^Title.
It is possible to thermally reduce carbon dioxide, but AFAIK the necessary electron transfer in photosynthesis cannot be thermally induced.
Sure, plants do it all the time. You just need a heat source that’s at about 6000 degrees.
but that heat source’s energy is not 6000 degrees once it reaches the plant
Sure it is. The spectrum of electromagnetic radiation coming from the sun matches that of a blackbody at 5000 degrees. Most notably, the peak of the spectrum is in the visible wavelengths of light - specifically, in the green wavelengths. Green plants don’t use green light for photosynthesis; they reflect it, which is why they appear green. Instead, they use red light. Which is to say that infrared wavelengths (the ones we most commonly associate with heat) are not useful for photosynthesis. But with a peak in the green band, sunlight has plenty of light in the red band, so plants do OK.
So a 200-degree space heater a couple of feet from your house plant in the basement won’t emit light in useful wavelengths and quantities. A 5000-degree ball of gas 93 million miles way will.
To make this explicit for our OP who might be a bit scientifically naive: “photosynthesis” refers to the specific chemical process used by Earth plants to consume electromagnetic radiation from the particular star called “the Sun” as seen from Earth’s distance and as filtered through Earth’s atmosphere. And that process won’t run on what you probably think of as “heat”.
Strictly speaking your question is ill-posed since “heat” describes something very different from “sunlight”. Those are not at all the same thing, or even different forms or flavors of the same thing. So they’re not in any sense alternatives for each other. What you asked is sort of like asking “Can a car run on kilograms instead of gasoline?” The answer of course is “Huh? Please ask a coherent question.”
A very different and possibly useful question is whether a different chemical process could be built using a different source of energy or a different spectrum of electromagnetic radiation to have the same inputs and outputs as does photosynthsis.
A reaction driven by radiation from a blackbody is still a photochemical process. The enzyme is not “using heat” any more than the ones under my LEDs are using semiconductors.
The radiation from a blackbody is in fact radiant heat, in every sense of the term.
And incidentally, there’s no particular relationship between heat and infrared specifically. Light of any wavelength can be produced by a hot object, depending on its temperature, and an object’s temperature will increase when it absorbs light of any wavelength. The only reason we associate heat with infrared specifically is that, for objects of the sorts of temperatures we’re familiar with, that’s what most of the radiation is. Get hotter, though, like the temperature of the Sun or of an arc welder, and you can produce visible light or ultraviolet in exactly the same way.
This is irrelevant for a single-photon photochemical excitation as per my last post.
No, it’s not, because the single photons are the manifestation of radiant heat energy.
And if you filter out the photos that will do the business, you can have all the radiant heat energy you want and not a whole lot of photosynthesis. What matters is what photos you’re getting. “Heat alone” as the OP asks, won’t do it.
No, if you filter out the photons, then you won’t have any radiant heat energy. The photons are the radiant heat energy.
Not all photons will trigger the reaction. You wrote that yourself earlier.
If you just filter out the wavelengths which are absorbed by chlorophyll, then what you have left is no longer a thermal distribution.
But it’s still heat.
I don’t have a cite for this, as I read it over 40 years ago:
In plants, increased heat increases the respiration rate. IIRC, every 10 degree C increase in heat doubles the respiration rate.
… that just goes along with the way the proteins prefer to work in the warm… about body temperature, 37 C…
Sure, plants are slower down at freezing and can grow faster with temperature… up to a point.
above warm, Of course, eg at 47 C, your “double” is well and truely decimated to “dead… never again!”… they die if its more than warm…
The OP was ruling out photons, if you read.
Anyway when you say that the photos are at 6000 C ? wrong , the only property of a photon is its frequency (or wavelength , or energy … as energy is directly proportional to frequency, just as wavelegth is inversely proportional!)… The shape of the spectrum barely matters, the “temperature” of a light source only indicates the peak frequency produced …Well it seems to promise its a ^ curve, but well maybe it isn’t ? Well anyway not all light is considered to be heat… While all of it can make heat, only the infrared part is labelled as heat.
Typical Dopers - The simple answer to the OP’s question is NO.
Put a plant into a room with no light and it will not photosynthesize. making it warmer will not help - make it warm enough and you will cook it.
That’s not heat. And as interpretations of the OP goes it’s not one I’d choose based on the phrasing.
The OP’s Q, strictly read, is bollocks. I said so way back up at post #6. Having said that …
I support bob++ as one plausible interpretation of the OP’s Q.
IMO, the only other plausible interpretation is “Can EMR from the IR spectrum only, containing zero light of wavelengths visible to humans, stimulate photosynthesis?” I suspect that’s the interpretation you (naiti) are supporting.
Assuming *arguendo *that interpretation …
Plants’ photosynthetic receptors are tuned to a slightly different band of wavelengths than human eyes. But we’re both tuned to generally the wavelength band of greatest solar emission as seen from the base of our atmosphere.
Looking here Photosynthesis - Wikipedia and specifically at the absorption spectra here Photosynthesis - Wikipedia we see that the effectiveness of both flavors of chlorophyll falls steeply to zero as we leave the visible reds for the IR.
Bottom line: The answer for that interpretation is also pretty much NO.
Bonus Q: Could different plants on a different planet under a different star have developed an analogous chemistry that works in what we Earthers call the IR spectrum? Possibly. Beyond my expertise to say. But I’ll bet 100 kwatloos that that’s not what the OP is asking.
Assuming s/he ever returns to read any of our (hah) wisdom.