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# Re: [Phys-L] Refraction Implications

Yes, sure, the laser is measuring the slower travel time in water. I would guess Paul’s question boils down to this:

Would it be possible to have a model of light (obviously not the correct model) in which light bends toward the normal as it moves into a medium in which it travels faster?

I think there have been corpuscle models of light (maybe even due to Newton) along those lines.

On May 6, 2021, at 12:51 PM, Anthony Lapinski <alapinski@pds.org> wrote:

Neat video! I do a similar demo every year. I use a large playing card
taped to the back of a half filled (2.5 gal) aquarium. The card through the
water appears closer, and also why (full) swimming pools appear
shallower than they really are. Does the travel time have to do with the
speed of light being slower in water compared to air?

On Thu, May 6, 2021 at 12:36 PM Paul Nord <Paul.Nord@valpo.edu> wrote:

Paul

On Thu, May 6, 2021 at 11:31 AM Anthony Lapinski <alapinski@pds.org>
wrote:

Says video unavailable...

On Thu, May 6, 2021 at 12:27 PM Paul Nord <Paul.Nord@valpo.edu> wrote:

Two measurements of refraction give apparently contradictory results.

A parallax measurement from air into a denser refractive material shows
that distance to the back of the material appears to be shorter than
the
actual length.
A time of flight measurement of a laser pulse indicates that the
distance
to be back appears to be longer.

I made a video to demonstrate this:
https://youtu.be/JsoOlPpDv9l

Before you send me refraction diagrams, yes I understand that all of
these
observations are correct. Light slows down in proportion to the index
of
refraction. Light bends according to Snell's Law. I understand those
principles. Frankly, I'm enjoying the contradiction between the two
measurements above. Oftentimes at a point of contradiction like this
there
is a deeper understanding to be gleaned. Help me out there. To what
new

Paul
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