I am reminded of Galileo's supposed recant, the mutter translated as "and yet
it moves". Yes it does and it can be observed in specific circumstances.
When we setting the Ottoman sundial in St Louis I sensed I could see the shadow
move as we tracked the shadow against the scale. At the NASS conf
Im a little surprised at the hair-splitting responses regarding extreme
precision (Kevin was specifying 0.05 in/sec) and surface characteristics,
all of which are true, but missed the simple point of how large would the
dial have to be.
For a very rough first approximation, we know the shadow
Seeing a movement of the shadow is also dependent
on the surface on which you see the shadow. If
this surface is very even colored/structured it
will be more difficult to see a movement then
when the surface has such a structure (like fine
grain) that it is easy easier to see the movement..
T
Hi Kevin (and Peter R et al),
I saw your SML post and will watch with interest what responses it gets.
One point, though: the value of 1.27 mm/sec as the lower limit of perception of
movement is impossibly precise! I suggest that you would get +/-50% variation
between different observers. Also,
