Hi. When we turn on a lamp in the room at night, the room gets bright. Now, is there such a thing that does the same thing but other way around? When, it's not night, i.e day, we turn the lamp on and it absorbs all the light in the room and make the room dark? I guess such a lamp would be similar to black hole, but it'd absorb, suck only lights. I hope I was not being ambigious this time.