Understanding Vantablack, the blackest material ever made
Light-trapping carbon nanotubes are the secret ingredient in the ultrablack material, writes Jake Port.
The futuristic, eye-wrenching Vantablack coating is billed as “blacker than black”, and it lives up to the claim. The light-eating material can make you doubt your perceptions of what you’re looking at: solid, three-dimensional objects suddenly appear to become flat voids, holes in the spacetime continuum. Black holes are probably blacker, but not by much.
How does it work? Developed by English company Surrey NanoSystems, Vantablack uses nanotechnology to absorb more than 99.965% of the visible light that reaches its surface. It’s hard to be more precise than that because the amount of light reflected is too small to detect.
The name comes from what makes the material work: a Vertically Aligned NanoTube Array. The coating is constructed from a ‘forest’ of equally spaced carbon nanotubes that allow light to enter between their trunks but not escape. Instead, the particles of light (photons) bounce around the nanotube array, dissipating their energy as heat. Because 99% of the material is empty space, a square metre of the coating only weighs around 2.5 grams.
Being the darkest material ever developed is not just a party trick: Vantablack has any number of uses in optical applications. One of the more exotic is in telescopes that hunt exoplanets, where it can absorb starlight that normally hides the planets’ presence.