Re: [Phys-l] FW: Science show "Humanly Impossible" on NationalGeographic channel.

["John Clement" <clement@hal-pc.org>]

> Looks like a cool show, but they're wrong in the first minute or 2 of the
> human suspension preview. Pupils dilate to SHARPEN vision...? I like the
> use
Hmm, going back to the original quote, I assume it is a quote, what does it
mean?  If you use the word sharpen the way it is used in photo software, it
is edge enhancement.  One might think it means sharper focus.  But they are
probably just thinking of "it looks clearer" when you have more light.  With
more light you can see more shadow detail.  Incidentally most photo software
sharpens detail by making edges more distinct.  But there is some software
which actually does a deconvolution and refocuses the picture.  This has the
distinct difficulty that refocusing the whole picture may put other things
out of focus.

The problem here is that the "sharpen vision" phrase does not have enough
detail to figure out exactly what they are saying.  The full video may have
the necessary detail, but then again it may not.  This is a fairly typical
problem.  Students come into a science class throwing around ill defined
terms, and have difficulty in using precisely defined terms.  My favorite
example is that they use the phrase "straight line" as a synonym for
horizontal, but they also use it for a non curved line.  So if the answer
has to be a horizontal line, I will not accept "straight line".  Part of the
problem is bad linguistic habits, and part of it is they have not made sense
of a model.  There is also the factor that names are used as substitutes for
concepts.  So if you ask the meaning of something they give the name, rather
than explaining it.  After all names have magical powers!

So dilating pupils may allow you see things better in some fashion.  You
might even see more detail, but the actual focus might be poorer.  Of course
we love to pick nits on this listserv.

John M. Clement
Houston, TX