Einstein's unfinished revolution
Published Apr 1996
The title says it all! Time is one of those endlessly fascinating topics, and I have spent much of my career researching it. What exactly is time? Why does it appear to ‘flow’? Is that an illusion? What makes the past different from the future? Where did this ‘arrow of time’ come from? Can time have a beginning and end? If so, what was there before time? We know that time is warped by gravitation and motion, but is there a limit to this? Black holes are infinite time warps, but can they also be portals to another universe, perhaps where time ‘runs backwards’? What about time travel? About Time examines all these topics and more. When I wrote this book in the early 1990s, I was disturbed by what seemed to be a conflict between the age of the universe and the ages of the oldest stars. Something wasn’t quite right. So I stuck my neck out and suggested that Einstein’s so-called cosmological constant (now called dark energy) must be at work in the universe. The idea was very unfashionable and I was able to find only one or two astronomers prepared to consider it. But a few years later it was discovered that the universe is actually accelerating in its rate of expansion, indicating it is dominated by dark energy, so it turns out I backed the right horse that time!