American Scientist

With this November–December issue, we close out 2019 with a special spotlight on some notable anniversaries of historic scientific events.

This year marks the 150th anniversary of the first iteration of Dmitri Ivanovich Mendeleev’s periodic table of chemical elements. Mendeleev wasn’t the only scientist trying to organize the elements, of course, but as Abhik Ghosh and Paul Kiparsky note in this issue’s Perspective column, he deserves credit for his appreciation of the elements’ periodic properties, which led him to leave gaps in his table for elements not yet discovered. Mendeleev used Sanskrit names of numbers to mark gaps in his table. As the authors say, let that sink in. Why not Latin, or Greek, or German? I won’t spoil the story, but in “The Grammar of the Elements,” Ghosh and Kiparsky make a compelling case that Mendeleev was likely to have been exposed to Sanskrit and that the grammar of that ancient language could have influenced his organizational thinking about the periodic table.

The celebration of the periodic table continues with a blog from chemist and historian of science Eric Scerri, who gives his perspective on the events of the International Year of the Periodic Table and on some current debates surrounding the table and the elements themselves. Included with this blog post is a convenient list of content that has appeared in the magazine about the periodic table.

Another notable scientific anniversary being celebrated this year is the centenary of a famous pair of scientific expeditions sent to view the 1919 total solar eclipse. The missions were designed to measure whether the paths of light from distant stars would bend as the starlight passed the Sun, making the stars seem to move position—and stars are only visible in the sky near the Sun when the Sun is dark during an eclipse. Such a deflection of starlight would confirm one of Einstein’s most famous predictions based on his general theory of relativity: that space is curved and that light’s path will curve as it passes a massive body. Despite some adverse viewing conditions and faulty equipment, the expedition leaders made some measurements and declared that the data they found supported Einstein. The news that Einstein’s theory had been validated was widely trumpeted in the press at the time. But 50 years later the results were attacked as biased. Now, as Cornell University science and technology studies professor Suman Seth discusses in Scientists’ Nightstand, the authors of two recent books have reexamined the evidence and make the case anew that the findings of these expeditions do support Einstein’s theory. It’s a fascinating story about the role of preconceived ideas and politics in the acceptance of scientific results.

In this issue we once again feature the writing of Michael Werner, the lead scientist for the Spitzer Space Telescope, who wrote in our pages about that instrument in 2009. A decade later he returns with Jet Propulsion Laboratory senior research scientist Peter Eisenhardt to discuss how Spitzer has illuminated our view of the lives of comets (“Comets Are Not Forever”). The Spitzer Space Telescope was launched in 2003, and after 16 years in space, it has a planned retirement coming up in January 2020, so it’s a fitting time to pay homage to this astrophysical workhorse.

What new scientific results will 2020 bring that will be celebrated as milestones decades from now? Let us know what your research finds. We’re always interested in new discoveries.—Fenella Saunders (@FenellaSaunders)