Reddit mentions of The Day Without Yesterday: Lemaitre, Einstein, and the Birth of Modern Cosmology

Ooh, don't forget about Georges Lemaître! He's the one generally credited with first introducing the idea of a "big bang" (and also derived what we now call Hubble's Law two years before Hubble himself did), but interestingly was also a devout priest, which is sort of unusual.

For anyone interested in any further reading on the subject, The Day Without Yesterday by John Farrell is a great, easy to read biography of Lemaître that also mentions and mixes in brief details of many of the physicists listed above (Einstein, Bohr, Heisenberg, etc). Highly recommended!