Tom Scott

If you're sitting on a boat in Lake Constance, are you in three countries at once? Or just in one? Does it even matter? Because strangely, it turns out there are parts of the world where no-one really minds when international borders are not just ignored, but are completely undefined.

I thought about saying "secret patterns" or "mysterious patterns" in the title, but that'd be a lie: they're just mostly unknown! So let's talk about tactile paving, about design, about accessibility, and about those bumpy bits that you stand on when you're crossing a British street. // Thanks to Richard Holmes and the team from the RNIB!

In Bremen, Germany, there's a tower more than a hundred metres high: it's called the Fallturm, or the Drop Tower. If you want a cost-effective way to test an experiment in microgravity -- and your project can survive some pretty strong deceleration -- then this might well be a good place for you. And then there's the slingshot...

The Jelling Stones, thousand-year-old Viking runestones, sit in the town of Jelling in Denmark. They tell the tale of Harald Bluetooth: one of the first kings of Denmark. Here's why his name is on your phone.

Near the town of Herning in Denmark sits Elia, a giant metal dome sculpture by Ingvar Cronhammar that occasionally spouts flame. I reckon it's the world's most frustrating piece of art, and here's why.

One woman's face is all over New York, although you've probably never heard of her. This was written with Amor Sciendi: go check it out!

I never thought of sand as a non-renewable resource, but there's only a limited supply: and to make things worse, it keeps getting washed into the sea. At Cape May, New Jersey, the US Army Corps of Engineers have just finished rebuilding a beach: here's why.

At YouTube Space New York, there's the Mixed Reality lab: a virtual reality setup using an HTC Vive, a third controller, and some fancy compositing equipment. It's brilliant, and I got to visit and look behind the scenes.

In Belgium, there's an underground beer pipeline. Yes, it's inherently difficult to film something that's underground, but I headed over to Bruges to investigate anyway.

Yttrium, terbium, erbium and ytterbium were all named after one small town on the Stockholm archipelago. But it could have been different, and there could have been many other names. From a snowy bit of Sweden, and a mine that's a historical landmark, let's talk about discovery, chemists, and a man named Gadolin. Thanks to Paul (@cr3) on camera, and to @de_isja, @Ekkelos, @chemician and Chris Armstrong for proofreading the chemistry in the script!

Hot and cold water sound different when you pour them. When Steve pitched this to me, I didn't believe it, and then he sent me a couple of sound files, at which point I knew this was going to be the first of the guest videos!

The Hyatt Regency Hotel collapse was a disaster that changed engineering: it's taught in colleges and universities as a way to make it clear: you check and double-check everything. Something that seems like a subtle change can cause a catastrophic failure if it's not thoroughly checked first!

Amy brings with her one of the greatest props I've ever seen: an actual piece of Kapton foil from Apollo 11. This tiny little sliver of material went around the moon, and helped keep three people safe as they blasted out of our atmosphere and back. Here's why it was there, and why it changed colour!

It's been a long time since I did a linguistics video, but today Alex has stepped in and done a brilliant job. Song translations usually suck: and it's because you either have to lose the meaning or the sound. Let's talk about syllabic vs melisamatic singing, about music, and about Beethoven.

Splenda is a "zero-calorie sweetener", at least in the US. Or at least, that's what it says on the packet. With the help of some Benedict's Solution, and his chemistry teacher, Alex is going to do some food science.

At the University of Manchester's High Voltage Laboratory, we see what happens when a DJI Phantom 3 drone gets hit with an electrical impulse of 1.4MV - basically, a lightning strike. Actually, two Phantom 3 drones. We had a backup.

The Voyager 1 space probe is the furthest man-made object from Earth, and the fastest. But right now, it's moving towards us. Relatively speaking. At Mission Control for the Deep Space Network, inside NASA's Jet Propulsion Laboratory in Pasadena, let's talk about why -- and about how to stay in touch with something so small and so far away.

The Mars Yard, at NASA's Jet Propulsion Laboratory, is one of the closest simulations of Mars that we've got. Admittedly, there's a bit more atmosphere and gravity, but it's the only way to test what might happen before sending commands to a rover that's light-minutes away.

There's a reason that a lot of planets in American science fiction look the same: they're all filmed in the same places. But why those particular locations? It's about money, about union rules, and about the thirty-mile zone -- or as it's otherwise known, the TMZ.

The radio telescope at the Arecibo Observatory in Puerto Rico can do something that most radio telescopes can't: it can transmit. And that's useful for something other than sending messages to the stars: it might just help save the world one day.

The mysterious YouTube algorithm. It's confused people for years, and will continue to do so. So why isn't YouTube more transparent? It used to be that they wouldn't tell anyone how it works - but now, it's that they can't. Let's talk about deep learning algorithms, neural networks, and search engine optimisation.

Near Bodø in Norway, there's the strongest tidal current in the world: Saltstraumen Maelstrom, a constantly-changing rush of whirlpools, boils and vortices. It might not be quite the whirlpools of myth and legend, but it's still an impressive sight to see.

Inside the beautiful Alnwick Garden, behind a locked gate, there's the Poison Garden: it contains only poisonous plants. Trevor Jones, head gardener, was kind enough to give a guided tour!

I'm not saying this would be a good idea, and it's definitely not a prediction of the future. It's just a story. I think. An Evening of Unnecessary Detail runs once a month from January to June at the Backyard Comedy Club in London: thanks to all the team there, including Matt Parker and Hannah Fisher! Tickets at http://aeoud.com

In Helsingborg, Sweden, the Museum of Failure has just opened. It's just one room, but inside, curator Samuel West has assembled some of the world's greatest commercial disasters - and also a few things that just didn't work out the way anyone planned.

Landing on a runway surrounded by fire might not sound like a good idea, but it's better than trying to land without modern instruments in thick fog. This was FIDO: "Fog, Intensive, Dispersal Of" (originally "Fog Investigation and Dispersal Operations"), the Royal Air Force's strange but brilliant scheme that saved thousands of air crew lives. Unlike a lot of World War 2 experiments, this one not only worked, but was deployed around the country. It would have been used in peacetime, too, except for one rather big problem: petrol's really expensive.

I've filmed a paternoster lift; I've filmed the strange Genoa elevator that sort-of goes sideways. So when I got an email from Thyssenkrupp, an elevator company, saying "come and see our Multi elevator that actually goes sideways", I wasn't going to turn it down. Full disclosure: Thyssenkrupp paid for my travel to Germany, but that's all they did. I'd got in touch with them last year asking to see this when it opened; their PR firm replied, offering to fly me out. They had no editorial control over this, and didn't get to see it before it was uploaded!

Encryption backdoors - breaking WhatsApp and iMessage's security to let the government stop Bad Things - sounds like a reasonable idea. Here's why it isn't.

Last week I made a video surrounded by old-school CRT monitors and televisions - cathode ray tubes. And I completely forgot to remove the high pitched whine they produce. Here's why: why they make that noise, and why I didn't notice it.

I can show a brighter pink. I can show a more saturated pink. But I can't show you this pink. Not quite. More about Stuart Semple and his pigments: https://www.culturehustle.com/ [that's his store, we overloaded Stuart's personal web site, http://www.stuartsemple.com, within a few minutes...!] (I reached out to Anish Kapoor's studio twice for comment; I didn't get any response.)

There's an MRI scanner in Cardiff that can look at how the brain's wired up: your connectome. It's nowhere close to science fiction singularity brain-uploading, but it might well be part of unlocking new medical treatments in the years to come. Thanks to Prof. Derek Jones, and to all the team at CUBRIC : http://sites.cardiff.ac.uk/cubric/ -- and to the Cardiff University film crew with their gimballed camera!

There are a lot of opinions on how to hire coders, and most of them are terrible. The opinions, that is, not the coders. But a basic filter test to make sure someone can do what they say they can: that seems reasonable, and FizzBuzz is one of the more common tests. Even now, interviewers use it. Let's talk about why it's tricky, and how to solve it.

I'm at the top of Mount Evans, more than 14,000 feet - 4.3km - above sea level. This is definitely a mountain: but why doesn't the smaller summit next to it also count? Let's talk about prominence. (Just not for too long, I'm getting low on oxygen.)

Welcome to the US National Ice Core Laboratory in Denver, Colorado, where there's a giant freezer filled with 20km of ice cores from Greenland and the Antarctic. Here's why. Thanks to everyone at the US National Ice Core Laboratory! You can find out more about them here: http://icecores.org/ The Ice Core Laboratory is supported by the National Science Foundation: https://www.nsf.gov/

The National Institute of Standards and Technology, NIST, sells Standard Reference Materials, or SRMs for short. They're analysed, quantified, and certified substances: everything from metals, to elements, to food items... to, yes, freeze-dried urine.

In Weldon Spring, Missouri, there is a strange, grey, windblasted seven-storey pile of rocks. It's the Weldon Spring Site: a nuclear and toxic waste dump on the site of an old uranium processing factory. And you can walk on it: it's technically a tourist attraction. That was going to be the whole of my video... and then I did some more research.

Computers store text (or, at least, English text) as eight bits per character. There are plenty of more efficient ways that could work: so why don't we use them? And how can we fit more text into less space? Let's talk about Huffman coding, Huffman trees, and Will Smith.

In Crawfordsville, Indiana, there's a rotary jail: an invention that, with hindsight, should probably never have been built. But it was, here and in other towns across the United States. It might have sounded like a good idea on paper, but in practice, it had a few unfortunate problems... including occasional accidental amputations.

In the archives of Yale University, there's a 367-year-old bond from the water authority of Lekdijk Bovendams, in the Netherlands. And it's still paying interest.

On the river Rhine in Switzerland, there are reaction ferries: boats with no engine, no paddles, no onboard motive power at all. Here's how they work -- and a question about what other simple ideas are out there.

In Lancaster, California, there's a musical road. When you drive over it, it plays the William Tell Overture. Unfortunately, it's out of tune. Here's why.

In Calipatria, California, the town is below sea level -- but their flag pole isn't. But what does "sea level" mean? Is it just theory, or is there more behind it?

Near Slab City, California, a man painted a hill. It was outsider art: Leonard Knight had no training and no great masters to imitate. But somehow, he created something that resonates with the world. This is the story of Salvation Mountain. Thanks to Ron and to all the team at the mountain; you can find out more about them here: http://salvationmountain.org/

At the headquarters of Cloudflare, in San Francisco, there's a wall of lava lamps: the Entropy Wall. They're used to generate random numbers and keep a good bit of the internet secure: here's how. Thanks to the team at Cloudflare - this is not a sponsored video, they just had interesting lava lamps! There's a technical rundown of the system on their blog here: https://blog.cloudflare.com/lavarand-...

I'm visiting the University of Iowa's National Advanced Driving Simulator, to answer a question: how unsafe is it for me to vlog while driving? Is vlogging while driving dangerous? The team at the simulator are the experts to ask.

The town of Staufen, in the south-west of Germany, has a problem: a drilling operation in 2007 that went very wrong. Half a metre of movement might not sound like much, but in this town, that's enough for the buildings to crack and fall apart.

It's not your imagination; hold music on phones really did sound better in the old days. Here's why, as we talk about old telephone exchanges and audio compression.

There's a link from a 13th century legend, to a 16th century insult book, to a 19th century writer, to a 20th century comic book hero. And it starts in a small village near Nottingham, in the time of Robin Hood. Here's why Batman comes from Gotham City. (I am reliably assured that the modern-people of Gotham are not, in fact, fools.)

The European Space Agency offered me a seat on their zero-g plane: it's an Airbus A310 that flies parabolic maneuvers, pulling up into the sky and then arcing back down, giving its passengers about 20 seconds of weightlessness (or "microgravity") at a time. Here's how it works. Some people would have filmed their script on the ground, and just messed about while floating. I decided to go for something a bit more challenging.

While I was trying to read a script to a camera in zero-g, the student researchers behind me were trying to prove their own ideas -- or rather, to disprove their "null hypothesis". Let's talk about how science works -- and have a look at one of the teams flying in that plane.

Hold on tight, because with a stabilised camera shot and a pair of sunglasses, you're about to see a video that works in both 2D and 3D at the same time. The technique's called the Pulfrich Effect, and this is how it works.