00:00Some men wear shoes with hidden heel lifts to look taller.
00:04Such shoes can make a person up to 6 inches taller.
00:08They look like regular shoes, but inside they have this extra insert.
00:12Sometimes, such an insert is glued down.
00:15Sometimes it's removable, and you can choose the height you need yourself.
00:20When the Titanic hit the iceberg and sank sometime later,
00:24the Atlantic Ocean was around 28 degrees Fahrenheit,
00:27which means the water was below its freezing point.
00:30No wonder so many passengers didn't make it.
00:34Some birds have a row of bristles protruding from the edges of their eyelids.
00:39Those bristles can probably be called eyelashes,
00:42but while human eyelashes are modified hairs meant to protect the eye,
00:46bird eyelashes are modified feathers.
00:50Identical twins don't actually have the same fingerprints,
00:53so you can't blame your misdeeds on your sibling after all.
00:57Different factors during development in the womb, like the position of the womb,
01:01umbilical cord length, and the rate of finger growth, impact fingerprints.
01:06Earth's rotation speed is changing.
01:09It's slowing down right now while we're talking.
01:12It means that, on average, the length of the day gets 1.8 seconds longer every century.
01:18600 million years ago, a day lasted a mere 21 hours.
01:24Most world maps are wrong.
01:26On the majority of maps, they still use the Mercator projection,
01:30which was the first developed in 1569.
01:33But this method is very inaccurate and makes Alaska look as large as Brazil,
01:38while in reality, it's five times smaller.
01:42As for Greenland, it looks 14 times larger than it actually is.
01:46For a map to be precise, it would need to be life-sized and round, not flat.
01:53Ants don't have lungs.
01:55They breathe through tiny openings known as spiracles.
01:58An ant may have nine or ten of those on each side of the body, depending on the species.
02:05The average color of the universe is poetically called cosmic latte.
02:10In a 2002 study, scientists discovered that the light coming from other galaxies
02:14averaged into a beige color that was very close to white,
02:18just like the drink beloved by many.
02:23There is such a thing as minus decibels.
02:25The quietest place on Earth is Microsoft's anechoic chamber in Redmond, USA.
02:31The level of sound there is minus 20.6 decibels.
02:35Such chambers are built out of heavy concrete and bricks
02:38and are placed on springs to stop vibrations from entering the chamber through the floor.
02:45Bananas are radioactive.
02:47Wait, where did you go?
02:49It's not that bad.
02:51Bananas are rich in potassium, so each banana is slightly radioactive
02:54due to the natural isotope potassium-40.
02:58On the other hand, your body contains around 16 milligrams of potassium-40,
03:03so you're actually about 280 times more radioactive than that poor banana.
03:08And in any case, your body gets rid of that excess potassium-40 from a banana within several hours.
03:16There's simply no such thing as a straight line.
03:19You just need to zoom in close enough and you're bound to spot some irregularities.
03:24Even a laser light beam is a bit curved.
03:28In emergencies, fish form orderly lines.
03:31For example, when evacuating through narrow spaces in dangerous situations,
03:36school of neon tetrafish queue so that they don't crash into one another or clog up the line.
03:42Scientists think that this behavior means that fish can respect social rules even in emergency situations,
03:49unlike us humans.
03:52Hippos can't swim.
03:54These animals have large bones.
03:57These bones are so big and dense that it makes hippos barely buoyant at all.
04:01So these animals don't swim.
04:03Instead, they perform something like a slow-motion gallop on the riverbed.
04:08Hippos can also sleep underwater thanks to a reflex that allows them to rise to the surface,
04:14take a breath, and sink back down to the bottom without waking up.
04:21Lego bricks can withstand compression better than concrete.
04:25A regular plastic Lego brick can support the weight of 375,000 other bricks before it breaks.
04:32Theoretically, it could allow you to build a tower more than two miles in height.
04:37But if we decide to scale this up to house-sized bricks, the price would be exorbitant.
04:43If you ever go to space, you can take your yo-yo with you.
04:47In 2012, NASA astronaut Don Petit took a yo-yo on board the International Space Station and used it to show some tricks.
04:55You see, a yo-yo mostly relies on the laws of conservation of angular momentum to perform tricks.
05:01And if you keep the string taut, these laws apply in microgravity too.
05:07There's a theory that claims that we sweat when we're anxious
05:10to alert the brains of other people that they're primed for that danger that's making us feel anxiety.
05:17Brain scans have revealed that when you sniff the sweat produced by a panicking person,
05:21regions of the brain responsible for emotional and social signals light up.
05:26And when you are anxious, your sympathetic nervous system produces hormones, including adrenaline, which switches on your sweat glands.
05:35There are rainbows on Venus, and they're called glories.
05:39A glory looks like a series of colored concentric rings and is caused by the interference of light waves inside droplets
05:46rather than the process of reflection, refraction, and dispersion of light, which produces rainbows.
05:53Protons look like bagels, spheres, peanuts, and rugby balls.
05:58In other words, protons come in different shapes and sizes.
06:01Their appearance changes based on the speed of quarks, smaller particles within them.
06:07If you look at the moon while being in the southern hemisphere, it will seem to be upside down,
06:12and the men on the moon will look more like a rabbit.
06:16You will remember more of your dreams if you sleep badly and wake up many times throughout the night.
06:21You're also more likely to remember your dream if someone or something wakes you up in the middle of it.
06:27Dogs tilt their heads while listening to people to pinpoint familiar words, like walkies, more effectively.
06:34It also helps them to understand the tone of your voice better.
06:37There's also an idea that if a dog doesn't tilt its head often, it's because it relies more on sight and less on sound.
06:47Mirrors facing each other won't produce infinite reflections.
06:50Each next reflection will be darker than the previous one, and eventually, they will fade into invisibility.
06:57Mirrors absorb just a fraction of the energy of the light falling on them,
07:01so the total number of reflections mirrors can produce is around several hundred.
07:07You can smell ants, since many species of these insects produce strong-smelling chemicals when they feel threatened or angry,
07:14or when they're being squished.
07:16Trap-jaw ants release a chocolatey smell when they're crushed,
07:19and citronella ants give off a lemony odor when they're threatened.
07:25Giraffes hum when they want to communicate with each other.
07:28Researchers think that this low-frequency humming might be a form of contact call between individuals that have been separated from their herd.
07:37It can also help giraffes find each other in the dark.
07:40But the coolest thing about these magnificent animals?
07:43Some scientists think that they can sleep-talk too!
07:49And a cool bonus story for you,
07:51about a marathon runner who took over 50 years to finish the race.
07:56Japanese marathoner-runner Shizuo Kanakuri was selected as one of the two athletes that Japan could send to the 1912 Stockholm Olympics.
08:05But Kanakuri shockingly disappeared during the marathon race.
08:09It turned out that after a rough 18-day-long trip to Stockholm,
08:13first by ship and then by train,
08:15the man was exhausted.
08:17During the race, he stopped running because his condition simply didn't allow him to run further.
08:22The athlete stumbled into a nearby garden party where he drank orange juice and stayed for a while to recover.
08:29Later, Kanakuri was so embarrassed by his failure that he returned to Japan without notifying anyone, including race officials.
08:38So, Swedish authorities considered him missing for 50 years before finding out that he was peacefully living in his home country.
08:46In 1967, the athlete was offered the opportunity to finish his run.
08:50He accepted.
08:5254 years, 8 months, 6 days, 5 hours, 32 minutes and 20.3 seconds after he started the race, he completed the marathon.
09:01It was a long trip.
09:03Along the way, the man got married, had 6 kids and 10 grandchildren.
09:20He died.
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