(JimM) wrote in message om...

snip

The 2nd Law of Thermodynamics is in many ways the most fundamental law
of physics--indeed, of all science. No physical process can be
properly described without reference to it. If you do not know this
you are not much of a physist and should consider some other line of
work.

The 2nd Law says, among other things, that no machine (more generally,
no time-wise phyisical process) can ever be 100% efficient. A solar
sail is a machine. Ergo a solar sail (or indeed any mirror) cannot be
100% efficient.

The sail is "recoiled" * from sunlight, but the process is not 100%
efficient, and the light energy lost takes the form of heat. If
efficiency were too low, the sail would melt or evaporate.

In the light of above your description of what happens is nonsense. Go
back to Physics 101.

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Ok, here's a couple of problems I see. First, how can you describe all
physical observations in terms of the Second Law of Thermodynamics?
Ie, how does entropy manifest? Where do we get four dimensional space
from and other things that we observe in the real world?

Second, reviewing your comments, you seem to be implying that if one
were to construct a perfect reflecting surface, then it would not work
like an almost perfectly reflecting surface because entropy was
conserved. No momentum would be transfered to a perfect reflecting
surface while almost all of the momentum would be transfered to a
almost perfectly reflecting surface. But wouldn't it make vastly more
sense to treat the "perfect reflecting surface" as what it is. A model
which is the limit of constructable objects that do obey the Second
Law?


Karl Hallowell