Only some humans can see this type of light

thanks to the brilliant organization for supporting PBS Digital Studios. I'm here in Los Angeles with my friends William Osmond and Alan Pan. You guys are going to make

some

art here to decorate with strips of tape. This really cheap clear tape, okay? I want a lot of overlays for you I'm overlaying a lot of mine it looks like you have a pretzel stick with major problems with the songs I don't know what's going to happen here but now you're exciting me

this

piece has Alan's hair In it you see the long bevel . Hermione is not happy with Ron and Harry right now.

Go ahead and look through your artwork at the

light

. It looks like I can see that there are a lot of fingerprints because I like things like little circles. Well, nothing. these are our polar ice caps now hold

this

behind put this front wow these colors there is no tournament like spin oh the colors are changing it's like I love this demo okay just to clarify you can do this demo in different Behind the plastic with the tape you can put an LCD screen or one of the polarized sheets and then in front of the plastic you can use polarized glasses to look at it or you can use a second layer of polar ice, surprisingly you don't.

I have a clear plastic fork for you, how would you know what's going on? I love it, you can see where all the stress concentrations are and this is relatively like a gradual transition and then it gets crazy, right, yeah, engineers actually use a similar setup of polarizers to look for stress in samples of materials, it's called polarimeter, okay, so how is it possible to get these beautiful, crazy rainbow colors when all of these things are

light

or gray? Let's start talking about what these polarizers are, the lenses of your polarized lenses, those are polarizers, they are filters that allow light to pass with a certain orientation.

I am going to ask you very politely to please pretend that this string is a light wave except that light It is not a string that moves up and down, it is an electric field wave that goes up and down with a perpendicular magnetic field that also waves, so light waves can go up and down, but they can also go from side to side. and diagonally, and the direction in which the electric field waves is called the polarization of the light wave, so the rope is not light, please pretend that it is vertically polarized, horizontally polarized, diagonally polarized, light that reflects off puddles and oceans is often horizontally polarized, depends on the angle, depends on the flatness of the water, but note that I should probably mention that too before

some

one in the comments scolds me for not mentioning that there are also circularly polarized light and elliptically polarized light, but those come from adding different linearly polarized light waves, like this horizontal light and this vertical light that are out of phase and then there's unpolarized light, which is lighter and that's just a bunch of Random polarizations add up very well, now polarizing filters

only

let light of a certain polarization through, for example, if this is a vertically polarized filter, it will

only

let through the life that is vertically polarized and block the rest of the light, interestingly the light. that has a diagonal polarization, some of that will get through because it has a component in the vertical direction, so how much of that gets through depends on how vertical the diagonal angle is and now if you want to block light reflecting off the water, it should block horizontal polarization, so a vertically oriented rising post filter is used, that's what manufacturers do with polarized sunglasses: they orient their polarized lenses to block horizontally polarized light, so If you have polarized sunglasses, you can turn them from side to side to make sure they block light reflected from flat water surfaces.

Also, the light from LCD monitors is polarized because LCD screens have a polarizing filter in front of them, so the light from your laptop screen is probably polarized and although some animals can detect this polarization with their eyes, we,

humans

, we cannot do it without the help of sunglasses, or we, the biology of the human system, can actually perceive the polarization of light and you will too during this video, but first let's understand how and why some animals perceive the polarization of light. The natural world is full of flat surfaces that can linearly polarize light, such as wet leaves or bodies of water.

The scattering of light in the atmosphere or underwater can also partially polarize light and all this information is used by animals for various reasons. For example, the polarization is perpendicular to the direction of sunlight, so the Birds, insects and even some mammals use it to orient themselves when they cannot see the Sun directly. Cuttlefish that have this surprisingly subtle perception of polarization use it to hunt silvery fish even when light is reflected. Camouflage and other predators are even able to detect the most transparent animals thanks to polarized lights. This is because light becomes polarized as it passes through the animal's tissues and the poor prey becomes visible to the predator, so the polarization of light is an extra piece. of information that animals use in many different ways, but what about

humans

?

Well, let's try something first. Get this video in full screen and watch it. You can also do it with any blank image if you don't trust me. Now tilt your head from the left. to the right slowly while looking at your LCD screen, tell me if you see something filling your what size spaces, like there is a dot in the middle and then it looks like lions like diagonal lines. I don't see what color it is. color just yellow, oh okay, maybe it's right in the middle. I was looking through the mail. Yes, there is some yellowing.

I guess it's okay, like stains. It's whether your screen is cleaner than the physics girls. A very faint beige and blue pattern of size. of your thumb should appear if you don't see it or if you're not quite sure what you're looking for, the pattern should look like this, yes I noticed the soft yellow spot, this pattern is called idea brush and it is believed to be caused by the presence of yellow pigments arranged circularly in the retina, so there you have it, yes humans can see the polarization of light, some humans can see polarized light, that's so cool, biology gains some credibility today in the physical girls channel, okay, let's go back to The final little mystery of our demo why the crazy colors, so the key is the ribbon, whatever material the ribbon is made of, it actually spins or spins the polarization of the light as it passes through it, it spins it differently for different colors of light, so you get the polarized light passing through in turn and twisting and then hitting the second filter.

Only the light of certain colors has been bent by the right amount, bent at the right angle so that it can pass through the second polarizing filter and most of the rest of the colors. They are blocked, so you get first preference for some colors and not so much for others. Now, if you twist the second polarizing filter further, it's different colors that have been twisted the right amount to pass through and the result is great, thank you very much. Leo, who came and offered that super interesting information. You can see his channel. It's called dirty biology and I link to it in the description.

It's in French. FYI, also thanks to Allan Pan and William Osmond who helped with the channels for him. They are incredible. crazy, fun and projects I've linked to your channels in the description too thanks for watching and happy fixing I'm going to go take a nap. It's a joke. I would like to thank the brilliant organization for supporting PBS Digital Studios. The brilliant organization is a unique learning site that offers practice problems on all kinds of things. You can check out the symmetry lesson to learn about snowflakes and then challenge yourself with exercises for science enthusiasts like us.

Bright org offers interactive challenge problems and then you can learn the underlying concepts to check. come out bright or go bright about org slash physics girl. I'll put that link in the description and the first 200 to click will get 20% off a yearly premium subscription for a very varied variety in number three and that's right, something simple and readable, let's say competitors analyzing something simple madaba is a young man concussions the middle ball is