The robin: the latest in quantum computing

There is good evidence to suggest that animals are equipped with senses unfamiliar to us humans. These senses detect heat, the polarisation of light, electricity and the Earth's magnetic field. Quite how they do so is another matter. In the case of the magnetism, the latest research suggests a quite fascinating mechanism. To put it very briefly, chemicals in the robin's eye react to light in such a way that, when they have been 'energised' by the light, they become sensitive to the Earth's magnetic field. So, by seeing light, they also see the magnetic field.

In a bit more detail - and it is here that it gets fascinating and weird - it appears that these chemicals exploit the strange phenomenon of quantum entanglement. A way to grasp the strangeness is the following. Imagine two identical balls, the top halves painted red, the bottom blue. Imagine them fixed in separate wooden boxes with an axle through the middle and spinning constantly. As you look into the box, you see red, then blue, then red, then blue, and so on. Now imagine that these two balls are set spinning and the boxes are shut (we'll not worry about how they keep spinning.) Next, suppose that by opening the box, you stop the ball rotating and see either the top red half or the bottom blue half. Finally, the two boxes are carried off in opposite directions until they are a long way away from one another.

Now for the strange bit. The moment one box is opened, the ball stops and you see red or blue, as I said above. But at the very same instant, the ball in the other box stops rotating and shows the opposite colour. What's odd is that this can happen when they are separated by any distance. Yet it is supposed to be the case that information cannot travel faster than the speed of light. The two balls are 'entangled'. They are somehow connected so that any changes to one immediately bring about changes to the other.

The claim, then, is that photons of light that activate special chemicals in the eye affect electrons in the chemicals that exist in a state of quantum entanglement, the effect of which is that they are differentially affected by the Earth's magnetic field, from which further reactions could be caused leading to a complex sensitivity to the field. Bizarre and fascinating. More details here.