Retroreflectors; they're everywhere, and they cheat physics (sort of)

Opublikowany 31 sie 2020
Road signage and other markings may be something you take for granted, but have you ever wondered how they can appear so brightly with just the output of your headlights? Find out how, and get a load of other trivia, in this video!
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  • Thnx for another great videos. And also thank you for bringing up some road signes is blindingly dangerous. Same here in Sweden as in what ever english speaking country you reside in, indicating this is a world wide problem. On a "reflective" side note, presumibly, LED based roadsigns is a new problem. Where i live, its really dark during winters, and in between cities it's almost pitch black.... and then comes a daylight experience informing me about some festivities that will take place.... gee thnx, i hope i will live to see it, because i won't see properly for a distance now. I hope deer's don't like the same events as humans do, and since i don't see people dying exsesivly there, i guess not even a moose want to go there. 😊 But if you really wanted to kill somebody, place something low-reflecting after a sign like that and.... bam.

  • Yeah! Beta tapes! Woo!

  • so when do we start putting these on cows....

  • Me: listening passively while folding laundry “This is a cat.” Me: 👀

  • 21:14 Sadly it has become less about the process and more about beating people with the result we like.

  • That's a good looking kitty cat.

  • My dad was a trucker for many years and I asked him about it and he said it's not very hard to see those signs in the night

  • We love our 'cats eyes' here in the UK - very clever things and great for lane marking (with colours too)

    • Oh, I also remember being in Norway in the winter and all the school children had retro-reflective discs hanging off their rucksacks so they could be seen in the darkness on the roads as one drove through towns and villages. Very sensible safety feature.

  • 18:00 Easy solution. Add reflectors to deer and moose.

  • Amazing knowledge, although, I might have to test that 3 dimensional orthogonal mirrors thingy on paper and see if it would really work

  • "This is a cat" Can confirm.

  • I wonder if that hexagonal tape is vacuum formed and like thermally set or UV set plastic. Like how they make bubble wrap but on a microscopic scale.

  • by meters and kilometers you mean yards and miles

  • I used a whole bunch of retro reflective tape as hidden decorations in a haunted house I ran last year. Big scary wendigo monster effigy next to a tree doesn't look scary enough? Try taking a picture of it with your camera, bam! Brightly glowing eyes staring right back at you.

  • @13:31 This is a cat..... Me: Hmmmmm...... I wonder if he's going to stick reflectors on it?

  • Thank you for such an interesting and informative video. One question that comes to mind on this - why do some signs (speed limit, etc) appear prismed/rainbow depending on how the sun hits them? Is that a function of the retroreflective coating and weird sun angles?

  • At 11:34 shoulda added a shit eating grin and a thumbs up. The rant starts around 11:00 not gonna edit to be exact it but ends with a good sentiment. lol Edit it’s start is at 11:19 only did this cuz I was way off lol

  • I suspect they don't use retroreflectors on garage doors because it's beneficial for the beam to be easily broken by orientation. The sensors are usually mounted to the track the door rides in, not a solid base. So if something goes wrong and a track goes out of alignment, the door will be stopped same as if it was obstructed.

  • Whew, I thought we were going to go a whole video on retroreflectivity without a mention of the retroreflectors on the moon. He forgot to mention how they can be used to dispel the false belief that we never went to the moon.

  • Ok having grown up in the country and now living in the city because of school and work, the sound of nature at the beginning of this video was almost a sexual thrill. I didn't know how much I missed that sound.

  • Want more of that beautiful cat.

  • I'd like to make a note on turning on your headlights as a truck driver....if you don't, we may not see you in the water spray coming off the tires. Seriously. It can be extremely hard to impossible to see you.

  • 20:00 Are you perhaps thinking of Moiré Patterns?

  • This is my favorite channel

  • I bought a retroreflective keychain for my backpack, its cool but also cheap

  • you're blamming people who thinks they car has automatic lights, but I know a person who only turn on the car lights when he doesn't see a thing, and if he is in a traffic situation in a road with no light he may go without lights.

  • Cat eyes

  • I love this video but the opening always makes me INCREDIBLY nervous. I ride a bike for my main method of transportation and these sorts of dark roads with turns were always the worst parts of my commute... luckily I live a lot closer to work now and there's a sidewalk across the entire route there

  • The term "retroreflection" is fundamentally incorrect. Someone didn't understand what "reflection" means. But to understand this you have to be a bright guy.

  • Fun thing to do to a friend that is an arachnophobe: give them a bright LED light that can be worn on the forehead (on a headband) and tell them to scan any grassy or wooded area at night. At least where I live, I can see 100's if not 1000's of retro-reflective spider eyes! You can verify this by picking any light and homing in on it. It's always a spider! My wife was walking with me and thought I was hallucinating because she couldn't see what I was describing. Until she wore the light, then she could see them and I couldn't. The distance between the light and your eye must be VERY small (only a few inches) for this to work.

  • In my job as a paint chemist I formulated retroreflective paint for use on railcars. The tiny reflective beads used in the paint had a weird property: they were extremely slippery. A tiny amount spilled on the lab floor turned it into an ice skating rink.

  • Every railcar in America has a bunch of retroreflectors on it, because it occured to railroads that only about half of the crossings in the US are protected by an active signal, and so people would try to drive through passive crossings that were already occupied by a train. Of course, yellow lights zinging by at 50mph won't stop people driving into the side of a train, but at least they also looks kinda cool at night Also, here in MN there are white reflectors on the right of divided highways, placed every tenth of a mile. Not sure what for, though

  • Pointless conversations 👎😡

  • In Australia it's a rail work regulation requirement that an X is marked on the back of hi-vis shirts to indicate that a worker is potentially facing away from oncoming... Trains. I actually don't think I want to know how that became regulation.

  • I would say these road signs are doing their job a bit too well, forcing me to turn off the high beams in order not to blind myself :(

  • I'm comment 6,666. 🤗

  • This dude needs to cut these videos down in length by at least half. Nobody wants to watch 22 min on why street signs are reflective.

  • interesting thing, look through the back of a cube based reflector and you will see in 3 directions at once, its trippy!

  • Now I know who's outbidding me on all the t-shirts I want on Ebay

  • 16:04 The honeycomb structure is for fastening the upper part which contains the reflector to the lower part. There needs to be space between for the reflectors to work. You can choose virtually any structure but it needs to be a closed pattern - not for instance dots. Otherwise condensation and water vill creep inside the whole area and render it useless..-

  • sir, what is your feline void's name? i must know....

  • I usually just listen to these while I'm driving, because driving. So, even though I've listened to this one a couple times now, I literally just saw the fantastic face you made in the mirror, thank you for making my day!

  • The mirror shot made me giggle like a school girl 😂😂

  • Drivers that can't work out how to operate headlights blind the rest of us with their daytime running lights at night, and they are also blinded by their own dash lights in full daytime mode, making them even more dangerous. You can see them squinting down the road like they're doing a Hans Moleman impression. Idiots.

  • How would most people know about the red lane markers on the other side? I personally have never went the wrong way on the road as I only DRIVE when in the driver's seat and watch for hazards. Even in my rear view mirror I haven't noticed red from the headlights coming from the other direction. I understand the fact that the light source isn't coming from my car, therefore it would be difficult to see, but in my experience there is usually a blip of light that bounces around as bumps on the road can throw light in different directions causing an interval where light can be seen from other angles. I am going to see if Canada uses those where I live. Having lived in the USA for most of my life I haven't noticed....very cool! BTW, you have to be one of my favorite presenters on these subjects and love how it takes me back to the 80's when I was a kid. Thank you and keep up the awesome job!!

  • Totally flippant comment: your hair is totally cool at 2:11, do that more often!

  • 4:19 except for water (polarization)

  • You need to take off on more insane rants.

  • 11:18

  • 3:45 My nightmare moment.

  • If only moose would start growing retroreflectors in their fuzz.

  • My favorite is when people turn off automatic headlights

  • Elvis Presley of science and education ❤️

  • Have you ever seen the Tilt 5 augmented reality table? It has a retro reflective mat that special glasses will project an image for each eye onto and back to their respective polarized lenses to produce a perspective correct stereoscopic image. Neat stuff.

  • Hi 🙋🏻‍♂️ trucker here. I see reflectors just fine

  • One time I almost hit a guy walking at night. He was wearing dark pants and a black hoodie with the hood up over his head. The only reason I could see him at all while he was crossing the dark non-lit street was the reflectors on his shoes. Guy doesn't even know his shoes may have saved his life. Also, don't j-walk at night if you're wearing all black in an area with no street lights, please! I don't want to ever hit a person, but if I can't see you at all then I don't know you're there.

  • This channel sucks at making people dumber.

  • 11:10 I felt that.

  • In Australia, we have retro-reflective road lines, they are quite effective. We also put red road markers on the left (the side we drive on) to mimic the back of a car and white on the right to mimic the headlights of other cars as a way of indicating the sides of a road

  • 3:21

  • epilepsy warning, flashing lights throughout

  • 13:34 and I bought two! **takes out disassembled cat**

  • Ohh :) cool kitty :) greetings from Poland :) cool video :)

  • I love how passionate he is about road safety things.

  • " This is a dog Sol "

  • Liked this video a bunch. great job! really informative!

  • No my favorite is what i've seen. Crossing signs with amber LED's flashing around them. Or stop signs outlined with red LED's. Yeah I know.

  • I'm gonna go out on a limb here and guess that this was made right around the time that the quarantine really started getting to you...

  • The best part starts at 3:30 - so unexpected

  • Surprised there was no mention of 3M's front projection material, as used in the original Superman movies.

  • I believe diatoms were also used in some street paint for how they can be similarly retro-reflective.

  • More cat please.

  • People on DRLs at night should be getting pulled over, even if they are taxis.

  • "This is a cat." Me: Immediately stops listening to Alec, and starts talking to the kitteh.

  • My guess about why we don't use retroreflective garage door sensors is that cars and other vehicles have retroreflectors on them. So a source signal and retroreflector set up could be fooled by a car parked in its path - not good. Whereas a signal and receiver setup wouldn't be fooled by a retroreflector in its path.

  • Did you say heidth?

  • The new signs that are really bright are flourcent diamond grid reflective sheeting from 3M I work in public works and make many of these signs and it's while it's really bright we have seen a reduction in accidents on the roads and collisions with the signs themselves so it seems to be doing its job

  • In an interesting note...according to an FBI video I saw, bullets do not bounce like light. Instead, if you shoot a wall that the bullet will bounce off, the flight changes to almost parallel to the wall.

  • Your videos are always informative in an interesting way. I really enjoy your not over-the-top sense of humor.

  • Anyone else get the feeling he is looking into your soul at 3:43

  • probably not used on garage door sensors because if something ELSE (say a car, or the retroreflector on a bicycle) was in the path of the beam, it might well reflect it back just as effectively, and fool the sensor into thinking the door was clear to close.

  • 17:52 solution - its a bad idea to drive along with your high beams on continuously. You're either driving too fast, or need to get your eyes checked.

  • 11:09 - 11:20 When and how to use headlights: ALWAYS. If you start the engine and put the car in gear, TURN YOUR FARKING HEADLIGHTS ON BEFORE THE CAR STARTS MOVING. Rain, shine, snow, sleet, hurricane, noon or midnight, on a highway or a back alley, out in BFE or in the middle of downtown --- TURN THEM ON.

  • FYI for anyone that doesn't already know, while highly visible signs using this principle are certainly important, the *primary* purpose of headlights, is so that OTHER drivers can see YOUR car. Which is one of the reasons why your headlights should be on ALL the time you are driving, even during the day. Sure, maybe in broad daylight other people with decent vision, that are paying attention, can see you just fine. But the older person who hasn't had their eyes checked recently? Or maybe the younger person that is chatting with friends or changing the station on the radio (or their iPod) will have just that much more chance of seeing you (and taking care not to veer into your path) if your headlights are ON.

  • Because I'm short and round I refuse to wear an orange vest. I look too much like a barrel at night.

  • That face you made in the mirror was creepy.

  • Damnit saw a Culvers sign in one clip now I want fried cheese curds

  • I have a projector screen setup that works in a similar manner. Makes watching movies, even with the lights on, totally long as your viewing angle is within about 20 degrees of the projector lens.

  • Hey, I have a "cat" too! Same color and everything!

  • 3:26 - OMG I'm dying here. Waking up my roommates rolling. It's too much... 19:14 - Can't use a retroreflector with a garage door opener because it can be fooled by a reflection caused by an obstruction: Let's say you are wearing retroreflective shoes... You'd be injured.

  • Sorry I can't hear you over the insects 🤣

  • I have retroreflective jacket and pants 😎

  • Could the hexagonal pattern on the reflector be to trick the brain into noticing it more? Like black and yellow stripes?

  • Regarding reflector patterns used for self driving; look at “April Tags”. They appear to serve a similar function. I use them to assist my matterport camera to better locate itself in a space.

  • I can tell you from big trucks the difference is marginal. At least in a fire engine ¯\_(ツ)_/¯

  • I've long thought speed limit signs should be programable, radio controllable from a central location with radar and camera. (Even as a professional driver.)

  • I also remember watch a documentary here on youtube about AI vehicles and they had those self driving semi trucks you were talking about, i cant for the life of me remember what it was called

  • Deflective you has great hair

  • that was a magnificent cat =)

  • Retro-reflectors are an array of half-cubes; three faces on each. Each face reverses the light's direction in one coordinate, working out to a 3D reversal of the light beam.