Pete, I think you will find from what I wrote that we agree on the effective uselessness of germ-dancing, but I cannot agree with your apparent view of germs as being individually stamp-proof. True, only small fractions of our weight and momentum come to bear on a particular germ, but conversely, germs are small and delicate; it takes only a tiny force to squash, smear, or tear even quite a tough spore. Statistically, as you point out, a lot of germs under your boot simply will be protected by projecting parts of our footsoles and floors, but conversely, there is room for quite a lot of germs on the points, and those points are only a tiny percentage of the surfaces we walk on. Accordingly, they have to take very considerable forces, which is precisely why our soles and floors continually wear down as we walk on them. Any germ caught between two such abrading surfaces would behave much like a slug under the tyre of an accelerating car, or a mountaineer under a rock slide.

How can I tell, seeing that I never have trainied any microscope under my marching boots? Because I have seen what very modest forces will do to microbes under the microscopes. Also, in circumstances where germs are subjected to modest forces by fine-grained processes such as crushing them in powders to release their entrails for study, they really come apart under far smaller stresses than a skidding boot could apply locally.

Not that this has much practical significance as i march on of course; the interest is purely academic as I see it.

Cheers,

Jon