What Happens When Light Shines on Photochromic Glass?

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I show you how photochromic glass works
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[@Buttonpusher42]

In college after walking to class in the winter I would run one lens under warm water to turn it clear, and then enter class with one lens in sunglass mode and the other clear... I'm still a weird kid, decades later

[@JohnDoe-qz1ql]

😂😂

[@Chaoscelus]

totally epic poggers anime moment

[@Warhawk76]

Nice! Sounds about right to me.

[@ahha6304]

so lucky I use 4711 to clean it, eh, I mean just plain water and few soap, but 4711 part was true, just not often and only outside my house

[@ahha6304]

@@Chaoscelus CASE CLOSED

[@Ninja20704]

I learnt about these glasses when I was first learning about redox reactions. It’s always nice to see what you learn being used in everyday items/processes.

[@sushilkumarlohani6709]

I am also learning it right now.

[@animekaadda2330]

Really dude? Like i do know whats redox reactions but this thing was cool

[@Avicerox]

Same

[@pradipseth2291]

Shouldn't Copper reduce Silver. Here Silver seems to reduce copper ions...? I'm confused.

[@db8823]

Owned these types of glasses for years. The older one would never return to totally clear and end up being dark all the time. The newer ones seem to be better now. Very interesting tie to glasses and film. Thanks

[@OGSontar]

I've worn glasses since I was around 4. I'm 61 now, and even after dual cataract surgery, I still wear them. For like the last 20 or 30 years, they've always been photochromic, but honestly I can't even remember when the last pair of 'glass' glasses I owned. Now, prior to my surgeries, actual glass lenses would be as thick as a glass 32 oz. coke bottle bottom (or 2), but now they are so damn thin it's unreal (for me).

[@moonandtanu7591]

They are that big? Wow

[@OGSontar]

@@moonandtanu7591 Heh, that was hyperbole, actually. That being said, I was told years and years ago that I could no longer have glass lenses due to the thickness required. Plastic lenses have a better ability to bend light than glass ones, thus are thinner for a given prescription. I believe the property is called the index of refractivity. Even so, my lenses were getting pretty thick. Each new material developed for lenses made them a bit thinner, but the progression was clear. Due to cataracts, I had lens replacement surgery in both eyes last year (2021), and now, even without glasses, I can see better than I ever could with glasses, and _with_ my new glasses, my vision is almost 20/20.

[@coriscotupi]

@@OGSontar I also had lens replacement surgery in both eyes due to cataract. After the surgery, something interesting happened: although I still use glasses for reading, my sight at medium distances (a few meters) is now 20/20. For everything indoors (except reading distance) I no longer use glasses. For very long distances (like reading a sign half a block away on the street) it does feel more comfortable with glasses, so I use them for driving.

[@OKtheChannel]

​@@coriscotupi That's fairly rare, but not unseen. I suspect your natural vision, after the surgery, is somewhere around -1,5. If you had your natural eye lenses removed due to cataract. then you typically need to add +3,0 to your natural vision for close distances. so that would put your far away vision at -1,5. and your reading vision at +1,5, while it would put your mid-distance vision at exactly 0. So, for the road you need glasses, for reading you need glasses, but in between you don't.

[@coriscotupi]

@@OKtheChannel Good info, thanks.

[@mraymo1977]

I recently got photo-chromatic lenses and another interesting thing is that many windows have something on them that doesn’t let UV light pass through, so they won’t get dark if you’re looking out a house window and in the car.

[@OKtheChannel]

Yup. Photochromic lenses react with UV light to get dark. Glass as default already blocks most UV light. New, UV protective car window glass blocks all of it. However, there is a type of Photochromic lens that can help with that. One of the brands i know is Transitions, and they have a photochromic chemical they call XTRactive. XTRactive photochromic lenses don't take UV light only to get dark, they also use a little bit of visible light. So, these lenses can get to about 50-60% dark when inside a vehicle.

[@AldjinnTV]

@@OKtheChannel I don't recommend these unless you want your lenses to be mostly sunglasses, as they rarely are completely clear. Great for lightly photophobic people though.

[@OKtheChannel]

@@AldjinnTV Actually, i wore Photochromic Lenses most of my live. I recommend transitions myself, as it's a brand i know, am familiar with, and i know their tech is good. I don't see any problems with them staying clear. Indoors they always are perfectly clear.

[@AldjinnTV]

@@OKtheChannel I am talking about the ones that can get dark without UV light. And I am not giving my POV as I have never wore them, but my clients' POV, as i've been doing that for almost a decade and have accumulated enough experience and sales to understand my patients/clients needs. Obviously nothing is absolute and some people stand out from the rest, but you are the minority and shouldn't recommend technical things to the majority

[@OKtheChannel]

@@AldjinnTV Ehhhh, you realise that technically you are obstructing options from some of your clients? Xtractive lenses are not some technical product that is recommendwd only for engineers or something. It's meant for the general public. You don't have a transitions preview set, so that you can show them and tell your clients exactly the pros and cons of Xtractive lenses? Seems to me like it is better to keep your clients involved and informed, than obstructing them from some products because of my own experience.

[@stickinug]

Fascinating! I've been wearing photochromic lenses since I was a kid but I never knew how they worked! This is by far one of my favorite inventions of all time. They are an absolutely invaluable accessibility aid for me!

[@WhuDhat]

this will be a fun trick you can now show others

[@OKtheChannel]

Want to know another fun activity? If someone tells you they bought sunglasses super cheap, you can actually use your photochromic glasses to check if they really are wearing protective sunglasses, or if they've been scammed and their sunglasses are actually dangerous. . Simply take your glasses, place them behind the sunglasses in such a way that only one lens is covered with the sunglasses, while the other is exposed, and take the entire setup outside under a strong sunlight. The exposed lens should turn dark, while the lens that was behind the sunglasses should stay almost entirely clear. Then you know that the sunglasses are more or less the real deal. If the lens behind the sunglasses turns dark, then these sunglasses should be thrown away.

[@ashvw]

This was really cool! I always wondered exactly how my glasses do that. Thanks for another great video!

[@meomuop3649]

bot

[@ashvw]

@@meomuop3649 You think I'm a bot? That's funny right there.

[@TrashBox09]

Don't try this while wearing the glasses!!!

[@TechDeath91]

Too late 🤕

[@Matticus289]

The laser gets blocked. Do it with the glasses on and the laser beam won't reach your eye

[@kevinperron5767]

NO YOU CANT TELL ME WHAT TO DO!!!!

[@ZOCCOK]

You will get a permanent effect 😂

[@THESLlCK]

Thank you will

[@jasonboldt9918]

Really awesome Video! I'm in the optical industry and this is more informative than most of what we get. My only issue is that glass has become nearly nonexistent and we use different materials for the lenses. Also it was only mixed in with one, now defunct brand of lenses, now it's a sandwiched thin sheet between the monomers or polymers used. Again though this was amazing

[@diavalus]

I had new glasses being made two weeks ago. Now it makes sense why the guy was so proud of being able to offer glass lenses.

[@anupew3276]

could you as someone from the industry elaborate on advantages/disadvantages of glass (or different kind of glass) and polymer layers? As a regular consumer with limited chemistry knowledge I dont really see why glass would/should be preferable (heavier, more fragile, probably more expensive)

[@diavalus]

@@anupew3276 I can give you some of the details I was told when I had to choose mine and were explained to me by the technician: glass lenses scratch harder, have a bit better clarity and they are also easier to wipe. As for the price, I had to pay 200 EUR for glass, while the plastic ones were 150 EUR, so it was not a big difference in price. I assume most people won’t care about these things and will choose plastic lenses, instead of glass. However, I am happy with my choice even now. Did both glass and plastic lenses for two frames and while the difference is small, I can notice it.

[@anupew3276]

@@diavalus thanks, well as for clearing i would expect both to have at least anti-flaring coating (simmilar to lenses for camera), probably some de-haze coating as well so that should be same as surface layer is the same on both. Hydrophobic coating to help cleaning exists too, not sure if that is used on any glasses (its not that uncommon on photography filters theese days) Also those coatings scratch easier than both main materials (at least from my experience with said camera lenses and filters for them) but thats a fair point. In my activities I am also concerned with resistance to breaking on impact which I would suspect polymer should be a bit better at. But im not sure, hence some pros/cons list from someone in industry would be nice

[@knivesron]

i swear this guys videos are really good at explaining things and its all cool experiments that he does.

[@safe899]

@The Action Lab can you please fry a popcorn under vacuum and measure whether it has become larger on average than a normal popcorn under normal air pressure? I think some companies use this trick to make exceptionally larger popcorns, but I'm not sure.

[@deadweightnero]

you can ping people with youtube comments?

[@FrozenBusChannel]

@@deadweightnero why not

[@shoopdawhoop]

I am curious if the photopolymer in the glasses is dense enough to store a short-living interference pattern, and if yes - is it able to store a short-living holograms that can be observed by eye? You may try to make a shine-through hologram or Denisyuk hologram by shortly exposing the glasses to the laser beam with close enough object to record a hologram of it on the glasses and to see how long it lasts

[@LIOTBs]

You always do a good job. That was really cool to learn about that. It would have been really cool to have another animation to go with the photography example. What really would have been cool is to have a b-roll of you and your wife working on that painting during your describing it. Or at least I have a picture of it when you were talking about it.

[@xHansax]

If only this reaction was way faster, would be good for driving in and out of dark tunnels on a sunny day.

[@CZghost]

I was wondering how self-darkening sunglasses work. Thanks, now I know it.

[@mlbrown113]

Great video. Been wearing photochromic glasses for decades and never new how they worked. However, going to movies in cold weather, I had learned the hard way to get there early in the winter if I had to choose between out of focus (way out of focus) or too dark to see.

[@Speeder84XL]

Put them inside your jacket for a few minutes before the movie starts would probably do the trick as well (since they apparently only need to get up to room temperature or slightly above, to get clear in a few minutes), haha. But interesting glass. I didn't know about it at all.

[@avgfunkygamer]

That explains why my glasses stay dark longer in the winter when I’m going back inside.

[@heathlatter2218]

These glasses only react to a specific wavelength of UV light, which unfortunately is blocked by most car windshields. I work in an underground mine and when I come to the surface, to activate them I roll down the window and hold them to direct sunlight for a few seconds.

[@QxDEADBEEF]

It would be interesting to know after how many times of darkerning and clearing they would last before the quality of the glass is decreased. For example artifacts on the glass might appeared.

[@mandlikprajwal466]

Theoretically this should not happen but practically donno

[@bellablue5285]

I've had the same lenses for well over a decade and never noticed any issues (my rx never really changes), granted brand of lenses might have differences, but my Transitions I've never run into weirdness with

[@DoctorNemmo]

Honestly my glasses broke way before I noticed any degradation in their photo chromatic properties my dear fellow

[@naB4o]

It depends of the technology of the photochromic lens. Either is resin with mass reacting, or its a Transitions lens with a bettter tinting effect. The newest ones Transitions GEN8 stays clear for longer period.

[@ryana4369]

After 2-3 years they tend to start keeping a residual tint when the should be clear.

[@Phillip_Duck]

I wear glasses with a photochromic coating for my light sensitive eyes. They're nice :) I found out about the temperature effects when I noticed they stayed dark longer in the winter. It's really awesome to know the science behind those lenses now, thanks!

[@muhammadlawan7045]

Finally I've been looking for such explanation of this lens but couldn't find a better one. Thanks

[@appleuser1882]

Jihadi

[@goiterlanternbase]

I have a riddle. One i had such a glass, together with a piece of thermal printing paper, in a pocket. Where the paper touched, it darkened the glass heavily. Yes, the paper is bright white, but all of that happened deep inside a metal locker.

[@RogerArbogast]

I wear photochromic glasses since 27 years, and I never knew (nor asked) how they work. Thanks for that explanation 👍

[@meomuop3649]

since

[@manitverma4425]

I've been wearing these types of glasses for the past 5 years and didn't know how they work until today! Thank you!

[@lioniate2917]

That's my man doing things I never thought cab be possible

[@mountainhobo]

Tried those lenses in the past, they would never get dark enough in the California sun, so I have resigned myself to carrying two pairs.

[@allymaine]

You should try the glasses with clip-on!! They are really cool and you don't need to buy another pair!!

[@mountainhobo]

@@allymaine I've searched for clip-ons. Alas, they do not seem to be popular anymore.

[@allymaine]

@@mountainhobo yeah... when I bought my new glasses they had only 4 options with clip-on :( But it was/is really nice, bc sunglasses can be really expensive when you have myopia and sometimes we can't afford two glasses.

[@OKtheChannel]

Next time you go get glasses, do ask at the store if they maybe have a Transitions presentation set and a UV lamp. Photochromic technology is actually moving incredibly fast, and now, especially with the transition GEN 8, they can get extremely dark, up to 92-95%.

[@OKtheChannel]

@@allymaine You should look around other optical stores. At least in my area, Clip-ons are getting quite popular again, so we have an entire shelf of them available : D

[@MrFlaviojosefus]

Hi Action Lab. Fantastic video. It turns out that the glasses I am wearing right now are this kind of glass. I had a completely false idea of how it works. Thank you for clearing this up for me. It is a pleasure to know exactly how it works.

[@keithyinger3326]

I wear glasses with photochromatic lenses and I have noticed in the winter when I come inside, it does take longer for them to lighten up again.

[@chrismerklin8460]

Maybe The Action Lab can follow up with a short video trying a few photographic exposures on the lenses!

[@gamebugz-blockstrike842]

This guy never runs out of ideas!

[@ghostmanscores1666]

This was one of my favorites. I've been fascinated by that since i was young.

[@2nd-place]

I always wondered how this works. Thanks!

[@YounesLayachi]

I have been interested in these kind of glasses for a short while now, the timing of this video is impeccable :D

[@maurofabris6527]

Great Video!! Where did you get that violet laser?

[@paulbrooks4395]

This is super cool, I immediately wondered how this related to photochromatography.

[@Linus007]

Great video. I have been wearing these type of glasses since 1980. I learned something new about the laser and the copper ion. Thank you.

[@Smile_its_a_good_day]

How does atoms move in solids ? What define their movement and for how long they can travel in solid medium ?

[@nid274]

I was wanting to know how the transition glasses worked and now I know it. Thanks!!

[@MarcoVenustus]

I wonder if you could 'print' a picture on those lenses by using a dark room with a small hole on it

[@ericrbacher9371]

so i just ordered a pair of glasses like this about a week before this video dropped. nice to get my questions answered before i even tried to look it up! i do have a question remaining: there were 2 color choices. one was grey like in this video, but there was also a brown color. what chemicals need to be in the crystal to make it brown?

[@alikayar429]

i also wonder if they can have different colors with various chemicals. But currently only two colors available

[@jaycal1920]

achieves their photochromic properties through the embedding of microcrystalline silver halides (usually silver chloride) in a glass substrate.

[@matteo234321]

I always hear "Hot water freezes faster than cold water" I'd love to see a video demonstrating why this is!

[@praisethyjeebus]

@@dtylerb Considering the hot water would have to cool just to get to the point of being cool water before freezing, I think it would actually increase the time it takes to freeze

[@GuillaumeLT]

That been observed in nature but never replicated in lab. Check "Mpemba effect" for more details.

[@kyles5513]

Think it has something to do with how the molecular behavior is at higher temperature that allows it to freeze faster, I guess kinda like how boiling water instantly turns to snow if you toss it outside in -30 Celsius weather.

[@Anivacuum]

Not all photochromic glasses are made this way. Zeiss uses organic photosensitive molecules that unfold under UV and absorbs more light than in folded form.

[@4r1ga70u]

very nice explanation. thank you very much!

[@mandlikprajwal466]

Okay A basic question Why will photos or light hitting glass initially will knock electron from chlorine inspite of being electronegative It can knock electron from silver and give that electron to chlorine making it more stable

[@moonandtanu7591]

Chlorine in anion form is electron rich.

[@JanKowalski-rd7yb]

I've been wearing those for years, thanks for explanation! But I'm also curious, what makes the difference in color of photochromic lenses, since for a long time, there were only two colors available: grey (black) and brown. Since my eyes were getting tired with brown ones faster, I was mostly going with grey, when choosing new glasses. But nowadays, you can also choose green (it's more of a "dirty" green or grey-green) or blue. Currently I'm wearing blue ones and I'm quite satisfied (though drivers shouldn't use those). I'm assuming that the technological process to create such lenses has to be quite complicated, since for years there were only black and brown available. Also, while my glasses become clear indoors very quickly, I actually noticed too, that this takes longer time, when it's cold outside.

[@MrScorpianwarrior]

I would imagine it is some other doping agent, or possibly different levels of silver/copper atoms to give it different optical properties. As a film photographer I was wondering briefly if the color could possibly come from the same color process used in color film developing (as it is the same chemical reaction) - but color film actually turns into dyes when reacted and I can't see that working in glasses.

[@JanKowalski-rd7yb]

​@@MrScorpianwarrior I was doing a lot of photos with analogue cameras in my time (though just for fun, I'm no professional), and I still consider classic film (even 135, or 35 mm) to be vastly superior to digital cameras, with their matrix noises, some problems dealing with the brightest and the darkest part of the same picture, and horrible reaction times. I mean there "are" good digital cameras, but with ungodly pricetags (for me, at least). I was mostly going with Ilford PAN films, ranging typically from ISO 50 to 200, for when I wanted some "ambient" black and white photos, then I often had these developed on barite paper for that "brick" shade of dark red. I would also often force the film, in order to get this rough grain, so in the end it would give me this "vintage" look of the final photo. I was always saying, that color distracts from the actual object of the photo, but when I needed to use color film (like for my friend's wedding), I was mostly using Fuji films, sometimes Kodak Portra, though I never liked the "standard" Kodak color films - the colors in those were too saturated and unnatural, in my opinion. I fiddled around with infrared photography too, also using B-W Ilford films; sadly I never got my hands on IR color films or proper Wratten red filter (I barely managed to find some Hama red filter), as I'm based in Poland, and IR films were super hard to get (you would have to import them from Germany), then digital cameras rolled in, and all demand for classic films suddenly died... Anyways, I think that the usage of copper in those photochromic lenses would make sense, given different oxidation states, which would explain both green and blue tint.

[@Chicano_pistolero]

I ALWAYS WONDERED why my color changing glasses would take SO LONG to go back to normal during the cold season lmao

[@robertk1701]

Was literally googling 'silver chloride film' seconds before he mentioned this being the same process used in film. Knew there was at least a type of film that involved silver. Thanks Technology Connections.

[@Benm8_]

Hay I found a cool thing with soup bubbles/foam where if you put the soap in a container and put it under water it reflects light like a mirror

[@dooski22]

They use this tech for motorcycle helmet visors. You can do the same thing with a blacklight.

[@The_Slavstralian]

So these are what local glasses companies in Australia call Transitions Lenses. For those wondering.

[@daemonsilverstein8633]

Local glasses companies here in Brazil also sells them as Transitions Lenses ("Lentes Transitions"). Transitions is a worldwide company that holds patents for this type of lenses, AFAIK.

[@alexandrudanciu7874]

Enjoying, you're wander ??? This was a mind boggling explanation- I'm so happy that I'm contemporane with a great physicists that take his time and energy to care and explain all of this. These are secrets of nature that enlighten the human being in the natural process of becoming wiser and wiser to each passing day. Thank you so much for this quality video!

[@RealCadde]

Are there window panes with this feature? Imagine that no matter how bright it gets outside, the inside is always illuminated the same amount during the day. Would be really helpful in office environment where sun glare makes it difficult to see a computer screen.

[@TheFarmacySeedsNetwork]

Very interesting! Thanks for another great video!

[@gangaprasadyadav5046]

Very well explained 👍🏼

[@pedrosoares9470]

So cool and easy to understand.

[@gerrygarcia943]

What type of careers would involve the development of these types of glasses? Would this be a combined effort of engineers, physicists, chemist and material scientists? Which scientists would be primarily involved in the development of the glasses and the science behind them? I’m looking to shift my career as a science teacher, and this topic seems so fascinating! Any help would be appreciated!

[@becca40552]

I've been dyeing to know how these work since I got my first transiton lense a couple months ago. Thanks for making this video!

[@heromahdi]

i have these photochomic glasses, pretty useful cuz its always sunny where i come from.

[@kennethultimate02]

Nice! I'm contemplating whether to but photochromic eyeglasses or not

[@daemonsilverstein8633]

I have this lenses, previously I knew it as "Transitions® Lens" as that's the name that the Optics store sold me these lenses. It's vital for maintaining eyes healthy amid so many artificial and natural UV lights.

[@swiddle1]

I was totally expecting this video to be sponsored by Transitions Lenses.

[@OKtheChannel]

Well, it is understandable. Transitions is the name of the company that makes these tinting materials. Many lens manufacturers work with them, and as far as i know, they are the best on the market.

[@BazilRat]

As someone who wears a set of these I was curious as to how they worked!

[@MUTHU_KRISHNAN_K]

What if we shine gamma rays on the glass?

[@stalkerspike]

I thought it was the "fixer" solution that makes the process in developing black and white film and prints permanent. Also that it washed away the extra silver which is why some companies recycle silver from old fixer solution.

[@pety200]

I didn't really get the part to be honest where the Ag with no charge at the edge of the crystal structured trapped in that state would start to form an all Ag partition. Why snd how would an Ag attract other Ags to form such a partition in a solid-crystal compound?

[@SpeedRunningStartups]

youre such a friking genius

[@fmaion]

Hey, make a video with an apparatus to "take a picture" with this glass. Just put inside a black chamber (can with a pin hole), and point the whole to a place with sun. And go inside and see the "photo" on the glass. Does it work?

[@jerryfacts9749]

The optometrists here call there types of lenses photo-grey glasses. I wear prescription glasses that are like this. The ones I wear are neutral when tinted. These can come with different types of tint.

[@ragingwillie483]

very interesting, and well explained. thank you

[@brfisher1123]

Wow, for the 15 years I've been familiar with transition lenses I never would've guessed that temperature made a difference in the rate that they turn back to normal after darkening!

[@liambohl]

Most chemical processes happen more quickly at higher temperatures!

[@mcv2178]

I did not use a laser, but sometimes I take my glasses outside with stars or other shapes masking the middles of the lenses. Then I take them in and have Elton John glasses for a few minutes!

[@nils12453]

But when the Copper-Ions give an electron to the clorine-ions , why don’t They lose it again like before because of the light ?

[@auntydoll8]

Color change in a range of energy need to move the ion. It is often linked with the WaveLenght of light we need to block. Idk, 205nm ?

[@mandlikprajwal466]

Energy should be equal to ionisation energy of chlorine

[@vladiiidracula235]

I have a pair, absolutely love them! No need to carry around an extra pair of sunglasses lol

[@robertzarfas9556]

I would love a deeper dive into how developing film works. I’ve always wanted to understand it 😊

[@joshuagibson2520]

It's been covered ad nauseum. Do a search.

[@teutonvmis24]

Nice video, as always. Where can I buy those glasses?

[@nugboy420]

I knew this was related to photo development the second you said silver ions lol.

[@carlbrenninkmeijer8925]

so clear, thank you°

[@prateekchauhan3865]

Please try to explain all famous perpetual motions😊

[@NiffirgkcaJ]

My sister got these glasses, and it's so cool~

[@MARZ1911]

We used to play with a glow in the dark Frisbee....throw it up in the air and try to hit it with the violet laser pointer (night time if course)

[@kyokoyumi]

As someone with transition lenses, I knew immediately that's what you were talking about when I saw the lazer xD

[@justayoutuber1906]

WARNING: Please don't shine the laser into the glasses while wearing them.

[@OKtheChannel]

Or at other people wearing them.

[@diamondkeerthibalan99]

Hi , I watched all your videos , each one is awesome, Did you ever try to sent high temperature gas/steam in vacuum chamber?😀😀

[@mikerhinos]

Thanks a lot to take time to make 4K60 videos

[@BazilRat]

I prefer them myself, but I totally understand how that might drive someone mad.

[@tnb178]

You could create a hologram with that stuff!?

[@richardlilley6274]

Thank you for sharing

[@Kim_Miller]

I had photochromic glasses for a while but I ride motorcycles and the helmet visor stopped the glasses from going dark. So I'd be riding in bright sunshine with photochromic prescription glasses and having to wear sunglasses over the top. I only got them that one time and when the prescription needed updating I went back to standard. However, they were entertaining to fiddle with through meetings etc where I'd put my finger over the lens and hold them in the light so they'd colour up in patches. Still a kid in an adult's body. 🙂

[@Backkward]

What a silly goofy prank to do with your glass-wearing friends when they least expect it! I'll be sure to point a lazer directly into their eyes! :D

[@OKtheChannel]

Yeaaah, considering glasses don't seal around your face, i would not try that. One wrong angle of the light and you have yourself a very, VERY expensive prank in court xD

[@tresnoscope9371]

this is really awesome video. anw is it true if you put salt on hand sanitizer can burn toilet paper? pls do the video.

[@vernonzehr]

Wow. Would be interesting if you could get a larger flat sheet of photochromic glass and "develop pictures" on it. Shinning light through a photo negative.

[@fullofbullets58]

I subscribed to you when you had only 200k subscribers... And your content was amazing, and it continues to be amazing.. Thank you for what you do! You teach a lot of people things in an amazing way.

[@wobblyrick6255]

thats cool i had some as a kid the school broke them telling me they are sunglasses and saying i was lying about them being prescription

[@thibaut5345]

Where is this school? North Corea? Russia?

[@Zantrop64]

I've had glasses like that, but I'm done, they're ok with a little light, but with my hypersensitivity to light, pretty useless in the sunshine. I'm on my 2nd gen of clear *and* sun prescription glasses

[@918Xander]

I'm curious if it's the cold from the ice, or if it's the white of the ice reflecting more photons back to react more, causing the spot to appear longer...

[@mikebel74]

That was the best explanation I’ve seen of this phenomenon. Great work! I wore PhotoGray glasses in 1974. I know, OLD. That was before KZbin or even James Orgill. Keep up the great work. You make the Internet shine, like we all thought it would in the 1990’s.

[@grekygrek]

He really does 100% have the essence of young internet days. The eagerness to spread facts and some theories, and all the while transcribing the explanation into something palatable for the average bear lmao. I am sad now, he is an icon of an older age, and im young, born in 93, and the world today makes me feel like i have lived centuries before them. People are so complicated and unhappy.

[@LiborTinka]

@@grekygrek Remember the "world" or the internet is NOT what you see on Facebook or KZbin. These are just centralised mass platforms. I've used internet before both these giants and it is pretty much the same if you dare to step outside the comfy mainstream websites. Like hobby forums, blogs etc. There are wonderful decentralised social networks, video sharing platforms and heck the community around Lightning Network is growing like crazy. And what's best, these "fringe" areas are occupied by similar people to those who used internet when it was a technological novelty.

[@anthonyleggio4877]

Is this the same or similar technique that welding helmets use to darken their shade?

[@dittocopys]

Hey action, how long would it take to dry clothes using a vacuum chamber?

[@logically1028]

Hey man..would buoyancy effect work in vacuum???? Without atmospheric pressure??

[@jordvn.exe_]

Optician here... are your photochromic lenses actually glass? Actual glass lenses are uncommon in the optical industry nowadays. CR-39 (Plastic), Polycarbonate, Trivex (a urethane-based pre-polymer), and High Index (Plastic with a high refraction index, usually 1.67 or greater) are typically used instead of actual glass.

[@TheSmkngun]

Why are glass lenses getting replaced by plastic?