Birefringent thinking in a polarised world

Colour in a Polarised World

We are such anisotropic beings
Our neuronic lattices bifurcate our inputs
Rays of thought fast and slow right and wrong
Yet so isotropic, at least in self opinion,
such hubris
Rejecting our double refractions despite their logic
In favour of the certainty of total extinction
Wishing to be as solid as a garnet,
as opaque as a pyrite
living in wilful ignorance of our birefringence.

The Science

Light is refracted [1,2,3] as it passes from one material to another. In anisotropic [3,5] minerals light refracts into two rays (double-refraction [6]), each polarised [4] at right angles to the other and travelling at different velocities. This is called birefingence [1,2,3,4,5,6].

In petrological microscopy [7], polarised light [4] is double-refracted [6] through anisotropic [5] minerals and polarised again. The resultant rays interfere with one another, producing interference colours [7]. These thickness-dependent colours are correlated with the mineral’s birefringence, as shown in a Michel-Levy chart [7], allowing for mineral identification and a deeper study of rock mineralogy. Geology students spend many hours immersed in this hidden, colourful world!

[1]       https://en.wikipedia.org/wiki/Refraction

[2]       https://en.wikipedia.org/wiki/Refractive_index

[3]       https://en.wikipedia.org/wiki/Isotropy

[4]       https://en.wikipedia.org/wiki/Polarization_(waves)

[5]       https://en.wikipedia.org/wiki/Anisotropy

[6]       https://en.wikipedia.org/wiki/Birefringence

[7]       https://www.microscopyu.com/techniques/polarized-light/principles-of-birefringence

The Theme

Without a petrological microscope, rock thin-sections are mostly shades of grey. Likewise, our ability to ‘see’ other’s opinions resides with how we investigate them.  In this work, colours are metaphors for opinions refracted within our minds. Do we double-refract the information to see both sides of the story?

The faux-thin-section image is reflected in the viewers eye, a small image with a big impact on the mind, just like ideas. The Michel-Levy chart [7] background hints at the range of possibilities. The ‘rhombic’ text echoes the extreme birefringence seen in calcite [6]. It speaks about a world of extreme opinions, reducing conversation to a double-refracted babble.

The circular image was created using cellotape on a plastic film (not an actual rock thin-section), the polarised light from a computer monitor and a sheet of Polaroid film. This image was captured by a Nikon D40x SLR. The artist’s eye was captured selfie-style using a Pixel 7 camera. The colourful background is based on the birefringent colours displayed in a Michel-Levy chart while excluding the important graphical elements of the chart for the purposes of the art. All images were processed, manipulated and combined using Affinity and Paint Shop Pro software with no AI assistance.

The Artist

Greg McNamara (he/him) is an Australian geologist and geoscience educator with specialist interests in sedimentology and vertebrate palaeontology. His interest in science is eclectic and he enjoys teaching science at all levels.