Eureka! – a book review

Eureka!: The Birth of Science by Andrew Gregory

I recently read Eureka!: The Birth of Science by Andrew Gregory. The book deals with a topic that has long fascinated me – the birth of science. In a previous post I argued that this took place in the 12th century, the age of cathedrals. Gregory takes the view that it happened with the ancient Greeks, and sees Aristotle and Archimedes as among science’s pioneers. He gives a brief defence of this thesis, and provides a quick summary of Greek scientific thought.

Aristotle and Archimedes

I found this book rather short for the subject (177 pages, including bibliography), was disappointed at the lack of endnotes, and found some annoying errors (the Greeks did not consider the universe small, for example – Archimedes took it to be 2 light-years across). But the big unanswered question is: what went wrong? Gregory includes a list of key people at the back of the book, and if you turn that list into a bar chart, you can see that Greek science basically fell off a cliff around 200 BC.

In a brief two-page section towards the end, Gregory suggests that Christianity was somehow responsible for the decline of Greek science, but that simply makes no sense. Was it instead Roman conquest, beginning around 280 BC? Was it the growing separation of aristocratic philosophy from plebeian technology? Was it the replacement of original science by encyclopaedic systematisation (such as that of Pliny)? It would have been nice to have those questions answered.

Goodreads gives this book 3.4 stars; I was rather less enthusiastic.

Eureka!: The Birth of Science by Andrew Gregory: 2 stars


Australians know that the world is round

Following up on my earth-measuring post, people have known for more than 2,000 years that the earth is round. In 350 BC, Aristotle wrote “The evidence of the senses further corroborates this [that the earth is spherical]. How else would eclipses of the moon show segments shaped as we see them? As it is, the shapes which the moon itself each month shows are of every kind straight, gibbous, and concave-but in eclipses the outline is always curved: and, since it is the interposition of the earth that makes the eclipse, the form of this line will be caused by the form of the earth’s surface, which is therefore spherical. Again, our observations of the stars make it evident, not only that the earth is circular, but also that it is a circle of no great size. For quite a small change of position to south or north causes a manifest alteration of the horizon. There is much change, I mean, in the stars which are overhead, and the stars seen are different, as one moves northward or southward. Indeed there are some stars seen in Egypt and in the neighbourhood of Cyprus which are not seen in the northerly regions; and stars, which in the north are never beyond the range of observation, in those regions rise and set. All of which goes to show not only that the earth is circular in shape, but also that it is a sphere of no great size: for otherwise the effect of so slight a change of place would not be quickly apparent.” (On the Heavens, II, 14).

Around the year 700, Bede wrote “We call the earth a globe, not as if the shape of a sphere were expressed in the diversity of plains and mountains, but because, if all things (terrestrial) are included in the outline, the earth’s circumference will represent the figure of a perfect globe. Hence it is that the stars of the northern hemisphere appear to us, but never those of the southern; while on the other hand, the people who live on the southern part of the earth cannot see our stars, because the globe obstructs their view.” (De Natura Rerum). Australians verify his statement about stars every night.

I have commented previously on how the medieval poet Dante described time zones on a round earth:

In more recent times, we have pictures from space:

Aristotle and Bede mention the stars. Not only do the visible stars vary with latitude, but in the Northern Hemisphere they rotate around Polaris, while in the Southern Hemisphere they rotate around the South Celestial Pole, as in this photograph taken in Chile:

Sailors at sea have long known that the earth is round. From a vantage point 20 metres above sea level, one can see a complete ship 17 km away. Beyond that, the distant ship goes “hull down,” and only the upper parts of it are visible (from 34 km away, the lower 20 metres of a distant ship will be hidden). Closer to sea level, the distance is much less. This photo, taken in Spain by “Santifc,” shows the phenomenon (and similar observations can be made at some Australian beaches):

And, of course, the aircraft flight times to and from Australia can only be explained by the fact that the earth is round:

In praise of symmetry

The chief forms of beauty are order and symmetry and definiteness, and these are especially manifest in the mathematical sciences” (τοῦ δὲ καλοῦ μέγιστα εἴδη τάξις καὶ συμμετρία καὶ τὸ ὡρισμένον, ἃ μάλιστα δεικνύουσιν αἱ μαθηματικαὶ ἐπιστῆμαι) – Aristotle, Metaphysics, Book 13 (Mu), Section 3, my translation.

Symmetry, as wide or as narrow as you may define its meaning, is one idea by which man through the ages has tried to comprehend and create order, beauty and perfection” – Hermann Weyl, Symmetry, 1952, Princeton University Press, p. 5.

Regularity is successive symmetry; there is no reason, therefore, to be astonished that the forms of equilibrium are often symmetrical and regular” – Ernst Mach, The Science Of Mechanics, 1919 edition, p. 395.

Bottom left image derived from a public domain photo by Vinoo202.