Abraham Loeb

Apr 29, 2024 | link.aps.org | Mark Hertzberg |Abraham Loeb

We analyze the possibility of global anisotropy of the Universe. We consider an altered Friedmann Lemaitre Robertson Walker metric in which there are different scale factors along the three different axes of space. We construct the corresponding altered Friedmann equations. We show that any initial anisotropies decrease into the future. At late times, the difference in Hubble parameters changes as 1/t in a radiation dominated era and as 1/t in a matter dominated era.

Sep 12, 2023 | nature.com | Morgan MacLeod |Abraham Loeb

Correction to: Nature Astronomy https://doi.org/10.1038/s41550-023-02036-3, published online 10 August 2023. In the version of this article initially published, in text and figure presentation, the described orientation of the star relative to the observer was incorrect by a sign-flip equivalent to 180°. Figs. 2, 3 and 6, Supplementary Fig. 4 and Supplementary Video 3 have been corrected to reorient the images. In the third paragraph of Discussion and in the Fig.

Aug 10, 2023 | nature.com | Morgan MacLeod |Abraham Loeb

AbstractMassive astrophysical compact halo object (MACHO) 80.7443.1718 is a high mass, eccentric binary system exhibiting the largest-known-amplitude tidally excited oscillations.

Mar 17, 2023 | link.aps.org | Mark Hertzberg |Abraham Loeb

Abstract We propose possible properties of quantum gravity in de Sitter space, and find that they relate the value of the cosmological constant to parameters of the standard model. In de Sitter space we suggest (i) that the most sharply defined observables are obtained by scattering objects from the horizon and back to the horizon and (ii) that black holes of discrete charge are well defined states in the theory.