This column was first published in The Tablet in June, 2006, and re-run in 2015 here. The coincidence of the church calendar it mentions is also true this year, 2018… the text has been slightly altered to align it with 2018’s calendar. The work detailed here outlines what I was doing twelve years ago. An update appears at the end of the column.)
I wish I had more time to work in the lab. (Here: measuring a meteorite’s heat capacity by seeing how much liquid nitrogen gets boiled off when I drop a sample into the dewar.) It’s a staged photo, of course; I rarely wear my collar in the lab!Next weekend marks an unusual event in our recent Church calendar: a Sunday in “Ordinary Time.” What with Lent and the Easter season, and then the special Feasts of the Trinity and Corpus Christi, Ordinary Time has been rare lately. But I’ve been celebrating “ordinary time” at the Vatican Observatory as well. Unusual for me, I’ve actually been able to manage a month’s uninterrupted work in my laboratory.
My airline’s frequent flyer program tells me I’ve flown over 27,000 miles since the last ordinary Sunday before Lent: an observing run at the Keck Telescope in Hawaii, a meeting at Nasa Headquarters in Washington, two dozen presentations from Arkansas to Newfoundland to Glasgow. Since 1996 I’ve spent more than half of every year on the road; come July and August I’ll be traveling one and a half times around the world. So this “ordinary time” now is something I treasure.
Much of this ordinary time is being spent doing an updated inventory of the Vatican’s meteorite collection. The work is simple but satisfying, weighing and photographing every sample and entering the information into a computer database. Though necessary work — without constant effort, rare samples easily get misfiled, mislabeled, and lost — it requires little in the way of creative thought. Rather, it is the kind of relaxing activity that allows the creative thoughts to come without bidding or strain.
Most of the meteorites I measure are “ordinary chondrites;” again, their importance to me is in their very ordinariness. Without characterizing what is usual, how can we recognize what is unusual? And so I measure basic physical properties like density and porosity for this kind of meteorite, which makes up 80% of all the stones seen to fall to Earth.
But are these meteorites really ordinary, or am I biased by looking at merely those samples that happen to be hitting the Earth nowadays? Perhaps most of our recent meteorites are coming from one or two nearby Earth-crossing asteroids, which for all we know could be anything but representative of material actually to be found in the main belt of asteroids orbiting between Mars and Jupiter. And who’s to say for certain that even the main belt asteroids accurately represent the material that went into forming the planets?
We know these meteorites, and the asteroids they came from, are as old as our solar system. Radioactive elements in their minerals have been decaying into stable isotopes within them, undisturbed for as long as their minerals have been solid crystals; by counting the relative isotope abundances, we can calculate that these crystals have been accumulating decay products for four and a half billion years. But that’s only a third of the age of the Universe. Old as they are, these rocks weren’t crystallized until long after the exciting events of the Big Bang were long over, and after several generations of stars had come and gone, creating the heavy elements that now make up asteroids, planets, and us. They too are a record only of “ordinary time.”
And yet, given our current understanding of cosmology, this time may be unique. Only now have stars made enough heavy elements to form planets and people, while still retaining enough hydrogen and helium to fuel the starlight that make our life possible. If the expansion of the universe goes on unabated (as, so far as we can tell, it will) then most of the Universe’s future will be cold and dark. Only now, for the next few tens of billions of years, can there be life-filled oceans and fields of foxgloves.
This is the early summertime in the life of the Universe. And to quote the poet James Russell Lowell (cousin of the astronomer Percival Lowell), what is so rare as a day in June?
(How have I been spending ordinary time this year, June of 2018? This year is an even numbered year, so that means I am in Castel Gandolfo with the students of our biennial summer school. Of course, as director, my ordinary time is very different now. I don’t get to do so much research, but I do wind up writing a lot more.)
