Engineering principles (heuristics) were at work but not Physics (theoretical science).
Physics was not invented until the ancient Greeks, but the Egyptians certainly figured out some fantastic Engineering methods and invented the state of the art technology of the day, creating tools that we use even today in 2015.
It’s easy to mix up Science, Engineering, Technology and Mathematics. As an American, I’m embarrassed that we now have this thing called STEM which officially lumps them all together into a confusing ball of ‘something’.
Also, the “thousands of slaves” myth was debunked about 20 years ago if I’m not mistaken and current views of history do not include the 1960s movie style depiction of Pyramid building. I could be wrong though, so I’d have to check my sources.