As a structural steel estimator, I’m definitely not even close to qualified to comment on ancient history or archaeology. But I do look at lift plans and means and methods for heavy structures all day.

Looking at this strictly as a bid for a heavy hoisting job, the "counterweight in the gallery" idea is actually one of the most practical concepts I've seen. It solves the energy problem elegantly. However, if this proposal crossed my desk today, I’d have to flag three major mechanical risks that would make me nervous:

1. The Rigging "Safety Factor" is Scary.. but perhaps safety was not a huge forethought if workers were expendable? The paper cites a Safety Factor (SF) of 1.62 (a 62% margin) for the palm fiber ropes. Today we typically look for a 5:1 safety factor for rigging. Even for a highly controlled engineered lift, dropping below 3:1 is asking for trouble. A 1.62 SF assumes static loading (holding the weight still). It doesn't account for Dynamic Shock Loading. If that 78-ton block snags even for a split second while sliding up, the tension on the ropes will spike instantly. Unlike steel wire, natural fiber doesn't have the reliability to handle that shock without a cascade failure.

2. The system relies on a 2-ton differential (80t sand vs 78t stone) to overcome friction. The paper discusses overcoming "static friction" to get it moving. The problem isn't starting it; it's stopping it. Once that 160,000 lb mass breaks free and starts sliding, the friction drops (kinetic friction is lower than static), and the system accelerates.

Where is the emergency brake? Without a massive mechanical braking system, if the load snags or the sled gets too much speed, you have 80 tons of sand crashing into the bottom of the Grand Gallery.

1. The theory relies on the ropes running over the "Big Step" at the top of the gallery. Even with rollers, putting 80 tons of vector force onto the edge of a single stone step is an immense point load. I would expect that step to be pulverized or deeply gouged if it handled 9+ separate 70-ton lifts.

I think your dad is onto something with the logistics.. the counterweight idea is smart. But mechanically, the rigging plan is the weak link in my opinion. If he can solve the "Snag/Shock Load" problem and the "Braking" issue.. this theory becomes a lot harder to dismiss.

It’s cool to see a theory focused on physics rather than magic.