The standard quantum mechanics does not forbid time-travel. However, some alternative formulations (based on the so called “rigged Hilbert space”) include irreversibility as a fundamental principle: a quantum particle that decays cannot travel back in time.
There are not direct evidences of the irreversibility of decay processes, but the new quantum mechanics predicts that the decay rates are quantized.
If one observes the quantization of the decay rates, one can claim to have provided experimental support to the irreversible formulation of quantum mechanics.
In simple terms, one can claim that time-travel is not possible at the quantum level (…and also at the classical level).
Silvia Gentilini, Maria Chiara Braidotti, Giulia Marcucci, Eugenio Del Re, and Claudio Conti simulated in the laboratory one of the simplest models of the irreversible quantum mechanics, that follows an original proposal of Glauber. A laser beam emulates a quantum particle in a reversed harmonic oscillator, as a result the first experimental evidence of the quantization of decay time is reported in a paper published in Scientific Reports.
(reprint from the former complexlight.org website)
The fact that black holes are solitons is not very well known. Abdus Salam and others outlined this issue several years ago. Stephen Hawking predicted that Black Holes evaporate, and this is a quantum effect on classical gravity governed by the highly nonlinear Einstein-Hilbert equations.
Leone Villari, Ewan Wright, Fabio Biancalana and Claudio Conti report on the possibility that all types of classical solitons may evaporate in the quantum regime. A paper in the arXiv contains the theory on the exact quantization of the nonlinear Schroedinger equation: solitons emit a blackbody radiation spectrum at a temperature given by the same formula of Hawking!
This result is intriguing. On one hand, because it represents the first theoretical prediction of the Hawking radiation in a fully nonlinear quantum field theory. The standard Hawking theory relies on the quantization of a linear field in a curved background. The theory may hence provide insights for a true quantum gravity based on the complete quantization of the Einstein-Hilbert equations.
On the other hand, the result is also important because the Hawking radiation from a quantum soliton may furnish a novel highly tunable quantum source with many possible applications.
In recent years, researchers question about the limits of the uncertainty relation.
Hints from quantum gravity theories suggest that the Heisenberg principle should be generalized.
Some considered implications in high energy physics, others have considered the mechanical motion of massive objects to look for possible tests of these supposed limits to the most important paradigm of quantum mechanics.
In a project funded by the John Templeton Foundation, we consider the case of the photon, and study the possible way a generalized uncertainty principle may play a role in modern photonics, nonlinear and quantum optics.
The project started in 2015 and will finish in 2017, stay tuned.
The Quest for Quantum Gravity in Optics
The Math of Irreversibility
Black holes evaporate, Black are solitons, solitons evaporate !
In a paper in arXiv Giulia Marcucci and Claudio Conti report on the mathematical structures of the so-called Time Asymmetric Quantum Mechanics. This theory predicts that time-travel is not possible and explain evidences as the Big Bang or the decay of unstable particles. The authors argue that possible shaping of the initial state of a system may furnish a road to validate these fascinating developments in quantum mechanics. The work also follows the experimental evidence of the quantization of the decays rates.
The picture above shows a pictorial representation of the Gelfand triplet, the phase space of the Time Asymmetric Quantum Mechanics