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Aerographite: six times lighter than air, conductive, and super-strong
- StavrosK 14y agoHow many times less dense than air is helium?
- regularfry 14y agohttp://www.wolframalpha.com/input/?i=density+of+air+divided+by+the+density+of+helium http://www.wolframalpha.com/input/?i=density+of+air+divided+...
- wtvanhest 14y agoFor those that have studied physics in depth: The article says: "5,000 times less dense than water, and six times lighter than air"… so what does it mean by lighter than air exactly? I presume in means that if it were in a vacuum that it would have less mass than whatever its outside edges of volume would be? That seems misleading since if you break the material down to the smallest piece, then compared air volume to that piece it wouldn't actually be lighter right? Am I thinking about this correctly?
- adrianN 14y agoWhat's the smallest piece? A carbon atom? The only reasonable way to compare densities is to take a sizeable chuck of the material and compare it to the same volume of a different material.
- jws 14y agoWe've been down this road before. I think the misleading part is that it doesn't displace air to any significant extent. By this logic, a roll of chain link fence is three times lighter than water[1]. But it still sinks. EOM [1] Calculations follow… 50 feet of 6 foot tall 9 gauge chain link fence rolls into an 18" diameter cylinder 6 feet tall and weighs 216 pounds. http://www.homedepot.com/webapp/wcs/stores/servlet/ProductDisplay?productId=202024344&storeId=10051&langId=-1&catalogId=10053&ci_sku=202024344&ci_kw=%7bkeyword%7d&kwd=%7bkeyword%7d&cm_mmc=shopping%2d%5f%2dgoogleads%2d%5f%2dpla%2d%5f%2d202024344&ci_gpa=pla#.UJPECrQ8D8s http://www.homedepot.com/webapp/wcs/stores/servlet/ProductDi... Mr. A. Wolfram says that is a volume a 80 gallons. http://www.wolframalpha.com/input/?i=volume+of+a+cylinder+18+inches+in+diameter+and+6+feet+long+in+gallons http://www.wolframalpha.com/input/?i=volume+of+a+cylinder+18... Water is about 8 pounds to the gallon, so the water of equivalent volume would be 640 pounds. Steel fencing is one third the density of water! Write the press release! Sorry about the units, world, at least I didn't break into microfortnights.
- jopt 14y agoGreat analogy, helped me understand why I felt this whole six times lighter thing was strange.
- smoyer 14y agoIf you break it down to the smallest piece, you're talking about Carbon atoms with an atomic mass of roughly 12 versus (mostly) Nitrogen and Oxygen with approximate masses of 14 and 16. So it's lighter as atoms but not by six times. Most of the Oxygen in our atmosphere is O2, so there's a bond and space between the atoms as well as space between the molecules and others. In the same way, perhaps the carbon is more like closed cell foam that has voids that exclude other atoms. These voids have no mass but contribute to the effective volume.
- alexchamberlain 14y agoCan I ask a stupid question... If it's lighter than air, does it float?
- jstalin 14y agoThat was my initial thought. If it's lighter than air, it must float...
- jws 14y agoIt does not displace a significant volume of air, so no steampunk airships for you. But I'll bet breezes blow it around.
- windsurfer 14y agoI wonder if you could wrap the sponge in a balloon-like thing and then take away all the air inside. That would likely float, if the material was strong enough, no?
- pyre 14y agoYou'd have the weight of the balloon-like thing that you wrapped it in though.
- peeters 14y agoAnd yet Zeppelins still fly.
- pyre 14y agoI never said it was impossible, just that it's another consideration. If the Zeppelin's structure was too heavy it wouldn't fly, no?
- Someone 14y agoIn the limit, that is zero. Area goes as O(N^2), volume as O(N^3), so if you make it big enough, you could wrap it in a meter of solid steel, and it would still float (guesstimate: a liter of this would lift about a gram of steel, so a cubic kilometer would lift about 10^12 grams or 10^6 tons of steel. You would need 6*10^6 square meters of cover, so you could use 160 kg steel per square meter => you will need something much bigger than a cubic kilometer to get at a meter of steel) Your real problem is keeping the fabric from being pushed in. It does not matter much, but for that, you may not need to fill the whole thing with stuff.
- Stratoscope 14y ago> six times lighter than air If it's lighter than air, doesn't it float away? Wouldn't this make it a bit hard to work with? Why doesn't the article say anything about this obvious consideration? OTOH, the piece in the photo with the drop of water does not appear to be trying to float away - unless it's the water drop holding it down. So maybe it isn't lighter than air? Or is the piece glued down? > Non-conductive objects, such as plastics, could be coated with aerographite to make them conductive — without gaining weight. While the material may be very light, I'm certain its weight is nonzero (and non-negative). This doesn't even make sense. Fascinating material, dumb article.
- sylvinus 14y agoI think it's probably lighter than air if you weight it in a vacuum. I think like a sponge in the photograph it has a fair amount of air in itself. Just a guess though.
- joesb 14y agoAir also has a fair amount of air in itself. If 1 cube of a meterial has x% aerographite + (100-x)% air, while air has x% air + (100-x)% air, the material is still going to be lighter than air.
- jpdoctor 14y ago> If it's lighter than air, doesn't it float away? You are confusing density with buoyancy.
- Stratoscope 14y agoCan you explain a bit more and help me with my confusion? Thanks!
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- jpdoctor 14y ago
- ph0rque 14y agoIf a piece of aerographite were to be sealed on the outside, and all the air removed, then yes, it would float. But without this treatment, the air permeates the microstructure, and it does not float.
- kps 14y agoSo, the question is — if you take a zeppelin-sized chunk of aerographite, seal the outside, and evacuate the air, will it hold up to the pressure?
- ph0rque 14y agoYou don't even need aerographite for that: http://www.dangermouse.net/gurps/zeppelin/vacuum.html http://www.dangermouse.net/gurps/zeppelin/vacuum.html However, you need a material strong enough not to implode due to the outside pressure of air. Not sure how good material tech is for that. Even if it were strong enough, you would have constant "leaks" of air into the vacuum cells. So you would need a vacuum pump working all the time. Still might be worth it, though.
- js2 14y agoPrevious discussion[1] from when the paper was press released[2]: 1. http://news.ycombinator.com/item?id=4260778 http://news.ycombinator.com/item?id=4260778 2. http://www.uni-kiel.de/aktuell/pm/2012/2012-212-aerographit-e.shtml http://www.uni-kiel.de/aktuell/pm/2012/2012-212-aerographit-...
- eliben 14y agoNanotechnology is awesome, but most of it seems to be in early research stages. Any good references for nanotechnology products used commercially today?
- deleted 14y ago[deleted]