Comment by cortic | Hacker News Reader

Comment by cortic | Hacker News Reader

I was really looking forward to reading this but its a bit of a disappointment.

First, green does not have the most energy of the visual spectrum, Blue, or more specific Violet does; https://socratic.org/questions/5348556b02bf347bedff8fed

Second the noise difference from 10% of the green would be negligible compared to the energy we are talking about. Also how does a plant regulate this 'noise'? The only logical explanation would be expand into the green in dark and out of it in light, but they have shown no mechanism for a plant to do that.

Sorry to say that after that fairly long winded article i have come to the conclusion we still don't know exactly why plants aren't all black.

Edit; Thinking about this more, maybe Chlorophyll a and Chlorophyll b take inverted wavelengths of light to produce a rectification effect..? Its interesting, but even if that were true, it would not explain the gap at green.

2nd Edit; I stand corrected, considerably more green light make it through the atmosphere thank you for the information spacemark.

>First, green does not have the most energy of the visual spectrum, Blue, or more specific Violet does

The article is correct. Blue photons have more energy, you're right. But more green photons are emitted by the sun, and even more reach the ground through the atmosphere than blue, so the total energy from green photons is significantly greater. Google blackbody spectrum.

https://en.wikipedia.org/wiki/File:Wiens_law.svg

https://lh3.googleusercontent.com/proxy/eDhfILMl70XZ-WUchpgo...

The "most energy" statement isn't about the frequency of light, it's about the power output of the sun, which peaks around green.

That power output really is the area under the curve, in which case most of the sun's energy is in the infrared, actually.

Sure. But the peak is around green, which is the point of the article and the answer to parent's question.

One theory is that yellow-green wavelengths don't pass through water as readily, hence ancestral sea-dwelling plants adapted to absorb red and blue wavelengths and that adaptation remains "good enough" for contemporary land plants.

Highly recommend the book "How the Earth Turned Green"

https://press.uchicago.edu/ucp/books/book/chicago/H/bo164656...

Not "good enough"! There are so many known instances where Evolution gets trapped in local maxima and can't escape it... Another local maxima that photosynthesis trapped itself is its efficiency being jumbled by higher O2 concentrations.

You do understand that this is a popular science article and that is reporting on this paper, right?

https://science.sciencemag.org/content/368/6498/1490

Did you conclude "we still don't know exactly why plants aren't all black" after reading the paper?

Thanks, looks like the full paper is for paid members only, but i will look into this further.

Well, nowadays there is a very convenient way of getting scientific papers: Sci-Hub. I guess everyone should decide for themselves if they want to use something like that or not.

I've skimmed the paper, its answered a lot of my questions. I think the article tried to dumb it down too much and skipped over some important information;

Still not sure why the absorption points couldn't be uniformly widened by nature, but i will go over the paper more thoroughly when time allows, its very interesting. thank you.

As a rule scientists are pretty smart and thorough and journalists, even if they understand the science, have to assume most people would be bored by too many details.

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