**Klaas Landsman (Radboud Universiteit Nijmegen)**

Waaier 3, 12:15 - 13:00

This talk is an attempt to explain the content and background of the spectacular Free Will Theorem of John Conway and Simon Kochen, which (among other places) appeared in the Notices of the AMS, Vol. 56, No. 2, Feb. 2009. Their mathematical reasoning fits into a long literature on possible hidden variables in quantum mechanics. It is based on a beautiful earlier theorem of Kochen and Ernst Specker from 1967, which in turn sharpened the very first no-go theorem for hidden variables due to John von Neumann (1932). However, the philosophical interpretation Conway and Kochen attribute to their result is, in my opinion, flawed and is even based on an elementary logical mistake. But enough of value remains!

**Klaas Landsman** (1963) has published 75 papers and 2 books on high-energy physics, the mathematical foundations of quantum theory, noncommutative geometry, and the history and philosophy of science.

He originally studied theoretical physics at the UvA, where he obtained his PhD in theoretical high-energy physics in 1989. Following research appointments at Cambridge, Hamburg, and Amsterdam, he was appointed full professor of Mathematical Physics at the UvA in 2001. He moved to Nijmegen in 2004, where he was initially professor of Analysis. Since 2007, he has occupied the new Chair in Mathematical Physics. Besides his research and teaching, he spent a considerable part of his time at Nijmegen on outreach towards school-children and national math policy (concerning both education and research).

For example, in 2005 he was the PI of the Fellowship of Geometry and Quantum Theory (GQT cluster), in 2008 he coauthored the Masterplan Toekomst Wiskunde, and from 2006-2008 he was a member of the Resonansgroep Wiskunde (Sounding Board for Mathematics Education) of the Dutch Ministry of OC&W (Education, Science and Culture). He has given hundreds of invited talks all over the world.