Since I learnt, in Physics in the 3rd year at grammar school in 1945-46, about the behaviour of light waves, and why this explains the left-right reversal of a mirror-image, I have been exercised by the question as to why this side-to-side reversal does not also occur as a bottom-to-top reversal. The Physics teacher, one Mr Walters, was unable to explain this phenomenon to my comprehension; and many of my classmates agreed that they shared my puzzlement as to the reason.

Can anyone on Mudcat please explain, in terms sufficiently simple, not over-technical and non-mathematical, to be comprehensible to a scientific ninny like me, why this absence of up-down reversal when there is side-side reversal? Please!

~Michael~