Newton is most famous for his theory of gravity. But he also contributed profoundly to other areas of science and maths. Born in 1642, Isaac Newton was the son of a successful farmer in Woolsthorpe in Lincolnshire. His father died three months before Isaac was born and Newton went to live with his grandparents.
Newton at University
Isaac Newton left Woolsthorpe and entered Cambridge University in 1661. He became interested in physics, optics, mathematics and astronomy. However, when the plague epidemic reached Cambridge he moved back to Woolsthorpe. It is in this period of time that Newton supposedly sat in an orchard under and apple tree when an apple fell on his head and caused him to wonder what force causes things to always fall towards the earth. He returned to Cambridge in 1667 and continued studying and coming up with new ideas and theories. During his life he became Master of the Royal Mint, President of the Royal society, Mp for Cambridge University and, in 1705, was knighted by Queen Ann.
Newton’s laws of Motion
Newton constructed three laws of motion. His first law is that any moving object will carry on moving at a constant speed forever, or a non-moving object will remain non-moving, unless other external forces act upon it. His second law is that a force on an object is equal to the mass of the object multiplied by the acceleration of the object; this shows that the more force you apply to an object the faster it will accelerate and that if an object has more mass then it shall have more momentum, thus propelling it further. Newton’s third law is that for every action there is an equal and opposite reaction.
Newton’s work on optics
During Newton’s time most people thought of light as just being white. But Newton had observed spectral colours on the edges of prisms and lenses of telescopes when light was shone through them; other people before Newton had seen the same effect in raindrops and prisms on the edges of mirrors and thought that the raindrops or prisms added the colour to the light. He investigated this phenomenon further by shining white light through prisms. The prisms broke up the white light into a spectrum of colours. When he blocked off all the colours but one and passed it through a prism, it remained the same, so Newton came to the conclusion that white light consisted of the different colours of the spectrum but the colours of the spectrum did not consist of more basic colours.
Newton observed that all things fall towards the centre of the earth such as the apple in the orchard. From his first law of motion, he knew that some force must be causing this downwards acceleration; he called this force gravity. Newton assumed that if gravity extended to even high mountains it would probably extend to the moon. He also thought that gravity caused the moon’s orbit around the earth and that all large objects have a gravitational field. The reason he gave for the moon not crashing down to earth is the momentum, which propels the moon away while the gravity pulls it towards the earth, causing the orbit.
Alchemy is the practise of trying to turn elements such as lead into gold. Newton was a very keen alchemist. However, we know little about his alchemistical studies because he wanted to keep much of it secret as many alchemists did. His passion for alchemy did have an impact on his life. Isaac Newton had white hair by the age of 30 and was deeply depressed for a period of his life. These are both symptoms of lead and mercury poisoning. As far as anyone knows, he never succeeded in turning any other elements into gold.
Newton had noticed spectral colours on the edge of bright objects viewed through telescopes, he then designed and made a new type of telescope, a mirror telescope, which enabled bright objects to be viewed without the spectral edges. In his most famous book Principia (Philosophiae naturalis principia mathematica), he analyzes the movements of moving objects such as planets. He also explained how all the planets in the solar system are attracted to the sun and how all ‘celestial bodies’ are attracted to each other. Newton also explained other phenomena such as the effect of the sun’s gravity on the moon and the orbit of comets. Among many other things he also theorised that the earth was oblate (broader at the equator than a sphere), some scientists disagreed with him and said the earth was more egg-shaped. To settle the matter they sent expedition teams to the North Pole and Peru to take measurements which would prove who was right. The expedition teams returned a decade later with the measurements which supported Newton’s theory.
On March 20, 1727, at the age of 85 Isaac Newton died from gout and haemorrhoids. He was buried in Westminster Abbey.