About Time is about the history, the philosophy, the perception and the trouble with time, mainly from the vantage point of Einstein's time revolution. With his usual clarity and flair, Davies argues that time in the 20th century is Einstein's time, and sets out on a fascinating discussion of why Ein-stein's can't be the last word on the subject.
Before Einstein, Newton described a universe framed by Absolute Space and Absolute Time. We lived within this framework like still points on a graph, as able to move one way as another. New-tonian physical processes were "time reversible". This physics couldn't account for our lived sense of flowing and forward-moving time, but that didn't matter to Newton because we didn't appear in his physics. Time was created by God, and our sense of flowing time was an aspect of the soul, so as a physicist Newton wasn't very perplexed about either.
For Einstein, on the other hand, the intertwining of space and time were critical to the very foundations of physics. In Special Relativity, Einstein described this space/time as relative, split into the different perspectives of different observers. In General Relativity, he described space/time as curved, with a tendency to get more distorted by every mass into all sorts of baroque shapes or even to collapse altogether into a black hole. This bizarre picture seemed the last word on a murky subject, but there were three outstanding problems.
First, General Relativity seems at odds with the age of the universe. We can use its equations to map the expansion of the universe, but these calculations arrive at a different age for the whole thing than others done on the basis of radio carbon analysis of rocks. Some rocks seem to be older than the universe! Secondly, General Relativity predicts results that clash with those of quantum mechanics. Einstein hated quantum mechanics, but all the great man's venom won't explain away this conundrum.
From the human point of view, Davies' most intriguing and important criticism is that Einstein's time, "having placed the observer in a central role, makes no provision for the personal experience of flux, or the sense of past, present and future". Ein-stein's universe, like Newton's, is essentially determinist, yet our clear sense of event and of flowing time seems built into the structure of our brains, and our brains are, after all, physical things. So what kind of a physics is it, Davies wonders, that can't accord with the physics of our brains? "If we identify Einstein's theory of relativity with the modern era of physics," he summarises, "I contend that modern physics will not solve the riddle of time."
But where modern physics fails, Davies feels postmodern physics might find a solution. Chaos theory, with its depiction of open systems that operate "at the edge" of the quantum wave function, holds out more possibilities. Davies draws on physicists like Roger Penrose who think the riddle of time won't be solved until we crack the enigma of consciousness itself. Being a physicist and an extremely good writer too, Paul Davies is well placed to guide us through these conundrums.Reuse content