EDIT: As Orion has pointed below, this effect can indeed be explained through Quantum Mechanics. It just happens that EM wave theory can also explain this effect if we describe it using linear superposition of the polarization angles. However, while the EM version "makes sense" the ultimate complete explanation is quantum mechanical in nature. Thank you Orion for pointing this out.

That was really interesting. Thank you Orion. This is a perfect example of why KZfaq was conceived in the first place, for interesting, educational short films like this. Brilliant.

The paradox appears by confusing the function of a polarizer with that of a filter. Polarizers do not strictly filter (remove) components of the light, but can _add_ a polarized component to the light. If completely vertically polarized light hits the horizontal polarizer or vice versa, it is completely filtered. However, as it passes through the 45-degree filter, some of the light will be both horizontally and vertically polarized, making it survive the final filter. This perfectly explains why less light is filtered when the angled polarizer is placed in the middle, rather than the beginning or the end. You do not require quantum mechanics to explain this effect, so by Occam's Razor, it is the most likely explanation.

Thanks for the video. I have always been fascinated by this effect. I will go and look at the link.

It's more like telling the photons come through the first filter to polarize diagonally, which isn't enough for the third filter to block them. The other two filters combined with no interruption will always block all light. So that makes sense to me.

It's easy to understand if you think the lens are "turning / twisting" the waves to the arrow direction. So when you put the third filter diagonally between the 1st and 2nd filter, you are just 'undoing' part of the turning the 1st filter did.

I searched "three polarized filters" and this was the first result on Google. I was not disappointed.

This is a simple phenomenon and easily calculated with same math for doing vector decomposition/projection. Imagine you have an ice cube that is inside some rails that only allow it to slide from left to right, and another one in another rail that only allows it to slide back and forth (i.e. perpendicular to the first rail). If you throw one against the other, the other will not move, because the impact force is perpendicular to the direction it is able to move. But if you have a third cube in a diagonal rail, you can push the first one against the diagonal which will then slide with ~0.7 of the speed of the first one, and that one can hit the third one which in turn will slide with 0.5 of the original speed, thus able to "rotate" a force by 90º (but losing some of the power), where before it seemed impossible. This will not work if that diagonal one is the first or the third, same as we see in the video.

An intuitive thought to make it less disturbing: A pipe you send balls down, theyd get stuck on a 90 degree turn (assumed). If you add a 45 degree on that turn (so 2 45 degree) then their path is easily directed around the corner. If you place 45 degrees before or after in such a way as the 90 degrees is unaffcted they halt. So it doesnt seem that counter intuitive, although they are not pipes and this does not explain the mechanics at work....disturbing? Doesnt seem so, not like a delayed choice quantum eraser or anything, what would be disturbing is if the order didnt matter!

Really deep and interesting stuff! Do you have a link for the filters you use? (Just find some filters without the practical plastic frame)

The experiment of polarization is best done using microwave, since you can see the physical structure of the polarizer. In case of three polarizers, we can demonstrate that the light coming out from the diagonal polarizer has diagonal polarization state. By turning the third polarizer in line with the second polarizer, you'll get brighter light compared to when it's vertical or horizontal. I've made many videos investigating behavior of microwave transceiver here in KZfaq. I conclude that objects interact with electromagnetic wave following the same rules as how radio antennae work.

Let us assume, for the sake of argument, that, instead of polaroid filters, we are using black filters with a hole in the center, We have to put our eye close against the hole to be able to see directly beyond it. Rotating the first filter misaligns the hole relative to the hole of the second filter, showing us, besides the scene directly behind the first filter, the black and opaque surface of the second filter. If we now put a third filter between the first and the second, at 45 degrees, still with our eye against the first hole, we are able to look through the hole of the third filter, at least partially, all the way through the second filter and beyond.

Where can I purchase these filters please?

Was there a reason that you could not put the camera on the same level as the filters?

Hello, how much do you estimate the visibility rate when you put the 3 polarizers?

Thank you so much

Tapered cork screw effect of q wave?

My mind says it’s just bending the light between the horizontal and vertical to be in between, diagonal, but once you block the light with sequential filters the light has been stopped already.

The 'Three Polarizing Filters' experiment is the BEST demo of quantum physics. I would enjoy hearing anyone explain how this works; where the hoi polloi (me) could understand. The first principle is that you must not fool yourself and you are the easiest person to fool. - R. Feynman

The "quantum" part is not to see light as only photons. QED has taught us that they are both wave and particle, or neither. Quantum field theory, Feynman, ..... Best way to think about it is in a probabilistic wave approach, rather than a deterministic. Which then explains the "why" behind the questions asked. Their probability (i.e. the probability of light/photons passing through) concurs with light intensity passing through as shown in these experiments.

Could this be used to make a secure device screen that will appear black to onlookers but dimly lit to someone sitting still wearing glasses polarised to the correct angle?

It’s not creepy to me, i find it magical and awesome!

I thought you can explain this phenomenon by the wave nature of light.

What happens if you shine a high powered laser through it? Does it diminished to nothing too?

i think there is a common sense answer that denies the unique 'strangeness' of the QM explanation. If we replace 'filter' with 'how easy is it to twist' then instead of What percentage of light is 'filtered' by a polariser at angle x, we ask 'what percentage of light is twisted by a polariser at angle x'. To twist light 90 degrees is not possible with one polariser, because it is impossible to twist light 90 degrees with one polariser. But it is possible to twist light 90 degrees with 2 polarisers, because any angle less than 90 degrees is possible to twist with one polariser. So long as our 2 polarisers have a combined twisting of 90 degrees, but each is less than 90 degrees .... then no surprise. Its like saying "If i cant twist a screwdriver 180 degrees with one twist, then i can break it down to 2 twists". The most efficient would be a half way to the desired twist angle for both twists... ie 90 degrees for the hand held screw driver. So similarly .....for polarisers that are not capable of twisting light 90 degrees in one go .... then use 2 polarisers instead .... with each twisted at 45 degrees, to be the most efficient light twisting of 90 degrees using 2 polarisers. (2 equally difficult twists) looked at this way there is no mystery at all. We use screwdrivers all the time and and we dont grab hold of the handle and run around in circles. We break it down into multiple twists. But the reason we are tricked into thinking the polariser filter paradox is strange is because we think of filtering ... not twisting. If they were called 'polarising twisters' we wouldnt be surprised by the effect at all.

use polarized filters that reflects 50% of the light on one side, it may not get the same affect, I think polarized filters breakdown the field, the filter in between merges the field.

Couldn't it be because of the polarized glass? because it goes inbetween set 1 and set 2, at a diagonal angle you open the flood gates again essentially? And its not a quantum effect. It be crazy if it came after the final one. Or if you kept doing this in a chain with hundreds... that would give us an answer. what happens with 6? and two at a diagonal? what if you did opposite diagonals?

quantum efect; 1) first filter vertical: only vertical polarized photons pass 2) filter diagonal: 50% of diagonal polarization pass 3) filter horizontal: 50% of horizontal polarization pass from diagonal polarized photons.

I don't think that's a quantum effect. Doesn't it have to do with the direction the waves are passing through? So you change the angle by changing the location of any particular filter.

Nice name! I love physics too, what a coincidence

I think it's due to directional waves...the small change of degree the transferability of photon will get through...Whereas the large sudden change will put to halt.

different lighting set-ups and use a laser pointer...

Insane!

Isn't it possible or likely that each polarizer is polarizing the light with itself? For instance, 50% of the light makes it through A. B is 45 degrees to A, and each photon has a 50% chance to be polarized now to a 45 degree angle. C then is 45 degrees to the incoming light, and we reapply the 50% chance to repolarize. In the end, we should end up with 12.5% of the incoming photons, all of them polarized in the same direction

Seen this plenty and lots of people reckon they can explain it. But no explanations that I have seen make sense. It actually defies all theories of light, including QM and wave-theory.

this isnt a quantum effect. Iits just a normal vector component effect. you can get the same dffect with forces (which are also vectors). if you pull something up it wont move sideways. if you pull sideways is wont move up. but if you restrict the movemend in 45 degrees you get a movement sideways when pull up.

is this a malus’s law?

I have discovered a truly marvelous explanation for this, which this comment field is unfortunately too narrow to contain.

Thumbnail literally felt like the video was a render

God I love this. I have actually won a bet with this effect.

The diagonal filter can't unblock sunlight that never gets to it.

I'd be more creeped out if the effect was happening when holding the filter between the camera and the two standing filters.

So apparently to solve this we got to assume we live in a simulation and there is a background system that is rendering out world. Much like a game being rendered by a computer in real life.

Search on KZfaq: Polarization of photonic light journal.

Hmm, I think photon is the paid actor!

I so sorry it hard for me understand but I want to understand this :(

i have a idea that ur massaging the waves into a spin

Ever try wearing polarized sunglasses beneath a motorcycle helmet with a polarized visor? It's pretty weird, especially when you turn your head.

dopeeee

Make it 6 time to see what happens. If you have enough filter maybe you can get down to only.one photon.

So a gradual change in angle from filter to filter (instead of a sharp 90° difference) allows light to pass through. While a stark difference in angle blocks it. Kind of like a flow of water, if gravity wasn't that much of an influence.

its not complicated if you just think about it.

Get something to do

We can also do this with two sunglasses too?

No, you're not asking the same question each time. In 3 of the arrangements, you're asking "Can I see horizontally-filtered light through the vertical filter?" By putting the diagonal filter in between, you're changing the horizontal light to diagonal light. Then the question becomes, "Can I see diagonal light through the vertical filter?"

I woke up this morning thinking about this experiment and using it on entangled photons. It is always said that you can’t use entanglement to communicate faster than light because you cannot “know” the polarisation of a photon until you measure it, and then it is destroyed and so if you measure its entangled twin, it won’t allow you to infer any information about the other photon. But it seems here, that you can actually change the polarisation of a single photon by using several polarising filters. Surely, this method will allow you to encode information in the polarisation, and hence in the polarisation of the entangled twin, and so “communicate” (I know it’s only a kind of synchronicity) faster than light.

Here is explanation for casual brainer. Basically everything around you (energy, matter, etc) only "rendered" when they are "interacting". If not, they are just "wave function". A chair is only a chair when you sit on it. Now what happen in this video. The light that travel throught filter needs to interact and choose how to proceed. So 2 polar lens that is opposite in polar cancel each other. Making the object looks black. Now by having 3 polar lens at an angle. The middle lens is basically tell the light to choose pass or not, making the light "change" polar properties. Therefore, 3 filter have more light than 2 filter, because the middle filter force the light to interact and "choose" (Aka become particle) at an angle. This is the weird thing about quantum theory. We might as well call our world simulation at this point

The so-called paradox is also easily demystified simply by changing the order of the polarizers. In order of appearance A horizontal B at 45 degrees of A C vertical The end result will be exactly the same as with the "paradoxical" setting whereby C is slipped in between A and B, but without first turning A dark and opaque. Somebody not present while the polarizers were being set up would never notice the difference, since there is none.

I love when people pretentiously confuse description with explanation

Makes me think of matrix multiplication

We all searched for this… didn’t we?

Interesting topic but incomprehensible speaking !

Glitch in the Matrix

Why this always confuses Simple-Minded people Is because some commenters think light is a particle and some commentors think light is a wave. well, it's neither, Light is a coaxial perturbation of the aether. It is neither a particle nor a wave. Light does not travel. It propagates, there is nothing moving from here to there. Nikolai Tesla said "Light propagates through the aether the same way sound propagates through air." The speed of the action is dependent on the medium that it's propagating through. Light propagates at 186,284 mps. That is the rate of induction of the aether. Sound propagates roughly 1100 feet per second in air, at sea level. Through water, sound propagates many times faster, through steel, sound propagates at 85,000 ft per second. So you see, it's all dependent on the medium. Light and sound are nothing more than compression rarafaction events of a medium, Frequency specific. You're welcome... .

👏👏

I don’t comprehend the logic of your demonstration, as to why you are disturbed. As what a comment mentioned, the sequence of polarisers is the key fundamental issue. Explaining in layman terms, a polariser only lets light pass through along its axis of polarisation. Basically if two polarisers are crossed, i.e. their axes of polarisation is 90 degrees or perpendicular to one another, no light will not be able to be transmitted beyond the second polariser since cos90 =0 (you can apply Malus law for polarised light where I =Iocos^2θ). So if you take a third polariser at axis 45degrees and put it in front of the two crossed polarisers, no light will be transmitted beyond the last polariser since the issue here is that there are still two consecutive polarisers in crossed alignment. Even if light were to be polarised by 45 degree, the two consecutive polarisers will eventually result in cos90 =0. Same effect if you placed the 45 degree polariser as the final polariser - no light is transmitted since the first and second polarisers are still crossed so there is already no light to be polarised by the time it reaches your 45 degree polariser. So the only way to let light through is to put the 45 degree polariser IN BETWEEN the two crossed polarisers so that a component of light can be transmitted (Icos45 in this case). This is a typical physics problem involving three polarisers. Look it up on KZfaq.

If your are a positive person you will get a positive answer. If you are a negative person you will get a negative answer. If you are unsure you will never be sure of your answer. The power is in the question not the answer.

it bounces off the diagnoal lines at an angle that allows it to penetrate the vertical polarization...if this is real

Portal 3 confirmed...

QuAnTuM EffeCt

Imagine looking through a periscope but all you see is darkness. Then you realise one of the mirrors is missing. You slide in the missing mirror and now light is able to pass through the periscope. That's similar to what's happening here, just easier to comprehend. Nothing is spooky or magic when you understand how it works.

having my own personal views on how light propagates, i cannot accept a transverse wave as even being possible... i only ever see transverse waves on the SURFACE of things. at the junction of two media, where one is free to oscillate in the other... and in doing so, will produce perpendicular compression waves in the OTHER medium. i have never seen any example of a transverse wave propagating THROUGH anything. it has been demonstrated with ultrasonic arrays that sound can be "beamed", much like a laser... you cant detect it at right angles, its passage. only its interference with something... "theres the red dot" versus "theres the sound"... a lightbulb sprays light everywhere, as does a loudspeaker... we can manipulate both with reflectors, parabolas... to me, this relates back to sound, and the fact that when we "see", we are using an array of tiny sensors that are still LARGER than the wavelength they detect, and further apart... whereas when we HEAR, we use a SINGLE (pair...) membrane that is far SMALLER than the lowest wavelength it detects... but also, just as importantly... the way the... "impulse" is created in the first place! why do i see colours with plastic, a change of FREQUENCY, but plain polarising filters are always just... filters? they filter ALL wavelengths, not selective ones... the "rule" that one cannot "polarise a longitudional wave" aka compression wave was "determined" before we had amplifiers, microphones, speakers, radio... i havent seen anyone challenge that theory... and thats what it is.. a THEORY.

This is just the consequence of Malus' law, there is no quantum effect involved.

Kant noumena

Polarization is a wave phenomenon. There is nothing quantum about this demonstration. When the 3rd filter is placed between vertical and horizontal filters it repolarizes the light from the vertical filter and transmits a component of that light (the cosine) to the horizontal filter. That 45 degree polarized light is then repolarized by the horizontal filter and transmits a component of that light. There is only 100% blockage when the light passes directly between two filters that are at 90 degrees. (like when the 3rd filter is first or last in order. Any other combination allows some light to transmit. Photons don’t “know” or “hear” anything. Anthropomorphizing photons is not helpful and leads to discussions of “consciousness”.

Sorcery.

All it does is finish the rotation.

This is a result of polarising filters not being “perfect.” Nothing more.

Light is an electromagnetic wave. Same as all other RF, and behaves the same way, but has much smaller wave scale. This is simple constructive/destructive interference. There's no magical woo woo taking place here. Same thing happens when you use a yagi antenna at lower wavelengths, and put it in your living room. Only difference is, your eyes/brain don't assign colors to it as it interacts with matter. So you cannot "see" it, but you can use a radio transceiver to "view" the exact same effect. Radio tower transmits signal. Signal strikes various objects as it propagates towards your house, and then it passes through the walls of your house, causing destructive attenuation of the signal. Then, when that now weakened signal strikes the yagi antenna inside your home, it can be constructively interfered with itself to increase the signal. If the radio signal was transmitted only vertically polarized, and you turn that yagi horizontal, you'll lose half the power roughly. Turn it vertical, and magically the signal gets strong again. Most radio stations transmit their signals both vertically and horizontally to account for this, and this is how light is too (circularly/vertically/horizontally polarized depending on source). Quantum nothing. It's just how electromagnetic waves work. There's no magical BBs of light being stopped by those filters, or passing through them. It's an induced wave. It's components are already on all sides of those filters, and moving omnidirectional.

Yeah no shit.

I understand nothing.

Not everything is associative man. We have seen a lot of examples in mathematics. Why it seems weird to you. This is simply not associative. Rather it is commutative. Each polariser act as an independent source which is followed by Huygens' principle.

I think that happens because light enters from the sides also. If these lenses were in a tube there would be no extra light to influence your answers.

This intuitively makes sense, think of it like a percentage of light being filtered; percentage wise the first polarizer removes 50% of light, the second polarizer at 90 degrees from the first removed the other 50% reaching 0% light throughput. Adding a third in between at 45 degrees removed only half from the first 50%, giving 25%, then the third acts as the first polarizer resetting the wave direction, passing fully through the last one.

Nothing quantum is here. And nothing creepy or weird. Can be easily explained with classical theory of light or electromagnetism. Can be easily explained in the normal framework of QM without any weird stuff or creepy stuff. Not a quantum effect at all, at least not more quantum effect than me swimming in the sea.

Could the explanation and think about Einstein's words "I like to think the moon is there even when I am looking at it" means that there is some kind of universal conscientiousness is always looking. Know what I mean? That God is spooky?

It is not creepy ... that JUST how it works!

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The difference between the two explanations in the description is hilarious. Quantum physics is a joke I swear to god. I mean obviously there is a lot of real and good science in quantum physics but there is so much gobbledygook in how it is conceptualized and talked about.

😂🤣😂🤣

That's because the middle polarizer has shifted the angle. There is nothing odd or strange about this. What you just did is deterministic and not random. You are getting the same results every time. You need random answers for this to become a quantum effect. Because quantum mechanics is essentially obsessively using probability and statistics to small scales where both position and time of atoms cannot be known simultaneously.

sus

Stopit

Lets have another example. Pass a light from a circular hole of radius 5cm and then another hole in the sequence having radius 0.5mm. Now reverse the order. Did you see the same result, the same intensity of light?. ofcourse not. Sequence matter here. What is weird here? Nothing. Use another punch hole of radius 2cm. Keep shuffling them. See yourself. Will not get same result in every case. Asking questions in defferent sequence are not same, sequence actually matters.

So you can't explain it either! 😂

Interesting visual but terrible explanation. There are much better out there...

It frustrates me so much that people call these things "creepy" or "weird". No, it's creepy or weird just because you don't understand what's happening and want to attribute everything to "magical quantum mechanics". That's not a scapegoat for being uneducated. This isn't a "quantum effect", it has nothing to do with "asking questions" or "getting answers". You aren't "asking photons questions". What a moronic thing to say. Educate yourself.