auto_transcript: mmm vision is arguably the most compelling
human sense words and stories and sounds allows to
imagine strange beasts and far-off worlds but seeing makes us truly believe they
exist and that's why we play so much effort
into correcting the optics our eyes when they don't work weather with glasses or contact lenses
or surgery but if you're in a pinch bleary-eyed or
missing your glasses there's a simple trick that will allow
you to see clearly just make a tiny tiny hole using your fingers look through it and the world will
become clear again this works no matter how bleary your vision is take after classes and
give it a try the mold the mold amazing right but to explain this was
retreat we just need to remember how seen works light to travel outwards from a source
bounces off objects its path travels in here I not here right now
where it forms an image if you're I had no lens light from a
single source would hit you right now in lots of places and result in a smeared out mass which
is exactly what happens when I think the lens of my camera on a lens focuses that spread out light
corralling it into a crisp image on your et non and after a little
excitation of light sensitive nerves and interpretation from your brain you see but wait when we look at an
object the background and foreground are usually blurry because a lens can
only focus light coming from one distance away if an object is to New Year more
too far its light will again be spread out on
your aetna leaving you with the blur fortunately muscles in our eyes allows
to a comedy by squeezing the lens which changes in spoke a link so we can
see a different distances except on weekends more when Ireland's
has become damaged in which case we need glasses unlike a lens pinhole or other small
opening can focus light coming from any distance because it's such a small opening it
only allows light to come through in one place and us in only one direction from any
particular source so there's no blurred everything is in focus if you're
familiar with the tiger feat this is why using smaller and smaller apertures
makes everything in your photo come into focus of course small openings like pin holes
and camera apertures create crisp images by blocking rather than focusing light to the images are much darker which is a
major reason why we use lenses rather than panels for glasses telescopes and eyes and yet in a pinch looking
through a tiny hole made with your fingers can help you see now do you see why
world the this video is brought to you in part
by Audible dot com the leading provider of audio books across all types literature including fiction non-fiction
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minute physics you can try out aloud by downloading a free audiobook at your
choice like the particle at the end of the
universe by my friend John Carroll who also raise an excellent blog about
his ex called preposterous universe the party going into the universe is
Sean's most recent book and it's about the search for and discovery of the
Higgs bows on I highly recommend it again thanks to
audible for helping me continue to make these videos and for giving you a free audiobook an
audible dot com slash minute physics well
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