I read this article last night and I can’t get my head around it. How can something be 7 times lighter than air but is a solid?

Graphene aerogel is seven times lighter than air, can balance on a blade of grass

or is it a big hoax?

“lighter than air” – why doesn’t it float then?

I don’t know and thats why I can’t fathom it out

Is it a witch?

[naive understanding]
The aerogel itself is less dense than air but is also air permeable which means that outside of a vacuum it will absorb air and therefore be heavier than air. I guess if it could be made and sealed without absorbing air then it would float (assuming the seal was also lighter…).

[/naive understanding]

I agree – that’s how I read it too.

So much like a sponge is less dense than water and floats, until it’s saturated, then it ‘sinks’?

“lighter than air” – why doesn’t it float then?

Depends how many particles of “air” you’re talking about. The air particles are also individual and so lighter than the Graphene Aerogel item as a whole.

Note, the original paper makes no claim about being lighter than air. The naive understanding above is a relatively good explanation.

Definitely not a hoax. Different types of aerogels have been around for a very long time (since 1931), they’re just very expensive to produce.

The naive understanding above is a relatively good explanation.

Haha… That’s some great damning with faint praise! 🙂