A Place Under A Rainbow

Somewhere over the rainbow, way up high
And the dreams that you dream of, once in a lullaby
Somewhere over the rainbow, blue birds fly
And the dreams that you dream of, dreams really do come true

Someday I'll wish upon a star
Wake up where the clouds are far behind me.
Where trouble melts like lemon drops,
High above the chimney top,
That's where you'll find me.

Somewhere over the rainbow, bluebirds fly
And the dream that you dare to
Why, oh why can't I?

            Lyrics by Yip Harburg

ROYGBIV or Roy G. Biv is an acronym for the sequence of colors commonly described as making up a rainbow: red, orange, yellow, green, blue, indigo and violet. A rainbow spans a continuous spectrum of colors; the specific bands are an artifact of human color vision.

In 2003, I took a class at OSU entitled “Holography I”.  It was a fascinating cross-listed course between Art and Physics that allowed the students to understand and create several types of holograms.  My creations were poor at best, but I was exposed to the world of wavelengths.  I learned that visible light from the sun is actually composed of the colors of the rainbow that can become distinguishable when sunlight passes through a prism.  I learned that light travels through waves with properties of wavelength and frequency.  Wavelength is the distance between identical locations on adjacent waves.  See illustration below (https://imagine.gsfc.nasa.gov/educators/lessons/roygbiv/).

Frequency is the number of complete wavelengths that pass a given point each second.  All light travels at the same speed, but each color has a different wavelength and frequency.  It is the different wavelengths that cause the different colors of light to separate and become visible when passing through a prism.

The typical human eye is only capable of perceiving wavelengths between 390 and 750 nanometers.  A nanometer is a billionth of a meter.

To the Rainbow

Triumphal arch, that fill'st the sky
When storms prepare to part,
I ask not proud Philosophy
To teach me what thou art; -

Still seem; as to my childhood's sight,
A midway station given
For happy spirits to alight
Betwixt the earth and heaven.

Can all that Optics teach unfold
Thy form to please me so,
As when I dreamt of gems and gold
Hid in thy radiant bow?

When Science from Creation's face
Enchantment's veil withdraws,
What lovely visions yield their place
To cold material laws!

And yet, fair bow, no fabling dreams,
But words of the Most High,
Have told why first thy robe of beams
Was woven in the sky.

When o'er the green, undeluged earth
Heaven's covenant thou didst shine,
How came the world's gray fathers forth
To watch thy sacred sign!

And when its yellow luster smiled
O'er mountains yet untrod,
Each mother held aloft her child
To bless the bow of God.

Methinks, thy jubilee to keep,
The first-made anthem rang
On earth, delivered from the deep,
And the first poet sang.

Nor ever shall the Muse's eye
Unraptured greet thy beam;
Theme of primeval prophecy,
Be still the prophet's theme!

The earth to thee her incense yields,
The lark thy welcome sings,
When, glittering in the freshened fields,
The snowy mushroom springs.

How glorious is thy girdle, cast
O'er mountain, tower, and town,
Or mirrored in the ocean vast,
A thousand fathoms down!

As fresh in yon horizon dark,
As young thy beauties seem,
As when the eagle from the ark
First sported in thy beam:

For, faithful to its sacred page,
Heaven still rebuilds thy span;
Nor lets the type grow pale with age,
That first spoke peace to man.

            Thomas Campbell (1777-1844)

CPW