okay so we're going for a ride around
the pyramids the Great Pyramid was the
tallest man-made structure for nearly
four thousand years only surpassed by a
large margin by the Eiffel Tower in 1889
one hundred and forty sevens meet up
sighs yeah its climate how much what
makes the pyramids even more impressive
is that these structures were built over
4,500 years ago when Egyptians didn't
have wheels or steel the only metal
available was copper and copper alloys
it took about two million stones to
build that pyramid well I call them
stones giant rocks somewhere between one
and a half pyramids took about 20 to 30
years to make it'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 three minutes if you consider
a regular work day like a ten-hour
12-hour workday nobody know how they
build it it's still secret but a lot of
people do try to do the best to give you
some information about how she did it
but we must say it's secret the date and
they take the signal of 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
bloss 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
the pyramid builders were not slaves at
all they were skilled workers
well-preserved tombs near the pyramids
suggest that their hard labor and
sacrifice were rewarded
if these workers have been slaves they
would not have received such honorable
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 a
hundred and seventy two men and that
that statue would have weighed somewhere
on the order of 68 tonnes 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 and he
wouldn't think that copper could really
cut rock but if you put an abrasive in
there like the sand you could actually
wear away the stone probably be a very
difficult and labor-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 as
one 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 a thousand
kilometers away from Giza and when the
now flooded water would come right
through here so that they could move all
the stones quarry adhere this granite
they could move this back up to Giza and
use it on the pyramids these would have
had to 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 seven
where diamond is a ten so how would you
dig a massive trench like that basically
the technique was just to smash the
dollar right rock into the granite over
and over and
over again they would make about five
millimeters 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 along straight ramp and
keep putting the rocks up I mean the
problem with that is the 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 pyramids 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 if you
can imagine that would be a pretty
spectacular site
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
on all of those 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 minutephysics Destin 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 check out
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 will be listening to
the brand-new audiobook 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 one 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 audiobooks so
if you love audiobooks then you should
definitely try them out so thank you for
watching and hopefully I will see you
next week