arXiv subjects

Gerard t Hooft

Publications and source records attributed to Gerard t Hooft.

24 records · Page 2Linked to original sources

arXiv2018

Time, the arrow of time, and Quantum Mechanics

It is brought forward that viable theories of the physical world that have no variable at all that can play the role of time, do not exist; some notion of time is one of the very first ingredients a candidate theory should possess. Almost by definition, time has an arrow. In contrast, time reversibility, or even the possibility to run the equations of motion backwards in time, is not at all a primary requirement. This means that the direction of the arrow of time may well be uniquely defined in the theory, even locally. We explain these statements in terms of the author's favoured deterministic cellular automaton interpretation of quantum mechanics, also to be referred to as `vector space analysis', and expand on these ideas.

quant-ph↗

arXiv2017

The firewall transformation for black holes and some of its implications

A promising strategy for better understanding space and time at the Planck scale, is outlined and further pursued. It is explained in detail, how black hole unitarity demands the existence of transformations that can remove firewalls. This must then be combined with a continuity condition on the horizon, with antipodal identification as an inevitable consequence. The antipodal identification comes with a CPT inversion. We claim to have arrived at 'new physics', but rather than string theory, our 'new physics' concerns new constraints on the topology and the boundary conditions of general coordinate transformations. The resulting theory is conceptually quite non trivial, and more analysis is needed. A strong entanglement between Hawking particles at opposite sides of the black hole is suspected, but questions remain. A few misconceptions concerning black holes, originating from older investigations, are discussed.

gr-qc↗

arXiv2016

The Quantum Black Hole as a Hydrogen Atom: Microstates Without Strings Attached

Applying an expansion in spherical harmonics, turns the black hole with its microstates into something about as transparent as the hydrogen atom was in the early days of quantum mechanics. It enables us to present a concise description of the evolution laws of these microstates, linking them to perturbative quantum field theory, in the background of the Schwarzschild metric. Three pieces of insight are obtained: One, we learn how the gravitational back reaction, whose dominant component can be calculated exactly, turns particles entering the hole, into particles leaving it, by exchanging the momentum- and position operators; two, we find out how this effect removes firewalls, both on the future and the past event horizon, and three, we discover that the presence of region II in the Penrose diagram forces a topological twist in the background metric, culminating in antipodal identification. Although a cut-off is required that effectively replaces the transverse coordinates by a lattice, the effect of such a cut-off minimizes when the spherical wave expansion is applied. This expansion then reveals exactly how antipodal identification restores unitarity - for each partial wave separately. We expect that these ideas will provide new insights in some highly non-trivial topological space-time features at the Planck scale.

gr-qc↗

arXiv2016

Nature's Book Keeping System

Establishing how one should describe and study natures fundamental degrees of freedom is a notoriously difficult problem. It is tempting to assume that the number of bits (or qubits) needed in a given Planckian 3-volume, or perhaps 2-volume, is a fixed finite number, but this ansatz does not make the problem much easier. We come not even close to solving this problem, but we propose various ingredients in phrasing the questions, possibilities and limitations that may serve as starting points.

hep-th↗

arXiv2016

Reflections on the renormalization procedure for gauge theories

Various pieces of insight were needed to formulate the rules for working with gauge theories of the electro-magnetic, weak and strong forces. First, it was needed to understand how to formulate the Feynman rules. We had to learn that there are many different ways to derive them, and it was needed to know how different formulations of the gauge constraint lead to the same final results: the calculated values of the scattering amplitudes. The rules for dealing with the infinities that had to be subtracted were a big challenge, culminating in the discovery of the Becchi-Rouet-Stora-Tyutin symmetry. Fond recollections of the numerous discussions the author had with Raymond Stora on this topic are memorised here. We end with some reflections on the mathematical status of quantum field theories, and a letter sent by Stora to the author

hep-th↗

arXiv2015

Diagonalizing the Black Hole Information Retrieval Process

The mechanism by which black holes return the absorbed information to the outside world is reconsidered, and described in terms of a set of mutually non-interacting modes. Our mechanism is based on the mostly classical gravitational back-reaction. The diagonalized formalism is particularly useful for further studies of this process. Although no use is made of string theory, our analysis appears to point towards an ensuing string-like interaction. It is shown how black hole entropy can be traced down to classical gravitational back-reaction.

gr-qc↗