Polarization by Scattering, and Fishtank Sunset

Simulation of atmospheric scattering and polarization of sunlight using a slide projector and an aquarium containing milky water. In the first part of the demo, we use an angled mirror to show the effect of a polarizer on light scattered from the side of the tank vs from the top of it. In the second part, we show how Rayleigh scattering makes the sky blue and sunsets red by gradually adding more milk to the water in the tank.
For more details on our setup, see
sciencedemonstrations.fas.har...
Thanks for watching!

[@robertpitt8418]

This has been a very thoughtful video for me : thank you so much

[@mohamedelouadghiri2016]

light phenomena are very amazing

[@10thmanrising8]

Very interesting Flatzoid... gives a whole new perspective

[@manudehanoi]

had no idea about the polarization thanks for this great vid

[@El3ctroG3ist]

Amazing!

[@NatSciDemos]

Thanks!

[@beachboardfan9544]

So milk in the atmosphere is responsible for the yellow sun and blue sky?

[@Bigvs.Dickvs]

Yes, it's the milk from the Milky Way.

[@beachboardfan9544]

@@Bigvs.Dickvs 🤯

[@robertpitt8418]

@@Bigvs.Dickvs o my goodness you are amazing - there is chemistry bhind each object-ive - naming

[@theubercaste]

I thought that too

[@JaspreetSingh-hf3rz]

I cannot stop laughing😂😂😂

[@am-lr9wr]

على الفطرة

[@Rasayana85]

What would happen if you had milk in a concentrated sugar solution, and matched the vertical and horizontal path-lengths to plane polarizing filters for the exiting lights? Would you get different colors due to circular dichroism? Well... for some arbitrary rotations of the exiting filters, you absolutely would, but what rotation would you set the filters if you were guessing for the same exiting wavelength?

[@AdityaMehendale]

Interesting experiment; would have been a wonderful demo indeed. The periodicity of the dark/light bands changing as a function of the concentration of the sugar.

[@dalegriffiths3628]

@NatSciDemos - Nice, given the size of the casein particles is this Rayleigh or Mie Scatteirng?

[@NatSciDemos]

The average diameter of milk casein is about 150 nm, which is why works well for showing Rayleigh scattering.

[@AdricM]

sunsets with a lot of ash in the air are quite red.

[@AdityaMehendale]

Some background-theory would have been helpful. Also, I was half expecting a demo where the polarizer is rotated in place with the light passing through it the whole time..

[@horizontal120]

so what you saying is that there is milk in the sky ? :D

[@Bigvs.Dickvs]

Like love, the Milky Way is all around!

[@glaucomflecken]

Why does it not rain milk?

[@manudehanoi]

is the scattered light polarized too ?

[@NatSciDemos]

Yes the light scattered from the side of the tank is completely vertically polarized, and from the top it's completely horizontal. So when we filter out the vertical component coming from the projector, no light is scattered from the side of the tank because the milk particles are no longer being driven and re-radiating in the vertical direction; meanwhile, the horizontal component coming from the projector is not filtered, and so the horizontally polarized re-emission from the scattering particles is unaffected.

[@stainlessstuff]

@@NatSciDemos very interesting, that means a dipole vibrating vertically will radiate horizontally. btw I'm consfused about the wavelength dependency in the link given in the description , the milk particules diffract selectively the blue meaning they are near the blue wavelength size ? That seems very small for milk particle

[@NatSciDemos]

The casein micelles found in cow's milk can be hundreds of nm in diameter, with the average estimated to be about 150 nm (dx.doi.org/10.5772/62779), which is just off of the blue end of the visible spectrum.

[@realist3040]

Milk is very good :D

[@glaucomflecken]

A glass of milk a day, keeps those people away...

[@maxcompress9732]

00:22 it's already blue before adding milk.

[@NatSciDemos]

yeah, the water and tank were not perfectly clean, so there was a little scattering going on even before adding the milk

[@rmbf57]

Pensé que iban a mostrar las variedades levógira y dextrógira de la misma sustancia :vvv

[@glaucomflecken]

But why is the earth flat?

[@Bigvs.Dickvs]

Because of the celestial effect of the Great Dish Of Milk from the Milky Way.
TLDR: _Because_

[@glaucomflecken]

@@Bigvs.Dickvs where does this milk come from? Whose milk is this? Is it pasteurised and is it safe to drink?

[@rmbf57]

But if You use goat milk, You Will have an eclipse! Xdxdxddd

[@theubercaste]

2:53- looks like a chem trail day.

[@robertpitt8418]

scientifically engineered artificially created sun moon and stars above the sealing

[@marcinhoplim]

Little I know you can put some milk in your fishtank so fish can have a sunset.
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edit: kidding!

[@lekunberriko1]

Quítate la máscara, hombre.