Isaac Newton's apple tree

Isaac Newton's apple tree at Woolsthorpe Manor represents the inspiration behind Sir Isaac Newton's theory of gravity. While the precise details of Newton's reminiscence (reported by several witnesses to whom Newton allegedly told the story) are impossible to verify, the significance of the event lies in its explanation of Newton's scientific thinking. The apple tree in question, a member of the Flower of Kent variety, still exists today at the manor; it is a direct descendant of the tree that stood in his family's garden in 1666. It stands as a living connection to Newton's groundbreaking insights. The tree has become a cherished symbol, and its descendants and clones can be found in various locations worldwide.

The apple incident
It is known from his notebooks that Isaac Newton was grappling in the late 1660s with the idea that terrestrial gravity extends, in an inverse-square proportion, to the Moon; however, it took him two decades to develop the full-fledged theory. The question was not whether gravity existed, but whether it extended so far from Earth that it could also be the force holding the Moon to its orbit. Newton showed that if the force decreased as the inverse square of the distance, one could indeed calculate the Moon's orbital period, and get good agreement. He guessed the same force was responsible for other orbital motions, and hence named it "universal gravitation".

Newton himself often told the story that he was inspired to formulate his theory of gravitation by watching the fall of an apple from a tree. The story is believed to have passed into popular knowledge after being related by Catherine Barton, Newton's niece, to Voltaire. Voltaire then wrote in his Essay on Epic Poetry (1727), "Sir Isaac Newton walking in his gardens, had the first thought of his system of gravitation, upon seeing an apple falling from a tree."

Some have argued that the apple story is a fiction and that he did not arrive at his theory of gravity at any single moment. Acquaintances of Newton (such as William Stukeley) recorded Newton's version of the incident, though not the meritless version that the apple actually hit Newton's head. Stukeley recorded in his Memoirs of Sir Isaac Newton's Life a conversation with Newton in Kensington on 15 April 1726 (50 years after the supposed event): ""

John Conduitt, Newton's assistant at the Royal Mint and husband of Newton's niece, also described the event when he wrote about Newton's life:

"In the year 1666 he retired again from Cambridge to his mother in Lincolnshire. Whilst he was pensively meandering in a garden it came into his thought that the power of gravity (which brought an apple from a tree to the ground) was not limited to a certain distance from earth, but that this power must extend much further than was usually thought. Why not as high as the Moon said he to himself & if so, that must influence her motion & perhaps retain her in her orbit, whereupon he fell a calculating what would be the effect of that supposition."

British science writers Mary and John Gribbin assert that Newton simply made it up, because, in 1666, Newton's theory of the nature of gravity would not have encompassed it. In their view, either the elderly Newton had forgotten that he had once posited it as an explanatory analogy or (more probably) because he would not admit that Robert Hooke had given him the concept of universal gravity in his [Hooke's] 1674 Gresham lecture,  An Attempt to Prove the Motion of the Earth by Observations (published 1679), which explained that gravitation applied to "all celestial bodies".

The tree
The actual story behind Newton's apple tree can be traced back to Newton's time at Woolsthorpe Manor, his family estate in Lincolnshire, England. During his stay at the manor in 1665 or 1666, it is believed that Newton observed an apple falling from a tree and began pondering the forces that govern such motion. Dendrochronology, done by the Research Laboratory for Archaeology and the History of Art at the University of Oxford, confirms one of the trees in the orchard to be over 400 years old, having regrown from roots surviving from a tree which was blown over by a storm in 1816. In 1820, part of the blown tree was also cultivated by Lord Brownlow at Belton Park into a tree that came to be known as the Belton tree.

Other various trees are claimed to be the apple tree which Newton describes. The King's School, Grantham claims that the tree was purchased by the school, uprooted and transported to the headmaster's garden some years later. The staff of the (now) National Trust-owned Woolsthorpe Manor dispute this claim. The apple tree is a culinary apple of the Flower of Kent variety. The Flower of Kent is known for its large and flavorful, but mealy green apples, which were used for cooking and baking. The apple tree still exists today at Woolsthorpe Manor, and it is attended by gardeners, secured with a fence, and cared for by National Trust for Places of Historic Interest or Natural Beauty.

Significance
While there is debate regarding the precise details of the apple tree incident, the story has become deeply ingrained in scientific history and popular culture. The apple tree symbolizes the moment of inspiration that led Newton to develop his groundbreaking ideas. It serves as a powerful metaphor for the process of scientific discovery and the ability to perceive patterns in nature. A statue of Isaac Newton, looking at an apple at his feet, can be seen at the Oxford University Museum of Natural History. A large bronze statue, Newton, after William Blake, by Eduardo Paolozzi, dated 1995 and inspired by Blake's etching, dominates the piazza of the British Library in London. A bronze statue of Newton was erected in 1858 in the centre of Grantham where he went to school, prominently standing in front of Grantham Guildhall.

The tree was ranked number five on the TIME TOP 10 Awesome Trees on Arbor Day in 2010, and was chosen as one of the 50 Great British Trees in 2012, the year of Queen Elizabeth II's Diamond Jubilee. Part of the tree was used in the state coach for Queen Elizabeth II's diamond jubilee.

On 14 May 2010, British-born NASA astronaut Piers Sellers took a 10cm fragment of the Newton's apple tree into space as part of the celebrations for the 350th anniversary of the Royal Society, of which Newton was a former president. The tree sample, engraved with Newton's name, was originally taken from the Royal Society's archives and entrusted to Piers Sellers for his 12-day mission aboard the space shuttle Atlantis to the International Space Station (ISS). After the mission, both the tree sample and the picture was returned to the Royal Society and became part of a historical exhibition.

Seeds of the tree were sent by the European Space Agency into space to the International Space Station on the 2014-15 Principia mission with astronaut Tim Peake. As part of the "Pips in Space" research, the seeds floated in microgravity for six months before returning to Earth in 2016 to be raised into young trees. Winners of a competition to host one of the unique seedlings include the National Physical Laboratory, Jodrell Bank Observatory, and the Eden Project. In 2023, 10 saplings from the tree were auctioned to support the upkeep of Woolsthorpe Manor.

Clones
There are several genetically identical trees, or clones, of the original apple tree that have been planted around the world. Trinity College in Cambridge, Newton's alma mater, hosts a genetically identical tree, growing outside the main gate of the college below the room Newton lived in when he studied there. Woolsthorpe Manor gifted five cuttings from Newton's Apple Tree to Loughborough University, located near Newton's childhood home. These cuttings were planted at Loughborough University as part of an initiative to inspire students to think like Isaac Newton. Cambridge University Botanic Garden had a clone of Newton's Apple Tree that stood at the Brookside entrance. Unfortunately, it fell during Storm Eunice. Yet, the garden plans to plant a new clone elsewhere on the premises. National Institute of Standards and Technology (NIST), Gaithersburg campus in the United States had a clone of Newton's Apple Tree planted. But it fell over and died in June 2023 due to unknown reasons.

Grace Babson, the wife of Roger Babson, was able to pursue her collection, later amounting to over 1,000 editions of Newton materials, being the largest source in the United States. In 1995, the Babson College collection was placed on loan to MIT's Burndy Library, and in 2006, to the Huntington Library in San Marino, California, where it is available for scholarly research. Between Sir Isaac Newton Library (now known as Tomasso Hall) and the Lunder Admission Center lay descendants of the original apple trees. Grace also saved the parlour of Newton's last residence before its demolition and created a replica in Babson Park.

From 1997 to 2007, at Inter-University Centre for Astronomy and Astrophysics three endeavors were undertaken to cultivate Newton's Apple Tree brought in by Jayant Narlikar. Some of the trees managed to thrive and produce apples. However, by 2007, the last remaining tree from those attempts had perished.

Other clones can be found at Queens' College, Cambridge planted in 1948, Bushy House part of the National Physical Laboratory planted in 1953, the Royal Astronomical Society, TRIUMF planted in 1968, University of York gifted in 1976, the Massachusetts Institute of Technology (MIT) in the United States planted in 1977, Centro Atómico Bariloche planted in 1981, Koishikawa Botanical Gardens in Japan planted in 1981, York University, Toronto planted in 1999, the University of Wisconsin-Madison's Physics Department and Botanical Garden plant on 25 May 2001, University of Nebraska–Lincoln in Nebraska planted in May 2015,  Brown University in Rhode Island planted on 29 March 2018, King Edward's School in Birmingham planted in 2018, and Argentina's Parque de las Ciencias planted in 2022.

More clones can be found at the Parkes Observatory in Australia, the Observatory Science Center at Herstmonceux in East Sussex, Vanderbilt University in Tennessee, West Virginia University and College of William & Mary in Virginia, Case Western Reserve University in Ohio, Houghton University in New York, Babylonstoren in South Africa, Monash University in Melbourne, Tufts University in Massachusetts, the University of British Columbia in Canada, New York Botanical Garden in Bronx, Balseiro Institute in Rio Negro, Orange Agricultural Institute in New South Wales, Wuling Farm in Taiwan, Nankai University in Tianjin, Beihang University in Beijing, Korea Research Institute of Standards and Science (KRISS) in Daejeon, Keiwa College in Shibata, Saitama University in Saitama, Koishikawa Kōrakuen in Bunkyo, and Technical University of Applied Sciences Wildau in Brandenburg.

The East Malling Research Station in East Malling remains the primary supplier of clones of the tree since 1930, but crossing borders can be challenging and plant delivery may be delayed for inspections or possibly quarantine due to worries about invasive pests and plant diseases. Nevertheless, there appear to be two distinct apple trees, the Woolsthorpe or the Belton tree, that are now being cultivated as "Newton's apple tree", despite the fact that the numerous specimens of the tree appear to be fairly similar on the surface. Whether these are specific to the Woolsthorpe or the Belton tree is still up for debate. For example, in 2016, the tree planted at the National Research Council Canada (NRC-CNRC) in Ottawa was discovered to be a fake and not even a Flower of Kent.