Humans can sense the polarization of light with the naked eye

> Haidinger's brush may also be seen by looking at a white area on many LCD flat panel computer screens (due to the polarization effect of the display), in which case it is often diagonal.

Thanks for that, I thought there was something wrong with me when I saw my yellow bow-tie neither perfectly vertical nor horizontal.

After an hour of staring at a white LCD screen,I think you will see whatever your brain wants you to see ;-)

If you have polarized sunglasses you should be able to verify those polarizations by rotating your sunglasses to see when the screens go black vs look normal.

Wouldn't amplitude just be the height of the wave, while "intensity" is dependent mostly on the frequency?

What you're probably hearing is probability amplitude, which is the product of a wave function with its complex conjugate, rather than amplitude referring to wave intensity.

If you're interested in this stuff, check out the 160 or so videos from leonard susskind on youtube on modern physics.

Light is an electromagnetic field: a wave-on-a-rope type thing except the rope is space. An electromagnetic field exerts a force on charged objects like electron, protons or even entire atoms and molecules. If you put an electron and shoot polarized light at it, it's movement will be consistent with the electric field going up and down in a particular plane. Analogously for unpolarized light.

A thin slit cause polarization the same way only one plane of oscillation is possible for a rope passing through a slit. Except what is stopping the oscillations in 'bad' directions is the interaction between the electromagnetic field and atoms that make up the boundaries of the slit.

> in non-polarized light, the "amplitude" of the light wave points in all directions

The average is all directions. Each individual photon has just one direction. But photons are not like regular objects, if you send polarized light through a polarizer that is tilted 45 degrees relative to them you don't block the light entirely like you would expect, instead half the light gets through. I guess you could interpret this as each photon having a 50/50 chance of making it though.

> The amplitude of a light wave doesn't literally mean something is oscillating up and down, right??

Yes, it does mean that. The "something" is an electric and magnetic field. Does that count as a something?

Remember that a moving electric field induces magnetism, and a moving magnet induces an electric field. So the two fields essentially induce each other, that's why light can never stop moving, or even change speed - the fields would no longer induce anything.

> The amplitude is just the light's intensity.

No. The amplitude never changes. Intensity is the number of photons. A single photon doesn't really have an amplitude that way you would think.

I actually had the same misconception about light when studying it in highschool. I though that the up/down things that the teacher was drawing on the board was not literally how it worked (transverse wave) but that it was a measurement of the longitudinal wave. I think because I knew how sound worked, and I was thinking that way.

It turns out that it actually is a transverse wave in the electric field with another transverse wave in the magnetic field offset by 90 degrees. There is a good diagram of how it 'looks' here:

http://www.photobiology.info/Photochem.html

There's always going to be a limit to how well any macroscopic analogy can possibly describe what's going on with photons and light, but some metaphors work better than others. the trouble with the 'light is a particle and a wave' meme is that people try to combine two mental images - a cannonball flying through the air, and n ocean wave moving up and down, or a sound wave moving back and forth, and get a completely weird mental image of a cannonball flying along a sinewave path, or speeding up and slowing down. This isn't helpful.

Instead, you need to extend the metaphor in a different direction. Let's keep photons as cannonballs flying in straight lines. But now, imagine the cannonballs are constantly spinning. Some are spinning fast - they have a lot of rotational energy - they rotate with a high frequency. Others are spinning more slowly - low frequency, low energy cannonballs.

Now, which way are they spinning? Some have topspin or backspin, meaning they have a horizontal spin axis; some have sidespin - their axis of spin is vertical. Others might be spinning in a spiral - as if the barrel they came out of was rifled - so their axis of spin is aligned with the axis they're flying along.

You can imagine lots of cannonballs all flying along the same path, at the same speed, but they can all have different spin frequencies, and be spinning around different axes. Amplitude means more cannonballs. Higher frequency means more cannonballs spinning faster. Polarization means all the cannonballs are spinning round the same axis. Coherence (like in a laser) means all the cannonballs are spinning at the same speed and are pointing the same way as they pass the same point.

This maybe works better as a way to layer on the additional attributes a photon has - a frequency and a polarization - than to try to imagine some sort of transverse wave pattern. It also helps you deal with the idea of 'how do different photons carry different amounts of energy?'.

But, this is just a metaphor. Photons aren't really spinning cannonballs. It doesn't explain why thin slits cause polarization (and gives you a probably somewhat intuitive but definitely very wrong explanation for why bouncing photons off a surface causes polarization, so be careful.). It won't get you one jot closer to understanding quantum mechanics (no classical metaphor can do that), but it might just help you visualize how light can have mixtures of frequencies, polarizations, and amplitude, while still being just a bunch of particles.

I cant see any bow ties :/

Yeah; I'm curious if there is anything comparable to this for radial polarization.

Not if it also works on polarized light in the sky.

I had no idea this was possible, and had never seen this effect. Of course I launch a blank screen on my phone and the effect is plain as day, I don't even have to tilt my head back and forth. Amazing!

I never thought some people couldn't.

So, they are able to see pure white out of computer screens? That must be amazingly clear.

Same here.. I have been on occasion caught staring off into a blank editor with white background and just assumed the yellow was some eye strain related thing.

Also..totally agree and I do the same: Circular polarizer for camera can ineed make some cool cloud/sky photos without drastically affecting the rest of frame.

Hackers News tend to prefer messages that contribute something new to the conversation. This is why users downvote most jokes and often even positive comments such as yours, that should have simply been an upvote of the post. However, you seem new (green user name), so that's understandable the first time.