From my experience, fire infrared light can be stronger than the sun. I used to

have occasional pain in my left knee, but resolved it by one or two really hot

sessions at the chimney(I nearly burned myself lol so it has to be really hot in

order to get rid of chronical pain). Knee pain is gone now. I have read a theory

of the vagus nerve sending harmful substances produced by the microbiome in the

bowels to the knee to prevent it going to the brain. The useful compounds get

teleported to the brain(we got no clue how the vagus nerve does it, but if you

lack a functioning vagus nerve the transportation ceases).