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Comment by rebootthesystem | Hacker News Reader

This is neat stuff yet I am having trouble with the use of the term "material", somebody help me.

To me this isn't a new material any more than aluminum honeycomb is a new material. The material is aluminum or steel. They are then fabricated into honeycomb sheets or lattices.

I don't see it as discovering a new material but rather fabricating an existing material in a different way.

Other examples of this might be aluminum truss used in staging and the use of trussed steel in bridge building.

What is a material?

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Does it help if you think of it as an alloy of metal and air?

When you make steel all you are doing is forming various crystal structures, and grains. Martensite, Ferrite Austenite, Cementite, etc. They are all the "same" material (iron and oxygen and carbon), yet if you figure out a new way of arranging their shapes "just so" you can say you invented a new type of steel.

This is the same way - they figured out a new way of arranging the atoms, so it's a more or less a new material.

(I do see your point of course, and this is more macroscopic than grains in steel, but I think it's not unreasonable to call it a new material.)

Thanks for all the input. I think I found something to quiet my mind:

Raw Material vs. Fabricated Material.

To me this distinction makes the universe come back into alignment. Honeycomb Aluminum is a fabricated material made from aluminum. Denim, a fabricated material made from cotton. A lighting truss, fabricated material from aluminum. The microlattice product from the article is a fabricated material from steel.

Works for me.

Thanks.

You don't need to be so literal. When you look at honeycomb, for example, the manufacturers provide strength data in much the same way you'd see it for a solid metal. When you model it with finite element software, you treat it as an monolithic material - you don't model every fold of metal. In that sense, honeycomb (and this stuff) is a material in that it's used the same way. The properties of the "material" already account for its micro-structure.

Material includes the characteristics that the given shape/configuration provides. For example, denim and gingham are both made of woven cotton. However, they're different materials due to their differences in properties -- gingham's light and airy and loosely woven, while denim is rugged and more tightly woven. Composition is just half of what makes a material a material.

When I Google around, it seems that sites explaining what aluminum honeycomb is pretty consistently follow the pattern "Aluminum honeycomb is a [adjectives] material with [characteristics]."

I get what you're saying about trussed steel, but I think that's really just getting at the point that categorical distinctions are rarely cut-and-dry.

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