How Birds of Paradise Produce Super-Black Feathers | Hacker News Reader

How Birds of Paradise Produce Super-Black Feathers

theatlantic.com

96 pointscurtis19 comments

That's very interesting, because at 99.95% absorption it has slightly worse performances than Vantablack (99.96%) but much better performances than Vantablack S-VIS (99.8%), the "low-temperature"[0] sprayable version.

Furthermore studying BoP structures could provide for significant mechanical resistance improvements over Vantablack, which has good resistance to mechanical vibration (no issue putting it on top of a rocket) but pretty much none to contact/abrasion (Surrey's website clearly states that a vantablack-coated surface "needs to be protected from accidental touching, for example behind or inside a component, or situated where contact is avoided" and that it is "highly susceptible to any direct impact or abrasion").

OTOH the article states that the absorption is very variable with angle but does not provide any numbers, that would be interesting (according to Surrey Nanosystems, S-VIS still provides 99.4% absorption at 70˚ VIS, they don't provide any hard number for Vantablack).

[0] ~100C versus ~450C for the original Vantablack)

I sorta love it when mother nature comes close to or beats man-made things. Birds of Paradise.. super black... the world is truly amazing.

Gotta love bionics!

https://en.wikipedia.org/wiki/Bionics

Really great video by BBC. The little dance that bird does when fending off other birds is really amusing, the movements and symmetry of wings positions is something that is an art in itself.

Up until now, I had assumed that BBS Planet Earth scene was just some enhanced photography at work.

https://www.youtube.com/watch?v=W7QZnwKqopo

Even now, it still seems pretty unreal.

I’m glad to learn it’s not manipulated footage, adjusted by what seemed like possibly the choice to film during overcast weather, with possibly some less-than-natural lighting and carefully selected camera angles.

> Animal eyes and brains are wired to control for the amount of ambient light. That’s why an apple looks red whether it is in the sun or the shade, even though the wavelength hitting our eyes is quite different in those scenarios.

It's not obvious to me why the wavelength should be different when an apple is viewed in direct sunlight vs indirect sunlight (shade). Dimmer, lower amplitude, but different wavelength?

Maybe with less direct light, more of the light is made up of light reflected from surroundings, which quite likely has a different spectral power distribution than direct sunlight.

E.g. many shadows are blue-tinted because they are lit by the non-sun parts of the sky which are blue because Rayleigh scattering is stronger at short wavelengths.

There's also polarization to throw in the mix. Usually photographers will use a circular polarizer to remove reflections(say from water) while keeping much of the diffuse lighting intact.

> It's not obvious to me why the wavelength should be different when an apple is viewed in direct sunlight vs indirect sunlight (shade).

Assuming all light is sourced from the sun, “shade” means the direct light is blocked and all light hitting the object is reflected from other objects. In most cases, that will mean that the incoming mix of wavelengths is different based on what objects in the environment reflect and where they are positioned and how they are lit (direct sun or shade, which makes this recursive). The difference in incoming mix of wavelengths will, for an object that doesn't reflect only a single wavelength, tend to result in a change in the relative intensities in the mix of outgoing wavelengths, which (if color perception didn't correct for illumination) will change the apparent color.

And color perception doesn't completely correct for illumination, though it's usually good enough to associate the same object in daylight vs. shade; this lack of full correction is why lighting tricks can be used to create fairly radical changes in appearance. But those involve combinationsn of lighting differences and illuminated material that aren't common in nature, for the most part.

But they are speaking of "the wavelength", i.e. they assume there is only a single wavelength. Your explanation throws away that simplifying assumption.

“There’s something about this that’s so black, it’s like how much more black could this be? And the answer is none. None more black.”

They do produce mana of any color though.

Went to make this joke and happy someone beat me to it.

No mention of black velvet in the article -- which is famously difficult for photographers to capture because its so black. I wonder if there is a similar effect at play.

My main thought after reading this article was "how can I get a shirt that's this black?"

I'm probably vain enough that I'd get along well as a bird of paradise.

Can we use this concept to make solar panels more efficient? Why are solar cells that dark blue color and not black? Shouldn't they absorb all of the light?

I believe solar cells only get electrical energy from photons with energy roughly corresponding to the bandgap of the cell.

Does its spectrum conform to the theory of black body radiation?

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