Philosophy of probability
Sylvia Wenmackers
You can read a short description of my project "Inexactness in the exact sciences" on the NWO website.
My research is on philosophy of science and epistemology (study of knowledge), with the concept of probability as the central theme.
Probability is represented mathematically as a function: there are a number of possible outcomes (events) and the probability function (P) assigns a certain weight to each of these events, the probability. At first sight, this may not seem to be a suitable topic for philosophical reflection, but the story is not as straightforward as it appears: when you choose to model a certain phenomenon (such as probability) in a mathematical way, you can do this in multiple ways. Different mathematical theories for one and the same phenomenon can lead to wildely different interpretations and connect to different intuitions. Enough material for a philosophical investigation! Together with prof. Vieri Benci and prof. Leon Horsten, I am working on a new basis for probability theory which uses infinitesimal (or infinitelly small) numbers. Our goal is to develop a new foundation for probability theory which is not only mathematically correct, but philosophically satisfactory as well.
Probability has become increasingly important in the sciences: in our current physical theory concerning the micro world, quantum mechanics, predictions in terms of probabilities play a central role, and in the social sciences the same holds for statistics. Even when we base our opinions and beliefs on scientific facts, we rarely end up with an answer in terms of certainty. Confronted with detailed information in terms of probabilities, it's still an open question what's rational for us to believe. For example: if the probability of rain is 90 percent, is it then rational to believe that it will rain? And what if the probability is 99 or 99.9 percent? This type of questions can be considered in the study of epistemology.
Another part of my research deals with social epistemology. Imagine a group of people each of which hold an opinion concerning a number of issues (with logical connections between them). When these people are allowed to communicate with each other, they may revise their opinions, but then it may happen that they come to hold an inconsistent set of opinion. (In other words, when a person revises his opinion on a few propositions, it may happen that these opinions are no longer logically connected to the person's opinions on other, related issues.) This type of opinion dynamics can be studied with computer simulaties, making use of techniques from statistical physics.
On my blog, I write about my current research (in Dutch).
Until 2009, I was working in the biosensor research group of IMO, which studies new materials in order to develop better biosensors. For example, thin films of diamond are synthetized by chemical vapour position (CVD) and applied as the transducer material for DNA sensors. Diamond has interesting optical, electronic and mechanical properties, which can be used for sensitive and real-time read-out. I was also involved with the bio-functionalisation of silicon and related carbon materials, such as carbon nanowalls (upstanding layers of graphene).
Starting from the bare surface of a solid-state material, the first step in making a biosensor is the functionalisation. We use photo-chemistry to covalently couple organic linkers to the surface. After this, DNA or other biomolecules can be anchored to the linker by crosslinker chemistry.
We need (surface sensitive) characterisation techniques to investigate the transducer materials before and after bio-functionalisation. We have many techniques available at Hasselt University, of which these are the most relevant for our biosensor research:
  • Confocal laser scanning fluorescence microscopy (CLSFM),
  • Spectroscopic ellipsometry (SE) in the infrared (IR) and in the ultraviolet to visual (UV-VIS) range,
  • Fourier-transform infrared spectroscopy (FTIR),
  • Sum frequency generation (SFG),
  • X-ray photo-electron spectroscopy (XPS),
  • Scanning electron microscopy (SEM),
  • Atomic force microscopy (AFM),
  • Contact angle (CA) measurements.
Plenty of acronyms! When I see a license plate, I am often reminded of some measurement technique. ;-)