This is Rima again, your friendly white antelope.
I have this daily (weekday) routine of watching this YouTube variety-talk-show-comedy-esque series called “Good Mythical Morning”, or endearingly known as GMM (Where my mythical beasts at? No? Me only? Okay never mind.), hosted by long-time BFFs Rhett and Link (I can get into their whole life story but that’s for another day).
One of their recent episodes (dated March 15, 2017) titled “Trying the Instagram Rainbow Trend” intrigued me (all their episodes intrigue me but this one more so because science). Click on the video below to watch the full episode.
Apparently, there is a recent trend on Instagram where people are “using the refraction of light to create these beautiful technicoloured effects”, according to the article from Glamour Magazine titled “How to create a rainbow light filter: the ultra pretty trend taking Instagram by storm” (link: Glamour Magazine – How to create a rainbow light filter) which the GMM episode was based on.
Screenshot of the GMM episode, showing an example of the trend
Of course the guys tried this trend and decided to call it #rainwhoa.
Screenshot of the GMM episode, Rhett and Link attempting the #rainwhoa, calling this one the Rain Bros.
I kind of chuckled to myself, because
1. I never really understand how trends catch on on social media because it seems like everything can be a trend,
2. This is simple science.
(To be honest, my fascination of colours and light got me into physics, so writing about this is really exciting for me.)
The visible spectrum
There are seven main regions in the electromagnetic spectrum, which is a spectrum of electromagnetic waves with different wavelengths and frequencies, and the visible spectrum is one such region. Our eyes will respond to a certain range of wavelengths and the wavelengths of the visible spectrum fit that range.
Many of us probably memorised the order of the spectrum (or commonly known as the rainbow): Red, Orange, Yellow, Green, Blue, Indigo and Violet. They are arranged as such precisely because of their wavelengths. Red has the largest wavelength and violet has the smallest.
Spectral colours. Image from: http://aty.sdsu.edu/explain/colors.html
Dispersing light through a prism
If you have ever heard of the English band, Pink Floyd, you would have probably seen the cover of one of their albums, The Dark Side of the Moon. I bring this up because not only is it artistic (you can read the designer’s thoughts in this Rolling Stone Interview: Storm Thorgerson: How I Designed the Cover of ‘Dark Side of the Moon’) but it has a scientific truth to it.
Pink Floyd’s the Dark Side of the Moon album cover. Image from https://www.discogs.com/Pink-Floyd-The-Dark-Side-Of-The-Moon/release/1873013
Shown on the album cover is a stream of white light being shone on a prism, resulting in the dispersion of the visible spectrum.
A prism is one of the more common ways of dispersing white light into its constituent colours (try making a colour wheel with all the seven colours and spin that wheel. You will eventually see the wheel turn white).
When light enters the prism, its speed slows down, as the prism is optically more dense than air. (You can think of this as driving a car from an expressway to a one-lane street; your speed slows down.) This phenomenon is known as refraction. This causes the light to bend, and since the different colours have different wavelengths, they bend at different angles. The smaller the wavelength of the colour, the slower it travels, and so the more it bends.
A triangular prism dispersing white light, animated, adapted from Wikipedia. By Lucas V. Barbosa – Own work, Public Domain, Link
This is why when you look at dispersion pictures, like the one in the Dark Side of the Moon album cover, you see that the red light is ‘on top’ (because it bends less) and the violet light is ‘below’.
If you wanna keep up with the trend, go get yourself a triangular prism! It goes as cheap as a few dollars. You can get yours at Lazada (Buy Triangular Prism from Lazada).
Again, this is not a paid endorsement of this product.
So friends, be inspired by the beauty of science, and who knows, you might be the creator of the next social media trend (hopefully not the ridiculous ones).