His research interests are Yang-Mills gauge theories, supersymmetry, supergravity, quaternion and octonion algebras, spin structures, generalised theories of gravity, cosmological solutions, integrable systems and phase space quantisation.

Reduced phase space quantization constraints are solved first then quantized.

This phenomenon is known as space quantization.

For this reason, the name "space quantization" fell out of favor, and the same phenomenon is now called the quantization of angular momentum.

Otto Stern and Walther Gerlach show "space quantization".

This phenomenon, the quantization of angular momentum about an axis, was given the name space quantization, because it seemed incompatible with rotational invariance.

Since the electron was quantized to be only in certain positions in space, the separation into distinct orbits was referred to as space quantization.

With Otto Stern, Gerlach co-discovered space quantization in a magnetic field, the Stern-Gerlach effect.

This was called space quantization for a while, but this term fell out of favor with the new quantum mechanics since no quantization of space is involved.

Geometric quantization, Borel quantization, Mackey quantization, stochastic and phase space quantization, the problems of prequantization and polarization, deformation theory, dequantization.

However, with use of ideas involved in Dittrich's approximation scheme (built on ideas of Rovelli) a way to explicitly implement, at least in principle, a reduced phase space quantization was made viable.

Almost 80 years have passed since that time, but the problem of space quantization has still not been completely solved, although from time to time some researchers return to the topic, which confirms the ongoing timeliness of the problem.

The Bohr model was the focus of study, and Arnold Sommerfeld made a crucial contribution by quantizing the z-component of the angular momentum, which in the old quantum era was called space quantization (Richtungsquantelung).

However it is not fully equivalent to the Dirac quantization as the 'clock-variables' must be taken to be classical in the reduced phase space quantization, as apposed to the case in the Dirac quantization.

Working with Otto Frisch on space quantization produced results that apparently did not agree with the current theory; but Isidor Isaac Rabi showed that theory and experiment were in agreement if the nuclear spin of potassium was + .

However with the fairly recent development of a systematic approximation scheme for calculating observables of General relativity (for the first time) by Bianca Dittrich, based on ideas introduced by Carlo Rovelli, a viable scheme for a reduced phase space quantization of Gravity has been developed by Thomas Thiemann.