Humans have long sought explanations of the physical world. At first this was a central role of myth and religion. Nearly all cultures have origin myths, telling how the world and the first people came to be. Other myths account for all sorts of natural phenomena.
The systematic observations made by many cultures of astronomical events such as equinoxes, solstices and lunar cycles had a more practical purpose: they related to the changing seasons, vital to both hunters and farmers. A striking example is the great Neolithic ceremonial mound at Newgrange in Ireland, built around 3200 BCE , whose inner chamber is only lit by the Sun on the winter solstice. To build such a structure, which could precisely mark the passing of another year, took accurate measurement and careful observation – two of the hallmarks of what we now call science.
At around the same time, the Sumerians developed a basic lunar calendar, while by 2500 BCE the Egyptians were using a solar calendar – essential for anticipating the annual flood of the Nile. The Sumerians introduced a sexagesimal number system (using base 60, probably because 60 has 12 factors; our system uses base 10, which has only four factors, 1, 2, 5 and 10). The Babylonians followed them, and instituted the hour as a unit of time, calibrated into 60 minutes, which meant that it was evenly divisible into spans of 60, 30, 20, 15, 12, 10, 6, 5, 4, 3, 2 or 1 minute. The Babylonians were great astronomers, and by 1500 BCE were using mathematics to plot the positions of stars and planets, and to predict eclipses. The ancient Egyptians took mathematics further, and evolved some abstract geometrical principles out of the practice of land surveying.
But in the ancient world it was above all the Greeks who laid the foundations of the discipline we now call science. Their philosophers broke ground in exploring not only the nature of reality and what the good life consists of (see here ), but also the facts of the physical world. Rejecting mythological explanations, they sought to find a single underlying principle.
For Pythagoras and his followers in the 6th century BCE this principle was number. They established that the Earth is spherical, and recognized that harmonies in music are based on numerical ratios. In the following century Democritus theorized that everything consists of tiny indivisible particles he called atoms, while Empedocles proposed that matter is made up of four elements: earth, water, air and fire. The concept of the four elements was taken up in the 4th century BCE by Aristotle. He set out to observe and catalogue a vast range of natural phenomena, biological and non-biological, and from these findings to derive more general truths – the basis of the scientific method.
Around 300 BCE Euclid laid out the principles of geometry, and Archimedes later pioneered both mechanics and hydrostatics. In the 2nd century BCE Aristarchus of Samos showed that the Earth rotates on its own axis and orbits the Sun, while Eratosthenes (c . 276–194 BCE ), the Greek astronomer who became the chief librarian at Alexandria in Egypt, worked out the Earth’s circumference with remarkable accuracy. Also in Alexandria, by then part of the Roman empire, and a major centre of intellectual life, Ptolemy (Claudius Ptolemaeus, c . 90–c . 168 CE ) drew up a world gazetteer that included an estimate of geographical coordinates.
‘By convention there is colour, by convention sweetness, by convention bitterness, but in reality there are atoms and space.’
Democritus (c . 460–c . 370 BCE ), fragment 125
The Romans added relatively little to the Greek scientific heritage, and, after Rome’s fall, Greek science was largely lost in Europe. But Muslim scholars kept it alive in intellectual centres from Córdoba in the west to Delhi in the east. They also made numerous innovations. Muslim scholars adopted the Indian idea of a place value system in mathematics, including the concept of zero. This is the origin of the ‘Arabic’ numeral system we use today – much more useful for difficult calculations than the systems used by either Greeks or Romans. However, it was not until the 17th century that modern science really began, with the so-called Scientific Revolution (see here ).