One of my favorite anecdotes about prime numbers concerns Alexander Grothendieck, who was among the most brilliant mathematicians of the 20th century. According to one account, he was once asked to name a prime number during a conversation. These numbers, which are only divisible by 1 and themselves, form the atoms of number theory, so to speak, and have fascinated humankind for thousands of years.
Grothendieck is said to have replied: “57.” Although it is hard to determine the truth of this story, 57 has since been known in nerd circles as the Grothendieck “prime number”—even though it is divisible by 3 and therefore not a prime number.
After several years of drought, it's dustier than ever. The shallow fountains have been drained, and the city has even taken to chopping down wilting palm trees before they can topple over. In eastern Catalonia, the three years from 2021-23 had some of the worst drought in recorded history.
But at certain points through winter 2024, beneath the park, a huge cistern 17m (58ft) deep becomes filled with cloudy rainwater. These are the two extremes the city finds itself in, where there can be too much water and still not enough.
Aquatic invasive species (AIS) have been making trouble for Lake Tahoe’s ecosystem ever since people started sticking them in there in the mid-1800s. Invasives crowd out native plants, starve out or prey upon native animals, and kick off disastrous ecological cascades. Increasingly, limnologists are finding alliances like that of clam and algae—in which aquatic invasive species create conditions that help other undesirables spread. They’re aided by a third accomplice: climate change. Warmer waters are worse for native species, and better for invasives and potentially harmful algae. At Lake Tahoe, native fish stocks have declined, toxic algae alerts have closed down beaches, and the celebrated waters are about 30 percent murkier than they were 50 years ago. The lake’s ecosystems, along with its multibillion-dollar tourism industry, rely on clear, clean, cool water. Tahoe—jewel of the Sierra, sacred space of the Washoe Tribe, and destination for nearly six million vacationers each year (including about a million from the Bay Area alone)—is at risk.
The subtitle to this edition of William Wordsworth’s The Prelude provides a hint of just how jam-packed the book is with ancillary material. “Newly Edited from the Manuscripts [by James Engell and Michael D. Raymond] and Fully Illustrated in Color with Paintings and Drawings Contemporaneous with the Composition of the Poem,” the volume also includes “an Introduction, Maps, Notes, Glosses, and Chronology.” If that’s not enough to keep a reader immersed in the text, there is an insightful and appreciative afterword by the late Helen Vendler.