Add scientific notes

[rrthomas]

The note from the start of Ch. 25 was removed some time ago (correctly, I think, as it seems to have been the only note in the book). It should be reinstated, and all the notes added from http://www.hpmor.com/science/

[domenic]

I'd strongly suggest putting them in an appendix though, and not interrupting the flow of the book between chapters. It's that kind of flow-interruption that I specifically want a nice eBook to avoid.

[rrthomas]

I agree, I was thinking of endnotes or footnotes.

[rrthomas]

The notes need to be updated and expanded for this to be worthwhile (there are broken links, for example).