Escape Hatch

Science is a funny business. Innovative science is autonomous, it rolls under its own steam; and yet science serves humanity, and doesn't intend to roll over anyone. The products of science should be freely available. To this end, I support the GNU Free Documentation License, which is an extended version of the GNU Public License for Open Source software. Excepting links to possibly copyrighted material originating elsewhere, the text and images on my website can be used freely, within the restrictions of this license (for example, they can be incorporated into GNU-licensed free encyclopedias such as Wikipedia). If you have a website yourself, please add a message like this to your own web pages to promote free access to knowledge (see Wikipedia's instructions).

Albert en Laura

Als je wilt weten wat de overeenkomst is tussen Albert Einstein en Laura Dekker, kun je hier een antwoord vinden, afkomstig van De Wereld Draait Door op 1 september.

Het weer in het Heelal

Ter gelegenheid van het International Year of Astronomy 2009 ben ik bezig met het thema Het weer in het Heelal. Het dagelijkse tv-programma De Wereld Draait Door gaf mij de kans het eens te proberen, en nogmaals op 12 mei 2009. Mijn werk aan publiekscontact komt hier goed van pas.

Alien Art

My activities in the arts have been bundled under the title Alien Art. If you're interested in finding out about the sort of work I do, you may click here. The web site is brand new, and more content will be added soon.

Koude en Kunst

De vermetele die mijn openingstoespraak voor de tentoonstelling Een familie in koude en kunst in het Leids Stedelijk Museum "De Lakenhal" nog eens wil horen, kan hier een digitale opname vinden in MPEG4-audio formaat.

The Riddle of the Red Rectangle

Upon the request of our Masters students, I have taught an extra half-semester course on Computational Dynamics. The lectures covered the physics of self-gravitating point masses, corresponding mathematical properties of such systems, astrophysical applications, and practical exercises using an educational version of Simon Portegies Zwart's computer code. Knowledge of classical and statistical mechanics, ordinary differential equations, and some computer programming (preferably C) is a prerequisite.

The web site of this course has now been completed.

This course was given in conjunction with Dr. Clovis Hopman's course on Stellar Dynamics.

The course provides a review of modern cosmology, with emphasis on the early stages of the Universe, in particular the era in which radiation and matter were strongly coupled. We discuss the homogeneous and isotropic Friedmann models, and briefly consider their observables in the local Universe. This provides the basis of observations in the expanding Universe, and the present-day best guesses of the parameters that govern the expansion. The standard model for the hot Big Bang is subsequently described, including the physical processes in the early Universe, such as inflation, baryogenesis, and nucleosynthesis. Next, a survey is made of the properties of the constituents of the cosmological fluid. These include the various radiation backgrounds, and the visible and dark matter. The properties of the surface of last scattering are discussed, as well as the structure in the local Universe, and the processes that led to its formation. Finally an overview is given of the results of recent observational campaigns that constrain the cosmological parameters.

Recommended Book: P. Coles & F. Lucchin, Cosmology, 2nd Edition, Wiley 2002

The web site of this course will be updated as necessary.

The title of my contribution to the annual Netherlands Astronomers' Conference is Shock Patterns in Eccentric Mass-Losing Binaries. The corresponding poster can be found here.