The possible lightest material

[Eagle9]

I wonder to know where the lower limit for solid substances’ density is. We know that some solid materials are lighter than liquids (ice, wax and etc), but can the solid material in principle be lighter than air? For example the density for Carbon nanotube is at least ten times less than water’s one (data taken from here: http://en.wikipedia.org/wiki/Specific_strength ). What Physic’s laws say about this? Is substance’s lower boundary for density somehow restricted?

 

[cgk]

The point about a gas (say, air) is that a given amount of gas molecules will take up any volume you offer it. That means that there is no lower limit to the density of a gas. This cannot be beaten by any solid.

Or are you wondering whether any solid could in principle have a density of less than about 1.2 kg/m^3? (air density under standard circumstances is somewhere in that region). In that case the answer is "in principle most likely yes" (think of a hard foam filled with helium).

 

[Borek]

http://en.wikipedia.org/wiki/Aerogel

Check "Types/Silica" section.

 

[cgk]

http://en.wikipedia.org/wiki/Aerogel

Wow, that is cool!

 

[Eagle9]

cgk

Or are you wondering whether any solid could in principle have a density of less than about 1.2 kg/m^3?

Yes

Borek

http://en.wikipedia.org/wiki/Aerogel

Great! Almost as dense as air! Perhaps very soon the scientist will invent even lighter material that will enable us to make some armor that we will wear and fly in air

 

[Borek]

Great! Almost as dense as air!

Quite the opposite - air is almost as dense as the lightest aerogel made up to now.

 

[Drakkith]

Great! Almost as dense as air! Perhaps very soon the scientist will invent even lighter material that will enable us to make some armor that we will wear and fly in air

Hrmm. If only it could work like this... =)

 

[Eagle9]

Could you please tell me where is it possible to find information about Aerogel’s other properties? I need to know the value of tensile strength for this material but these web-sites:
http://en.wikipedia.org/wiki/Aerogel#Silica
http://en.wikipedia.org/wiki/Tensile_strength
Do not provide such information

At this site:
http://eetd.lbl.gov/ecs/aerogels/sa-physical.html
It is written that tensile strength for Silica Aerogels is 16 kPa for the density of 0.1 g/cm^3, but what about the Aerogels with the lowest density- 1.9 mg/cm^3?