# Newton's Interpretation of the Cosmos

Sir Isaac Newton published his greatest work The Mathematical Principles of Natural Philosophy, better known as the Principia, in 1687. To celebrate and commemorate the tercentenary of this event, brewers Greene King plc commissioned a sculpture by Walter Ritchie for the refurbished public house that bears Newton’s name in Cambridge.

Newton’s predictions were made with unbelievable accuracy - better than one part in a hundred million for the movement of the earth round the sun - and they remain in daily use to calculate the orbits of the moons, planets, comets and spacecraft. Newton estimated the density of the earth and the masses of the sun and planets, accounted for the flattened form of the earth, and calculated the conical motion of the earth’s axis known as the precession of the equinoxes.

He established the orbits of comets and the means by which their return could be calculated. The enormous volume of Newton’s work included the nature and behaviour of light, fluid mechanics and observational astronomy. He made his first reflecting telescope, ground his own telescope lenses and made tools to do this. A marvellous practical experimenter, he also had a mystical side, and wrote of his belief in the universality of God.

Walter Ritchie's sculpture carries five of Newton’s diagrams engraved into the perspex behind a profile of the mathematician and stretching across a representation of the heavens – suggesting Newton’s thoughts and bringing us understanding of some the mysteries of natural phenomena.

The theories represented are:

• The theory of calculus
• Oblique impact of two perfectly elastic bodies
• Newton’s organic construction of curves
• Determination of a comet’s orbit
• The reduction of the cubic