Some time ago, I seem to remember a Discovery Channel program in which they showed a solid object created from a material lighter than air. This cube (I believe around 1-1.5") floated in mid air as scientists were studying it. As you might imagine, this object didn’t look like a toy block, but was very – well – light in appearance.
Does anyone else know what I’m talking about, or did I dream this up? This came to mind when I read Marilyn VosSavant’s column in yesterday’s Parade. She mentioned a very light, very strong material called Aerogel. Is this the stuff I’m thinking of?
A “solid lighter than air” is, IMO, going to be very hard to come by. I think you misunderstood some part of what you saw.
Solids, by definition, have their atoms/molecules very close together while gases (e.g., air) have their molecules widely scattered. If you’re losing the war at the atomic level you’re not going to win at the macroscopic level.
I think you either saw 1) a very light solid, such as aerogel, being supported somehow, or 2) a demonstration of superconductivity which routinely includes suspending a superconducting solid over a magnetic field.
Aerogel’s pretty amazing stuff, but being lighter than air is not one of its features. It’s essentially a very finely dispersed solid. It’s interstices are filled with, you guessed it, air.
Here’s an idea that just occurred to me – maybe they immersed a chunk of aerogel in, say, helium and allowed the helium to displace all the air in it. Then when they took it out it would take a while for the helium to diffuse out so they essentially had a helium balloon made of aerogel. For a while at least. That would probably float. Could that have been it?
I would think that a lighter than air solid wouldn’t float in mid-air. It would probably float up to the ceiling. something being suspended magnetically or otherwise might float in mid-air. However, I have to believe that a lighter than air solid is not impossible, or at least not impossible for the reasons stated by pluto. A very light solid, like balsa wood, would float on a very dense gas, like radon. So I don’t agree with this statement: “Solids, by definition, have their atoms/molecules very close together while gases (e.g., air) have their molecules widely scattered. If you’re losing the war at the atomic level you’re not going to win at the macroscopic level.”
Sorry, Lance, but according to my Chem-Physics Handbook radon has a density of 9.7 g/l and balsa wood comes in at a whopping 110 g/l. So even your very light solid is ten times more dense than your very heavy gas. (Air, BTW, is about 1.3 g/l – a factor of about a hundred. And the OP did describe a solid floating in air.) And, once again, the interstices in your balsa wood are filled with air. Exclude the air from consideration and the density would be similar to that of ordinary wood.
Theoretically, I could make a hollow cube (or sphere) of some very thin material such as mylar and get a density as near as I cared to that of air itself, because it would be mostly air. But I don’t think that’s what was being asked.
Your point about floating in mid-air is right on the money, though.
Air would be very tricky & prat near impossible to define as well as to structure so that the results were consistent.
But you are probably missing the point, the point is gravity pulls things downward, all you need is no gravity & then you got tons of stuff lighter than your ‘air’.
I did a web search, and got conflicting answers. This NASA page says aerogel is “a solid that can be made lighter than air.”
However, This page from LBL says “Larry Hrubesh prepared the worlds lowest density silica aerogel (and the lowest density solid material). This aerogel had a density of 0.003 g/cm3, only three times that of air.” This statement refers to the state of the art in the late 1980s though, so who knows.
I think, theoretically, you could make a sphere of say, aluminum, or another light metal, and if you make it big enough, with thin enough walls, and vacuum pump it, it would float on air.
But I don’t think that’s really what the OP was about…
Aerogel is just a porous material like a sponge. It is more than 99% air by volume, but that last bit of material is still solid, which means aerogels will never be lighter than air. The only exception is if advances in manufacturing techniques allow to us to create micro vacuums (or near vacuums) of sufficient volume within it, like what Dave Swaney has described.
Back to the OP, I do in fact remember that particular program which mentioned aerogels on the Discovery channel. It was an episode of The Next Step I believe, and I don’t think it has been shown any time in the last five years. The shot with the aerogel floating in midair was created with the help of a little updraft in a fish tank. The stuff is still quite amazing however. I hear there is the possibility that it can be manufactured to be transparent under low gravity.
Hey I saw that show on the Discovery Channel too! It was years ago. They were mainly talking about Buck molecules or Buckeye molecules. Something like that. I’m sure some of you people must know what I’m talking about. If I recall correctly I remember seeing a piece of material that was white and sort of floating in air but not quite all the way. I remember them saying something about making a solid lighter than air. I think it was smaller and thinner than you described, but we are definately talking about the same show
Could one make aerogel filled with Helium? That should be easier than making vacuum cavities. One could make solid airships!
I recall a sci fi novel which mentioned lighter-than-air foam used for packaging because they are so cheap to make thanks to nanotechnology. Of course it all floats up into the sky and hang around forever.
I’m glad some people remember what the Discovery Channel program I was watching. It was one of those evenings where I was channel surfing, so I didn’t get the whole story. Thanks, Zor, for refreshing my memory.
Maurique, could you be thinking about Buckminster Fullerine? I believe that is a molecule useful in medicinal radiation therapy. I beleive it is in the shape of a soccer ball, giving it unusual durability. It’s also called a “Buckyball.”
“Buckyballs” are molecules made of carbon arranged in a round shape just like a soccer ball. They were named after Buckminster Fuller, who came up with the shape of a geodesic dome many years ago.
Start with a hexagon with a carbon atom at each corner. You could keep adding hexagons to it, so the carbons end up in a flat sheet. But what if you have a pentagon with six hexagons around it? It wouldn’t be flat, but would form a cup shape. Then add more pentagons and hexagons until it closes back on itself. What you’ll end up with is exactly like a soccer ball, with several (how many?) hexagons and six pentagons. It has 60 corners, so the simplest Buckyball is C60.
If you put in enough packing material, the box itself floats. FedEx has a special rate list for this: they pay you to ship your package, but not as much as you’d think, since there is some bulk, and above 30,000 feet, the package is no longer lighter than air.
[geek mode=geometry]The shape of the molecule and a standard soccer ball is what’s known mathematically as an “equilateral truncated icosahedron”, and it consists of 20 hexagons and 12 pentagons. It’s what you get if you take an icosahedron (20 triangular faces; one of the five Platonic solids), and slice off each corner so that the faces turn into hexagons and the corners turn into pentagons.[/geek mode]
