Spacetime singularities are often held to be pathologies which need to be resolved, and researchers working on the foundations of physics often pin their hopes on the elusive quantum theory of gravity to offer a way to resolve singularities. What is less agreed upon is what such a resolution would amount to: what criteria would a theory of quantum gravity have to fulfill to resolve spacetime singularities? In this paper, I critically analyze one criterion proposed within canonical quantum cosmology for the avoidance of the big bang singularity, to draw philosophical lessons about how to interpret such criteria. The criterion, when applied to symmetry-reduced cosmological models, claims to avoid the big bang by making the wavefunction of the universe vanish 'at' the singularity. I ask whether it works as intended, and even if it does, whether avoiding the singularity is the same as resolving the singularity.
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http://dx.doi.org/10.1016/j.shpsa.2022.09.015 | DOI Listing |
Ann Sci
January 2025
Niels Bohr Institute, Copenhagen University, Copenhagen, Denmark.
So-called antimatter in the form of elementary particles such as positive electrons (antielectrons alias positrons) and negative protons (antiprotons) has for long been investigated by physicists. However, atoms or molecules of this exotic kind are conspicuously absent from nature. Since antimatter is believed to be symmetric with ordinary matter, the flagrant asymmetry constitutes a problem that still worries physicists and cosmologists.
View Article and Find Full Text PDFMicroorganisms
December 2024
Department of Radiology, Hallym University Sacred Heart Hospital, Hallym University College of Medicine, Anyang 14068, Republic of Korea.
Peritonsillar abscesses and deep neck infection are potentially serious infections among patients with chronic kidney disease (CKD), posing risks for severe complications and drawing significant public health concern. This nationwide, population-based longitudinal study (2002-2019) assessed the extended relationship between chronic kidney disease (CKD) and the likelihood of peritonsillar abscess and deep neck infection in a Korean cohort. Using a 1:4 propensity score overlap-weighted matching, we included 16,879 individuals with CKD and 67,516 comparable controls, accounting for demographic variables and comorbidities to ensure balanced group comparisons.
View Article and Find Full Text PDFSci Rep
December 2024
National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, 32310, USA.
Plastic damage of REBCO (REBaCuO, where RE=rare earth) coated conductors by screening current stress (SCS) is a significant concern for ultra-high-field superconducting magnets. Indeed, the third Little Big Coil (LBC3), a REBCO magnet that generated a record, high field of 45.5 T, showed wavy plastic damage produced by excess SCS in all pancakes except two made with single-slit conductors having their slit edges pointing inward towards the magnet center.
View Article and Find Full Text PDFBiomimetics (Basel)
December 2024
Institute of New Frontier Research, Hallym University College of Medicine, Chuncheon 24253, Republic of Korea.
Objective: We previously developed artificial intelligence (AI) diagnosis algorithms for predicting the six classes of stomach lesions. However, this required significant computational resources. The incorporation of AI into medical devices has evolved from centralized models to decentralized edge computing devices.
View Article and Find Full Text PDFNature
December 2024
NRC Herzberg, Victoria British Columbia, Canada.
Recent observations have found a large number of supermassive black holes already in place in the first few hundred million years after the Big Bang, many of which seem to be overmassive relative to their host galaxy stellar mass when compared with local relation. Several different models have been proposed to explain these findings, ranging from heavy seeds to light seeds experiencing bursts of high accretion rate. Yet, current datasets are unable to differentiate between these various scenarios.
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