Comment by michaelmrose
18 hours ago
They actually are 380-750nm is the visible range. That said one lumen is approx 3.8×1015 photons and an LED bulb produces 75-110 lumens per watt. It seems like the original poster meant that we are not capable of detecting this with the naked eye even though it is theoretically in the right range.
https://physics.stackexchange.com/questions/880/how-many-pho...
https://www.voltlighting.com/learn/lumens-to-watts-conversio...
Humans are able to see single photons, so your (and others') arguments don't hold substance.
I can turn out the light and not see my hand emitting light. Either a single photon isnt enough to be perceptible on average in real environments or something else is defective about the assumption for instance intervening tissue absorbing most or all photons involved.