Tag Archives: physics

Newton’s Apple: Fact or Fiction?

6 Jun

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 motions 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?

Is Newton's apple just a maggot-infested myth? (credit: dreamiurg)

Is Newton’s apple just a maggot-infested myth? (credit: dreamiurg)

Newton’s famous apple incident is an event that – if true – pretty much kick-started modern science. By inspiring Newton’s theory of gravity, it laid the foundations upon which countless great minds have built their ideas. But did Newton really develop his theory after seeing a cascading apple? Or is the whole tale just a maggotinfested myth that’s been passed down through the years? I decided to find out.

The case for the fruity legend

Probably the most obvious place to look for evidence would be Isaac Newton’s own journals and notebooks. But alas, 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.

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 Cambridge University 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, nor even that the scientist actually observed the falling fruit, but he at least makes a pretty strong reference to it.

Woolsthorpe Manor - Newton's Lincolnshire birthplace (credit: David Ireland)

Woolsthorpe Manor – Newton’s Lincolnshire birthplace (credit: David Ireland)

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 for Newton’s apple 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” functional yet tangy). But there on page 15, in a beautifully handwritten script, is an anecdote that waters the mouth more than a freshly-baked apple pie…

William Stukeley's handwritten apple anecdote

William Stukeley’s handwritten apple anecdote

One spring day in April 1726, Stukeley visited an 83-year-old Newton in Kensington, London – at that time situated in the countryside. The two men spent the day together, profiting from the fresh air and chatting 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, an elderly 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 fact that Newton was deeply interested in religion, so the nod to the Garden of Eden’s forbidden fruit might have appealed to him.

But even if Newton did observe a tumbling apple in 1666, it’s highly unlikely that he developed his theory of gravity right there on the spot. At some point, though – and this is what fits in nicely with the apple story – he came to realise that the same force which governs the acceleration of objects towards the ground also reaches far out into space. It wasn’t until 1687, some 20 years after the alleged apple incident, that Newton published his universal law of gravitation, showing that the orbits of the planets around the Sun – and the Moon around the Earth – could be explained by the bodies’ mutual gravitational attraction.

The Moon's orbit - beautifully explained by Newton's law of universal gravitation (credit: wvs)

The Moon’s orbit – beautifully explained by Newton’s law of universal gravitation (credit: wvs)

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 for starry-eyed physicists. 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.

The apple tree under which Newton is said to have sat. The tree was reportedly re-rooted after a storm toppled it in 1816 (credit: dexter_mixwith)

As for the apple itself, the tree at Woolsthorpe Manor produces a rare variety of green cooking apple known as ‘Flower of Kent’, which has been described as mealy, sharp, and quite flavourless. So if Newton really did see one fall to the ground, he probably didn’t enjoy eating it.

Ultimately, perhaps we’ll 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…

This blog post is based on an article published in the June/July 2013 edition of Guru magazine… download the magazine for free here!

Recent writings…

9 Feb

Some of the recent writing shenanigans that I’ve been getting up to…

  • I’ve written an article for the ever-brilliant (and now Wellcome Trust-funded) Guru magazine about the science of dancing. Guru is well worth a look if you haven’t checked it out yet… plenty of thought-provoking articles to get your teeth into (and it’s free to download as well). The February/March issue is out now.

Science of dancing

  • The March 2013 issue of BBC Focus magazine features my interview with Silas Beane, a theoretical physicist who thinks he’s found a way to test the idea that we’re all living inside a Matrix-style simulation. Mind-bending stuff…

Living in a simulation?

  • I’ve also been finding time to write a few short pieces of fiction, including “Little Death” (the story of a trainee Grim Reaper), a poem about history called “Hitler was a Milkmaid” and some other bits and bobs.

Operation Doorstep or: How to Nuke a Family of Mannequins

29 Aug

For me, there’s something profoundly creepy about mannequins. It might be those soulless, I’m-going-to-kill-you-in-your-sleep eyes. Or those smiling, impossibly unwrinkled faces. Or it might just be a side effect of my early childhood visit to a wax museum on the Isle of Wight, which still haunts me this very day. (It was like someone had purposefully set out to create the weirdest museum on Earth, complete with a terrifying Chamber of Horrors, several inexplicably naked female figures, and a truly nightmarish taxidermy collection of winged monkeys, two-headed lambs, and cats dressed as Victorians – I kid you not.)

But I digress. Mannequins. What could be worse than a mannequin? Well a whole blimmin’ community of them for starters. And on 17 March 1953, several families of these glassy-eyed dummies gathered together deep within the Nevada desert for a rather unusual occasion. They were about to experience the full force of a nuclear attack.

A mannequin mother and children await the nuclear attack

This strange mannequin community was the brainchild of the US Federal Civil Defense Administration (FCDA). Close by was a 15-kiloton nuclear weapon (‘Annie’) that was about to be detonated – the latest in a series of tests carried out by the US Atomic Energy Commission. The location – the Nevada Test Site – had been used for nuclear testing many times before, but this test was different. ‘Operation Doorstep’ was its official name, and it was designed to show what would happen if a nuclear bomb hit a typical American suburb.

About 1km from the explosion, the FCDA built a simple wooden-frame house with two storeys and a basement, kitting it out with government surplus furniture. An identical house was built further away, at a distance of nearly 2.5km from ground zero, and mannequins were placed in the rooms and basements of both houses. Several bomb shelters were also scattered around the site, as well as a selection of vehicles of various shapes and sizes.

Mannequins wait in one of the basement shelters

“This car will go thru the atomic blast”

More than 600 people watched the test, which exploded with around the same energy as the bomb that had been dropped on Hiroshima 8 years earlier.

The ‘Annie’ nuclear explosion (top) is watched by bedazzled onlookers (bottom)

Unsurprisingly, the house nearest the explosion collapsed in dramatic fashion: the ground floor was completely demolished, the first floor collapsed, and the roof was ripped off. The house further away, on the other hand, stood firm, though its doors, windows and interior were badly damaged. The best protection was provided by the bomb shelters dotted around the test site, which sustained hardly any damage even when located just a few hundred metres from the blast.

The explosion lights up the nearest house (top), which is heated by the thermal radiation and torn apart by the subsequent blast wave. The elapsed time between the first and last photos is less than 2.5 seconds

And the mannequins? They had mixed fortunes. Those in the top two floors of the house closest to the explosion were buried under debris and didn’t stand much of a chance. The mannequins in the more distant house suffered a weaker shock, though many of them were injured by debris. “Heads of the mannequins were generally pockmarked and clothing was cut by flying glass,” notes an FCDA booklet published after the test. “Some … had evidence of more serious injury, such as holes the size of a quarter.” The mannequins in the basements of the two houses fared better, coming through the blast unmoved and unharmed.

A silent dinner party in house #2 is rudely interrupted

The living room is turned into a disaster area

Judging from these photos, Operation Doorstep was a pretty vivid demonstration of the devastating power of nuclear weapons. However, it’s somewhat debatable whether blowing up a dummy village can tell us much about the real-life effects of a nuclear bomb. Even if they survived the initial blast, someone this close to ground zero would likely be affected by radiation sickness, either from the initial radiation or from the radioactive material that drifted to the ground after the explosion (the nuclear fallout).

Luckily for mannequins, though, they don’t need to worry about the long-term effects of radiation. This means that they’d probably last longer than us during a nuclear holocaust – maybe that’s what they’re all smiling about…

Photos courtesy of the National Nuclear Security Administration / Nevada Site Office. Click here for a peek inside the now-closed Brading Waxworks  – probably the weirdest museum on Earth.

Superhero Science: Tomorrow’s caped crusaders

6 Jun Superhero Science

This post was chosen as an Editor's Selection for ResearchBlogging.org

Everyone loves a good Hollywood ending. There’s nothing quite as satisfying as seeing a masked hero finally dispatch an evil villain. But aren’t flying men with super-strength a bit passé? Maybe it’s time for some new, cutting-edge superheroes…

Introducing… Corner Woman, Neutrino-man and Camo-Kid (credit: Dave Gray for Guru magazine)

Science and superheroes have a surprisingly intimate history. Pick any of the well-known protagonists from the Marvel or DC comic books and the chances are you’ll be able to trace their history back to science.

Spider-Man, for instance, came into existence when geeky high school student Peter Parker was bitten by a (radioactive) spider during a science demonstration. Some superheroes were even fully-fledged scientists before freak accidents gave them their powers – Bruce Banner (the Incredible Hulk) and Reed Richards (Mister Fantastic from the Fantastic Four) are two examples.

The X-Men, whose superpowers developed from mutations, were undoubtedly inspired by the theory of evolution. Of course, it’s highly unlikely that anyone in the real world is going to start growing claws out of their hands, but mutations are known to play an important role in natural selection, in which a random mutation, if beneficial, can eventually become a new characteristic of a species.

Even Superman – “faster than a speeding bullet, more powerful than a locomotive and able to leap tall buildings in a single bound” – is not quite as unscientific as you might think. In 2007, Dr Chris Stanley at London’s Natural History Museum discovered a mineral with the chemical formula ‘sodium lithium boron silicate hydroxide’. He soon realised that this composition was remarkably similar to the description of a rock containing Kryptonite in the 2006 film Superman Returns. The real mineral, however, is white, powdery and harmless – quite unlike the green, radioactive material that blights Superman throughout his adventures.

Superman plays with himself (credit: JC Hancock)

Clearly, then, there’s a fair amount of science in the world of superheroes. But what type of superhero, I wondered, could be born from today’s cutting-edge scientific research? I decided to browse through some of the recent science news stories and create three science-inspired superheroes of my own. This trio probably won’t be gracing a Marvel comic or Hollywood blockbuster anytime soon, but I hope you’ll take them into your heart anyway.

Continue reading

Quantum physics goes to the movies

30 Mar

This movie shows one of the most beautiful – and mind-boggling – experiments in physics: particles behaving as waves as they pass through a diffraction grating.

Each speck of light represents a single molecule that has passed through the grating. If the molecules obeyed the laws of classical physics – the laws that describe the motion of everyday, macroscopic objects – we’d see a pattern corresponding to the slits in the grating, as if we’d thrown a load of blackcurrants through some railings (as you do).

Instead, we see an interference pattern, even though the molecules go through the grating one by one. This can be explained by each molecule having its own wavefront which goes through all the slits at once – it’s a bit like a blackcurrant turning into a wave (of Ribena?), rippling through all the railings, and combining again into a blackcurrant as it hits the wall. Crazy, I know.

This phenomenon is called wave-particle duality, and this movie is the first time it’s been captured on camera for large molecules. As physicists carry out these kinds of experiments with larger and larger molecules, they’ll be able to understand more about the differences between the world we see around us and the strange, surreal world of atoms and molecules.

If you’re interested in finding out more, I wrote an article about this movie for physicsworld.com – click here to have a read.

Cosmology meets The Beatles

9 Nov

The amusing tale of four scientists who tried to shoehorn The Beatles into their cosmology paper:

This is from the Sixty Symbols collection of physics videos filmed by Brady Haran, a video journalist based in Nottingham, UK.

These videos have been going down a treat on YouTube, and it’s easy to see why – it’s pretty rare to see physics explained in such a personable, engaging way. I’m also probably a little bit biased, as I spent my halcyon undergraduate days in the Nottingham Uni physics department.

If physics isn’t your bag, Brady has also filmed video series on chemistry (Periodic Table of Videos), theology (Bibledex), food (Foodskey), language (Words of the World), and, erm, trees! He also recently launched two new projects about maths (Numberphile) and astronomy (Deep Sky Videos). Phew! To call this man prolific wouldn’t do him justice…

Gunshot Forensics: what’s in a bang?

30 Oct

Imagine you’re a crime scene investigator and you’ve been called to the aftermath of a shooting. There’s been a bloody gun battle between two rival gangs, and you arrive to find a bullet-ridden corpse lying in the middle of a busy street. What would be your top priority?

Some crime scene investigators get to work in CSI

If, like me, your gut instinct would be to get out of there as soon as possible, forensics probably isn’t for you. If, on the other hand, you’re a calm-headed pro, you’d first need to secure and isolate the crime scene. Then you’d photograph the area and maybe start making a note of incriminating evidence such as abandoned weapons or scraps of clothing.

In any case, trying to locate an audio recording of the gunfight probably wouldn’t be at the forefront of your mind.

However, there’s a growing number of forensic scientists who study gunshot sounds, because, surprisingly, a bang isn’t just a bang. Instead, gunshots are like fingerprints: master their subtle differences and you may be one step closer to solving the crime. Continue reading

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