Exactly, energy cannot be destroyed, so all energy eventually turns in heat.....and the amount of absorption is extremely inefficient (1-3% of light)so it can safely be ignored....1000w hps = 1000w led.
If you think a light that's 10% effiecent makes 90% heat you are completely ass backwards, 100% of all light turns to heat.
E=mc^2 is not about that's it's about the increased relative mass of a body times the speed of light squared....it has nothing at all to do with grow lights....i really advise you going and picking up a good book on physics you really do not know what you are talking about.
If you still have difficulty grasping this concept i'd advise reading this thread
https://www.rollitup.org/t/heat-from-1200w-of-1212s-vero-29s-cxm-22-cxb3590-compared-to-2x-600w.936071/
Here's some good quotes from other members
All energy does NOT turn into heat.
If a light is 10% efficienct then that means that it only converts 10% of the energy that it uses into light. Whether the remaining 90% is expelled as heat depends on the way the light works, is it moving perhaps? Is some energy being used up to move it? Otherwise yes, if there's nothing extra to the light a 10% efficiency is going to mean that 90% of the energy consumed is not converted into light and will typically be observed as heat.
E=mc^2
is literally..
(Energy) equals (mass) times (the speed of light constant ~300 million) squared.
That's why atomic bombs are so violent though they are relatively small in mass, comparatively. This is because some mass of the core during the reaction is converted into light, heat, ect, and at an incredible rate (~300,000,000^2).
NOT all energy turns to heat. A speaker that moves from an amount of kinetic energy will not have that same amount of energy go into making heat because it's already been used to move the object (speaker). There may be resulting friction from that movement but the energy used to move the speaker can't be used twice, one time to move the speaker, and then also again to heat the speaker. You can't create energy out of nowhere.
I think we're on the same page although your a little bit off on your reasoning and explanation. The point of using LED over HPS is because they are more efficient and have less thermal runoff (more efficient, more ppfd/w, more lm/w, less heat/w), thus why you'd use LED if you were trying to cut heat while keeping PPFD unchanged.
I studied thermodynamics in college as per the general required curriculum for Engineering majors. If you don't understand the laws of thermodynamics that's ok, and I really shouldn't have replied, but I did out of a little engineering pride, and to that end I'm not trying to be confrontational I just know this stuff on a professional level.
LEDs and HPS produce light via different methods. Thus the difference in efficiency, which directly correlates to thermal runoff. The higher the efficiency the cooler the tech.
https://en.m.wikipedia.org/wiki/Mass–energy_equivalence
**scroll down to the "Efficiency" sub heading...
