COOKIES: By using this website you agree that we can place Google Analytics Cookies on your device for performance monitoring. |

University of Cambridge > Talks.cam > Mathematical Physics Seminar > Quantum geometry from the quantisation of gravitational boundary modes on a null surface

## Quantum geometry from the quantisation of gravitational boundary modes on a null surfaceAdd to your list(s) Download to your calendar using vCal - Wolfgang Wieland (Perimeter)
- Tuesday 01 May 2018, 16:00-17:00
- MR11.
If you have a question about this talk, please contact Dr Maciej Dunajski. It is arguably one of the main achievements of loop quantum gravity to have demonstrated that space itself may have an atomic structure. One of the key open problems of the theory is to reconcile the discrete spectra of geometric observables (such as area and volume) with general relativity in the continuum. In this talk, I present recent progress regarding this issue: I will show that the loop gravity discreteness of space can be understood from a conventional Fock quantisation of gravitational boundary modes on a null surface. These boundary modes are found by considering a quasi-local Hamiltonian analysis, where general relativity is treated as a Hamiltonian system in domains with inner null boundaries. The presence of such null boundaries requires then an additional boundary term in the action. Using Ashtekar’s original SL(2,C) self-dual variables, I will explain that the natural such boundary term is nothing but a kinetic term for a spinor (defining the null flag of the boundary) and a spinor-valued two-form, which are both intrinsic to the boundary. Finally, we will turn to the quantum theory and I will explain how the cross-sectional area two-form on the null surface turns into the difference of two number operators. The resulting area spectrum is discrete. Spin networks or triangulations of space do not enter the construction. This talk is part of the Mathematical Physics Seminar series. ## This talk is included in these lists:- All CMS events
- All Cavendish Laboratory Seminars
- All Talks (aka the CURE list)
- CMS Events
- Centre for Health Leadership and Enterprise
- DAMTP info aggregator
- Featured lists
- Geometry, Integrability and Twistor Theory
- HEP web page aggregator
- Interested Talks
- ME Seminar
- MR11
- Mathematical Physics Seminar
- Neurons, Fake News, DNA and your iPhone: The Mathematics of Information
- School of Physical Sciences
- Thin Film Magnetic Talks
- bld31
Note that ex-directory lists are not shown. |
## Other listsBlueSci Talks and Workshops Cambridge Cardiovascular Seminar Series Fitzwilliam Lunctime talks## Other talks“It’s like they’re speaking a different language!” Investigating an accidental resistance to school mathematics reform Making Refuge: Calais and Cambridge CGHR Practitioner Series: Andrea Coomber, JUSTICE Debtors’ schedules: a new source for understanding the economy in 18th-century England Translational Science: using biomarkers to guide clinical development in oncology |