2026 CAP Congress / Congrès de l'ACP 2026

Session

(DTP) T3-2 | (DPT)

T3-2

23 Jun 2026, 16:15

U. Ottawa - Learning Crossroads (CRX) Building

888. The problem of time in quantum gravity: a cosmological case

Prof. Saeed Rastgoo (University of Alberta)

23/06/2026, 16:15

Theoretical Physics / Physique théorique (DTP-DPT)

Oral (Non-Student) / Orale (non-étudiant(e))

The problem of time is one of the most profound issues in fundamental physics. It states that all observable are frozen in coordinate time. However, there are several solutions proposed to this issue. I will briefly review the problem, and then present a solution based on the Montevideo Interpretation, a relational approach combined with the so-called evolving constants of motion,in the...

852. Causal Structure and Topology Change in Lorentzian Simplicial Gravity

Seth Asante (University of New Brunswick)

23/06/2026, 16:30

Theoretical Physics / Physique théorique (DTP-DPT)

Oral (Non-Student) / Orale (non-étudiant(e))

Abstract:
The gravitational path integral requires summing over geometries, yet it remains unclear which configurations should be included and which principles should constrain this sum. In particular, the role of causal structure and topology change remains subtle, especially in Lorentzian quantum gravity where amplitudes are intrinsically complex and highly constrained.

In this talk,...

767. Anomaly in canonical semiclassical gravity

Irfan Javed (University of New Brunswick)

23/06/2026, 16:45

Theoretical Physics / Physique théorique (DTP-DPT)

Oral Competition (Graduate Student) / Compétition orale (Étudiant(e) du 2e ou 3e cycle)

We show that the canonical formulation of the semiclassical Einstein equation, where the matter terms in the constraints are replaced by expectation values of the corresponding operators in quantum states, is inconsistent due to the nonclosure of the resulting constraint algebra.

941. Superposed quantum evolutions across chaotic and regular regimes

Amit Anand

23/06/2026, 17:00

Theoretical Physics / Physique théorique (DTP-DPT)

Oral Competition (Graduate Student) / Compétition orale (Étudiant(e) du 2e ou 3e cycle)

While the superposition of quantum evolutions is known to produce interference effects, the interference between evolutions with regular and chaotic classical limits remains largely unexplored. Here, we use a Mach–Zehnder interferometer to investigate the superposition of two quantum evolutions, implemented via post-selection, and to compare it with the corresponding classical mixture. The...

920. Local phase space representation of quantum fields

Karl-Peter Marzlin

23/06/2026, 17:15

Theoretical Physics / Physique théorique (DTP-DPT)

Oral (Non-Student) / Orale (non-étudiant(e))

We derive a phase-space representation of non-relativistic and relativistic quantum fields by expanding the field operator in terms of a set of localized wave packets. The corresponding probability amplitude depends on mean position and momentum of each wave packet, which serve as phase space coordinates. The dynamical equation of the probability amplitude takes the form of a classical Vlasov...