Juliette McGregor in Discover:
Ever fancied having a superpower? Something you can call upon when you need it, to hand you extra information about the world? OK, it’s not X-ray vision, but your eyes do have abilities that you might not be aware of. We are all familiar with color and brightness, but there is a third property of light: “polarization,” which tells us the orientation in which light waves are oscillating. Animals, like bees and ants, use the polarization patterns in the sky as a navigation aid. But few people, even in the scientific community, are aware that humans can sense the polarization of light with the naked eye. In research we’ve just published in Proceedings of the Royal Society B, we used an experiment that was originally designed to test the visual abilities of octopuses and cuttlefish to investigate our human ability to perceive this polarized light.
Imagine a jump rope is a light wave traveling through space. If you move the rope from side to side, the wave you make is horizontally polarized. But if you shake it up and down you create a vertically polarized wave. Generally, light is a mixture of polarizations, but sometimes – for example in parts of the sky, on your computer screen and in reflections from water or glass – a large percentage of the waves are oscillating in the same orientation. This light is described as being strongly polarized.