Virtual Seminars

After ten years in science, wandering between quantum gravity and quantum foundations, I have entered l’Institut National du Service Public (ex-ENA) to pursue a career as top executive in the French administration. In this unusual talk, I will offer my personal take on the following questions: – Is there a life after academia? – What …

Pierre Martin-Dussaud
  Institut National du Service Public

Can French Administration be more sexy than Quantum Gravity? Read More »

Modern physics has taught us that space and time are described by different “theories of geometry” in different regimes, from Galilean spacetime in Newtonian mechanics to semi-Riemannian manifolds in general relativity. In a very similar, but less well-known sense, classical probability theory and quantum theory (QT) are special cases in a large landscape of “theories …

Markus Müller
  IQOQI Vienna

How spacetime constrains the structure of quantum theory Read More »

Quantum mechanics is a theory of wave functions in Hilbert space. Many features that we generally take for granted when we use quantum mechanics — classical spacetime, locality, the system/environment split, collapse/branching, preferred observables, the Born rule for probabilities — should in principle be derivable from the basic ingredients of the quantum state and the …

Sean Carroll
  Johns Hopkins University

Extracting the Universe from the Wave Function Read More »

In the standard Fock representation, the 1-photon Hilbert space is spanned by positive frequency, source-free solutions of Maxwell’s equations. The quantum information they carry corresponds precisely to the two radiative modes of the Maxwell fields.  However, this Fock representation is inadequate in a number of physical situations involving sources, and one then has to use appropriate non-Fock representations. …

Abhay Ashtekar
Pennsylvania State University

The many faces of photons Read More »

It has been occasionally remarked, but insufficiently appreciated, that there are two distinct sorts of endeavour that have gone by the name of “thermodynamics”. The first, which is in line with how the founders of the subject thought of it, is a theory about how agents with limited means of manipulation and limited access to …

Wayne Myrvold
Western University

A Tale of Two Sciences, Both Called “Thermodynamics” Read More »

John Wheeler was the inventor of quantum gravity – not as a formal program for uniting general relativity and quantum mechanics, but as the potential key to a theory of everything. In this talk, I will show how he first imbued quantum gravity with this new role in the 1950s and then how (and why) …

Alexander Blum
  Max Planck Institute for the History of Science

John Wheeler and Quantum Gravity Read More »

I intend to discuss the implications of the principle of locality for interference in quantum field theory. As an example, I will consider the interaction of two charges via a mediating quantum field and the resulting interference pattern, in the Lorenz gauge. Using the Heisenberg picture, I will claim that detecting relative phases or entanglement between …

Vlatko Vedral
University of Oxford

Interference in quantum field theory: detecting ghosts with phases Read More »

Testing the quantum character of weak forces such as gravity requires both exquisite experimental control of technology and careful design by theory of the experiment set-up. At the same time, the interpretation of experiments that probe the interface between quantum physics and gravity also mandates that we examine carefully all the assumptions, however innocuous, that …

Martin Plenio
  Ulm University

Testing of Quantum Aspects of Gravity at Low Energies: Discussion of Experiment Aspects and Possible Loopholes Read More »

It is well known that, even the simplest states within the simplest field theories, are highly entangled. The main support for this fact comes from calculations of entanglement entropy between a region of space and its complement. I find two uncomfortable facts in the calculation of such entropy: (i) The result is actually infinite, and …

Ivan Agullo
Louisiana State University

Entanglement in quantum field theory Read More »