Science Cosmology

Sometimes our understanding of our universe is given a huge boost by one insightful thinker. Such a boost came in the first half of the 20th century, when an obscure Belgian priest put his mind to deciphering the nature of the cosmos. The Day Without Yesterday covers the modern history of an evolving universe, and how Georges Lemaître convinced a generation of thinkers to embrace the notion of cosmic expansion and the theory that this expansion could be traced backward to the cosmic origins, a starting point for space and time that Lemaître called "the day without yesterday".

Nearly 60 years ago, Nobel Prize winners Arno Penzias and Robert Wilson stumbled across a mysterious hiss of faint radio static that was interfering with their astronomical observations. In it, they had found the key to unravelling the story of the big bang and the origin of our universe. That signal was the cosmic microwave background (CMB), the earliest light in the universe, released 379,000 years after the big bang. This is the enthralling story of the quest to understand the CMB radiation and what it can tell us of the origins of time and space.

No direct explanation is given for the origin and nature of the luminous bodies, the sun, the planets, and the stars. Because the Sumerians regarded the moon-god, who went by the names Sin and Nanna, as the son of the air-god Enlil, it does not seem unreasonable to suggest that they saw the moon as a bright, air-like body fashioned from the atmosphere. As the sun-god Utu and the Venus goddess Inanna are always referred to as children of the moon-god, these luminous bodies were probably imagined as having come from the moon after the latter had been formed from the atmosphere.