In praise of argon

Harlow Shapley's Beyond the Observatory provides a fun thought exercise with argon.

Most of the "other" is actually argon, an inert gas.  Find some basic information about argon here.  But let's face it, argon in and of itself is pretty boring.  It's a noble gas*, meaning it thinks it's too good to react with anything else.  In fact, argon is so inert, its name comes from the Greek word meaning inactive.  So it's just been meandering around Earth's atmosphere since the Earth had an atmosphere--about five billion years, give or take.  The total amount increases slowly but steadily: it's a biproduct of the radioactive decay of a potassium isotope in some rocks.

Despite it making up only 1% of the atmosphere, with each breath, Shapley calculates that we inhale and exhale around 3x10^19 (30,000,000,000,000,000,000) argon atoms.  These atoms get diffused throughout the atmosphere in the subsequent minutes, days, and months.  He further supposes that the breath you take a year from now includes at least 15 of the exact same atoms.  Since these atoms don't react with you, or anyone else, we see an interesting implication.  You're sharing your breath with everyone else.

Shapley theorizes that with each breath, you take in 400,000 argon atoms that Gandhi breathed during his life.  You also share the same argon used by Shakespeare, Hitler, and dinosaurs (although there's a lot of new argon since then, too).  He writes:

We have argon from the sighs and pledges of ancients lovers, from the battle cries at Waterloo, even from last year's argonic output by the writer of these lines, who personally has had already more than 300 million breathing experiences.

Harlow Shapley is generally credited with the first understanding of the shape and scale of the Milky Way, and recognizing our solar system's location in it.  His obituary, as it appeared in Nature in 1972, is reprinted here.


The image above, and more information about Earth's atmosphere, is located at http://liftoff.msfc.nasa.gov/academy/space/atmosphere.html.
*From Hawley's Condensed Chemical Dictionary, "In chemical terminology, this term describes an element that either is completely unreactive or reacts only to a limited extent with other elements." 

Posted at 09:48AM May 17, 2006 by WILSON, JOSHUA in Thought experiments  |  Comments[2]