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This scanning tunneling microscope image of a graphene sheet reveals that a ‘Wigner crystal’ — a honeycomb arrangement of electrons — has formed inside a layered structure underneath.Credit: H. Li et al./Nature
This is a solid made of electrons
If the conditions are just right, some of the electrons inside a material will arrange themselves into a tidy honeycomb pattern — like a solid within a solid. Physicists have now for the first time directly imaged these ‘Wigner crystals’, named after theorist Eugene Wigner. Researchers built a device containing atom-thin layers of two semiconductors and cooled it to just a few degrees above absolute zero. This slowed the electrons between the two layers enough so that they formed the elusive material.
Arctic sea ice hits 2021 minimum
This summer’s minimum Arctic sea-ice cover was the twelfth-lowest ever — and scientists warn that the long-term trend towards shrinking continues. Ice coverage declined to 4.72 million square kilometres on 16 September, the US National Snow and Ice Data Center has reported. Owing to a cool and cloudy Arctic summer, this year’s annual minimum was the highest since 2014. But such ‘good’ years are becoming rarer, putting pressure on animals, such as polar bears, that rely on the ice.
Jupiter’s Great Red Spot is swirling faster
The winds spinning around the outer edge of Jupiter’s striking Great Red Spot are speeding up, according to long-term observations by the Hubble telescope. Observations over the past century have already revealed that the storm is mysteriously shrinking. Hubble data collected between 2009 and 2020 add a new twist. Compared with a decade ago, when wind speeds in the Great Red Spot’s outer ring were typically just above 90 metres per second, they now exceed 100 metres per second.
Reference: Geophysical Research Letters paper
Features & opinion
Starting in science: the real story
Over the past three years, Nature reporters have documented, in real time, two scientists’ journeys through a pandemic and a personal crisis. Spouses Alison Twelvetrees, a neuroscientist, and molecular biologist Daniel Bose have each taken on the epic challenge of launching their own laboratory. In part two of this three-part story, Ali and Dan try to keep the lights on at their new labs while designing experiments, preparing lectures and supervising students.
Lessons from Microsoft’s ‘net zero’ plan
In January, Microsoft announced that it had paid for the removal of 1.3 million tonnes of carbon dioxide from the atmosphere. Among its purchases were projects to expand forests in the Americas, regenerate soil across US farms and entomb carbon in rocks in Iceland. Microsoft staff working on the company’s carbon-negative programme and research scientists who analyse strategies for carbon reduction and removal summarize the lessons learnt. They also describe the barriers that stand in the way of the company’s ultimate goal, which it plans to reach by 2050: removing all of the emissions it has produced since it was founded in 1975.
News & views
Flies sense the world while sleeping
When asleep, humans are able to respond to important stimuli — such as a baby crying — while filtering out more-trivial sensory cues. Now we know that fruit flies can, too. Normally, sleeping fruit flies are more likely to wake up when they smell an odour that they dislike when they’re awake. But when the flies fell asleep hungry, the scent of food became more likely to jolt them out of dreamland — implying that flies process olfactory information, as well as the value attached to different odorants, during sleep. “These findings suggest that the fruit fly, with a brain of only about 100,000 neurons, could be used to investigate how sensory processing differs between sleeping and waking states,” write biologists Wanhe Li and Alex Keene.
Nature | 6 min read (Nature paywall)
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Figure 1 | A fly’s internal state affects its response to sensory information during sleep. Using a machine called an ethoscope, French et al. delivered various odorants to Drosophila melanogaster fruit flies when the insects were asleep, and tracked the flies’ behavioural responses. The authors found that food odours and non-food odours awakened the flies at a similarly low rate. However, if the flies were starved of food, they woke up much more readily in response to food odours, but not to non-food odours. This finding implies that flies continue to process olfactory information, as well as the value attached to different odorants, during sleep.
