Science in early civilisations
Science started with careful watching. Farmers needed to know when rivers would flood and when to sow seeds.
- Egypt: a 365-day calendar from the yearly rising of a bright star; geometry to measure fields again after floods; early medicine written on papyrus.
- Mesopotamia (Babylon): counting in 60s (we still have 60 minutes in an hour); star positions written on clay tablets.
- Indus Valley: standard weights, planned streets with drains, baked bricks of fixed size.
- China: records of eclipses and comets; later paper, the compass and printing.
These people were very practical. They knew what happens but did not always ask why.
Greek and Roman scientific thought
Greek thinkers (about 600 BCE – 200 CE) tried to explain nature with reason, not with stories of gods.
- Thales and others asked what everything is made of. Democritus said matter is made of tiny pieces called atoms.
- Aristotle sorted animals and plants into groups and wrote about motion.
- Eratosthenes measured the size of the Earth using shadows in two cities.
- Ptolemy built the geocentric (Earth-centred) model: Earth still in the middle, Sun and planets going round it.
- Hippocrates and Galen studied the body; Romans built aqueducts and roads using this knowledge.
Weak point: the Greeks rarely did experiments. They trusted thinking more than testing.
Indian mathematics and science
Indian scholars gave ideas the whole world uses today.
- Zero and place value: writing any number with only 10 digits (0–9). Brahmagupta (628 CE) wrote rules for adding and multiplying with zero.
- Aryabhata (499 CE) said the Earth spins on its axis and gave a good value of π (3.1416).
- Medicine: Sushruta described surgery; Charaka wrote about diet and disease.
- Metal work: the iron pillar in Delhi has resisted rust for about 1,600 years.
The Islamic world and medieval Europe
From about 750 to 1300 CE, Baghdad, Cairo and Córdoba were centres of learning. The House of Wisdom in Baghdad translated Greek, Persian and Indian books into Arabic.
- Al-Khwarizmi wrote about algebra; the word 'algorithm' comes from his name. He spread the Indian digits, which Europe later called 'Arabic numerals'.
- Ibn al-Haytham showed that we see because light enters the eye, and tested ideas with experiments: an early form of the scientific method.
- Ibn Sina wrote a medical book used in Europe for 500 years.
In medieval Europe, monasteries and the first universities (Bologna, Paris, Oxford) copied and taught these books. Translations into Latin in the 1100s fed the later Renaissance.
Renaissance and the Scientific Revolution
The printing press (about 1450) spread books fast. Artists like Leonardo da Vinci studied the body closely. Then came the Scientific Revolution (about 1543–1700):
- Copernicus (1543): the heliocentric (Sun-centred) model. It explained why planets sometimes seem to move backwards.
- Galileo (1610): saw moons going round Jupiter. So not everything goes round the Earth. He also tested falling bodies.
- Kepler: planets move in ellipses, not perfect circles.
- Newton (1687): three laws of motion and the law of gravity, the same rule on Earth and in the sky.
- Harvey: the heart pumps blood round the body in a circuit.
The big change was the method: observe, guess, test by experiment, measure, and share results.
Modern science: chemistry, life science and physics
- Chemical revolution: Lavoisier (1789) weighed everything and showed mass is not lost in a reaction; oxygen explained burning. Dalton (1808) gave atomic theory. Mendeleev (1869) made the periodic table.
- Light and colour: Newton split white light into colours with a prism (1660s). Later, light was found to be a wave of electric and magnetic fields.
- Life science: cells seen under the microscope (Hooke 1665); photosynthesis puzzled out step by step — van Helmont's willow tree, Priestley's mint plant that 'refreshed' air for a mouse, Ingenhousz showing light is needed; Darwin's evolution (1859); Mendel's genes; DNA structure (1953).
- Health: vaccines (Jenner 1796), germ theory (Pasteur, Koch), antibiotics (penicillin 1928).
- Physics: Planck's quantum idea (1900); Einstein's relativity (1905, 1915) changed our ideas of time, space and gravity.
Lessons from the history of science
- Science is built by many cultures, not one.
- Ideas change when better evidence arrives (Earth-centred → Sun-centred; Newton → Einstein). A big change in thinking is called a paradigm shift.
- New tools (telescope, microscope, printing) open new science.
- Science and society affect each other: discoveries change daily life, and needs of people (farming, health, trade) push science.
Key formulas and definitions
- Geocentric model: Earth at the centre (Ptolemy, about 150 CE)
- Heliocentric model: Sun at the centre (Copernicus, 1543)
- Scientific method: observe → hypothesis → experiment → analyse → conclude → share
- Paradigm shift: a big change in the basic ideas of a science
- BCE / CE: Before Common Era / Common Era (year 1 CE follows 1 BCE)
Worked examples
1. How many years passed between Aryabhata (499 CE) and Copernicus (1543 CE)?
1543 − 499 = 1044 years. Both said the Earth moves: Aryabhata that it spins, Copernicus that it goes round the Sun.
2. Eratosthenes found a 7.2° shadow angle between two cities 800 km apart. Estimate the Earth's circumference.
7.2° is 1/50 of a full circle (360 ÷ 7.2 = 50). So the circumference ≈ 50 × 800 km = 40,000 km, very close to the real value.
3. Why did Galileo's view of Jupiter's moons support Copernicus?
The moons clearly went round Jupiter, not the Earth. So the Earth is not the centre of every motion, which breaks a key belief of the geocentric model.
Common mistakes
- Thinking science began only in Europe. Egypt, Mesopotamia, India, China and the Islamic world all made key contributions.
- Saying 'Arabic numerals' were invented by Arabs. The digits and zero came from India and travelled through the Arab world.
- Believing the Greeks proved things by experiment. Most Greek science was reasoning; regular testing became normal in the Scientific Revolution.
- Thinking Einstein proved Newton 'wrong'. Newton's laws still work well for everyday speeds; relativity is needed at very high speeds and strong gravity.