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Causality and discausality in energetic causal sets
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Orientador(es)
Resumo(s)
We investigate the causal structure of spacetime in the higher-dimensional (2d+1) Energetic Causal Sets model, a quantum gravity theory in which spacetime is fundamentally described as a discrete network of causally related events. In this model, the emergence of spacetime happens through interactions in a pre-existent energy-momentum space, and is characterized by a phase transition from an initial disordered phase, ruled by a time-irreversible dynamics, into an ordered phase, where the emergent dynamics appears to be time-reversible. More specifically, we are interested in determining whether there could be violations of causality in this model, motivated by the work of Aharonov in the Two-State-Vector Formalism of Quantum Mechanics. To accomplish this objective, we made several numerical simulations with the existing 2+1–dimensional algorithm. We found an interesting phenomenon, already identified in the 1+1–dimensional model, which is called disordered causality or discausality, when events take place in spacetime by the reverse order to which they were generated. We then proceeded to characterize this phenomenon in the two regimes identified earlier, the time-asymmetric phase and time-symmetric phase. In order to do that, we performed a step-by-step study of the dynamics of the model. We found out that the phenomenon of disordered causality happens more often in time-asymmetric phase, but with lower intensity than in the time-symmetric phase.
Descrição
Tese de Mestrado, Física e Astrofísica, 2026, Universidade de Lisboa, Faculdade de Ciências
Palavras-chave
Quantum gravity Time-symmetry Causality Causal structure of spacetime