Ingemar Bengtsson

My name is Ingemar Bengtsson, and I have been a lecturer at Fysikum in Stockholm since '93 (and a professor since '00). My previous "career" was at Chalmers, CERN and Imperial College.

This is me (as drawn by Jörgen Hansson in '73)

The research areas that I like the best usually have something to do with geometry. General relativity is a favourite. Most of my work there is on black holes. My strongest prejudice is that the world has four dimensions; this is the direction in which I look for clues about quantum gravity. Then I work on quantum information theory, since the geometry of the space of quantum states is wonderful and rather mysterious. What I find fascinating about relativity and quantum mechanics---as it happens, the two deepest theories we have---is that their basic equations have been around for a century, and yet they keep springing conceptual surprises on us. I am looking for the next surprise there, but I do keep a weather eye open on other subjects as well.

There are two things on my mind at the moment: An unexpected connection between quantum mechanics and the deeper recesses of number theory, and the localisation of energy in relativity.

I am told that some scientists think that there is something queer going on in the Universe while others, on the whole, don't. I tend towards the former viewpoint, but this is probably not apparent from my published papers. Some examples of those are:

• Note on Massive Spin 2 in Curved Space(1994)
• 2-Form Geometry and the 'tHooft-Plebanski Action (1995)
• Galactic Rotation Curves (1996)
• Black Holes and Wormholes in 2+1 Dimensions (1997)
• A Spinning Anti-de Sitter Wormhole (1998)
• De Sitter Space and Spatial Topology (1999)
• 2+1 Gravity, Chaos and Time Machines (2000)
• CPn, or, Entanglement Illustrated (2001)
• How to Mix a Density Matrix (2002)
• Geometry of Black Hole Thermodynamics (2003)
• Birkhoff's Polytope and Unistochastic Matrices, N = 3 and N = 4 (2004)
• Anti-de Sitter space, squashed and stretched (2005)
• Mubs and Hadamards of order six (2006)
• Note on non-metric gravity (2007)
• A note on trapped surfaces in the Vaidya solution (2008)
• Pentagrams and paradoxes (2009)
• The region of trapped surfaces in spherical symmetry, its core, and their boundaries (2010)
• The monomial representations of the Clifford group (2011)
• Families of complex Hadamard matrices (2012)
• Trapped surfaces in Oppenheimer-Snyder black holes (2013)
• States that are far from being stabilizer states (2014)
• Clifford tori and unbiased vectors (2015)
• A toy Penrose inequality and its proof (2016)
• Dimension towers of SICs. I. Aligned SICs and embedded tight frames (2017)
• Black hole lattices under the microscope (2018)

Well, it goes on. I wrote my best paper this year. Of course, not all my papers are published.

• Why is Space Three-Dimensional?

If any youngster wants to see what a "preprint" used to look like, here is one:

• Cubic interaction terms for arbitrary spin

With Karol Zyczkowski from Krakow I have written a book on quantum mechanics, seen through our eyes. The Cambridge University Press published the second edition in 2017:

Geometry of Quantum States

I occasionally try to write popular science articles. They are all in Swedish:

• Astronomen mot strömmen
• Kvantmekanikens historia
• Evighetsmaskiner, tidsmaskiner och kvantdatorer: Om fysikens gränser för avancerad teknologi
• Hur Roger Penrose transformerade relativitetsteorin

If you want to hear me trying to explain gravity (på svenska), you can do it from home.

My views on teaching happen to be identical to those of Fred Hoyle, as expressed in " The Universe: Past and present reflections " (Ann. Rev. Astr. Astrophys. 1982), so there is no need to repeat them here. This academic year I teach Electrodynamics:

· Elektrodynamik I. The book for the course is no less than that of J. D. Jackson, 3d ed. For the details see the course homepage .

I enjoy supervising Master's Theses and such things. I have made a little collection of all theses that I saved the pdf files for on a special thesis page.

Examples of lecture notes:

• Electrodynamics (for undergraduates)
• General relativity (for undergraduates)
• Analytical mechanics (for undergraduates)
• Constrained Hamiltonian Systems (for graduate students)
• Geometry of Quantum Mechanics (for graduate students)
• Anti-de Sitter Space (for graduate students)
• Quantum Electrodynamics (for graduate students)
• SL(2) (for graduate students)
• Spherical symmetry and black holes (for graduate students)
• A second relativity course (for master's and graduate students)
• Quantum Information (for master's students)
• Comments on Jackson (for undergraduates)

My present graduate student is Ole Sönnerborn.

My Erdös number is 3. My Einstein number is 4. My Bohr number is 3. And one more thing. A quote from James Lovelock, which I have had occasion to think about, quite some time ago actually:

"Of all the prizes that come from surviving more than fifty years, the best is the freedom to be eccentric."

Many years later in Meknes. Photograph by Adan Cabello.

Email:

ibeng@fysik.su.se

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