About Time by Paul Davies: Einstein’s Unfinished Revolution, from Quantum Tunnelling to the Big Bang
What is time, and did it really begin with the Big Bang? In About Time, the physicist Paul Davies follows the question from Einstein’s relativity to quantum mechanics and modern cosmology. The reviewer’s reading notes, published in Spanish under the title Sobre el tiempo, show how much ground it covers.
Author: Paul Davies (born 1946)
Title: About Time: Einstein’s Unfinished Revolution (1995)
Format: English paperback (Penguin Science), 320 pages
Scope: Physics and cosmology of time
Amazon: www.amazon.es/dp/0140174613 (ASIN 0140174613)
Einstein’s Shadow
The book opens with Einstein, and the reviewer notes two of his lines: "Science without religion is lame, religion without science is blind" and "Imagination is more important than knowledge." Davies also takes aim at scientific jargon, the "esoteric code" that keeps the club exclusive and dazzles non-scientists with impenetrable mathematics. Einstein, he suggests, had one answer in his hands when he first formulated general relativity: the cosmological constant, the "criminal" Eddington said he knew existed without knowing what it looked like.
Quantum Time
"If quantum mechanics is correct, then the world is crazy," Einstein complained. Davies explains quantum tunnelling, in which some particles in a stream that meets a barrier bounce back while others materialise on the far side and carry on, and asks how long an electron takes to make such a jump. He also describes the quantum Zeno effect, the physics of "a watched kettle never boils", and the idea that the quantum state of the universe is one of the special states that allow time to emerge, blurred and ill-defined at first, from the primordial mess after the Big Bang.
Redshift, Rings and Ripples
A large part of the book examines how we measure the universe: Hubble’s law and its validity at the edge of the visible universe; Einstein rings, where a massive object bends light into a ring; Stephan’s Quintet, a tight group of galaxies that seem to disturb one another; and Halton Arp’s "discordant redshifts", his claim that redshift is not always a measure of distance, which challenged the Big Bang model. Davies also covers the COBE "ripples", the tiny hot and cold spots in the cosmic background radiation hailed as "wrinkles in time", along with dark matter, inflation and the rate at which the expansion of the universe is slowing.
Paul Davies
Paul Davies, born in London in 1946, is a theoretical physicist and cosmologist who has worked in Britain, Australia and the United States, where he founded a research centre at Arizona State University devoted to fundamental questions in science. He is also one of the most prolific popular-science writers of his generation, with books such as God and the New Physics, The Mind of God and The Last Three Minutes. In 1995 he received the Templeton Prize for his work on science and religion.
A Puzzle of the 1990s
When the book appeared, cosmology faced an embarrassing problem: some estimates of the expansion rate of the universe implied that it was younger than its oldest stars. Davies discusses that "age crisis" in detail. A few years later, in 1998, astronomers discovered that the expansion of the universe is accelerating, driven by what is now called dark energy, a finding that helped resolve the contradiction and won the Nobel Prize in 2011. Reading the book with that knowledge makes it a fascinating snapshot of science in the making.
Who Will Enjoy It
Readers who enjoyed Stephen Hawking’s A Brief History of Time and want a deeper, more focused exploration of time itself.
Why Read It
The reviewer’s detailed notes, running from Milne’s two time scales to the cosmic distance ladder, suggest a book to read slowly, pencil in hand. It is demanding in places but never hides behind the jargon it criticises, and it remains one of the best popular accounts of what physics says about time.
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