Mathematicians discover long-sought "Dedekind number"

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August 17, 2023

This week, we're talking about "Dedekind numbers" and doing the seemingly impossible. These numbers are not easy to concisely explain (read our lead story for that) but the gist is that they are a sequence counting the myriad configurations that certain logical functions can hold across an ever-growing number of spatial dimensions. Each successive number in the sequence thus becomes exponentially more complex—and correspondingly more difficult to calculate. The computational challenge is so great, in fact, that only nine of these numbers have been pinned down since the 19th-century revelation of the sequence's existence, with the ninth's discovery coming from two independent teams earlier this year. Elsewhere this week, we have stories on quantum superchemistry, mysterious and beautiful "pinwheel" stars, the wishful thinking behind fizzled superconductivity claims, and more. Enjoy!

Lee Billings, Senior Editor, Space & Physics

Mathematics Mathematicians Discover Long-Sought 'Dedekind Number' Researchers have found the ninth "Dedekind number" after a 32-year-long search By Leila Sloman

Astronomy Arecibo Observatory Shuts Down Its Science Although Arecibo Observatory is slated to become an education center, astronomers hope research might one day return to the site By Anil Oza,Nature

Energy The Superconductor Sensation Has Fizzled, and That's Fine The rise and fall of LK-99 offers a lesson on how to consider technology's role in urgently needed energy transitions By Lauren Leffer

Astronomy Rare 'Pinwheel' Stars Are a Beautiful Astronomical Puzzle The doomed class of stars named Wolf-Rayets produce mysterious pinwheel shapes By Peter Tuthill

Astronomy Earendel, the Most Distant Known Star, Reveals Its Secrets to JWST A new view of a record-shattering distant star shows it to be twice as hot as our sun and likely accompanied by a stellar companion By Mike Wall,SPACE.com

Basic Chemistry 'Quantum Superchemistry' Observed for the First Time Ever A new type of chemistry performed at very cold temperatures on very small particles enables quick, precise reactions By Stephanie Pappas,LiveScience

Policy Oppenheimer Reminds Scientists to Speak Up for a Better World The world needs more scientists to get off the sidelines during policy debates By Dan Correa

Space Exploration Russia Launches First Moon Mission after Half-Century Hiatus The Luna 25 spacecraft will attempt to land at the lunar south pole for the first time in a hunt for valuable water ice By Jonathan O'Callaghan,Nature magazine

QUOTE OF THE DAY "I think it's pretty safe to say the 10th one will not be calculated soon, and by 'soon,' I mean the next few hundred years." Lennart Van Hirtum, a Ph.D. student at Paderborn University in Germany and co-discoverer of the 9th "Dedekind number"

FROM THE ARCHIVE Arecibo's Collapse Sends Dire Warning to Other Aging Observatories The iconic telescope's tragic end foreshadows future battles over the fate of various legacy facilities By Robin George Andrews | December 2020

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