1375, avenue Thérèse-Lavoie-Roux
Montréal (QC) Canada

Newton’s Law of Gravity is considered valid from sub-millimetre distances up to inter-galactic space, but fails to describe important features of cosmology like the accelerating expansion component of our universe. While the most straightforward candidate for such a component is Einstein’s cosmological constant, a plausible alternative is dynamical vacuum energy, or ”quintessence”, changing over time. Hence the presence of such a field would provide energy changes to Newton’s gravity potential of the earth at short distances invisible to electromagnetic interactions.

This talk focuses on the control and understanding of a gravitationally interacting elementary quantum system using the techniques of resonance spectroscopy. It offers a new way of looking at gravitation at short distances based on quantum interference. The ultra-cold neutron reflects from a mirror in well-defined quantum states in the gravity potential of the earth allowing the application of gravity resonance spectroscopy (GRS). GRS relies on frequency measurements, which provide a spectacular sensitivity. The neutron gives access to all parameters: distance, mass, curvature, energy-momentum tensor, and torsion. We present limits on dark energy and dark matter candidates and entropic gravity  [Cr18, Iv19, Sc21].

A link between laboratory experiments on the earth and the expansion of the whole universe is provided by a description of the rainbow.  Here it is not related to the colours but to a phenomenon that was understood and explained by George Biddell Airy. It can be if weather conditions are favourable.

[Cr14]    G. Cronenberg et al., Acoustic Rabi oscillations between gravitational quantum states and impact on symmetron dark energy, Nature Physics, 14, 1022–1026 (2018).

[Iv19]     A.N Ivanov, M Wellenzohn, H Abele, Probing of violation of Lorentz invariance by ultracold neutrons in the Standard Model Extension, Physics Letters B, 797 134819, (2019).

[Sc21]    Alex J. Schimmoller, Gerard McCaul, Hartmut Abele, and Denys I. Bondar, Decoherence-free entropic gravity: Model and experimental tests, Alex J. Schimmoller et al., Phys. Rev. Research 3, 033065 (2021).

La conférence sera projetée en direct par Zoom dans la salle A-3502.1.  Le lien Zoom ne sera pas publié.

A rainbow of Canada Post, the expansion of the universe, and what these phenomena do share with ultra-cold neutrons - Hartmut Abele (TUW)