Notes from Professor Boggs:
Light is obviously a huge subject to tackle in a song! After grasping at and rejecting several concept “angles” I finally chose to focus on visible light and how we see, while branching off to some side topics (other EM spectrum, particle/wave) towards the end. This song is a great lead-in to an optics lab, especially one involving combining of filtered light.
Your more computer-inclined students will be interested in the RGB color model tie-in. You can also, if you wish, explore the “subtractive” color model used for ink printing: CMYK (cyan the “red absorber”, magenta the “green absorber”, yellow the “blue absorber” and “K” pure black).
If this is the first exposure to wave-particle duality, it should probably be mentioned but left alone for future exploration (unless you happen to have one of THOSE students).
Like a wave upon the ocean
Like ripples on the sea
From a source in all directions
Bouncing off to make reflections
Like the shining moon
In a million undulations
In a song of many tones
Brings a wealth of information
We see only three vibrations
Red, green and blue
Oh, light can vibrate fast or slow
Its energy is high or low
But of those million frequencies
Our eyes are only built to see
Red, green and blue
Mixes these three waves together
Shines upon our colored earth
Drink the red and blue from sunshine
Bounce the green back in a straight line
To my waiting eye
On a brilliant summer blue day
Even air will drink the light
Scatters forth in all directions
Making blue the sky’s complexion
With a yellow sun
Green and red make yellow
Green and blue, cyan
Red and blue, magenta
All the colors can come from
Red, green, and blue
Gamma, X-ray, ultraviolet
Infrared and microwave
Cannot show us all the spectrum
But our instruments detect them
All across the sky
In the wondrous ways of wavelength
It’s emitted and absorbed
From the dancing of electrons
Giving birth to streams of photons
Little sparks of light
Oh, light’s a particle, a wave
a mystery how it behaves
and how it carries energy
to light our world and let us see
red, green and blue…
Light – or more generally, electromagnetic waves – is one of our greatest mysteries, as well as our greatest source of information about the whole universe! Most of the time, it’s useful to imagine light as a vibrating “wave” spreading out in an expanding sphere from its source.
When light hits something “reflective” it can bounce off, just like water waves bouncing off a sea-wall. Most of what we “see”, like the moon, is reflected light.
Waves have frequency, the speed of the ripples. Faster vibrations (higher frequencies) carry more energy. Light comes in billions of different frequencies (or wavelengths, two ways of talking about the same thing).
How many of these wavelengths do we human beings see? Three! We call them Red, Green, and Blue light, and those frequencies trigger the “cones” in our eye’s retina. Their wavelengths are tiny, over 200 of their ripples could fit in the width of a human hair. But there are lots of waves even tinier that we can’t see!