The title of this book differs by only two letters from A Brief History of Time that I wrote in 1988. That book stayed on the bestseller list for 237 weeks; a remarkable feat for a book that no one understood. Three years ago, I attempted to simplify my ideas in The Universe in a Nutshell, but I now gather that no one understood that, either. So, I'm now giving you a third and final chance. At the very least, you will begin to grasp the concept of circular time.
So pay attention. As Einstein points out, time may be relative, but mine's more valuable than yours. We're searching for a grand unified theory, but haven't got one, because general relativity and quantum mechanics are inconsistent with one another. So let's start with Newton, who gave us the three laws of motion, which describe how bodies react to forces, and the theory of gravity.
Newton refused to accept the lack of absolute space, even though his laws implied it, but he believed wholeheartedly in absolute time. This was a mistake, as everyone has their own four-dimensional spacetime. Einstein's theory of general relativity is based on the revolutionary suggestion that gravity is not a force like other forces, but a consequence of the the fact that spacetime is curved. Light rays, too, must follow geodesics in spacetime, as relativity predicts light will be bent by gravitational fields.
Thanks to the Doppler effect, we know that the universe is expanding as the light-shifts of stars veer towards the red end of the spectrum. If you listen carefully, you can also pick up cosmic noise, which is, in fact, the glow of microwave radiation from the early formation of the universe. So how did the universe start? All solutions to Einstein's equations point to the fact that at some time in the past the universe was squashed into a single point with zero size. At this point, which we call big bang, the density of the universe and the curvature of spacetime would have been infinite, so unfortunately all theories of cosmology break down.
Still, with me? Probably not. But never mind. I shall carry on regardless. One second after big bang, the universe would have contained mostly photons, electrons and neutrinos, and their anti-particles, together with some protons and neutrons. Colliding photons might produce an electron and a positron; if they met up they would annihilate each other, but the reverse process is not so easy. Eventually, when the temperature had fallen to allow the strong force to take effect we'd begin to see the nuclei of deuterium. From then on it was downhill through supernovae and black holes to the present day.
But how do we resolve the problem of singularity? Through supersymmetry? String theory? 10-dimensional space? These are only partial explanations. All we can say for certain is that it is possible to write five sentences that make sense on their own, but when put together in a paragraph are intelligible only to God. And me.
