Les gardes royaux doivent suivre un protocole en cas d'évanouissement + D'autres faits uniques

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Transcript

00:00:00Can you hear a sound and perceive almost instantly a specific color?

00:00:06You could be part of a particular group of people, about 4% of the world's population,

00:00:12capable of experiencing synesthesia.

00:00:15It's not you who imagine things.

00:00:17A new study tries to show that synesthesia is very real,

00:00:21and brain scanners prove it.

00:00:23When these synesthetic people hear colors,

00:00:26the scanners reveal that the parts of their brain linked to sight and sound communicate with each other.

00:00:32Since synesthesia seems to be of a genetic nature,

00:00:36some researchers have chosen three families where this characteristic was present.

00:00:41They then played with DNA sequencing

00:00:44and compared the genes of synesthetic members of the same family to those that were deprived of it.

00:00:49They still haven't completely confirmed this unique characteristic,

00:00:53but they managed to restrict it to as few as 37 possible genes.

00:00:58Sometimes, after a nap in an uncomfortable position,

00:01:01you may have felt tingling or a tingling in your arm or leg.

00:01:06You might think it has everything to do with poor blood circulation.

00:01:10But in fact, it could be due to a little thing called paresthesia.

00:01:15It's when your body starts to feel unusual sensations

00:01:19because your nerves are compressed or irritated.

00:01:22Paresthesia can give you anything,

00:01:25from a burning sensation to this annoying sensation that your arm or leg no longer responds to at all.

00:01:30It could even add discomfort or these good old characteristic tingling.

00:01:35Normally, it shouldn't take you more than 30 minutes.

00:01:39Shake the affected part of the body vigorously, and it could speed up the process.

00:01:44If it lasts longer, or if you have repeated episodes of paresthesia for no apparent reason,

00:01:50it is preferable to consult a specialist to make sure everything is fine.

00:01:55Do you know what is also worth checking?

00:01:58If you have already given a blue thumb to this video,

00:02:01and if you are subscribed to the channel.

00:02:03You know, just to be sure not to miss anything.

00:02:07In normal times, you never think about your stomach or all the chemistry it contains.

00:02:13Can you imagine if one day this substance simply disappeared?

00:02:17It contains chlorhydric acid, which is also used in fertilizers, rubber and steel.

00:02:24If you inhale it, you will have serious breathing problems and in your nose.

00:02:29Every time you chew something, your stomach begins to produce these gastric juices.

00:02:34They are useful because they can break down proteins, activate pepsin,

00:02:38eliminate all the bacteria that you have been able to swallow without even knowing it,

00:02:42and tell your food to go, well, out.

00:02:48Without this acid, the food would stay right there,

00:02:51turning into a breeding ground for bacteria.

00:02:55Proteins and nutrients would not be absorbed by it.

00:02:58Your lunch could quickly go through your digestive system,

00:03:03and you would end up expelling undigested food.

00:03:08There is a reason why paper cuttings hurt so much.

00:03:12To begin with, they occur on the tip of your fingers, which are very sensitive areas.

00:03:18It is because they are full of receptors, which are like the receptionists of your body,

00:03:22helping you determine the size, shape, texture and temperature of the things you touch.

00:03:29When you cut yourself with paper, these receptors are instantly solicited,

00:03:34sending unpleasant information to the brain.

00:03:37Paper cuttings do not look like a sharp cut made with a sharp knife either,

00:03:42because of the foam on the edges of the sheet.

00:03:45This exposes your receptors even more.

00:03:48Paper cuttings do not bleed much and do not coagulate well either,

00:03:52which leaves the nerves alive and aggravates the discomfort even more.

00:03:57We always use our hands, so these cuts continue to reopen,

00:04:01taking an infinite amount of time to heal.

00:04:04Paper is often treated with chemicals that can irritate your skin.

00:04:10The déjà vu seems to strike from nowhere.

00:04:13You are not a wizard, and you do not communicate with the spirits of the beyond either.

00:04:18It is simply your brain that works badly.

00:04:22According to doctors, the déjà vu occurs when two parts of the brain have a little trouble understanding each other.

00:04:28These two parts are located on each side of your skull, just above your temples.

00:04:33They are a bit like the memory cards of your brain,

00:04:36and help you remember certain things, such as places or the face of other people.

00:04:42They even disconnect emotions and are in charge of language.

00:04:46Now, in each of these areas of the brain, which are called temporal lobes,

00:04:51there is a region called the hippocampus.

00:04:53It is responsible for short-term memory.

00:04:56Sometimes, the brain can encounter small malfunctions, confusing the hippocampus.

00:05:01It is then that we feel the déjà vu.

00:05:04This whole process disturbs your memory of recognition,

00:05:08giving you this strange feeling that you have already been there before,

00:05:12or that you have already met a person you see for the very first time.

00:05:17It is a completely normal process,

00:05:19and you are more likely to experience déjà vu if you are between 15 and 25 years old.

00:05:25It also seems that people who travel a lot,

00:05:28or have the ability to remember their dreams, experience it more often.

00:05:34It is difficult to imagine that an entire civilization can survive without anyone being able to see.

00:05:41This seems highly improbable, and here is why.

00:05:45First, imagine trying to cultivate crops without even being able to see what you are doing.

00:05:51The preparation of the soil would become a nightmare,

00:05:54because, without sight, we would get lost in the first field of wheat,

00:05:58without any reference point.

00:06:00Harvesting just a little of this food would not be an easy thing either.

00:06:04Animals could be hiding everywhere, ready to harm us.

00:06:08Communication would be as complicated,

00:06:11because we would not be able to read something without touching it.

00:06:15Even our social lives would be different.

00:06:18Without sight, we should trust our voices.

00:06:21Trusting someone without knowing who else is listening,

00:06:24thank you.

00:06:26If you have ever eaten a very spicy pepper,

00:06:29you know that it is not technically hot.

00:06:31In terms of temperature,

00:06:33then why do we feel like it is burning us,

00:06:36even if it has just come out of the refrigerator?

00:06:39Well, spicy foods contain chemical compounds

00:06:43that deceive our body so that it alters its internal thermostat.

00:06:47First, our lips and tongue feel like they are on fire.

00:06:51Then, our nose starts to run,

00:06:54and we can even shed a tear, or two.

00:06:57The blood vessels dilate,

00:06:59and suddenly, our body temperature increases.

00:07:02To cool things down, we start to sweat.

00:07:06Our lungs can also participate

00:07:08and signal to our diaphragm to produce hocks,

00:07:11in order to chase this irritating intruder.

00:07:15In most cases,

00:07:17all these bodily triggers are caused by a substance called capsaicin,

00:07:21often found in strong peppers like habanero and cayenne pepper.

00:07:26Even if we sometimes feel like moving while we are dreaming,

00:07:30this is not the case thanks to a complex system in our body.

00:07:34This one prevents our muscles from doing all kinds of extravagant things

00:07:38related to crazy stories that our brain could invent during the night.

00:07:42It turns out that most of this brain chemistry

00:07:45occurs during the paradoxal sleep phase, or REM,

00:07:48about 90 minutes after you fall asleep.

00:07:52During this phase,

00:07:54your brain experiences some of the strangest dreams,

00:07:57while your voluntary muscles,

00:07:59like your arms and legs, are deactivated.

00:08:02This muscular blockage is the reason why some people wake up

00:08:06and cannot move,

00:08:08experiencing what is called sleep paralysis.

00:08:11The big mystery was to know how the muscles got into this state of paralysis.

00:08:16At first, researchers thought that glycine, a neurotransmitter,

00:08:20was responsible for it.

00:08:22Research has shown that even if we block the production of glycine,

00:08:26the muscles remain frozen.

00:08:29It took a little more time for scientists to discover

00:08:32that in order to maintain these immobile muscles,

00:08:35you need both glycine

00:08:37and another chemical substance of communication,

00:08:40called GABA.

00:08:42We are not as hairy as our ancestors,

00:08:45but we still have the skin of a hen when we are cold.

00:08:48It is because of these little muscles in our hair follicles,

00:08:51called hair erector muscles,

00:08:54that pull them up.

00:08:56For furry animals,

00:08:58this feature helps them stay warm,

00:09:00but for us, it does not accomplish much in terms of heat.

00:09:04However, we and a few other less hairy creatures

00:09:07have maintained this ability over the years.

00:09:10Experiments have been carried out to find out more about this hen's skin.

00:09:14We found three key actors,

00:09:16these hair erector muscles,

00:09:18sympathetic nerves and hair follicles.

00:09:21When we tried to influence the nerves,

00:09:23the growth of the hair slowed down.

00:09:26These nerves and our hair follicles work together,

00:09:29creating chemical synapses.

00:09:32Thus, hen's skin is not only a quick solution

00:09:35to overcome a low temperature.

00:09:38It could also communicate to our stem cells

00:09:41to grow more hair in the long run.

00:09:44This is why the loss of these muscle cells

00:09:46could be linked to baldness.

00:09:50I have drawn up a list of the most frightening abandoned sites in the world.

00:09:54There is everything,

00:09:55ghost skyscrapers in the old amusement park.

00:09:58Shall we go for a ride?

00:10:00If you have seen Martin Scorsese's Shooter Island,

00:10:03you know that some islands can be extremely sinister.

00:10:06Even if this abandoned place looks like the setting of a horror movie,

00:10:09it is a little more real.

00:10:12The island of Hashima is located 15 km from the city of Nagasaki.

00:10:16It has been abandoned for nearly 50 years.

00:10:19You see, when we leave unoccupied buildings

00:10:21and without surveillance in deserted areas for a while,

00:10:24nature usually takes over.

00:10:27Judging by its current appearance,

00:10:29I would never have guessed that the island of Hashima

00:10:31was once an important coal extraction zone.

00:10:35All the coal extracted from the region

00:10:37was shipped to the rest of the country

00:10:39to feed its rapid industrialization.

00:10:42But mineral resources are limited, we know.

00:10:45Thus, when coal reserves began to decrease,

00:10:49people had little more to do in the region.

00:10:53Which brings us back to today.

00:10:55If you feel adventurous,

00:10:57you can take a boat tour of Nagasaki on the island of Hashima

00:11:00and discover this dystopian science fiction city.

00:11:03You will see empty buildings,

00:11:05invaded by vegetation,

00:11:07and you will be kept away from buildings that could collapse.

00:11:10An excellent idea for a Sunday, isn't it?

00:11:14This is what I call

00:11:16Disney,

00:11:17but with a dark touch.

00:11:19In 2014, a group of promoters said

00:11:22that it would be a good idea to build

00:11:24a luxurious castle city like Disney

00:11:26in the middle of a Turkish forest.

00:11:29They aimed at the rich Europeans,

00:11:31with sums ranging from 370 to 500,000 euros,

00:11:35to invest in their crazy business.

00:11:40As the city was built near a city known for its hot springs,

00:11:44the owners of these luxurious villas

00:11:46would even have their own jacuzzi.

00:11:50The problem is that people didn't like the idea.

00:11:53Some began to complain that the architecture

00:11:55was too far from the Ottoman style of the region,

00:11:58and others thought that too many trees had been cut

00:12:00to build this fairy tale city.

00:12:02In the end,

00:12:03the promoters have accumulated so many fines

00:12:05that they had to declare bankruptcy

00:12:07and the project was abandoned.

00:12:09They didn't demolish the castles, though.

00:12:11So now it all looks like a Disney movie,

00:12:14a little sinister.

00:12:18The skyscrapers are fine,

00:12:20but have you ever seen the world's biggest ghost skyscraper?

00:12:23The Golden Finance 117

00:12:25was supposed to be the masterpiece

00:12:27of the Golden Metropolitan Scheme,

00:12:29a tentacular artificial city

00:12:31belonging to the billionaire Pan Sutong.

00:12:34This mini-city was to be a residential and commercial center

00:12:37just a few minutes from the city center of Tianjin.

00:12:42It was to be made up of French and Italian-style manors,

00:12:46a polo club,

00:12:47and even a wine museum.

00:12:49The promoters had the intention of attracting the super-rich.

00:12:52The 128-story building

00:12:54was considered the jewel of the mini-city.

00:12:57And I mean literally,

00:12:59the top of the building was supposed to be the shape of a diamond.

00:13:02Construction began in 2008,

00:13:05and it's still not finished.

00:13:07The overall project was estimated at 10 billion US dollars.

00:13:11But due to several unfortunate events,

00:13:14it has never been fully realized.

00:13:16Some say that all this was probably doomed to failure from the start.

00:13:20Because people who could afford to live in such a place

00:13:23did not want to live in a second-rate industrial city.

00:13:27And as you may remember,

00:13:29there was a great economic recession in 2008.

00:13:32It really slowed things down.

00:13:35Despite everything, this ghost skyscraper

00:13:37was the fifth tallest building in the world at the time.

00:13:41If you had to choose three synonymous words of utopia,

00:13:44which would you choose?

00:13:45I would say, for example, happiness, peace and abundance.

00:13:48This city, supposed to be utopian,

00:13:50could not be further from these qualities.

00:13:53Welcome to the Mojave Desert,

00:13:55in California.

00:13:57Do you see the city square on the sandy ground?

00:14:00These lines are the remains of a project

00:14:02that never reached its final stage.

00:14:05This city was supposed to be called California City.

00:14:09This utopian city was imagined by Nat Mendelsohn,

00:14:13a university professor who studied urbanism a lot.

00:14:16The project began in the late 1950s

00:14:19when he bought more than 32,000 hectares of land in the desert.

00:14:23He wanted to create a place where families would flourish.

00:14:26At the time, housing was affordable,

00:14:28and the city was equipped with leisure options

00:14:30such as a golf course, a pool and playgrounds.

00:14:34People started buying land,

00:14:37but the project was interrupted.

00:14:40So, if you get out of Los Angeles by car,

00:14:43you may see a small hill of houses,

00:14:45a tiny part of what California City was supposed to become.

00:14:50According to you, which European country is full of abandoned places?

00:14:54If you answered Spain, then bravo!

00:14:57Here are a few.

00:14:59What was once planned to be a center of luxury villas

00:15:02is now a graffiti havoc.

00:15:05The place began to be built in 1969,

00:15:08but only a year later, the work was abandoned.

00:15:11You can also find the Festival Club in Ibiza.

00:15:14You see, Ibiza has not always been a party place.

00:15:17This club opened its doors in 1972,

00:15:20but two years later, Spain experienced a major oil crisis,

00:15:24and fewer and fewer tourists went to visit the island.

00:15:27The club ended up being abandoned,

00:15:29and today, we mainly come here to admire the graffiti.

00:15:33The exterior of the houses is in perfect condition.

00:15:36It is difficult to believe that they are actually abandoned.

00:15:39According to the explorer who found them,

00:15:41they would have been delivered to this sad fate in 2008.

00:15:45Once again, this terrible year of economic recession.

00:15:48The company that built them went bankrupt

00:15:51during the last quarter of the construction,

00:15:53and had to abandon the project at its very last stage.

00:15:56What a sad end.

00:15:59In Miami Beach, you will find a luxurious abandoned hotel

00:16:02that once hosted a Beatles concert.

00:16:05At the end of the 1950s,

00:16:07it was the favorite place of celebrities like Frank Sinatra.

00:16:11Today, the Oville complex has been demolished.

00:16:14It was closed in 2007,

00:16:16after a fire damaged certain structures of the building.

00:16:20For a while, they decided to leave the hotel as it was,

00:16:24with its furniture and memories still inside.

00:16:27Let's see what it looked like.

00:16:30The main entrance and the hall

00:16:32It was a beautiful 50s style ambiance.

00:16:35The kitchen was still equipped with dishes and cutlery,

00:16:38the bathroom had cabins and hair dryers,

00:16:41and electronic keys, I dig the floor, everywhere.

00:16:45It was in the big ballroom of the hotel that magic operated.

00:16:48In 1964, the Beatles gave a concert there

00:16:51during which thousands of fans without tickets

00:16:53waited outside, hoping to see the stars.

00:16:57The Oville may have played an important role

00:16:59in American cultural history.

00:17:01But today, it's just an abandoned site.

00:17:06There is no doubt that some of the most interesting abandoned places in the world

00:17:10are old amusement parks.

00:17:13Amusement parks are usually full of laughter and happy moments.

00:17:17But not those.

00:17:19The Nara Dreamland was supposed to be the Disney World of Japan,

00:17:22but the project failed.

00:17:25Today, it's just a dream.

00:17:28If you had visited it before its demolition,

00:17:31this is what you would have seen.

00:17:33Your heart was beating faster than usual

00:17:35when you passed in front of these Russian mountains covered with fog.

00:17:38Was it supposed to be the Servin?

00:17:40And yes.

00:17:41Everyone in this place was shouting,

00:17:43get out of here!

00:17:44But we are curious.

00:17:46The ground of the park,

00:17:48billiard balls and disfigured stuffed animals.

00:17:51Want to enter an empty restaurant?

00:17:53It's weird how the tables and stools were left in their place.

00:17:57In what used to be a souvenir shop,

00:17:59there were empty shelves and an old ticket dispenser.

00:18:03So, you too, all this troubled you.

00:18:05What a fright!

00:18:09The pilots are not allowed to take identical meals when they work.

00:18:12Imagine that you are on a trans-oceanic flight,

00:18:14the plane flies over the Pacific Ocean.

00:18:16The air hostesses distribute the meals of the evening.

00:18:19Everyone enjoys the pasta.

00:18:21But the sauce tastes a little weird.

00:18:24It's probably normal.

00:18:26After all, we eat a plane meal.

00:18:28It can't taste like a star restaurant, can it?

00:18:32Time passes.

00:18:34Oh no!

00:18:35You were right.

00:18:36There was indeed a problem with the food.

00:18:39But if all passengers have the same problem,

00:18:41so do the pilots.

00:18:43To prevent that they are both sick,

00:18:45the pilots are advised not to take the same meal at the same time.

00:18:49So, if one pilot feels bad,

00:18:51the other can take over.

00:18:54This is not an imperative rule

00:18:56announced by the official aviation agencies.

00:18:58But most airlines establish their own rules in this regard.

00:19:02It makes sense.

00:19:04The on-board agents have access to hidden equipment such as a defibrillator,

00:19:08additional oxygen, an extractor and an adhesive tape.

00:19:11But the most interesting equipment they have

00:19:13are undoubtedly the handcuffs.

00:19:15These objects are there to protect the passengers,

00:19:18others and sometimes themselves.

00:19:20In fact, the crew members have everything they need

00:19:23to neutralize a possible troublemaker.

00:19:25The aviator sunglasses look cool on the pilots in the movies.

00:19:29But in real life, they don't wear polarized glasses.

00:19:32First of all, they have an anti-blinding effect.

00:19:35This can cause some problems in the cockpit.

00:19:37A pilot must be able to read the instruments.

00:19:39But cockpit equipment, such as LCD screens,

00:19:41emit a polarized light.

00:19:43A pilot wearing these glasses

00:19:45will therefore not be able to read the screens

00:19:47with 100% efficiency.

00:19:50For safety reasons,

00:19:52pilots must not wear sunglasses.

00:19:54Let's imagine a dazzling reflection

00:19:56coming from the windshield of another plane.

00:19:58But the pilot missed the mark

00:20:00because of his tinted glasses. Ouch!

00:20:02Have you ever noticed a hole in the tail of a plane?

00:20:05Well, most commercial planes have one.

00:20:08The next time you get on a plane,

00:20:10look closer.

00:20:11The hole has a fanciful name,

00:20:13the auxiliary power group.

00:20:15From the outside, it looks like a hole.

00:20:17But it's actually a hidden turbine engine.

00:20:19Most of the time,

00:20:21the auxiliary power group stays off during the entire flight.

00:20:23It starts to work when the plane lands.

00:20:25It powers the cabin lights,

00:20:27the air conditioning,

00:20:28and all the cockpit electronics.

00:20:30But don't underestimate the auxiliary power group's performance.

00:20:32It can also provide the power

00:20:34needed to start the main engines.

00:20:37You just watched a nice video

00:20:39and you learned what the auxiliary power group means.

00:20:41A perfect way to start a conversation in the evening.

00:20:44Unfortunately, you're not in a good mood.

00:20:46You just want to take the plane, land,

00:20:48and start your holidays.

00:20:49But you're not lucky.

00:20:50There's only one door to board.

00:20:52And you're in a queue.

00:20:54Why do planes always have several doors?

00:20:57According to experts,

00:20:58the main problem is that the runway takes up a lot of space.

00:21:01When a plane is loaded from the front and from the back,

00:21:04it occupies two runways,

00:21:06which is not ideal for the operators.

00:21:09Recently renovated or built airports

00:21:11tend to have a double boarding

00:21:13compared to former terminals.

00:21:16Change of scenery.

00:21:17Let's jump in a cruise ship.

00:21:19There are hidden passages and secret doors in these ships.

00:21:23These are the secrets of the initiator.

00:21:25The ship's crew works most often in their reserved area.

00:21:29How can an employee go from one place to another

00:21:32without using the stairs and doors used by the passengers?

00:21:35Well, there is a network of corridors and stairs

00:21:38all around the ship used only by the crew.

00:21:41I'm serious when I talk about secret doors.

00:21:43They get confused with the walls.

00:21:45They pass unnoticed for those who don't know where the door is.

00:21:48Maybe you can accidentally fall on it.

00:21:51Here's a clue.

00:21:52Watch out for the walls near the customers' stairs.

00:21:54They are in the corner.

00:21:56These gigantic cruise ships

00:21:58are actually floating metal objects.

00:22:00This leads me to a funny anecdote about cruise cabins.

00:22:03The walls of the cruise ship cabin are magnetic.

00:22:05Let's imagine you're on a cruise for a month

00:22:07across several countries.

00:22:08You collect magnets on the theme of the destination

00:22:11and you decorate your cabin.

00:22:12True cruise enthusiasts know the magic of magnets.

00:22:16They put some magnetic hooks in their luggage.

00:22:19Use the magnetic hooks to add additional storage in your cabin.

00:22:24Hang clothes, accessories, postcards or hats.

00:22:27Whatever you want.

00:22:28Let's talk about ships again.

00:22:30Why do some ships and boats have small holes

00:22:32that let the water escape permanently

00:22:34to keep the hull dry?

00:22:36Water accumulates over time in the hull

00:22:39and the pump of the hull evacuates it automatically.

00:22:42Ships don't have headlights.

00:22:44The use of a headlight could prevent accidents, right?

00:22:47If it works for cars, why not for ships?

00:22:49Headlights are the source of light.

00:22:51But the light that comes out of them

00:22:53bounces on the light source at some point.

00:22:55With cars, for example,

00:22:57the headlights work because the area to be lit is narrow

00:23:00and you can easily intervene if you see an obstacle on the road.

00:23:03For boats, it's extremely complicated.

00:23:06The light source must be powerful enough

00:23:09to illuminate the area the captain wants to monitor.

00:23:11Big cargo ships, for example,

00:23:13need more than a kilometre to stop or make decisions.

00:23:16In addition, you have to imagine

00:23:18how intense the light of the ship must be

00:23:20to illuminate the entire area in front of it.

00:23:22Ships are spotted using different types of lights

00:23:25called navigation lights.

00:23:27They are small but practical.

00:23:30They are arranged in a standardized way

00:23:32so that boats can spot each other.

00:23:35What's fascinating is that they're not only used

00:23:37to spot each other in the dark.

00:23:38They also indicate the movements

00:23:40and directions of other ships.

00:23:42Here's an example.

00:23:44Imagine a boat equipped with two navigation lights.

00:23:46The front one is lower, near the deck of the ship.

00:23:49The other one, at the back, is higher.

00:23:51This means that the boat is going to the right.

00:23:53It can safely pass next to the others

00:23:55without bumping into them.

00:23:57Trains don't have seatbelts.

00:23:59It's a bit weird, isn't it?

00:24:02Every time there's a train-related accident,

00:24:04this question comes up.

00:24:06Almost everywhere in the world,

00:24:08there are no seatbelts in trains.

00:24:10Several studies have been carried out on this subject.

00:24:12Some of them have created accident simulations.

00:24:14And the results were surprising.

00:24:16The use of seatbelts in a train

00:24:18could potentially increase the number of injuries.

00:24:21In cars, seatbelts are very effective

00:24:23in protecting the passenger

00:24:25and are systematically used.

00:24:27The logic behind the seatbelt

00:24:29is to protect the person

00:24:31when a collision causes a rapid deceleration.

00:24:33But trains have such momentum

00:24:36In a plane, passengers use seatbelts

00:24:38when taking off, landing

00:24:40and in case of turbulence.

00:24:42This is not the case for trains.

00:24:44Entering and leaving a station

00:24:46does not pose a high risk.

00:24:48Experts believe that the driver's concentration

00:24:50and regular maintenance

00:24:52are the best ways to strengthen railway safety.

00:24:54Now, you're travelling by train.

00:24:56You look out the window.

00:24:58There are small stones along the railway

00:25:00to accompany you on your journey.

00:25:02These stones are officially called

00:25:05They play a very important role.

00:25:07They support and maintain the railway.

00:25:09But they are not there by mere coincidence.

00:25:11Now, look at the stones up close.

00:25:13You can see that there is not one

00:25:15well carved on the tracks.

00:25:17These are not ordinary stones

00:25:19arranged randomly on the tracks.

00:25:21Each rock has sharp and abrupt edges.

00:25:23These edges cling to each other.

00:25:25They protect the railway

00:25:27from violent collisions.

00:25:29They facilitate the flow of water

00:25:31in case of heavy rain

00:25:34Now, let's imagine that

00:25:36we replace them with round stones.

00:25:38They will slide down.

00:25:40Finally, the ballast will collapse

00:25:42and the tracks will collapse.

00:25:44This is the last thing we want,

00:25:46especially if we are a passenger on this train,

00:25:48isn't it?

00:25:50Let's discover some impressive facts

00:25:52about poisons.

00:25:54No, this is not an Nth video

00:25:56with the top 10 most venomous animals.

00:25:58We will mention several here,

00:26:00but this is not where we want to go.

00:26:03There are two glasses in front of you.

00:26:05The first is filled with calcined milk

00:26:07and the other contains the venom

00:26:09of one of the most dangerous snakes in the world,

00:26:11the Aspic viper.

00:26:13According to you,

00:26:15what is the liquid

00:26:17that could have the worst consequences

00:26:19on your health?

00:26:21The right answer is calcined milk.

00:26:23It can cause bloating, indigestion

00:26:25and stomach burns.

00:26:27But if you drink the venom of this snake,

00:26:29nothing will happen.

00:26:31This substance is a particular type of protein

00:26:33and the gastric juices

00:26:35decompose from it like any other food.

00:26:37The toxin contained in the poison

00:26:39is only dangerous in contact with blood.

00:26:41So if you have an injury

00:26:43in your mouth or stomach,

00:26:45then you will have problems.

00:26:47But as long as the toxin remains

00:26:49out of your blood circulation system,

00:26:51you don't have to worry

00:26:53excessively.

00:26:55However, it doesn't always work like that.

00:26:57Some animals secrete a poison

00:26:59that penetrates your body

00:27:01at the slightest physical contact.

00:27:03But venomous creatures must deliver

00:27:05this dangerous substance

00:27:07inside your blood.

00:27:09This is the difference between poison and venom.

00:27:11In the first case,

00:27:13these are animals that can poison you

00:27:15in a passive way,

00:27:17if you touch them for example.

00:27:19They don't make any effort

00:27:21and the poison is constantly released

00:27:23by their body.

00:27:25The venomous androbat frog

00:27:27But everyone is afraid to touch it

00:27:29because its skin secretes

00:27:31one of the most dangerous poisons on Earth.

00:27:33The toxic particles contained

00:27:35in the poison of these batrachians

00:27:37are so tiny that they easily pass

00:27:39through the pores of your skin

00:27:41and cause a violent reaction in your body.

00:27:43But the toxic particles

00:27:45of venomous animals are bigger

00:27:47and can only penetrate your body

00:27:49by injection.

00:27:51These creatures bite and sting

00:27:53to deliver the venom into the blood.

00:27:55Venomous snakes, geese, spiders

00:27:57and other creatures

00:27:59use their venom to attack their prey.

00:28:01Frogs or venomous fish

00:28:03covered with a poisoned skin

00:28:05use these toxins

00:28:07to defend themselves.

00:28:09This is the difference.

00:28:11One of the most venomous creatures

00:28:13in the world is the jellyfish.

00:28:15When it stings, it injects

00:28:17a powerful toxin into its enemy

00:28:19affecting the nervous system

00:28:21and the skin cells.

00:28:23This toxin is harmful

00:28:25not only for marine creatures

00:28:27but also for humans.

00:28:29This toxin acts quickly

00:28:31and can cause serious health problems

00:28:33in a few minutes.

00:28:35One of the most toxic creatures

00:28:37in the world,

00:28:39besides the androbat frog

00:28:41is the jellyfish.

00:28:43Yes, the famous Japanese jellyfish.

00:28:45Many have probably heard

00:28:47that if the cook prepared

00:28:49this fish in an incorrect way

00:28:51this fish is a thousand times more powerful

00:28:53than cyanide.

00:28:55And the amount of poison contained

00:28:57in a single jellyfish

00:28:59is enough to harm

00:29:01several dozen people.

00:29:03When the fish is in danger

00:29:05it swallows air and water

00:29:07and increases in volume.

00:29:09In this state, these thorns

00:29:11containing the toxin

00:29:13become even more dangerous.

00:29:15So never touch this fish

00:29:17if you see it in the sea.

00:29:19The jellyfish

00:29:21is a species

00:29:23of intraspecific competition.

00:29:25It is found in venomous mammals

00:29:27such as the Australian ornithorynch.

00:29:29There are small ergos in their legs

00:29:31that secrete the toxin.

00:29:33An ornithorynch can paralyze

00:29:35an opponent with a single kick.

00:29:37But these animals also use their poison

00:29:39during the competition

00:29:41they have before reproduction.

00:29:43Their bodies strengthen

00:29:45their toxic properties

00:29:47to weaken each other.

00:29:49The one whose poison is the most effective

00:29:51then wins the battle.

00:29:53Some animals have to be bitten and stung

00:29:55to use their venom

00:29:57while others just wait to be touched

00:29:59by someone else.

00:30:01But what about this little creature

00:30:03that releases its poison with an arrow?

00:30:05Here is the ornithorynch.

00:30:07It hides inside its house

00:30:09and waits for a small fish to swim closer.

00:30:11Then it releases

00:30:13a toxic harpoon from its trunk

00:30:15to paralyze the unfortunate fish.

00:30:17Then the ornithorynch swallows

00:30:19its entire prey like an anaconda.

00:30:21The venom of this little animal

00:30:23is also dangerous for humans

00:30:25because it causes serious respiratory

00:30:27disorders, vision,

00:30:29as well as many other problems.

00:30:31On the other hand, the substance contained

00:30:33in the poison of the ornithorynch

00:30:35is used in medicine to make

00:30:37a powerful analgesic.

00:30:39And this is not the only case

00:30:41of an ornithorynch used in medicine.

00:30:43The ornithorynch,

00:30:45in the name of Gila's monster,

00:30:47releases a neurotoxin

00:30:49produced by its salivary glands

00:30:51when it dies.

00:30:53Because of this venom,

00:30:55the bite of this animal

00:30:57is considered one of the most painful

00:30:59in the world.

00:31:01People who have been attacked

00:31:03by a Gila's monster

00:31:05are said to have felt a sensation

00:31:07comparable to lava

00:31:09melting in their veins.

00:31:11Some poisons cause muscle paralysis.

00:31:13Others can cause respiratory

00:31:15problems.

00:31:17And others even increase

00:31:19blood pressure.

00:31:21But why are they all different?

00:31:23All these variations depend

00:31:25on the prey hunted by venomous animals.

00:31:27For example, most vipers

00:31:29feed on small mammals

00:31:31with rapid metabolism.

00:31:33As a result, reptiles have

00:31:35developed a venom that disturbs

00:31:37the coagulation of blood,

00:31:39resulting in a rapid loss of body control

00:31:41for a hare in the race.

00:31:43However, for animals

00:31:45with cold blood,

00:31:47such a strategy would be much less effective.

00:31:49This is why some types of

00:31:51cobras produce a neurotoxic

00:31:53venom that can disturb

00:31:55the transmission inside the nervous system.

00:31:57Such a substance

00:31:59effectively hits the organisms

00:32:01of cold-blooded creatures.

00:32:03All this suggests that venomous

00:32:05and toxic creatures adapt

00:32:07their toxins according to their habitat.

00:32:09This is why the venoms

00:32:11of the same species can vary so much.

00:32:13If a viper

00:32:15bites you in a certain region,

00:32:17an antidote from another region

00:32:19could be of no use to you.

00:32:21In places where survival conditions

00:32:23are more arduous, snakes can

00:32:25develop a more dangerous venom

00:32:27to repel enemy attacks

00:32:29or catch fast prey.

00:32:31But this principle also works

00:32:33in the other direction.

00:32:35A group of snakes in an environment

00:32:37where they can easily catch food

00:32:39and not defend themselves against other animals.

00:32:41This type of snake

00:32:43can eventually become non-venomous.

00:32:45This is because the production of venom

00:32:47is a complex process

00:32:49that requires a lot of energy

00:32:51and resources of the organism.

00:32:53And if the conditions do not require

00:32:55the use of such a substance,

00:32:57then the snakes will stop producing it.

00:32:59This happened with sea snakes.

00:33:01They are some of the most

00:33:03venomous animals on earth

00:33:05who hunt fish in the ocean.

00:33:07As their prey was much faster

00:33:09than them, they had to develop

00:33:11a powerful venom that would paralyze

00:33:13the fish quickly.

00:33:15But a species of sea snake

00:33:17stopped feeding in this way.

00:33:19Instead of hunting fish,

00:33:21they started eating their eggs.

00:33:23This prey does not run away,

00:33:25so that the snakes no longer need venom.

00:33:27After all, they stopped producing it.

00:33:29How many animals on earth

00:33:31can be venomous or toxic?

00:33:33According to the calculations of scientists,

00:33:35about 15 to 20%.

00:33:37But it is likely that this figure

00:33:39is much higher,

00:33:41because we have not fully studied

00:33:43all the biodiversity of our planet.

00:33:45Interestingly,

00:33:47almost all species of animals

00:33:49have a venomous or toxic parent.

00:33:51Even among mammals,

00:33:53the ornithorynchus is not the only

00:33:55venomous creature.

00:33:57The lorillant seems to be an animal

00:33:59that is highly offensive.

00:34:01And yet, this primate from Southeast Asia

00:34:03injects venom with its teeth

00:34:05during a bite.

00:34:07In addition, some species of sea snake

00:34:09produce venom in the same way

00:34:11to paralyze their prey.

00:34:13And vampire bats are the only

00:34:15venomous flying mammals in the world.

00:34:17Okay, we have seen a large number

00:34:19of venomous and toxic animals today.

00:34:21But what were they in the past?

00:34:23Many scientists think

00:34:25that venomous dinosaurs

00:34:27existed millions of years ago.

00:34:29Some studies tend to confirm this hypothesis.

00:34:31Glands and venomous tissues

00:34:33of these formidable reptiles

00:34:35have not survived to this day.

00:34:37But,

00:34:39in the teeth of some dinosaurs,

00:34:41scientists have found

00:34:43small cracks that modern

00:34:45venomous snakes and lizards

00:34:47also present.

00:34:49It is therefore possible that Jurassic monsters

00:34:51used these holes

00:34:53through which they secreted their venom.

00:34:55Landing gear tires

00:34:57do not burst

00:34:59because they are designed for a load

00:35:014 to 5 times higher than those

00:35:03they undergo during landing.

00:35:05The wheel itself can break,

00:35:07but the tire does not burst.

00:35:09This little trick based on behavioral psychology

00:35:11can help you choose the fastest line

00:35:13at the airport.

00:35:15If there are several lines to register,

00:35:17choose the one on the left.

00:35:19You should get to the counter faster

00:35:21this way.

00:35:23Your skin usually becomes a little dry

00:35:25during the flight.

00:35:27This is due to the low humidity

00:35:29in the cabin.

00:35:31Bring a good moisturizing cream

00:35:33with you to keep your skin hydrated on board.

00:35:35Did you know that the pilot

00:35:37and co-pilot of an airplane

00:35:39always eat different meals

00:35:41before a flight?

00:35:43In this way,

00:35:45if one of them has a food poisoning,

00:35:47the other will be able to take control

00:35:49of the aircraft.

00:35:51Airplane tablets

00:35:53are one of the dirtiest surfaces in the cabin.

00:35:55So make sure you wash your hands frequently

00:35:57and clean the tablet

00:35:59with an antibacterial cloth

00:36:01to get rid of all the bacteria

00:36:03that are piling up.

00:36:05If you are sitting on a seat next to the hallway,

00:36:07you can have more space to stretch your legs.

00:36:09Just press the button

00:36:11located under the armrest

00:36:13on the outside.

00:36:15This will raise the armrest,

00:36:17giving you more space for your legs

00:36:19to sink into your ribs.

00:36:21This is one of the reasons

00:36:23why the light in the cabin is dim.

00:36:25Passengers must get used to the darkness

00:36:27in case of an emergency landing

00:36:29at night.

00:36:31In this way,

00:36:33their eyes will already be used to the absence of light,

00:36:35which will facilitate the evacuation.

00:36:37The flight attendants ask you

00:36:39to lift the windows

00:36:41so they can see what's going on outside.

00:36:43This way, they can choose the best way

00:36:45to evacuate passengers in case of emergency.

00:36:47Almost all airliners are white,

00:36:49because this color best reflects the sun's rays

00:36:51and prevents the plane from overheating.

00:36:53Another good reason

00:36:55is that white paint is cheaper.

00:36:57In addition, workers and engineers

00:36:59can easily notice

00:37:01any damage on a white surface.

00:37:03It is preferable to avoid

00:37:05making important decisions during a flight.

00:37:07Your brain does not receive enough oxygen

00:37:09at such a height

00:37:11and this negatively affects its functioning.

00:37:13Chewing gum,

00:37:15the hard candies and the mint candies

00:37:17can help you avoid having your ears

00:37:19clogged during take-off and landing.

00:37:21It is not thanks to the candies themselves,

00:37:23but thanks to the swallowing process.

00:37:25Swallowing also helps.

00:37:27As for chewing gum,

00:37:29it also helps to get rid of this bad breath

00:37:31caused by the rarified air at high altitudes

00:37:33which removes the humidity from your body.

00:37:35The dry air

00:37:37can give you the impression

00:37:39that you are getting cold.

00:37:41The cabin air dries your nose and throat

00:37:43if you have the symptoms of a cold.

00:37:45These symptoms usually disappear

00:37:47just after landing.

00:37:49The water used to make coffee

00:37:51and tea on board is not always very clean.

00:37:53Many companies

00:37:55use very good water filters today,

00:37:57but it is better to ask for bottled water

00:37:59if you are thirsty.

00:38:01This little triangle on the plane's wall

00:38:03above your seat

00:38:05means a lot to the flight attendants.

00:38:07These triangles mark the windows

00:38:09through which you can see the flashing lights.

00:38:11They signal the retraction of the landing brakes

00:38:13and the closing of the flaps.

00:38:15Let's say that the pilots discover that there is a problem.

00:38:17In this case,

00:38:19a flight attendant will rush to the window

00:38:21to check what is going on.

00:38:23And for the passengers,

00:38:25it is simply the best place for photos

00:38:27since you can see the wings perfectly.

00:38:29The seats in the middle of the cabin,

00:38:31above the wings,

00:38:33are the best if you have trouble getting around.

00:38:35This area is more balanced

00:38:37and shakes less during turbulence.

00:38:39If you tend to be nervous

00:38:41during the flight,

00:38:43do a little physical exercise

00:38:45just before getting on the plane.

00:38:47A little training session

00:38:49helps to reduce your stress level

00:38:51and makes sure your body releases endorphins,

00:38:53the hormones of happiness.

00:38:55In addition, this physical activity

00:38:57compensates for the hours you spend sitting without moving.

00:38:59The turbines are placed under the wings

00:39:01because it makes the maintenance of the engines

00:39:03less expensive, faster and easier.

00:39:05Previously, they were placed

00:39:07at the level of the tail.

00:39:09This required expensive equipment

00:39:11and a lot more time to repair them.

00:39:13When we started to install the engines

00:39:15under the wings,

00:39:17the price of tickets dropped.

00:39:19Imagine that you are flying in a Montgolfière.

00:39:21You see the burner system

00:39:23installed under the balloon,

00:39:25also called an envelope.

00:39:27It heats the air inside,

00:39:29which makes the Montgolfière go up.

00:39:31Turbulences aboard a plane

00:39:33are this same hot air,

00:39:35but when it gets colder,

00:39:37the plane goes down

00:39:39and the passengers feel like they are doing roller coasters.

00:39:41A hot air current left by another plane

00:39:43can also cause turbulence.

00:39:45This is a common phenomenon on most flights.

00:39:47But generally,

00:39:49the turbulence is so light

00:39:51that passengers do not feel it.

00:39:53Do you know that planes can fly

00:39:55even after a failure of an engine?

00:39:57Pilots can manage such an emergency

00:39:59and land the plane safely.

00:40:01Passengers can feel a slight inclination

00:40:03during the flight,

00:40:05but in most cases,

00:40:07they do not even know that the plane is flying

00:40:09with a single engine.

00:40:11Your eyes receive oxygen directly from the air.

00:40:13It is not driven by blood.

00:40:15Your eyes can be a little dry during the flight,

00:40:17but drops for the eyes in your luggage

00:40:19will help you keep your eyes moist.

00:40:23It is forbidden to carry large volumes of liquid

00:40:25on board,

00:40:27because some dangerous substances

00:40:29can easily be dissolved in water.

00:40:31If a plane has to sink,

00:40:33its wings become lifeboats.

00:40:35Empty fuel tanks also help

00:40:37the planes to float.

00:40:39Moreover, it can take 10 to 60 hours

00:40:41before the plane sinks.

00:40:43It all depends on the model,

00:40:45the weather conditions

00:40:47and the pilot's skills.

00:40:49These smiling air hostesses

00:40:51that you meet when you enter the cabin

00:40:53usually hide their hands behind their backs.

00:40:55They count the people who enter the plane

00:40:57to make sure that all passengers are on board.

00:40:59Despite what people say

00:41:01about the food in the planes,

00:41:03it is actually not so bad.

00:41:05The problem is your sense of taste,

00:41:07which is no longer as efficient

00:41:09because the air in the cabin makes your mouth dry.

00:41:11It also fades your smell.

00:41:13This is why air hostesses

00:41:15add a lot of spices and salt to their meals.

00:41:19Is it true that your hair grows faster during a flight?

00:41:21Not really.

00:41:23Scientists have not been able to prove it.

00:41:25This myth appeared in the first part of the 20th century

00:41:27when some passengers noticed

00:41:29that their beards had grown more during a flight.

00:41:31It is normal for people to have a headache

00:41:33during a flight,

00:41:35especially just after take-off.

00:41:37You climb to a height higher than Mount Everest

00:41:39in the space of about 10 minutes.

00:41:41These changes occur too quickly

00:41:43for your body to adapt.

00:41:47The aircraft's seatbelts

00:41:49are placed above your belly

00:41:51to prevent you from being projected

00:41:53against the ceiling in case of turbulence.

00:41:55As a result,

00:41:57the aircraft starts to move from top to bottom

00:41:59and your seatbelt holds you firmly.

00:42:01Conversely, seatbelts in cars

00:42:03protect people from horizontal collisions.

00:42:07Aircrafts have a special protection

00:42:09against lightning.

00:42:11Even if it strikes,

00:42:13passengers will not feel it.

00:42:15Aircrafts are covered with an aluminum coating

00:42:17that drives the electric current

00:42:19but does not let it penetrate

00:42:21inside the aircraft.

00:42:23It also provides additional protection.

00:42:25Aircraft seats are uncomfortable

00:42:27because airlines

00:42:29try to fit as many passengers

00:42:31as possible in an aircraft.

00:42:33That is why there is so little space

00:42:35between the seats.

00:42:37Two additional rows means

00:42:3912 more passengers.

00:42:41In addition, airlines make lighter

00:42:43aircraft seats to save on fuel costs.

00:42:45Even an additional weight,

00:42:47apparently insignificant,

00:42:49can cost thousands of euros

00:42:51Your seat has a waterproof coating.

00:42:53It is necessary to prevent a fire

00:42:55from spreading in case of an accident.

00:42:57Airport employees

00:42:59transport unrequited luggage

00:43:01to special centers.

00:43:03If the owner does not show up

00:43:05within three months,

00:43:07the luggage is put up for sale

00:43:09in specialized stores.

00:43:11In the past, you could not use

00:43:13your phone in an airplane

00:43:15because mobile phones were dangerous

00:43:17for navigation.

00:43:19Oxygen masks fall

00:43:21not only during strong turbulence

00:43:23but also when the air pressure

00:43:25inside the cabin changes radically.

00:43:27Passengers do not risk anything

00:43:29if they put on their oxygen mask.

00:43:31But in such cases, they are considered

00:43:33as an emergency.

00:43:35And pilots do their best

00:43:37to go down quickly at a safe altitude

00:43:39so that passengers can breathe

00:43:41without oxygen masks.

00:43:43In December 2014,

00:43:45an entire district of Budapest

00:43:47was hit by an ice crystal.

00:43:49The trees in the area could not

00:43:51stand such pressure

00:43:53and began to bend under their weight.

00:43:55It was a frightening phenomenon

00:43:57called the ice fog.

00:43:59When it happens,

00:44:01the temperature drops considerably,

00:44:03freezing everything around,

00:44:05a bit like the detractors

00:44:07in the Harry Potter saga.

00:44:09And all this thanks

00:44:11to a cross temperature chasing.

00:44:13It does not only affect urban furniture

00:44:15but also small ice crystals.

00:44:17When the temperature drops below

00:44:19less than 10°C,

00:44:21droplets of water in the air freeze

00:44:23and turn into crystals.

00:44:25So far, they remain in a liquid state

00:44:27unless they find something to freeze on.

00:44:29Ice fog is generally formed

00:44:31in the coldest regions of the world,

00:44:33such as the Arctic or the Antarctic.

00:44:35Budapest was, at least, unexpected.

00:44:37Hot and humid gases

00:44:39emitted by vehicles and planes

00:44:41can also create thundering fog.

00:44:43A plane takes off on a cold day

00:44:45and bam!

00:44:47It emits so much thundering fog

00:44:49that the next plane can not see anything.

00:44:51This happens sometimes.

00:44:53It is not the same as ice powder,

00:44:55which is when spare crystals

00:44:57fall from a clear sky.

00:44:59They form when there is a lot of humidity,

00:45:01almost 100%,

00:45:03and the air temperature

00:45:05drops well below 0°C.

00:45:07This creates suspended ice crystals

00:45:09in the air that end up

00:45:11in the lungs.

00:45:17There are many other forms

00:45:19of ice as fascinating as

00:45:21the frost flower.

00:45:23It occurs when the air is cold

00:45:25but the ground has not yet completely frozen.

00:45:27The sap inside the plant stems

00:45:29expands when it freezes,

00:45:31which makes them burst.

00:45:33Once this occurs,

00:45:35the liquid flows,

00:45:37meets the frosted air

00:45:39and forms ice crystals.

00:45:41The light of thunderstorms

00:45:43is another strange and unique phenomenon.

00:45:45When a powerful earthquake

00:45:47of magnitude 8.1

00:45:49struck Mexico in 2017,

00:45:51strange images of green and blue

00:45:53light in the sky

00:45:55began to spread on the Internet.

00:45:57These famous Mexican seismic lights

00:45:59only added to the mystery.

00:46:01Just like lightning bolts,

00:46:03thunderstorm lights

00:46:05are quite rare

00:46:07and just as prodigious

00:46:09as difficult to apprehend for scientists.

00:46:11What complicates things

00:46:13is that observations of lights

00:46:15around earthquakes

00:46:17do not all seem to agree.

00:46:19There are many myths and theories

00:46:21about this phenomenon.

00:46:23Lights can decline in many colors

00:46:25and many forms.

00:46:27Studying our past,

00:46:29historians have isolated 65 stories

00:46:31mentioning such apparitions,

00:46:33some of which date back to the 17th century.

00:46:35On November 12, 1988,

00:46:37for example,

00:46:39people reported that a bright purple sphere

00:46:41floated along the St. Lawrence River

00:46:43in Quebec,

00:46:45only 11 days before a powerful earthquake.

00:46:47In Pisco, Peru,

00:46:49the phenomenon took the form of light

00:46:51captured by security cameras in 2007,

00:46:53shortly before an earthquake

00:46:55of magnitude 8.

00:46:57And in 2009,

00:46:59before another earthquake in Italy,

00:47:01in Aquila,

00:47:03the light was only a few centimeters

00:47:05above paved streets.

00:47:07However, debates persist

00:47:09about the reality of these seismic lights.

00:47:11The Institute of Geological Studies

00:47:13of the United States is cautious

00:47:15because we do not know

00:47:17if these individual testimonies

00:47:19around the time and place

00:47:21of an earthquake

00:47:23really referred to the phenomenon in question.

00:47:25During a study,

00:47:27scientists hypothesized

00:47:29that these lights

00:47:31were released by specific types of rocks

00:47:33during a seismic activity,

00:47:35as if a battery was activated

00:47:37in the earth's crust.

00:47:39Some rocks, such as basalt and gabbro,

00:47:41have tiny crystalline defects.

00:47:43They could potentially release

00:47:45these electric charges.

00:47:47Researchers have estimated that the conditions

00:47:49necessary for the appearance of such lights

00:47:51were only found in less than 0.5%

00:47:53of earthquakes in the world.

00:47:55This could explain their rarity.

00:47:57They also noted that the lights

00:47:59began to appear more often before

00:48:01or during earthquakes than after.

00:48:03A previous study suggested

00:48:05that tectonic pressure

00:48:07could cause a piezoelectric effect,

00:48:09where rocks containing quartz

00:48:11generate powerful electric fields

00:48:13when they are compressed.

00:48:15However, the study of seismic lights

00:48:17remains difficult because they are unpredictable

00:48:19and short-lived.

00:48:23It is time to talk about these mysterious halos

00:48:25that suddenly appear around the moon

00:48:27and the sun.

00:48:29You are walking with a friend

00:48:31and suddenly you see it.

00:48:33It is a warning from Mother Nature.

00:48:35A snowstorm or rain is coming.

00:48:37These halos are formed when billions

00:48:39of tiny ice crystals in the clouds

00:48:41refract the light of the sun.

00:48:43Resist the temptation to admire

00:48:45this prodigy with the naked eye.

00:48:47It can damage your eyes.

00:48:49Take sunglasses and observe it

00:48:51for about forty minutes at most.

00:48:53Nature sends us

00:48:55many early warnings.

00:48:57If the sea mysteriously withdraws,

00:48:59revealing corals and fish,

00:49:01a tsunami could be approaching.

00:49:03Also pay attention to the current

00:49:05of tornadoes on the beach.

00:49:07And sharks could venture further

00:49:09than usual if a storm escapes.

00:49:11You feel your hair stand up

00:49:13and your jewels vibrate.

00:49:15It is lightning that could fall nearby.

00:49:17Quickly seek shelter.

00:49:19Avalanches, green storms and lakes

00:49:21near volcanoes all present potential dangers.

00:49:23The cross-sea is just as dangerous.

00:49:25And practicing speleology

00:49:27during a full moon could cost you your life.

00:49:29If the ocean turns red,

00:49:31avoid swimming there.

00:49:33There could be toxic algae in the water.

00:49:35Animals also detect disasters.

00:49:37If they behave strangely,

00:49:39be careful.

00:49:43A fascinating bluish glow

00:49:45appears around the Matsu Islands

00:49:47during summer nights.

00:49:49It is caused by tiny luminous creatures,

00:49:51known as sea turtles.

00:49:53Tourists love to observe this spectacle.

00:49:55But there is a drawback.

00:49:57It is toxic and increases in size every year,

00:49:59as revealed by a study.

00:50:01Despite its enchanting appearance,

00:50:03the phenomenon is harmful.

00:50:05A team of oceanographers

00:50:07used satellite data

00:50:09to track its progress over 19 years.

00:50:11After analyzing nearly a thousand images,

00:50:13they concluded that it extended

00:50:15to deeper waters.

00:50:17Unfortunately, this expansion

00:50:19has affected sea turtles

00:50:21and even human health.

00:50:23Although dinoflagellates are not harmful,

00:50:25their toxic algae-composed diet

00:50:27releases toxic chemical compounds in the water.

00:50:29This process also exhausts oxygen,

00:50:31endangering marine fauna.

00:50:33The main cause is uncertain.

00:50:35But pollution from agriculture

00:50:37practiced along the Yangtze River

00:50:39seems to play a crucial role.

00:50:41Agricultural rustle

00:50:43introduces nutrients

00:50:45that feed this flora.

00:50:47As a result of the Three Gorges Dam,

00:50:49the size of the phenomenon decreased

00:50:51when the flow of the river decreased.

00:50:53Then, after the completion of the dam

00:50:55and the return of a powerful current,

00:50:57it became more beautiful.

00:50:59Researchers predict that

00:51:01these blue tears will continue to extend,

00:51:03posing a constant threat to marine life

00:51:05and producing more and more luminous waters.

00:51:09A catabatic wind occurs

00:51:11when cold and dense air

00:51:13descends along a mountain slope

00:51:15These winds can be powerful,

00:51:17sometimes reaching the speed of a hurricane.

00:51:19But this is rare.

00:51:21Unlike other descending winds,

00:51:23catabatic winds such as the Adriatic storm

00:51:25or the Santa Ana wind in California

00:51:27come from air that cools

00:51:29in high reliefs like

00:51:31plateaus or mountains.

00:51:33As the air descends,

00:51:35it warms up and its temperature

00:51:37depends on its source region.

00:51:39In Antarctica, catabatic winds

00:51:41play a crucial role in the formation

00:51:43of wind turbines,

00:51:45and in this region,

00:51:47as well as in Greenland,

00:51:49they can be particularly intense

00:51:51and reach the strength of a hurricane.

00:51:53They contribute to unique phenomena

00:51:55such as the dry valleys of McMurdo

00:51:57in Antarctica and are associated

00:51:59with the feared Willy Woes

00:52:01sweeping the archipelago of

00:52:03the Land of Fire and Alaska.

00:52:05The fire of Saint Helm is a natural phenomenon

00:52:07that deserves to be mentioned.

00:52:09It occurs during storms

00:52:11and volcanic eruptions

00:52:13when a powerful electric field

00:52:15reigns over the area.

00:52:17It produces a purple or bluish glow

00:52:19around the masts of ships,

00:52:21aircraft stops or pointed objects.

00:52:23This glow is caused by ionized air molecules

00:52:25and is the most visible

00:52:27in low-light conditions.

00:52:29It is a form of plasma

00:52:31that manifests when the electric field

00:52:33around an object causes the ionization

00:52:35of air molecules.

00:52:37This can occur during storms

00:52:39or when there is a tension

00:52:41between clouds and the ground.

00:52:43Glowing objects facilitate the appearance

00:52:45of the fire of Saint Helm

00:52:47because the electric field

00:52:49is more concentrated.

00:52:51The colors you see,

00:52:53whether blue or purple,

00:52:55come from the fluorescence

00:52:57of nitrogen and oxygen

00:52:59in the Earth's atmosphere.

00:53:01It is similar to the way

00:53:03our neon lamps work

00:53:05but with different gases.

00:53:08The engineers make the wings

00:53:10of the aircraft smooth

00:53:12to allow the air to circulate

00:53:14easily around their surface

00:53:16and reduce resistance during flight.

00:53:18So why did they add

00:53:20these convex yellow hooks?

00:53:22They obviously harm aerodynamics.

00:53:24Of course, but they are also

00:53:26necessary for your safety.

00:53:28Imagine an airplane

00:53:30making an emergency landing

00:53:32in the middle of the sea.

00:53:34Everything goes well,

00:53:36but the passengers have to

00:53:38walk on the wings

00:53:40to get off.

00:53:42They leave the plane

00:53:44by the emergency exits

00:53:46above the wings.

00:53:48Before the door opens,

00:53:50the evacuation slide

00:53:52inflates.

00:53:54The passengers have to

00:53:56walk on the wing

00:53:58and get off on the slide,

00:54:00but the surface of the wing

00:54:02is slippery because of the water.

00:54:04During the evacuation,

00:54:06people can hang onto

00:54:08this rope to avoid falling.

00:54:10With a rope,

00:54:12you can also attach

00:54:14the rescue ropes to the wing

00:54:16so that the currents

00:54:18don't take them away from the plane.

00:54:20The plane can float

00:54:22for 10 to 60 minutes

00:54:24depending on the model,

00:54:26the weather conditions

00:54:28and the pilot's skills.

00:54:30The main exit and the emergency exit

00:54:32During an evacuation,

00:54:34people can panic and accidentally

00:54:36push the air hostesses.

00:54:38To avoid a fall,

00:54:40they cling to their wrists.

00:54:42The seat belt in an airplane

00:54:44has a slightly different function

00:54:46than that of your car.

00:54:48The seat belt protects you

00:54:50from a horizontal shock.

00:54:52When a plane goes through turbulence,

00:54:54it is shaken from top to bottom.

00:54:56Your seat belt prevents you

00:54:58from hitting the ceiling with your head.

00:55:00If a person behaves badly

00:55:02and disturbs the flight,

00:55:04the flight attendants

00:55:06have the right to attach it to their seat.

00:55:08To do this, they use police buttons

00:55:10or plastic clips.

00:55:12This is the maximum that can be done

00:55:14during the flight.

00:55:16Then they report the person

00:55:18to the airport and the police

00:55:20after landing.

00:55:22In case of emergency,

00:55:24oxygen masks fall automatically.

00:55:26They have an additional function

00:55:28Air pressure can change

00:55:30because of turbulence.

00:55:32So, among other things,

00:55:34masks help passengers to stay calm.

00:55:36Your seat is your best ally.

00:55:38The life jacket

00:55:40will prevent you from drowning.

00:55:42In addition, the surface of the seat

00:55:44is made of waterproof material.

00:55:46If water enters the cabin,

00:55:48the seat will prevent you from freezing

00:55:50since it will not be wet.

00:55:52It is also waterproof.

00:55:54The cover can prevent the fire

00:55:56from spreading.

00:55:58Of course, you will probably never

00:56:00use this function,

00:56:02but it is always good to feel safe,

00:56:04isn't it?

00:56:06You can use the tablet in front of you

00:56:08to make a footrest.

00:56:10You just have to attach a belt,

00:56:12a cover or a towel around the table

00:56:14and hang your feet there.

00:56:16You may have noticed black triangles

00:56:18on the wall above the seats.

00:56:20For you, as a passenger,

00:56:22they can indicate the seats

00:56:24where you can take the most beautiful flight photos.

00:56:26But the triangles were not created

00:56:28for your camera.

00:56:30The crew members monitor the aircraft

00:56:32by the windows located under the panels.

00:56:34Let's imagine that the wings are freezing,

00:56:36that the engine is on fire

00:56:38or that the pilot receives a signal

00:56:40about any problem.

00:56:42In this case, the crew quickly heads

00:56:44towards the triangles and evaluates the situation.

00:56:46And you, you are there,

00:56:48sitting under the triangle,

00:56:50looking at the wing and thinking

00:56:52how to attach it to the lower part of the aircraft.

00:56:54They could have installed them above the windows

00:56:56or in the middle.

00:56:58In fact, some aircraft have them in the middle

00:57:00or even higher.

00:57:02And each location makes sense.

00:57:04The engine and the turbines are under the wings.

00:57:06It is much easier to repair them

00:57:08since they are close to the ground.

00:57:10And in case of emergency landing,

00:57:12the wings serve as lifeboats.

00:57:14They help to keep the aircraft on the water.

00:57:16The empty fuel tanks under the wing

00:57:18can also help the aircraft

00:57:20to stay on the surface.

00:57:22But this position also presents some risks.

00:57:24Debris from the runway

00:57:26can get into the turbines.

00:57:28Fortunately, this is unlikely to happen

00:57:30since the runways are carefully cleaned.

00:57:32The aircraft with the wings in the middle

00:57:34have the least resistance to the air.

00:57:36The fighter aircraft

00:57:38and the supersonic aircraft

00:57:40are designed in this way.

00:57:42The big cargo aircraft have their wings

00:57:44at the top of the wing.

00:57:46Thanks to this, the aircraft is closer to the ground

00:57:48and it is easier to load the cargo.

00:57:50In addition, it is safer to land

00:57:52on unprepared runways

00:57:54with high wings

00:57:56because debris will not get into the turbines.

00:57:58The aerodynamics of these aircraft

00:58:00work better thanks to such wings.

00:58:02They have less resistance to the air

00:58:04and deliver goods more quickly.

00:58:06The oxygen inside the masks

00:58:08is a combination of chemical products.

00:58:10Transporting oxygen reserves

00:58:12would be too expensive for the airline.

00:58:14It would take up a lot of space

00:58:16and increase the weight

00:58:18which would lead to an additional

00:58:20consumption of fuel.

00:58:22As a result, there is a chemical oxygen generator

00:58:24located in the panel above your head.

00:58:26A small tank

00:58:28contains barium, sodium

00:58:30and potassium compounds

00:58:32which mix and create a hot chemical reaction

00:58:34that releases oxygen

00:58:36and makes it pass through the mask.

00:58:38The small holes in the hulls

00:58:40prevent the glass from breaking.

00:58:42The air pressure inside the aircraft

00:58:44is higher than outside.

00:58:46The difference is so great

00:58:48that the air can simply break the glass.

00:58:50To avoid this,

00:58:52small holes are drilled.

00:58:54The air passes through and reduces the load on the glass.

00:58:56Moreover, the hulls have an oval shape

00:58:58for the same reason.

00:59:00It is the ideal shape for a uniform air distribution.

00:59:02If they were square

00:59:04or triangular,

00:59:06moisture would accumulate in the corners

00:59:08which could also break them.

00:59:10In addition, all the water is dried

00:59:12The hulls are made of triple glazing.

00:59:14The outer glass

00:59:16holds the pressure.

00:59:18The middle one works like a fuse.

00:59:20The third layer protects the second layer

00:59:22of passengers who like to touch it.

00:59:24Technically, the aircraft could fly

00:59:26with only one layer, but it would be dangerous.

00:59:28An additional protection exists for the wheels.

00:59:30They undergo enormous loads

00:59:32during landing.

00:59:34But don't worry, they won't burst.

00:59:36The tires can withstand

00:59:38a pressure 5 to 7 times higher

00:59:40than what they actually endure.

00:59:42You see the toilet panel on the door?

00:59:44There is a secret compartment below.

00:59:46The crew members can unlock

00:59:48the door from the outside.

00:59:50So don't expect total privacy.

00:59:52Of course, it is forbidden

00:59:54for other passengers to do it.

00:59:56But the cabin crew can open it

00:59:58in case of emergency.

01:00:00When the on-board agents pass through the cabin during the flight,

01:00:02they always touch the upper compartments

01:00:04above the seats.

01:00:06They don't check if they are well closed.

01:00:08Along the compartments,

01:00:10there are handles in the shape of a lace.

01:00:12The air hostesses hang on to it

01:00:14so as not to fall.

01:00:16It is quite practical, especially for those

01:00:18who don't like to touch the passengers' seats

01:00:20while going to the toilet.

01:00:22There is an important reason

01:00:24why the turbines are located under the wings.

01:00:26Previously, they were placed at the level

01:00:28of the tail of the aircraft

01:00:30to improve the aerodynamics of the flight.

01:00:32If one of the engines stopped working,

01:00:34the cabin wouldn't shake so much.

01:00:36In addition, the wings were thinner

01:00:38thanks to the turbines located

01:00:40at the level of the tail,

01:00:42which was also better for aerodynamics.

01:00:44But it turned out that such a location

01:00:46led to additional costs.

01:00:48The engine in the tail was not very practical

01:00:50to maintain.

01:00:52It was high, so it took

01:00:54special equipment and more time

01:00:56to maintain it.

01:00:58And of course, it affected the price of the ticket.

01:01:00So we started to install the turbines

01:01:02under the wings to save money

01:01:04and time.

01:01:06Have you ever noticed a flashing light

01:01:08in the cabin before take-off?

01:01:10It happens when the pilot disconnects

01:01:12the aircraft from the airport's electrical network

01:01:14and switches to the onboard network.

01:01:16This rapid transition can cause flashings.

01:01:22Is the sky like a desert?

01:01:24Can a straight-line aircraft go faster

01:01:26than the speed of sound?

01:01:28Can we repair an aircraft with a piece of adhesive tape?

01:01:30Let's see if your intuitions are good

01:01:32and share your answers in the comments.

01:01:40So here's a first one for you.

01:01:42Straight-line aircraft are more fuel-efficient

01:01:44than your car.

01:01:46True or false?

01:01:48Well, it's true.

01:01:50Commercial flights are more fuel-efficient

01:01:52per person and per kilometer than cars,

01:01:54and for more than a decade.

01:01:56More advanced technologies

01:01:58and a larger number of passengers per aircraft

01:02:00make up almost 74%.

01:02:02As for cars,

01:02:04the decrease was only 57%.

01:02:06OK,

01:02:08what do you think of this?

01:02:10There is no 13 in an aircraft.

01:02:12Now that I think about it,

01:02:14I've never seen a 13A or any letter

01:02:16next to this number on a boarding pass.

01:02:18And you?

01:02:20It's true, but only in part.

01:02:22In countries where the number 13 is considered

01:02:24to be unfortunate, there is no 13.

01:02:26But in other countries,

01:02:28the difference will be different

01:02:30depending on local superstitions.

01:02:32Opening an aircraft door during a flight

01:02:34is a real risk for safety.

01:02:36It sounds pretty scary,

01:02:38but is it true?

01:02:40You can relax, it's just a myth.

01:02:42First of all, the doors are locked,

01:02:44but even if they weren't,

01:02:46no one could open the door of an aircraft during a flight.

01:02:48It's physically impossible.

01:02:50The pressure of the cabin

01:02:52doesn't allow it.

01:02:54When an aircraft is at its cruising altitude,

01:02:56the cabin is pressurized.

01:02:58The difference in pressure

01:03:00between the interior and the exterior

01:03:02is huge.

01:03:04In other words,

01:03:06the pressure inside the cabin

01:03:08pushes the door and prevents its opening.

01:03:10Even better,

01:03:12aircraft doors are so-called

01:03:14plug-type doors,

01:03:16which means that the interior edge

01:03:18is wider than the exterior edge.

01:03:20So it works like the plug

01:03:22of a bathtub,

01:03:24what do you think?

01:03:26If you think it's true,

01:03:28you're absolutely right.

01:03:30The cabin of an aircraft is pressurized,

01:03:32and the humidity is set at 20%.

01:03:34For comparison,

01:03:36in the Sahara desert,

01:03:38the average air humidity is about 25%,

01:03:40and your skin is used to at least 40% humidity.

01:03:42That's why your nose

01:03:44and throat are so dry

01:03:46when you take the plane.

01:03:48Several years ago,

01:03:50someone posted a photo on the Internet

01:03:52of a technician

01:03:54of an airline.

01:03:56He seemed to be repairing

01:03:58a plane with an adhesive tape.

01:04:00So here's the question.

01:04:02Could it be true,

01:04:04or was it just an editing?

01:04:06The answer is not so simple.

01:04:08It was not an ordinary tape.

01:04:10So in part,

01:04:12it's a myth.

01:04:14But it was a kind of adhesive tape

01:04:16known as speed tape.

01:04:18It costs about $700 per roll.

01:04:20It's used for small temporary repairs,

01:04:22waiting to be able to do real repairs.

01:04:24Is it true that pilots

01:04:26avoid the Bermuda Triangle?

01:04:28After all, it has such a bad reputation.

01:04:30Ships and planes

01:04:32seem to disappear in large numbers

01:04:34in this region.

01:04:36It's obviously just a myth.

01:04:38Today, we know that there is no particular

01:04:40danger of flying over the Bermuda Triangle,

01:04:42and planes cross this region

01:04:44every day.

01:04:46Planes generally fly alone.

01:04:48Thanks to automatic piloting systems

01:04:50that do all the work.

01:04:52Myth or truth?

01:04:54What do you think?

01:04:56It's a very widespread myth.

01:04:58Many people think that planes

01:05:00have fully automated mechanisms

01:05:02that allow them to fly alone.

01:05:04And pilots would only be there

01:05:06as reinforcement.

01:05:08But in reality,

01:05:10flying is manual work.

01:05:12It requires constant attention

01:05:14and a competent crew.

01:05:16Is it true?

01:05:18Or is it just a myth?

01:05:20This fact is not a myth.

01:05:22The Concorde

01:05:24could reach a speed of

01:05:262,140 km per hour.

01:05:28It's much faster than the speed of sound,

01:05:30which is about

01:05:321,234 km per hour.

01:05:34It's almost twice as slow

01:05:36as the Concorde.

01:05:38You've probably heard

01:05:40about this terrifying fact.

01:05:42Planes would empty their toilets

01:05:44in mid-flight.

01:05:46But is it true?

01:05:48Fortunately, it's just a myth.

01:05:50There is no ounce of truth in it.

01:05:52Aircraft toilets

01:05:54use a suction system

01:05:56that moves the contents of the toilet

01:05:58to a special reservoir.

01:06:00This is located in the back of the plane.

01:06:02And this reservoir is only emptied

01:06:04after landing.

01:06:06Ah! Here's a tricky question.

01:06:08A plane flying east

01:06:10would reach higher speeds.

01:06:12Does the speed really depend

01:06:14on the direction of the aircraft?

01:06:16And...

01:06:18It's true!

01:06:20This is made possible by high-altitude winds,

01:06:22also known as jet current.

01:06:24They blow at a speed

01:06:26between 241 and 482 km per hour.

01:06:28And since our planet rotates

01:06:30from east to west,

01:06:32planes moving in this direction

01:06:34can use these winds

01:06:36to move faster.

01:06:38Do you think that pilots control

01:06:40the pressure in the cabin

01:06:42to save fuel?

01:06:44It's a myth.

01:06:46If you ask this question to a pilot,

01:06:48he'll tell you it's totally ridiculous.

01:06:50The truth is that the pressure

01:06:52determines the level of oxygen in the cabin.

01:06:54Here's another one.

01:06:56The world's largest air traffic control tower

01:06:58is as high as a skyscraper.

01:07:00Do you think it's true?

01:07:02Or is it still a myth?

01:07:04I know, it's hard to believe,

01:07:06but it's true.

01:07:08To land, a plane needs

01:07:10runway lights and air traffic control beacons.

01:07:12And they are under the responsibility

01:07:14of the control tower.

01:07:16It also manages ground traffic.

01:07:18No wonder

01:07:20such buildings must be very high.

01:07:22Bangkok's new international airport

01:07:24in Thailand

01:07:26has a 132-meter-high tower.

01:07:28Its height is about

01:07:30equal to that of a 40-story building.

01:07:32The construction of this tower

01:07:34cost 18 million euros.

01:07:36I have another difficult question for you.

01:07:38The sensitivity of your taste buds

01:07:40decreases by 30%

01:07:42during a flight.

01:07:44True or false?

01:07:46It's true.

01:07:48The pressure in the cabin

01:07:50associated with the air's dryness

01:07:52thickens your taste buds a bit.

01:07:54But the most curious thing here

01:07:56is that it mostly affects the salty and sweet flavors.

01:07:58If you're served something spicy

01:08:00or bitter,

01:08:02you won't have any problem knowing it.

01:08:04Aircraft manufacturers try to take into account

01:08:06the reduced sensitivity of your taste buds

01:08:08when they prepare airplane meals.

01:08:10They have to modify our good old recipes

01:08:12so that your food tastes better.

01:08:16In case the cabin is depressurized,

01:08:18your oxygen mask is immediately available

01:08:20and you can relax and breathe.

01:08:22You can even use it until the end of the flight.

01:08:24I'd like it to be true, but is it?

01:08:26Unfortunately,

01:08:28it's just a myth.

01:08:30Passengers' oxygen masks usually provide

01:08:32enough oxygen to breathe normally

01:08:34for 10 to 15 minutes.

01:08:36In other words, it's just a temporary solution.

01:08:38But in most cases,

01:08:40this time is enough for the plane to descend

01:08:42to 3,050 meters.

01:08:44And at this altitude,

01:08:46we don't need a mask to breathe.

01:08:48As the planes descend very quickly,

01:08:50additional oxygen is only necessary

01:08:52for a few minutes at most.

01:08:54Besides, oxygen systems

01:08:56are regularly tested during maintenance checks.

01:08:58In addition,

01:09:00passengers' and pilots' oxygen levels

01:09:02do not depend on electricity.

01:09:04Masks use

01:09:06individual oxygen generators.

01:09:08Thus, even if there is an electricity problem on board,

01:09:10the arrival of oxygen will not be cut.

01:09:12Many people say

01:09:14that the plane is the safest means of transport.

01:09:16What do you think?

01:09:18It's a myth.

01:09:20The plane is the second safest means of transport.

01:09:22Studies have shown that the elevator

01:09:24is safer than the plane.

01:09:26Unfortunately, this is not how you can go to the Bahamas.

01:09:28Ok,

01:09:30this last question was a joke.

01:09:32Statistically, the plane is indeed

01:09:34the safest way to travel.

01:09:36So, how many good answers do you have?

01:09:38Tell me in the comments below.

01:09:40I did 8. Not great.

01:09:58I did 8. Not great.

01:10:00I did 8. Not great.

01:10:02I did 8. Not great.

01:10:04I did 8. Not great.

01:10:06I did 8. Not great.

01:10:08I did 8. Not great.

01:10:10I did 8. Not great.

01:10:12I did 8. Not great.

01:10:14I did 8. Not great.

01:10:16I did 8. Not great.

01:10:18I did 8. Not great.

01:10:20I did 8. Not great.

01:10:22I did 8. Not great.

01:10:24I did 8. Not great.

01:10:26More precisely,

01:10:28when their seeds are ripe.

01:10:30Ripe seeds have developed special coatings

01:10:32that protect them when they

01:10:34pass through the digestive system of animals.

01:10:36Why is our skin

01:10:38tingling

01:10:40after spending time in the water?

01:10:42After 5 to 10 minutes in the bathtub,

01:10:44you will notice that small ripples

01:10:46form on your feet and hands.

01:10:48Scientists suppose that this

01:10:50could be the way our body

01:10:52obtains better adhesion

01:10:54when immersed in a slippery environment.

01:10:56Our wrinkled fingers improve

01:10:58our grip on submerged or wet objects.

01:11:00In addition, they channel water

01:11:02in a similar way to the tires

01:11:04for rain on car tires.

01:11:06When you eat something

01:11:08very acidic, you don't feel it

01:11:10only on your tongue.

01:11:12Sometimes your whole face seems to contract

01:11:14so that everyone around can see

01:11:16that you are having a bad time.

01:11:18The bitter taste that causes this reaction

01:11:20is the result of the hydrogen ions

01:11:22that acids release when they mix

01:11:24with saliva.

01:11:26When your mouth detects this sign of an acid,

01:11:28it sends you a message in a spectacular way

01:11:30so that you can't ignore it.

01:11:32It is an evolutionary response

01:11:34that made sense in ancient times

01:11:36because many plants that our ancestors

01:11:38found in nature and then wanted to

01:11:40consume were toxic,

01:11:42especially plants with an acid taste.

01:11:44So even today, your gustatory receptors

01:11:46put you on alert and your face

01:11:48twists uncontrollably

01:11:50when you taste something like this.

01:11:52A lighter color on an airplane

01:11:54is actually heavier

01:11:56than a darker paint.

01:11:58White requires a solid content

01:12:00higher than black to obtain

01:12:02the necessary saturation.

01:12:04However, the higher the solid content is,

01:12:06the heavier the paint will be.

01:12:08This is why white paint is one of the heaviest.

01:12:10But white planes

01:12:12are more effective than black ones,

01:12:14although it also depends on how

01:12:16we define effective.

01:12:18White paint reflects more

01:12:20sunlight than black paint.

01:12:22Different colors absorb

01:12:24different wavelengths of light

01:12:26and white objects heat up

01:12:28more slowly than darker objects.

01:12:30This means that the plane

01:12:32doesn't overheat.

01:12:34If your hot tea tastes weird

01:12:36when you drink it in a plastic cup,

01:12:38don't worry, it's normal.

01:12:40You might think that tea

01:12:42dissolves a part of the plastic,

01:12:44but that's probably not the case.

01:12:46It's just the result of your taste buds.

01:12:48All your senses contribute.

01:12:50That's why strawberry mousse

01:12:52tastes sweeter on a white plate

01:12:54than on a black plate.

01:12:56And that's why you think

01:12:58that crisps are crunchier

01:13:00when you hear those high-frequency sounds

01:13:02while eating them.

01:13:04Likewise, hot chocolate tastes better

01:13:06when you drink it in an orange cup.

01:13:08We are conditioned to drink hot tea

01:13:10in ceramic cups.

01:13:12That's why seeing it in a plastic cup

01:13:14makes us unconsciously expect

01:13:16hot tea from a distributor that doesn't taste good.

01:13:18Pink flames

01:13:20often stay on one leg

01:13:22and a theory states that

01:13:24it helps them keep their body heat.

01:13:26One proof is that

01:13:28they often raise their leg in water

01:13:30than on land.

01:13:32Others think that's how they save energy

01:13:34and not heat.

01:13:36These birds are definitely more stable

01:13:38on one leg when it comes to

01:13:40standing for long periods.

01:13:42That's because they can lock the tendons

01:13:44and ligaments of their legs in a stable position.

01:13:46That means their muscles

01:13:48don't have to work hard

01:13:50to stay in the same place.

01:13:52And that gives them an inimitable look.

01:13:54Why do repetitive sounds

01:13:56annoy us so much?

01:13:58It's simple.

01:14:00They constantly attract our attention

01:14:02and prevent us from focusing on something else.

01:14:04We quickly stop reacting to repetitive sounds

01:14:06like the ticking of a clock.

01:14:08But some are simply

01:14:10too annoying, like a dripping tap.

01:14:12The reason why it bothers us so much

01:14:14is the lack of control.

01:14:16If you know you can stop the sound

01:14:18when you want to, you won't find it

01:14:20as painful.

01:14:22Why do all the planets

01:14:24make circles around the sun in the same direction?

01:14:26It would be great to go back

01:14:284.6 billion years.

01:14:30You could see that space was not empty

01:14:32at the time, even if our solar system

01:14:34was not yet formed.

01:14:36There was a cloud of dust and gas

01:14:38in the place where our sun

01:14:40and the planets are today.

01:14:42This cloud was like a solar nebula

01:14:44and it shaped our solar system.

01:14:46In a simplified way,

01:14:48a nebula is a huge cloud of gas

01:14:50and dust that occupies the space

01:14:52between the stars and helps to form

01:14:54new ones, as well as the planets

01:14:56that gravitate around them.

01:14:58When this nebula collapsed,

01:15:00its center became our sun,

01:15:02while the rest of the matter gathered

01:15:04and created the planets we know today

01:15:06as well as their moons

01:15:08and the rest of the rocky bodies,

01:15:10like asteroids.

01:15:12The matter was spinning fast

01:15:14and the process looked a bit like

01:15:16pizza dough flattening

01:15:18into a increasingly large disk.

01:15:20As the cloud was moving in a certain direction

01:15:22at the beginning, all the planets

01:15:24also kept the same orbital plane.

01:15:26Something massive would have to happen

01:15:28to modify the orbit of a planet

01:15:30and force it to spin around the sun

01:15:32in the opposite direction.

01:15:34Why do some people have such a beautiful voice

01:15:36when they sing?

01:15:38Three elements affect the general range

01:15:40of sounds that come out of your mouth.

01:15:42The strength of your diaphragm,

01:15:44the size of your vocal folds

01:15:46and the shape of the chambers of your sinuses.

01:15:48But making the sound beautiful

01:15:50is largely a matter of practice.

01:15:52At a basic level, you hear a note

01:15:54and you reproduce it with your voice.

01:15:56But the real difference between being

01:15:58simply able to sing a note

01:16:00and having a beautiful voice

01:16:02is the muscular reactions

01:16:04that are mostly unconscious.

01:16:06They adjust your muscular mechanism

01:16:08where you produce your voice

01:16:10according to the emotions you feel while singing.

01:16:12As with other musical instruments,

01:16:14a greater finger amplitude

01:16:16can help you play the piano.

01:16:18But the rest consists of learning

01:16:20these subtle things like the pressure on the keys

01:16:22and the rhythm.

01:16:24Why do dogs hear sounds

01:16:26that are higher than us?

01:16:28Humans hear frequencies up to about 20 kHz

01:16:30and birds hear frequencies

01:16:32up to 45 kHz.

01:16:34Almost all mammals

01:16:36can hear frequencies

01:16:38higher than other vertebrates.

01:16:40Birds hear frequencies

01:16:42up to 12 kHz

01:16:44and reptiles, amphibians

01:16:46and fish hear frequencies

01:16:48up to 5 kHz.

01:16:50Mammals do not need to hear

01:16:52high frequencies to communicate with each other,

01:16:54but to be able to locate

01:16:56the origin of a certain sound.

01:16:58Our brain compares the frequency range

01:17:00of a sound when it reaches each ear.

01:17:02The head goes from the shadow to an ear

01:17:04so that some of the frequencies

01:17:06are absorbed.

01:17:08And our brain absorbs more high frequencies

01:17:10than low frequencies.

01:17:12And the smaller the head,

01:17:14the less it has an effect on low-frequency sounds.

01:17:16This is why the animal must be able

01:17:18to hear high frequencies

01:17:20to hear a wider range of sounds.

01:17:22A mouse must hear up to 90 kHz

01:17:24and an elephant can hear up to 10 kHz.

01:17:26Dogs have a head

01:17:28smaller than ours,

01:17:30so they are in the intermediate category.

01:17:32Why are oceans salty?

01:17:34Chemically speaking,

01:17:36salt is sodium chloride

01:17:38and the salt of the ocean

01:17:40is not only composed of these two elements

01:17:42but also of many other ions

01:17:44such as calcium and magnesium.

01:17:46Most of them start

01:17:48like rocks on the ground.

01:17:50Some factors, such as wind and rain,

01:17:52erode these rocks,

01:17:54and salt gradually wears them away.

01:17:56So we can say that most of the salt

01:17:58in the ocean comes from rocks.

01:18:00The minerals in these rocks

01:18:02are washed away in streams and rivers

01:18:04which transport salt into the ocean.

01:18:06About 85% of the ions in the ocean

01:18:08are sodium and chloride,

01:18:10while magnesium and sulfate

01:18:12account for about 10%.

01:18:14And a part of the salt

01:18:16that is found in the ocean

01:18:18does not remain there.

01:18:20Animals consume a large part of it.

01:18:22Thanks to a regular supply of water

01:18:24from the surface,

01:18:26the levels of salinity are almost constant.

01:18:28The ocean also draws its salt

01:18:30from another source,

01:18:32the hydrothermal fluids.

01:18:34The magma from the depths

01:18:36of the earth's crust

01:18:38heats the depths' events.

01:18:40When they are hot enough,

01:18:42they cause chemical reactions

01:18:44between the sea water

01:18:46and all the minerals in the rocks

01:18:48around the events.

01:18:50This is the place

01:18:52where you find yourself in the world.

01:18:54The most famous survival rule

01:18:56concerning a face-to-face

01:18:58with a bear is to stay still

01:19:00and pretend to be dead.

01:19:02But this rule will not work

01:19:04with all bears,

01:19:06only with grizzlies and brown bears.

01:19:08If you are in North America,

01:19:10you will find them in Alaska,

01:19:12in the state of Washington,

01:19:14Montana, Idaho and Wyoming.

01:19:16Black bears,

01:19:18in California,

01:19:20can be found in

01:19:2240 states of America,

01:19:24a large part of Canada

01:19:26and even some regions

01:19:28of northern Mexico.

01:19:30So, if you go to Yellowstone,

01:19:32you could come across

01:19:34a black bear or a grizzly.

01:19:36But if you are in California,

01:19:38the bear you will come across

01:19:40by accident will most likely

01:19:42be a black bear.

01:19:44And no,

01:19:46it will not be a grizzly.

01:19:48It's complicated, isn't it?

01:19:50If you notice a bump on the shoulders

01:19:52of your impromptu guest,

01:19:54it's a grizzly.

01:19:56Black bears don't have it.

01:19:58A grizzly will also have a more

01:20:00deep face, round ears

01:20:02and long, light-colored claws.

01:20:04The black bear has a straight muzzle,

01:20:06similar to that of a dog,

01:20:08pointed ears and darker claws.

01:20:10There will be an interlude on this

01:20:12a little later.

01:20:14So, if you are sure

01:20:16it's a grizzly or a brown bear,

01:20:18lie down,

01:20:20take a fetal position,

01:20:22bring your knees

01:20:24against your chest

01:20:26and cover your head

01:20:28to show the bear

01:20:30that you are not a threat.

01:20:32These big bears mainly attack

01:20:34when they feel threatened.

01:20:36But you will never be able

01:20:38to outrun them in a race,

01:20:40so don't even try.

01:20:42In 99% of cases,

01:20:44the bear will pass its way.

01:20:46Wait 2 to 3 minutes

01:20:48until you can no longer hear it

01:20:50nearby.

01:20:52It could stay in the parishes

01:20:54to make sure you are not

01:20:56picked up and,

01:20:58if necessary,

01:21:00go on the attack.

01:21:02If you are ready for such an emergency

01:21:04and you have an anti-bear spray

01:21:06on you,

01:21:08remove the safety clip

01:21:10and simply adopt a fetal position.

01:21:12When the bear is retreating,

01:21:14run in the opposite direction

01:21:16to the predator.

01:21:18You got it.

01:21:20If you are dealing with

01:21:22a black bear,

01:21:24it will not stop when it sees you

01:21:26crouching on the ground.

01:21:28And if you don't have anti-bear spray on you

01:21:30and it seems clearly interested,

01:21:32show it who is the boss.

01:21:34Throw stones or your stuff at it

01:21:36and shout loudly, applaud,

01:21:38make yourself look bigger

01:21:40by raising your arms high

01:21:42and shaking your jacket,

01:21:44climb on a rock or a stem.

01:21:46Do everything you can to scare it.

01:21:48Black bears look a lot like

01:21:50these little thugs at school

01:21:52who want your treat.

01:21:54They will often give up if they see

01:21:56that you can defend yourself.

01:21:58If the bear approaches you dangerously,

01:22:00hit it in the nose or eyes

01:22:02and try to confuse it or stun it

01:22:04to make this unwanted hiking companion

01:22:06and just sit away and watch you.

01:22:08Try to move away very slowly.

01:22:10Move laterally with a slight angle

01:22:12so as not to stumble

01:22:14by retreating far from the danger.

01:22:16In this way, the bear will not think

01:22:18that you are trying to escape

01:22:20and will not be incited to chase you.

01:22:22Speak calmly out loud

01:22:24to show it that you are a human.

01:22:26Singing can also help.

01:22:28Who knows, maybe it will also know the melody.

01:22:30Avoid direct visual contact with the animal

01:22:32and never stand between

01:22:34a bear and its mother.

01:22:36Do not panic if the bear stands on its hind legs.

01:22:38This is not an aggressive demonstration.

01:22:40If you ever plan to visit

01:22:42a region populated by polar bears,

01:22:44do not go there without means of dissuasion.

01:22:46Like a tank, for example.

01:22:48Bad polar bears, in good health,

01:22:50weigh half a ton,

01:22:52are 2 meters tall on their hind legs

01:22:54and can hunt their prey

01:22:56up to 40 km per hour.

01:22:58A group of 3 or more people

01:23:00can be enough to intimidate any bear.

01:23:02So, do not go out alone.

01:23:04Walk with other people

01:23:06and speak loudly during your hike

01:23:08to indicate that you are a group of humans.

01:23:10Do not forget that all polar bears

01:23:12are not eager predators

01:23:14to make you their breakfast.

01:23:16Some of them simply vacate their occupations.

01:23:18If you see one with his head down,

01:23:20sneaking,

01:23:22without trying to go elsewhere

01:23:24but clearly focusing on you,

01:23:26this is where you should worry.

01:23:28Move away slowly from the bear,

01:23:30and use your means of dissuasion

01:23:32only if the bear comes close to you.

01:23:36Some claim that ammonia

01:23:38is an excellent repulsive for bears.

01:23:40They really do not like its smell,

01:23:42so if you soak a few wipes

01:23:44and throw them in the garbage,

01:23:46they should not be interested

01:23:48in your trash.

01:23:50And if you meet a bear in nature

01:23:52and it does not seem to be so interested in you,

01:23:54ammonia could help you repel it.

01:23:56However, ammonia can also

01:23:58damage its nasal voices,

01:24:00depriving the animal of its odor,

01:24:02which means it will no longer be able

01:24:04to find its food.

01:24:06This could also annoy a bear

01:24:08who did not plan to attack you

01:24:10and push it to do so.

01:24:12Everything that has an interesting smell

01:24:14for bears, starting with your food

01:24:16and your garbage,

01:24:18will attract their attention

01:24:20and push them to come inspect your tent.

01:24:22So cook far from the camp

01:24:24and do not spread garbage.

01:24:26The use of anti-bear sprays

01:24:28could be counterproductive.

01:24:30The peppered products they contain

01:24:32may remind them of the smell of food

01:24:34and could be a way to attract bears.

01:24:38If you notice a bear standing

01:24:40on the side of the road,

01:24:42resist the urge to stop

01:24:44to take pictures.

01:24:46Stay at least 100 meters away

01:24:48and park in a safe place.

01:24:50Bears on the side of the road

01:24:52quickly get used to humans

01:24:54and are more likely to approach

01:24:56campsites and picnic areas

01:24:58in search of human food.

01:25:00People who live in the mountains

01:25:02or close to nature

01:25:04are used to the visit of bears

01:25:06and generally do not fear them.

01:25:08Douglas Harder has thus noticed

01:25:10a black bear mother and her two children

01:25:12emptying the bird feeder on his terrace.

01:25:14He also happened to go home

01:25:16after a while

01:25:18to see that a bear had entered

01:25:20his kitchen through a partially open sliding door.

01:25:22The intruder had scratched a wall

01:25:24and chipped some treats

01:25:26before fleeing.

01:25:28Harder had just finished cleaning

01:25:30after the bear when a bear

01:25:32pushed his head through his cat litter.

01:25:34These photos went viral online.

01:25:38Kristen Jones, on the other hand,

01:25:40was visiting her parents in North Carolina

01:25:42and had decided to do yoga

01:25:44on the bank of a lake nearby.

01:25:46She was wearing headphones

01:25:48and did not hear the bear

01:25:50suddenly she felt someone sniffing

01:25:52and licking her neck.

01:25:54She thought it was her neighbor's dog

01:25:56and extended her arm to caress him

01:25:58which scared the animal.

01:26:00Kristen managed to take

01:26:02some pictures of the bear

01:26:04fleeing, although no one

01:26:06believed the story of this licker.

01:26:08She remembers this moment

01:26:10as the scariest in her life

01:26:12and hopes it will never happen again.

01:26:14As for the bear, he was very likely

01:26:16in the parishes in search of food,

01:26:18in trash cans and on people's terraces.

01:26:22Scientists who observe polar bears

01:26:24note how incredibly intelligent

01:26:26these animals are.

01:26:28The members of Polar Bears International

01:26:30took hundreds of pictures

01:26:32to study these animals closely.

01:26:34Before using a special cage,

01:26:36they took their pictures

01:26:38using a device fixed to the end

01:26:40of a long pole which was lowered

01:26:42to a certain height.

01:26:44One day, the flash of the camera

01:26:46flashed right in front of a bear's face.

01:26:48Movies, TV shows

01:26:50and documentaries show us two kinds

01:26:52of situations. You board a cruise ship

01:26:54and you go on a trip.

01:26:56During a storm, the ship sinks.

01:26:58The good news is that you survive.

01:27:00The bad news is that you are

01:27:02in the middle of the sea.

01:27:04In the second situation, you are in a plane.

01:27:06There is a problem. The engines catch fire

01:27:08and the plane crashes into the ocean.

01:27:10The waves surround you and you don't know

01:27:12what to do. In both cases,

01:27:14there is a great chance that you will be saved.

01:27:16Flight controllers usually know

01:27:18very quickly when a plane crashes.

01:27:20And it's the same with big ships.

01:27:22Modern navigation

01:27:24and communication methods help

01:27:26the rescuers to find you quickly,

01:27:28especially if several people are in trouble.

01:27:30But let's imagine

01:27:32a much more terrifying situation.

01:27:34You are in a seaside resort and you tell

01:27:36your friends that you want to eat something.

01:27:38You go to the beach, you buy food

01:27:40and you decide to have lunch at sea.

01:27:42You loosen a catamaran

01:27:44or a small boat, you move away from the shore

01:27:46and you fall asleep.

01:27:48The intense heat wakes you up.

01:27:50You are in the middle of the ocean.

01:27:52You don't know where the shore is

01:27:54or how long you've been there.

01:27:56Fortunately, you have your phone.

01:27:58But the bad news is that it no longer has a battery.

01:28:00At this stage, you can start

01:28:02to worry. But even if it's a cliché,

01:28:04above all, don't panic.

01:28:06The waters around you can make you nervous.

01:28:08To have the impression of being

01:28:10a tiny thing in a huge sea

01:28:12can cause a feeling of terror.

01:28:14But you have to understand that panicking

01:28:16will only make things worse.

01:28:18You have to keep your cool and think.

01:28:20First of all, your situation is

01:28:22advantageous because you have a boat.

01:28:24Some people end up stuck

01:28:26at sea without anything.

01:28:28Your chances of surviving are not so bad.

01:28:30By the way, if you are in the water without a boat

01:28:32but you have pants,

01:28:34you can easily make a life jacket.

01:28:36Just tie the two legs

01:28:38of the pants.

01:28:40Then shake the water with your hand to create bubbles

01:28:42and make it penetrate

01:28:44the pants.

01:28:46After that, grab its upper part to prevent the air

01:28:48from escaping and place it around your neck.

01:28:50Here you have a life jacket.

01:28:52But let's go back to your boat stuck at sea.

01:28:54You don't have pants,

01:28:56just a short and a t-shirt.

01:28:58You have a piece of burrito

01:29:00and a little water in a bottle.

01:29:02Above all, don't drink it all at once.

01:29:04Try to make it last as long as possible.

01:29:06Also know that

01:29:08you must not drink seawater.

01:29:10The salt it contains will make you even more thirsty

01:29:12and your body will be in danger.

01:29:14You must collect fresh water when it rains.

01:29:16Keep your bottle open

01:29:18and let the rain wet your clothes.

01:29:20The important thing is that if you swam

01:29:22in the sea in these clothes,

01:29:24they will be covered with a thin layer of salt.

01:29:26So, first,

01:29:28let the rainwater soak your t-shirt

01:29:30then strain it to remove all the salt.

01:29:32After that,

01:29:34you can use your clothes

01:29:36to collect drinking water.

01:29:38You now have a whole bottle of fresh water.

01:29:40Take a few sips several times a day

01:29:42and you will have enough for a week.

01:29:44Now you have to catch some fish.

01:29:46The good news is that

01:29:48the marine creatures have approached you.

01:29:50The boat attracts their attention.

01:29:52They come to you out of curiosity

01:29:54or to use your boat as a shelter.

01:29:56You just have to catch your lunch.

01:29:58If you wear shoes,

01:30:00use your laces or tear a piece of fabric

01:30:02to make a small rope.

01:30:04Tie a piece of your burrito

01:30:06or any other object to the end of the rope

01:30:08and start fishing.

01:30:10Now you have food and water

01:30:12and nothing to fear,

01:30:14except for sharks.

01:30:16The colors live

01:30:18or a drop of blood can attract them.

01:30:20You can scare them by screaming

01:30:22and beating the water with your hands

01:30:24making noise.

01:30:26They will think they have come

01:30:28to a very dangerous beast,

01:30:30but it is rather something

01:30:32that we see in the movies.

01:30:34But if you have to do something,

01:30:36it is better to give them a blow on the nose

01:30:38than to panic in the water.

01:30:40So you have fish, water

01:30:42and a little authority.

01:30:44Life is beautiful,

01:30:46but you are missing something.

01:30:48Ah yes, you have to join

01:30:50the mainland to survive.

01:30:52You can attract the attention

01:30:54of a plane or a passing ship.

01:30:56Don't worry if you don't have

01:30:58a gadget to reflect the light of the sun

01:31:00and use this beam as a signal.

01:31:02There is a good chance that people

01:31:04on a ship or even pilots

01:31:06in a plane see it.

01:31:08Keep your phone ready

01:31:10so as not to miss an opportunity.

01:31:12In fact, many boats are equipped

01:31:14with lighting rockets and life jackets

01:31:16equipped with reflectors.

01:31:18Use them at night

01:31:20and people will see you from afar.

01:31:22Alas, your tourist boat does not have one.

01:31:24Your phone is therefore your only way

01:31:26if you don't see anyone who could save you.

01:31:28If you don't see the coast,

01:31:30look at the water.

01:31:32The closer you are to the shore,

01:31:34the clearer it will be,

01:31:36so if you can distinguish a less dark shade,

01:31:38you will know where to go.

01:31:40And pay close attention to the direction of the waves.

01:31:42They are heading towards the shore.

01:31:44Also look at the sky.

01:31:46If you see seagulls

01:31:48or other birds, follow them.

01:31:50Sooner or later,

01:31:52they will lead you to the beach.

01:31:54The main thing here is the sun.

01:31:56It always rises to the east

01:31:58and sets to the west.

01:32:00At noon, it shines from the south

01:32:02located in the northern hemisphere.

01:32:04And located in the southern hemisphere,

01:32:06the sun is north in the middle of the day.

01:32:08Focusing on these signs

01:32:10will allow you to understand your position

01:32:12and to head towards the coast.

01:32:14But what to do if you still don't know

01:32:16which direction to take?

01:32:18Try to remember a morning in your hotel.

01:32:20Remember where the sun was

01:32:22For example, if you were on the balcony

01:32:24and you saw the sunrise

01:32:26on the right of your windows,

01:32:28it means you were facing south.

01:32:30In your boat, imagine the orientation of your hotel

01:32:32or your house relative to the morning sun.

01:32:34And head in that direction.

01:32:36Other signs can tell you

01:32:38where the coast is.

01:32:40If the water becomes muddy,

01:32:42it means there is the mouth of a nearby river.

01:32:44Move following this muddy water.

01:32:46A greenish hue in the clouds

01:32:48also indicates that the earth is close.

01:32:50So you drifted for several days

01:32:52and exhausted all your water reserves.

01:32:54At some point,

01:32:56you hear the cry of the seagulls.

01:32:58You open your eyes and you see them.

01:33:00You follow them and you notice muddy water.

01:33:02You are hungry, exhausted and thirsty,

01:33:04but happy

01:33:06because you know the coast is close.

01:33:08As the night falls,

01:33:10you see the lights of the city in the distance.

01:33:12In the morning, you reach the mainland

01:33:14and you return to the hotel.

01:33:16There are several ways to survive.

01:33:18The most important is to stay calm.

01:33:20Some people survived

01:33:22several weeks and even a year

01:33:24in the sea.

01:33:26Some floated on a broken ship,

01:33:28a pneumatic channel or the debris of a boat.

01:33:30But each time,

01:33:32the desire to live,

01:33:34the will and the hope helped them to hold on.

01:33:38Let's start with some crazy hypotheses.

01:33:40What would happen

01:33:42if we could miraculously visit

01:33:44each of our ancestors in chronological order?

01:33:46Could we talk to them

01:33:48and establish a real connection?

01:33:50And how long

01:33:52could we go back

01:33:54while keeping in touch with them?

01:33:56Well, let's see.

01:33:58The primates were

01:34:00the cousins of the other mammals.

01:34:04About 85 million years ago,

01:34:06during the period of the upper Cretaceous,

01:34:08they decided to follow their own path

01:34:10and became the first

01:34:12representatives of their species.

01:34:16Human evolution is very complex

01:34:18and we cannot trace

01:34:20distinct lines where it precisely began.

01:34:22But we will start with

01:34:24the Hominini.

01:34:26The Hominini are a group of primates

01:34:28that include all the species

01:34:30leading to Homo sapiens.

01:34:32Very well.

01:34:34Imagine that you have climbed

01:34:36in your super machine to go back in time

01:34:38and that you have landed in the past

01:34:40at the time when the Hominini

01:34:42roamed the Earth.

01:34:44You would notice these strange creatures

01:34:46walking around with their small velvet bodies,

01:34:48their puzzling faces

01:34:50and their big round eyes.

01:34:52They may seem a little different from us,

01:34:54but that's what makes all their charm.

01:34:56They were these excellent

01:34:58climbers, these incredibly

01:35:00curious people around.

01:35:02They enjoyed fruits, nuts

01:35:04and everything they could find.

01:35:06And yes, surprisingly, humans

01:35:08are not carnivores by nature.

01:35:10Originally, we were all

01:35:12vegetarians.

01:35:14Of course, with them you can make a cross

01:35:16on any form of adequate communication.

01:35:18But primates are

01:35:20particularly intelligent.

01:35:22So you just need to have some

01:35:24mime talent.

01:35:26Calm them down with friendly gestures

01:35:28and they will be delighted to meet

01:35:30a traveler of the future like you.

01:35:34These Hominini were

01:35:36curious by nature,

01:35:38so they would probably be very interested

01:35:40in meeting you.

01:35:44Let's move on to Homo habilis

01:35:46and Homo erectus.

01:35:48Their period, the Stone Age,

01:35:50began about 2,600,000 years ago.

01:35:52As you can guess,

01:35:54that's when we started

01:35:56using stone tools.

01:35:58This age lasted about

01:36:003,400,000 years

01:36:02and ended between

01:36:044000 and 2000 BC.

01:36:06It ended with the advent of metallurgy.

01:36:08Homo habilis,

01:36:10or the skillful man,

01:36:12was a bit like the Stone Age MacGyver.

01:36:14These ingenious creatures

01:36:16were the first to use

01:36:18stone tools.

01:36:20Homo erectus, for his part,

01:36:22was the man standing.

01:36:24His appearance is a little more recent.

01:36:26And as his name suggests,

01:36:28he was the first to walk on two legs

01:36:30like us.

01:36:32He certainly had a slightly different appearance

01:36:34than modern humans,

01:36:36with a bipedal look.

01:36:38So, what was he like?

01:36:40Well, we're talking about a real survivor.

01:36:42Homo erectus loved to explore the world

01:36:44and tinker with all kinds of things.

01:36:46He made rudimentary stone tools,

01:36:48like sharp stones to cut and scratch.

01:36:50He was essentially

01:36:52the first inventor in history.

01:36:54Homo erectus was also

01:36:56adventurous.

01:36:58He left Africa and traveled to distant lands,

01:37:00discovering new territories

01:37:02in the process.

01:37:04Homo erectus was one of the first

01:37:06to explore continents like Europe and Asia.

01:37:08He lived in caves,

01:37:10or simple shelters made of branches

01:37:12and animal skins.

01:37:14And let's not forget their innate sense of fashion.

01:37:16Their clothing was already

01:37:18made of skin and leaves.

01:37:24You wouldn't believe that they were walking

01:37:26on their thumbs all day long.

01:37:28They were hunter-gatherers,

01:37:30perpetually in search of juicy fruit,

01:37:32even killing some animals.

01:37:34How did they communicate with each other?

01:37:36Well, they didn't use simple gestures

01:37:38or body language

01:37:40to understand each other.

01:37:42So, if you met a Homo habilis

01:37:44or a Homo erectus,

01:37:46you would have a more muscular exchange.

01:37:48You could display our latest technology

01:37:50to amaze them

01:37:52and teach them new tricks.

01:37:54The next on our list

01:37:56are Homo heidelbergensis

01:37:58and Neanderthals.

01:38:00Homo heidelbergensis was, in a way,

01:38:02the older cousin of the Neanderthals

01:38:04and the modern man.

01:38:06He lived about 8 to 200,000 years ago.

01:38:08These men were strong

01:38:10and robust,

01:38:12with bigger brains than their ancestors.

01:38:14They were experts in

01:38:16tool-making

01:38:18and they always liked to explore new places.

01:38:22The Neanderthals lived

01:38:24in Europe and Asia

01:38:26between 400,000 and 40,000 years ago.

01:38:28They were very smart

01:38:30and remarkably well adapted

01:38:32to the cold weather.

01:38:34With their powerful body,

01:38:36their muscular muscles

01:38:38and their big noses,

01:38:40they could face the harshest winters.

01:38:42Homo heidelbergensis

01:38:44and the Neanderthal man

01:38:46were excellent hunter-gatherers.

01:38:48They hunted mammoths

01:38:50and other large carnivores

01:38:52by means of their own design.

01:38:54But they didn't care

01:38:56only about their survival.

01:38:58They also knew

01:39:00how to have fun.

01:39:02The Neanderthals had

01:39:04an artistic fibrousness

01:39:06and showed their emotions

01:39:08as well as their attachment to each other.

01:39:10With these guys,

01:39:12you would only have to draw pictures on the ground,

01:39:14dance and make gestures.

01:39:16They would surely understand the idea.

01:39:18And finally,

01:39:20here is Homo sapiens.

01:39:22Imagine this.

01:39:24You wake up in a cave with your family

01:39:26in the heat of a blazing fire.

01:39:28This cave is rather comfortable,

01:39:30isn't it?

01:39:32Except that this situation is not permanent.

01:39:34You are part of a nomadic tribe

01:39:36that moves where the food is.

01:39:38Well,

01:39:40but at least you have some ingenious tools

01:39:42to survive.

01:39:44So grab your superb handcrafted spear,

01:39:46made by observing the others

01:39:48or maybe your own crew.

01:39:50It's time to go hunt the mammoth.

01:39:52And if the mammoths

01:39:54are not cooperative,

01:39:56you just have to collect nuts,

01:39:58berries and eggs.

01:40:00The humans of the Stone Age were members of a gastronomic family.

01:40:02They knew how to make oatmeal

01:40:04and make it with wild onions

01:40:06and mustard seeds.

01:40:08There were also artists among them.

01:40:10Using mineral pigments and bones,

01:40:12they created superb paintings

01:40:14and even flutes

01:40:16to cheer up their campfire.

01:40:18You can always express yourself

01:40:20only by body language

01:40:22and facial expressions.

01:40:24But the Homo Sapiens

01:40:26were smarter than their ancestors.

01:40:28So we could teach them

01:40:30simple gestures

01:40:32and their meanings,

01:40:34like raising your hands to say

01:40:36mammoth or something else.

01:40:38Maybe try to perform

01:40:40a funny dance in front of them.

01:40:42It is certain to attract their attention,

01:40:44but it would not be the only way to communicate.

01:40:46The men of the Stone Age

01:40:48loved to draw and play music.

01:40:50So you would not have any trouble

01:40:52joining the party,

01:40:54showing your artistic talents

01:40:56with one or two sketches

01:40:58or whistling their few melodies.

01:41:00Do not worry,

01:41:02they will be impressed by your skills

01:41:04even if you are not much more talented than them.

01:41:06But tools are clearly

01:41:08the shortest way to their hearts.

01:41:10If you offered them some practical gadgets

01:41:12of our time,

01:41:14just create a simple tool

01:41:16able to make their life easier.

01:41:18And they will appreciate you instantly.

01:41:22So,

01:41:24even if you will probably not engage

01:41:26in a deep philosophical debate

01:41:28with these people of the Stone Age,

01:41:30you can still have a good time.

01:41:32Learning is the way to success.

01:41:34Moreover,

01:41:36even if life was shorter at the time,

01:41:38about thirty years on average,

01:41:40it was still long enough to find a partner

01:41:42or a progenitor.

01:41:44However,

01:41:46the options of meeting

01:41:48could be a bit limited.

01:41:50So let's leave this subject for another time.

01:41:52You will just have to hold your axe

01:41:54close to your hand during the night

01:41:56because, well,

01:41:58it was not uncommon for our ancestors

01:42:00to eat each other and cut each other.

01:42:02And that, it sucks.

01:42:04Let's finish our journey with the Bronze Age,

01:42:06just for fun.

01:42:08This period lasted from 3300

01:42:10to 2200 B.C.

01:42:12And guess what?

01:42:14The people of this time

01:42:16only swore by this solid metal

01:42:18called bronze.

01:42:20This is the time when we became creative

01:42:22and began to use this alloy

01:42:24to make all kinds of things.

01:42:26Bronze is a mixture

01:42:28of copper and tin,

01:42:30which makes it harder

01:42:32and more durable than anything else

01:42:34of this period.

01:42:36Formidable civilizations

01:42:38made their own bronze

01:42:40by melting copper

01:42:42and mixing it with tin

01:42:44or exchanging it

01:42:46with their neighbors.

01:42:48Thus, when you visit this ancient land,

01:42:50you will be amazed

01:42:52by the animated cities of the Bronze Age,

01:42:54adorned with massive metal statues,

01:42:56picturesque markets

01:42:58and grandiose temples dedicated to the gods.

01:43:00It was during the Bronze Age

01:43:02that we finally developed languages

01:43:04and writing.

01:43:06Mesopotamia and Egypt

01:43:08opened the ball with their

01:43:10wonderful cuneiform and hieroglyphic

01:43:12alphabets,

01:43:14the first writing systems ever invented.

01:43:16They were, so to speak,

01:43:18the kings of calligraphy.

01:43:20Remember that the language

01:43:22could be a little different,

01:43:24you would only hear unknown words.

01:43:26But with these humans,

01:43:28you can at least use drawings,

01:43:30singing and many other things

01:43:32to communicate.

01:43:34So,

01:43:36don't forget to cherish our past

01:43:38while appreciating the wonders

01:43:40of our modern world.

01:43:42Stay tuned!

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