journal club on aspects of information, quantum theory, and gravity
04 Mar 2022
When quantum fields are subject to the effects of gravitational fields, interesting effects happen. Among them, one of the most famous is Hawking’s prediction that black holes might evaporate, a process which allows the evolution of the field’s quantum state from a pure state to a mixed state. This has led a number of physicists to dispute the result claiming it goes against the principles of Quantum Mechanics, giving this prediction the name “Black Hole Information Loss Paradox” as a consequence. We shall quickly review the “paradox” and its possible “solutions” by following Unruh & Wald 2017, which concludes there is a single “conservative” approach to avoid the conclusion: the possibility that the lost information comes out near the end of the evaporation process as a final “burst”. This approach has some complications due to the need to release great amounts of information without much energy available. However, recent work with radiation due to moving mirrors suggests it might be possible if the information comes out by means of correlations of the Hawking radiation with vacuum fluctuations at late times. In most of the seminar we shall then see how Wald 2019 concludes after a deeper analysis that this approach is very unlikely to work in the black hole case, hence leading us to either accept the “paradox” as a prediction or to radically modify our knowledge of Physics to avoid it.