Carlo Rovelli on the bizarre world of relational quantum mechanics

Physicist Carlo Rovelli explains the strange principles of relational quantum mechanics - which says objects don't exist in their own right - and how it could unlock major progress in fundamental physics

Physics



10 October 2022

By Michael Brooks

Carlo Rovelli at the Cornelia Parker exhibition, Tate Britain

David Stock

Carlo Rovelli stands in front of an exploding shed. Fragments of its walls and shattered contents – parts of a child’s tricycle, a record player, a shredded Wellington boot – hang in mid-air behind him. I have come to meet the physicist and bestselling author at an exhibition at the Tate Britain art gallery in London. The scattered objects are the work of Cornelia Parker, one of the UK’s most acclaimed contemporary artists, known for her large-scale installations that reconfigure everyday objects.

For Rovelli, based at Aix-Marseille University in France, Parker’s work is meaningful because it mirrors his take on the nature of reality. “I connect with the process: of her coming up with the idea, producing the idea, telling us about the idea and of us reacting to it,” he tells me. “We don’t understand Cornelia Parker’s work just by looking at it, and we don’t understand reality just by looking at objects.”

Rovelli is an advocate of an idea known as relational quantum mechanics, the upshot of which is that objects don’t exist independently of each other. It is a concept that defies easy understanding, so Parker’s reality-challenging exhibition seemed like it might be a helpful setting for a conversation about it – and about what else Rovelli is up to. It is a happy coincidence that Parker’s shed is called Cold Dark Matter, a reference to the unidentified stuff that is thought to make up most of the universe. Because Rovelli now thinks he knows how we might finally pin …

#Physics | https://sciencespies.com/physics/carlo-rovelli-on-the-bizarre-world-of-relational-quantum-mechanics/

Synthetic fibers discovered in Antarctic air, seawater, sediment and sea ice as the 'pristine' continent becomes a sink for plastic pollution

As nations meet in Uruguay to negotiate a new Global Plastics Treaty, marine and forensic scientists publish new results this week that reveal the discovery of synthetic plastic fibres in air, seawater, sediment and sea ice sampled in the Antarctic Weddell Sea. The field research was undertaken during an expedition to discover Sir Ernest Shackleton's ship, the Endurance. The results are published in the journal Frontiers in Marine Science.

Fibrous polyesters, primarily from textiles, were found in all samples. The majority of microplastic fibres identified were found in the Antarctic air samples, revealing that Antarctic animals and seabirds could be breathing them.

'The issue of microplastic fibres is also an airborne problem reaching even the last remaining pristine environments on our planet', stated co-author Professor Lucy Woodall, University of Oxford, Nekton Principal Scientist. 'Synthetic fibres are the most prevalent form of microplastic pollution globally and tackling this issue must be at the heart of the Plastic Treaty negotiations.' Professor Woodall was the first to reveal the prevalence of plastic in the deep sea in 2014.

A modelling analysis of air trajectories revealed that areas with higher numbers of fibres were associated with winds coming from southern South America. The discovery reveals that the Antarctic Circumpolar Current and the associated polar front is not, as previously thought, acting as an impenetrable barrier which would have prevented microplastics from entering the Antarctic region.

'Ocean currents and winds are the vectors for plastic pollution to travel across the globe and even to the remotest corners of the world', shared Nuria Rico Seijo, Nekton Research Scientist, Oxford, the co-lead author of the research. 'The transboundary nature of microplastics pollution provides more evidence for the urgency and importance of a strong international plastic pollution treaty.'

The concentration of microplastics was also discovered by the team to be far higher in sea ice than in other sample types. Research indicates that microplastics are being trapped during the creation of the sea-ice layer every year.

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'Sea ice is mobile, can travel vast distances and reach the permanent ice shelves of the Antarctica continent where it can be trapped indefinitely with its gathered microplastic pollutants', shared Dr Mánus Cunningham, Nekton Research Scientist, Oxford, the co-lead author of the research. 'We believe the acquisition of microplastics in the multi-year sea ice combined with its seasonal changes could also be considered a temporary sink and one of the main transporters of microplastics within the Antarctic region', concluded Dr Cunningham.

Extensive research was also conducted on sediment samples retrieved at depths ranging from 323 to 530 metres below the sea's surface during the Weddell Sea Expedition. 'Our discovery of microplastics in seabed sediment samples has revealed evidence of a plastic sink in the depths of the Antarctic waters', said Professor Woodall. 'Yet again we have seen that plastic pollution is being transported great distances by wind, ice and sea currents. The results of our research collectively demonstrate the vital importance of reducing plastic pollution globally.'

The scientific and forensic experts at Nekton's Oxford University and collaborating laboratories (Staffordshire University, University of Cape Town and Nelson Mandela University) used a range of investigative methods to analyse the samples in the study. These include optical (Polarised Light Microscopy), chemical (Raman Spectrometry) investigative technologies and even a specialist adhesive "crime scene" tape to identify the polymer type. The modelling analysis used a method called Air Mass Back Trajectory analysis.

'Our use of forensic science approaches had two important benefits; improved methods for both the reduction and monitoring of possible procedural contamination in the samples, and also more detailed characterisation of the microplastics, beyond just polymer type, allowing for better understanding of the number of possible sources. We would encourage future studies to harness these forensic approaches to ensure more robust data is gathered' said Professor Claire Gwinnett, Staffordshire University.

According to the research team, the findings add urgency for a binding, globally agreed treaty to prevent microplastics from entering the environment, particularly oceans. Ahead of the Global Plastic Treaty discussions, they call on policy makers to:

• Reduce plastic pollution and production globally, by creating a robust global plastics treaty that builds on national and regional initiatives;
• Align plastic reduction actions with natural and societal targets to achieve multiple positive outcomes for society;
• Empower local communities to co-develop and use programmes that support full life-cycle solutions to plastic waste management.

They add that concerned individuals can also play their part by adopting simple lifestyle habits to reduce synthetic microfibre pollution. These include:

1. Fill your washing machine: more space to move around in the wash results in microfibres falling off.
2. Wash at 30C: gentle cycles and lower temperatures decreases microfibre shedding.
3. Ditch the dryer: tumble dryers generate about 40 times more microfibers than washing machines.
4. Microfibre capture for washing machines, e.g. GuppyFriend (https://guppyfriend.com) or Coraball (https://www.coraball.com).
5. Choose natural fibres, e.g. organic natural fibres like cotton, linen, hemp.
6. Avoid microfibre cleaning cloths -- use natural alternatives.
7. Wash textiles less!

Video: https://youtu.be/8fDbfm6B2JY

Story Source:

Materials provided by University of Oxford. Note: Content may be edited for style and length.

#Environment | https://sciencespies.com/environment/synthetic-fibers-discovered-in-antarctic-air-seawater-sediment-and-sea-ice-as-the-pristine-continent-becomes-a-sink-for-plastic-pollution/

Mussel survey reveals alarming degradation of River Thames ecosystem since the 1960s

Scientists replicated a 1964 River Thames survey and found that mussel numbers have declined by almost 95%, with one species -- the depressed river mussel -- completely gone.

The detailed study measured the change in size and number of all species of mussel in a stretch of the River Thames near Reading between 1964 and 2020.

The results were striking: not only had native populations severely declined, but the mussels that remained were much smaller for their age -- reflecting slower growth.

Mussels are important in freshwater ecosystems because they filter the water and remove algae. As filter feeders they're exposed to everything in the water, and this makes them a valuable indicator of ecosystem health. Mussel shells also provide places for other aquatic species to live.

"Mussels are a great indicator of the health of the river ecosystem. Such a massive decline in mussel biomass in the river is also likely to have a knock-on effect for other species, reducing the overall biodiversity," said Isobel Ollard, a PhD student in the University of Cambridge's Department of Zoology and first author of the report.

She added: "The depressed river mussel used to be quite widespread in the Thames, but this survey didn't find a single one -- which also raises concerns for the survival of this species."

The study also recorded new arrivals: the invasive, non-native zebra mussel, Dreissena polymorpha, and Asian clam, Corbicula fluminea - both absent from the original 1964 survey -- were present in high numbers. The scientists say invasive species probably hitched a ride on boats as they sailed up the Thames, and established themselves in the river.

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The results are published today in the Journal of Animal Ecology.

"This dramatic decline in native mussel populations is very worrying, and we're not sure what's driving it," said Professor David Aldridge in the University of Cambridge's Department of Zoology, and senior author of the report.

He added: "While this might seem like a rather parochial little study of a single site in a single river in the UK, it actually provides an important warning signal about the world's freshwaters."

The invasive species could be behind the decline in the native mussel populations: zebra mussels are known to smother native species to death. But the scientists say more work is needed to be sure. Other causes could be changes in land use along the river, or changes in the fish populations that mussels depend on as part of their life cycle.

Many empty shells of the depressed river mussel, Pseudanodonta complanata, were found in the survey, indicating that the species had been living at this site in the past. The depressed river mussel is one of the most endangered mussel species in the UK.

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The survey found that the population of duck mussels, Anodonta anatina, had decreased to just 1.1% of 1964 levels, and the painter's mussel, Unio pictorum, decreased to 3.2%.

The scientists think the mussels' reduced growth rate may reflect the river's return to a more 'natural' state. Since 1964, levels of nitrate and phosphate in the river water have fallen due to tighter regulation of sewage treatment. A reduction in these nutrients would reduce the growth of algae, limiting the food available to the mussels.

Mussel species are threatened globally. The scientists say that regular population surveys of key species, like this one, are essential to tracking the health of rivers and guiding their management.

To ensure the survey was an exact replica of the original, Ollard contacted Christina Negus -- who had done her survey while a researcher at the University of Reading in the sixties. Negus, who is no longer a scientist, shared details of the methods and equipment she had used. Her report, published in 1966, continues to be cited extensively as evidence of the major contribution mussels make to ecosystem functioning in rivers.

Story Source:

Materials provided by University of Cambridge. Original written by Charis Goodyear. The original text of this story is licensed under a Creative Commons License. Note: Content may be edited for style and length.

#Environment | https://sciencespies.com/environment/mussel-survey-reveals-alarming-degradation-of-river-thames-ecosystem-since-the-1960s/

Mussel survey reveals alarming degradation of River Thames ecosystem since the 1960s

Scientists replicated a 1964 River Thames survey and found that mussel numbers have declined by almost 95%, with one species -- the depressed river mussel -- completely gone.

The detailed study measured the change in size and number of all species of mussel in a stretch of the River Thames near Reading between 1964 and 2020.

The results were striking: not only had native populations severely declined, but the mussels that remained were much smaller for their age -- reflecting slower growth.

Mussels are important in freshwater ecosystems because they filter the water and remove algae. As filter feeders they're exposed to everything in the water, and this makes them a valuable indicator of ecosystem health. Mussel shells also provide places for other aquatic species to live.

"Mussels are a great indicator of the health of the river ecosystem. Such a massive decline in mussel biomass in the river is also likely to have a knock-on effect for other species, reducing the overall biodiversity," said Isobel Ollard, a PhD student in the University of Cambridge's Department of Zoology and first author of the report.

She added: "The depressed river mussel used to be quite widespread in the Thames, but this survey didn't find a single one -- which also raises concerns for the survival of this species."

The study also recorded new arrivals: the invasive, non-native zebra mussel, Dreissena polymorpha, and Asian clam, Corbicula fluminea - both absent from the original 1964 survey -- were present in high numbers. The scientists say invasive species probably hitched a ride on boats as they sailed up the Thames, and established themselves in the river.

advertisement

---

The results are published today in the Journal of Animal Ecology.

"This dramatic decline in native mussel populations is very worrying, and we're not sure what's driving it," said Professor David Aldridge in the University of Cambridge's Department of Zoology, and senior author of the report.

He added: "While this might seem like a rather parochial little study of a single site in a single river in the UK, it actually provides an important warning signal about the world's freshwaters."

The invasive species could be behind the decline in the native mussel populations: zebra mussels are known to smother native species to death. But the scientists say more work is needed to be sure. Other causes could be changes in land use along the river, or changes in the fish populations that mussels depend on as part of their life cycle.

Many empty shells of the depressed river mussel, Pseudanodonta complanata, were found in the survey, indicating that the species had been living at this site in the past. The depressed river mussel is one of the most endangered mussel species in the UK.

advertisement

---

The survey found that the population of duck mussels, Anodonta anatina, had decreased to just 1.1% of 1964 levels, and the painter's mussel, Unio pictorum, decreased to 3.2%.

The scientists think the mussels' reduced growth rate may reflect the river's return to a more 'natural' state. Since 1964, levels of nitrate and phosphate in the river water have fallen due to tighter regulation of sewage treatment. A reduction in these nutrients would reduce the growth of algae, limiting the food available to the mussels.

Mussel species are threatened globally. The scientists say that regular population surveys of key species, like this one, are essential to tracking the health of rivers and guiding their management.

To ensure the survey was an exact replica of the original, Ollard contacted Christina Negus -- who had done her survey while a researcher at the University of Reading in the sixties. Negus, who is no longer a scientist, shared details of the methods and equipment she had used. Her report, published in 1966, continues to be cited extensively as evidence of the major contribution mussels make to ecosystem functioning in rivers.

Story Source:

Materials provided by University of Cambridge. Original written by Charis Goodyear. The original text of this story is licensed under a Creative Commons License. Note: Content may be edited for style and length.

#Environment | https://sciencespies.com/environment/mussel-survey-reveals-alarming-degradation-of-river-thames-ecosystem-since-the-1960s/

Adventurous bird personalities can help population cope with climate change

The areas in the Wadden Sea where red knots, plump migratory birds, spend the winter are under pressure. The Wadden Sea is changing due to human influences such as mining for gas, tourism and due to sea level rise. Researcher Selin Ersoy, ecologist at the Royal Netherlands Institute for Sea Research (NIOZ) studied how 'personalities' of individual red knots differ and affect the way they search for food. Individuals that are fast explorers and take the risk to forage in different areas, also eat different food. This could make the total population of red knots a lot more resilient while their environment is changing. Red knots could copy the food-gathering behaviour of adventurous peers who succeed in new places. "Differences in character between red knots seem to be an important ingredient for the resilience of the whole group," said Ersoy. For the first time, her study shows that behaviour that was observed in experimental settings corresponds with actual real-life behavioural strategies in the wild, on the mudflats of the Wadden Sea. This week Selin Ersoy defended her Phd thesis at the Groningen University.

Animals also have personalities

Red knots of all ages and sexes show behavioural traits. These remain mostly unchanged over time but differ across individuals. Some individuals are more adventurous and show more exploratory behaviours a in new environment than others. Other individuals take less risks and hardly dare to move around in a new environment. These 'personalities' have ecological and evolutionary consequences, but to what extent is largely unknown, because few studies have investigated this in the field.

During her PhD research Selin Ersoy has developed a new way of identifying the variation in personality between individual red knots. She wanted to know if the behaviour in experimental settings could be extrapolated to a larger and more complex natural setting, and how individual differences develop.

"With our new method that allowed studying animal personality in the wild, we found that red knots develop their personality probably through the experience that they get when growing up ," says Ersoy. "After growing up, adults stick with exploratory behaviours. They seem to be like character types in humans."

Explorers eat higher quality food

It was even possible for Ersoy and her colleagues to predict a suit of other behaviours in the wild. For instance, variation in explorative personality type (i.e., slow vs. fast explorer) predicts foraging tactics and dietary choice in the wild. Fast explorers use more visual foraging and eat soft prey such as shrimp or worms, while slow explorers use tactile foraging and feed on hard-shelled prey such as cockles. This is a new explanation for variation in foraging niche specialisation between individuals in the same population.

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Exploratory behaviour also relates to variation in movement across the landscape and over time. Ersoy: "We were amazed to see that slow and fast explorers have clearly different movement patterns during the night, while at day they moved more or less the same way. These different individuals even have different arrival times from migration. Fast explorers arrive to the Wadden Sea later than the slower explorers." Ersoy and her colleagues want to study next where they stay in the meantime. Maybe these red knots take more time to care for their youngs in the Arctic.

The whole group benefits

"We found striking differences in feeding and movement patterns between slow and fast exploring red knots. This suggests that fast explorers might provide foraging information and new foraging opportunities for entire populations," says Ersoy. "Such new opportunities are important because red knots face pressures from human impact on their coastal wintering habitats, directly related to availability of food. Fast explorers can help the entire population to cope with environmental change."

Gap closed between controlled experiments and real Wadden Sea

The goal of determining behaviour in experimental setups is to understand the mechanisms behind the behaviour in the wild. Selin Ersoy's study fills a critical gap between experimental research on wild animals in controlled environments and observed behaviour in the wild.

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"It's a first step. We need to do similar personality research on other animals and on other natural habitats," says Ersoy. "We want to know if personalities work the same in other species and situations."

Tracking movements of guillemots with tiny transmitters

Researchers like Selin Ersoy track birds using ultra-small radio transmitters placed on their backs during the summer months. Birds are not bothered by them. Those transmitters send out unique signals. These are received by antennas scattered throughout the Wadden Sea.

Reverse GPS

WATLAS is a new system that makes use of so-called 'reverse-GPS'. The tiny transmitters that are temporarily attached to birds transmit a signal of their own. That signal is received by fixed receiving stations in and around the Wadden Sea. Due to the tiny differences in the time of arrival of the signal between different receivers, the position of the animal-with-transmitter is calculated to the accuracy of a few meters, from second to second.

Thanks to WATLAS, researchers can watch a migratory bird such as the red knot move back and forth with low and high tide very precisely in search of food. Because many birds can be fitted with the relatively inexpensive transmitters at the same time, researchers can now see interactions between different animals happening from the comfort of their office chairs.

#Nature | https://sciencespies.com/nature/adventurous-bird-personalities-can-help-population-cope-with-climate-change/

Animals are key to restoring the world's forests

As UN climate talks close in Egypt and biodiversity talks begin in Montreal, attention is on forest restoration as a solution to the twin evils roiling our planet. Forests soak up atmospheric carbon dioxide and simultaneously create habitat for organisms. So far, efforts to help forests bounce back from deforestation have typically focused on increasing one thing -- trees -- over anything else. But a new report uncovers a powerful, yet largely overlooked, driver of forest recovery: animals. The study by an international team from the Max Planck Institute of Animal Behavior, Yale School of the Environment, the New York Botanical Garden, and the Smithsonian Tropical Research Institute examined a series of regenerating forests in central Panama spanning 20 to 100 years post-abandonment. The unique long-term data set revealed that animals, by carrying a wide variety of seeds into deforested areas, are key to the recovery of tree species richness and abundance to old-growth levels after only 40-70 years of regrowth. The article, published in Philosophical Transactions of the Royal Society B, is part of a theme issue focused on forest landscape restoration as part of the UN Decade on Ecosystem Restoration.

"Animals are our greatest allies in reforestation," says Daisy Dent, a tropical ecologist from MPI-AB and the study's senior author. "Our study prompts a rethink of reforestation efforts to be about more than just establishing plant communities."

The report also notes that situating regenerating forests near patches of old growth, and reducing hunting, encourages animals to colonize and establish. "We show that considering the wider ecosystem, as well as features of the landscape, improves restoration efforts," says Sergio Estrada-Villegas, a biologist now at Universidad del Rosario (Bogotá, Colombia) and the study's first author.

Seed dispersal by animals is key to forest expansion. In the tropics, over 80% of tree species can be dispersed by animals, which transport seeds throughout the landscape. Despite this, forest restoration efforts continue to focus on increasing tree cover rather than reestablishing the animal-plant interactions that underpin ecosystem function. "Figuring out how animals contribute to reforestation is prohibitively hard because you need detailed information about which animals eat which plants," says Estrada-Villegas.

The forest at the Barro Colorado Nature Monument (BCNM), in the Panama Canal, offers a unique solution to this problem. In one of the best studied tropical forests in the world, generations of scientists at have documented frugivore interactions to understand which groups of animals disperse which tree species.

In the present study, the team led by Estrada-Villegas and Dent examined this unique long-term dataset to determine the proportion of plants dispersed by four groups of animals -- flightless mammals, large birds, small birds, and bats -- and how this proportion changed over a century of natural restoration.

Their results offer the most detailed data of animal seed dispersal recovery across the longest timeframe of natural restoration. "Most studies examine the first 30 years of succession, but our data spanning 100 years gives us a rare glimpse into what happens in the late phase of restoration," says Dent.

The study found that young regenerating forests were made up mostly of trees dispersed by small birds. But as the forest aged, trees dispersed by larger birds increased. Surprisingly, however, the majority of plants were dispersed by terrestrial mammals across all forest ages -- from 20 years old to old growth. "This result is quite unusual for post-agricultural regenerating forests," says Dent. "It is likely that the presence of large tracts of preserved forests near our secondary stands, coupled with low hunting, has allowed the mammal populations to thrive and to bring an influx of seeds from neighboring patches."

Says Estrada-Villegas: "We hope this information can help practitioners to structure their restoration practices by enabling frugivorous species to help the restoration process and speed up forest recovery."

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Materials provided by Max-Planck-Gesellschaft. Note: Content may be edited for style and length.

#Nature | https://sciencespies.com/nature/animals-are-key-to-restoring-the-worlds-forests/

Unprecedented levels of insects damaging plants

Insects today are causing unprecedented levels of damage to plants, even as insect numbers decline, according to new research led by University of Wyoming scientists.

The first-of-its-kind study compares insect herbivore damage of modern-era plants with that of fossilized leaves from as far back as the Late Cretaceous period, nearly 67 million years ago. The findings appear in the  journal Proceedings of the National Academy of Sciences.

"Our work bridges the gap between those who use fossils to study plant-insect interactions over deep time and those who study such interactions in a modern context with fresh leaf material," says the lead researcher, UW Ph.D. graduate Lauren Azevedo-Schmidt, now a postdoctoral research associate at the University of Maine. "The difference in insect damage between the modern era and the fossilized record is striking."

Azevedo-Schmidt conducted the research along with UW Department of Botany and Department of Geology and Geophysics Professor Ellen Currano, and Assistant Professor Emily Meineke of the University of California-Davis.

The study examined fossilized leaves with insect feeding damage from the Late Cretaceous through the Pleistocene era, a little over 2 million years ago, and compared them with leaves collected by Azevedo-Schmidt from three modern forests. The detailed research looked at different types of damage caused by insects, finding marked increases in all recent damage compared to the fossil record.

"Our results demonstrate that plants in the modern era are experiencing unprecedented levels of insect damage, despite widespread insect declines," wrote the scientists, who suggest that the disparity can be explained by human activity.

More research is necessary to determine the precise causes of increased insect damage to plants, but the scientists say a warming climate, urbanization and introduction of invasive species likely have had a major impact.

"We hypothesize that humans have influenced (insect) damage frequencies and diversities within modern forests, with the most human impact occurring after the Industrial Revolution," the researchers wrote. "Consistent with this hypothesis, herbarium specimens from the early 2000s were 23 percent more likely to have insect damage than specimens collected in the early 1900s, a pattern that has been linked to climate warming."

But climate change doesn't fully explain the increase in insect damage, they say.

"This research suggests that the strength of human influence on plant-insect interactions is not controlled by climate change alone but, rather, the way in which humans interact with the terrestrial landscape," the researchers concluded.

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Materials provided by University of Wyoming. Note: Content may be edited for style and length.

#Nature | https://sciencespies.com/nature/unprecedented-levels-of-insects-damaging-plants/