100 Are the Androids Dreaming Yet? X-rays The first Nobel Prize in Physics was awarded to Wilhelm Rontgen in 1901. He had discovered ‘X’ rays; so called because he had no better name for them. X-rays, as they became known, are just light of a very high frequency. Light comes in a variety of colors; at the low end of the frequency scale we see red, higher up blue and, at the top, violet. At this point human eyes give up and cannot see anything higher, so ultraviolet light is invisible to us. Bees, on the other hand, can see a long way into the ultraviolet spectrum and some flowers have beautiful ultraviolet markings that attract bees for pollination. Daylight contains a great deal of ultraviolet light which is wasted on us — other than to tan our skin. But all is not lost. Clever manufacturers put fluorescent dyes into their washing powders which stick to our clothes and convert ultraviolet into visible light, making our T-shirts look brighter as they reflect more visible light than fell on them. You can see this effect most easily in a disco when ultraviolet lights are shone on the dance floor and anyone wearing a newly washed T-shirt will glow bright white. The other common substance that fluoresces strongly on a dance floor is tonic water. Quinine, the active ingredient in tonic water, is a strongly : " f pee ~ 5 ; > A oy ‘ ih j, . ey A fe 4 Pe Flowers in Ultraviolet Light HOUSE_OVERSIGHT_015790