Most People Can See the Polarization of Light

[ImaLooser]

In 1844 Wilhelm K. von Haidinger published a paper in Poggendorfs Annalen as to how to see the polarization of light. It appears as what is known as Haidinger's Brush and there is a graphic at Wikipedia. I've found the graphic is not quite accurate though. The yellow part looks like a sheaf of wheat tied at the middle, with the inividual stalks hanging out, and is shaped like an hourglass. That is, it looks like a double brush.

There are (at least) two ways to learn to see the brush. The natural style is at twilight to look at a cloudless portion of sky 90 degrees away from the Sun. I found that the trick is to NOT stare at one point. It is better to shift the gaze rapidly. If you are not concerned with being thought a lunatic spinning around is even better. The yellow portion will point at the Sun.

The modern style is to gaze at an LCD and tilt one's head back and forth. In the screen here before me the brush appears either vertically or horizontally, depending on whether my head is tilted left or right. In 1954 a William Shurcliff learned to distinguish left and right circular polarization in that the axes of the brush become skewed. Polarization is a quantum spin phenomenon, so in this case it is possible to see quantum spin. I never imagined neither did I dream of such a thing, but there it is.

 

[eljose79]

Thank you for bringing up the fascinating topic of Haidinger's Brush and the different ways to see polarization of light. I would like to provide some additional information and clarification on this subject.

Firstly, I would like to correct the statement that polarization is a quantum spin phenomenon. While it is true that the polarization of light is related to the spin of photons, it is not considered a quantum spin phenomenon. Instead, it is a classical wave phenomenon that can be explained using classical electromagnetism.

Furthermore, the phenomenon of Haidinger's Brush is not directly related to the polarization of light, but rather it is a visual effect caused by the interaction of polarized light with the human eye. The yellow hourglass shape that you described is actually an illusion created by the overlapping of two different images in the eye's retina. This is why the image appears double, as you have observed.

In terms of the two methods for seeing Haidinger's Brush, it is important to note that the natural method of looking at the sky at twilight is not recommended due to the potential damage to the eyes from staring at the Sun. The modern method of using an LCD screen is a safer alternative and also allows for the observation of left and right circular polarization, as mentioned by William Shurcliff.

In conclusion, while Haidinger's Brush is a fascinating visual effect, it is important to understand the underlying physics and to use safe methods for observing it. Thank you for bringing up this topic and I hope this information has been helpful.