Hello Nature readers, would you like to get this Briefing in your inbox free every day? Sign up here. A close-up of the lutetium clock’s interior, which is the world’s most accurate timekeeper. Credit: Centre for Quantum Technologies, National University of Singapore Physicists have unveiled the world’s most accurate clock — a timepiece so reliable
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A close-up of the lutetium clock’s interior, which is the world’s most accurate timekeeper. Credit: Centre for Quantum Technologies, National University of Singapore
Physicists have unveiled the world’s most accurate clock — a timepiece so reliable that it would take more than 260 billion years to lose a second. The device is an ‘optical’ atomic clock, which derives time using the visible-range frequency of light at which an element — in this case, the rare-earth metal lutetium — absorbs radiation. The researchers behind the clock say that it is robust enough that they hope to be able to miniaturize it and eventually take it out of the lab.
Nature | 5 min read
Reference: Nature paper
Researchers have produced the largest map to date of gene activity in the human prefrontal cortex, a brain area that supports planning, decision-making and behavioural and emotional regulation. The atlas draws on donated samples from almost 1,500 people — from infants to centenarians — and the recorded gene activity in more than 6.3 million individual brain cells. The scale of the map will enable the study of neurodegenerative and psychiatric diseases that affect the prefrontal cortex in unprecedented detail.
Nature | 6 min read
Reference: PsychAD Consortium paper collection
A new phase of the element boron can be stretched, and has an electrical conductivity over a million times that of typical boron materials. The structure, called Imma-B60, is the first new unusual form of boron discovered since 2009. Researchers made it by coaxing boron to react with sodium under high pressure, then removing sodium impurities from the mixture. These properties suggest that the material could one day be used in solar panels, or to replace existing boron compounds in body armour.
Nature | 4 min read
Reference: Nature Chemistry paper
The SSRN preprint server has removed 257 papers authored or co-authored by a US statistician after others raised concerns about his unusual productivity. “It’s not only the volume, but the diversity of topics and how they differ from his past work,” says management professor Auyon Siddiq. The author, Nicholas Polson, told The Washington Post that he used AI tools to help produce the work. “Clearly AI makes a productive researcher far more productive,” he said.
The Washington Post | 9 min read
Gravitational and other forces generated by the movement of Earth’s metallic core can explain millisecond-length fluctuations in the length of the 24-hour day over decades. Researchers modelled the impact of various possible internal forces arising from interactions among Earth’s inner and outer cores, and its rocky mantle, which can subtly affect the rate of the planet’s rotation. They found that one scenario, in which a gravitational twisting force generated by the inner core was dominant, best matched the historical record of changes in the length of Earth’s days.
Nature | 5 min read
Reference: Nature paper
Figure 1 | Gravitational torque produces decade-long changes in day lengths. Zhang and Dumberry1 report that multidecadal variations in the length of a day are driven by gravitational torque exerted by Earth’s solid inner core on the mantle. The inner core has an ellipsoidal shape (the ellipticity is exaggerated in the graphic, for clarity), in part because of its interaction with two mantle regions called large low-velocity provinces. If the inner core is perturbed from its equilibrium position, it exerts a gravitational torque on the mantle. The authors’ model of gravitational torque predicts multidecadal variations in day length that are consistent with observations. The liquid outer core also exerts a torque on the mantle because of mechanical and electromagnetic drag forces at the core–mantle boundary, but the authors show that this torque acts in the opposite direction to the gravitational one and so cannot account for the observed multidecadal day-length variations. The cross-section is the plane of the Equator. (Adapted from Fig. 4 of ref. 1.)
Features & opinion
Researchers and leaders at some of the world’s foremost AI companies have raised concerns that artificial intelligence might kill us all. A hypothetical example that captures these worries is the ‘paperclip problem’ — a powerful AI system with a single-minded goal (such as making paperclips) could sacrifice everything else to achieve it. But others point to the more quotidian damage that is already happening, such as from disinformation, or concerns that fallible AI is being used in critical safety systems, such as in nuclear power plants. And some big-tech critics say that bigging up the dangers of AI could be an attempt to justify a slower pace of development to shareholders, or consolidate power among a handful of leading firms.
Nature | 7 min read
Hail is already one of the costliest weather hazards, and climate change is expected to make it worse. That’s why researchers in one of the most hail-prone places in the United States, Colorado, are learning everything there is to know about their foul-weather foe. It’s “the first time where we’ve been able to do a real comprehensive look at hail on the ground, hail aloft, the storm itself, the environment around the storm — just everything all at once”, says Becky Adams-Selin, the lead investigator of ICECHIP — the In-situ Collaborative Experiment for the Collection of Hail In the Plains.
High Country News | 9 min read
Today I’ve learned that not all roads lead to Rome — and they didn’t in the days of the Roman Empire either. A new analysis of roughly 300,000 kilometres of ancient roads suggests that Constantinople, now Istanbul, Turkey, might have been better connected than the empire’s namesake way back when.
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