Michel Fodje wrote:
> Dear Crystallographers,
> Here are a few paradoxes about diffraction I would like to get some
> answers about:
>
...
>
> 3. What happens to the photon energy when waves destructively interfere
> as mentioned in the text books. Doesn't 'destructive interference'
> appear to violate the first and second laws of thermodynamics? Besides,
> since the sources are non-coherent, how come the photon 'waves' don't
> annihilate each other before reaching the sample? If they were coherent,
> would we just end up with a single wave any how? With what will it
> interfere to cause diffraction?
>
For every direction where there is destructive interference and a
loss of energy there is a direction where there is constructive
interference that piles up energy. If you integrate over all directions
energy is conserved.
I'm not sure what your concern is about the second law. The radiation
is spreading out into space and so entropy increases.
Dale Tronrud
