That thread was… interesting.
I quite likethe theory that the Egyptians discovered the secret of concrete before the Romans did.
Quite. At the very least, the pictures and diagrams in the video are hopelessly optimistic.
Stone is more dense than water (it sinks). Limestone has a specific gravity between 2.3 and 2.7 - which means that to float a block of limestone, you need to displace considerably more than twice its volume of water. You get 1 unit of that displacement from the block itself, so you need to add 1.3 or more units of extra volume.
Reeds have a density too (that is, they add weight as well as volume).
- so forget stone blocks with a little bundle strapped on the top and think stone blocks dwarfed by a bundle that is maybe twice the physical size of the block, or more.
…
But blocks were transported down the Nile by boat / barge. So the tower just needs to accommodate one.
Ancient Egyptians certainly had wheels, used in carts and chariots. Or did you mean wheeled vehicles capable of transporting the stones? And while pulleys are only attested from much later, they are believed to have been in use by 1500 BC (and possibly earlier) in Mesopotamia and therefore Egypt.
I don’t believe they had the wheel or chariots in the old kingdom period. IIRC, they got them during the Hyksos invasion in something like the 17-16th century BCE. Assuming my memory is correct that’s like a thousand years after the last big pyramid was constructed at Giza.
Yeah, that thread was certainly interesting. 
Sometimes I’ll still have a memory of the stinky footed Egyptians verse those chilling out under a tree with a drink in hand pulling a level to shoot blocks up to the top of the structure. And the whole ramps have been debunked thingy.
For the larger stones I’m guessing they got one stone per boat. So for the water assisted theory to work they would have to not only overcome the water-tight seal issues mentioned above but also build a chute big enough to accommodate the stone and the barge. That’s no small feat. There’s also the problem of designing and building a water containment system that would hold back the weight of all that water.
From a practical standpoint it won’t scale up and if it could be made to it would be a project that rivaled the pyramids themselves.
I’ve heard of this theory before. Assuming this isn’t a whoosh, to me the strongest evidence against it (aside from the quarried stones themselves) is that had they actually developed concrete they would have used it for all kinds of other things (roads, buildings and foundations, etc).
But that is the thing, the theory linked in the OP does not allow for a boat / barge to go up a tube. You have then a different idea. And as others pointed at other flaws, I have to notice the main historical one to that and the OP one.
As I noted on the GD thread, one big issue that an alternative theory has would be that no new evidence appears or is noticed that a new theory would lead one to find.
Here I’m referring, for example, to the traditional ramp / pulley main one, were there is evidence like the Anastasi papyrus making calculations about how to work with a ramp. Or discoveries that a new theory leads one to find, like the internal ramp theory where a notch in the pyramid can be explained by the new idea and it leads to the realization that the remains of an internal ramp can be found.
The problem with the water idea is clear then, indirect evidence regarding the Egyptians working the math about such complex hydraulics would be noticeable, or finding references of such efforts in the pyramids or the rocks around it.
As it is, I see that there is a lack of evidence, as others noticed likewise in the case of the ancient Egyptian obelisks too:
I’m not sure a lack of written evidence is necessarily compelling. Just look at the antikythera mechanism. No one had any idea whatsoever that such a device could have been manufactured when it was and as far as I’m aware, there is no documentation supporting the math or astronomical observations that went into its creation.
I thought wagons and carts predated chariots, dating to at least 2500 BC. For a chariot to work, you need a decently-sized horse, which is not required for a wagon.
If you have a cite that’s cool, but AFAIK even after the Hyksos invasion and the introduction of chariots carts weren’t used extensively in Egypt. And I don’t think they were used at all before the introduction of chariots in the 17th-ish century BCE. Could be wrong about that…they did have the pottery wheel after all, so they knew about it, and they did have donkeys (not sure about horses in this period…honestly can’t recall). I just don’t think they put them together, probably because the terrain favors the use of sledges over wheeled carts for ground transport and they have that big ass river to do most of the heavy lifting.
The device itself is the evidence.
There is a lot of speculation about methods to build the pyramids that aren’t backed up with any solid evidence. We haven’t found any water columns or seltzer geysers or ancient alien devices to support these ideas. The occasional scrap of stone that might possibly have been used for one of these innovative methods is not compelling evidence when there is no other evidence to back it up.
While, contrary to the assertions of some ruler of royal facades, there is plenty of evidence for the use of ramps, sledges and even lubricants in moving large stones in Egypt. There is even some evidence for the theory of hybrid ramp (i.e. a large ramp for part of the initial construction and internal ramps for the top) use in the largest pyramids at Giza. I like this YouTube video from Real Engineering that discusses this.
There is the mud ramp against one of the Pylon walls in the temple complex outside Luxor. (Plus, there are some unfinished columns. This was about 1,000 years after the pyramids, the Assyrians(?) invaded and the Egyptians buggered off in mid-construction.)
The problem with the theory is multiple -
First, as other mentioned, that’s a lot of water to haul to the top of the pyramid.
Second, the column is going to leak. So significantly increase the amount of water needed.
Third, once the column gets up past a certain point, the water pressure is going to be pretty serious. IIRC from scuba class, the pressure of water increases about 1atm -14.7psi - every 33 feet. The pyramids are several hundred feet high - 485 IIRC for the big one. A 165-foot column is going to have a pressure at the bottom trying to blow the whole thing apart from inside of 6x15=90psi. I would imagine the bottom half of the column would have to be made or weighted with big blocks of stone just to hold he top of the column on.
IIRC some rock came from nearby quarries, some of the rock for the pyramids came from across the way in the cliffs southeast of Cairo. If you go there now, you can visit the giant Coptic “Church in the Rock” in one of the hollowed out caves, but you have to go through Garbage City to get to it. (An adventure)
Finally, I think it was C.J. Cherryh on her website, while debunking von-Daniken type myths, mentioned they experimented with having the local high school football team dragging multi-ton blocks on skids. It didn’t take too many healthy strong young men to start hauling a block at a pretty good speed once they got it started. Using wood sleds, water and maybe milk for lubrication, I don’t suppose the Egyptians would have much difficulty moving big blocks either.
The general theory that makes most sense is the spiral ramp around the outside as the pyramid rose. (Lehner, The Complete Pyramids) This would also allow the workers the work surface from which to put the finished smooth stone (still visible near the top of the middle Giza Pyramid) as they removed the ramp. Plus, there is no evidence for a single, giant straight ramp (or any fanciful floating stone contraptions). It would be a monumental undertaking just to build a single giant gravel ramp - it would be as big or bigger than the pyramid itself, and in the days before dump trucks, just hauling that much crap away would be expensive, they would have left it nearby - and there’s no dumps of massive amounts of debris in the neighbourhood. A much smaller ramp at Masada took two years of slave labour. No, more likely they built a stepped out ramp of mud brick along the edge of the structure as it went up.
Just.
What is clear is that manpower was their greatest resource. The exact configuration of the ramps is not important to debunking extraordinary claims, they used ramps. They may also have used levers, they may have used log rollers, there’s no evidence of pulleys to provide a leverage advantage but I recall there was some supporting evidence that they knew how to use wooden rubbing blocks to pass a rope over the top of something and pull down from the other side (I don’t recall if there’s any evidence this technique was used on the pyramids but it seems readily obvious this was a better technique than pulling up on ropes). There’s no evidence of an external ramp either of any great height either, it would have been enormous and left a lasting mark on the landscape. Building such a ramp would have been almost as big of a project as building the pyramid anyway.
To be fair, they are proposing floats made of inflated animal skins. With a layer of reeds wrapped round them. Not floats made of reeds.
Not saying they are right, just playing Devil’s advocate.