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> Green light has too many peaks and valleys and can overload the photosynthesis systems so they reflect a lot of it. This doesn’t make any sense to me. Why wo

> Green light has too many peaks and valleys and can overload the photosynthesis systems so they reflect a lot of it. This doesn’t make any sense to me. Why would peaks and valleys overload something? Why would green light have more peaks and valleys? I was a bit sloppy with the way I phrased that—what I really meant was “the reason why plants use specific quanta of light is the same reason why photovoltaics absorb specific quanta of light” but I didn’t put much thought into how worded it. Plants absorb light near two different spectral peaks. This is not entirely dissimilar to the idea of a multijunction photovoltaic cell. The color of light between the two peaks is green.

Armisael16 6y ago
I don’t know if this is what the previous poster was getting at, some there is some theoretical evidence that the absorption wavelengths used in photosynthesis are not tuned for maximum power input but for stable power input: https://arxiv.org/abs/1912.12281 https://arxiv.org/abs/1912.12281 If this is the case it would be a motivation that is fundamentally very different than that of a multijunction solar cell.
- klodolph 6y ago
  I've read that paper, I didn't realize the comment was referring to that. > If this is the case it would be a motivation that is fundamentally very different than that of a multijunction solar cell. Solar cells are designed by humans with human motivations, and plants are "designed" by evolutionary processes which lack motivation entirely. Yet, in spite of this, there are astonishing similarities between the limitations of solar cells and the limitations of plants. Isn't that fascinating, that processes with such disparate origins have such similarities?
  - Armisael16 6y ago
    I don’t see any meaningful similarities beyond ‘they absorb light at more than one frequency’. It doesn’t seem particularly fascinating to me; it’s patently obvious that if you absorb at two frequencies you should absorb at two different frequencies.
    - klodolph 6y ago
      > I don’t see any meaningful similarities beyond ‘they absorb light at more than one frequency’. Ah, that's definitely not what I'm talking about. Look at the relationship between efficiency and wavelength for plants and photovoltaics... the similarity is clear. Both photovoltaics and plants are capable of absorbing specific amounts of energy from incoming photons but not other amounts. Any excess energy becomes waste heat. The reason is because in both systems, the incoming light is used to move electrons from one state to another; the energy required to do this must usually come from one photon. Not all solar power systems work this way.

Armisael16 6y ago

I don’t know if this is what the previous poster was getting at, some there is some theoretical evidence that the absorption wavelengths used in photosynthesis are not tuned for maximum power input but for stable power input: https://arxiv.org/abs/1912.12281 https://arxiv.org/abs/1912.12281 If this is the case it would be a motivation that is fundamentally very different than that of a multijunction solar cell.

klodolph 6y ago
I've read that paper, I didn't realize the comment was referring to that. > If this is the case it would be a motivation that is fundamentally very different than that of a multijunction solar cell. Solar cells are designed by humans with human motivations, and plants are "designed" by evolutionary processes which lack motivation entirely. Yet, in spite of this, there are astonishing similarities between the limitations of solar cells and the limitations of plants. Isn't that fascinating, that processes with such disparate origins have such similarities?
- Armisael16 6y ago
  I don’t see any meaningful similarities beyond ‘they absorb light at more than one frequency’. It doesn’t seem particularly fascinating to me; it’s patently obvious that if you absorb at two frequencies you should absorb at two different frequencies.
  - klodolph 6y ago
    > I don’t see any meaningful similarities beyond ‘they absorb light at more than one frequency’. Ah, that's definitely not what I'm talking about. Look at the relationship between efficiency and wavelength for plants and photovoltaics... the similarity is clear. Both photovoltaics and plants are capable of absorbing specific amounts of energy from incoming photons but not other amounts. Any excess energy becomes waste heat. The reason is because in both systems, the incoming light is used to move electrons from one state to another; the energy required to do this must usually come from one photon. Not all solar power systems work this way.