On 3/18/2025 1:05 AM, Sylvia Else wrote:
https://www.youtube.com/watch?v=6dTyOl1fmDo
Too funny!
These "practical" examples (for some notion of "practical")
are always entertaining.
Hawkins' "Genius" series includes a number of such demos.
I particularly enjoyed the "time travel" episode and the
"self-assembling molecules" demo.
But, my favorite "in practice" example is the whispering
gallery at the Museum of Science and Industry in Chicago
<
https://www.msichicago.org/fileadmin/assets/_processed_/1/a/csm_whispering_gallery_exhibit_6ceb76f545.jpg>
(The *far* focus is just visible in the background)
(I imagine they exist elsewhere -- I can't recall if the Smithsonian
had one when I last visited. Grand Central Station also has one
but I don't think it was "by design"... more serendipitous)
[The Chicago museum is an amazing asset! A "must see" any time I had
guests in town!]
It is hard not to giggle as you encounter dozens of noisey tourists
walking all around you, talking loudly -- yet can hear your cohort
whispering ~20+ ft away, facing back-to-back!
When I was younger, I enjoyed seeing similar results in the design
of theatrical light sources (ellipsoidal, parabolic, etc.). But
they are nowhere near as dramatic!
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