- 21 minutes ago
Category
📚
LearningTranscript
00:00Υπότιτλοι AUTHORWAVE
00:30Υπότιτλοι AUTHORWAVE
01:00Υπότιτλοι AUTHORWAVE
01:30Υπότιτλοι AUTHORWAVE
02:00Υπότιτλοι AUTHORWAVE
02:02Υπότιτλοι AUTHORWAVE
02:04Υπότιτλοι AUTHORWAVE
02:35Υπότιτλοι AUTHORWAVE
02:39Υπότιτλοι AUTHORWAVE
02:41Υπότιτλοι AUTHORWAVE
02:43Υπότιτλοι AUTHORWAVE
02:45Υπότιτλοι AUTHORWAVE
02:47Υπότιτλοι AUTHORWAVE
02:49Υπότιτλοι AUTHORWAVE
02:51Υπότιτλοι AUTHORWAVE
02:53Υπότιτλοι AUTHORWAVE
02:55Υπότιτλοι AUTHORWAVE
02:57Υπότιτλοι AUTHORWAVE
02:59Υπότιτλοι AUTHORWAVE
03:01με την πολλή αυξησία του ανθρώπους.
03:11Νοηθούν Ελλάδα, 1948.
03:14Άρχεολογούς διαφηρετικά περισσότερα το σημαντικό τρίπος Ιόρφαρ,
03:18στον Νόρφαρ.
03:20Ιόρφαρ, τώρα, είναι αρκετά αρκετό αρκετό φαλό.
03:24Υπότιτλοι AUTHORWAVE
03:54Υπότιτλοι AUTHORWAVE
04:24Υπότιτλοι AUTHORWAVE
04:26Υπότιτλοι AUTHORWAVE
04:28Υπότιτλοι AUTHORWAVE
04:30Υπότιτλοι AUTHORWAVE
04:32Υπότιτλοι AUTHORWAVE
04:34Υπότιτλοι AUTHORWAVE
04:36Υπότιτλοι AUTHORWAVE
04:38Υπότιτλοι AUTHORWAVE, βρίσκονται από την μορφή.
04:43Υπότιτλοι AUTHORWAVE,
04:46και όταν αρχίζονται να προσφέρω το προσφέσιο δημιουργικό σχόλιο,
04:52δεν δημιουργείται ότι είναι μία από απλή,
04:56χρησιμοποιηθείς μόνος τεχνιστήριο.
05:00Υπότιτλοι AUTHORWAVE,
05:02Υπότιτλοι AUTHORWAVE,
05:05slower than that.
05:10The process starts off with the reduction of auntours.
05:15Then it look as if the frontal bones and the lower jaw and the lower part of the brain codes
05:21are removed carefully in very specific way.
05:24This is done by wrapping the bone they want to keep in clay.
05:27The skull is then heated in a fire.
05:29The exposed bone becomes brittle and can be broken off,
05:33And the process doesn't stop there.
05:36We get these holes, which are made artificially,
05:38in very selective points on the skull.
05:42It's done with a pointed stone or a flint axe perhaps.
05:47Each deer skull takes hours,
05:49even days of meticulous work.
05:52It's not a level of craftsmanship
05:54experts expect it to find on an 11,000-year-old site.
06:02Γιατί ήδη, ήδη, ήδη, ήδη, ήδη, ήδη, ήδη, ήδη.
06:08Η θερμή, ήδη, ήδη, ήταν στους 8 σκλούς αρκετά από την αρκετή.
06:14Ήδη, ήδη, ήδη, ήδη, ήδη, ήδη, ήδη.
06:17Παρ'ένα πολύ χρόνος να δημιουργήσει έναν ευκολογικό σχέδιο να κάνει με το χρόνο.
06:24Ήδη, αυτό πρέπει να ήταν σημαντικό για τους ευκολούς.
06:27Υπότιτλοι AUTHORWAVE
06:57την πρωτοβηλία αναγκρήσης να δίνει για το έργο να δίνει πρώτα να γυρήσει με τον παρόγου και να συμβαίνει το κόσμο ή να συμβαίνει με τον παρόγου.
07:08«Σιουλία από αυτά, λοιπόν, ειδικά το ένα κυριασμό ή νιώσιμο, όχι να δίνει τη στεγουρατητική θάλαση».
07:16Υπότιτλοι AUTHORWAVE
07:46Υπότιτλοι AUTHORWAVE
08:16Υπότιτλοι AUTHORWAVE
08:46One hint might come from Upper Paleolithic rock art recorded in the cave of Trois Frères in the Pyrenees.
08:53What looks to be a man wearing a deer suit, perhaps even in the course of transforming into a deer, or simply dancing wearing such a costume.
09:05Similar horned figures appear throughout ancient history, across many cultures, from Italy to Denmark and France.
09:16What are these monstrous figures? Are they connected to the Starkar skulls?
09:25The answer may lie in a more recent image of life on the Russian steppes.
09:29Half a world away in Siberia, an engraving from 1692, showing a man wearing a similar set of antlers.
09:38This image comes with a caption in Dutch, shaman or devil priest.
09:47It leads archaeologists to an extraordinary conclusion.
09:52The current thinking for the headdresses is that they represent one of the earliest examples we have in the archaeological record for a shaman's costume,
10:03which allows the wearer to transform their identity to become something which isn't perhaps all human.
10:11Something which blurs the characteristics of red deer and people together in an unusual way,
10:16and creates this cosmologically different kind of being.
10:21The presence of these skulls at Starkar, 11,000 years ago, suggests it's a center of shamanic religious worship.
10:32And they appear connected with other similar images scattered across Europe and Siberia.
10:41But Siberia and Yorkshire are separated by almost 4,000 kilometers of land and sea.
10:47Is a connection even possible?
10:51Or is this just a figment of overactive archaeological imagination?
11:05In 1931, a crew of English trawler men land an unexpected catch.
11:10A huge lump of what's known as moor log.
11:13So it's this big lump of wood that's been trawled from the bottom of the North Sea.
11:18And it's got mud and it's got bits of stuff stuck to it.
11:21And one of the things that comes off is this artifact.
11:25This spear point made from red deer antler, which is remarkably similar to many of the spear points we find at Starkar.
11:32But is that just coincidental?
11:38It's over 60 years before the apparent link between the moor log, the strange images scattered across the world, and the skull headdress becomes clear.
11:47It's only with the discovery of oil and the use of sonar mapping to really generate a high resolution understanding of what the bottom of the North Sea actually looks like,
11:59that we suddenly realize as archaeologists that there is this complete lost landscape there.
12:07Archaeologists discover a lost world.
12:10A rural Atlantis connecting Britain to continental Europe, now submerged beneath the North Sea.
12:16This European Atlantis is named Doggerland, after a famous seafloor mound.
12:23All of a sudden we have this data which is giving us an impression of this lost landscape.
12:27So valleys, riverbeds, estuaries, and miles and miles and miles of land which is populated by hunter-gatherers during the Mesolithic and the early Stone Age.
12:39How does this spectacular landscape end up at the bottom of the sea?
12:46During the Ice Age periods, when the ice is trapped in the caps, the level of the sea is lowered,
12:55and these shallow pieces of land that are just beneath the sea today are actually then exposed on the surface.
13:02They become vegetated, they get eroded by rainwater into rivers, and they become areas for settlements.
13:08And people move very quickly into these environments.
13:11And it means you've got direct communication between mainland Europe and Britain.
13:16Actually, not that long ago, 11,000 years ago, we were all joined up.
13:20This lost land bridge between Britain and Europe finally connects the dear people images across the globe with the headdress at Star Car.
13:33The large expanse of Doggerland allowed people to move around the wider European landscape.
13:39And if people are moving around, so are ideas.
13:41So, there is very little reason that the concept of shamanism, those kinds of ideas and those kinds of beliefs,
13:50couldn't have traveled with people across Doggerland and made their way to what we know as Britain today,
13:55at the time that Star Car is being occupied.
13:57The Star Car Skulls are not only proof of astonishingly ancient religious practices.
14:05They are also evidence that this 11,000-year-old spiritual culture is far more complex and widespread than we could ever have imagined.
14:20Some believe that shadows of these ancient shamanic rituals persist in our modern world.
14:25According to some legends, Siberian shaman were known to herd reindeer and deliver gifts at winter solstice in late December.
14:39And it has been suggested that this image persists today, in the story of Santa Claus.
14:47Maybe it's just a good story, or maybe there's something to it.
14:51In a German museum, sits a priceless and unique object.
15:07It looks like a modern emoticon, but it's actually an ancient artifact.
15:12Now, using the latest technology, we can reveal it in all its glory.
15:21The NEBRA Sky Disc.
15:24It's made out of gold and bronze.
15:27It's relatively heavy, and it's a very, very beautiful artifact.
15:32Really beautiful.
15:33Measuring roughly 32 centimeters in diameter, it's believed to be more than three and a half thousand years old.
15:42And on it is a series of what looks like astronomical objects.
15:48Possibly the sun, the moon, cluster of stars, and then it has some gold arcs.
15:53But could it be more than a piece of elaborate decoration?
15:57Does it mean something?
15:58Do the markings on the disc actually represent something?
16:03What looked like the sun, moon, and stars might make it one of the most ancient images of the cosmos ever.
16:10Nobody, not one archaeologist, would have expected such a find.
16:16Not in Egypt, not in Mesopotamia, and absolutely not in the heart of Europe.
16:22Is this the work of an advanced culture in the center of Bronze Age Europe?
16:27What do these symbols mean?
16:30Are they proof of some kind of secret knowledge?
16:34Or is this all just an elaborate hoax conjured up by looters?
16:39Because the discovery of the disc is a genuine, true crime story.
16:48It begins in May 2001.
16:52Archaeologist Harold Miller is shown a photograph of a Bronze Age horde.
16:57It includes chisels, swords, jewellery, and something he's never seen before.
17:06A strange disc decorated with gold.
17:09It appears to show on it the sun, crescent moon, a series of crescents, and then a series of stars all picked out in really vibrant gold work.
17:19It's completely unique in terms of the European Bronze Age.
17:23It almost defies belief as a find.
17:26It's really remarkable and it's really, really striking.
17:30On closer inspection, it seems to be more than just a pretty picture of the night sky.
17:35If you just have a general look at the disc, you see all these different symbols.
17:40But something stood out and it's a cluster of seven stars.
17:43Comparing the arrangement of these stars against known constellations suggests one strong candidate.
17:52It's thought that the seven stars represent an actual star cluster in the sky called the Pleiades.
17:56Meller realizes that if it is genuine, the disc represents one of the oldest images of the cosmos ever discovered.
18:07An ancient star chart.
18:10It was absolutely clear that this item, if it is really early Bronze Age, this would be one of the most important finds of the world.
18:20But in 2001, when Meller is shown the photo of this unique object, it isn't in a museum.
18:30It's for sale on the black market.
18:33I was really shocked.
18:35This crucial find was in the hand of looters.
18:40Shocked and angry because we can't touch it.
18:43We can't do research on it.
18:45If it goes to a private buyer, it could be lost forever.
18:49Believing it could be genuine, Meller tracks the stolen artifacts for months.
18:55In February 2002, posing as a buyer, he arranges a meet in a Swiss hotel.
19:03The man who had the disc had it in a towel under his shirt.
19:08So he opened the shirt and showed me the disc.
19:13But Meller hasn't come alone.
19:16As soon as the disc exchanges hands, the Swiss police pounce.
19:20The police do a very, very good job.
19:24And this was a really, really exciting police thing like in a TV thriller.
19:30Afterwards, the archaeologists and the police trace back the disc to two treasure hunters.
19:42They claim to have found the disc in the Siegelroda forest in Germany, near the tiny settlement of Nebra.
19:48And sold the horde to a dealer in Rhineland for over 10,000 pounds.
19:55They have no idea that the disc alone could be worth almost 700 times that amount.
20:027 million pounds.
20:04But its unique appearance and criminal origins make its authenticity questionable.
20:11Any such object that comes out of an illicit operation, a sting operation, also the art market,
20:19it is something that is very hard to determine if it is a fake object, if it is a hoax, or if it is a real thing.
20:25This is a fundamental problem that confronts Meller.
20:30So, is the Nebra Sky Disc an ancient artifact that could revolutionize our understanding of a lost culture?
20:36Or is it a fraud, cooked up by the criminal underworld?
20:44Now he's got his hands on the horde.
20:47Meller can finally try to get to the truth by figuring out how old the disc really is.
20:53But that's a tough ask.
20:55The dating of the Nebra Disc was complicated.
20:58It is unique.
20:59And once it is taken out of the layer of soil it rested in,
21:03you don't have that contextual information anymore about time, location,
21:07maybe the environmental conditions at that point.
21:11So, that is all lost.
21:13And because it's made of metal, we can't carbon date it,
21:16because it doesn't have anything organic to it to date from.
21:20So, we need to date it by association with the other objects that it was found with.
21:25It's not so easy to date the chisel and not so easy to date the arm rings,
21:32but it's really easy for archaeologists to date the swords.
21:35The style and how they were made pointed to a particular culture, the Unetis culture.
21:43And they were one of the first people in Europe to use bronze.
21:47From around 2300 to 1600 BCE, the Unetis culture occupies much of central Europe.
21:57This gives Meller a 700-year window for the age of the swords.
22:04And closer examination narrows the timeline further.
22:09He finds minute traces of wood.
22:12In one of the handles we found pieces of birch,
22:15and it was able to take a radiocarbon date from it.
22:18So, we know that the Horde was deposited around 1600.
22:251600 BCE is a perfect match to the Unetis culture.
22:31If it really is 3600 years old,
22:34the sky disk is one of the most ancient representations of the night sky ever discovered.
22:41Even older than any known Egyptian star chart.
22:45So, the archaeological stakes are high.
22:51But the only proof that the disk and swords belong together is the word of criminals.
22:57The swords were real.
22:59But the question is, was the disk really found next to the swords?
23:04How do we know that it's not something that's just been added,
23:07something modern, something fake,
23:09that's been added to an authentic collection of swords?
23:12One of the things that makes the disk look old is the green corrosion covering it.
23:19This green corrosion is called verdigree,
23:22and it's formed from copper, which is the principal component of bronze.
23:27And it's formed when that copper reacts with water and the atmosphere to create copper carbonate,
23:33which are these beautiful blue-green crystals on the surface of bronze.
23:37You see this greening on statues, like the Statue of Liberty is green for this same reason.
23:45A prominent German archaeologist suggests the disk's verdigree could have been faked using urine.
23:52To find the truth, scientists examine the disk using an electron microscope
23:57to measure the size of the disk's verdigree crystals.
24:01In a genuine artifact, what you see is a smaller number of very large crystals that have had that time to grow,
24:09whereas in a faked artifact, you'll see a much larger number, but of very, very small crystals.
24:15The verdigree crystals on the sky disk are small in number and large in size,
24:23and all of this is consistent with an artifact that has been lying around for around 3,500 years.
24:30So we know from these crystals that this isn't a fake.
24:34The science suggests the disk is so old it predates the reign of Tunangkama.
24:40But is it just ancient decoration, or is it meant to do something more practical?
24:48What is it for?
24:52One clue may lie in the decorative gold patterns.
24:55Experts suspect this cluster of stars are a depiction of a real constellation, the Pleiades.
25:03This might be significant, because the Pleiades are one of the constellations
25:07that we don't see throughout the year in the Northern Hemisphere.
25:10They appear around autumn time, around harvest time, and they disappear from view around spring.
25:17It might be showing when to plant crops, showing when to harvest crops.
25:21And the Pleiades may not be the only astronomical reference on the sky disk.
25:27Along one edge is a gold arc, and it's clear that there was once an identical arc on the opposite edge.
25:34If you take the location where the disk was found, they seem to match up with the position of the summer solstice and the winter solstice.
25:45So a difference of about 82 degrees.
25:47So it's thought that these arcs were used as a kind of measurement device that would allow you to work out what the time of year was based on the position that the sun rises on the horizon.
25:56The angles of the gold arcs could be coincidence, except for one rather incredible discovery.
26:04In 1991, a huge archaeological find was made, just 15 miles away from where the disk had been found.
26:15And it's a giant prehistoric earthworks, a structure that was probably used as some kind of astronomical calendar.
26:21Archaeologists uncover the remains of a wooden circular structure, roughly 75 meters in diameter, comprised of four concentric circles.
26:32A particularly important feature of Gossack Henge is two gates that are the same angle apart as those arcs on the sky disk.
26:40Gossack Henge is believed to date back to 4,900 BCE, over 3,000 years before the sky disk is created.
26:53It suggests that this is genuine astronomical knowledge, and it has been passed down for countless generations.
27:01And of course, it's not the only henge in existence.
27:04Perhaps the most famous henge in the world is Stonehenge in the UK, and its most famous function is that on the summer and winter solstices, the sun rises in a very particular position between the stones.
27:17Could all these similarities provide a clue to the sky disk's true purpose?
27:24Obviously, something like Stonehenge is not very portable.
27:26You can't exactly slip it in your pocket and make a few quick calculations about your crops.
27:29So, perhaps the Navras sky disk serves as a more portable, functional version of these giant prehistoric structures.
27:38What we see is scientists in these times.
27:41People who wanted to know something about the universe.
27:45The celestial calendar makes perfect sense.
27:49But it doesn't explain everything about the disk.
27:53Because there's a third golden arc, added sometime after the disk is made.
27:58And this can't be explained by an astronomical theory.
28:03So, what is it?
28:05One particular theory argues that this is possibly a sun barge.
28:11The idea of the sun traveling across the sky, or gods moving the sun across the sky, is one that's common to a number of civilizations.
28:20For the ancient Greeks, Helios, the sun god, would travel across the sky in a horse-drawn chariot.
28:26For the ancient Egyptians, the bark of Ra is a vessel which sails across the sky, carrying the sun god, Ra.
28:35But this motif also appears closer to home for the Unetis culture.
28:39On an artifact known as the Trondholm Sun Chariot.
28:46So, the Trondholm Chariot is a really fascinating and spectacular piece of material culture.
28:51It was recovered from a bog in Denmark, and it represents a chariot that's being pulled by horses.
28:57And in the back of the chariot, there is a gilded, golden, circular disc.
29:03A sun, effectively.
29:06Instead of a boat, the sun rests on a cart, pulled by a divine horse.
29:12It represents the eternal journey of the Nordic sun goddess, Sol.
29:16It's a really interesting example, and it's probably the clearest parallel we have for similar use of bronze to create these really spectacular artifacts,
29:27which link the sun and the movement of the sun within a kind of Bronze Age cosmology.
29:32The similarities with the disc seem clear.
29:36Experts believe this is the best explanation we have for the strange third arc.
29:41But could religious ideas from such distant cultures really have reached as far as the Central European Bronze Age?
29:54The answer may lie within the disc itself.
29:58If you look at the composition of a metal, particularly at the trace elements,
30:04those are the elements that are only present in really tiny quantities.
30:07They can give you a fingerprint about where that metal came from.
30:13So when they looked at the lead isotopes in the copper, which is the main constituent of the bronze,
30:19the lead isotope fingerprint matched a site on the far east of the Alps.
30:26With the copper pinpointed to the eastern end of the Alps,
30:30experts turn their attention to the other metals.
30:33What gives it its amazing features are the applied and the applications of gold on the surface.
30:43So the question was, where could this gold have come from that was used for the sky disk?
30:49The gold from the arc on the side of the disk is traced to the Carpathian Basin in Romania.
30:55But the gold in the sun, moon and stars proves harder to pin down.
31:02Dr. Borg samples and compares gold deposits from across Europe.
31:05Of something like 270 locations all over Europe that we had to exclude as a source,
31:13Cornwall is the only region until now that we have found where the composition of the gold matches the composition of the gold of the sky disk of Nebra.
31:24It's a remarkable discovery.
31:31The distance between Cornwall and the eastern Alps, where the copper is sourced, is well over a thousand kilometers.
31:38The sky disk of Nebra is showing us that the Bronze Age people were traveling across Europe at that time.
31:46They had trade connections.
31:48There was a united Europe already 1,600 years BC.
31:52Isn't that amazing?
31:54So the idea that religious beliefs about the sun could have been exchanged with the Unetis from widely separated cultures
32:01doesn't seem quite so hard to swallow.
32:05We may never know the full story of the Nebra Sky disk.
32:09Is it a spiritual symbol?
32:11A cosmic calendar?
32:13Or perhaps both?
32:16What the disk does show us is that ancient cultures that could easily be dismissed as primitive
32:22were, in fact, far more sophisticated than we had ever realized.
32:27What's absolutely incredible about this tiny object, whatever it really represents,
32:33is that it shows us that people, even thousands of years ago, were practicing astronomy.
32:38They were looking to the skies, they were understanding the movements of the sun and the stars,
32:42and how they related to phenomena that were happening down here on Earth.
32:45It really was one of the earliest true sciences.
32:51In the depths of London's science museum is a bizarre contraption from the late 1800s.
33:06It looks like a school science project gone wrong, but nothing could be further from the truth.
33:12This strange thing changes everything around us.
33:17There's almost nothing you see, hear, or touch that hasn't been affected by the development of this device.
33:27Now we can bring this antique to life once again.
33:32This is Fleming's diode.
33:35Standing just 22 and a half centimeters tall, it is a spidery gadget of glass and wire.
33:42You can see a wire filament and a plate embedded within a glass tube,
33:47and it's the combination of metals and glass that actually creates a very beautiful physical structure.
33:55When you turn it on, it seems to come to life.
33:59It has a beautiful property where it glows like an incandescent lamp.
34:04But it looks more like Dr. Frankenstein's idea of a light bulb.
34:08A contact pierces the glass bubble, connecting to a thin sheet of metal close to the glowing filament.
34:14It's designed simply to improve primitive radio.
34:21But it accidentally starts a world-changing technological revolution
34:25that's still going on today.
34:30Why is it created?
34:33How does it work?
34:35How does it end up transforming everything?
34:38In the second half of the 19th century,
34:46the first transatlantic telegraph cables connect North America and Europe.
34:51For the first time, nations can talk to each other instantaneously
34:56across thousands of kilometers of ocean.
35:00But this revolution has a weakness.
35:03It must be hardwired.
35:05Cables are expensive, prone to failure.
35:09And messages can only be sent between fixed points.
35:13Ships at sea, for example, are completely deaf and dumb.
35:18But in a German laboratory,
35:20a scientific experiment is about to spark a sea change.
35:24In 1887, physicist Heinrich Hertz uses a spark to generate electromagnetic waves,
35:33what will come to be called radio waves.
35:37These create a spark in a receiver half a meter away.
35:40There is nothing in between but thin air.
35:44It's like magic.
35:46The thought was that electricity required to flow through a wire.
35:50So this notion that we could actually have electricity flow without the wire
35:55was a completely new concept.
35:57It opens up a seemingly impossible idea.
36:01Communication without wires.
36:02But Hertz's scientific experiment only works over distances of a few feet.
36:12On its own, it will never change the world.
36:16One man more than any other transforms the dream of wireless communication into a reality.
36:24A young Italian engineer called Guglielmo Marconi.
36:29Over the next decade, he makes huge leaps in the evolution of radio.
36:33In 1899, Marconi's radio saves its first lives.
36:40A light ship in the English Channel transmits the world's first distress signal,
36:45alerting coast guards to a stricken vessel.
36:49But Marconi is thinking big.
36:52He wants radio to cross the Atlantic,
36:54and his receiver cannot detect radio over that distance.
36:58So he devises a more sensitive detector.
37:01But it has its own issues.
37:04It still wasn't quite perfect,
37:08because it was basically built on clockwork.
37:11Which means it has to be wound up by hand.
37:14And if the radio operator forgot to wind it up,
37:17of course the system wouldn't work anymore.
37:20Marconi wants to eliminate the mechanical element
37:23and critically improve sensitivity even further.
37:27Because more sensitivity equals more reliable reception.
37:31and a bigger range.
37:33Enter John Ambrose Fleming,
37:36a scientist working for Marconi.
37:38This spider-like object is what he comes up with.
37:46But how does this weird little contraption get the whole world talking?
37:53Fleming takes an entirely novel approach to detecting radio.
37:56His device doesn't just sense the radio signal.
38:01It manipulates it.
38:04So the way it works in a radio,
38:07when you receive a radio signal,
38:09the radio signal is going backwards and forwards,
38:11positive, negative, positive, negative.
38:12very, very, very, very, very rapidly.
38:14Thousands, tens of thousands,
38:16hundreds of thousands of times a second.
38:19This makes it impossible
38:20to directly measure the electrical signal from the aerial.
38:25Because the change of direction is so rapid,
38:27that the needle of any meter measuring it
38:29doesn't even begin to move before the current reverses.
38:33The needle appears stationary.
38:36So you cannot tell that there is a radio signal at all.
38:41Fleming's device,
38:42also known as a thermionic diode,
38:44solves the problem
38:45by chopping the radio signal in two.
38:49A thermionic diode
38:50allows current to flow in one direction,
38:53but not to flow in the opposite direction.
38:55When Fleming's device is fitted into the radio receiver,
38:59only the electricity flowing in one direction gets through.
39:03The needle doesn't get pulled back to zero
39:05by the reversing current.
39:07So the detector can register the signal.
39:10and a message sent from thousands of kilometers away
39:13can be received.
39:15But how does it pull off
39:17this strange trick with the current?
39:22The secret to the thermionic diode
39:24lies within the glass shell.
39:27Sitting in the vacuum
39:28is a thin filament that glows red hot.
39:32Close to it is a thin metal plate.
39:35The magic happens in the space between them.
39:37And it's all based
39:39on one of science's biggest,
39:42or rather smallest,
39:43discoveries of all time.
39:481897, Cambridge.
39:50The world of science is awash with new rays.
39:54Not just radio and x-rays,
39:56but a mysterious new one
39:58called the cathode ray.
39:59A physicist called J.J. Thompson
40:02was studying cathode rays.
40:05And what he discovered
40:06was that these weren't actually rays at all,
40:08but they were tiny, tiny particles.
40:11At the time,
40:12scientists believe
40:13there is nothing in the universe
40:14smaller than a hydrogen atom.
40:16But what Thompson finds
40:18is much, much smaller.
40:21These particles had a mass
40:23about a thousandth of a hydrogen atom.
40:26It's a scientific revolution.
40:30Atoms are no longer
40:31the smallest objects in the universe.
40:34And these newly discovered
40:36and mind-bogglingly small particles,
40:38named electrons,
40:40are the key to Fleming's device.
40:44It begins with the red hot filament.
40:47When you heat up the metal,
40:50the electrons effectively
40:52start boiling off the surface.
40:53Electrons are negatively charged.
40:57And Fleming's gadget relies on the fact
40:59that opposite charges attract.
41:02If you put a metal plate near it
41:05that's positively charged,
41:07those electrons are drawn off to it
41:09quite effectively.
41:11So you get current flow
41:13because electrons carry current
41:15and they're all rushing at this metal plate.
41:18But the current cannot flow the other way.
41:21If you swap the charges round
41:22and make the plate negative,
41:24the electrons wouldn't flow
41:25because they're negatively charged
41:27so they would be repelled from the plate.
41:29And that is how the Fleming valve works.
41:32What you end up with
41:33is a device that only allows electricity
41:35to flow in one direction.
41:39By the early 20th century,
41:41the radio signal that 25 years earlier
41:43leapt just half a metre
41:44now crosses oceans and continents.
41:51That's the problem
41:52Fleming's strange-looking glass spider
41:54helped solve.
41:55It was never intended to shape
41:57so much of the world we know today.
42:01Why was its impact
42:02so accidentally profound?
42:04It's the first electronic device.
42:09It's the beginning
42:09of the electronic revolution.
42:12Before that, we've got motors,
42:14we've got lights,
42:15we've got light bulbs,
42:16we've got switches.
42:17But essentially,
42:17you can turn things on and off.
42:20You can't really manipulate
42:22the way the current behaves
42:25in a complicated way.
42:29During the next decade,
42:31diodes grow a third wire.
42:32Now, tiny changes in the voltage
42:35of this third connection
42:36can change a large current
42:38flowing inside the device.
42:41It transforms these glass spiders.
42:45And what that is,
42:46is an amplifier.
42:48If you think about
42:48what you can do with an amplifier,
42:50before everything is dots
42:51and dashes in Morse code,
42:53now I can send speech,
42:56I can send music,
42:58I can make talking pictures.
43:01The movies talk.
43:02It has a profound impact.
43:06It becomes the foundation
43:08of much of the modern world around us.
43:11Television, computers, radios,
43:15mobile phones, the internet,
43:17it's all built on electronics.
43:20None of it could exist
43:21without electronics.
43:22The creation of this diode
43:26starts this electronics revolution,
43:28and that's a revolution
43:29that's still going on today.
43:31music plays in the background of the world.
43:34We'll be right back.
43:35We'll be right back.
43:36We'll be right back.
43:40We'll be right back.
43:52Υπότιτλοι AUTHORWAVE
Be the first to comment