[jws]

Not passing the sniff test for me. Three flaws at first glance…

At the end he describes lowering blocks into place by incrementally removing bladders. This does not work. As soon as you are fully submerged and displacing with bladders you are unstable. As your depth increases, pressure increases, and your displacement goes down making you sink even faster. The good news is if you get neutrally buoyant you could poke the blocks down into place and they wouldn't weight much so you could move them around then remove the bladders.

Also not covered was how the water gets to the top. Each lock load of blocks and bladders requires at minimum the same mass of water to be lowered (to fill the lower lock chamber). In practice it will be at least several times this in order to keep the blocks from jamming in the chamber. So each ton of block effortlessly floated to the top will take several to many tons of water laboriously hauled to the top. Hauling water is probably lower friction than stone, compared to the volume multiplier, I can't say who wins.

The inner lower lock door is also a problem. It has to contain water at something like 10 atmospheres and be loose enough to move. Plus, if shaped like the video, it needs to weigh 150lbs/in^2 to keep from being blown out when raised. That makes it about 120 feet tall if made from limestone.

[ithkuil]

What if the channel was vertical an placed at the center of the pyramid?

     /| |\
    / | | \
   /  | |  \
  /===/ \   \

blocks surface at the center of the floor while it's being built.

The entering tunnel is gently sloped but doesn't have to reach the top of the pyramid.

I guess it would be easier to build since the the walls of the channels are kept in place by the weight of the whole structure.

I don't know about the bladders though.

[geuis]

Your sniff test doesn't matter. There was a recent episode of 99% Invisible talking about an architect in NYC who proposed building a skyscraper out of a steel internal skeleton but all the best engineers of the day scoffed at him. He built it, it still stands, and it changed out skyscrapers have been built since.

Point is, I'm skeptical too but the fellow has made some more videos that go into more detail. They even directly answer some of your questions.

Don't immediately write something off without doing some due diligence first. The more I'm learning about this, the more practical it seems.

[dobbsbob]

He explains it better in the second part, including how they got the water to the top, water pressure, water proofing ect. http://youtu.be/C1y8N0ePuF8 and of course in the actual book