NEW­TON’S AP­PLE

A MAG­GOT-IN­FESTED MYTH?

Guru Magazine - - Contents - JAMES LLOYD• PHYSICS GURU

“Eureka!” Physics Guru James Lloyd goes on a jour­ney to find out whether an ap­ple re­ally struck New­ton’s nog­gin. What he dis­cov­ers could well re­write the his­tory books

We all know the story. A young Isaac New­ton is sit­ting in his gar­den when – plonk! – an ap­ple falls onto his head. As the sci­en­tist rubs his sore scalp, an idea en­ters his mind: could the same force that brought the ap­ple plum­met­ing to the ground also ex­plain the mo­tion of the Moon and the plan­ets? In that in­stant the the­ory of grav­ity is born! At least that’s how the story goes… But did this cra­nial col­li­sion ever re­ally hap­pen? Physics Guru James Lloyd finds out. Dur­ing my un­der­grad­u­ate physics days, there was an aw­ful lot of stuff to learn. Quan­tum me­chan­ics, rel­a­tiv­ity, par­ti­cle physics – they were all sub­jects that I tried (and of­ten failed) to wrap my head around. But there was one topic that we never broached: a fa­bled event that you could say ac­tu­ally kick-started mod­ern physics. I’m talk­ing, of course, about Isaac New­ton’s fa­mous ap­ple. Did New­ton re­ally de­velop his the­ory of grav­ity af­ter see­ing a cas­cad­ing Cox? Or is the whole tale just a mag­got-in­fested myth that’s been passed down through the years? I thought it was fi­nally the time to find out. Prob­a­bly the most ob­vi­ous place to start look­ing for ev­i­dence would be Isaac New­ton’s own jour­nals and note­books. But, alas, I dis­cov­ered that New­ton never men­tioned the ap­ple in any of his writ­ings. In­stead, we must turn to a man named John Con­duitt, who wrote about the in­ci­dent some 60 years later. Con­duitt, a politi­cian by trade, was New­ton’s as­sis­tant at

the Royal Mint and the hus­band of New­ton’s beloved half-niece, Cather­ine Bar­ton. It is here that we find some re­veal­ing clues to the truth of the ap­ple event.

The case for the fruity le­gend

In his Draft ac­count of New­ton’s life at Cam­bridge, Con­duitt de­scribes a fresh-faced, 23-year-old Isaac New­ton re­turn­ing to his mother’s Lin­colnshire home in 1666 – not be­cause he missed his mum’s cook­ing, but be­cause the plague had forced the Univer­sity of Cam­bridge to shut down. There, Con­duitt wrote, “whilst he was mus­ing in a gar­den it came into his thought that the same power of grav­ity (which made an ap­ple fall from the tree to the ground) was not limited to a cer­tain dis­tance from the Earth but must ex­tend much farther than was usu­ally thought.” So Con­duitt may not de­scribe New­ton tak­ing an ap­ple to the head, or even that the sci­en­tist ac­tu­ally ob­served the fall­ing fruit, but he at least makes a pretty strong ref­er­ence to it. Around the same time, the French philoso­pher Voltaire was also help­ing to per­pet­u­ate the fruity le­gend. In An Es­say Upon the Civil Wars

of France (1727), he wrote: “Sir Isaac New­ton walk­ing in his gar­dens, had the first thought of his sys­tem of grav­i­ta­tion, upon see­ing an ap­ple fall­ing from a tree.” Voltaire prob­a­bly heard the story from Cather­ine Bar­ton, whom he de­scribed as New­ton’s “very charm­ing niece”, when he vis­ited Eng­land in the 1720s. But the strong­est ev­i­dence we find comes from an­other of Sir Isaacs’s close friends, an an­ti­quar­ian called Wil­liam Stuke­ley. In 1752, a quar­ter of a cen­tury af­ter New­ton’s death, Stuke­ley pub­lished his Mem­oirs of Sir Isaac

New­ton’s Life. Truth be told, it’s a rather drab and long-winded ac­count of the sci­en­tist’s life (though we do find out what the great sci­en­tist had for break­fast: “an in­fu­sion of or­ange peel in boil­ing wa­ter”, ap­par­ently, “with bread & but­ter”). But there on page 15, in a beau­ti­fully hand­writ­ten script, is an anec­dote that makes the mouth wa­ter more than a freshly-baked ap­ple pie: One spring day in April 1726, Stuke­ley vis­ited

an 83-year-old New­ton in Kens­ing­ton, Lon­don. Un­like to­day’s Lon­don dis­trict, Kens­ing­ton was then sit­u­ated in the coun­try­side, so the el­derly sci­en­tist had rented a house there in the hope that the fresh air would im­prove his de­clin­ing health. The two men spent the day to­gether, and their con­ver­sa­tions car­ried on into the evening. “Af­ter din­ner, the weather be­ing warm, we went into the gar­den, and drank thea [ sic] un­der the shade of some ap­ple trees…,” re­called Stuke­ley. “Amidst other dis­course, he told me, he was just in the same sit­u­a­tion as when for­merly, the no­tion of grav­i­ta­tion came into his mind. ‘ Why should that ap­ple al­ways de­scend per­pen­dic­u­larly to the ground,’ thought he to him­self, oc­ca­sion’d by the fall of an ap­ple, as he sat in a con­tem­pla­tive mood. ‘ Why should it not go side­ways or up­wards but con­stantly to the Earth’s cen­tre?’” So, while drink­ing this cup of ‘thea’ in the dusky evening light, Sir Isaac ac­tu­ally re­counted the fall­ing ap­ple story to his friend Stuke­ley. The fa­mous ap­ple! From the horse’s mouth!

A mouldy tale

But can we re­ally trust Stuke­ley? Af­ter all, he was a very good friend of New­ton and may have been tempted to mythol­o­gise the sci­en­tist. As Scott Berkun, author of The Myths of In­no­va­tion,

writes: “bi­og­ra­phers, cer­tainly in 1720, are not ob­jec­tive re­porters run­ning around check­ing facts. They are of­ten fans of their sub­jects, as Stuke­ley was of New­ton.” And why would New­ton have waited 60 years be­fore shar­ing the story with some­one? One ex­pla­na­tion may be that he saw a fall­ing ap­ple in his youth and grad­u­ally embellished the story over time. It’s easy to see why it’d be such an at­trac­tive tale: a sim­ple vis­ual metaphor for his “Eureka!” mo­ment; a hu­mor­ous way to ex­plain how grav­ity works. And then there’s the im­por­tant fact that New­ton was deeply in­ter­ested in re­li­gion, so the nod to the Gar­den of Eden’s for­bid­den fruit might have ap­pealed to him. One thing we can be sure of is that the ap­ple never struck New­ton on the head. That de­tail was added by a later writer, Isaac D’Is­raeli, who ev­i­dently had a pen­chant for slap­stick com­edy. But that hasn’t stopped the story from en­ter­ing pop­u­lar con­scious­ness. Woolsthorpe Manor, Isaac New­ton’s birth­place and the home he re­turned to in 1666, has since be­come some­thing of a pil­grim­age site. In the house’s gar­den, vis­i­ble from New­ton’s old bed­room win­dow, is said to be the very ap­ple tree that the young sci­en­tist sat un­der nearly 350 years ago.

As for the ap­ple it­self, the tree at Woolsthorpe Manor pro­duces a rare va­ri­ety of cook­ing ap­ple known as ‘Flower of Kent’, which has been de­scribed as mealy, sharp, and quite fla­vor­less. So if New­ton re­ally did see one fall to the ground, he prob­a­bly didn’t en­joy eat­ing it. Ul­ti­mately, we’ll per­haps never know the full truth be­hind New­ton’s ap­ple. Maybe we should trust those anec­dotes pro­vided by his friends. Maybe, in the grand scheme of things, it doesn’t re­ally mat­ter. Af­ter all, New­ton went on to de­velop his the­ory of grav­ity in the end, ap­ple or not. One thing’s for sure though – we should be glad that it was New­ton sit­ting un­der that tree. Any­one else would have re­quired a whole barrel full of fruit…

BE­LOW: Woolsthorpe

Manor.

ABOVE: This ap­ple tree at Woolsthorpe Manor grew up from the fallen trunk of an­other ap­ple tree that ex­isted in New­ton’s day.

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