Wednesday, May 22, 2024

Daughters of the moon

One of the delights of graduation is standing in line, well not the standing-in-line part, but the who-I'm-standing-in-line-with part, sometimes with colleagues I haven't seen since last commencement. I am privileged to work with some pretty amazing people, and this year stood across from a colleague who is an award-winning poet (she won a Guggenheim!). We chatted about the moon, its moods and modes, how it can seem to loom so large in certain places. Her students, she tells me, are in love with the moon. My students, I confess, not so much.

We wondered what it might be like to swap classes, perhaps my students could learn to swoon over the moon as hers do, and perhaps her students might enjoy raiding my language for their own purposes. I would tell them about the daughters of the moon, that carry the history of their mothers with them in their cores, bearing it forward billions of years. A process in which decay does not mean loss and despair, but instead transformation and eventual stability.

My students are peevish about the moon because of a problem we worked about dating the rocks brought back by the Apollo missions. It's a problem that crosses two of the topics we've discussed, chemical kinetics and nuclear chemistry. I'm fond of the problem because it uses material from the very beginning of the course and from the very end and shows both how they are connected and can be used in a very practical way by another field. But making connections can be challenging, and at the end of the semester my students are tired. They are less intrigued and more resigned.

The moon, like the earth and pretty much everything on it, contains radioactive elements. Sometimes these radioactive atoms are versions of stable elements, sometimes all of the versions of an element are radioactive. (Carbon-14 is radioactive while the most common carbon atoms on earth, called carbon-12, are not. On the other hand, there are no stable versions of uranium.) Radioactive elements are like tiny clocks, transforming themselves from one element into another at a particular and fixed rate. Comparing the amounts of a radioactive element at two different times can tell you the time spanned. For example, if an artifact like a wooden carving has 50% of the carbon-14 that it had when it was made, 5500 years have elapsed since its creation. We say carbon-14 has a half-life of 5500 years.

These built-in atomic clocks can run on short timescales, a matter of days or seconds, or on incredibly long timescales. The rule of thumb is that a given radioisotope can measure out time spans up to 10 times the half-life. So carbon-14 can be used to date materials up to about 55,000 years old. Potassium-40, the main reason human beings themselves are radioactive, has a half-life of 1.3 billion years and can time processes going back to the Big Bang.    


Uranium-238 gives birth to daughters such as thorium-234, radium-226 and polonium-218. (I note that some of these daughters were discovered by a daughter and a mother, Marie Curie.) Eventually all her energy is exhausted and U-238 finally plops down onto the island of stability as lead-206. This is not a short process, it takes 45 billion years for (nearly) all of the U-238 to find its way to the stable space of lead-206. But her daughters will hold tight to her history all along the way.  And we can read it in their very identities.  

Monday, April 22, 2024

Itadakimasu: wearing gratitude

“Itadakimasu," a Japanese word said before eating, roughly translates as "I humbly receive." It's an expression of gratitude for the meal and for those who prepared it. When I traveled to Japan with students we taught them to say, “Itadakimasu” before any meal.

A film crew from a Japanese news show came on the Friday after my book launched to interview me about the kerfuffle around the salt but also about the making of tea. (You can watch it here, the scene where I make a cup is at the beginning. Yes, it’s in Japanese.)

They had asked me to be prepared to make a cup of tea for them on camera, which I did. When I handed the interviewer the cup that I had made, he murmured, "Itadakimasu." In all the whirlwind of those days that one word — said so quietly, so matter of factly — touched me deeply.

I’m grateful for so much lately. I’m trying to “wear gratitude like a cloak” (to quote Rumi) to let it be what I wrap myself in, to let it be what I show first to the world. Itadakimasu.

Saturday, April 20, 2024

Lessons in chemistry


One of the questions I’ve often been asked in the interviews I have done around the tea book has been, “Have you read the book Lessons in Chemistry?” and when I acknowledge that I have, the logical follow up:“What did you think of it?”

The first time the question arose I was surprised, and had to scramble for an answer. I shouldn’t have been. It is a best selling book, it has been made into a series. It has chemistry in the title. The interviewer is fishing for a bridge to what’s in the current cultural zeitgeist. 

But for me the answer is, as the kids say, complicated. Even though the book is set slightly earlier than my time as a graduate student and newly minted scientist, my experiences were not so different from Elizabeth Zott’s. There was enough similarity that it was an uncomfortable read at the start. And then there is the day that Elizabeth‘s partner is suddenly killed. When I was reading the book, it was like a gut punch.  It was as if some enormous hand had picked me up and dumped me back into the confusion and chaos of that April night when Tom died so suddenly. Still, I needed to read to the end. I had to know if Elizabeth made it out of the depths of grief. Truth  be told if I known what the plot was, I wouldn’t have read the book. (I really want something like the website “Does the dog die?” for books. No children in peril, no suddenly grieving widows.)

Of course, to say that I found the book difficult for a very personal reason is not the answer a reporter is looking for. I finally settled on saying that I enjoyed the scenes where Elizabeth gave as good as she got, and that the historical difficulties of being a woman in science inspired me to teach the next generation. True, and truly bland. Next question!

Monday, April 08, 2024

Scathed by totality






"There is a mysterious woundedness that somehow goes with great blessing. When we truly encounter the night in all its beauty and terror, we have no assurance whatsoever that we are going to come out unscathed."

— David Steindl-Rast


 I came to upstate New York, to Canandaigua on the Finger Lakes, to give a retreat around the theme of the solar eclipse, and then stayed to experience totality. The weather forecast oscillated for days, partly sunny to mostly sunny and back to partly sunny and finally to mostly cloudy. And mostly cloudy it was. We had a single glimpse of the sun about two minutes before the moon began to eat away at the disc. As the time approached for totality, there was really no sign that an eclipse was on the way. I wondered if this would just be like the experience of a thunderstorm where the sky grows dark, but night doesn't fall. I fitfully checked the radar on my phone, hoping that the break in the image would translate to, if not clear skies, clearer skies. It did not. 


The clouds were louring and dark, as before a summer thunderstorm. It grew colder. Suddenly there was a deep violet funnel shape visible on the horizon. Even with the sun hidden behind the clouds, we could see the shadow of the moon flying at us at 1800 mph. It got darker and darker. The horizon, where the shadow had yet to fall, was smudged with the deep pastel colors of sunset. And it got darker yet. Nightfall had come. 


Totality lasted over three minutes where I was standing. Three minutes is longer than you think in these conditions. Annie Dillard was right. The difference between a total eclipse and a partial eclipse is like the difference between kissing someone and marrying them. I have seen partial eclipses, the first in Illinois when I was young (1963), one unexpected in California, and one in 2017. This was nothing like them. While I wished I could've seen the corona, the swiftness of nightfall, and the swifter return of light left me breathless. The enormity of that shadow hovering over us rang a disquieting chord inside of me. And it did not leave me unscathed.

Friday, December 15, 2023

Taking tea with a grain of salt - the Boston tea party


Tomorrow is the 250th anniversary of the Boston Tea Party, the day protesting American colonists dumped 42,000 kg1 of tea into Boston Harbor. That's enough to make about 21,000,000 cups of tea. While that might sound like a lot of tea, several billion cups of tea  are drunk across the world  every day2. Each year humans drink enough tea to to fill Boston Harbor end to end. That's a bit less than half a cubic kilometer (which in those terms I confess does not sound like very much - but Boston Harbor).

The tea, once dumped in the harbor, was unusable due to contamination not only by the salt water, but by the sewage that surely polluted the bay. (I was fascinated to find that a vial of the tea leaves purportedly collected from the harbor still exists.)

Salt would seem to be the last thing you want in your tea, but in the eighth century manuscript Classic of Tea, the tea master Lu Yu recommended adding a dash of salt to water before using it to brew tea. Salt, actually the sodium ions in it, suppresses our perception of bitterness. A small amount of salt, not even enough to taste, reduces the bitterness in a cup of tea. Other ions will do this too, including zinc. Beware, zinc also interferes with the perception of sweet!


1. If you prefer this in Imperial units, that would be 92,000 pounds.
2. At this point I'm apparently contractually required to tell you that tea is the most popular beverage in the world. Virtually everything I read about tea made sure to make this point early and often.


If you want to know more about the chemistry behind tea, my book Steeped: The Chemistry of Tea comes out from the Royal Society of Chemistry Books in January 2024. You can sign up to hear me talk about the chemistry of tea on February 15 with Chemistry World.