A plant or even a tree search for the sun in nature that is both science and having studied the difference, also common sense.
We all know that the apical meristem will send down auxins that will diffuse to the dark side and stop the light side growing so that the plant bends towards the light, there's no argument there. If you put a dope seedling in a pot under a 2700K incandescent light bulb it will grow tall and spindly before falling over and dying. That's not what we want we want the plant to grow healthy and stretch.
Now as for the science of plants searching for the light, the 'science' that I've seen is that when a plant is under a canopy from other plants, the light will hit the other plants first and what filters through the leave is infrared wavelengths. This 'tells' the plant, i.e. is the signal for the plant to grow taller and get above the canopy.
This is the reason that many LEDs have 730nm wavelength LED. They don't throw off any light and they always have to tell you not to worry, they are not broken LED, it's just at the non visible part of the spectrum. That's the science.
All moving the light away does is give you less photons, but the photons you do get are the very same photons it would have got if the light was brighter, just less of them. Same effect would happen if you dimmed the light. So if you want dimmer light you're better off using a dimmer switch as it's the same effect as moving it further away, but would be cheaper. Moving the light away gives a better spread, that's the only real reason, unless too much heat is hitting the plant, OR, if you have super powerful lights, because anything over 1200 micro moles cannot be used without supplemental carbon dioxide, you'll just get leaf bleaching. But moving the lights further away, will not cause normal growth stretch.
I have 100%White 100%Blue and 100%Red, during late growth and I just knock the blue down to 50% in the week before the expected stretch. If you want stretchy plants give them more red, which makes sense because even though Red light has less energy than blue light, the plants make better use of the Red. They make the least use of green, only 25% as efficient as red, this is why "full spectrum" while light with heavy green, can give you a good par because green is in the PAR range but it's not as useful, as either the red or blue so a light with a lower par but a better spectrum can have a better PAR for all practical purposes. White LED's are the cheapest.
If I was not getting the stretch I wanted, then I'd look at the lights, if they didn't have 730mn I'd buy just that wavelength from ebay and make my own.