Just stop a minute and think about it

Originally published 18 July 1994

Some­times it’s fun to think about things that no one has thought about before.

Some things are thought about for the first time because they require a mea­sure of genius. For exam­ple: Dar­win think­ing about evo­lu­tion by nat­ur­al selec­tion, Ein­stein think­ing about rel­a­tiv­i­ty, or Wat­son and Crick think­ing about the DNA dou­ble helix. Being the first to think about these sorts of things can win you a Nobel prize.

Oth­er things are thought about for the first time because they are so utter­ly com­mon­place that no one has both­ered to think about them. These are the kind of things I like to think about.

If I’ve learned any­thing in my fifty-odd years of think­ing about com­mon­place things, it is that the com­mon­place can be miraculous.

When you think about it, I mean.

Con­sid­er starlight.

I was look­ing at Arc­turus the oth­er night. Arc­turus is 36 light-years away. That’s 216 tril­lion miles. And I saw it.

It’s not like a spe­cial ray of light came from Arc­turus to my eyes. That’s what we often imag­ine. We’ve seen so many pic­tures of Stars of Beth­le­hem and Twin­kle Twin­kle Lit­tle Stars with beams of light shoot­ing straight down to Earth that it’s easy to believe that starlight is some­how direct­ed towards us. But, of course, when we think about it, we real­ize that this is not so.

The light from a star goes out in every direc­tion, like a con­stant­ly expand­ing bal­loon of ener­gy, get­ting weak­er all the time. Only the tini­est frac­tion of a star’s light falls upon the Earth.

How much? Let’s do the cal­cu­la­tion. Don’t be put off by the num­bers; just wait for the bot­tom line.

At a dis­tance of 216 tril­lion miles, the light of Arc­turus is spread out over a sphere with an area of 586,000,000,000,000,000,000,000,000,000 square miles. The Earth has a cross-sec­tion­al area of about 50 mil­lion square miles. So the frac­tion of Arc­turus’ light that falls upon the Earth is about 1 part out of 10 sex­til­lions. That’s 1 fol­lowed by 22 zeros.

Of the starlight that falls on Earth, an even tinier frac­tion enters the pupil of my eye to form an image of the star. Anoth­er cal­cu­la­tion: How does the area of my pupil com­pare to the cross- sec­tion­al area of the Earth? I’ll spare you the details. Click, click, click on the cal­cu­la­tor. Anoth­er fac­tor of 10,000,000,000,000,000,000, more or less.

So the frac­tion of Arc­turus’ light that enters my eye is one part out of 100,000,000,000,000,000,000,000,000,000,000,000,000,000.

Get­ting bored? Stick with me.

Let’s see if I can give you a sense of what this num­ber means. The oceans of the Earth con­tain about 320 mil­lion cubic miles of water. If you dipped the point of a pen­cil into the ocean, the amount of water you’d come up with, com­pared to all the waters of the oceans, is more than the frac­tion of Arc­turus’ light that enters my eye.

You see what I mean. There’s noth­ing ter­ri­bly pro­found about these cal­cu­la­tions. A lit­tle high-school sci­ence and a cal­cu­la­tor is all it takes. So why think about it at all?

If I’ve learned any­thing in my fifty-odd years of think­ing about com­mon­place things, it is that the com­mon­place can be miraculous.

Well, think about it. All those expand­ing spheres of light from thou­sands of stars (the ones that are bright enough to see), mush­ing about through space, falling upon the pupils of our eyes, many of them from only slight­ly dif­fer­ent direc­tions, and out of a damp pen­cil-tip’s worth of light our brains form an image of Arc­turus. And Rigel. And Betel­geuse. And…

And that’s just the brighter stars. If we con­sid­er the most dis­tant star we can see with the naked eye, which would be rough­ly 10,000 light-years away, then we get anoth­er fac­tor of…

Stop! This has gone on long enough. We’re over­dos­ing on num­bers. Let the poets, artists, and musi­cians have a go at describ­ing the stars.

Shake­speare’s “night’s candles.”

Hop­kins’ “fire folk sit­ting in the air,” or, bet­ter, his “dim woods quick with dia­mond wells; the elf eyes.”

Or Van Gogh’s “Star­ry Night Over the Rhône,” those fiery vor­tices, those furi­ous whirlpools of light.

Or Hayd­n’s “Cre­ation,” prob­a­bly inspired by a view of the stars through astronomer William Her­schel’s tele­scope in 1792, the orches­tra ascend­ing a lumi­nous crescen­do of sound, “the space immense of th’ azure sky, a count­less host of radi­ant orbs adorn.”

Bal­loons of starlight inflat­ing across tens of tril­lions of miles to be sam­pled by our eyes. Damp pen­cil-tips of ener­gy, but enough to excite the reti­na, sig­nal the brain, open our minds to the uni­verse, inspire, fright­en, ele­vate, surprise.

Utter­ly com­mon­place. But when you think about it — miraculous.