My thoughts on what the Hubble tension really is, based on George Efstathiou’s “To H0 or not to H0?“, arXiv:2103.08723.
After disappearing for a week, this week I cover three papers discussing why reducing the sound horizon is necessary but not sufficient to solve the Hubble tension, how to probe gravitational waves using astrometry, and whether unparticles might have something to do with dark energy. As of this week I’ve also decided to start including plots from the respective papers, where necessary, in my summaries, as a good plot is worth a thousand words. Enjoy!
This week I cover a proposal to confirm the possible Dirac nature of neutrinos exploiting a subtle correlation between cosmological and terrestrial measurements, how to determine the sound horizon and H0 from BAO independently of the details of recombination, and a possible interpretation of the recent detection of the stochastic gravitational wave background at nHz frequencies by NANOGrav as being due to cosmic strings. Enjoy and have a nice weekend!
