Can we see single photons?

Light is made of photons, and our night vision is limited by the ability of our visual system to detect these photons. In some ways, our eyes approach the fundamental physical limit for light detection, being able to detect light flashes of less than a dozen photons.

This video is copyright (c) 2021 by Kerry Kim. No part of this video may be used without my prior written permission, except as permitted by U.S. copyright law.

Animations were made in Maya and Blender by Kerry Kim.

0:00 Introduction
0:37 Photoreceptors and photons
1:52 Experiment
3:22 Rhodopsin
3:59 Signal to noise
6:00 Limitations
6:55 Conclusion

References:
Hecht S, Shlaer S, Pirenne MH. Energy, Quanta and Vision. J Gen Physiol. 1942 Jul 20; 25(6):819-840.
Baylor DA, Lamb TD, Yau KW. The membrane current of single rod outer segments. J Physiol. 1979 Mar;288:589-611.
Rieke F, Baylor DA. Single-photon detection by rod cells of the retina. Rev Mod Phys. 1998 Jul 70(3):1027-1036.

[Ranstone]

I discovered the superior peripheral night-vision thing by myself, and always thought I might have damaged my high detail rental area from staring at screens... Good to know it's normal.

[GarryDumblowski]

It honestly surprises me that our eyes are so good considering how much tinier the things that are being detected are. Your nose detects entire molecules, your ears detect broad patterns in fluid current, but our eyes detect _fundamental particles straight out of the standard model._

[hipphipphurra]

Congratulations to his high quality contribution.
This deserves a million views.

[FelixHelix]

I have always experienced a phenomenon called "optical snow" or "visual snow", where there is a dull white static flashing over everything, constantly. It's faint, but especially noticeable if my eyes are closed, or the room is dark. It's similar to the effect one gets by rubbing your eyes until you see flashing lights, but constant and not as prominent. However, it is very annoying, and at times it is worse than others. It seems to pair with my tinnitus. I fully thought that it was normal and everybody experienced it until I was 16, when my optometrist had no idea what I was describing when I told him about the "faint bright white flashing everybody has".

[reinux]

That's pretty cool how the rods are off to the side a bit.
Day time = hunter mode, need to see ahead
Night time = prey mode, need to see to the sides

[kummer]

This man deserves better. Outstanding video.

Many people like him deserves better in the industry. His high quality, humble approach and coherent exposition granted him that opportunity.

[denispol]

As a visual astronomer, that was very compelling for me.
I read a similar russian paper that was published in the soviet era.
So, comparing the human eye to modern astronomy cameras, with their quantum efficiency of ~70%, the cameras have surpassed it.
Also, once rhodopsin detects a photon and starts a chemo-electric reaction that leads to neuro-signal, it has to deactivate, and it takes time. Also, unlike the cameras, there's almost instant exposure time.
While the camera can collect light during long exposures.

[victorcercasin]

I love when people explain things in an objective, deep manner interest of making dumb analogies Ana simplifications
Great explanation

[arseniix]

Haha, finally you've gotten appreciated by the algorithm, congratulations!
Remarkably great video.

[therugburnz]

I learned in Astronomy that I and most others can see better from the sides of our visual field. Yes, 20° of angle sounds correct. I'm partially color blind and notice it well. I was doing a visual observation of a nearby galaxy. I could not see it at all until I concentrated my attention to the sides of my visual field. It made it difficult to draw until I was instructed how to "see" from the 20° position.

[oceannuclear]

Thanks for providing the actual timescales and the graphics! It's very useful for figuring out what's the true timescale over which things happen.
I'm also surprised (but probably shouldn't be) that noise suppression is a problem that plagues cameras and biological creatures alike!

[jamest.]

I woke one night a couple years ago, because it was so hot, it was hot because the power was out, in the whole small town I live in. I went out side, it just happened to be a very clear sky, and no moon, I could see stuff I never saw at night, and the stars, the sky, it was amazing!! It was like a spiritual experience, I couldn't stop looking at the sky, I could see 10x more stars than usual, and alot had a. Red orange color to them, it was crazy, nothing was normal! It makes me want to move to the middle of nowhere, and just look at the sky, my eyes were adjusted as much as possible to low light vision, because I had been sleeping for hours, and no lights to foul my night vision, the only light was the natural star light, and the light pollution from towns probably 20miles away, the night sky is far from darkness, we dot realize that so much anymore, I'd love to see that again, especially with binoculars... It's amazing how much light there is in the night sky! Great video!!

[skyman]

The fact with the radio telescope blew my mind! I never thought about it, but it is unbelieveble how less energy a low frequency photon carries.

[krzysztofjakubiak]

A very eye-opening video.

The explanation and delivery are both excellent!

[alitazabekov]

Wow, what a nice explanatory video! I see so much work put into these animations - and they support and complement the narrative really well!
Thank you so much for this video! I wish there were more of such quality videos!

[Roberto-REME]

Excellent video production Kerry, and you did a great job presenting the information in an interesting and engaging manner. Your narration is superb. Well done!

[gizfpv]

Very good video. Nicely presented. Fun fact (that you may or may not know), night vision headsets that are used by the military always show images in green because (as you mentioned in your video) rod cells can see greenish light better than any other colour :)

[labibbidabibbadum]

I'm glad I found this channel. Delivery and content are perfect.

[tjeepert]

I have just discovered this video and I already love it. This is some serious quality stuff

[lumi]

this is surprisingly high quality, especially the scripting and narration. the answer to the titular question is also satisfactory