Physicists trace the rise in entropy to quantum information

The second law of thermodynamics expresses a fundamental truth about the Universe — that entropy, a measure of disorder, will always increase. Now some physicists are proposing that the law comes about because of quantum effects such as entanglement. In this telling, an increase in entropy is not just the most likely outcome of change, it is a logical consequence of quantum behaviour.

Black-hole image sheds light on Milky Way mysteries

The first image of our Galaxy’s supermassive black hole, released earlier this month, has already begun to explain some enduring mysteries about the heart of the Milky Way. Alongside other evidence, the results suggest that Sagittarius A* is sucking in matter at a slow pace, making it unusually dim compared with the central black holes of other galaxies. The observations also hint that Sagittarius A* could have been spectacularly active only a few million years ago. And there are fresh questions about some of the largest structures seen in and around the Milky Way.

‘Mind blowing’ ancient settlements uncovered in the Amazon

The southwest corner of the Amazon Basin was once the site of complex urban settlements built by ancient civilisations. Researchers used a laser remote-sensing technology called lidar to map land inhabited by the Casarabe culture, which existed around AD 500 to 1400 in what is now Bolivia. Observations from the air reveal that Casarabe people lived in densely populated centres, featuring 22-metre-tall earthen pyramids, that were encircled by kilometres of elevated roadways. They also had large water-management infrastructure made of canals and reservoirs.

Can galaxies form without dark matter?

Scientists think that galaxies cannot form without the gravitational pull of dark matter. But astronomers might have observed a line of 11 galaxies that don’t contain any dark matter, which could all have been created in an ancient collision. Some are unconvinced that the claim is much more than a hypothesis.

Ancient tooth suggests Denisovans ventured far beyond Siberia

A fossilised tooth unearthed in a cave in northern Laos might have belonged to a young Denisovan girl who died between 164,000 and 131,000 years ago. If confirmed, it would be the first fossil evidence that Denisovans — an extinct hominin species that co-existed with Neanderthals and modern humans — lived in southeast Asia. The molar would be only the second Denisovan fossil found outside Siberia, but millions of people with Asian, Oceanian or Pacific Islander ancestry carry traces of Denisovan DNA.

Ancient DNA maps ‘dawn of farming’

Europe’s first farming populations descend mostly from farmers in the Anatolian peninsula, in what is now Turkey. And the ancient Anatolian farmers descended from repeated mixing between distinct hunter-gather groups from Europe and the Middle East. A pair of ancient-DNA studies — including one of the largest assemblages of ancient human genomes yet published — reveal finer details of the dawn of farming, thanks to ‘high coverage’, or high-quality, genomes — a rarity in ancient-genomics work.

Origin of life theory involving RNA–protein hybrid gets new support

Chemists say they have solved a crucial problem in a theory of life’s beginnings, by demonstrating that RNA molecules can link short chains of amino acids together. This might have allowed for ever-more complex RNAs, proteins and combinations of the two — a possible path to the chemistry of life that we know today. The findings support a variation on the ‘RNA world’ hypothesis, which proposes that, before DNA evolved, the chemical ancestors of biological life were based on RNA.

Black hole at the centre of our Galaxy imaged for the first time

Below is Sagittarius A* — the black hole at the centre of our galaxy. It’s only the second time a black hole has been directly imaged. Like the first such image — of the supermassive black hole at the centre of a nearby galaxy called M87, in 2019 — astronomers created the picture by processing radio-wave observations that are invisible to the human eye. The long-awaited results were obtained from data collected in 2017 by the Event Horizon Telescope, a global network of radio observatories. Sagittarius A* seems to be rotating anticlockwise along an axis that roughly points along the line of sight to Earth.

Bats buzz like hornets to scare off owl predators

Some bats can imitate the sound of buzzing hornets to scare off owls — the first documented case of a mammal mimicking an insect to deter predators. Researchers compared the sound structure of buzzing by the European hornet (Vespa crabro) to that of the distress call of greater mouse-eared bats (Myotis myotis). At most frequencies, the two sounds were not dramatically similar, but they were when the bat’s call was stripped down to include only frequencies that owls can hear.

A ‘galaxy’ is unmasked as a pulsar

An object that astronomers thought was a distant galaxy is actually the brightest extra-galactic pulsar ever seen. Pulsars are among the few celestial objects that emit circular polarised light, so scientists used a computer program that works like sunglasses: it filters out other kinds of light. The team could then spot the ‘hidden’ pulsar.