The mathematics is my primary area of interest. Secondary is the Sumerian cultures and the mathematical information that seems to have been traded back and forth between the two civilizations. One of the more fascinating aspects is the Sumerian 6 x 60 x 60 x 60 subdivisions of a circle which seems to be part of that shared information. The Royal Egyptian cubit and Kings Chamber measures length and width are base in the radius and diameter of that 6 x 60 x 60 x 60 circle.
As said many times before, deciphering Ancient Egyptian structural dimensions requires at least a basic working knowledge of the their methods and demonstrated units of measure. We really are self imposing limited thinking when addressing their accomplishments by reverting to our mathematical methods for study of theirs.
Through the papyri the Ancient Egyptian present explanations accounting for what has survived in the arena of their largely ignored mathematics by researchers today. Their methods and explanations are evidently so at odds with our current system we ignore their methods which skews our current understanding of their system.
There are many plausible but unprovable conjectures along with some very foolish fantasies all of which are no substitute for good factual research. Ultimately it is evidence and understanding that separates plausible hypotheses from the unprovable conjecture and foolish fantasies. Fortunately all unprovable conjecture and foolish fantasies will eventually be abandoned and pass from scientific consciousness.
Your query regarding the Ubaid Cubit: I will have to plead ignorance, since truthfully I know little about the Ubaid Cubit. A quick search turned up little in the way of useful information. If the 72 cm measure is accurate the Ubaid cubit measures 28 1917/5000” and at first look, fractionally does not lend itself very well to the Royal Egyptian cubit. One thing I can state with certainty is all valid cubits lengths, relating to Ancient Egypt from the 18 inches of G1 sarcophagus to the 20 92/125 of G2 sarcophagus and up through Petrie Museum’s two 21 inch cubit rods all maintain a n/n-1 ratio to its predecessor and/or the Royal Egyptian cubit. This n/n-1 ratio is also found between the seked of the pyramids both interior passageways and exterior gradients.
LOL, I know the feeling you speak of. People, some like myself, have a tendency to shy away from responding to something they know little or nothing about. Others try to change the subject hence there is always a series of irrelevant responses.