Daily briefing: mathematicians revive a ‘miraculous’, incomprehensible proof

Hello _Nature_ readers, would you like to get this Briefing in your inbox free every day? Sign up here. COP26 CLIMATE SUMMIT: TO DELAY OR NOT An international climate-action coalition is

calling for the postponement of the most significant global climate meeting since Paris in 2015. Climate Action Network-International (CAN), which represents a global collection of more than

1,500 environmental groups, warns that pandemic restrictions could prevent the world’s poorest nations from fully participating in the 26th United Nations Climate Change Conference of the

Parties (COP26). The conference has already been postponed by a year, ratcheting up concerns over delayed climate action. The UK government, which is hosting the event in Glasgow, has

responded to the call for postponement with concessions intended to enable broad participation. It is providing vaccines to delegations that do not have access to them and covering the cost

of hotel quarantine. Nature | 6 min read COVID IS DERAILING PROGRESS AGAINST DISEASES The COVID-19 pandemic has had a “devastating” impact on the fight against HIV, tuberculosis (TB) and

malaria. An assessment conducted by the Global Fund, an international organization that funds efforts to tackle these three health challenges, found that prevention, testing and treatment

services for all three dropped precipitously as countries went into lockdown and resources were diverted to combat the pandemic. “COVID-19 has been the most significant setback in the fight

against HIV, TB and malaria that we have encountered in the two decades since the Global Fund was established,” writes the organization’s executive director Peter Sands. Nature | 4 min read

FACE BITES REVEAL TYRANNOSAUR TEEN ANGST Tyrannosaurs’ skulls are covered in bite marks from other tyrannosaurs — which might be a sign that they battled it out around the time of sexual

maturity. Researchers examined more than 200 fossil skull bones of _Albertosaurus_, _Gorgosaurus_ and _Daspletosaurus _and found hundreds of scars that indicate repeated, non-lethal fights

between dinosaurs of around the same size. The youngest animals sported no scars, and as individuals matured, scars changed from predominantly fresh lesions to more healed injuries. If the

marks indicate the onset of sexual maturity in tyrannosaurs, the evidence suggests that it occurred when they were roughly half of their adult size. Live Science | 5 min read Reference:

_Paleobiology_ paper FEATURES & OPINION LAVOISIER PORTRAIT UNVEILS HIDDEN MEANINGS An iconic portrait of Enlightenment science hides hints of the French revolution. The 1788 painting

shows chemist Antoine Lavoisier with his wife and collaborator Marie-Anne Lavoisier, surrounded by scientific instruments that announce the couple’s place at the birth of modern chemistry. A

new analysis by conservators and curators at New York’s Metropolitan Museum of Art finds that the instruments were later additions and Marie-Anne once sported an ostentatiously fabulous

hat. Originally the painting appears to have focused on Antoine’s status as a wealthy tax collector for Louis XVI — a tricky position on the eve of revolution. Chemistry World | 6 min read

REVIVING A ‘MIRACULOUS’, PERPLEXING PROOF A new book offers to explain a trailblazing mathematical proof that was considered almost impossible to understand. “I probably didn’t treat the

exposition of the written material as carefully as I should have,” says Michael Freedman about his original 1981 proof, which attacked one of the biggest problems in topology. Normally I’d

have a go at giving you the gist, but in this case that seems the ultimate in hubris. Suffice it to say that _The Disc Embedding Theorem_ is a proof of the four-dimensional Poincaré

conjecture and it’s an absolute corker. Quanta | 16 min read INFOGRAPHIC OF THE WEEK Nearly 15% of confirmed COVID-19 infections in the United States have occurred in children — that’s more

than 4.8 million young people. But data collected by the US Centers for Disease Control and Prevention from hospitals across the country suggest that people under the age of 18 have

accounted for less than 2% of hospitalizations due to COVID-19 — a total of 3,649 children between March 2020 and late August 2021. Some children do get very ill, and more than 420 have died

of COVID-19 in the United States, but the majority of people with severe illness have been adults — a trend that has been borne out in many parts of the world. Research is beginning to

reveal that the reason children have fared well against COVID-19 could lie in the innate immune response — the body’s crude but swift reaction to pathogens. (Nature | 12 min read) See more

of the week’s key infographics, selected by _Nature_’s news and art teams. QUOTE OF THE DAY “THE IMPLICATION OF THAT IS THAT WE’VE LOST [THE] LAST 200 YEARS’ WORTH OF RECORDED TIME.”

Geoscientist Douglas Hardy is among the scientists racing to collect ice cores from glaciers and ice sheets around the world before they melt. Some of that ice is already gone. (Reuters | 7

min read)