
How many people did it take to build the Great Pyramid? - samizdis
https://spectrum.ieee.org/tech-history/heroic-failures/how-many-people-did-it-take-to-build-the-great-pyramid
======
burlesona
This is very cool to see. The main takeaways for me were:

1\. It's easy to underestimate what is possible when you limit thinking to a
short timescale. I think of the cathedrals, temples, mosques, etc. that have
been built all over the world, where the people who started the work knew they
wouldn't live to see it finished, but that didn't dissuade them.

Or conversely, it's easy to overestimate the difficulty of something if you
are too constrained by thinking in terms of finishing it relatively quickly.

2\. Building things does make it easier to build things - and conversely, not
building things makes it harder. There is a lot of architectural stuff in our
world today, particularly fine masonry and woodwork, that is still common
because so much of it was made up through the 1930's or so, but which is
actually quite difficult to produce today because most of the skilled labor
and the industry that supported it is gone.

This also reminded me of an article about scientific glasswork, which is
similarly dying out[1], and of course more familiar to the HN crowd we know
about old technology that was once common and now is difficult to replicate or
maintain.

Lots to think about.

1: [https://www.latimes.com/local/education/la-me-caltech-
glassb...](https://www.latimes.com/local/education/la-me-caltech-
glassblower-20160613-snap-story.html)

~~~
est31
There is a star trek episode where they encounter a civilization which has
built a benevolent AI a long time ago and has since lost capabilities to do
much more than give commands to the AI.

Our society has managed to write down some things like math for example so our
knowledge as species won't be lost if mathematicians suddenly died. But it's
harder to find permanent storage for the more skills based human activities
like the woodworking you mention.

To give another example, the Saturn V rockets were built by a generation of
metalworkers who had honed their skills in the manufacturing plants of world
war 2. The plans for the rocket engines are still preserved but back then a
plan was just a rough guideline. In the details, each single engine was hand-
tailored to the individual rocket. Nowadays, stuff is far more automated and
plans are highly precise. Thus Nasa couldn't just get the plans out of the
cabinet and build new Saturn V rockets or even just put their engines into new
rockets.

I wonder if we are better in preserving our heritage than we used to be. Which
information about the manufacturing process of one of today's cars will be
usable in 100 years? Will they be able to build computer chips like we did?

~~~
toomanybeersies
I don't know if NASA themselves could stick Saturn engines onto new rockets,
but I reckon the Air Force probably could. Air force technicians are pretty
good at fabricating and fitting parts from what I've seen.

Skills like hand fabrication and fitting aren't something that you can store.
You can record videos or interview skilled tradesmen as much as you want, but
the real skill is something that is learned through experience, it's muscle
memory and intuition, not theoretical knowledge.

~~~
weinzierl
I worked in aerospace during the transition from Ariane 4 to Ariane 5. The
Ariane 4 was a versatile modular launch system and widely considered a
successful project. The Ariane 5, on the other hand, was struggling at the
time. A large part was because it originally was designed to be a launcher for
the Hermes space plane. Hermes was never built, but the design decisions that
were made because of it had many negative consequences for the Ariane 5. Most
importantly it was not very economic for launching smaller satellites.

It was quite natural to think of enhancing the successful Ariane 4 design
instead of building Ariane 5. From the conversations I remember from that time
this was not considered a viable path - mostly because the supply chain of the
Ariane 4 parts had already gone dry and it was not considered realistic to
rebuild them.

For me as a young engineer this was very surprising, but a few years later I
understood two things much better:

1\. The knowledge to build projects of this scale is _very_ distributed. There
were subcontractors over subcontractors (spread over several countries) and
every one had some tacit knowledge viable for the project.

2\. Setup cost for parts production is relevant, even for the small series
productions common in aerospace.

------
habosa
That was definitely interesting but doesn't feel fully thought out. That's how
much energy it takes to move the blocks vertically into their position, ok.
What about horizontal movements to bring the blocks from the quarry to a
staging area to their final place?

Also there doesn't seem to be any consideration of logistics time. Were the
900 men always perfectly positioned to apply their energy to the project? Did
they not spend time and energy moving around the building site? Did they ever
make a mistake and have to redo a section?

This is a good starting estimate. As anyone who's ever worked on any project
knows, the estimate is going to be way too optimistic.

Also: I've been to Giza. It's hot and dry as all hell. Humans are going to be
far from perfect labor machines in that climate.

~~~
Balero
"Also: I've been to Giza. It's hot and dry as all hell. Humans are going to be
far from perfect labor machines in that climate"

The climate 4500 years ago was very different in this area, and the world in
general. For Egypt and the middle east it was generally a little cooler, but
much wetter.

When we are looking back into history, even only a couple of hundred years it
is important to remember that the climate, and geography was different.
Climate shifts, rivers and coastlines move etc.

~~~
close04
The analysis is only about the effort to lift one cubic meter of stone to an
arbitrary height a number of times until you reach the mathematical equivalent
of a "pyramid's worth", and then divide this by the average human work
capacity. That's it. No other theoretical or practical aspect was considered.
No friction, no logistics, nothing else.

The conclusion is that it took 900 men 20 years to lift one 2.6t cubic meter
of stone to a specific height again and again. Does anyone considers this to
be realistic for any construction project?

Like estimating the Mona Lisa took 5s to paint based on the surface of 0.4
square meters. Or the Sistine Chapel ceiling took a couple of days and a
really big brush.

The fact that someone with such a CV [0] came up with this for the IEEE page
as anything more than an exercise of imagination is very surprising for me.

[0] [https://spectrum.ieee.org/author/vaclav-
smil](https://spectrum.ieee.org/author/vaclav-smil)

~~~
scld
Well, the graph in the article says 3600 men for 20 years.

900 to lift the stones 900 to place and finish them (horizontal movement?)
1500 to cut the stone 3300 design/support (logistics?)

The details are below the fold.

~~~
close04
I'm talking about the details of the real work. The details of his results are
irrelevant since they're built from oversimplified assumptions. I mean the
author didn't even include friction in his calculations. Or placing blocks
with special shapes in exceptional positions. Or any setbacks, logistics,
infrastructure, trial and error, design revisions, human inefficiency,
illness, accidents, etc.

His calculations just say it probably couldn't have taken less. But more? Just
add a few more of those variables that he completely overlooked and the effort
easily increases by one order of magnitude. The worst project managers I've
met made better assumptions that this author.

You make bad assumptions you get bad conclusions. And saying them "with
certainty" just makes one sound even more ignorant. Imagine what his
calculations would say about La Sagrada Familia. Certainly not 150 years.

------
spyckie2
I love stuff like this.

I've always wanted to find a community that collaborates to determine as much
as possible the rough range of the total cost, either in man hours, dollar
amount or other metrics, of things we see, know, and interact with every day.
I think it is even more interesting if you try to estimate the cost of the
research the thing depends on (which greatly scales up the complexity but also
the fun of the exercise).

For instance, what is the manhour cost of google.com historically? You can
approach it in so many different ways - revenue analysis, # of employees in
google search team over the years, or just guess at how much you would need to
build google.com yourself today.

Subreddit suggestions for different styles of this kind of activity:

===

/r/resetPrice

Imagine that the infrastructure of the world has reset to the stone ages but
we still retain all modern knowledge. What's the price, in man hours, of
rebuilding things that we use every day and take for granted?

What is the reset price of google.com?

What is the reset price of Seattle?

What is the reset price of a mechanical pencil?

===

/r/CTMH

Cost in Total Man Hours

What's the CTMH of the NY philharmonic orchestra playing for one evening?

What's the CTMH of developing the entire iPhone phone line series, from
original to current model?

Also similar - /r/ETEB - Estimated total effort to build

~~~
strokirk
I really hoped those would exist! But they don't. :(

------
RcouF1uZ4gsC
> If a work year consists of 300 days, that would mean almost 18,000 man-
> years, which, spread over 20 years, implies a workforce of about 900 men.

While the analysis is interesting, I think the 300 working days a year is too
long. Likely, work on these types of public projects was mostly done during
the flood season, which was around 4 months (120 days [0]) so maybe 100 work
days at best, so the calculations for required workers should probably be
multiplied by 3.

0\.
[https://en.wikipedia.org/wiki/Season_of_the_Inundation](https://en.wikipedia.org/wiki/Season_of_the_Inundation)

~~~
lorthemar
Totally agree. I was searching for this comment. It's extremely unlikely that
a work year was 300 days thousands of years ago. But I don't think the workers
had weekends either. So, might be more than 100 days but still should be
roughly 3 times than the article shows.

~~~
onion2k
_I don 't think the workers had weekends either._

Weekends didn't exist until the Industrial Revolution, which was ~4300 years
after the pyramids were finished.

~~~
pbhjpbhj
Isn't the sabbath a "weekend"?

~~~
onion2k
I think the term 'weekend' has connotations of _not_ being religious, but
sure, maybe weekends were invented earlier than the Industrial Revolution if
the definition is generalized to 'a day when you don't work at the end of the
week'.

------
Areading314
This analysis ignores friction in the calculations for energy/manpower needed
to construct the pyramid. I wouldn't put much stock into these results

~~~
umvi
Yeah they just calculate the potential energy as if workers can move limestone
blocks with perfect efficiency in frictionless conditions. It wouldn't
surprise me if it took 2-4x its potential energy (or more) to move any given
block into place.

~~~
peeters
How many people does it take to push a two-ton rock up a hill and then back to
where it started? Apparently zero.

~~~
LanceH
The economist says that if you pay the rock enough it will move itself.

------
ncmncm
If they built the Great Pyramid in the advertised 20 years, that means placing
a 2.5-ton block every 4th minute, 24 hours a day, 365 days a year. If they
stopped at sundown, it's every 2 minutes. If they broke half the year to farm,
that's one each minute. But let's guess they had enough surplus to work year-
round; so, 2 minutes.

Suppose they took 600 years, instead; then it's one per hour.

Which is harder to imagine, cutting, moving, lifting and placing 30 blocks in
every waking hour for 20 years, or placing one per waking hour, non-stop, for
600 years? Each seems less possible than the other.

I don't know of any firm evidence for when any of the pyramids were built. We
can _guess_ that the bent and red pyramids were built first, but they could
just as easily be poor copies attempted a thousand years later, or ten.

There is a fluorescence technique to discover when a cut limestone face that
has been covered for centuries was last exposed to sunlight, but I don't know
of it being used on any Great Pyramid block. One would not expect
Egyptologists to advocate for such a test, because only two outcomes are
possible: they were far enough off to be embarrassed; or not, and it was
useless. (Either way, better not.)

They built these things with perfectly straight, slanting tunnels a few inches
wide running from inner chambers almost to the surface, for no known reason.
Some people say they point at certain mythologically important stars on
equinoctal days, but I have not been able to get confirmation of that.

One thing well established is that none of them were tombs. When somebody
finally battered their way into each, maybe 4300+ years later, all the
chambers were empty and unmarked. (Except one has an empty stone box in it big
enough to be a coffin or bathtub.)

There are lots of examples of 20-, 30-, 60-ton basalt boxes cut from living
rock with perfect right-angled inside corners, and moved through funerary
complex tunnels barely big enough. Take off the (10-ton) lid and they're
empty. It's anybody's guess what they were for.

~~~
idoubtit
Parallelization is not a concept that appears around 2010 when low-end
computers gained multiple cores. Most of the blocks were at the bottom levels,
where it was easy to put them in place. Teams moving hundreds of blocks
simultaneously wouldn't be surprising. This addresses the first point, and I
don't want to react to what follows, especially the theory that all
archaeologists are in a conspiracy to hide the truth.

~~~
ReptileMan
The hardest part for me is the engineering of the building. The quarywork and
positioning is a matter of having enough labor, carrots and sticks.

But to imagine, make plans, adhere to them is hard.

------
stormdennis
When King Edward I, suppressed the NW of Wales he had four large imposing
castles built in a short period of time to dominate the region. Two of them
were completed in less than a decade and work on the other two was started.
They are still there to this day and are probably the most impressive
structures in the region

~~~
buro9
[https://cadw.gov.wales/visit/best-history/castles-and-
town-w...](https://cadw.gov.wales/visit/best-history/castles-and-town-walls-
edward-i)

------
close04
This is almost the literal exemplification of the classic "if 1 woman takes 9
months to give birth to a baby, 9 women will do it in a month". The math is
interesting and a fun exercise of imagination. But it ignores so much and
oversimplifies that it shouldn't really be seen as anything more than "fun".
Which is still fine for an article that took no more than 25 minutes of work
based on word count and expected typing speed.

------
Cactus2018
I recently learned about the highly polished white limestone 'cladding' or
'casing' stones

Wikipedia says:
[https://en.wikipedia.org/wiki/Great_Pyramid_of_Giza#Casing_s...](https://en.wikipedia.org/wiki/Great_Pyramid_of_Giza#Casing_stones)

> Casing stones

> At completion, the Great Pyramid was surfaced with _white "casing
> stones"—slant-faced, but flat-topped, blocks of highly polished white
> limestone_.... Visibly, all that remains is the underlying stepped core
> structure seen today.[citation needed] In 1303 AD, a massive earthquake
> loosened many of the outer casing stones, which in 1356 were carted away by
> Bahri Sultan An-Nasir Nasir-ad-Din al-Hasan to build mosques and fortresses
> in nearby Cairo.[citation needed] Many more casing stones were removed from
> the great pyramids by Muhammad Ali Pasha in the early 19th century to build
> the upper portion of his Alabaster Mosque in Cairo, not far from
> Giza.[citation needed] ...

------
buran77
> we can say with some confidence how many people were required to build it

When someone claims that "by appealing to simple physics" they can say "with
confidence" how many people were involved in a construction from almost 5000
years ago I have to doubt anything that follows is more than pure speculation.

The problem is too complex for simple physics to provide any relevant answer.
The same simple physics would have us believe 14000 strong men could throw a
tiny 1Kg object straight into orbit.

------
octabond
You are assuming optimal efficiency for each human.

Don't think that was the case

~~~
SideburnsOfDoom
Right. Energy analysis is cool, but it places a lower bound on the amount of
work needed, that's all.

If you're only counting energy needed to raise stones, then you're costing at
zero a piece of stone, cut and transported to ground level near the pyramid.
But that is hard work.

------
westurner
> _The potential energy of the pyramid—the energy needed to lift the mass
> above ground level—is simply the product of acceleration due to gravity,
> mass, and the center of mass, which in a pyramid is one-quarter of its
> height. The mass cannot be pinpointed because it depends on the specific
> densities of the Tura limestone and mortar that were used to build the
> structure; I am assuming a mean of 2.6 metric tons per cubic meter, hence a
> total mass of about 6.75 million metric tons. That means the pyramid’s
> potential energy is about 2.4 trillion joules._

In "Lost Technologies of the Great Pyramid" (2010) and "The Great Pyramid
Prosperity Machine: Why the Great Pyramid was Built!" (2011), Steven Myers
contends that the people who built the pyramids were master hydrologists who
built a series of locks from the Nile all the way up the sides of the pyramids
and pumped water up to a pool of water on the topmost level; where they used
_buoyancy and mechanical leverage by way of a floating barge crane_ in order
to place blocks. This would explain how and why the pyramids are water tight,
why explosive residue has been found in specific chambers, and why boats have
been found buried at the bases of the pyramids.

[https://www.amazon.com/dp/B0045Y26CC/](https://www.amazon.com/dp/B0045Y26CC/)

There are videos: [http://www.thepump.org/video-
series-2](http://www.thepump.org/video-series-2)

[https://www.youtube.com/playlist?list=PLt_DvKGJ_QLYvJ3IdVKXU...](https://www.youtube.com/playlist?list=PLt_DvKGJ_QLYvJ3IdVKXUUIZAsX0_QD-4)

I'm not aware of other explanations for how friction could have been overcome
in setting the blocks such that they are watertight (in the later Egyptian
pyramids).

AFAIU, the pyramids of South America appear to be of different - possibly
older - construction methods.

------
utopcell
Ahem.. I'm just going to drop this link here on how the pyramids were _really_
built: [https://youtu.be/TJcp13hAO3U](https://youtu.be/TJcp13hAO3U)

~~~
jiggawatts
That's rather... imaginative.

Certainly, water played a role: much of the stone was shipped from quarries
some distance away.

It's also imaginable that they used canals to bring the blocks further inland,
closer to the pyramid construction site.

However, the near-vertical water tower and lock system would be a challenge to
build today, let alone with the technology of the era. The pyramids were built
before the widespread use of the _wheel_ , and with soft copper tools, not
bronze. They predate the invention of _nails_ , as in the type used to join
wood. For example, the planks of Khufu's ship were bound together with knotted
ropes and its sails were moved without the aid of block and tackle, as this
would have required wheels and axles! It's a sight to behold...

~~~
noneeeed
That was really interesting. Itr's weird to think of how many mundane
technologies actually had to be invented, and how things would have worked
before. The idea of a boat built without nails is kind of crazy.

~~~
jiggawatts
Bizarrely, for me, seeing Khufu's ship in person was far more memorable than
the pyramids themselves. The pyramids are just... piles of rock. Sure, they're
big and impressive, but no more. Without using your imagination, you can't see
how they were built, what life was like at the time, or what the technology
was like.

The ship was incredible, to my eyes at least. My partner wasn't interested,
but she never studied engineering! To my eyes it looked almost modern, yet
absolutely bizarre to the point of being nearly alien, but only in the
_details_. The joinery. The rope work. Things like that.

I liken it to seeing a jumbo jet fly over for the first time. It's huge and
impressive, like the pyramids. But to me, seeing an _airport_ was the real
wonder. All those planes with the engine nacelle covers open, showing the
intricate tubing and turbine housings. The bizarre low trucks and specialised
equipment that's used nowhere else. The fuel pump trucks that suck up jet fuel
from underground pipes. The strange land of endless concrete. People waving
glowing sticks. And so on and so forth. It's an entire "world" that's
different from the normal world outside. You get to see the inner workings of
the technology up close, not just a superficial end product from a distance.
That's what it felt like to see Khufu's ship for me. I felt like I had stepped
into the era of the Pharaohs.

~~~
noneeeed
On a smaller scale, that reminds me of the clock at Wells Cathedral
([https://collection.sciencemuseumgroup.org.uk/objects/co1347/...](https://collection.sciencemuseumgroup.org.uk/objects/co1347/wells-
cathedral-clock-clock)) for 1392. The Cathedral is a great example of its
kind, but for me the clock was a lot more interesting. Although that might be
bacause I've been to dozens of medieval cathedrals so they do kind of blur
into one.

I'd like to visit the Pyramids, but I'm more interested in the insides.
Khufu's ship sounds fascinating, will definitely take a look if we go.

~~~
jiggawatts
That style of clockwork reminds me strangely of the Doctor Who episode The
Girl in the Fireplace (1), with the clockwork robots, which in turn is the
same kind of "odd" feeling I get from Khufu's ship, or steampunk in general
(2).

1)
[https://en.wikipedia.org/wiki/The_Girl_in_the_Fireplace](https://en.wikipedia.org/wiki/The_Girl_in_the_Fireplace)

2) [https://i.imgur.com/eSsrlSh.gifv](https://i.imgur.com/eSsrlSh.gifv)

------
quxbar
This is great! Begs the next question - how efficiently did the Egyptian
government organize labor?

~~~
Fjolsvith
They hadn't invented unions at that time.

~~~
pbhjpbhj
Was Moses the first recorded union rep? A plague of frogs is one up on work-
to-rule.

~~~
Fjolsvith
I don't think so. The pyramids were built between 2589 and 2504 BC, while
Moses wasn't born until 1393 BC.

------
onion-soup
Now divide total number of blocks by 30 years and you get 1 multi ton block
being laid every 9 minutes.

The current theories are joke, this numbers don’t add up. Don’t be afraid to
challenge the “academic” theories, as you see, there is no math behind them.

~~~
Mirioron
I hear you!

Combining your results with the scientists' we can only conclude that the
Ancient Egyptians had some technology available to them that has been lost to
time. Even modern cranes can't do that. Therefore the only other option is
aliens!

------
8bitsrule
I'd be interested in seeing whether some of the new dating methods could be
used to scientifically date the Pyramids. Because there's more than one reason
to think it might be -a lot- older than 4,600 years ... an anecdotal number.

For one easy reason, you don't just build one from scratch without a lot of
experience. A lot of artifacts of that period are -way- too impressive for the
same reason. Where's the evidence for prior art of that calibre?

And when will the chemistry of the blocks be analyzed? Were they cut (how) or
manufactured (how)? I haven't seen the book delineating these studies; if it
doesn't exist, how long should the present fairy tales?

~~~
RcouF1uZ4gsC
> For one easy reason, you don't just build one from scratch without a lot of
> experience. A lot of artifacts of that period are -way- too impressive for
> the same reason. Where's the evidence for prior art of that calibre?

Snefru, who was the Pharoah before Khufu (which is the one that build the
Great Pyramid) provides a nice example of failure and progression.

He first started with the Meidum Pyramid. This pyramid collapsed during
construction.

The he did the Bent Pyramid. This is like it's name in that the angle changes
as you go up the pyramid.

Finally, he did the Red Pyramid which looks like what we think of when we
think of a pyramid.

So yes, even right before the Great Pyramid, you can see evidence of a
learning process.

This article,
[https://en.wikipedia.org/wiki/Sneferu#Building_projects](https://en.wikipedia.org/wiki/Sneferu#Building_projects)
provides a nice summary with pictures.

~~~
ncmncm
It is plausible that these projects were done first. It is equally plausible
that they were clumsy attempts to copy the big guys, a thousand years after.

The closer you look at the evidence, that far back, the more slippery it gets.
Tour groups want a nice, simple story, and the pros are happy to provide one,
but the support is very limited, subject to interpretation, opinion, out-and-
out guessing, and fraud.

------
blackrock
It must’ve been built by aliens. Since we can’t figure out the math behind it.

Some inner chambers seems to point at the Osiris star cluster.

Kidding..

I wonder if an ancient engineer discovered a more useful purpose for the
pyramids. Like channeling salt water into the chambers, to create a battery
somehow, in order to create an electric field, which was used to power some
kind of light bulb at the top. So the pyramid ended up becoming some type of
light tower, to illuminate the darkness. This indeed, would be fascinating
stone aged technology, that can last for a few millennia.

Note, we can’t find the light bulb at the top, to support this fictional
theory, because it got looted at some point in history. Maybe it was a
precious diamond or something. LOL..

