Neil deGrasse Tyson Explains LED Lights

What’s the difference between light and heat? On this explainer, Neil deGrasse Tyson and comic co-host Chuck Nice break down why some lights make heat and others don't.
Discover the science behind LED light bulbs. What is the difference between light and heat? We explore the light spectrum from infrared to UV. Should a light bulb be able to get hot? How do LED lights save so much energy compared to an incandescent bulb? We answer the question: Is red hot really that hot?
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Science meets pop culture on StarTalk! Astrophysicist & Hayden Planetarium director Neil deGrasse Tyson, his comic co-hosts, guest celebrities & scientists discuss astronomy, physics, and everything else about life in the universe. Keep Looking Up!
#StarTalk #NeildeGrasseTyson
0:00 - Introduction
0:18 - The difference between an Astrophysicist and a Photographer
0:38 - The science of infrared energy
2:45 - The wasted energy of traditional lightbulbs
4:09 - The brilliance of LEDs
9:10 - What are black-lights?
9:58 - Closing notes

[@StarTalk]

Have you been converted to LEDs or are you still faithful to the incandescent bulb?

[@19580822]

I use an old 100-watt incandescent bulb to heat my well house in the winter. Does a pretty good job. My granddaughter has an old Easy-Bake Oven with a bulb to heat the food. Works great! A fantastic heat source! Seriously though, I think more people would use LED bulbs if they were not so expensive. I myself still buy halogen bulbs when I can find them.

[@jordanbauer740]

probably not related to lightbulbs but just last year my monitor stopped working properly(the brightness of the screen was not working (you could see what was on the screen if you shined a bright light on it) so I got an led monitor instead.

[@tomhenderson2430]

I converted from 1950s fluorescent fixtures that weighed 40 pounds each to LED shop lights(same length) that weighed 2.4 pounds and cost $9 each over my whole business, like 20 fixtures. My light bill was over $300 at the time. It hasn't been over $110 since and it's more than twice as bright inside. CONVERTED

[@tomhenderson2430]

The savings alone paid for the purchase the second month I got the fixtures.

[@seektruth8662]

I was CONVERTED when I climbed my rickety ladder to the peak of my roof to change my spotlight to LED and knowing I wouldn't have to do it again for 10 years and that it would use 85% less power and put out way more light. If it were up to these progress haters we would all be living in caves and flipping over rocks to find dinner, "just like my Pappy used to do and his Pappy before him" Blehhh.

[@montrealplay]

Incredible coincidence: a few days ago I explained the same thing to my 14-year-old son. I showed him all the types of light bulbs and explained about lumens, watts, color spectrum. I explained to him what LED means ...

[@StarTalk]

Great minds think alike!

[@durragas4671]

Well done! I remember my dad used to explain LEDs to me.. that was before we had LED indoor lighting. It's so important to explain things to our kids.

[@SAJe_53]

Did you also explain candella?

[@xaxabdo]

My father didn't explain anything to me about LEDs, he just gave me a screwdriver and 10 of them to install in the living room...

[@SAJe_53]

@@xaxabdo And did you explain to him that you don't need a screwdriver to install a lightbulb, LED or otherwise?

[@patrickwalsh2361]

That was illuminating!

[@StarTalk]

Ha ha!

[@alecblack9205]

neil you’re such an inspiration and just wanna say i love these videos and all that you do!! and chuck always keeping things light and funny love you both

[@musicloverme3993]

"keeping things light" - I see what you did there!

[@beyond_the_tequila_rift3194]

Same feeling for both of these two wonderful human beings we've been gifted!! 🤝

[@NielvanSteenderen]

Absolutely genius having Chuck on the show! Watching you guys bounce off each other is just wonderful. Real synergy.

[@dawnhansen7886]

100% agree ❗

[@pauljames9596]

My gosh, the excitement I have from this understanding of knowledge based on pure objective facts is priceless...

[@StarTalk]

Knowledge is power!

[@christinet638]

same

[@sjoeee]

Nice explanation! A correction: blue LED was revolutionary because it allowed the use of phosphor coating to create full-spectrum white light, much like what fluorescent tubes do. Mixing RGB diodes does not really create white light of any good quality since RGB diodes generally have a very narrow spectrum of emission; therefore produce very poor color rendering. Also, LED:s do get hot due to inefficiencies. That's why higher wattage bulbs always come with heatsinks to dissipate the heat. They don't NEED to get hot to function like incandescent bulbs, but heat is a biproduct that has to be dealt with.

[@LiraeNoir]

Which is why higher end lights are not RGB but WRGB, with pure white light in there. It helps with color accuracy, and in other use it help with brightness (OLED TV for example have brightness issues, so they need a lot of pure white light on the panel to push brightness up)

[@martinda7446]

I was sitting in the service department waiting for blue LEDs and blue diode lasers for years. I understood the big leap they would allow. White LEDs are made with two techniques, that described by you and also that described by the big fella. Our eyes evolved with three light sensitive cells. Hence the fact RGB is seen as white light. It all happens in the brain. The bandwidth of light from an LED fairly closely matches the sensitivity of the cells in our eyes. An extremely wide gamut can be obtained this way. Leds are becoming more efficient and even at their worst are an order of magnitude better than any incandescent lamp. Heat and noise, electrical and radiated go hand in hand with all electronic devices.

[@skylark8828]

@@LiraeNoir I don't know if that's true for all OLED TV's, they had advantages over LCD type TV's (apart from absolute contrast in the high-end ones) as there was no backlight needed, black and dark parts of the image on the OLED TV's looked so real against the vibrant colors (back in 2018). I still have mine.

[@StarTalk]

Thank you for your knowledge!

[@sjoeee]

@@LiraeNoir This conflates display technology with general purpose lighting. Indeed, on a display you only need the three base colors, since the ratios of light are controlled directly by the display, and are viewed directly by your eyes. As you say, a white diode is used sometimes to add brightness. For general purpose lighting RGB does not work, since the light now has to interact with the world before it hits your eyes. This means the ratios won't be correct unless you start out with a full-spectrum white light.

[@dickbower7907]

Most "white" LEDs are Ultraviolet with a fluorescent material...much like fluorescent bulbs. Single LED not RGB.

[@STONEDay]

UV diodes are VERY expensive because they need to be encased in metal & glass. UV breaks down plastic. UV diodes on my grow lights are all encased in metal & glass.

[@LaMirah]

This is true. Trichromatic "white" light is quite odd, since objects don't know about human vision and won't reflect the very specific frequencies of electromagnetic radiation as if they were reflecting true, multispectral white light. Proper white LEDs shine blue/violet/UV light through a mix of fluorescent substances to "fill out" the spectrum so stuff around you can reflect enough frequencies that your eyes won't be able to tell the difference.

[@paulhill4843]

​@@STONEDay Yeah, they ain't expensive nowadays. A 600W Horticultural LED lamp costs about 200USD to make - if using the best LEDs and Driver on the market. It's the 275nm LEDs that are still quite expensive - but you don't use them in horti.

[@scy1038]

Neil Tyson is explaining this topic right now. I promise you aren't as knowledgeable as him, quit trying to prove your intellect.

[@booqueefious2230]

Is Chuck forgetting about CFL? Because that's what we were "transitioning to" not LEDs at the time, they were still really expensive. And the CFL lights they were pushing caused all kinds of problems. Now LED light bulbs make sense. And you can still get regular light bulbs, they're just marketed differently because they still have valid uses.

[@LiraeNoir]

As a 40+ years French, nope we measured in Watt. Lumen was at some point on the packaging, in small print, but colloquially like in the US we always thought and spoke in Watts. And nowadays still in LED bulbs we have big "incandescent Watt equivalent" numbers on the packaging to help people select their bulb fast.

[@willinwoods]

Same as in Sweden.

[@OvyWanKenobi]

Same in Romania. Many here were against switching to LED because the LED lights were not "powerful" enough. "I use a 15W incandescent bulb in the bedside lamp and you want me to replace the 100W bulb with a 10W LED? It won't be able to light the entire room".

[@LeKrutes]

Same in the Netherlands

[@softerliving]

Not only do LED lightbulbs use less energy, you can still put them in all the old lamps. People who find problems with LED want to have problems. Don't know where I was, but I'm glad I missed the controversy.

[@brainstewX]

6:10 As I recall, people were losing their minds because we were being steered toward the CFLs (the mercury bulbs), not the LEDs.

[@sirspark-a-lot8782]

Correct

[@erucolindo8611]

CFLs were almost intentionally designed to be an intermediary technology between incandescent and LED. When EISA was signed LEDs were still prohibitively expensive, over $20 for a quality lamp. CFLs were the compromise of energy savings vs cost for consumers until the technology developed to create affordable LEDs

[@theedavierg4581]

as someone who has watched your videos for years and also currently starting my electrician apprenticeship. This is perfect. Thanks Neil and Chuck. We constantly convert houses and light fixtures from incandescent to led. And we often talk about how new wire will probably be made for these led lights because running your normal 12-2 romex with 120 volts is just overkill for power and price.

[@Soapy-chan_old]

In germany normal light bulbs are illegal (for like 15 years I think). Correction: Illegal or not available to buy in normal lamps and stuff, but some things still require those which can't be replaced by LED. LEDs are awesome. When I first learned about them I was fascinated.

[@gummsingi8591]

Now I want back my incandessssent light bulb in my lamp by my bed for reading my book. Warm glow.

[@davideric7519]

It’s brand new to me Been using them old American Edison’s for decades and hard to change

[@SeanBZA]

Funny thing is here most of the switch over was done by simply increasing the customs tariff on incandescent lamps to a higher value based on efficiency, so the common incandescent lamp increased in price to more than the CFL lamp, and the halogen went up in price as well, but not as much, as they were more efficient. You still but incandescent lamps, as they are still made for certain applications, like for hot use in ovens, and for rough service use. Even in Germany you will still see bulbs available for this use, as no LED can replace them.

[@davideric7519]

@@SeanBZA As long as I can get me guns 💪

[@Soapy-chan_old]

@@SeanBZA Yeah true, I wasn't aware of that nuance. Thanks for the correction :)

[@augustinesim1672]

08:20 "it blue over the entire lightning industry" you missed a good pun!

[@GeorgeBP81]

This braught back memories! In the 90's in Romania, we switched the electric stove to a gas stove and the electrical company audited us because the power bill went down by half. It happened again when we changed 800 w incandescent light to aabout 100w fluorescent. The change was so dramatic that they taught we were stealing electricity!

[@sandal_thong8631]

I can hear Neil's laughter in my head as I read this.

[@DoFoT9]

I like your videos before I even begin watching them, because I know they are going to be invaluable towards my search for learning and knowledge.

[@MaryAnnNytowl]

Yep, I do the same!

[@steven_porter]

Great video as always and thanks for clearing up the color temperature issue! As a video studio owner who regularly works with high power LED fixtures, I can confirm that LED's definitely get very hot. Active cooling systems for video lights are often significantly larger than the actual LED module and power supply combined. That said, they are substantially cooler than incandescent fixtures, don't throw as much heat via infrared toward the talent, and are much more economical to run.

[@bryandraughn9830]

Beat me to it!

[@bryandraughn9830]

Beat me to it!

[@opawel1]

I’m not an expert at all, but I think that most of the heat generated by LEDs is generated within a device and is not directly related to light emission

[@steven_porter]

@@opawel1From what I understand, it's a combination of the LEDs and the power supply circuitry that make the most heat. However in professional video, power supplies are often separate boxes that have much smaller (if any) cooling while the LED's themselves have huge heat sinks and at least 1 fan. I'm not sure how much circuitry is in the LED fixture vs the power supply module though.

[@47f0]

@@opawel1 - LEDs have a measurable resistance. In a circuit, if you have resistance, you will have heat. If you buy bulk leds, most of them over one watt are heat-sinkable - LEDs do produce heat, the ratio of heat to visible light is just vastly superior to that of incandescent lighting.

[@AuxFiles]

Always easy to learn from the information given. One of the greatest educators out there.

[@davideric7519]

I had zero clue on wtf an led was I was curious but no idea

[@djgene5621]

As a DJ, I use led dance lights. I used to use lights with 300 watt halogen bulbs. They were EXTREMELY hot, used TONS of energy (which often blew circuit breakers, fuses, or relay packs), didn't last long, often weren't dimmable, and if you touched them with your bare skin without wiping them clean they would blow as soon as they powered up. Now, led lights have a 10,000+ hour life, 25 watt leds are just as bright as the 300 watt bulbs, fully dimmable (even strobe), and they put off very little heat. They now are available in red, green, blue, white, amber, and UV, and likely more.

[@sirvapalot]

I was very quick to transition to LED lights throughout my home, being a disability pensioner, i realised 3watts was obviously cheaper to run than 60-100 watt old school light bulbs, and yes i run an LED TV and 5star devices like washing machine, my electric ⚡️ bill is usually about 1$150-$170 every three months, Queensland Housing wont provide Solar power, so running low wattage appliances is essential.

[@DragonX2X7]

Aus? England? Cause in QLD, Aus, homeowner can have Solar on their roof and the Gov will subsidies a part of the cost. Any excess will be sold back to the grid.

[@StarTalk]

Light Hack!

[@SeanBZA]

Yes that was the impetus long ago to move away from incandescent in most places. However they are still in use in areas where the lights are almost never turned on, like in substations, where the light might be needed once every 20 years, and no LED or CFL lamp is warranted to last that long, and not fail on turn on. Incandescent lamp can sit 50 years off, and work on power application.

[@iamsnipez8266]

I love these videos! You are such an inspiration to me Neil!

[@williamburke1882]

Ok so Chuck is not only hilarious but pretty much spot on. I know someone that bought a gross of old light bulbs before they were all taken away. Some were thrown away eventually but that's a whole other rabbit hole. And as always, Thank You Science!

[@stevemcstevens]

Some people bought them because the original LED bulbs sucked. They took about 10 minutes to get bright, whereas now its pretty much instant

[@davideric7519]

I love how Chuck is so spontaneous funny . His timing is impeccable also

[@LukeSumIpsePatremTe]

I live in cold place and the old lamps did produce a lot of heat. It's not just wasted energy, but energy that can be used to keep you warm.

[@MrT------5743]

@@LukeSumIpsePatremTe What about in the summer time in the deep south? You are heating an already too hot house that you now need more energy to cool it. How about using a heater to heat and LED's to light.

[@47f0]

@@LukeSumIpsePatremTe - and for many people who need air conditioning, the ratio is about 1 watt of waste heat for 2.75 to 3 watts of a parasitic air conditioning load. Incandescent light bulbs are a lousy way to heat your home.

[@TheRabbitRonin]

Who else with astigmatism hate led headlights at night?

[@bonsai_wolverine]

It is becoming unbearable to drive at night (and during the daytime with DRLs, for that matter), and the lights keep getting brighter, whiter, and more glaring. There's no need for LED headlights to be so bright and so blue-shifted.

[@peppeddu]

In some cases traditional light bulbs are still the best choice. In cold climates, LED traffic lights often get covered with snow. With traditional light bulbs this problem doesn't happen because the heat from the bulbs melts the snow.

[@roblena7977]

Actually it was the CFL that everyone was really getting pissy over. In their defense it is kind of bad but we got a much better alternative. From what I understand led has been around a while but was too difficult to mass produce the diods.

[@AceSpadeThePikachu]

I've always been curious how LEDs work on the physics/quantum scale. Incandescents are simple in that it's just black-body radiation, the same thing that makes stars, fire and stove-tops glow. Florescent and Neon lights take advantage of the quantum effects of electron energy levels in atoms by knowing that if you give an electron in a certain kind of atom a certain amount of energy it will temporarily leap up into a higher energy shell and then drop back down at a very predictable rate and emit a photon of light in a known wavelength. LEDs only became mainstream after I graduated school so I never learned about the science of how they work. Maybe this is beyond the scope of this show but I'd love to learn more.

[@SeanBZA]

LED's act in exactly the same way, though there they have a crystal that is doped so that there is a channel that has very constrained energy bands. Apply electric current and it will tunnel through if it has enough energy, ad in going through it will lose energy by emitting photons, which, by the doping are only in a certain narrow range of energies, thus colours. The trick with LED lamps is that you have a sourcve of blue or near UV light in a small spot, and on top of this you place a blob of mixed flourescent powder, made from a mix of rare earth oxides, that accept the blue or near UV light, and then emit photons of lower energy, thus making a blend of the original blue, or actual blue if it is UV, and then others add various amounts of green, yellow and red light to the overall light emitted, making it look to the eye like it is some light close to white. The original Nobel prize was making a LED out of silicon carbide, which has a high bandgap, and thus blue light, and later on making this also occur in regular silicon as well, thus allowing the existing industry to make the blue LED. More then came with making it more efficient, as the first ones were well under 1% efficient, but did make blue. Now you get LED's that are over 50% efficient at converting electrical energy to light, though still more than half your input power is going to be dissipated as heat. ps LED's are also able to convert light back into electricity, just have to apply light with shorter wavelength than what the LED emits and you get a voltage out, though efficiency is pretty much terrible there.

[@AceSpadeThePikachu]

@@SeanBZA Ah, so it's like how Neon lights work except the current is run through a solid instead of a gas, kind of like a ruby crystal laser or a quarts screen. Interesting. Though thanks to the second law of thermodynamics no device can be 100% energy efficient because any current in any conductor will encounter friction and thus lose heat, even in superconductors, and any photon will have to make it through the material the emitter is made of and whatever over covering the bulb is in before it gets to your eye, and some of those photons will be absorbed because no material is 100% transparent to any wavelength of light. Entropy always wins, no matter how hard we try to slow it down. That's why even though LEDs don't get hot (unless they're poorly made), they do get a little bit warm.

[@justrosy5]

Same!

[@cantordavid613]

Modern LED lamps don't require a combination of red, green, and blue diodes. LEDs these days incorporate a chemical substrate which, when energized by electrical current, radiates a particular wavelength of light. Some emit "warm" (yellowish) light, others emit "cooler" (blu-ish) light, but they don't use red, green, and blue diodes to accomplish this. We've come quite a long way since those days! :) There are customisable LED lighting assemblies which do, in fact, incorporate red, green, and blue diodes, but those are for user-customisable colour schemes, and they *can* produce white light, as well (but that's not their forte).

[@michaelsilver2636]

Loved the discussion on LED lighting. As an Electrical Engineer in California we have to use LED. But mainly because of the innate ability to dim LED without special devices necessary when we switched from incandescent to fluorescent. I think a more lengthy discussion of the progress of commercial lighting, including the long interim period of fluorescent lights (and how they worked) to LED. And what is high intensity discharge lighting (metal halide, high pressure sodium, and monochromatic low pressure sodium (note: LPS required near observatories because a single color wavelength is easier to block out by the large telescopes -think the city of Poway, CA). You can spend multiple sessions discussing man made light over the years.

[@hughleyton693]

You can buy dimmable LED light bulbs these days.. . . Personally in light fittings with 5 lights, I use two switches, one switches 2 LED's On, the other switch switches 3 LED's On so I have 3 levels of lighting, works very well.

[@lorassorkin]

Thank you for explaining that!! Could never understand that LED conversion before now.

[@ChrisHolzer]

4:10 fun fact. when streetlights here in Austria were first changed to LED, we had icicleshanging from them because the waste heat from the old bulbs also "defrosted" the light and so prevented the rather dangerous icicles to form. Now heating elements are installed in led street lamps to fix that.

[@galens2543]

So it was only “waste heat” in the summer.

[@joelwoodardart1829]

Thank you so much for this info. This will help me with my Warm/Cool contrast lecture for my Color Theory class this Friday!!

[@mobiledetail4you]

You two make such an amazing team, can’t get enough.

[@DanielBohnen]

Because I'm a science nerd and also work in lighting I constantly try to explain the LEDs are not dangerous in fact they emit less radiation then an incandescent

[@StarTalk]

Thank you for advocating on behalf of LEDs!

[@davideric7519]

I still like my incandescent as a god gun loving American

[@AbstractionIncarnate]

@@davideric7519 You hide. You are counterfeit. Stay away.

[@damyr]

@@davideric7519 exactly. God gave us incandescent light bulbs to feel warm and comfy. LEDs are a devil's work.

[@MrT------5743]

Who thinks LED lights are dangerous where you have to CONSTANTLY explain it to people? Maybe you hang around the wrong crowd?

[@Life_42]

Love your collaborations!

[@evangraham4607]

"A college education?" DAMN, Chuck! Came out swinging today.

[@traviscalvin431]

The thing that my grandfather always harped on with incandescent light bulbs was that in warm months when you might be running the air conditioner that 100W light bulb was actually resulting in a lot more power usage because the air conditioner then has to use electricity to cool the air back down.

[@NPazdernik]

I love the Black Lantern shirt Chuck!

[@joeblow9891]

why the sound level is always so low...? anyway I like the content

[@Khal_Maharani]

Beautiful topic you guys bring up! Thank you!

[@DG360]

As a lighting designer and member of the ALA, I really enjoyed this talk. When talking about temperature and color we always measure color by Kelvin. Kelvin is the temperature associated with the colors you speak of :) Wattage or the amount of energy used to create the light we see from multiple types of lamps has over the century been confused with the amount of light people normally got with incandescent. Lumens or the measurement of light from a lamps source vs wattage has continually been the subject of discussion since the 90s and watching the evolution of lighting has been absolutely fascinating. I'd love to talk about the hoax the industry pulled on the public with "daylight" bulbs in the 7k purple spectrum lol Daylight is actually more towards the 2800 to 3200 Kelvin spectrum of color because it is the color of our sun which is why a lot of people still gravitate towards incandescent ;)

[@hughleyton693]

No, Daylight covers all the range from about 2700 to over 7000K

[@skipodap1]

These are great videos, thanks much for making them!

[@majdaldienshreiky8340]

Just perfect. I needed this.

[@7thassasin]

Love this show. Always mind blown. This is legit Post Doc learning.

[@radiotec76]

Glad this was finally straightened out. Chuck Nice had it right. It’s amazing that my co workers actually believed that the Bureau of Alcohol, Tobacco and Fire Arms was storming peoples homes to seize their incandescent light bulbs.

[@craigmcmahan9600]

Great topic. I always wondered why the LED was so popular now when my first science kit had LEDs. It was the magic blue....

[@knight-mares]

Thank you, Science.

[@Onio_Saiyan]

LED lights are cool.

[@anthonyarmstrong1460]

Thanks a lot guys. Enjoying this video very much.

[@1953bassman]

We used to use colored incandescent 75 watt flood lights that would get very hot if they were lit for even just a short time. Now there are LED floodlights that produce the same amount of light and in the same colors that don't get hot at all. They can be handled immediately after being on. One of the benefits of using more efficient lighting is that fewer new power plants need to be built, saving money and reducing pollution.

[@lo-firobotboy7112]

Question: What is actually generating the light we see emitted from the diode? I understand that there is a gap that the electricity must cross but I still don't understand the mechanism that converts that energy to visible light. (Thankfully, we moved pretty quickly through the compact fluorescent era. Those are terrible. )

[@victorcapel2755]

simply put (because I don't know the advanced answear) it's a flat piece of two or more materials that when put under current, transmits a particle between eachother and emitts a photon in the process. But I could be wrong here, someone I'm sure will correct me if I'm wrong.

[@connorV96]

So as Neil said, the LED emits a FREQUENCY which our eyes can detect, rather than heating a coil with electricity to make it glow hot. The Diode simply emits the specific frequency for 'Blue', 'Red', etc. 😀

[@thelongdaysofwheeling124]

@@connorV96 But how??? A coil gets hot and tosses off heat and visible light. What causes the LED to give off visible light?

[@connorV96]

@@thelongdaysofwheeling124 Unfortunately it's hard to explain further without a knowledge of semiconductors, but basically the positive and negative electrons that flow through the semiconductor produces energy in the form of photons. It's known as "Electroluminescence". The type of semiconductor will affect the frequency emitted, which dictates if it is a 'Blue' Semiconductor etc.

[@thelongdaysofwheeling124]

@@connorV96 that makes more sense, thank you.

[@Movie16Master]

The one thing bad about LEDs is with photography. I watched a whole video breaking down the science of it, but because it's made up of Red Green Blue it doesn't bounce colors back to the camera properly. There are some crazy expensive LEDs that do a pretty good job fixing this issue, but generally speaking LEDs tend to struggle in that aspect.

[@klausm5460]

Many Europeans also stockpiled on conventional lightbulbs when they were phased out step by step by the EU. My impression is that people are more interested in the design opportunities provided by LEDs than in the energy efficiency.

[@SarcastSempervirens]

I love Chucks jokes, they're always from a completely his point of view, never cliches, but at the same time benign and almost geeky. Great duo!

[@moomoochacoo]

I'm literally in a Cinematography class, Physics of Light class (no math thank god), and a Lightening class (all classes for art and film) and this helps out a bunch. Gonna share it with my class.

[@AnyFishKiller]

It’s true that the invention of the blue diode changed the game but not just because you can now combine RGB. Most indoor lighting is actually a singular diode emitting white light. But the way it works is it’s actually a blue diode with a phosphor coating. The phosphor coating spreads some of the blue light into different spectra creating what you see as white light. Fun fact, most of the blue photons from the white diodes is unaltered, passing right through the phosphor coating.

[@BState]

To the people who commented about LEDs getting hot, what Neil meant is that LEDs do not EMIT infrared thermal radiation like old incandescent bulbs did, they only produce some heat (relative to the diode's actual wattage draw) under the LED's chip where the heatsink is, they don't emit it from the diode as radiation but only conductively. Without the heatsink it wouldn't live for a long time.

[@RobertoFischer]

Could have mentioned the color rendering index, which still kinda sucks on regular LEDs, but doesn't on incandescent, which is why some stuff looks weird under LED lights.

[@harvey66616]

Depends on the LED bulb. Modern LED bulbs have good CRI, in many cases _better_ than a tungsten incandescent.

[@clysen8234]

This is an amazing channel. Both of you are awesome!

[@shomz]

6:09 Chuck explains why Murica can't be forced to use LED lights

[@travismack3994]

Tyson has done a fantastic and much needed job of promoting scientific literacy and appreciation in the all too anti-scientific US. And I admit I don't know how old this installment of StarTalk is, but I assume it postdates the introduction of LED light bulbs for standard household lighting. If my assumption is correct then, the last part of Tyson's description of today's white LED workings is not correct. While it's true that the first "white" LED lamps were a red-green-blue combination, they were a relatively weak and not a very good white light source. On the other hand, todays white LED lamps are something entirely different. In fact they are more akin to those familiar fluorescent tubes that have been around for many decades - in this way: Those fluorescent tubes all emit UV light; they're all "black lights", but the fluorescent coating on the inside of the glass absorbs the UV and re-emits it as white light. Todays bright, efficient LED lamps, like all the ones in your home, are really UV LEDs with a special coating that fluoresces white. Even Neil Tyson ain't always right.

[@harvey66616]

_"Even Neil Tyson ain't always right"_ -- indeed, I've seen in these videos that outside his actual area of expertise, he is nearly as likely to be misinformed as the rest of us. As a scientist, I'll bet he's more readily able to update his understanding when confronted about it, but he does get things wrong plenty in these videos.

[@jamiboothe]

Strangely, astrophotographers are not fond of outdoor LED lighting, because it is broad spectrum. So, it is much more difficult to filter out the light pollution, using specific frequency filters.

[@arnhelmkrausson8445]

Two minor corrections: In Europe ( Germany in this case) we still use the metric of incandescent wattage. There's even the conversion printed on the packaging of LED bulbs. As in "this LED is the equivalent of a 60w incandescent bulb". Heat is very much an issue with LED, but the heat is not dissipated in the direction of emitted light. It actually comes out through the backside of the wafer and so called "high power LED" need an appropriate heat sink. That's the reason why some LED bulbs have a metal casing that gets relatively hot, although temperature is not generating the light, it's a byproduct in the same way that the CPU of a computer needs a heat sink.

[@jeffs6090]

Plus, multicolor led lights are cool. They can be controlled by an app on your phone. I've replaced most my home's lighting with these.

[@AssemblerGuy]

Small correction: At first, they tried making white light by combining red, green and blue LEDs - after all, that's how TVs, computer and phone screens make white light. However, this kind of "white" light is good at illuminating red, green and blue objects, but all the other colors would appear dull and a bit "off". The RGB-mixed light has a poor color rendition, so they soon switched to another way of making white LED lights: Start with a (deep) blue-violet-ish LED, and smear some goop (that's the light orange or yellow stuff you sometimes see in LED light sources when they're turned off) on top of it, which will do the phosphorescence that Neil explained at 9:10 : Use the right kind of goop, and it'll add all the other colors to the blue/violet from the LED, and you get lights with a color rendition that leaves the old inefficient incandescent bulbs little to wish for. I hope "President Blacula" is taking notes here 😉

[@lindavaughan6187]

Congrats on the book !

[@AndreSantos-kk3en]

I love you guys! Often I play twice your videos!

[@johneonas6628]

Thank you for your video.

[@miltonayala3845]

LOVE YOU NIEL, You're my hero. My brother met you, he rubs it in all the time. However, LEDs do get hot, not as hot as Edison or fluorescent bulbs. The heat of a single LED can be dismissed, but when you add more diodes (increase the packing density) for a given area (DIP, SMD, and COB) the heat factor can not be ignored. Those densely pack LED arrays require heat sinks or fans. Example LED floodlights, LED car lights and any COB LED in general. As the wattage or luminosity increases, so does heat. Some home LED bulbs, have a heat sink base.

[@ehar7058]

It doesn’t hurt to limit your blue-light (UV) exposure right before bed though, red incandescent light might still have some uses after all…

[@mariogastelum1463]

Very ENLIGHTENING !!!!

[@RJOVenturesInc]

Very informative! Now I know! Thank you for sharing. 🙂👍🏾 #ThankYouScience

[@vcoolpool]

LED = light emitting diode. Semiconductor diode which glows when voltage is applied. This should have been stated before the explainer began. Also Physical Science 101. Thanks again guys for yet another video.

[@Kindrick]

I remember, for the longest time, anything that used LEDs only used red and green, so anything with LED indicators or LED decorations only gave off 3 colors: red, yellow, and green, because you can mix the red and green to make yellow. For most indication purposes, that was enough. Like, for a battery indicator: green, you're good; yellow, a little low; red, will gotta recharge soon. And I used to have a frisbee that had a couple of LEDs on it, one on each side, one was red and the other was green. When you threw it, it'd make either a red and green ring around it or a yellow ring, depending on how fast it spun. I don't think I ever saw any blue LEDs until high school, but they were still rare, but it was also around that time that we started to see these expensive LED TVs.

[@ailivac]

And now that we have blue LEDs, designers think green and red aren't cool enough anymore, so every indicator has to be obnoxiously bright blue or white.

[@mikestevens1441]

Great work guys!

[@marystephens765]

You two guys are great! 🎈🎈🎈

[@James-pl2oy]

Thank you Shuji Nakamura for revolutionizing the lighting industry

[@damianmlamb]

How is this only 1.68 million subs??? This is gold!

[@Amalgamotion]

I'd like to add to chuck's imitation of 'how dare you' the theater lighting department I worked around at the time hissed like cats at the led lights we started putting in. Told us we couldn't change any of the lights inside the theaters. (our complex spans acres) Even though it was literally keeping the doors ope longer by how much we were saving in energy costs... You guys are awesome!

[@LauraIon1961]

I love these explainers. Thank you! P.S. If physics would be taught like this, kids would be more into STEM.

[@lunarthief6501]

I do really enjoy that warm tungsten glow. I wish I could get a little closer to the color with less. Thank you science for allow me to be more efficient.

[@willinwoods]

The high end audio amplifiers from Krell had blue LED on/off indicators early on, when those blue LEDs had only just become available, and cost magnitudes more than LEDs of other colour. Of course, when the amplifier itself cost $10k+, relatively seen, it wasn't that much of an extravagance....

[@frankwilson7666]

I used to work for a company in New York that manufactured LED lighting. Everything Dr. Tyson said is true. In my testing, White light degrades faster than most other colors. Red light is the best I have never seen it lose lumens,

[@Belznis]

In Europe they had Lumens, I think it was the case at least, because the first LEDs were not bright enough. They were expensive at first. Now almost everyone uses them and they are cheaper and often brighter. A lot of people used to complain LEDs have no warmth.

[@MaryAnnNytowl]

I so enjoy learning things from you! Well, I enjoy learning, period, so I may be bit prejudiced. 😄 But that's how I keep my mind agile!

[@shamsandharia123]

Wish you could be more open about alien life forms in our universe

[@jpteknoman]

there was a transition period here in EU with the newer light bulbs' boxes having a reference to what kind of old wattage bulbs they were comparable to but that has been phased out... and there are no incandescent light bulbs to be found anywhere anymore. my grandma's house has 1 that hasn't burned out yet but when it does, it will be the last such bulb we ever get to see. maybe we'll put it in a box for safe keeping as a relic of a bygone era. it could become a valuable antique at some point who knows

[@danvanf]

If LED's don't get hot, why do so many of them have heat sinks? I have had A60 LED's that generated enough heat to burn if touched near the base. Very clearly they do not have as much heat loss as any other affordable light source. It is however concentrated near the semiconductors driving the LED. That heat is often dissipated by the case.

[@1967urban]

Mr. Neil & Mr. Chuck. Thank you so much for your outstanding contribution to understanding how the world works. I am happy to look at all the posts, even if I am familiar with the topic. There is always something interesting and new to be found. In this video, however, I think you made a mistake. We all know (hopefully) what you wanted to emphasize, but @ 1:55 you say, "You can touch it and feel the temperature." As far as I know, we can’t feel the temperature, but we can feel the heat. At least that's how I learned in your "explainer" about temperature and heat. :) My comment is not a critique of your work. Just enough to know that you (at least some) are paying attention.

[@AustrianCitizen]

Great one 👍

[@infotechnorte]

Amazing video! Could anyone help me with a question? So, working with LEDs I noticed that the blue LED uses more power than the others and the red ones require much less. Is it related to the wavelength/frequency of each color or something?

[@chancemeyers8502]

I love how Chuck is wearing a Black Latern shirt while talking about light spectrums lmao

[@logix8969]

I always love UV lights. Though I hear you shouldn't look directly at them for long because it's bad for your health/eyesight, when you do look at the,, they look very fuzzy. You can actually "see" (or not) the transition from visible light to ultra-violet light. Fascinating topic. Although I knew about how LEDs and light blending work, I hadn't considered that the shift from red to white to blue hot was a result of a rise in the emitted wavelengths of the EM spectrum, and that beneath red was infra-red, hence IR cameras. If you're curious, when programming graphics, RGB light takes up 3 bytes (24 bits) of memory. Each byte (one for each channel (i.e colour)) has a value range of 0-255 (inclusive), giving a possible range of ~16,777,215 different colours (that's 16 MILLION, with an 'M'!). Of course you don't see all those colours, monitors have different ranges which they can display, depending on the hardware and the pixels themselves, but it's amazing that we can represent so many colours with only 24 1's or 0's.

[@scottmcintosh4397]

💡 A most illuminating subject 😶 🌌🔭

[@leonardtramiel8704]

Small correction. The video said, incorrectly, that phosphorescence made things glow in black light . Black light causes things to glow because of fluorescence.

[@JohnFleshman]

Another great Splainer. I Love led light bulbs in my house. Now led headlights are another problem all together.

[@robertcampomizzi7988]

You helped me tonight..I just remembered when he taught me about phosphorescense. I didn't believe him at first, cause , well it is still fascinating. Dad was a chemical engineer. He has a brain tumor now. I can't talk to him about practically anything anymore. Watching you guys and people of your ilk helps me remember just how awesome scientists and science are/is. Thank you for helping me recall fond memeories!! ❤

[@lxathu]

Even in Europe we've been learning the lumen values and still rely on the old Watt equivalents when it's detailed. Before LED lighting, hardly anybody without the relevant education had heard about lumen - Watt was mostly impossible not to hear about (even if its real meaning was/is unknown).

[@donthompson2188]

This is the first time I take exception to something Neil Degrasse Tyson has said. The idea that incandescent light bulbs are very inefficient. Yes, it is true if your perspective is narrow BUT in my house that bulb is heating my home so my furnace is heating less. So for 9 months out of the year that bulb is nearly 100% efficient. In the summer months lights don’t have to turn on until 9 or 10 in the evening and only run a couple hours. It’s true an outdoor light is wasting all of the heat energy but indoors, not so much. My problem with LED or compact fluorescent bulbs is that the electronic components are not robust enough to last as long as the LED’s themselves causing premature failure. In my experience lasting only a little longer than an incandescent bulb and costing 10 times more. I appreciate the science, I only wish LED products were up to the promise.

[@47f0]

Doctor Tyson's next video should be about time travel, because clearly you are posting from the 90s. If you use cooling in your house ever, at all, one Watt of waste heat also brings along about 2.75 to 3 Watts of air conditioning load. If you're using heating it's still a rather inefficient way to heat - dedicated heaters do a better job more efficiently then incandescent light bulbs. In our three bedroom house, complete with porch lights, yard lights and garage lights, I was constantly dragging out the step ladder to replace burnt out incandescent bulbs. I think I have replaced one, possibly two LED over the past 12 years that we've lived here since I replaced all of the bulbs with LEDs. You need to stop getting your science information from Trump rallies.

[@harvey66616]

_"in my house that bulb is heating my home so my furnace is heating less"_ -- The best you're going to get from a light bulb is 100% efficiency in terms of converting excess electrical energy to heat. But modern heat pumps can achieve conversion ratios of 2 or 3 to 1. They are just moving the heat, instead of getting it from the electricity, so they use a lot less electricity for the same amount of heat produced. Granted, lots of places still haven't moved to heat pumps for heat. And in these cases, incandescent bulbs aren't completely terrible. But most places don't have a 12-month heating season, and so even in those places that don't have heat pumps, the extra heat from the incandescent bulb is going to be a problem at least some of the time. _"I only wish LED products were up to the promise"_ -- my home is almost entirely lit by LED (just a few bulbs that are halogen and for which no suitable LED alternative is available), and I don't miss incandescent _at all_. Modern LED bulbs don't involve any serious compromises at all.

[@greentau]

Neil & Chuck you forgot to talk about the part where Astrophysicists and Photographers disagree on the terms "warmer" and "cooler"