swiss-born, South African-grown hybrid. While not sciencing, I can sometimes be found photographing, cooking, jogging, learning languages, or drinking coffee. (I'm very very talented at this last one, actually - not so much at the rest.) These are a few of my favourite things. Quickly click here for relief.
pushing boundaries in...
Take a gas and drop the temperature. It'll turn into a liquid, but how? 100 years on, theoretical models explaining this process still give massive disagreement with experimental results. We know that the transformation is stochastically driven through the erratic formation of clusters, made up of molecules clinging together in droplets large enough that the free energy barrier is surpassed. But we know very little about the details. This phenomenon is a process ubiquitous in nature: playing a role in dust seeding in the formation of structure in the Universe, modern industrial processes, and in everyday occurances like the genesis of rain and mist. Despite this, the process is poorly understand due to the complex properties of the small clusters. We perform numerical experiments of the transition, through large molecular dynamics Lennard-Jones simulations. This is of service to understanding the reasons behind the shortcomings of the models, and aids in the selection of ingredients for future ones. Publications: 1, 2, 3, 4
In trying to understand gravitational waves, we independently stumbled upon a new way of thinking about how gravitational waves couple to a detector. Succinctly yet technically put: we solve the wave equation for electromagnetism in a curved space-time. Our approach makes few assumptions, and so can readily be applied to response calculations for the European Space Agency's planned eLISA satellite constellation. Publications: 1, (2 in preparation)
The next generation of ultra-portable atomic clocks are in delivery. Borne by Earth or Sun -orbiting satellite, these clock satellites will be capable of testing general relativity to unprecedented accuracy levels, even making measurements of phenomena we've never seen before. This will help us differentiate between theories of gravity. The European Space Agency mission proposal STE-QUEST, and even more recent talk of a possible joint European-Chinese mission GRESE means that this might actually happen. My code which calculates these signals (c and python) is available from the journal Phys. Rev. D website. Publications: 1, 2
Bubble formation in liquid happens when the liquid is superheated (or stretched). Bubble formation is important to a wide range of fields - the quark-gluon plasma to hadron gas phase change in the early universe, targeted drug delivery, dark matter detection, volcano fountaining, cavitation corrosion of water-exposed materials, stimulating accelerated healing of bone fractures, and even and flavour infusion of plant matter into alcohol in the kitchen. The underlying physics is complicated and badly understood: a non-equilibrium multi-body system, with analytical models living within the intersection of molecular dynamics, fluid dynamics and thermodynamics. However, viscosity, surface tension, and a few other thermophysical properties may be all we need to describe the process of bubble formation and growth. We perform molecular dynamics simulations of these kinds of systems to test these models, and design better ones. Publications: 1, 2, 3, (4 submitted, available shortly)
The primary topic of my doctorate was the galactic center S-Star system, and what they can tell us about the fundamental nature of gravity. These stars orbit the Milky Way's central supermassive black hole and are the on most relativistic ballistic orbits yet discovered. Their proximity to this four million solar mass Black Hole means that they reach speeds of 12000km/s. Their orbits are weirdified from the orbit geometries that Newtonian gravity predicts. Additionally, the light that these stars emit travels upon this warped spacetime on its way to us, inducing gravitational redshift before landing in our telescopes, and imparting information about this strange manifold to us. These stars offer a fantastic test-bed for gravity in one of the strongest regimes yet tested. Publications: 1, 2, 3, 4
In 1995, the first sure detection of a planet orbiting a star other than our own was made. Now we know of more than 2000 extrasolar planets, and the count jumps up by a few every week. The reason these planets are a big deal are because they help us understand planet formation better, and bring us closer to understanding life in the universe. My interest in them is slightly different. What is not so well known at the moment is that given the fantastic precision to which measurements are now being made, general relativistic precession of the planet orbits (just like observed with Mercury in our system) may become possible in the near future. I wrote a few notes on it some time ago.
List of publications
Doktorarbeit Clocks around Sgr A*
Masterarbeit Next-to-Leading Order antennae in LHC massive particle production (4-month Master's thesis)
Semesterarbeit The MOND paradigm: from Law to Theory (1-month mini project during Masters)
Bachelor Project Conformal Brans-Dicke gravity via a Branelike approach