CHAPTER ONE ISAAC NEWTON AND THE APPLE On a late summer day in 1666 Isaac Newton was thinking in his garden The 23-year-old was at his boyhood home of Woolsthorpe in the east of England Newton was spending time there while his studies at the University of Cambridge were interrupted A plague had come to England in 1665 It was important to keep A n a p p l e t r e e m a y h a v e h e l p e d i n s p i r e N e w t o n s w o r k w h i c h h a d a f a r r e a c h i n g i m p a c t o n t h e s t u d y o f g r a v i t y 5
people apart so the disease could not spread So the university closed Newton went home On that summer day he was thinking about gravity He had been thinking about it for a while The term gravity came from French and Latin The French word gravité means seriousness The Latin word gravitas means weight But gravity was not used to describe a force of attraction until the 1640s People had always known objects in the air fell to Earth They did not know the reason Newton wanted to learn more about this force Legend has it that on that day in 1666 Newton was literally struck with inspiration As he sat in his garden an apple fell from a tree onto his head Suddenly the attractive force all made sense to him Although Newton was smart it took more than one bonk on the head to develop his theories But in stories Newton would later tell an apple’s fall was an important moment He never actually mentioned it hitting him on the head though 6
From the Earth to the Moon The apple helped Newton see the big picture An apple falls to Earth rather than flying off So gravity must reach the top of an apple tree Newton reasoned that if it went that high it must reach even farther than that In fact it must go all the way into space Newton believed gravity was the force keeping the moon in place He believed gravity controlled the entire universe PERSPECTIVE Newton’s Friend Remembers William Stukeley was a longtime friend of Newton’s Later in Newton’s life Stukeley went to visit the aging scientist They took a walk to Newton’s garden There Newton said how the garden reminded him of his breakthrough long ago He told me he was just in the same situation as when formerly the notion of gravitation came into his mind It was occasioned by the fall of an apple as he sat in contemplative mood Stukeley wrote Newton had studied the work of Galileo Galilei and René Descartes Galileo was an Italian 7
