Hold a candle in the dark and the curtain is yellow. Turn the lights on and the curtain is white. Some people insist that the candle shows the true color of the curtain no matter what you tell them. All scientific reasoning about light spectrum and frequency falls on deaf ears. They will begin to question the science and claim that the physics text books backing these calculations are funded by those with agendas and global control ambitions.
They will not understand the mathematics behind nanometres, electromagnetic frequencies, wavelengths etc and because the average person they are debating with does not have a physics degree and also lacks information needed, so they will simply claim that you don't know either so therefore my viewpoint about the curtains being yellow is fact until you are able to prove otherwise.
You cannot debate with someone over encumbered by
belief perseverance. You may try. You will not be successful in changing their minds.