Christmas Science 6: Newton's Birthday

In the run up to Christmas, Communicate Science offers you 20 Christmas Science Facts. We'll post one every day until the 25th December.

Newton's Birthday
One famous scientist who was born on Christmas Day is Sir Isaac Newton.

Newton was an English Physicist, astronomer, mathematician, alchemist and theologian who's book, Philosophiae Naturalis Principia Mathematica (Mathematical Principles of Natural Philosophy or more usually called 'Principia')is regarded as the most important scientific book ever written.

As well as outlining his three laws of motion, he also used the text to describe universal gravitation.
newton came in for some criticism after the publication of the book because he described an invisible force able to act over cast distances (gravity), which led to accusations that he was introducing elements of the "occult" into science.

In the second edition of the Principia, Newton used his famous phrase 'Hypotheses non fingo' (Latin for I feign/contrive no hypothesis) to rebuff these criticisms. The full text where he uses this phrase is as follows:
"I have not as yet been able to discover the reason for these properties of gravity from phenomena, and I do not feign hypotheses. For whatever is not deduced from the phenomena must be called a hypothesis; and hypotheses, whether metaphysical or physical, or based on occult qualities, or mechanical, have no place in experimental philosophy. In this philosophy particular propositions are inferred from the phenomena, and afterwards rendered general by induction."

Newton often told a story of how he was inspired to formulate his theory of gravitation when he saw an apple fall from a tree. There is no evidence to suggest that the apple hit him on the head, as depicted in many representations of the discovery since.

The location of the famous apple tree is now disputed. Woolsthorpe Manor, Newton's family home claims to have the tree in its garden, while there is a descendant of the tree in Cambridge and a local school also claims to possess the tree in its garden.