World’s Lightest Solid!

This is aerogel.
The world’s lightest, that is least dense, solid. This piece has a mass of just 1.22 grams. That is only a few times the mass of the same volume of air, which kind of makes sense because it is 99.8% air. In fact, some aerogels are so light that if you removed all the air from them, they would be less dense than air. I have long been fascinated by aerogel so I actually flew out to Aerogel Technologies in Boston to find out why was aerogel invented. How is it made? Why is it such a good thermal insulator and what is it used for? – Okay, we are going to try an experiment to demonstrate the insulating power of aerogel so over here we have two setups: one with a glass petri dish, and the other one with aerogel on top. – Both are made of silica, but with very different physical structures. We’re gonna see how long it takes to melt these chocolate bunnies with a Bunsen burner. – Now to have a look at this experiment, we have a FLIR T1020 which can see temperatures up to 2,000 degrees Celsius. – Looks like it’s getting pretty hot. – Yeah, you can see that the glass is getting really hot already. And after just a minute: – It’s starting to smoke.
– Okay. – It’s definitely melting and smoking. Oh, yeah, here we go. I would say that’s phase change. – We’ve got a liquid chocolate situation. We have some smoking bunny. Over here, the bunny is actually sort of melting over, and look, there, it’s sort of tilting to the side. – Alright, I think we’re going to call that a melt. – What is that?
– Oh! On cue, on cue. [Laughs.] – I would say that is material fail. – Not only did the bunny melt quickly, the petri dish cracked under the thermal expansion. – Wanna pop it in? – So now let’s try the aerogel. [Music]
– So how is aerogel invented back in? – Back in 1931, a guy named Professor Samuel Kistler had a bet with his colleague Charles Learned. – Now the bet revolved around jellies,
like peanut-butter-and-jelly jellies. Now the thing about jellies is they are actually a combination of liquids and solids. [Music] I mean, they’re mostly liquid,
but it’s embedded within this 3D solid structure. – So if you think of a gel, like jello, has a skeleton with nano-sized pores that gives it its rigidity, and then that’s about 1% of the gel. – So the bet was this: Could you remove the liquid from the jelly? Without affecting the solid structure?
I mean, if you just evaporate the liquid out, well, then the solid structure shrinks, because as you remove liquid molecules, they pull on each other, and they pull on the solid structure around them, basically crumpling it from the inside. Now Samuel Kistler solved this problem in two ways. First, he realized you could replace one liquid with another inside the jelly just by washing it thoroughly. So you could swap out, say, water, for alcohol. And then, if you take the jelly and put it in a high-pressure vessel called a autoclave, – By heating it to the high-temperature, high-pressure point called the critical point of the liquid, that liquid transformed into a semi-liquid, semi-gas called a supercritical fluid. – At this point, there is no longer a distinction between liquid and gas. Those molecules are no longer pulling on each other. – So once you’ve depressurized the vessel, that solid skeleton, that 1% of the mass of the gel, is left behind intact, except for where there was liquid in the pores before is now gas, and that solid skeleton, that nanoporous solid is what we call aerogel. – Kistler published his findings in Nature in 1931. It is getting pretty hot as you can see through the thermal camera. But coming up on three minutes, there’s still no sign of melted chocolate. So we’re gonna pull out a thermocouple and just check the temperature underneath the bunny. Like, underneath the aerogel, and see what, what the flame temperature is. You can kind of see that, that parts of the bunny are getting hot, but it’s not the bottom of the bunny, It’s all the, around the bunny. – Exactly. That convective heat is moving up and around the aerogel, – So you can see the thing is getting red hot.
– And by four minutes, the bunny is looking a little soft. – Still pretty good though, considering how easy it is to melt chocolate. – Can I put my finger here? – Be careful. It’s not that it’s hot, it’s that it’s brittle.
– Right. – But yeah, totally cool to touch, right?
– It is, it is just warm to the touch. – He made aerogels out of all sorts of things. He made them out of eggs.
He made them out of rubber, out of nitrocellulose. And, included in there was silica. Actually right here on the table, I have some examples of some silica gels. This is a, a wet silica gel It’s kind of rubbery so I can just,
you know, carve out a piece. It is 97% alcohol inside of its pores. And then the remaining 3% solid is amorphous silica. Just– – Can I touch it?
– Yeah, absolutely. It’s kind of rubbery. Not that strong. – So was I cracking it there or was it already kinda cracked? – Yeah, you just, no–
– Oh whoa, it’s very easy to break. Very crumbly. – The next step is to replace the alcohol in the gel with liquid carbon dioxide. – We’re about to see liquid CO₂. – Liquid CO₂ has the advantage of being non-flammable, plus it’s got a low critical temperature. – Open it up, and–
– Yeah, I see it flooding in there. – Yeah, it’s flooding in. There it goes.
Just another solvent. [Vibration.] – You can clearly see that it’s so much cooler on top. – What temperature is it on the bottom?
– We’re at 600 right now? – 600 degrees Celsius.
– 600 degrees Celsius, that’s 1250 Fahrenheit right now. – Notice where the bunny is melting. It’s melting right on that edge where the heat’s, like, the flame is kind of crawling up and over. – So, yeah, that’s – Oh! Bunny down! [Laughs.] – Well, not a bad result.
– Not a bad result at all. – I’m interested in in tasting some of this chocolate here. ( – Gross.) – Is it hot? – It’s warm.
– Warm. – And delicious.
– Like fondue. – Mm-hmm. That was great. Once the liquid CO₂ has filled all the pores of the gel, it’s time to take it supercritical. – It was, I would say, a kind of a spiritual experience the first time that I saw a supercritical fluid. – We’ll get to that here. – [Laughs.] I love how much you’re into these autoclaves.
– I love aerogels. To make a supercritical fluid, we can heat this with a hairdryer actually. [Hairdryer blows.] As we approach the critical point, the surface of the liquid becomes kind of blurry. – Weird, huh? – That is like weird waves in there, yeah. I’ll speed it up so you can watch the surface disappear altogether. You’re now looking at the supercritical fluid of CO₂. In this state, the CO₂ can be vented without affecting the solid structure, and what you’re left with is aerogel. ♫ – If you look at aerogel on a light background, it’s almost impossible to see,
because it is pretty transparent. But if you look at it on a darker background, then you can see that it has a slight bluish color. And, it’s bluish for the same reason that the sky is blue, because all those tiny little nanoscale structures, they scatter the light according to Rayleigh scattering. And, the intensity of light scattered is proportional to
1 over wavelength to the power of 4, which means it scatters shorter wavelengths, like blue, much more than it scatters yellow or red. And, for that reason, aerogel looks opaque in the ultraviolet and transparent in the infrared. – Now, what do you think this would look like
if I held it up to the blue sky? What do you think we would see?
Would it look ultra blue? No, it looks yellow. And that’s because the aerogel is actually scattering out that blue light, and so what passes through and makes it to our eyes is the longer wavelengths like the yellows and oranges. It’s basically the same effect as looking at a sunset When you see the yellows and oranges of a sunset, it’s because the blue light
has already been scattered out by the atmosphere the light had to pass through
before it reached your eyes. So effectively looking at aerogel against blue sky
is like looking at a portable sunset. The nanoscale pores of the aerogel are also what makes it such a good thermal insulator. ( – Three.) – That’s awesome. – Does that look hot?
– It’s definitely hot. – You might think that because aerogel is largely comprised of air, like 99% air, that it has the same thermal properties as air,
but that is not correct. It’s actually a better insulator than air is. – That’s because the width of the pores is smaller than the distance air molecules travel on average before colliding with something. Their so-called mean free path. Hence, it’s really difficult for the hot, fast-moving air molecules below the aerogel to diffuse through it and transfer heat to the top of the aerogel. This is called the Knudsen effect.
– It is so weird because you know, you don’t expect something that’s transparent to block the heat that well, but this really does. – And that’s why NASA used aerogel insulation on the Sojourner Rover, Spirit and Opportunity, the Curiosity Rover, and they plan to use it on future missions to Mars. – Why does it need insulation?
– The electronics, because they don’t want the electronics to get cold during the cold nights on Mars – NASA has also put aerogel to more exotic uses, notably to catch dust from a comet
as part of the Stardust mission. – So the particles were traveling about six kilometers per second relative to the aerogel So when they hit the aerogel, because the aerogel’s
a very low density material, very, very porous material, the particles actually enter the aerogel,
and as they travel through the aerogel, they basically break apart the network that makes up the aerogel and they lose energy in the process and eventually come to a stop. This is good for capturing particles, because if a particle like that were to hit a solid surface then it just stops, you know, immediately. – It just vaporizes.
– And vaporizes. – So should we expect to see aerogel in our everyday lives anytime soon? – One of my running jokes is when they build skyscrapers in Antarctica, they’ll use aerogel as thermal insulation. [Both laugh.] – Why do you say that? – Well, because then they’ll really care about how, just how thermal efficient it is
because it would be so cold there. – Right. – So instead of having, you know, ten feet of fiberglass insulation, you could have six inches or something of aerogel. – Scientists are currently working on reducing costs and increasing durability. – And that’s true. They do have some elasticity.
– Okay. – Yeah, so there we go. So it is not hard to break. – They’ve already made a lot of progress.
For example, original silica aerogel is hydrophilic. – There we go. Now this is a hydrophilic aerogel. – So once we’ve done this, is that piece of aerogel ruined now? – Pretty much. – But there are ways to make it waterproof. So if you want to see that and all the other next generation aerogels, then subscribe to the channel and this may be the start of an aerogel trilogy. ♫ [Subtitles credits: 雜碎 Chop Suey, ]
[Translation credits: ]


  1. black coffee November 5, 2019 at 2:00 pm

    OMG! Dr. Stephen (2:30) looks so different after a year (in a good way)!

  2. 王Anru November 5, 2019 at 2:12 pm

    He looks like Eli from why women kill

  3. Subto PewDiePie November 5, 2019 at 2:17 pm


  4. Rudi Pohan November 5, 2019 at 2:57 pm

    Nata de coco?

  5. blafiman November 5, 2019 at 3:01 pm

    can you smoke it ?

  6. 정우영 November 5, 2019 at 3:38 pm

    오우..농담의 질이다르네

  7. Dima Kabbout November 5, 2019 at 4:04 pm

    Is it or did I really wanna crush it because it looks like jello

  8. victor bruun November 5, 2019 at 4:17 pm

    wanna try something really "hot" (not that anyone is entirely sure if its heat… but 200 watts plasma make tungsten into gas in a second of two.). Go to the SAFIRE plasma lab.

  9. Pascal Schwarzer November 5, 2019 at 4:17 pm

    I would've rather ate those bunnies

  10. Awa Amd November 5, 2019 at 4:41 pm

    Thats illegal

  11. Aaron#1 November 5, 2019 at 5:01 pm

    Plants take in carbon dioxide and let out oxygen…so if u pour liquid CO2 on the plant would it have the same result would it just let all that out as oxygen or would it not do anything or am I just overthinking🤔

  12. Big Smoke November 5, 2019 at 5:04 pm

    Aerogel:99.8 air

    Lays:99.9 air

  13. Ahmed Tarek November 5, 2019 at 6:14 pm

    how much does it cost

  14. BlxrredTaco November 5, 2019 at 7:00 pm

    is this even possible??

  15. TMT #retard November 5, 2019 at 7:01 pm

    Finally someone touched a cloud

  16. SLUSHI SYNERGIES November 5, 2019 at 7:15 pm

    But who cares

  17. Gianmarco November 5, 2019 at 7:41 pm

    Aerogel: 99.8% air

    Plankton: 1% evil, 99% hot gas

  18. SiNgH iS kInG November 5, 2019 at 8:21 pm

    When I just find an lucky ice cube from fridge

  19. BadVibesForever Xo November 5, 2019 at 8:52 pm

    He made them out of egg's he made them out of cell's

    Did he make one out of ass?

  20. AstronautK3nny November 5, 2019 at 8:54 pm

    What if you would have helium instead of air

  21. 16 subs without a single video November 5, 2019 at 8:55 pm

    I'm pretty sure a grain of salt is lighter

  22. Jeddo Christy November 5, 2019 at 9:13 pm

    유튜브: 와.. 이거 쩌는데? 너도 봐랏 ㅋ

  23. Olivia Svensson November 5, 2019 at 9:18 pm

    Aerogel: im 99,8% air

    Lays: im about to ruin this whole mans career

  24. NerdyCookieツ November 5, 2019 at 9:52 pm

    I can pick up a tiny crumb and it'll be lighter

  25. Will Cockins November 5, 2019 at 10:26 pm

    The first people to hold the sky in their hands😂😂😂

  26. BrashNZ November 5, 2019 at 10:26 pm

    So exactly how "solid" is this stuff. I mean, it looks like it should be spongy or squishy. (surely a piece of foam rubber sponge is still technically a solid).

  27. Momi Mama November 5, 2019 at 10:41 pm

    Dr nozman

  28. Luca Fox November 5, 2019 at 11:46 pm

    my 10 bags from my dealer weigh less

  29. Rilind Lindij November 5, 2019 at 11:50 pm

    this material is heavien't

  30. Luis -Kun November 6, 2019 at 12:58 am

    F R O Z E N A I R

  31. BeastyBeard November 6, 2019 at 1:03 am

    I feel like this is the new eco-friendly solution to housing insulation.

  32. Creepystone Animations November 6, 2019 at 1:04 am

    Lays: You're weak

    Aerogel: I'm you!

  33. Zucchini November 6, 2019 at 1:46 am

    Aerogel: I’m 99.8% air
    Lays: pathetic

  34. Antonio the Wabbit November 6, 2019 at 3:09 am

    so this is 1.22 grams correct
    what about those little green one gram cubes we had in elementary school

  35. LILBOEG VEVO November 6, 2019 at 3:28 am


    Edit: I didn’t actually edit this dumb

    Read more

  36. عصفور ِ ِ November 6, 2019 at 4:16 am

    99.8 air! Huh still lower than lay’s chips bag

  37. Axel Marz November 6, 2019 at 4:27 am

    is aerogel in the parker solar probe ?

  38. fluffyjar November 6, 2019 at 5:10 am

    Imagine if a gaming mouse was made from this

  39. James Tarr November 6, 2019 at 5:52 am

    Mind blown.

  40. Scramified November 6, 2019 at 5:56 am

    My Friends: what you doin?
    Me: watching a video
    My Friends Again: what video?
    Me Again: ItS cOmPliCaTeD

  41. popff7 November 6, 2019 at 7:51 am

    Im never a person, your a person made out of… (not flesh it sounds like horrorish) Smooth and friendly! With a firefly?

  42. Super Xhaiden November 6, 2019 at 8:25 am

    Me: *sees it*

    Is iT EdIBlE?

  43. Lepoopsksk November 6, 2019 at 10:09 am

    Paper:am i a joke to you

  44. hahaha_kimi November 6, 2019 at 10:24 am

    2:28 that gives it its virginity

  45. JustPixel November 6, 2019 at 10:26 am

    Can spongebob lift it??

  46. BulletZ November 6, 2019 at 10:34 am

    Who wants to hold the aerogel

  47. Frantic Gaming November 6, 2019 at 11:59 am

    99.8% air
    Damn I know another item which has that much air…. a pack of Doritos you get like 5 in the small packs

  48. X_Grave_X November 6, 2019 at 12:40 pm

    That is ice block.

  49. Biggie Dinosaur November 6, 2019 at 12:41 pm

    Is it weird that I have the urge to squeeze it? 😂

  50. Samkit Vortex November 6, 2019 at 1:41 pm

    0:35 to add another topic in chemistry

  51. Kaung Htet Thu November 6, 2019 at 1:56 pm

    Aerogel: you are weak lays

    Lays: i'm you

  52. Matisse Ibarra Abdur-Rahman November 6, 2019 at 1:58 pm

    Wait… what if you soaked the jell in liquid nitrogen instead of water?

  53. Pain November 6, 2019 at 3:06 pm

    Aerogel: 99.8% Air
    Lays Entered the chat
    Lays: Aight bet
    Aerogel leaves the chat

  54. Feb frost November 6, 2019 at 4:17 pm

    Don't use gel for cooking food .you need lava

  55. cloudy tears November 6, 2019 at 7:17 pm

    Can i breath it

  56. zero X November 6, 2019 at 7:50 pm

    0:01 as long you're not mistaken that for this and accidentally Eating it 😅

  57. Random Person November 6, 2019 at 8:27 pm

    I hope you are going to eat those bunnies

  58. d u c k November 6, 2019 at 9:02 pm

    thats just a mf barrier block

  59. A Dwayn November 6, 2019 at 9:20 pm

    Is this a new block in minecraft??

  60. isalis gopro November 6, 2019 at 9:27 pm

    Who else wanted to see them squish the aro gell(idk how spell it)

  61. Felac November 6, 2019 at 9:43 pm

    Air blocks?

  62. Ghost Hunter November 6, 2019 at 11:03 pm

    put the bunny back in the box

  63. Francisco PENDEXTER November 6, 2019 at 11:09 pm

    Can you squish it?

  64. Aly P November 6, 2019 at 11:12 pm

    you talking 'bout jelly made me crave jello


  65. Hapi Juce November 6, 2019 at 11:17 pm

    German Chocolate is tasty 🙂 Lindt

  66. cute unicorns123 November 6, 2019 at 11:27 pm

    Him: this thing is 1.12 grams

    Me: but everyone said that a paperclip is 1 gram soooooooooo

  67. luxe November 6, 2019 at 11:29 pm

    makes me wanna eat it like jello

  68. Toilete Gaming!!! November 6, 2019 at 11:53 pm

    no chocolate bunnies were hurt in the making of this video.

  69. Jevzi November 6, 2019 at 11:56 pm

    just slightly more dense than a gram of marijuana

  70. Time Lord November 7, 2019 at 12:02 am

    Wait what about hair or paper

  71. SilentThunder5 November 7, 2019 at 12:28 am

    Lays: Finally! A worthy opponent!
    Lays: Our battle will be legendary!

  72. BrokenRainer YT November 7, 2019 at 12:28 am

    bruh ur wrong

    I'm the world's lightest solid

  73. Thereal_27 November 7, 2019 at 12:55 am

    Thanks for the spanish subtitles 🙂

  74. Al Lawlor November 7, 2019 at 1:26 am

    I thought it was a sand or salt

  75. Witty ACT November 7, 2019 at 1:50 am

    It wouldn’t make sense that it’s the lightest solid in the world when it’s 99.8% air;
    Because air is mostly oxygen and carbon dioxide and they aren’t the lightest elements/compound in the world
    Hydrogen is. So the lightest/least dense object in the world would be the solid form of Hydrogen which requires really low temperatures to get to.
    You can say that the object is lower density than air but definitely not the lightest in the world

  76. Alberto November 7, 2019 at 2:00 am

    Daily Dose Of Internet is gonna go nuts

  77. A Google User November 7, 2019 at 2:06 am

    How could you make something lighter than air if it's 99.8% air?

    Im assuming the other .2% are other materials for forming a solid

  78. A Google User November 7, 2019 at 2:06 am

    How could you make something lighter than air if it's 99.8% air?

    Im assuming the other .2% are other materials for forming a solid

  79. A Google User November 7, 2019 at 2:06 am

    How could you make something lighter than air if it's 99.8% air?

    Im assuming the other .2% are other materials for forming a solid

  80. Mason Licklider November 7, 2019 at 2:53 am

    So is no one gonna talk about how the bunny LANDED UPRIGHT

  81. Tyanxd November 7, 2019 at 4:18 am

    Eat it

  82. base marg November 7, 2019 at 4:29 am

    I disagree with your claim about it being the lightest solid ever. As i have had a nug of marijuana approx. the same size and it weighed around .22 grams less, being a 1.0 Gram nug. Marijuana is also a solid!

  83. base marg November 7, 2019 at 4:42 am

    Great video. Thumbs down however, as 'certain' strains of marijuana are confirmed lighter and even bigger. As dense no. But, your title is misleading. I want to report you for false advertising in your title!

  84. Maxwell Cone November 7, 2019 at 4:59 am

    I swear my weed weighs less

  85. Rylie Breaux-Collins November 7, 2019 at 5:09 am

    someone show this to lays hq

  86. Spark _ Donut November 7, 2019 at 7:58 am

    How about cotton candy or candy floss

  87. Raymond Bandera November 7, 2019 at 9:06 am

    So that’s the reason why products made from China is so weak.

  88. Yo Mama November 7, 2019 at 9:08 am

    Can't seem to understand the way he talked about math equations.

  89. Can i get 1000 subs with no videos challenge November 7, 2019 at 10:45 am

    Aerogel is 99.8% air

    Lays: finally a worthy opponent

  90. ROGI ROBLES November 7, 2019 at 11:45 am

    What a transparent solid

  91. midas touch of ASM November 7, 2019 at 12:10 pm

    Is it lighter than a single strand of hair

  92. Harry2Plays November 7, 2019 at 12:25 pm

    I thought holding a dust is more lighter Lol

  93. Harry2Plays November 7, 2019 at 12:29 pm

    Touching the world lightest liquid

  94. fizzyizzy1230 November 7, 2019 at 12:34 pm

    Is anybody talking about the innocent chocolate bunnies?!

  95. Hassan November 7, 2019 at 12:39 pm

    it's $23,000 per pound!

  96. QuickDigits November 7, 2019 at 1:21 pm

    Awesome stuff, got my sub 🙂

  97. Vacant Lot November 7, 2019 at 2:09 pm

    It doesn't seem the world's lightest to me. Can't those small plastic capsule things weigh the same?

  98. Enzo the inkling Doctor November 7, 2019 at 3:01 pm

    is that a solid ice

  99. ola kede November 7, 2019 at 5:04 pm

    So feathers are made of Aerogel?
    My little brother thought

  100. •ʀ ᴏ s ᴇ s• November 7, 2019 at 5:38 pm


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