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Cosmology (Greek, ‘study of the universe’) was, until only about 400 years ago, a matter of speculation and religious assertion. Lacking any idea of scientific method, and any technology to assist either investigation or calculation—not to mention never conceiving of the need for any of those things—the ancients invented explanations of how the universe came into being, what it was like and how it worked. God or the gods created it: if pressed, experts could give a specific date, for example by tracing generations back in time to the ‘prime mover’ or movers. Those few experts who did speculate about the heavens in what we might now call a scientific manner tended to place intellectual reasoning above the investigation and analysis of actual phenomena, and so made pictures and gave descriptions of universal phenomena and their causes which were as fanciful as any myth.
The consensus of opinion, in all societies, was that the universe was centred on the Earth—indeed, in some cases, that the Earth was the universe—and that all living beings in it, including the supernatural beings who managed it, were somehow projections of our own human selves. (Supernatural beings were bigger, existed outside mortal time, had magic powers, but were still essentially refractions of ourselves.) Above all, the universe was held to be controlled by sentient beings, on the human plan. Various forms of these ideas still persist among the adherents of some religions, either (uneasily) side by side with the discoveries of modern scientific cosmology or (triumphally) in opposition to them. Pseudoscience, too, draws heavily on such ideas: it was only 100 years ago that people were excitedly talking about irrigation canals on Mars, and there are still people who believe that such things as the Nazca lines in Peru are landing strips for extraterrestrial astronauts.
Rational cosmology began some 400 years ago with the work of Copernicus and Galileo. Their observations of the heavens showed that the facts did not fit existing theories of cosmology. Newton and others next began exploring the physical laws of Nature, studying such matters as planetary motion and the nature and properties of light. The third foundation stone of scientific cosmology came in the late 18th century, when Hutton and others demonstrated that the Earth—and by implication, the universe of which it was part—was almost inconceivably older than anyone had previously imagined. From this point on, scientific knowledge progressed at an exponential rate, and every new discovery in astronomy, biology, chemistry, geology and physics refined and clarified a factual picture of the origins, nature and functioning of the universe.
At the time of writing—and the picture still changes with each piece of new research—the consensus is that the universe began some 15,000-20,000 million years ago with a single explosion, the ‘Big Bang’. Reverberations from this can still be sensed, and debris from it is still spreading outwards, so that the universe is both constantly expanding and infinite. Some scientists predict that expansion will end when the gravitational pull of the heavenly bodies already existing balances the velocity of the debris still in motion, and stasis occurs. This possible event will be the ‘Big Crunch’, and no one can foresee what will follow it, except possibly another build-up of energy leading to another ‘Big Bang’, and so on to infinity. KMcL
Further reading John McLeish, Cosmology; , Stephen Hawking, A Brief History of Time; , Carl Sagan, Cosmos (breathlessly written, but interesting on both the science and the pseudoscience of the cosmos). |
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