#hubble-tension

#hubble-tension

We don't merely have the Hubble tension to reckon with, or the fact that different methods yield different values for the expansion rate of the Universe today, but a puzzle over whether dark energy is truly a constant in our Universe, as most physicists have assumed since its discovery back in 1998. While "early relic" methods using CMB or baryon acoustic oscillation data favor a lower value of around 67 km/s/Mpc, "distance ladder" methods instead prefer a higher, incompatible value of around 73 km/s/Mpc.

Discordance fits into the class of conventional popular cosmology, in so far that it is an account of how our present understanding of the Universe has emerged. But it is also, with some exceptions, more historically correct than other similar books. Baggott's book is a masterpiece that combines depth with clarity and comprehensiveness with readability. It presents modern cosmology as an unfinished business, rather than as the final conclusion on what the Universe is all about.