more challenges in penetration right our intuition tells us light will not penetrate through tissue because we can't even see through our own palm right so when we close our eyes our eyelids is going to block all the light we can't even see the outside but you will actually see light right this is why some people when they sleep they have to wear blindfolds you have to wear blindfolds our eyelids are not dark enough they're not blocking enough light right so photons you know basically it's a quantum term for light photons will