Читать книгу Big Bang - Simon Singh, Simon Singh - Страница 14

The Sun-centred model gradually became widely accepted by astronomers over the course of the next century, partly because there was more observational evidence being gathered with the aid of better telescopes, and partly because there were theoretical breakthroughs to explain the physics behind the model. Another important factor was that a generation of astronomers had passed away. Death is an essential element in the progress of science, since it takes care of conservative scientists of a previous generation reluctant to let go of an old, fallacious theory and embrace a new and accurate one. Their recalcitrance is understandable, because they had framed their entire life’s work around one model and were faced with the possibility of having to abandon it in favour of a new model. As Max Planck, one of the greatest physicists of the twentieth century, commented: ‘An important scientific innovation rarely makes its way by gradually winning over and converting its opponents: it rarely happens that Saul becomes Paul. What does happen is that its opponents gradually die out, and the growing generation is familiarised with the ideas from the beginning.’

In parallel with the acceptance of the Sun-centred view of the universe by the astronomical establishment, there was also a shift in the attitude of the Church. Theologians came to realise that they would look foolish if they continued to deny what men of learning regarded as reality. The Church softened its stance towards astronomy and many other areas of science, which gave rise to a new period of intellectual freedom. Throughout the eighteenth century, scientists would apply their skills to a wide variety of questions about the world around them, replacing supernatural myths, philosophical blunders and religious dogmas with accurate, logical, verifiable, natural explanations and answers. Scientists studied everything from the nature of light to the process of reproduction, from the constituents of matter to the mechanics of volcanoes.

However, one particular question was conspicuously ignored, because scientists agreed that it was beyond their remit, indeed inaccessible to rational endeavour of any kind. Nobody, it seemed, was keen to tackle the ultimate question of how the universe was created. Scientists restricted themselves to explaining natural phenomena, and the creation of the universe was acknowledged to be a supernatural event. Also, addressing such a question would have jeopardised the mutual respect that had developed between science and religion. Modern notions of a godless Big Bang would have seemed heretical to eighteenth-century theologians, much as the Sun-centred universe had offended the Inquisition back in the seventeenth century. In Europe, the Bible continued to be the indisputable authority on the creation of the universe, and the overwhelming majority of scholars accepted that God had created the Heavens and the Earth.

It seemed that the only issue open to discussion was when God had created the universe. Scholars trawled through the lists of Biblical begats from Genesis onwards, adding up the years between each birth, taking into account Adam, the prophets, the reigns of the kings, and so on, keeping a careful running total as they went along. There were sufficient uncertainties for the estimated date of creation to vary by up to three thousand years, depending on who was doing the reckoning. Alfonso X of Castile and León, for instance, the king responsible for the Alphonsine Tables, quoted the oldest date for creation, 6904 BC, while Johannes Kepler preferred a date at the lower end of the range, 3992 BC.

The most fastidious calculation was by James Ussher, who became the Archbishop of Armagh in 1624. He employed an agent in the Middle East to seek out the oldest known Biblical texts, to make his estimate less susceptible to errors in transcription and translation. He also put an enormous effort into anchoring the Old Testament chronology to an event in recorded history. In the end, he spotted that Nebuchadnezzar’s death was indirectly mentioned in the Second Book of Kings, so it could be dated in terms of Biblical history; the death and its date also appeared in a list of the Babylonian kings compiled by the astronomer Ptolemy, so it could be linked to the modern historical record. Consequently, after much tallying and historical research, Ussher was able to pronounce that the date of creation was Saturday 22 October, 4004 BC. To be even more precise, Ussher announced that time began at 6 p.m. on that day, based on a passage from the Book of Genesis which proclaimed: ‘And the evening and the morning were the first day.’

While this may seem an absurdly literal interpretation of the Bible, it made perfect sense in a society that judged Scripture to be the definitive authority on the great question of creation. Indeed, Bishop Ussher’s date was recognised by the Church of England in 1701, and was thereafter published in the opening margin of the King James Bible right the way through to the twentieth century. Even scientists and philosophers were happy to accept Ussher’s date well into the nineteenth century.

However, the scientific pressure to question 4004 BC as the year of creation emerged strongly when Charles Darwin published his theory of evolution by natural selection. While Darwin and his supporters found natural selection compelling, they had to admit that it was a painfully slow mechanism for evolution, wholly incompatible with Ussher’s statement that the world was just six thousand years old. Consequently, there was a coordinated effort to date the age of the Earth by scientific means, with the hope of establishing an age of millions or even billions of years.

Victorian geologists analysed the rate of sedimentary rock deposition and estimated that the Earth was at least several million years old. In 1897 Lord Kelvin used a different technique: assuming that the world was molten hot when it was formed, he worked out that it must have taken at least 20 million years to cool to its current temperature. A couple of years later, John Joly used a different assumption, namely that the oceans started off pure, and estimated how long it would have taken for the salt to have been dissolved to give the current salinity, which seemed to imply an age of roughly 100 million years. In the early years of the twentieth century, physicists showed that radioactivity could be used to date the Earth, which led to an estimate of 500 million years in 1905. Technical refinements of this technique raised the age to over a billion years in 1907. The dating game was proving to be an enormous scientific challenge, but it was becoming clear that each new measurement was making the Earth appear increasingly ancient.

As scientists witnessed this huge change in their perception of the Earth’s age, there was a parallel shift in how they viewed the universe. Before the nineteenth century, scientists generally subscribed to the catastrophist view, believing that catastrophes could explain the history of the universe. In other words, our world had been created and shaped by a series of sudden cataclysmic events, such as a massive upheaval of rock to create mountains, or the Biblical flood to sculpt the geological formations that we see today. Such catastrophes were essential for the Earth to have been shaped over the course of just a few thousand years. But by the end of the nineteenth century, after studying the Earth in more detail and in light of the latest results from dating rock samples, scientists moved towards a uniformitarian view of the world, believing in gradual and uniform change to explain the history of the universe. Uniformitarians were convinced that mountains did not appear overnight, but were uplifted at a rate of a few millimetres per year over the course of millions of years.

The growing uniformitarian movement came to the consensus that the Earth is more than a billion years old, and that the universe must therefore be even older, perhaps even infinitely old. An eternal universe seemed to strike a chord with the scientific community, because the theory had a certain elegance, simplicity and completeness. If the universe has existed for eternity, then there was no need to explain how it was created, when it was created, why it was created or Who created it. Scientists were particularly proud that they had developed a theory of the universe that no longer relied on invoking God.

Charles Lyell, the most prominent uniformitarian, stated that the start of time was ‘beyond the reach of mortal ken’. This view was reinforced by the Scottish geologist James Hutton: ‘The result therefore of our present enquiry is, that we find no vestige of a beginning, no prospect of an end.’

Uniformitarianism would have met with the approval of some of the early Greek cosmologists, such as Anaximander, who argued that planets and stars ‘are born and perish within an eternal and ageless infinity’. A few decades later, in around 500 BC, Heraclitus of Ephesus reiterated the eternal nature of the universe: ‘This cosmos, the same for all, was made by neither god nor man, but was, is and always ‘will be: an ever-living fire, kindling and extinguishing according to measure.’

So, by the start of the twentieth century, scientists were content to live in an eternal universe. This theory, however, was based on quite flimsy evidence. Although there was dating evidence that pointed towards a truly ancient universe, at least billions of years old, the idea that the universe was eternal was largely based on a leap of faith. There was simply no scientific justification for extrapolating from an Earthly age of at least billions of years to a universe that was eternal. Sure enough, an infinitely old universe constituted a coherent and consistent cosmological view, but this was nothing more than wishful thinking unless somebody could find some scientific evidence to back it up. In fact, the eternal universe model was built upon such fragile foundations that it probably deserved the title of myth rather than scientific theory. The eternal universe model of 1900 was almost as flimsy as the explanation that it was the giant blue god Wulbari who separated the sky from the land.

Eventually, cosmologists would confront this embarrassing state of affairs. Indeed, they would spend the rest of the twentieth century struggling to replace the last great myth with a respectable and rigorous scientific explanation. They strove to develop a detailed theory and sought the concrete evidence to back it up, so that they could confidently address the ultimate question: is the universe eternal, or was it created?

The battle over the history of the universe, finite or infinite, would be fought by obsessive theorists, heroic astronomers and brilliant experimenters. A rebel alliance would attempt to overthrow an implacable establishment, employing the latest in technology, from giant telescopes to space satellites. Answering the ultimate question would result in one of the greatest, most controversial, most daring adventures in the history of science.