QI. Image shows from L to R: Alan Davies, Sandi Toksvig. Copyright: TalkbackThames.


BBC Two and BBC One panel show about quite interesting facts. 266 episodes (pilot + 18 series), 2003 - 2020. Stars Sandi Toksvig, Stephen Fry and Alan Davies.

Returns Wednesday 23rd December at 9pm. Episode Guide
Series P, Episode 4 is repeated on Dave today at 9pm.

Series G, Episode 12 - Gravity

Further details

QI. Image shows from L to R: Bill Bailey, Stephen Fry, Barry Humphries, Rich Hall. Copyright: TalkbackThames.


- You can get from where you are to anywhere else in the world in exactly 42 minutes and 12 seconds by travelling through the Earth. Theoretically speaking, if there was a hole that went through the planet and you jumped down it, it would take you 42 minutes and 12 seconds to fall through to the other side because of the gravity. The maximum speed you can travel at depends on where the tunnel is. This tunnel does not have to grow straight down the middle of the Earth. It can be placed anywhere, and it would still take you the same time to come out of the other end. This is known as a "Gravity train" and while it is not feasible on Earth, it might be on the Moon because it has no molten core, but it would take 53 minutes to travel through it because the gravity is weaker. The people who worked out the information regarding the 42 minutes and 12 seconds were Sir Isaac Newton and Robert Hooke, in a series of letters between them.

- Tangent: An antipode is a place on Earth where dry land is located on the direct opposite side of the Earth. England to Australia is not an antipode, but amongst the places that are antipodes include several places along the equator, as well as Indonesia to Colombia. There was once a contest to make an "Earth sandwich" in Canada, in which the idea was if you had two pieces of bread big enough, where could you place them so you could hold the Earth without it getting wet. Two brothers declared New Zealand to Spain to be an antipode, but there was controversy because they used baguettes for pieces of bread. If you are a Muslim, Mecca's antipode is an atoll in the Pacific known as the Tematagi, also known as Captain Bligh's Atoll, which is quite interesting because it is the only place on Earth where you can be in any direction which faces Mecca.

- XL Tangent: Alan references the film "Brazil" in which tubes are placed in vacuums and that you could use a similar tube to send stuff to an antipode. Stephen then references the old change machines in shops that worked on a similar principle. Someone would wrap the money in a docket which said how much money everything was worth. This was put in a cylinder, placed in a vacuum that sent it to another part of the store, and then you waited for the cylinder to return with your change. Rich then brings up the subject of the unusually strong vacuum on aeroplane lavatories and then talks about a pest-control man in Montana who used a vacuum device called a "grain elevator" to get rid of prairie dogs for those who did not want them killed. However, the force of the vacuum gave the prairie dogs brain damage. When Rich asked the man what he did with the prairie dogs afterwards, he said he led them to a river and let them go. Then the man would wait a few days and get rid of them again on the other side of the river.

- While Aristotle believed that heavier objects travelled towards the Earth quicker than lighter ones, Galileo realised he was wrong by calculating it, not by demonstrating it. He later did some experiments using ramps, but he never dropped anything from a great height. Galileo worked out that half a tonne of coal would fall at the same speed as one tonne of coal. Galileo worked claimed correctly that Aristotle's reasoning, if a lighter object was attached to a heavier object, then either the added weight would make the whole thing travel faster or the lighter object would slow the heavier one down, meaning it would be going faster and slower at the same time, which is impossible. Apollo 15 astronaut David Scott demonstrated that Galileo was right by dropping a hammer and a feather on the Moon, which both landed at the same time. (Forfeit: Dropping cannonballs of the Leaning Tower of Pisa)

- In 1784, Britons George Biggin and Letisha Sage performed not only the first hydrogen balloon flight, but could also be argued to be the first members of the "Mile High Club" by having sex in their balloon. It was organised by an Italian called Lunardi who was meant to go with them, but he got out thinking the balloon would not support three people. He got out just as it took off in St. George's Fields, and as the balloon flew over Piccadilly people could see Sage on all-fours, although she tried to make excuses claiming she was not having sex. The balloon travelled 14 miles, landing in Harrow. The incident became a huge scandal, with people asking having sex in a balloon was possible at all. The wager books, which contain lists of all the bets made in London clubs, contained one bet which read: "Lord Cholmondeley has given two guineas to Lord Derby to receive 500 guineas whenever his lordship 'plays hospitals' with a woman in a balloon 1,000 yards from the Earth."

- XL Tangent: In the earliest days of ballooning, they used barometers as altimeters, because they could detect changes in atmospheric pressure.

- Tangent: The first people to fly a hot air balloon across the English Channel were a Frenchman called Blanchard and his American backer called Jeffries. However, they hated each other. Blanchard tried to carry lead weights on a belt, claiming that there was only room for one of them to ride the balloon and that Jeffries should get off. Jeffries spotted the bluff and made Blanchard take the belt off. When in flight, they "accidentally" dropped each others national flags off the side of the balloon. The balloon then started to drop too early so they tried to make the balloon lighter, first by getting rid of their food, then their instruments, their sandbags, their coats and their trousers. Then they urinated out of the balloon, then defecated out of the balloon, and they just got over the White Cliffs of Dover.

- The thing to say to a gossypiboma is actually something to say to a surgeon, and normally something like "Get it out!" A gossypiboma is something that a surgeon leaves inside your body, like a piece of cotton, although it could be anything. In the USA, there are 1,500 cases a year of things being left inside the body by surgeons. 54% of foreign bodies are left in the abdomen or pelvis, 22% in the vagina, 7.5% in the chest and 17% in other places like the spinal canal, the brain and the face. One man had a six-inch surgical clamp insdie him, but the surgeons realised that the man already had an operation to remove a clamp. He had two in there and the previous surgeon never thought to find the other one. The reason given by surgeons for why this happens is because in unprepared medical emergencies there are unplanned changes in the operation and thus people forget about what things were used. Also, they blame patients with high body mass indexes because it is harder to find stuff inside someone who weights more. While "gossypiboma" is the most common term used by surgeons, because it relates to cotton, if a surgical instrument is left inside the body it is called a "foreign body granuloma". Perhaps somewhat cheekily, when a foreign body is discovered, they refer to it as being "retained" by the patient as if it was the patient that took it rather than the surgeon leaving it behind. (Forfeit: Mind your own business)

- XL: An underwater weighting machine is more accurate in calculating body mass index than one on the surface. The body mass index (BMI) is equal to your weight divided by your height squared. However, the system is very faulty. For example, if you are very muscular, the BMI would say you are overweight, while if you were a marathon runner with a slower metabolism the BMI would say you were underweight. Therefore, for really accurate measurements, you are weighted underwater. Under the BMI, you are considered overweight if your BMI is over 20 for men and over 30 for women. (Forfeit: Whale weigh station)

- XL: Stephen asks a question which he asked Alan last year, who told Stephen that it would make a good QI question: "Why, when you slow down, do you become more unstable on a bicycle?" The answer is a mixture of torque and the caster effect, which is when the back wheel acts on its own and self-centres. To turn a bike left, you turn the handle bars slightly right in what is known as counter-steering, which makes it difficult to go around kerbs. If you want to test it, ride a bike, take you left hand off, and then turn the handle with your right. Although you can only push them left, you will go right. The physics of bicycles was not understood until 1970 by David Jones.

- XL Tangent: Rich points to the photo in the background which features photoshopped images of Stephen and Alan on bicycles, and asks Stephen why he has a Hitler haircut in the photo. Bill once cut his to like Hitler's and dyed it black to play the role of Arturo Ui in a "The Resistible Rise of Arturo Ui". When his mother saw him, she said: "Oh, now, that DOES look nice. You look very smart."

- XL Tangent: In Cambridge, they tried out the idea of leaving bicycles around the place for anyone to use. People would take them, ride them and leave them for someone else to use. Within two days all the bikes were stolen.

- Shooting a gun straight up into the air in a celebratory mood is a bad idea because the bullets have to come down, and they come down with some force. While it is unlikely they the person firing the gun will get hit, because a single gust of wind will blow the bullets away from the them, the bullet may still land on someone nearby and crack their skull. A typical 7.62mm round would typically reach a height of nearly 2.5km, taking 14 seconds, and then it would take another 40 seconds to come back down again at a speed of around 70 metres per second.

- Tangent: If you had a loaded gun in one hand and a bullet in the other, held them at the same height, and then dropped the bullet and fired the gun at exactly the same time, they would land on the ground at exactly the same time, because they both have the exact same force - gravity - operating on them. Some things may stop it however. For example, if the fired bullet travelled at five miles per second, it would leave the Earth's atmosphere and never land. If it went far enough, the fired bullet might have further to fall because of the curvature of the Earth.

- Supposing you invaded London, but the "oppressors" had fled to the Welcome Break Motorway Service Station at Scratchwood, which are the first services if you got out of London via the A1. If you were in the City of London but have cut off all telecommunications so you cannot give instructions to anyone outside, you could stop your oppressors using the guns on HMS Belfast, which are pointed at Scratchwood Services. If you go on board as a tourist, you will see a sign telling you that they are pointed at Scratchwood Services.

- Tangent: The luckiest ship in the US navy is considered to be USS Phoenix, as it was the only one not to be hit during the attack on Pearl Harbour. It was sunk in 1982 but it had changed its name after it had been sold to the Argentineans. It was the ARA General Belgrano, which was sunk during the Falklands War killing over 300 people and is so far the only ship sunk by a nuclear submarine.

- XL: Fosbury flopped because it lowered his centre of gravity. All the jumps before that in the high jump - the scissors, the Eastern cut-off, the Western roll and the straddle - placed their centre of gravity above the bar. The Fosbury flop, introduced in 1968, places the centre of gravity below the bar, meaning you can jump higher for no extra effort. The world records for the high jump were set in 1993 for men and 1989 for women, so it looks like they are getting harder to beat.

- XL Tangent: Jesse Owens held the world record for the long jump from 1935 to 1960.

- XL Tangent: Bill once lost a charity limbo competition to Lionel Blair and Sinitta.

General Ignorance

- If a cloud rained wine, it would have to be the size of a bus in order to dispense your daily recommended amount of wine (250ml).

- XL Tangent: In Britain, 21 units of alcohol per week is the recommended allowance, but in Poland it is 12.5, in Canada 23.75, in the USA 24.5, in Denmark and South Africa 31.5 and in Australia 35. However, if you drink between 21-30 units, you belong to a group of people who have lowest mortality rate in Britain. You actually have to consume 63 units per week, or one bottle of wine a day, to have the same death risk as a teetotaller. The man who invented the system admitted the number was made up. Lifestyle and problems with drunk are more likely to harm you.

- There are five bullets in a gunslingers revolver. One is always empty for safety reasons. Wyatt Earp claimed that he always left the sixth chamber empty because the hammer rested on the chamber and so he knew it would not backfire by mistake. (Forfeit: Six) Correction: Earp's gun actually had a 'quarter-cock' position, which holds the hammer completely clear of the cartridge, meaning Earp knew that it was safe.

- Tangent: Stephen met an armourer who worked on Westerns since the 1930s who claimed that he saw only two actors who did not blink when they fired a gun: Clint Eastwood and Yul Brynner.

- If you cook a stake and you see a red liquid come out of it, that liquid is myoglobin. It is a protein used to help muscles work during sustained activity. (Forfeit: Blood)


- Rich Hall and Alan Davies: 3 points (Alan's eleventh victory and first joint victory)
- Bill Bailey: -8 points
- Barry Humphries: -36 points


For correction, see QI Qibble Blog.

Broadcast details

Friday 12th February 2010
30 minutes

Cast & crew

Regular cast
Stephen Fry Host / Presenter
Alan Davies Regular Panellist
Guest cast
Bill Bailey Guest
Rich Hall Guest
Barry Humphries Guest
Writing team
John Mitchinson Question Writer
Justin Pollard Question Writer
James Harkin Question Writer
Molly Oldfield Question Writer
Production team
Ian Lorimer Director
Piers Fletcher Producer
Katie Taylor Executive Producer
David Morley (as Dave Morley) Executive Producer


What Goes Up...

Stephen asks what happens if you fire your gun straight up in the air.

Featuring: Alan Davies, Stephen Fry, Bill Bailey, Rich Hall, Barry Humphries.


Supporters and subscribers get more

Additional content and tools are available across the site for Supporters and BCG Pro subscribers. On this page you can:

  • See 2 press clippings related to this episode
  • Broadcast details of 33 further repeats of this episode
  • BCG Pro business users can see additional crew credits  
    If you join BCG Pro business, you can see composer, editor, production designer & researcher credits for this episode.

Donate (for fans) BCG Pro

Already a donor or Pro user?