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: ]

100 comments on “World’s Lightest Solid!”

  1. Ken김기원 says:

    Can u eat it?

  2. August Sanchez says:


  3. WDP IMJM says:

    알고리즘이 나를 인도하였다

  4. Denton Belbin says:

    Does it have any properties or properties that could be introduced to the Aerogel® that could make it a candidate for the next generation in commercializing super capacitors for either quantum computing or power storage purposes? Just wondering because the informative look into Aerogel® mentioned of its ability for heat and cold insulation and where super capacitors are at right now they need liquid gasses to assist. This product could change the whole game.

  5. flobeeone kinobee says:

    CGI Trick

  6. Matthew Michael Morrell says:

    Where do u get dis

  7. 金劝和 says:

    it's awesome

  8. David Guymon says:

    I want a ton of this!!!!! TAKE MY MONEY!!!!!!!!!!! This is so cool. I'd like to have my whole house insulated with this!!!!

  9. CHEN晨 says:


  10. roser says:

    Before you read the comments,

    The most liked comments are a comparison between aerogel and lays:P

  11. HeroScorp says:

    What’s up with the halo reach music in the background

  12. Zafarullah Awan says:

    America lovely …

  13. Zafarullah Awan says:

    Is there solid hydrogen ?…

  14. Zafarullah Awan says:

    Is there solid hydrogen ?….

  15. Joe Burton says:

    Yo that's dope af

  16. Jimmy Flores says:

    I would love to see how the research towards "gecko skin" and graphene is going along; when you do some reseach into them, you will be amazed.

  17. Mar.c0 Andr4.d3 says:

    If u take out all the air from it. Would it float IN AIR?

  18. Rice Gum says:

    He's holding air

  19. Toaster Thingy says:

    What if you put the aerogel in a vacuum chamber :O

  20. Jonathan Smith says:

    Secret of the Burning Bush Revealed 🤔

  21. Jonathan Smith says:

    Star Trek reality

  22. Mario CóneBora says:

    And they said you can't touch clouds and they tried to ruin my childhood… HA idiots

  23. Luna says:

    Which is heavier, one kilo of aerogel or one kilo of gold?

  24. Alex Calder says:

    why burn the bunny ..

  25. astrotrain21 says:

    At one point, you confused jam (US jelly) with jelly (US jello-o) in your video.

  26. Alejandro Salamanca says:

    I want to eat it

  27. Manisha Rana says:

    Instate of normal air if you use helium it will be less denser then air

  28. James Well says:

    이거 노무현 전 대통령님 비하 영상 아닌가요? 개씨발놈들이 뒤질려고

  29. Aloof legend says:


  30. Emanuel Garcia says:

    Just imagine how a solid fart would look like

  31. 돌하루방 says:


  32. Max Choi says:

    I don't disagree with the aerogel's thermal insulation strength but at least you should have tested it with the glass Petri dish had the same thickness.

  33. Transforming wale says:

    heat: does nothing
    jell: confusion spell!!!!

  34. まかろん says:


  35. 임민수 says:

    비정질규소인가??? 뭐지 궁금해….궁금해!!!!!!!!

  36. Jayde sanchez says:

    Could you it the aerogel

  37. Jarel Sajata says:

    Can we use aerogel as an alternative glass panels for skyscrapers?

  38. Am0r says:

    When you mine a Minecraft cloud.

  39. 꺅꿍 says:

    와 촉감 존나 궁금하다

  40. Don Ren says:

    why am I watching this at 2AM ..

  41. Zay Wat says:

    Well that's a subscribe right there 🙂

  42. ItsByko says:

    Okay, but could this theoretically be used for sound deadening material?

    Need to replace these egg cartons

  43. A Gonzalez says:

    Ok YouTube I watched this, now stop suggesting it!
    To be fair it was interesting…

  44. Terra Nova Rain says:

    You have to use kevlar with it to block infrared super insulation 🤩

  45. Frandexter Gaming says:

    Lift a 100ft by 100ft by100 ft of aerogel

    Pretty light right?

  46. Byron Thompson says:

    I've seen weed less dense

  47. 원우지 says:

    이게 왜 뜨누 ..? 잼나네ㅋㅋㅋ

  48. Mike Hunt says:

    Would be great insulation in my house or coffee mug!

  49. Ahanu Coage says:

    I want to eat it.

  50. D4_rker says:

    is it me or he kinda looks like elon musk in this video

  51. Sam Hay says:

    Can I build a flying submersible r.o.v. out of this substance. Would make a great delta wing

  52. 어텀 says:

    어휴.. 내가 유튜브를 많이 보긴하나보다.. 이런 과학적인 것 까지 보고있네…

  53. Park주의사항 says:

    hmm interesthing

  54. Micah Jones says:

    the structure looks like subspace

  55. daniel ash says:

    Aria gel housings?

  56. Flofy387 says:

    Amazing what science brings up… 😀

  57. Korekshan Radio says:

    Imagine this material in the state of a condom

  58. Burak & Gizem says:

    abi bu işi tam anlamı ile yaptığınızı düşünmüyorum şöyleki dünyanın düz olduğu şu zamanlarda tepsi değil bak düz dümdüz olduğu vakitler aqrasında bu dediğinin mantığının hiçbir özverili yanı olmamasına rağmen amma velakin katha selakin yani aslında demem o ki şu vakitlerde burçlar ve dönenge zamanlarında basit olayların çerçevesinde dönen birtakım o9laylar esnasında senin bu yaptığın deneye ne sikemne yaradı

  59. It'sAJoker says:

    I thought a paper clip was the lightest solid

  60. True Janey Sue says:

    Now that's cool!

  61. Alannah Frederic! says:

    Steven: this is the lightest soild
    Me: so you froze your hot breath

  62. Alex Cooke says:

    It should be possible to print a house using this and another substance.

  63. Eric Booth says:

    Anybody else hear the Halo Reach music around 8:15? I’ve also heard a TV show use the same music. I guess Bungie just remixed a sample tune.

  64. E hhh says:

    Great informational video

  65. Antler Assassins TV- Bowhunting Television says:

    Trilogy renamed:
    This guys Hard on for Aerogel

  66. Original Man says:

    So why the hell were we using asbestos .

  67. Kushman 420 TV says:

    Airogell bullets

  68. puru pokhrel says:

    Fire fighters should wear suits of air jell if heat diffuses through that slow.

  69. MosquitoHunter says:

    I wonder if this would make effective insulation for firefighting gear?

  70. 타마 says:

    에어로졸이랑 에어로젤이 같은건가요? 전 다른걸로 알고 있는데요…

  71. 류제란 says:

    와 너무 사랑스러운 물질이다 ㅜㅜㅜㅜㅜㅜㅜ

  72. Blaçk Màsk says:

    Lay's has entered the chat..

  73. Ollie Cole says:

    I was looking at buying this as its pretty cool, then I realised it costs more than Gold

  74. currupipi says:

    what about noise insulation??

  75. Aurelia Alexandrina Anghel says:

    You could use this to go into the middle of the earth.

  76. Josue Salinas Ochoa says:

  77. Jasmijn ariel says:

    If it is solid…? Put it under a press 🤣

  78. 최요섭 says:

    mysterious youtube
    algorithm bring me here

  79. Filip Petrucha says:


  80. freddyzdead1 says:

    I'm sorry, I just can't abide someone who calls himself "Veritasium". Why don't you just go all the way and call yourself "god"?

  81. Esther Iavazzo says:

    I don't know why but i wanted to see him crush it for some reason..

  82. Jude Matteur Fernandez says:

    Hey guysss can you suggest a research for aerogel?

  83. Matt George says:

    What pressure do they do each piece? Is the pressure put on with the Co2 or is it regular air?

  84. Man-About-Sound says:

    lol. "i'm gonna taste this chocolate"…."gross" hahaha

  85. Amir Ali says:

    hello man how are you

  86. Aaron Georgevich says:

    6:12 "gross"

  87. NightcoreHardstyle says:

    Is that the substance using which the face glass of a vulcanologist's suit is made of?

  88. Marksmithwas12 says:

    So you're saying, that this solid is 99.8% a gas?

  89. Vinton Lindo says:

    Modern Alchemy right before our eyes 😴 this reminds me of the FIRMAMENT and something called the (Blue) Sky Crystal

  90. Sagar bara Sagar says:

    Show erogel test of strength, atmosphere resistance, torsion, as well as possiblity?

  91. JJ Tatum says:


  92. you are here says:

    Can't wait to see the nex one in the series. Please keep going! Thank you! Been fascinated by aerogel forever.

  93. Matt Davis says:

    I want it

  94. Steven Sears says:

    8:00 I hear the drums of Halo

  95. Chil fghfh says:

    Bruh got a barrier block

  96. lassi kokkonen says:

    What kind of chocolate is that
    My chocolate melts on my computer fast

  97. Stan TheObserver says:

    WONDER BREAD kicks this and Lay's but. You pick up a slice of Wonder Bread and you float.

  98. Stan TheObserver says:

    You have the $10,000 camera and the guy filming you is using an

  99. DanielinLaTuna says:

    So if the bunny was on a platform with walls made of aerogel too, it shouldn’t melt via convection?

  100. Leo Ying says:

    i probably shouldnt show this to my pet bunnies

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