Science et Vie — The whole universe would have originated from a Planck star

Where does our Universe come from? To this fundamental question, if any, the physicist Carlo Rovelli provides an answer based on a theory that attempts to unify Einstein’s general relativity with quantum mechanics: it would come from a Planck star, a tiny star born during a rebound … from a previous universe. Further details here. …

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phys.org: Testing Quantum Gravity with Non-Gaussianity

An international team of experts, led by the University of Nottingham, have demonstrated that only quantum and not classical gravity could be used to create a certain informatic ingredient that is needed for quantum computation. Their research “Non-Gaussianity as a signature of a quantum theory of gravity” has been published today in PRX Quantum. Please see the article …

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PhysicsWorld: Quantum gravity could be tested using ultracold atoms

Quantum gravity might soon be tested in the lab, thanks to a new analysis from our nodes in the UK, France and Hong Kong. Drawing on advances in quantum information science, the researchers have found that if gravity is fundamentally quantum rather than classical it must generate a signature known as non-Gaussianity. To look for …

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[email protected], June 6-11 2022

The Quantum Information Structure of Spacetime (QISS) interdisciplinary initiative in Quantum Information and Quantum Gravity is announcing its first large conference, to be held at Western University, in London, Ontario, Canada, the week 6-11 June 2022. The main aim of the conference will be to foster dialogue between physics and philosophy. The conference will bring together …

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Robert Oeckl
Universidad Nacional Autónoma de México

What is Quantum Theory?

Abstract: The invention of quantum theory in the 1920s represented a paradigm shift in our approach to describing the natural world. The focus on the object as a primitive shifted to the observation as a primitive. At the time, the first applications of interest came with a classical description in the language of Hamiltonian evolution, canonical variables and states. Staying close to this particular language lead to the development of the quantum formalism of Hilbert spaces, operators, Schrödinger equation and Born rule. Somewhat unfortunately, this standard formulation has come to dominate our understanding of what quantum theory is. While it was successfully employed in describing the micro-structure of matter and its relevant interactions, describing the dynamics of spacetime itself is outside of its scope. With the present talk I want to promote the idea that quantum theory is much more general than this standard formulation. I aim to clarify the essence of the paradigm shift that lies at the heart of the transition from classical to quantum theory. On this basis I then review the derivation from first principles of a more fundamental formulation of quantum theory, the positive formalism, and the recovery of the standard formulation as a special case.