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  • Ok, so we are going for a ride around the pyramids.

  • The great pyramid was the tallest man made structure

  • for nearly 4000 years.

  • Only surpassed by a large margin by the Eiffel Tower in 1889.

  • 147 metres high

  • You are interested by climbing?

  • Yeah! Let's climb it!

  • But is not free.

  • How much?

  • What makes the pyramids even more impressive,

  • is that these structures were built over 4500 years ago,

  • when Egyptians didn't have wheels or steel.

  • The only metal available was copper and copper alloys.

  • It took about 2 million stones to build that pyramid.

  • Well, I call them stonesgiant rocks.

  • Somewhere between 1.5 - 3 tons each

  • Pyramids took about 20 - 30 years to make.

  • That's a long time, but if you think about the number of stones,

  • a couple million stones in every pyramid,

  • you'd have to be laying a stone roughly once every...

  • 3 minutes.

  • If you consider a regular work day, like a 10 hour, 12 hour work day.

  • Nobody knows how they built it. Still secret.

  • But a lot of people just try to do the best to give you some information about how they did it.

  • But we must say it's secret.

  • The dead and the thing that sealed them. Nobody knows.

  • No plans survived to show us how the pyramids were built,

  • so perhaps it's not surprising that this is the subject of countless conspiracy theories

  • involving aliens, time travel, or lost technologies.

  • But there is a less far-fetched myth which has become widely accepted,

  • that the pyramids were built by slaves.

  • But recent discoveries suggest that the pyramid builders were not slaves at all.

  • They were skilled workers.

  • Well-preserved tombs near the pyramids suggest that their hard labour and sacrifice were rewarded.

  • If these workers had been slaves, they would not have received such honourable burials.

  • But how did they actually manage to build the pyramids?

  • One of the things I find really interesting is that the Egyptians didn't know about wheels,

  • so they didn't really even use rollers, as far as we can tell.

  • I mean, these rocks would have been carted across the desert on sleds.

  • There's a famous diagram of this giant statue being pulled by 172 men,

  • and that, that statue would have weighed somewhere on the order of 68 tons, or something.

  • This would normally create a lot of friction,

  • but the sand was wetted in front of the sled.

  • Experiments show this would reduce the pulling force required by half.

  • The internal stones of this pyramid are all limestone,

  • which is a bit softer and easier to work.

  • You can imagine them working it with those copper chisels that they had.

  • Some of these blocks may have been actually sawed through using copper saws.

  • Now you wouldn't think that copper could really cut the rock,

  • but if you put an abrasive in there, like a sand, you could actually wear away the stone.

  • It would probably be a very difficult and labour-intensive job.

  • Something that you don't really think about is that when you build a pyramid you need to build it on level ground.

  • You can actually see there how they had to level out that ground.

  • Well it's speculated that when the Nile flooded,

  • they put the flood water into a channel and see where the high parts were.

  • So the inside was made of this limestone. The outside of this pyramid was actually made of granite.

  • Much harder stone.

  • I'm at the granite quarry in Aswan

  • where they would have quarried the stones that were used in the pyramids at Giza.

  • Now that is an incredible feat because this is nearly 1000 km away from Giza,

  • and when the Nile flooded, water would come right through here

  • so that they could move all the stones quarried here,

  • this granite,

  • they could move this back up to Giza and use it on the pyramids.

  • These would of had to have been floated down on rafts.

  • Now quarrying this would have been really hard.

  • Granite is one of the hardest rocks because it contains quartz,

  • and quartz on the hardness scale is about a 7, where diamond is a 10.

  • So how would you dig a massive trench like that?

  • Basically the technique was just to smash the dolerite rock into the granite

  • over,

  • and over,

  • and over, again.

  • They would make about 5 mm progress per hour.

  • So there is no clear account of how the pyramids were actually built,

  • but the best guess is that ramps were used.

  • And in fact some ramps have been found on incomplete pyramids.

  • But you can't build just a straight ramp, a long straight ramp, and keep putting the rocks up.

  • I mean the problem with that is the ramp actually ends up taking up more material than the pyramid itself.

  • I think a ramp which sort of wraps around the pyramids is probably the most likely thing.

  • The top third of the height of the pyramid actually only accounts for about 4% of all the material in the pyramid.

  • That's why it's suspected that levers were actually used to finish off the pyramid, to do the top levels.

  • Now the pyramids have clearly weathered,

  • but in the past they would have been

  • a brighter white because they would have used a white limestone to cover the whole face of that pyramid.

  • And then the very top may have been covered with electrum,

  • which is a mixture of gold and silver,

  • so you can imagine, that would be a pretty spectacular sight.

  • The reason these pyramids are shaped this way

  • is so they represent sun rays.

  • Imagine what that would have looked like when it was first built:

  • With a shiny metallic top,

  • and smooth white finish on all of the sides.

  • I think that would have been a sight to behold.

  • Hey! I hope you enjoyed that video,

  • I filmed it earlier this year when I was in Egypt.

  • Now I'm currently in Melbourne, Australia and tomorrow I am flying to the US.

  • In fact next week I'm actually doing a live show in Alabama with Henry from Minute Physics,

  • Dustin from Smarter Every Day,

  • Brady Haran from Numberphile, Periodic Videos, and Sixty Symbols,

  • and CGP Grey from CGP Grey.

  • Yes, he will actually be there in person,

  • so if you want to come and join us, then checkout the link in the doobly doo.

  • You know on all of these long flights I always need something to help me pass the time,

  • and I know what I'm going to be doing tomorrow,

  • I'll be listening to the brand new audio book from Bill Nye.

  • The book is called Undeniable: Evolution and the Science of Creation,

  • and he actually narrates this book himself,

  • so I can't wait to listen to it.

  • And if you want, you can download this book for free by going to audible.com/Veritasium

  • or you can pick any other book of your choosing for a 1 month free trial.

  • So I really want to thank Audible for their support,

  • they've helped me go to all of these amazing places,

  • and they have hundreds of thousands of audio books,

  • so if you love audio books you should definitely try them out.

  • So thank you for watching and hopefully I will see you next week.

Ok, so we are going for a ride around the pyramids.

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How Were the Pyramids Built?

  • 1030 23
    luca3466   に公開 2017 年 06 月 16 日
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