Polarisation - Sixty Symbols

[@Aragornaz]

Demonstration with radio waves and sheet of metal bars makes polarization much more understandable. Wish more people would explain it like this. Thanks!

[@uploadJ]

But, the presenter still errs in the final analysis of why/how this phenom works. I thought for a bit he was going to get it - but he swung and missed! As it turns out, the metal grate is re-radiating the microwave energy in the direction that the grate is positioned, having intercepted the RF from the transmitting end at 45 degrees, then, re-radiation of the RF takes place at the new 45 deg angle AND is picked up at the far end receiver.

[@neonsashimidream1075]

@@uploadJ This is definitely the Occam's Razor explanation. I felt the same way when I first stumbled upon the Quantum Physics explanations of this phenomenon. It seemed like they were going way out of their way to create an impossible to answer question. I would love to find an experiment that either presents evidence for or against the solution you just described. If the obvious explanation is the correct one, why do all of these physicists seem to miss it?

[@FuburLuck]

@@neonsashimidream1075 If that's your thought, why do you think it would be re-emmitted in the same direction as the original signal, rather than a random direction? Why would light continue in the same direction from the filter, rather than emitting fainter light in all directions?

[@uploadJ]

@@FuburLuck re: "why do you think it would be re-emmitted in the same direction as the original signal" It does not re-emit at the angle of the orig signal. It re-emits at the *angle* the grate is *now*. Each wire radiates at the NEW angle on to the destination.

[@-danR]

@@uploadJ . I can't tell whether he missed it or that the presenter's explanatory style is so bad that it amounts to the same. What is depressing are the comments--the inevitable YT comments--praising the explanation with: "Wow, great explanation." "More than I learned in a year of high-school." "I wish my prof had put it this way." "Now I _finally_ get it!" No, you don't get it. Or else you're a genius at extracting the truth from a malformed explanation.

[@Niscate]

Badass final sentence. Someone should put sunglasses on him in the last frame.

[@MajorMandyKitten]

#DealWithIt

[@texasdeeslinglead2401]

This one of the demonstrations that blew my mind in high school. Lead me into the wonderful science field of plumbertology

[@suivzmoi]

you know what's interesting about that wire frame? put two together perpedendicular so you get a wire mesh that effectively block all possible polarisations of EM waves with wavelengths larger than the grid size. it's called a faraday cage and it's the same concept used on glass doors for microwave ovens...

[@ZomB1986]

Brady, show us more about polarization. In particular circular polarization, the difference between electric and magnetic parts, and how these parts are each a complex number.

[@sixtysymbols]

@DungorCee: Sorry about that... today is my last day on the project (for a short time, I hope) so getting everything finished. All done now!

[@JacobthePoshPotato]

Wow! I am impressed by how informative this is. Thank you.

[@whade62000]

"...which I'm going to enjoy" xD Roger Bowley is my favorite! (and with the other utterly amazing professors on this program, I mean that as a big/personal praise.)

[@phynos8936]

This came up in class last week. Especially the bit about slipping a polaroid sheet at 45* in between two sheets that are offset 90*. I thought the wave could be thought of as components but I wasn't sure. Now watching this I remember where that thought came from, I watched this video a long time ago. Excellent.

[@obiwanjacobi]

Look at you digital watch with your Polaroid sunglasses and then turn the watch 90 deg. Same thing.The LCD display of the watch also has a polarized film on it.

[@holsson85]

We used microscope with polarized lenses while studeing thin sections of rocks. The different rocks consists of different minerals or verious rations of minerals. Each have their own "look" in polarized light meaning that they could be identified, even if they appeard only white,gray or black to the naked eye.

[@12gabriel3]

sblackNY actually, you can't convert something into electric tension without also making current, as they are corelated. And no, not all radios need a power source. There is a "famous" model that they used to do in WWII or WWI (can't remember) that uses a crystal earphone. Just google for "crystal radio" and you will see. It's very intresting easy to build! Weel, at least as long as you can get hold of a crystal earpiece.

[@NirrumTheMad]

"now Brady, this is the bit that really is going to do your head in. Which I'm going to enjoy"

[@Pedozzi]

this is mindblowing, id need a way more deeper lesson on this topic

[@veso5863]

SASSY

[@RMoribayashi]

I've had to give up my Polaroid sunglasses because of LCD displays, which also use polarized light. The angle never lines up correctly with my sunglasses and I end up seeing a black display.

[@GarretKrampe]

What interests me is that when you changed polarity the detector had a peak higher than the steady state. One explanation could be an AGC (auto Gain Control) in the detector. Can you verify this point for me please. Garret

[@siggyincr7447]

I was curious about that too. Especially since he says that it's all about probabilities of the individual microwave photons getting through, he says 25% likelihood. Then why is the signal not 25% of the aligned signal? I wonder if the polarizer isn't converting the polarity instead of filtering it, and possibly focusing the beam.

[@AndyPayne42]

Siegfried Gust Why would it be filtering if he's getting the same steady state signal (~4ma) with the receiver/transmitter and aligned?

[@parthpandya7077]

I was also amazed by the same the grid of polarization acts as a focusing channel and not as a diffusive channel it does not obeys the law of conservation of energy Either there could be a fault in the receiving side

[@abramthiessen8749]

Or he could have increased the power of the emitter between cuts.

[@LAnonHubbard]

They did the first part of filming in the morning and the second part in the afternoon. In-between they used the microwave apparatus to cook their lunch on max power.

[@Sporkabyte]

So an electromagnetic wave can be split into its component vectors? Hopefully I've interpreted his analogy with the square correctly

[@ExCoSeH]

Yeah that's how I interpreted it as well.

[@stensoft]

They are actually not component vectors of the original wave. You would have 25 % signal even without the filter if they were. But when you measure the wave (with the filter), it is forced to turn either parallel or perpendicular because it cannot interact with the filter in any other orientation. It's basically magic.

[@davecrupel2817]

You may know a magicians secrets. But his tricks can still be impressive. So it is with physics. those polarization tricks on the overhead are wicked awesome even despite knowing exactly whats going on.

[@Moondye7]

either me !

[@harleyspeedthrust4013]

Wat?

[@peti6c]

Best comment section I've seen in a long time. Btw, Sixty Symbols is awesome!!

[@hamdaniyusuf_dani]

3:10 When the orientation of the conductor in the filter is in line with the transmitter, the wave will be mostly reflected, rather than being absorbed by the conductor.

[@RMoribayashi]

Here's a fun thing to do if you have two pieces of polarizing material. Align them so almost no light gets through. Place a clear CD case in between them. As you rotate the case you can see a moving rainbow of colors, especially at points of stress. I first saw this effect when entering an office building that had doors made out of some kind of tinted safety glass. I was surprised to see a wavy stripe of bright colors across the middle of the door that disappeared when I took off my sunglasses.

[@gregcampbell3493]

Thanks for putting this together. Fascinating stuff.

[@tiagotiagot]

I think some satellites do it like that to send about twice the amount of data in the same frequency range. Also, that is how passive polarized 3d (actually, just stereo) projectors work, two rolls of film, two lenses each polarized 90 degrees to the other, and the people watching the movie wear glasses with the lenses also polarized 90 degrees from each other (there are also some that use circular polarization, the lenses are polarized the opposite of each other)

[@douro20]

It is said that the guy who invented polarizing film was expelled from the college where he was studying chemistry...and for about 3-4 years he sneaked in to the lab during the night to work on it.

[@forglegorktheork]

But don't stop making videos! We all hope to see at least another sixty symbols!

[@whatitmeans]

I think phisics made a mistake in its classic explanation: when the signal reach the metallic grid, in the spaces among the bars we could considera individual sources oscillating based on Hyugens' Principle, but their spherical wave will be distorted since the electric field will be stopped by the metallic bars in its perpendicular direction, making in this way a boundary condition for these point sources, leaving sources that can only oscillate on the parallel direction to the bars which explain why you got power in this direction... like in scattering processes you cannot just said that only absorption has ocurred, you should consider the participation of the electric field from all the molecules in the path of transmission

[@xtieburn]

The photon is in both states but must be recorded in one, which one is based upon a probability. So its still not deterministic. Consider a perfect dice, it can roll 1 to 6. That doesnt make the roll any more determined even though you have a mathematical framework for assigning probabilities. It will ultimately have a 1 in 6 chance of landing on any of those values and that renders it non-deterministic. Its the same with the state of the photon and how it is ultimately observed.

[@vinigretzky97]

I can't stop watching these videos.

[@RMoribayashi]

I don't think so because sound is a longitudinal wave. The waves have the same direction of vibration as their direction of travel. Light and other electromagnetic radiation are transverse waves. Their waves are at right angles to their direction.

[@texasdeeslinglead2401]

One of my favorite speakers on bradys channels

[@Forssa1]

It be really cool if you showed an experiment how to combine two separate laser beams into one, or spit one beam into two with a polarised cube.

[@Coldstaceyiscold]

I love sixtysymbols its my favorite channel now

[@hankh825]

This experiment also works for magnetic field. Microwave in the video is a transverse electromagnetic wave, which is composed of e-field and b-field orthogonal to each other. Only detector should be magnetic field detector.

[@valtih1978]

They explain that vertical wires serve as the secondary transmitter: the waves induce since oscillations of electrons in the wire effectively absorbing the wave. Ok, let's believe that wave is absorbed when it forces the electrons. But, the other theory says that reflections work because secondary source produces the wave. Yes, oscillating electors must emit the waves in the same direction as the inducing wave. So, probably, we should speak about scattering rather than absorption?

[@sblackNY]

The antenna collects the signal, and computer chip deciphers the signal into audio, but needs an additional power source to amplify the signal sent to the speakers.

[@sblackNY]

We can, it's called a solar panel...radio waves are not converted into current, all radios need a power source (batteries, outlet, etc)

[@GRAHAMAUS]

@Dirtboy101 Because this apparatus is only a few milliwatts, not hundreds of watts like an oven. Why does a tiny light bulb not harm you when a big one burns your skin when you touch it?

[@hamdaniyusuf_dani]

after passing the 45 degree filter, the microwave's orientation is actually rotated by 45 degree. that's why when the receiver is at 90 degree to the transmitter it still gets signal. no magic is involved.

[@DW-iq8lt]

Thank you. Could you also talk about how molecules (or dielectrics) interact with EM waves to produce Brewster's law?

[@DsNHira]

Greatly explained about road and river reflation and polar glass activity which I was not aware of. I knew about polar glasses and how it works though but your explanation was awesome and made my brain clear like looking inside pond wearing polar glasses. Thank you.

[@xtieburn]

I should be more wary about using analogies. QM taken to its conclusion shows that even if you could see right down to planck length you still wouldnt be able to determine every detail. Particles are fundamentally not deterministic. When you refer to knowing the force of the throw etc, its a round about way of referring to the hidden variable theories that have been largely disproven. The more we see, the more it becomes apparent that Classical mechanics simply dont work with the quantum world

[@Infernoraptor]

What's radial polarization? (the kind that mantis shrimp can see)

[@junkbucket50]

Q. What happens if light passes through a white mint? A. It gets polo-ised

[@uploadJ]

NO probabilities are required here. Simple trig and RF (radio frequency) principles are ALL that are necessary to explain this.

[@sterby1]

You need probabilities and QM to explain WHY it works and why it can be explained by the aforementioned trigonometry and RF principles. Knowing that you have something big and fuzzy in the background makes a huge difference in this field.

[@buergi]

I don't quite get why the microwave cannot pass through the grill horizontally. Shouldn't there be certain distances where the wave just "slips" through the grid?

[@dormirenonpotest]

+Christian Bürgi microwaves can get to have wavelengths of up to 100 cm, so as long as the bars are closer together than the wavelength of your emitter, the waves which aren't polarized the right way will be stopped.

[@osere6432]

Don't think about it as a thing that moves forward in a sine wave shape, think of it more as a spring that stretches and shortens perpendicular to the direction of travel

[@themomaw]

Soooo.... is it possible to have a system where waves are traveling together so their peaks and valleys are exactly lined up, but oscillating in different planes?

[@thunderbolt997]

i think i know how polorize filters work in cameras thanks :D

[@kabalder]

:D "oh, I'm just really fascinated that this actually worked". Basically how philosophy-lecturing works as well - you hope, beyond hopefulness, that when you teach someone they will manage to use the tools and the theory. And follow the reasoning, to the point of actually understanding it, and making the terms their own. And then manage to use these terms and meaningfully argue towards conclusions without help, in a different context. It's still the same principles, and it should hold true, it has before, etc. So you expect it to work. But it's still almost like magic every time it actually succeeds anyway.

[@Envergure]

That microwave thing is awesome. I have kept two polaroid filters in my wallet for the last year because they're so awesome.

[@JungleBeats69]

Great video! Where can we buy the polarized film you're using?

[@Atrix256]

"we have to talk about probabilities ... it is not deterministic" Would it be more accurate to say that they aren't probabilities as much as the photon is in both states with a value of 0.5 for each, and thus it still is deterministic?

[@cyberlightbeing]

How about extending this topic further to cover circular polarisation.

[@GRAHAMAUS]

@jackerd12 It's only a few milliwatts, not hundreds of watts as in a microwave oven.

[@firstnamelastname4752]

I imagine the antenna just collects the EM (radio)wave, then a transformer makes it into a current for the speakers. I don't actually know, but that's what makes sense.

[@hectorbector11]

Exactly, although I should point out that according to quantum physics even Protons and Electrons are just more complex waves.

[@markorakic1]

Why your filter look like a chain of spheres when not filtering?Look like oscillating on wavelength of a radius of that small sphere.

[@Edge0fPain]

I'm assuming he didn't talk about the maths judging by the comments so here you are: I (incident) = I (maximum) x (Cos of theta) Implying that at theta = 0 degrees cos theta = 1 so the Polaroid doesn't block out any light. But at theta = 90 degrees (perpendicular) cos of 90 = 0 so I (maximum) x 0 = 0 so there is no incident intensity so all the light is blocked out.

[@Al-cynic]

OK, thanks prof, been trying to understand why you guys say vectors literally have two components that are really in operation at the same time.

[@Thrax005]

This is a very cool video, I really learned what polarization really is, and the professor is totally cool, I couldn't agree more.

[@dragos7puri]

Is there a way to see the whole uncut video (or videos, not only for this one, but the whole sixtysymbols videos)? Thanks

[@kolrabi]

I use polarizing filters for my camera to remove unwanted reflections. The type of filters I use have on the camera side a layer that makes the light circular polarized, which doesn't confuse the built-in light meter as much as linearly polarized light... :) Wait, what? Can you explain to us, what circular polarization is and how that layer on my filter manages to convert those two kinds of polarization?

[@IhorMe]

6:53 - you meant now it's coming out with an angle 90 degrees to what you're showing, right? =)

[@kaktotak8267]

One thing I don't like about this "component" explanation is that it implies that 1/4 of vertically polarized wave is horizontally polarized, which doesn't make sense. Also, why is the signal strength of that 1/4 is the same as of full signal? And why is the light that went through 3 layers at 45% angles is pretty much as bright as the light that went through 2 aligned layers, when only 1/4 of the energy should go though? It looks more like a polaroid film actually turns the wave when it's at 45% angle rather than absorb part of it.

[@qwerty687687]

I think the experiment isn't really calibrated to give exact results. I wouldn't rely on the signal strength as an indicator for the amount of absorbed radiation. As for the polaroid and the projector, one layer of ploaroid already reduces the brightness by 50%, so with three layers it should only be half as bright compared to one layer and I doubt the humen eye is sensitive enough to exactly determine the brightness, especially without a direct reference.

[@makingitsnowy]

This is the only one of there video's that has literally made my brain hurt.

[@thekaiser4333]

Witchcraft!

[@azeer1988]

+The Kaiser i was watching this and i was like: SORCERY!!! lets scroll down and see if i'm the only one who thinks that ;)

[@uploadJ]

There is no need for QM or choices or magic though ... this is just pure classical physics involving radio frequency energy (or light energy) being re-radiated by a structure set at 45 degrees from BOTH horns (in the second demo.)

[@Bsasma]

you can test this by using your ipad (or any similar screen) while wearing polarized sunglasses.

[@hondatb08]

Is this dangerous?

[@starkshift]

Prof Bowley! That microwave horn is most certainly not producing one photon at a time. What's being emitted is a classical "coherent state" of light, a coherent superposition of multiple photon occupation numbers, and the polarization effects you observe can be explained by Maxwell's equations. The quantum picture of things is valid, but largely unnecessary for your demonstration. :)

[@ThomasHaberkorn]

What is the number of polarisation states inside a blackbody cavity?

[@maplesyrup2944]

2:30 onwards. I had always thought that the conducting bars had to be parallel to the wave, so that the wave could get through. That's how all the physics book diagrams work, some show a rope and a fence, and the wave in the rope only passes if it's parallel to the fence bars. Clearly they seem to be wrong, because this man just explained it in more detail than the simple fence-rope intuitively nice diagrams. Thanks.

[@valtih1978]

+Maple Syrup I think that he is still wrong. He told that wave is absorbed and energy is converted into the heat of the fence. However, oscillating electrons must re-emit the wave at the incending frequency. The wave must be "scattered" rather than absorbed, therefore, IMO. The fence emits it in all directions instead of focused into one direction. It is like clouds scatter the sun light rather than absorb it completely, like black cover would. The question is why does polarizer prefers to absorb rather than reflect or scatter the light at the current wavelength?

[@valtih1978]

Open Feinman lectures and start reading. You do not need PhD degree in physics to understand a bit of common sense as you do not need any to say that induced current = heat.

[@maplesyrup2944]

+Valentin Tihomirov I have watched a lot of Feynman. And it's not common sense. You have even translated his videos, nice :)

[@rThorWenzel]

+Valentin Tihomirov The wave is in fact absorbed as it induces a current on the metal pole, which by ohmic conduction generates heat. The polarization of the poles turns them into dipoles, which in turn radiate waves in every direction. If the frequency was high enough, this would be the main source of heat dissipation, but it's shadowed next to conduction at the microwave range. It's called dielectric heating. Why the metal absorbs most of the energy rather than refracting or reflecting is due to the conductive properties of metal, the frequency of the waves, the geometry (parallel bars) and the position of the grid. It's like any other optical surface which transmits and reflects in only one direction. You can reflect the wave by angling the metallic polariser or refract it with some paraffin prism.

[@uploadJ]

@@rThorWenzel re: "Why the metal absorbs most of the energy rather than refracting or reflecting is due to the conductive properties of metal," Wrong wrong - completely WRONG. JUST because you "say it" does NOT make it true. RE-RADIATION from the wires occurs!!! This was EASILY shown BUT the presenter does NOT know it!

[@Fuglebolle]

If you're interested in learning more about the polarization of reflected light I suggest the Wikipedia article on Brewster's angle.

[@ishanr8697]

Fantastic, thanks for making!

[@Desmaad]

Would you guys mind updating this to include circular polarization? Thx.

[@jeff77789]

hey guys if you take the lenses off of the 3D glasses at the movie theatre then you can actually get the same effect as the very first demonstration

[@ayushsinha1813]

Newtonian Physics ------>> Electromagnetism -------->> Waves --------->> Quantum Mechanics is like going from text to images to videos to AR.

[@johnclavis]

I think you're cool.

[@weasaldude]

but i thought EM waves are in 3 dimensions and oscillate vertically and horizontally

[@kiril347]

can we do a polarization of sound waves? and if so, how does it work?

[@chris41188]

am I right in thinking this is similar to the double split experiment? as the photon is taking two states (the 2 diagonal stated) at the same time?

[@sortsvane]

Beautiful explanation. Loved it.

[@uploadJ]

Well ... it appears this guy gets it wrong too. He does NOT understand the metal grate is re-radiating the microwave energy in the direction that the grate is positioned, having intercepted the RF from the transmitting end at 45 degrees. So, re-radiation of the RF then takes place at the new 45 deg angle AND is picked up at the far end receiver. Physics REALLY IS screwed up.

[@carterhertner3787]

I think there is a mistake when explaining the effect of holding a polarize at a 45 degree angle. I believe the wave is changed into a circular pattern.

[@hjembrentkent6181]

No Santa created the universe

[@uploadJ]

You're close - the signal - RF or light - is re-radiated AT the 45 deg angle ... IOW - presenter "gets it wrong".

[@MsLilichi]

you may not wear sunglasses, but I think you're really cool for talking about such interesting stuff! :D

[@tiagotiagot]

Wait, i thought the EM oscillations happened on abstract axes (the Eletric and the Magnetic axes)... Are the oscillations really happening on regular spatial axes? 0.0

[@LutzDerLurch]

That guy is smart and cool, AND he wears by far the coolest Shirts!

[@MitkoGorgiev]

When the two sheets of Polaroid are vertical polarized, then the light goes through. In the second part, when everything is vertical polarized, the electricity doesn't go through. Is this not contradictory? I think that this theory doesn't fit in the phenomena. We cannot think of the light and electricity quite in the same way.

[@dusanjankovic2610]

Well, there are 2 things to consider. 1. In the first part, both the source (the lamp on the projector), and the receiver (the whiteboard on the wall), are not polarized. In the second part, both the emitter and the receiver are polarized. 2. The direction of the wires in the frame that's used as a filter is not the "direction it's polarized in". The direction of the polarized light it let's trough is perpendicular to the direction of the wires. The crudest way to think about it is to think about having narrow tall corridors pumped full of water passing trough them. If you put vertical columns in each corridor, they will block the flow of water, but if you turn them by 90 degrees, the water can now flow between the gaps (this is not an effort to explain how the principle itself works though).

[@felaran]

are there plorizers that work on the magnetic field instead of the electric field

[@dish_care]

This video explains linear polarization , due have any experiment video explain about circular polarization

[@cloggy2000]

At 2:34 Very nice big signal" of 4-5 mA At 3:00 Polarised: "Really big signal" of 6-7 mA - Why is it now BIGGER? At 4:38 "Lovely big fat signal" of 8 mA At 6:05... Wouldn't that horizontal part be smaller than the original signal... not bigger.! Especially when probabilty of fotons passing is 1/2....

[@phillmaf7319]

Fundamental mathematical expression of phase and polarity. Chirality ,the left or right handed ness of atoms is important .

[@johncgibson4720]

I don't see the anything surprising here. The metal bars are antennas that pick up signal and re-radiate the signal. Many EE graduates end up making prototypes of this type of satellite receiver/transmitters about 10GHz for mass production. Take any antenna class in a 4-year EE program and every thing is seen as antenna.

[@johncgibson4720]

You can modify the length of the metal bars to tune the impedance of the metal-bar-antenna to reduce/increase the absorption/re-radiation of it. I will not be surprised that the system has been tuned by a EE engineer already.

[@djmips]

I agree that tuning the impedance would improve things but only to make it block better.

[@McDaniel77]

The particle behavior is just seeming to be caused by a particle, in reality it's the electromagnetic interaction of one elementary charge with another. The only real object are Protons and Electron, the elementary charge.

[@HackingDutchman]

Great explanation video, that man can explain very well.

[@SCAREDBANANA]

what if you put your hand in front of that micro wave transmitter?

[@lucromel]

So, similar explanation for the double slit experiment? The end part with the probability. Or am I way off?

[@Bareego]

There is another part to this that he only alluded to. If you go by classical physics you will end up with the signal strength getting through the middle sheet in a linear fashion depending on the angle of the sheet. But this is not what is observed. Instead you really end up with a sinus value which is what you get if you use quantum physics maths instead.

[@pbp6741]

That was very well explained. Thank you.

[@TheGentGaming]

The explanation is between 1:38 and 1:41

[@SMARTYN89]

very good presentation, valuable info but easy to follow.

[@uploadJ]

But, he's wrong. Presenter presents wrong theory for why these things work the way they do ...

[@aom9010]

@wrtlpfmpf the magnetic field induces current in the wire and because of the resistance of the wire,the electric field is absorbed and causes some heat in the wire.

[@uploadJ]

No. NO antenna would work IF what you say is true ...