The speed of the expansion of the universe is governed by the Hubble constant. Discordance tells of its troubled 100-year history, from tentative steps to measure the distances of nearby stars to orbiting telescopes peering into the far reaches of space. But recent results hint at more trouble ahead: the 'Hubble tension'. The story is not over yet.

The troubled history of the Hubble constant told in an authoritative, comprehensible, and entertaining manner

In 1927 Georges Lemaître argued that our universe is expanding, a conclusion rendered more startling by the astronomical data that backed it up, presented two years later by Edwin Hubble. The speed of this expansion is governed by Hubble's constant, and Discordance tells its troubled history.

This unpredictable and fascinating story begins with the first tentative steps to measure the distances to nearby stars and galaxies. It traces the extraordinary interplay between cosmological theory and astronomical observation which has given us the standard Big Bang theory. It was not all plain sailing, and the narrative takes us through the discovery of dark matter, the Hubble Wars of the 1970s, the invention of cosmic inflation, and other crucial scientific moments. Further satellite missions were expected to add to the clarity of our measurements. But from about 2009 onward, the results began to diverge. This is the Hubble tension and perhaps even a crisis.

Jim Baggott clearly and entertainingly guides the reader through this gripping scientific voyage--one littered with crises of confidence, astonishing discoveries, and extraordinary personalities--which still continues today.
 
Contributor Bio(s)
 
Jim Baggott, Freelance science writer

Jim Baggott is an award-winning science writer. Trained as a scientist in the Universities of Oxford and Stanford, and a former lecturer at the University of Reading, he has written popular books on science, philosophy, and history. His books include Higgs (2012), Mass (2017), for which he won the 2020 Premio Cosmos prize, Quantum Reality (2020), Quantum Space (2018), and, with the late John L. Heilbron, Quantum Drama (2024). His books have been translated into a dozen different languages, and he has won awards both for his scientific research and his science writing.