Themes

- All the buzzers are songs with the word "move" in them. Danny has: "I Like To Move It" by Reel 2 Real; Marcus has: "Moves Like Jagger" by Maroon 5; Jo has: "Moving On Up" by M People. Alan however has "Saturday Night at the Movies" by The Drifters, but this still appropriate as cinema was originally called "kinema", which comes from "Kinetic".

Topics

- If you balance a broom on the side of your hands and move your hands together they will naturally move towards the centre of gravity, which means the broom will balance on top of both hands. This is because the weight of the brush causes resistance at the heavier end so one hand will travel a shorter distance and the other hand will move further. It is also easy to balance the broom with the brush facing upwards, however Stephen is told that the balancing it the brush facing down is much harder. Despite this Alan manages to do it, and Stephen rips up the question card he has been given. The centre of gravity was discovered supposedly by Archimedes.

- XL: Stephen is 6ft, 4.5in tall and weighs just over 14 stone. However, if Stephen was 44,000 miles tall and had the same rations and proportions Stephen would not weigh anything because his centre of gravity would be beyond the Earth's gravitational pull and thus Stephen would be in orbit. Coincidentally, if Stephen's proportions were scaled up, his penis would be 3,384 miles long.

- XL Tangent: As mentioned on a previous QI, there was once a proposal to build a space elevator to get out into space, which uses the same ideas concerning the centre of gravity escaping Earth's gravity.

- XL Tangent: Nobody knows which way the Earth is up. The North Pole is not strictly speaking facing upwards relative to the rest of the universe. In Australia you can buy globes with the southern hemisphere on top.

- XL Tangent: QI has been mentioned in the Australian Parliament because one MP complained about Australian tax payers not paying for home-made Australian programmes but they do pay for wall-to-wall "bloody Stephen bloody Fry", because the show gets repeated a lot down under. Stephen apologises and says you do not have to watch the programme.

- XL Tangent: Danny once talked to British astronaut Michael Foale two months before this recording, who has been in space three times. Foale's told Danny that the most important thing when repairing craft from the outside is to hear the message: "Gentlemen, two minutes to sun-up." Here you must put your sun visor down because the sun is so much brighter outside of the atmosphere and is more dangerous than it is on Earth. Also, spacesuits cost £35,000,000 each, are bespoke and are measured two years in advance.

- XL: The most interesting thing you can do with a hole, a stick and a Greek man is measure the circumference of the Earth. Eratosthenes of Cyrene put a stick into a well during the summer solstice, because he knew that no shadow would show, and had another stick stuck in another place 500 miles away. He could use the shadow of the second stick to calculate that the Earth's circumference was about 25,000 miles. The actual figure is 24,859 miles, so Eratosthenes's margin of error was less than 1%. Eratosthenes was the librarian at the library of Alexandria, the Ancient World's greatest repository of knowledge. He was also a musician, astronomer, poet, inventor of the term "geography" and mathematician. He was known as "Beta" because he was the second best in every discipline known.

- XL Tangent: The picture used to during the question features a young boy in traditional Greek dress. The boy is of a nine-year-old Prince Philip, who was born in Greece and is often nicknamed "Phil the Greek".

- If the Earth suddenly stopped spinning then we would probably collide into whatever is next to us at high speed. The Earth spins at 1,000mph at the equator which is not fast enough so that you would fly off it because the Earth still has gravity. The Earth would need to spin 17 times faster in order for people to fly off it. The other major effect of the Earth no longer spinning is that half the planet would be plunged into eternal darkness, so most people would be rushing to emigrate to the side that was always in light. Also it would cause confusion amongst just about all animals. (Forfeit: We'd all fall off)

- XL Tangent: Marcus once started writing a book called "The 25th Hour" in which due to a cosmic event a day on Earth lasted an extra hour. To start with everyone wonders what to do with their extra free time, but later banks and businesses try to get hold of it and make everyone work for the extra hour. However, it turns out that time available sits perfectly balanced against greed, so when you increased one and not the other it all collapses. However, according to his publisher someone else had already written a similar novel - at least this was the excuse his publisher gave.

- The thing that travels the wrong way along a motorway at 12mph is a phantom traffic jam. This is caused when one car suddenly slows down, then it speeds up again. The car behind it will also slow down, and speed up again. This ripple effect travels downwards causing more cars to slow down until eventually they jam up. (Forfeit: A mobility scooter)

- Tangent: China has the worst traffic jams in the world. There was one in 2010 that was over 80 miles long and moved on average less than 1km a day. They are so bad that there is now a service in China where two people turn up on a motorbike and the car driver swaps places with one of the bikers, so the biker looks after the car while it is in traffic while the car driver is weaved through the traffic to their destination.

- Tangent: Marcus went to Las Vegas and spotted a billboard truck which advertised hookers to your door in 25 minutes. However, he also noticed that pizza takes 30 minutes to arrive to your door, so he calculated that if you had the resources it would be easier for the hooker to pick up the pizza for you.

- When it is raining heavily mosquitos can brush the raindrops aside or even ride them, despite the fact that a single raindrop is 50 times heavier than a mosquito.

- Tangent: Danny claims that he cannot remember mosquitos in Britain as a child, but now we have loads of them. He says that the only way to avoid mosquitos if you are holding an outdoor barbecue is to hang a blood bag by your neighbour's house. There is now a special sub-species of mosquito that lives only on the London Underground which bites rats, dogs and people called Culex pipiens molestus.

- If it is raining it all depends on the shape of your body and the direction of the rain on whether or not walking or running is the best way of getting less wet. According to Prof. Franco Bocci, who wrote an academic paper on this subject for the European Journal of Physics, he states the following: If the rain is falling straight down or is blown towards you, run as fast as you can. If the wind is behind you then try to match the speed of the wind. If the wind is from the side then fat people should run as fast as they can while thin people might be better off walking.

- You might well remember when snails were faster, because it appears that they are slowing down. Chilean scientists took some common garden snails and measured their metabolisms by the amount of carbon dioxide they emitted at rest. They then released the snails into the wild, and later went out to and found that some snails were alive and some were dead. They discovered that the snails with slower metabolic rates lived longer, so slower snails are more likely to survive.

- Tangent: Stephen tells an old joke about a builder who turns around and stamps on a snail and says: "That bastard's been following me around all day." Alan tells another joke in which a snail knocks on a door, the man answering picks the snail up and throws the snail away, and two days later the snail knocks on the door again. The man answers and the snail just exclaims: "What?" There is a hint of truth in these jokes because if you through a snail it will try to return to the spot they were thrown from.

- Tangent: As mentioned on a previous episode of QI, snails were the first animals to be farmed.

- The biggest swingers in Europe are the Estonians. This has nothing to do with any sexual activity however. The Estonians have a national pastime called "Kiiking", which involves standing on a metal swing and using just your own body make it swing around a full 360 degrees. The swings arms are adjustable telescopically, so the arms move every round making the swing longer and more difficult to rotate, and people get eliminated like in the high jump until there is one person left. Estonia is one only three countries, the others being Hungary and Finland, whose language makes up the Finno urgic linguistic family. (Forfeit: Germans)

- Tangent: Marcus jokes that he got a UKIP leaflet saying that all immigrants would enter Britain using swings.

- XL Tangent: Some children today put a moped on its side and put the back wheel against the bottom of a child's roundabout to make it spin incredibly fast. The panel talk about when in the old days people would dump dog poo and used needles in the park sandpit, and that dog poo used to be white in colour. Now the common bad thing done with dog poo in parks is putting it in a bag and placing it back where the poo was or hanging it off trees.

- XL: When Vesuvius erupted most of the people in Pompeii managed to escape. 1,100 bodies have been found in Pompeii but at least 15,000 people lived there. One resident who did not escape was QI "patron saint" Pliny the Elder, who sat on a chair and tied a pillow to his head with a napkin to observe the eruption. Most of the ash-frozen bodies you see are casts. Many of them when they were discovered were filled with plaster of Paris.

- The world's highest waterfall, in terms of length of drop, is underwater and has no name. The drop is 11,500 feet, compared to Angel Falls which is only 3,212 feet, and is located between Greenland and Iceland. It is deemed a waterfall because there is a huge current of cold water that drops down. It carries at least 175 million cubic feet of cold water per second, the equivalent of 2,000 Niagara Falls' at peak flow. (Forfeit: Angel Falls)

- XL Tangent: These kind of underwater waterfalls matter considerably with regards to the melting ice caps, because ice caps have very cold water which is very dense and drops quickly, thus drawing warm water from the ocean bed past Western Europe. However, if this process stops then it could trigger a massive ice age. Marcus went to the arctic ice cap with a search vessel and during the trip he went to the east coast of Greenland and entered a fjord. The ship's crew wanted to film Marcus floating between the icebergs. So he got into a survival suit and as he climbed down the ladder he heard a crew member say: "Oh, there's a seal in the water." Marcus thought this would make the film better and as he let go of the ladder he could hear the same man say: "Oh hang on, that's not a seal, that's a bear." It was a mother bear with two cubs on her back, making her slower and thus allowing Marcus to escape.

- The world's biggest river is in the sky. Atmospheric rivers carry more water than any river on the surface and are vast ribbons of water vapour that move water around the world. They appear at different places at different times and can be 2,000km long, but a just a few kilometres wide. They cover less than 10% of the globe but four or five of them contain 90% of all the world's water vapour at a time. (Forfeit: Underwater; Amazon; Nile)

- The world's biggest river that is NOT in the sky is underground. The Rio Hamza is a river under the River Amazon that was discovered in 2011. Data collected from 241 abandoned deep wells shows that the Rio Hamza runs 6,000km like the Amazon above it, but is up to four times wider, between 200-400km wide. It is 4km below the actual Amazon. Some people may say it is more of an aqua-flow, but it flows horizontally like a river does.

- The world's biggest animal really is the blue whale. It is the largest animal ever to have existed - and still Alan fails to answer the question right, as Marcus gets there first.

- Knick-Knack Experiment - It is possible to knock down a building with a feather. You can do this using a domino effect, but using increasingly larger dominos, each one being one-and-a-half times bigger than the one before it. Stephen shows this by arranging a set of dominos that start off with a very small one and get increasingly larger. The smallest domino can knock down a slightly larger one, which is able to knock down a slightly larger one and so on. You would only need 24 of these dominos, growing at the same rate, to knock over a building the size of the Shard.

Scores

- Danny Baker: 8 points
- Marcus Brigstocke: -5 points
- Jo Brand: -8 points
- Alan Davies: -56 points