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>like visible light,, infrared light gets stopped almost completely by skin Actually light passes through skin rather easily. You can test this by putting a fl
by mike00632 7y ago
>like visible light,, infrared light gets stopped almost completely by skin
Actually light passes through skin rather easily. You can test this by putting a flashlight up to your hand. Light even acts as a catalyst for nutrients in your body according to some recent studies:
https://www.ncbi.nlm.nih.gov/pubmed/24198392 https://www.ncbi.nlm.nih.gov/pubmed/24198392
- knzhou 7y agoMaybe a fraction can pass through the scalp, but what about the skull?
- throwaway_law 7y agoquantum tunneling
- rubicon33 7y agoSeriously, why is nobody else asking THIS question. I'm usually convinced there are a ton of really smart people on HN... much smarter than myself. Yet, this thread is one of those few times where I'm found doubting. Either I am just totally missing the facts here, or yea... there's some wild placebo + self convincing going on.
- manmal 7y agoYou are missing facts indeed, see my sibling comment.
- manmal 7y agoNear infrared light is of lower frequency than visible light, so it can penetrate matter more easily. UV light barely passes through more than a few layers of skin cells (thereby potentially overloading those cells with a lot of energy, causing DNA damage), while visible light can go millimeters deep, and near infrared can go even deeper. Near infrared can be used to measure bone density. This would not work if bone were fully opaque to IR light.