Month: September 2022

ENTROPY LAW. “The discovery of Hawking radiation showed that a black hole radiates like a black body and has a thermodynamic (Bekenstein-Hawking) entropy proportional to the area of the black hole horizon.” https://lnkd.in/dUKnus8 View in LinkedIn

THE INFORMATION PROBLEM. “For a sub-system of a larger quantum system, its thermodynamic entropy is usually identified with its number of quantum degrees of freedom, i.e., the logarithm of the number of its quantum states, and corresponds to its maximum possible von Neumann entropy as part of a larger system. The assumption, called the "central dogma" that this is true for black holes is what leads to the black hole information problem.” https://lnkd.in/dUKnus8 View in LinkedIn

DESPISING HYPOTHESES. “Hitherto I have not been able to discover the cause of those properties of gravity from phenomena, and I frame no hypotheses, for whatever is not deduced from the phenomena is to be called an hypothesis; and hypotheses, whether metaphysical or physical, whether of occult qualities or mechanical, have no place in experimental philosophy. In this philosophy particular propositions are inferred from the phenomena, and afterwards rendered general by induction.” https://lnkd.in/dD8RdgD View in LinkedIn

Two pigeon embryo siblings met a harsh ending on the hot summer pavement after falling from their nest. View in LinkedIn

INFO PARADOX. “Somehow, the quantum information apparently carried into the black hole by Hawking partners must reappear outside the black hole horizon, even though this would seem to require acausal propagation of quantum information.” https://lnkd.in/dUKnus8 View in LinkedIn

INFORMATION. “Could complete quantum information be stored on the black hole horizon, at least for external observers? Could a black hole horizon never form, instead becoming a fuzzball or gravastar that has no event horizon and no trapped surfaces? Does entanglement between late Hawking modes and early Hawking modes apparently required to restore unitarity imply a singular "firewall" at the horizon?” https://lnkd.in/dUKnus8 View in LinkedIn

AN EXCEPTION? “All of these alternatives contradict semi-classical expectations for large black holes. Why should an black hole horizon behave differently than an ordinary null hypersurface in Minkowski spacetime?” https://lnkd.in/dUKnus8 View in LinkedIn

WORMHOLES. “Later in the evaporation process the Hawking partners must correspond to different degrees of freedom than the earlier Hawking partners, and given the finite Hilbert space the Hawking modes with which they are entangled must then be entangled with early Hawking modes, leading to a pure external state when the black hole disappears. This is justified by a very complicated quantum path integral involving "replica wormholes".” https://lnkd.in/dUKnus8 View in LinkedIn

NEW PARADIGM NEEDED. “In any BH to WH scenario of the type considered in this paper and Paper I the central dogma is clearly false.” (BH = black hole; WH = white hole). https://lnkd.in/dUKnus8 View in LinkedIn

A CLUE. “The entanglement entropy of the black hole is not at all constrained by the Bekenstein-Hawking entropy at late stages of black hole evaporation.” https://lnkd.in/dUKnus8 View in LinkedIn