The darkest colour in the world is darker than Vantablack

Following is a transcript of the video.

Narrator: Believe it or not, this is a diamond. And the reason you can’t see it is because it’s covered with the darkest colour on Earth. In fact, this material is so dark that it captures at least 99.995% of incoming visible light. But why is it covering a $US2 million diamond? And how was it made in the first place?

Narrator: You may remember this colour, Vantablack. It was unveiled in 2014, and media outlets called it the darkest colour in the world. But this colour here? It’s not Vantablack. It’s even blacker. And that’s thanks to an unprecedented collaboration between science and art. It all traces back to this artist, Diemut Strebe. In 2014, she set out on a mission to find the blackest black. Her goal was to make a diamond disappear.

Diemut Strebe: This project explores how values attach to concepts and objects in reference to luxury and art and society.

Narrator: Meanwhile, a scientist named Brian Wardle was on a totally different mission. He was working with a material called carbon nanotubes, the same stuff used to make Vantablack, though he was using them to boost the thermal and electrical properties of materials like aluminium. But little did Wardle know, he was producing something even darker than Vantablack.

Strebe: Brian was looking into the optical properties of CNTs only because of the art project. And so it kind of caused, really, from this art project, the research to find the blackest black.

Narrator: The new material, which Wardle has yet to name, is 10 times blacker than any other colour ever reported. And that likely has to do with the structure of those nanotubes themselves. In this case, Wardle and his team grew them on top of aluminium. Yeah. They may not be alive, but you can actually grow carbon nanotubes. First, you cover a material with microscopic metal particles. Then you bake it at high temperatures, in the presence of a hydrocarbon gas. And that’s basically it. Carbon nanotubes will sprout out of those metallic particles, like plants from seeds.

Brian Wardle: You do it in the way we’ve done it here, you get the recipe right, you can create forests. These are very, very long aspect ratios of, like, a million. Right, the length of the tube is, like, a million, relative to the diameter. And that grows into what’s called a forest.

Narrator: That nanotube forest is the key to creating this black colour. When particles of light, called photons, enter it, nearly all of them get trapped and then dissipate as heat. That’s why when you look at this black, you see, well, absolutely nothing. No shadows, no ridges, just black. And that made it perfect for Strebe’s diamond-vanishing project. In fact, Wardle’s team followed the exact same procedure to grow those nanotubes directly onto a diamond. And that’s pretty wild when you consider this:

Strebe: Both is made of carbon. It’s the same element, just the different atomic letter structure, makes them so extreme opposite in the phenomenology, in their appearance.

Narrator: And as it turns out, this material isn’t just useful for multimillion-dollar art projects. Scientists can also use it to reduce the glare in optical sensors, such as for telescopes that explore distant objects in space.

Wardle: You know, if you have a material that can absorb the stray starlight, then you can look further, and/or look in more detail, at objects such as exoplanets.

Narrator: But here’s the thing. As cool as this colour is, it likely won’t be the darkest for long. Because even an absorption rate this high still leaves some room for improvement. So keep your eyes peeled for the next colour that you can’t see.

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