Your uncertainty principle chimes with me, Donuel.

To revisit this, suitably stung by Stu's rebuke:

"To one of our ancestors standing by the bluestones it would appear totally mystifying, so how could this person explain their sighting of a helicopter to their family and friends? They can describe something but will not know what they were looking at all, and are unlikely to come up with the correct explanation at all."

Unfortunately, humans seem to suffer from a particular drawback of having such fine imaginations, that they are quite likely to come with an incorrect explanation. A really rational Stonehenge fellow might have worked at least something out about the helicopter. He might have seen an ash key taking much longer to reach the ground due to the rotation on its falling. Had he helped to trundle the bluestones from Preseli he might have articulated in his mind a connection between locomotion and the noise it generates. Feeling the wind from the blades he might have even realised that air was being pushed away and that that had something to do with the lift. After all, he'd seen plenty of birds in flight and seen the wing-energy they have to put in. He might even have felt the draught from a bird's wings as it passed him close. All that sounds a bit hard for our Druidic fellow, and it still wouldn't get him close to bearings, universal joints, compression and internal combustion. So, like the rest of us, he might have been inclined, had his rationality deserted him, to reach for a simpler, one-step explanation, that the flying monster had been sent by the gods to frighten him. I see a parallel there with the way that many people of faith will avoid the complexities of really trying to study all the facets of nature in order to get closer to the truth, settling instead for the most abject pseudo-explanation of all, that it was all just put there by God. That's all so easy but it's also an abysmal dereliction of intellect and it renders us vulnerable to exploitation and control. If a God really has made us to be so intelligent, he'd be a bit cross about that.