by Prasad Ganti
Big Bang is a very comprehensive summary of the physical sciences, leading to astronomy and eventually to cosmology. This is by far the best book from Simon Singh. A well articulated story starting from the ancient Greeks to the modern Nobel prize winners in which he describes in detail the Greek’s assumptionsof a round and spinning earth, and their measurements of Earth’s circumference (Eratosthenes), relative sizes of moon and earth (Anaxagoras), and the distance to Sun (Aristarchus).
Moving to the middle ages, the story of Tyco Brahe who took observational astronomy to an entirely new level of accuracy. Kepler who was myopic and suffered multiple visions from birth interpreted Tyco’s experimental data correctly. Next comes Galileo’s experiments with pendulums, falling bodies, his observation of planets with the newly invented telescope, and his ultimate friction with the Church. Singh mentions how Galileo could uniquely maintain religious beliefs and scientific dogmas in his mind at the same time, without any conflicts.
The book continues with how Newton stood on the shoulders of giants and built on the planetary model to explain gravity. Singh writes how William Herschel used the telescope to discover the distant planets and their satellites. Herschel came up with a rough size of the Milky Way. His son John started recording celestial pictures in the newly invented medium: photography. With this technique, astronomy entered a new phase.
Singh relates how Einstein came up with his thought experiments leading to theories of relativity (special and general). For the first time I could understand that special theory of relativity applied to bodies moving at constant speeds while general relativity applied to accelerating or decelerating bodies. Time dilation and length contraction occur in fast moving bodies. Later sections relate how Einstein’s theories lead to Alexander Friedman’s prediction of an evolving Universe; how George Lemaitre’s concluded that the general theory of relativity implied a moment of creation, and hence the Big Bang. Einstein ended up denouncing both and came up with a cosmological constant, which proved to be the biggest blunder of his life. George Lemaitre, a Belgian monk, who, like Galileo, had a good balance between science and religion, letting neither interfere with the other, but at the same time being deeply involved with both.
Singh relates how John Goodricke discovered that the Cepheid stars have variable brightness because, unlike our Sun, they are not in a state of equilibrium. They go through cycles of contraction and expansion. Henrietta Leavitt found a relationship between the period of fluctuation and apparent brightness by collecting data from a group of Cepheids in the Magellanic cloud. A team of astronomers found the distance to one Cepheid. Henrietta’s relationship was used to calculate distances of other Cepheids. Edwin Hubble’s greatest contribution was to prove that Andromeda is a separate Galaxy and that the Universe is undoubtedly expanding. Hubble’s Law vindicated George Lemaitre and Alexander Friedman.
Ralph Alpher and George Gamow predicted that in the early Universe, after the Big Bang, matter existed as plasma, which cooled to 3000 degree centigrade and condensed to atoms, as the cosmic fog lifted, and the cosmic background radiation was emitted in all directions. Penzias and Wilson of AT&T discovered this red-shifted light in the microwave region. Fred Hoyle, in spite of his adherence to the losing steady state theory, made a significant contribution to the explanation of the nucleosynthesis of heavy elementsfrom dying stars.
The final chapters explain Cosmic Background Explorer’s (COBE’s) precise measurements of cosmic background radiation and subtle temperature differences in radiation of early Universe, leading to creation of stars and galaxies. This was the climactic moment for the big bang theory.
This book is a must read by anyone interested in cosmology.
Amateur Astronomers Association of Princeton 