Solid lighter than air

[BenTheJester]

I was looking at eberron's airships and saw that they were made of soarwood, a kind of would actually lighter than air, so I wondered if there is something, in its solid form, that is lighter than air?

(I'm pretty sure there are none, but I'd like to have confirmation)



(I also apologize if I didn't ask this in the right section of the board, none of them really seemed appropriate.)

[Djinn_in_Tonic]

Aerogel is lighter than air is three times heavier than air. Light enough that a small amount of energy could cause it to fly.

[Volos]

Take anything that is normally lighter then air... such as a gas.
Freeze it.
Now you have a solid that is lighter then air.

[Crow]

Except that the frozen state is more dense, which makes it heavier.

[Demented]

If we're assuming in an atmosphere and going by weight, even air in its solid form isn't lighter than air.

A substance (or container) with enough empty vacuum within its volume could have the appearance of weighing less than air at sea level, but it would also have to be capable of surviving atmospheric pressure to be of any use...

[Cybren]

A hydrogen balloon.

...what?

[Optimystik]

A wizard did it.

[Lycanthromancer]

What's denser than teak but lighter than air?

<.< http://s54.photobucket.com/albums/g111/Lycanthromancer/?action=view&current=paris-hilton.jpg >.>

[bosssmiley]

I was looking at eberron's airships and saw that they were made of soarwood, a kind of would actually lighter than air, so I wondered if there is something, in its solid form, that is lighter than air?

Cavorite, of course.

[Spiryt]

Take anything that is normally lighter then air... such as a gas.
Freeze it.
Now you have a solid that is lighter then air.

Except that the frozen state is more dense, which makes it heavier.

Metallic hydrogen has a density of about 0.57 g/cm3, for example.

So, unsurprprisingly, it's not going to work so 'easily'.

[Mastikator]

A hydrogen balloon.

...what?

Correctamundo. A hydrogen balloon is a solid thing that is lighter than air.

[ericgrau]

Even if you have a material that's totally weightless it takes 13 cubic feet to generate 1 pound of lift. At higher altitudes you get less lift. That's why you see giant blimps with small passenger compartments in the bottom. I'd go with a gigantic hot air blimp or use magical levitation.

If you heat the blimp to 350 degrees it won't burn most materials and you'll get a pound of lift per 40 cubic feet, at least at low altitudes. Higher temperatures are only slightly better and much more fuel hungry. It should consume about a pint (1 pound) of lantern oil per hour per 100 square feet of surface area. Surface area is very roughly 3 * diameter * length. Lift is very roughly 0.02 lbs. * diameter * diameter * length, measuring in feet.

[Sharkman1231]

Correctamundo. A hydrogen balloon is a solid thing that is lighter than air.

The balloon is not lighter* than air, it contains a substance that it lighter* than air giving it a buoyant force upwards that is greater than the downward pull of gravity on the hydrogen and the balloon.

*By lighter I mean less dense.

EDIT: I <3 physics

[erikun]

I would love to see a balloon made entirely out of hydrogen.

There are no (real world) solids which are lighter than air. Solid Hydrogen, already mentioned to be 0.57 g/cm^3, translates into 570 kg/m^3. Air is 1.2 kg/m^3.

There is solid matter found suspended in the air, in the form of dust and similar particles. It is light enough to stay airborne through air currents, but that doesn't mean that it is light enough to float in a vacuum. I doubt dust suspensions would help you keep an aircraft in the air, for example.

There are numerous "floatstone" fantasy materials which are either lighter than air or simply remain airborne, if that's what you're looking for. I'm not familiar with any in D&D, though.

[Riffington]

Are we assuming 1ATM pressure?
Air is pretty compressible prior to becoming a liquid, so if we increase atmospheric pressure enough you may have better luck.

[jseah]

You could go for an SF-like explanation for a negative mass object.

Which convieniently allows everything from anti-gravity to faster than light travel and inertia drives.

[DragoonWraith]

Cavorite, of course.

Not... really. Well, I mean, in effect, but the mechanics behind it are completely different from simply being less dense then air.

Kudos on that reference though, that's pretty awesome.

[Cespenar]

Perhaps a solid material that constantly generates (through a reaction) a lighter than air gas, holding the said material aloft?

It would deplete after a while, though.

[Mastikator]

The balloon is not lighter* than air, it contains a substance that it lighter* than air giving it a buoyant force upwards that is greater than the downward pull of gravity on the hydrogen and the balloon.

*By lighter I mean less dense.

EDIT: I <3 physics

I can play the technicality game too.
I technically said "a helium filled balloon", and I meant the whole balloon with the helium as a single object, (not necessarily as a homogeneous object), which is acceptable in my opinion since the original post said, and I quote "I wondered if there is something, in its solid form, that is lighter than air?".
He didn't say substance, he said thing. A composite substance object is still a thing and its density is commonly simply its mass divided by volume.

[Sinfire Titan]

If there was a solid that were lighter than air, wouldn't it have all ready left Earth's atmosphere?

[Stormthorn]

If there was a solid that were lighter than air, wouldn't it have all ready left Earth's atmosphere?

Its underground.

Im sure of it.

Mine deeper!

[Sinfire Titan]

Its underground.

Im sure of it.

Mine deeper!

I highly doubt that planets float in space due to a solid that is lighter than air.

[Spiryt]

I highly doubt that planets float in space due to a solid that is lighter than air.

Mine does exactly that...

[Stycotl]

I highly doubt that planets float in space due to a solid that is lighter than air.

i don't think that to be the point of stormthorn's post. i think he was inferring that it was trapped underground and could not leave the atmosphere.

[Sinfire Titan]

i don't think that to be the point of stormthorn's post. i think he was inferring that it was trapped underground and could not leave the atmosphere.

I know, I was making a joke.

[kentma57]

Are we assuming 1ATM pressure?
Air is pretty compressible prior to becoming a liquid, so if we increase atmospheric pressure enough you may have better luck.

hmm... what a great use of epic level magic, increase ATM...

[Signmaker]

Porous* Foam gassed with token light gas, and chemically sealed to prevent said gas from escaping. It won't stand up to a baseball swing (or a fingerflick, really) but it works.

Or a balloon. Same principle, really.

*Redundancies are redundant.

[Mando Knight]

Are we assuming 1ATM pressure?
Air is pretty compressible prior to becoming a liquid, so if we increase atmospheric pressure enough you may have better luck.

But of course. Atmospheric density is actually rather constant at lower altitudes and common temperatures. It still varies, but there's a reason why low-speed airfoils are studied using an incompressible fluid assumption.

Yes, every time you board an aircraft, you're entrusting your life to an engineering crew's estimations. Don't worry, we've gotten pretty good at guessing over the last 100 years of aerospace engineering.

[bosssmiley]

I highly doubt that planets float in space due to a solid that is lighter than air.

Two words: Grubbian Physics.

And everyone knows planets float in space because of their corona of rapidly flapping wings (like, "duh" people!)

[taltamir]

solid, liquid, and gas all contain vast amounts of empty space, especially if you look at sub atomic particle sizes...

the density has a lot to do with how far away the chemical bonds (for solids, which are caused by electromagnetic force) keep atoms from each other (and thus, how much empty space is there), or just repulsion between atoms/molecules (in liquid / gas state)...
Either way, its really about how much empty space you have, to grossly over simply things...

So, make a light solid (balloon) filled with lighter than air gas (helium), or if you could, vacuum.
problem is, that a vacuum balloon collapses on itself, good thing magic can take care of that...
so you use magic to make a substance that is super light as a solid, and full of vacuum bubbles.