This history of cosmology and the successive views of the cosmos, is one of those books I would have loved to read between say 12 and 14 years-old – but I can still enjoy them very much now.
It is lots of fun and fascinating anecdotes. It explains in the clearest way the most complex astronomical and physics theories. At another level it is full of interesting epistemological observations on why one theory is believed and one is not, what is good science and bad science (eg all things being equal the simplest explanation is likely to be the right one), how the different paradigms follow each others, how one finally supersedes another one, how theory and observation complement each other, how astronomy and physics interacted in the XXth century.
Like he did with the most famous math problem in the equally fascinating Fermat’s Last Theorem, Simon Singh builds a very entertaining and well-structured crime story on the Big Bang cosmological model.
We have this ugly word in French ‘vulgarisation’ to refer to what Anglo-Saxons call ‘popular science’ although the French astronomer Camille Flammarion one of the first to write popular books on science in the late 1800s (although he may have discredited himself to the eyes of fellow scientist and therefore undermining popular science by also publishing works of science fiction and on spiritism).
Talking of popular science, the BBC has just celebrated the 50th anniversary of the astronomy programme ‘The Sky at Night’ which was first presented by the serious-but-relax Churchillian-looking astronomer Sir Patrick Moore in 1957 and still a weekly show today. It is believed it did a lot to keep popular science culture and scientific studies alive in the UK, I am afraid I cannot mention one French programme on astronomy or any other popular science subject in prime time hours. The only one I can think of, by the ridiculous brothers Bogdanoff, was mixing science and science fiction and stopped many years ago anyway.
Early astronomical discoveries are amazing by their simplicity. Armed with good sense, good reasoning, a little observation of simple facts, and the most basic trigonometry concepts, and a tool to measure angles accurately, a 11-years-old squad can re-do the line of reasoning that led ancient Greeks to calculate, with 10% accuracy:
• The circumference and diameter of the Earth (Eratosthenes and the well of Assuan)
• Then the diameter of the moon (as it crosses the shade of Earth)
• Then the distance of the moon
• Then the distance of the sun
• Then the size of the sun
How come we don't get to do that in class?
Successive paradigm on the shape of the universe
1. Earth-centred model. Fixed Earth at the centre of the universe (Ptolemy model made the official catholic paradigm)
2. Sun-centred model. Sun at the centre of the universe, Earth spinning and orbiting around the sun, the star still being a fixed background (voute céleste) (Copernicus, Kepler)
3. Milky Way. Sun being part of a group of similar stars, hence no longer the centre of a fixed celestial sphere (Herschel, 1700s).
4. Modern Universe. In 1923 US Astronomer Edwin Hubble demonstrates that nebulae are not within the Milky Way but are instead other galaxies in their own right, far beyond the Milky Way, thus ending ‘The Great Debate’.
10 fun facts about cosmology
1. Among ancient civilisation, Babylonian and Egyptians were technologists, as were Romans later. But Greeks invented Science, the contemplation of nature and the sake of knowing it understanding natural phenomena and laws. In the field of astronomy, Babylonian and Egyptian were fantastic observers in order to establish calendars and astrology predictions; but their cosmology views was stuck by religious beliefs. Aristarchus of Samos (born 310 BC) first developed a heliocentric model putting all planets in the correct order of orbiting, but it was rejected for being contradictory to common sense and cosmic myths: if Earth was not at the centre of the universe, how come objects seemed to fall towards the Earth? And if Earth was moving around the Sun, how come we are not blown away by the ‘wind’ this motion would create? Also the model of a fixed Earth in the middle of an outer fixed sphere of fixed stars was felt to better explain the absence of parallax of stars. As a result, Aristarchus and heliocentrism fell into total oblivion for two thousand years. It is now believed Copernicus had some notion of Greek heliocentrism but he did not mention it in his books, maybe by fear of referring to pre-Christian scientists.
2. The Earth-centred system was struggling to explain some astronomical observations like the apparent retrograde motion of planets. To fix that, Ptolemy (90-168 AD) came out with a complicated and bizarre cosmology involving ‘epicycles’ of planets. But it made the trick of being consistent with detailed observations. As a matter of fact, hundreds of year of investing in astronomical observations according to the Ptolemaic model made it increasingly more 'accurate' in predicting terms and too valuable to just throw away. It is one of the drivers of conservatism in science: you are better off and right living with a wrong theory that works, than throw the baby with the water. After all who cares about the real shape of the world when you spent years learning the Ptolemaic canons? Better wrong with Ptolemy than right with those Copernicians punks.
3. The middle-age world, both Christian and Islamic, picked up a few known books from Greek philosophers and scientists - mostly Aristotle and Ptolemy – but sometimes they picked the wrong ones (Ptolemy had also made a huge error in his Geography, by underestimating the circumference of the Earth – which incidentally made Columbus believe he could reach Asia by sailing West). They chose between ancient theories those that seemed roughly compatible with holy books, and made them an article of faith, prohibiting any other ones. No wonder that Copernicus’ De Revolutionibus (1543) was totally ignored – and banned - for decades.
4. Galileo was the first to use lenses and telescopes to observe the sky. Equipped with the best telescope of his time he made many observations that proved Copernicus paradigm: he discovered the moons of Jupiter, proving some objects do orbit other planets than Earth; he proved that the phases of Venus are incompatible with the Earth-centred model but look fully in line with what Copernicus predicted. The book he wrote to support the Sun-centred model – Dialogue concerning the two chief world systems – was all the more dangerous and provocative that it was written in Italian not Latin, and written as a Socratic dialogue to be understandable by anyone with good sense. Although the pope Urban VIII (Maffeo Barberini) was an youth friend of Galileo, the religious politics of the time – the competition from rising Reform – led the Catholics to be ruthless on dogma and conservatism, so Galileo had to recant in 1633 under torture threat.
5. At the beginning of the XXth century, scientists assumed a static, eternal and stable universe. After developing its General Relativity physics (1915), Einstein looked at the cosmological consequences and was horrified to see that it meant gravitational attraction would make the universe collapse. So he tweaked his own beautiful model by introducing the ‘ugly’ (to his own acknowledgment) ‘cosmological constant’ to counteract gravity and keep the universe stable.
6. The concept of a dynamic universe was first developed by theoretician physicists Russian Friedman and Belgian Lemaitre in the early 1920. Lemaitre’s theory was that modern universe evolved from the explosion of a compact, almighty, ‘primeval atom’. Although their models were based on Einstein’s general relativity physics (with the cosmological constant ditched) and compatible with it, Einstein fiercely opposed them, to the point of publicly humiliating Lemaitre – Einstein’s rejection at this point was more than enough to ruin someone’s career. However, after Hubble had observed the recession of galaxies, Einstein showed his greatness by being able to fully apologize to Lemaitre and then endorse the expanding universe theory. He made this extraordinary comment: ‘To punish me for having been such a rebel, fate made me a despot myself’.
7. Studying the spectroscopy of distant stars and galaxies, Hubble in 1929 that the wavelength of the light of most stars are getting longer (redshift), which according to the Doppler effect, means they are moving away from us. In fact the further they are, the faster they race away. It proved the universe is expanding and suggests indeed a primordial explosion (although Hubble himself never indulged into cosmology).
8. Despite this blow, British supporters of the stable universe led by Fred Hoyle came back in the 1940s with the ‘Steady State’: the universe is expanding but new matter is created in between galaxies so that there is no need of a initial explosion to explain motion and matter, and the universe remains eternal and structurally stable. As the fierce academic battle between the two paradigms hits mainstream press, Hoyle derides the expanding universe as a ‘Big Bang’ theory, thus inadvertently giving his opponents a popular label. Some cosmologists also found the big bang suspicious because it looked too much like Bible Genesis and the hand of God – besides it had been first invented by a catholic priest…
9. Meanwhile US physicists Gamow and Alpher developed the big bang paradigm, linking nucleosynthesis, astronomy and cosmology in a elegant and consistent history of the big bang, from a dense hot chaotic plasma of particles to atoms and stars. It explains the relative proportion of hydrogen and helium in modern universe from fusion in the early seconds after big bang, but fails to explain the further synthesis of carbon and heavier atoms. They also predicted that a Cosmic Microwave Background radiation (CMB) may still visible as an echo of the flash that happened 300,000 years after big bang, when electrons are finally captured by nuclei and photons are able to circulate unhindered across matter.
10. Fred Hoyle gave another hand to the big bang theory when he helped overcoming the problem of nucleosynthesis of heavy elements. However the coup de grace came Penzias and Wilson who in 1964 accidentally discovered the predicted CMB when trying to identify the cause of the noise affecting their radio-telescope. The fossil radiation had the exact wavelength predicted by Gamow was indeed coming from every direction of the sky. (Also financed by Bell Laboratories to study on natural radio waves interfering with long-distance communication, Karl Jansky had discovered cosmic radiations in the 1930s).
Simon Singh's website
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