Big Bang by Simon Singh

Big Bang The Most Important Discovery of All Time and Why You Need to Know About it, Simon Singh, Fourth Estate, October 2004, 544 pages, ISBN:0007152515

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Simon Singh, in the Big Bang, presents a history of cosmological investigation from Babylonian times to the present day. The Big Bang model has been a spectacular success at describing the universe we live in and, according to Simon Singh, it's the most important discovery of all time. 

Although Simon Singh's Big Bang mentions the most recent cosmological ideas, like dark matter and inflation, it focuses on the standard Big Bang model that has been accepted since the 1960s. The reader is thereby given a full account of the theory that astronomers think, almost certainly, describes the large-scale structure of our universe from the first few fractions of a second to billions of years in the future. 

Big Bang starts with a detailed look at Ancient Greek cosmology, and how it emerged from mythology. It includes a detailed account of how Eratosthenes calculated basic parameters like the circumference of the earth, diameter of the moon and the distances to the Moon and Sun. Simon Singh gives a wonderful account of how these were calculated, using his crystal-clear prose and well chosen diagrams. But he doesn't gloss over the details, he shows you exactly how to calculate these parameters yourself, using basic school geometry. Simon Singh's account reveals the full glory of Greek astronomy, which cast off explanations based on gods and myths and replaced them with scientific models.

The inaccuracies of the Ancient Greek models became embedded in Western Culture for 1300 years until Copernicus, Galileo and Newton corrected them. But they also produced a faulty model of cosmology. This model consisted of an infinite universe of stars held together by Newton's universal law of gravitation. It lasted until the twentieth century, when the Big Bang model began to usurp it. Simon Singh goes into fascinating detail about how cosmology developed throughout the period between Newton and Einstein. This is useful scene setting for his account of the Big Bang model, which was a twentieth century development.

Singh carefully relates the development of the Big Bang model during the 1920s. This includes a description of how Albert Einstein's model of cosmology provided both the spur and the halter for the development of the Big Bang theory. The spur was the work of Alexander Friedmann and others, who used Einstein's general theory of relativity to develop the Big Bang theory (in all but name). But Einstein held to theidea of a static, eternal universe, and most scientists believed him rather then the young upstarts. This involved Einstein adding a "cosmological constant" to his general relativity equation, which made it far uglier than the pure version that Friedmann used. Einstein would later say this was his greatest mistake.

The "Great Debate" of the 19th and early 20th century is given full justice by Singh. This is the debate about whether the universe contained only our galaxy, or many galaxies. The key evidence for settling this was provided by several female "computers" at Harvard who made some remarkable discoveries leading to the development of a cosmic distance scale. Simon Singh gives a full account of them and their work, and how it was used by Edwin Hubble.

Simon Singh gives a full account of Edwin Hubble, and his remarkable series of observations which, more than any other, gave us the experimental basis for modern cosmology. In one set of observations he settled the great debate by showing that many nebulae must be outside our galaxy and were, in fact, galaxies themselves. He topped this by showing that all galaxies look to be receding from a central point - the first, and best, experimental evidence in favour of  the Big Bang. Einstein recognised that the static universe was totally ruled out  by Hubble's observations and his cosmological constant was not needed. He now praised Friedmann for providing the best model of the universe. But still the Big Bang model was not generally accepted. 

The idea of a static, eternal universe was more acceptable to atheistic cosmologists than the Big Bang, which implied the notion of a creation beyond the reach of science. Also, another theory came along to explain Hubble's observations and retain the notion of an eternal universe.

In the 1940s Hermann Bondi, Thomas Gold and Fred Hoyle put forward the idea of a steady-state universe. This suggested that all galaxies were, indeed, receding away from each other, but that matter was spontaneously created throughout the universe. This creation was just enough to provide enough matter to replace the receding galaxies. Fred Hoyle, especially, pushed this theory and tried every means, technical and rhetorical, to defeat the Big Bang idea. In fact, he invented the term Big Bang during a radio interview. He attempted to dismiss the idea of a "dynamic evolving model" by using what he thought, was a disparaging term. Instead he created a term that sticks in most people's minds with, largely, positive connotations. The positive connotations depend on two pieces of experimental evidence that dealt death-blows to the steady state theory, and supported the Big Bang.

The first piece of evidence had been known for decades before Hubble's observations. Spectroscopic observations had shown that stars were composed of mostly hydrogen, with 20% helium and a small percentage of other elements. In the 1940s, George Gamow and Ralph Alpher showed that the proportions of hydrogen and helium were what you would expect from a Big Bang explosion. But, though no error was found in their work, and the steady state theory could not explain the proportions, the Big Bang was still not generally accepted. More evidence was needed.

Gamow and Alpher also showed that the Big Bang should have generated radiation that could be detected, to this day, as microwaves. Astronomers simply forgot this result until the 1960s, when other theorists developed it independently. More importantly, Arno Penzias and Robert Wilson detected it. The full story of this discovery is related by Singh, along with wonderful sketches of the dedicated researchers themselves. This was the final observation that led every unbiased astronomer to accept the Big Bang theory. 

Singh's story ends with an account of the detailed observations of the Microwave Background Radiation that have shown the "lumpiness" that theorists predicted would precede galaxy formation. This shows that observations are now about checking the predictions made within the context of the Big Bang model, which has reached the level of acceptance that Newton's contemporaries had for a Sun-centred solar system. Singh's account becomes quite sketchy after that. The account of inflation,  anthropic principle, strings, and other less-certain ideas is limited (although a good "further reading" section is given). I think Singh is right to do this, he has concentrated on showing the development of what is, probably, the most important idea of all time amongst the set of ideas that we are pretty certain about. The Big Bang theory is, almost certainly, correct and everyone deserves to know about it.

This review cannot end without mentioning the pictorial content of the book. Simon Singh obviously believes a picture is worth a thousand word, and Big Bang contains many amazing graphics. These include superb photographs of leading cosmologists, and fantastic composites like the COBE microwave background map. Also, there are many crystal clear diagrams, which make concepts like parallax and time dilation easy for anyone to understand. 

Simon Singh Big Bang, in conclusion:

• Big Bang by Simon Singh is a superb account of the most important scientific discovery of all time, and why you need to know about it - a must buy.