Physicists fail to find mysterious 'sterile neutrino' particles

Researchers have, once again, failed to find any signs that hypothesised particles called sterile neutrinos exist. Neutrinos are some of the most abundant elementary particles in the Universe. There are three known types, but scientists have been searching for a fourth kind of neutrino for decades. If found, it could help to solve pressing problems in particle physics. Now, an experiment called MicroBooNE at the Fermi National Accelerator Laboratory did not turn up evidence of sterile neutrinos.

DNA reveals surprise ancestry of mysterious Chinese mummies

The genomes of 13 remarkably preserved 4,000-year-old mummies from China’s Tarim Basin suggest they weren’t migrants who brought technology from the West, as was previously supposed. Instead, the remains probably belong to Indigenous people who might have adopted agricultural methods from neighbouring groups. Researchers traced the ancestry of these early Chinese farmers to Stone Age hunter-gatherers who lived in Asia some 9,000 years ago.

Nearly 500 Mesoamerican monuments revealed by laser mapping — many for the first time

Scientists have uncovered nearly 500 ancient monuments in southern Mexico using an airborne laser mapping technology called lidar. Dating as far back as 3,000 years ago, the buried structures include huge artificial plateaus, built by the Olmec and Maya civilisations, that might have been used for ceremonial gatherings.

Signs of first planet found outside our galaxy

Astronomers have found hints of what could be the first planet ever discovered outside our galaxy. The possible planet, which is Saturn-sized, is in the Messier 51 galaxy, around 8 million parsecs away from the Milky Way. Nearly 5,000 planets orbiting stars beyond our Sun have been found so far, but all of these have been located within our galaxy.

Ancient DNA points to origins of modern domestic horses

Archæologists have used ancient DNA samples to identify the genetic homeland of modern horses, where the animals were first domesticated around 4,200 years ago. They found that modern domestic horses probably originated on the steppes around the Volga and Don rivers, now part of Russia, before spreading across Eurasia, ultimately replacing all pre-existing horse lineages.

Extinct Japanese wolf may hold clues to origins of dogs

The extinct Japanese wolf (Canis lupus hodophilax) might have come from a vanished population of grey wolves in east Asia that also gave rise to modern dogs. Researchers sequenced the genomes of nine specimens of the species (the last one was killed in 1905) to find where it sits on the canine evolutionary tree. The results, which have not yet been peer reviewed, show the Japanese wolf to be more closely related to the ancestor of dogs than are any other wolves found so far.

Physicists make most precise measurement ever of neutron’s lifetime

Physicists have measured the lifetime of the neutron more precisely than ever before. The average time it takes for the subatomic particle to decay is 877.75 seconds, according to an experiment that used magnetic fields to trap ultra-cold neutrons. The results have twice the precision of similar measurements, and are consistent with theoretical calculations. But they do not explain why neutrons live nearly 10 seconds longer in a different experiment that involves watching the particles decay as they move in a beam.

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The discrepancy might be explained by special relativity, according to which "clocks tick relatively more slowly" (time expands) for neutrons travelling in a beam.

First mission to the Trojan asteroids

The first spacecraft to journey to the Trojan asteroids, which share Jupiter’s orbit around the Sun, is set to lift off on 16 October. NASA’s Lucy mission — named after the iconic hominid fossil — will spend the next 12 years performing gravitational gymnastics to swoop past six of the asteroids. The Trojans probably formed when the planets were just coalescing, so exploring them can reveal more about the birth of the Solar System.

Evidence for tobacco use going back to the Pleistocene

Hunter-gatherers in North America might have been using tobacco around 12,300 years ago — 9,000 years earlier than was previously documented. Archaeologists found four burnt tobacco-plant seeds in an ancient hearth excavated in Utah. The seeds themselves were too small and fragile to be dated, but other burned woody material in the hearth is around 12,300 years old.

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.

First image of 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.