Aerographite: six times lighter than air, conductive, and super-strong
extremetech.com
extremetech.com
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.
I think like a sponge in the photograph it has a fair amount of air in itself.
Just a guess though.
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.
You are confusing density with buoyancy.
What is the displacement of the aerographite samples? The article doesn't say, but the samples are small enough that I'd guess the forces of moving air (breathing near the sample) is more problematic than forces of buoyancy.
I don't know, if you coat a plastic with air, does it get heavier?
So the weight is non-zero, but it's actually negative in our atmosphere. It's mass is positive.
It's the same thing here. When they say it's lighter than air, they're counting the whole structure's volume, with all its holes in it. When you put it in air, and the holes fill up with air, the question then becomes whether the rest of it is lighter than air on its own. (Probably not)
1. http://news.ycombinator.com/item?id=4260778
2. http://www.uni-kiel.de/aktuell/pm/2012/2012-212-aerographit-...
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?
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/ProductDi...
Mr. A. Wolfram says that is a volume a 80 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.
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.
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.
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.