The supermassive black hole lurking at the centre of our Milky Way galaxy is not as dormant as had been thought, a new study shows.
The slumbering giant woke up around 200 years ago to gobble up some nearby cosmic objects before going back to sleep, according to the study published in the journal Nature on Wednesday.
NASA's IXPE space observatory spotted an x-ray echo of this powerful resurgence of activity, the researchers said.
The supermassive black hole Sagittarius A* -- abbreviated to Sgr A* -- is four million times more massive than the Sun. It sits 27,000 light years from Earth at the centre of the Milky Way's spiral.
Last year astronomers revealed the first-ever image of the black hole -- or rather, the glowing ring of gas that surrounds its blackness.
Sgr A* has "always been seen as a dormant black hole," said Frederic Marin, a researcher at France's Strasbourg Astronomical Observatory and the study's first author.
Most supermassive black holes squatting at the middle of their galaxies go dormant after swallowing up all the nearby matter.
"Imagine a bear going into hibernation after devouring everything around it," Marin told AFP.
But the international team of researchers discovered that at around the end of the 19th century, Sgr A* came out of its slumber and consumed any gas and dust unlucky enough to be within its reach.
The feeding frenzy lasted from several months to a year, before the beast went back into hibernation.
Million times brighter
When it was active, the black hole was "at least a million times brighter than it is today," Marin said.
Its awakening was noticable because nearby galactic molecular clouds started giving off vastly more x-ray light.
The surge in x-ray light was as "if a single glow-worm hidden in a forest suddenly became as bright as the Sun," French research agency CNRS said in a statement.
Astronomers using NASA's IXPE (Imaging X-ray Polarimetry Explorer) space observatory managed to track the x-ray light and found that it pointed straight back at Sgr A*.
The black hole "emitted an echo of its past activity, which we managed to observe for the first time," Marin said.
The pull of gravity from black holes is so intense that nothing can escape, including light.
But when matter is sucked beyond the black hole's final boundary, known as the event horizon, it emits a massive amount of heat and light before disappearing into the darkness.
Exactly what caused Sgr A* to briefly emerge from its dormant state remains unclear. Could a star or cloud of gas and dust have ventured too close?
The astronomers hope that further observations from the IXPE observatory will help them better understand what happened -- and perhaps reveal more about the origin of supermassive black holes, which remains shrouded in mystery.
Happy solstice everyone! The mid-year solstice in 2023 falls at 2:58 pm UTC on 21 June (or, in more advanced time zones like the one I’m writing from, in the early hours of 22 June).
Depending on where you are reading this, this will either be your winter solstice (for those in the southern hemisphere) or the summer solstice (for our northern readers).
But what is the solstice? What does it mean for our day-to-day lives? Well the answer all boils down to orbits – the way Earth whirls and wobbles as it wends its way around the Sun.
The seasons: the result of a moving platform
Earth is a moving platform – orbiting the Sun in a little more than 365 days. Despite our incredible orbital speed (around 30 kilometers per second), we don’t feel this motion. Instead, it appears to us as though the Sun is moving through the year.
Imagine for a moment you could remove Earth’s atmosphere, revealing the background stars at the same time as the Sun. Those stars, incredibly distant, rise and set every 23 hours, 56 minutes and 4 seconds - the true rotation period of Earth.
The Sun, though, rises and sets roughly every 24 hours – making the “solar day” 3 minutes and 56 seconds longer than Earth’s true rotation period.
That difference is the result of the Sun’s apparent motion against the background stars. From our imaginary airless Earth, we would see the Sun gradually sliding through the constellations of the zodiac, making one full lap of the sky in one year.
But things are a little more complicated. You see, our moving platform is tipped over, tilted on its side by about 23.5 degrees.
As we move around the Sun, our planet alternately tilts one hemisphere towards our star, then away again. This is the cause of the seasons.
The length of the day changes over the year due to the slight tilt in the Earth’s axis. Bureau of Meteorology
When your hemisphere is tilted towards the Sun, you have summer – long days, with the noonday Sun high in the sky. Six months later, when you are tilted away, you have winter – the noonday Sun is low, days are shorter, and there is a chill in the air.
Between those extremes, the Sun gradually drifts north and south. At the extremes of its motion, it would be overhead from 23.5° north of the Equator (northern hemisphere midsummer) or 23.5° south (southern midsummer).
In total, then, the Sun’s motion moves it between two extremes some 47° apart. Low in the sky in winter, and high in summer.
So what are the solstices?
The two solstices are the points at which the Sun is either the farthest north in the sky (which is what we have today), or at its most southerly location.
A map of the entire night sky, like a map of the Earth, showing (in red) the path followed by the Sun through the course of the year - a path known as the ‘ecliptic’. Pablo Carlos Budassi/Wikipedia
When the Sun is farthest north in the sky, it will appear lowest in the sky at noon from locations in the southern hemisphere. This also means the shortest period of daylight of the calendar year.
For the northern hemisphere, the situation is reversed – the summer solstice places the noonday Sun high in the sky, with the longest period of daylight of the year.
In six months’ time, on December 22 this year, we will have the other solstice – marking the point at which the Sun is at its most southerly point in the sky. That will bring with it the longest day for those in the southern hemisphere, and the shortest for those in the north.
It’s easy to find out when the Sun will rise and set at your location. Many websites provide this information these days - here, for example, is all that information for my home town – Toowoomba, in southeast Queensland.
Defining the seasons: climate or cosmology?
To an astronomer, and to many people around the world, today marks the change of the seasons. In the southern hemisphere, it is the first day of winter. In the north, the first of summer.
Strangely, the solstices are also known as midsummer’s day and midwinter’s day – which leads to the strange idea that winter starts at midwinter!
By this astronomical definition for the seasons, summer runs from midsummer to the autumnal equinox (when the Sun crosses the Equator). Autumn runs from that equinox to midwinter’s day. Winter goes from midwinter to the spring equinox, and spring goes from the spring equinox through to midsummer.
In Australia, however, most people are familiar with seasons beginning on the first day of the months of March, June, September and December.
The reason is down to how our climate behaves. In a simple universe, one would expect the longest day to be the hottest (with most time for the Sun to heat the Earth) and the shortest day to be the coldest (the most hours of darkness for things to cool down).
However, things are somewhat more complex. The atmosphere, the ground, and particularly the oceans, take a long time to heat up and to cool down. The result? The warmest time of the year for many places (but not all!) comes a few weeks after midsummer.
While the days are getting shorter, the ocean, ground and air continue to warm up. Similarly, the coldest time in winter is usually a few weeks after midwinter.
Our concept of summer (rather than the astronomer’s definition) is built around this. We think of the middle of summer being the hottest time of year, and the middle of winter being the coldest.
There’s always another secret
Before I leave you to enjoy the rest of the year’s shortest (or longest) day, there’s one extra cool fact about the seasons that most people don’t appreciate. We imagine the seasons are of equal length - three months of each, in a 12-month year.
But we forget. Not all months are alike. Some are shorter than others (poor February).
Look at a calendar, and add up the days in each astronomical season, and you find something surprising.
The southern hemisphere summer (northern winter), from December 22 to March 21, lasts just 89 days. The southern winter (northern summer), by contrast, is almost 94 days long!
The southern autumn (March to June) is almost 93 days long, while the northern autumn (September to December) is only 90 days.
The reason behind these variations is, once again, all down to Earth’s orbit. As we move around the Sun, the distance to our star varies slightly.
Sometimes, we are closer to our star, and Earth moves faster in its orbit. At other times, we are more distant, and move slower.
In just a couple of weeks time, on July 7, Earth will reach its farthest point from the Sun, which astronomers call “aphelion”. On that date, we will be more than 152 million kilometers from our star.
Six months later, on January 3 2024, we will be at our closest to the Sun – “perihelion” – just over 147 million kilometers distant.
This really highlights one of the beauties of astronomy. Simply put – there’s always another secret – the deeper you look into something, the more beautiful complexity you will find.
When a hurricane hits land, the destruction can be visible for years or even decades. Less obvious, but also powerful, is the effect hurricanes have on the oceans.
In a new study, we show through real-time measurements that hurricanes don’t just churn water at the surface. They can also push heat deep into the ocean in ways that can lock it up for years and ultimately affect regions far from the storm.
What we discovered is that hurricanes ultimately help warm the ocean, too, by enhancing its ability to absorb and store heat. And that can have far-reaching consequences.
When hurricanes mix heat into the ocean, that heat doesn’t just resurface in the same place. We showed how underwater waves produced by the storm can push the heat roughly four times deeper than mixing alone, sending it to a depth where the heat is trapped far from the surface. From there, deep sea currents can transport it thousands of miles. A hurricane that travels across the western Pacific Ocean and hits the Philippines could end up supplying warm water that heats up the coast of Ecuador years later.
At sea, looking for typhoons
For two months in the fall of 2018, we lived aboard the research vessel Thomas G. Thompson to record how the Philippine Sea responded to changing weather patterns. As oceanscientists, we study turbulent mixing in the ocean and hurricanes and other tropical storms that generate this turbulence.
Skies were clear and winds were calm during the first half of our experiment. But in the second half, three major typhoons – as hurricanes are known in this part of the world – stirred up the ocean.
Microstructure profilers are used to measure ocean turbulence. This one is designed and built by the Ocean Mixing Group at Oregon State University. Sally Warner
That shift allowed us to directly compare the ocean’s motions with and without the influence of the storms. In particular, we were interested in learning how turbulence below the ocean surface was helping transfer heat down into the deep ocean.
We measure ocean turbulence with an instrument called a microstructure profiler, which free-falls nearly 1,000 feet (300 meters) and uses a probe similar to a phonograph needle to measure turbulent motions of the water.
What happens when a hurricane comes through
Imagine the tropical ocean before a hurricane passes over it. At the surface is a layer of warm water, warmer than 80 degrees Fahrenheit (27 degrees Celsius), that is heated by the sun and extends roughly 160 feet (50 meters) below the surface. Below it are layers of colder water.
The temperature difference between the layers keeps the waters separated and virtually unable to affect each other. You can think of it like the division between the oil and vinegar in an unshaken bottle of salad dressing.
As a hurricane passes over the tropical ocean, its strong winds help stir the boundaries between the water layers, much like someone shaking the bottle of salad dressing. In the process, cold deep water is mixed up from below and warm surface water is mixed downward. This causes surface temperatures to cool, allowing the ocean to absorb heat more efficiently than usual in the days after a hurricane.
For over two decades, scientists have debated whether the warm waters that are mixed downward by hurricanes could heat ocean currents and thereby shape global climate patterns. At the heart of this question was whether hurricanes could pump heat deep enough so that it stays in the ocean for years.
These illustrations show what happens to ocean heat before, during, after and many months after a hurricane passes over the ocean. Sally Warner, CC BY-ND
By analyzing subsurface ocean measurements taken before and after three hurricanes, we found that underwater waves transport heat roughly four times deeper into the ocean than direct mixing during the hurricane. These waves, which are generated by the hurricane itself, transport the heat deep enough that it cannot be easily released back into the atmosphere.
Implications of heat in the deep ocean
Once this heat is picked up by large-scale ocean currents, it can be transported to distant parts of the ocean.
The heat injected by the typhoons we studied in the Philippine Sea may have flowed to the coasts of Ecuador or California, following current patterns that carry water from west to east across the equatorial Pacific.
At this point, the heat may be mixed back up to the surface by a combination of shoaling currents, upwelling and turbulent mixing. Once the heat is close to the surface again, it can warm the local climate and affect ecosystems.
For instance, coral reefs are particularly sensitive to extended periods of heat stress. El Niño events are the typical culprit behind coral bleaching in Ecuador, but the excess heat from the hurricanes that we observed may contribute to stressed reefs and bleached coral far from where the storms appeared.
Coral reefs are essential habitat for fish and other sea life, but they are threatened by rising ocean temperatures. James Watt via NOAA
It is also possible that the excess heat from hurricanes stays within the ocean for decades or more without returning to the surface. This would actually have a mitigating impact on climate change.
As hurricanes redistribute heat from the ocean surface to greater depths, they can help to slow down warming of the Earth’s atmosphere by keeping the heat sequestered in the ocean.
Scientists have long thought of hurricanes as extreme events fueled by ocean heat and shaped by the Earth’s climate. Our findings, published in the Proceedings of the National Academy of Sciences, add a new dimension to this problem by showing that the interactions go both ways — hurricanes themselves have the ability to heat up the ocean and shape the Earth’s climate.
Tiny pieces of plastic have been found littered throughout human bodies, trapped in our lungs and laced through our blood, but the long-term health effects of this exposure remain unclear.
Every day humans ingest, inhale or otherwise come in contact with microplastics, plastic pollution less than five millimetres (0.2 inches) in diameter that is mostly invisible to the naked eye.
Microplastics have been found most everywhere on Earth, from the deepest oceans to the highest mountains, as well as in the air, water, soil and food chain.
But in the last couple of years scientists have discovered microplastics not just throughout nature but also throughout human bodies, detecting it in lungs, livers -- even in placentas.
Last year a Dutch study became the first to identify microplastics in human blood.
While scientists have urged caution due to the study's small sample size, the presence of microplastics could suggest it is being transported through the bloodstream into organs.
But for now, the data remain incomplete on the health effects of microplastics, a complex cocktail of polymers and chemicals that could smuggle in other contaminants in what is called the "Trojan Horse" effect.
- 'Insidious' -
Xavier Coumoul, a toxicologist at French medical research institute INSERM, told AFP that there has been "more and more research" in the area over the last decade.
But he said that research had been late to get started because -- similar to global warming -- the "insidious changes" crept up so slowly.
"We do not know whether our level of exposure will lead to chronic or acute illnesses in the long term -- but we can legitimately ask the question," he said.
Research has shown that microplastics have a range of detrimental effects on the health of animals, including an increase in inflammation, oxidative stress and damage to cells.
"Both in human and mice lung tissues, we have seen an inhibitory effect on development after putting plastic fibres inside organoids, mini-lungs grown" from stem cells, said Barbro Melgert, a respiratory immunologist at the University of Groningen in the Netherlands.
"This effect seemed not to be caused by the plastic itself, but by something leaking from the (plastic particles), some chemicals added," she said.
"But we don't know exactly what chemical was involved," she said. "It's very difficult to find out, especially with low quantities."
Indeed, the roles that the shape, size and type of microplastic -- as well as additives -- remain poorly understood. But researchers are working on it.
Last week, a study in the journal Physics of Fluid modelled how different sizes of inhaled microplastics rattled through human airways, finding that they tended to collect in the nasal cavity or in the back of the throat.
- Tipping point? -
It is also unclear how much microplastic individual people are exposed to.
"We don't really know how much microplastics we breathe, there's not a lot of studies," Melgert said, adding that research over longer time periods was needed.
The World Wildlife Fund made headlines in 2019 by estimating that people ingest around five grams of plastic a week, the equivalent of a credit card.
The methodology and findings of the study the WWF was citing have been contested, and other research has indicated a lower level of individual exposure.
But experts are still sounding the alarm.
Coumoul compared microplastics to pesticides, saying "it has sometimes taken a long time to identify the long-term risk to humans".
"Let's try to prevent a time bomb," Melgert said.
And an even greater tidal wave of plastic looms on the horizon.
On current trends, annual production of fossil-fuel plastic will nearly triple by 2060 to 1.2 billion tonnes.
Melgert warned that humanity's ever-increasing production of plastic means that we could soon "pass a critical limit" for human exposure.
Earlier this month, there was some rare goods news in the fight against plastic pollution.
After five days of gruelling talks, 175 nations gathered in Paris agreed to reveal the first draft of a much-anticipated plastic pollution treaty by the end of November.
For now, experts recommend that people limit their exposure to microplastics by ventilating their homes, not eating out of plastic containers and avoiding synthetic textiles such as polyester.
When faced with difficult choices, we often rank the alternatives to see how they stack up. This approach is ubiquitous, used from major business and policy decisions, through to personal choices such as the selection of a university course, place to live, or political voting preference.
Typically, criteria are identified and each one is “weighted” according to importance. The options are then scored against each criterion and the weightings applied. But this common approach is frequently flawed and not as rational as it first seems.
Decision-making usually involves choosing from a limited range of options. When there is only one criterion to consider, such as cost, the decision is straightforward. Normally, however, there are pros and cons to balance up for each option. A process known as multi-criteria decision analysis is often used to weigh alternatives in this way.
There are many variants, but the weighted-sum method is the most common. This technique appears superficially simple, logical and intuitive. Typically, the decision-maker starts by eliminating any options that fail to deliver one or more essential requirements, which are termed the “needs”.
The second stage involves sorting the remaining options into an order according to preference. This preference order is based on how well the options satisfy the other requirements, which are termed the “wants”. The needs must be satisfied, whereas the wants are attributes to maximize. Eliminating options that fail to meet the needs is straightforward, but combining the wants is more complicated.
To evaluate options against the wants, the decision-maker draws up a table in which column headings represent the different alternatives and row headings represent the wants. Scores are placed in the cells of the table to represent the performance of each option against each want. Some wants are more important than others, so each one is given an importance weighting.
Typically, the scores and weightings, or “weights”, are both chosen on a scale from zero to ten. Each score is then multiplied by its corresponding weight and additional columns can be inserted in the table for this purpose. The weighted scores are then added together for each option. Finally, the options are ranked according to their total weighted score.
A variant is the weighted-product method, where the weighted scores for each option are multiplied together, rather than added together. It requires all values to be at least one. This method favors good all-round performance, whereas the weighted-sum method is more forgiving of wide variations in performance.
Flaws in the conventional approach
A weakness in most of these multi-criteria decision analyses is their dependence on number values to express ideas that depend on a human evaluation – in other words, they are “qualitative”.
Aside from those difficulties, the straightforward multiplication of a score by an importance weighting has inherent pitfalls if a simple scale like zero to ten is used. Where a want is considered important – has a high importance weighting – and a candidate performs well with respect to that want, the weighted score will be high, as expected.
Where a want is considered less important and an option performs poorly with respect to that want, the method will give that option a low-weighted score. However, since the want in question has a low importance weighting, the option should not be penalized harshly and should remain in contention.
Ideally, the lowest weighted scores ought to be those ascribed to options with a low score against a highly weighted want. They should not be given to options that score low against a want that has a low weighting and is therefore inconsequential. So, although the standard approach works for identifying the best options, it is poor at ranking the alternatives and it gives a false impression of the worst options.
Consider such an approach being used to allocate funding, based on applications for a grant. Rival bids might be scored against wants such as innovation, quality, timeliness and value-for-money, each of which is weighted according to importance. The smallest awards ought to be given to the bids with the lowest scores against the most important criteria. Instead, the bids ranked bottom are those with low scores against criteria that are least important.
A better approach
These problems can be addressed by using a scoring scale that includes negative values. The alternative inference mechanism (AIM) method, makes the necessary adjustments while keeping an intuitive range of scores, such as zero to ten.
AIM recognizes that the worst candidates are those with low scores against wants that have high importance weightings. On the other hand, candidates that score poorly against an unimportant want are not severely disadvantaged.
The chart below contrasts AIM with the conventional approach. The two methods agree on the best options, which are the green ones clustered at the top-right. However, the worst options in red or orange are at the bottom-left using the conventional approach, and at the bottom-right with AIM.
A comparison between conventional scoring (top) and the AIM approach (bottom). Adrian Hopgood, Author provided
The conventional approach has a row of zeros across the bottom, as it ranks candidates equally if they score zero against a want, regardless of its importance. Similarly, it has a column of zeros up the left side, as it penalizes all candidates against unimportant criteria, regardless of their score. In contrast, AIM has a lot of yellow on the left side, indicating that unimportant scores are neither good nor bad – a much more logical and a rational basis for sound decision-making.
Multi-criteria decision analysis can be an excellent tool for choosing between alternative options, but understanding the weighting mechanism is vital.
AIM has shown the value of probing a little deeper into the meaning of the numbers. With greater awareness of rational models like AIM, we could make better decisions in all aspects of our lives.
Fish are the most diverse group of vertebrates, ranging from tiny gobies and zebrafish to gigantic tunas and whale sharks. They provide vital sustenance to billions of people worldwide via fisheries and aquaculture, and are critical parts of aquatic ecosystems.
But fish around the world are getting smaller as their habitats get warmer. For example, important commercial fish species in the North Sea have declined in size by around 16% in the 40 years to 2008, while the water temperature increased by 1–2℃. This “shrinking” trend is forecasted to significantly exacerbate the impacts of global warming on marine ecosystems.
The link between warmer water and smaller size is well known, but poorly understood. Our experiments keeping fish in warmer water offer some crucial clues – and may help us learn how to prepare for a warmer future with smaller fish.
The temperature–size rule
Fisheries are a potential confounding factor when studying the effect of warmer waters on fish, because fisheries often target large fish. Removing these larger fish from the population benefits the survival of fish that mature quickly and reproduce at a younger age, when they are smaller.
This trait of maturing early can be passed through fish generations. Indeed, it can lead to a phenomenon known as “fisheries-induced evolution”, where the exploited species tends to decrease in size over time.
How do we tell the difference between the impacts of climate warming and those of fisheries?
One way is to examine the body size trends in fish species that are not targeted by fisheries. Several fish species in French rivers, for example, are not exploited by fisheries but have decreased in size over several decades while their environment has grown warmer.
Fishing can reduce fish sizes, but even fish populations largely unaffected by fisheries appear to be shrinking. Sebastian Pena Lambarri / Unsplash
Another way is to examine fish under controlled conditions, by manipulating water temperature and studying the impact on fish size. Such experiments have shown that fish do indeed end up smaller in body size when kept under warm conditions, and the trend is so common it has been given a name: the “temperature–size rule”.
So shrinking fish means each fish will have fewer offspring, and more fish being caught. This is likely to have substantial ecological and commercial ramifications.
Supply and demand
Warmer water means smaller fish, but why?
The most popular current theories suggest the cause is due to a mismatch between how much oxygen a fish needs (to sustain its body’s metabolism) and how much it can get (via its gills).
The argument is that fish gills do not grow at the same pace as the rest of their bodies. Once a fish reaches a certain body size, its gills can only supply enough oxygen to keep its body running – there is no oxygen left over for growth.
What does this have to do with warming? The next step of the argument says fish use more oxygen in warmer water – but their gills don’t get any bigger. So fish reach the limit of their growth at a smaller size, leading to the temperature–size rule.
This “oxygen mismatch” theory has sparked heated debate among global scientists, largely because insufficient data exist to confirm or refute it.
Oxygen supply can keep up with demand
To get some data, we have carried out long-term experiments keeping fish under warmer water conditions than normal. We also tried providing extra oxygen, to see if it benefited their growth.
We have regularly taken metabolic measurements, and quantified the gill surface area of the fish to understand how well they can transport oxygen from the water into the body.
Fish need more oxygen when they live in warmer waters – but research shows their gills are capable of keeping up with the increase in demand. Paco Joss / Unsplash
Our results show the “oxygen mismatch” theory doesn’t hold up. While the metabolism of fish does increase with warming of the water, we found the gills grow sufficiently to keep up with the increased oxygen demand as fish increase in size.
So, why then are fish shrinking as the climate warms?
Is reproduction the key?
We know that fish tend to grow faster in warmer conditions and reach reproductive maturity at an earlier age and smaller size. It is possible that once fish start reproducing, energy is channelled into reproduction rather than further growth.
Evidence for this comes from a population of fish living in a Swedish lagoon that gives us an eye to a warmer future, as the lagoon receives warm (non-contaminated) water from a nearby nuclear power plant.
Fish in the warm lagoon grow faster and reach reproductive maturity earlier, then they tend to die at a younger age and at a smaller body size than their counterparts living in adjacent, cooler waterways. “Live fast, die young”, as the saying goes.
While this idea seems to be broadly applicable, some conflicting findings point to the need for more focused research attention.
Fish can’t keep shrinking forever
As our understanding of the relationship between temperature and fish size increases, we would also like to know whether we can do anything about it.
In our latest research, we explored differences in growth rates between individual fish of the same species.
One thing we wanted to know was whether particular physiological traits may allow some individuals to get around the temperature–size rule and be impacted less by climate warming. We found there is significant variability across individual fish, but we don’t know how this variability could be harnessed to future-proof fish populations.
As our work continues, we also look to the future and think about the ramifications to fish and the industries that rely on them.
Fish cannot keep shrinking forever. There is a minimum size that each species must reach in order to maintain a viable population.
If species reach their specific thermal limits in particular locations, they will not be able to reproduce and they will cease to exist in those locations. If their entire habitat range becomes too warm, the species will become extinct.
These considerations of smaller fish and shifting thermal habitats will be critical for the sustainability of fisheries and aquaculture industries as we continue into a future with a warmer, more extreme climate. Our efforts to quantify and forecast the impacts will help resource managers and industries prepare for climate-linked disruption.
Scientists have used stem cells to create structures that resemble human embryos in the lab, in a first that has prompted calls for stricter regulation in the rapidly advancing field.
Several different labs around the world have released pre-print studies in the past seven days describing their research, which experts said should be treated with caution as the research has not yet been peer-reviewed.
The labs used different techniques to encourage human embryonic stem cells, which can become any type of cell, to self-assemble into a structure that resembles an embryo -- without needing sperm, an egg or fertilization.
The aim is to give scientists a model with which to study human embryos in ways never before possible because of ethical concerns, in the hopes of gaining new insight into the causes of birth defects, genetic disorders, infertility and other problems during pregnancy.
The first announcement was last Wednesday, when Magdalena Zernicka-Goetz of Cambridge University and the California Institute of Technology described her team's work at the International Society for Stem Cell Research's annual meeting in Boston.
Her presentation was first reported by The Guardian newspaper.
On Thursday, the team of Jacob Hanna at the Weizmann Institute of Science in Israel published a pre-print study detailing their own work on stem cell-based human embryo models.
The Zernicka-Goetz team then quickly published a pre-print of their own, giving more information. Other labs based in China and the United States followed suit, releasing pre-prints late last week.
Researchers have pushed back against media reports calling the clumps of cells "synthetic embryos," saying that they are neither strictly synthetic, having grown from stem cells, nor should they be considered embryos.
- 'Almost uncanny' -
The flurry of data has highlighted the highly competitive nature of research in this field.
Within a few weeks of each other in August last year, both the Zernicka-Goetz and Hanna teams published papers about their work creating the first embryo-like structures using stem cells from mice.
Both teams told AFP that their new studies had been accepted by prestigious peer-reviewed journals -- and that they had presented their work at conferences months before the recent media attention.
Hanna rejected the idea that either team was "first", saying they had achieved quite different feats.
He told AFP that his models had a "placenta, a yolk sac, amniotic cavity" and other embryo features that he said the Zernicka-Goetz structures lacked.
Other researchers seemed to agree that Hanna's models were more advanced, also praising his team for using only chemical and not genetic modifications to coax the cells into embryo-like structures.
"The similarity (of Hanna's model) to the natural embryo is remarkable, almost uncanny," said Jesse Veenvliet, a researcher at Germany's Max Planck Institute of Molecular Cell Biology and Genetics.
Darius Widera, an expert in stem cell biology at the UK's University of Reading, told AFP that it was best to wait for peer review before comparing the research.
But "the impact of both studies is immense", he added.
"We should try to avoid unhealthy hype since this technology is at an early stage -- but already, new guidelines are going to be needed."
Inside the 'black box'?
Both labs said they had developed their embryo models for 14 days, the legal limit for growing human embryos in the lab in many countries.
After 14 days embryos start organizing cells to form organs including the brain, a period called the "black box" because little is known about human embryos beyond that point.
Regulations for research in this area differ between countries but most apply to embryos that have been fertilized -- a loophole the new embryo-like models slip through.
Cambridge University said on Friday it had launched a project to develop the first governance framework for stem cell-based human embryo models in the UK.
The scientists involved have emphasized that they are not intending to implant their embryo models into a human womb -- and that even if this was done, it would not lead to a baby.
An embryo model implanted in a female macaque as part of earlier research did induce some signs of pregnancy, but did not survive, Widera said.
James Briscoe of Britain's Francis Crick Institute called for researchers to "proceed cautiously, carefully and transparently".
"The danger is that missteps or unjustified claims will have a chilling effect on the public and policymakers, this would be a major setback for the field."
By Gloria Dickie (Reuters) - Glaciers in Asia’s Hindu Kush Himalaya could lose up to 75% of their volume by century’s end due to global warming, causing both dangerous flooding and water shortages for the 240 million people who live in the mountainous region, according to a new report. A team of international scientists has found that ice loss in the region, home to the famous peaks of Everest and K2, is speeding up. During the 2010s, the glaciers shed ice as much as 65% faster than they had in the preceding decade, according to the assessment by the Kathmandu-based International Centre for In...
Over the past eight years, I have been asked to submit astronomical evidence for court cases all over Australia.
Normally when we think of evidence in court, we think of eyewitnesses, DNA or police reports. Often, this evidence requires an expert to explain it – to be able to communicate the findings and data to the members of the court to make an informed decision. These experts are typically in medicine, engineering, psychology, or other fields.
Expert astronomers usually are not what one pictures in court, but that is exactly what I do.
The first time I was asked by police to do it came as a bit of a surprise. I had never thought about applying astronomy to the courtroom. Once the first group knew I can do it, more and more requests came in, from colleagues in the same police force or division, or investigators having seen my evidence elsewhere.
Now, I’m asked to submit evidence for roughly 1–2 cases per week. Usually this requires submitting a statement of evidence to the court. But sometimes I am asked to attend court and explain what the evidence means.
When I’m needed as an expert in court, it tends to be for matters of consequence. My evidence is either critical to a part of the case, or the case itself is fairly major and all the details are being checked and verified.
But what exactly am I providing evidence for?
Tracking the Sun and the Moon
Most court evidence from an astronomer involves calculating the positions and lighting from an astronomical body – the Sun or Moon. Luckily, the tools we use to calculate the positions of celestial bodies are very accurate, and can be calculated hundreds to thousands of years into the past or future.
An obvious example is when someone claims the Sun was in their eyes, causing a glare, and they get into a car accident. Someone needs to say where the Sun was, its position, and how it aligned with the street and direction of travel. At certain times and in certain directions, the Sun may indeed hinder someone’s vision.
There is also the situation where someone sees something, but it happened around sunrise or sunset. An expert is needed to say what the lighting level was – as there are very clear definitions based on the Sun’s position below the horizon, and how much you can see. For instance, what if the event occurred five minutes after sunset? The light level depends on the time of year, the location and other factors. It is not a clear-cut case of daytime versus nighttime.
The Moon can feature in court evidence as well. Especially in dark locations away from city lights, an astronomer can provide evidence on how much light the Moon provided on a given night.
There are also historical cases or times when people note the view or phase of the Moon as a way of defining when something happened. The full Moon has a precise definition, but the day before or after may appear to look like a full Moon, despite it not technically being full.
Gibbous, full, waning? Astronomers can define the phases of the Moon with greater precision, which can be useful in a court case. Patrick Ilao/Unsplash
The limitations of expertise
Of course, like any part of science, there are limits to what I can say. If someone was looking through a window – how refractive was the window? Were there clouds blocking the Moon or Sun? It is up to other experts, and other parts of the legal system to sort out these factors.
Just like many fields, space technology is changing, and so too is its impact on law and crime. Satellites are being used more and more in cases to help track things as they happen. For example, the space technology company Maxar operates some of the highest-resolution commercial satellites to image Earth. For a small cost, people can task these satellites to look at certain areas and/or times.
Lately, we have seen the impact of satellites on Russia’s war in Ukraine, and how they have been instrumental in looking at troop movements, and even evidence of some of the alleged war crimes.
They are also being used in Australia for criminal matters. This is yet another situation where an expert is needed to explain the satellite imagery and what it may mean, or even help access it altogether.
Experts are vital
Working as an expert witness has given me hope, because I see the extent to which the justice system will sometimes go to get all the details right – like taking into account the phase of the Moon or the position of the Sun. It is also the perfect example of the importance of experts in our society.
In science, we are actively encouraging people to go to sources of accurate and trustworthy information, especially in an era of rife misinformation.
Through experts, fields like space and astronomy can impact people’s lives directly – even in the court room.
“He made a party to celebrate his son’s birthday.”
These phrases might sound off to the ears of most English-speaking Americans.
In Miami, however, they’ve become part of the local parlance.
According to my recently published research, these expressions – along with a host of others – form part of a new dialect taking shape in South Florida.
This language variety came about through sustained contact between Spanish and English speakers, particularly when speakers translated directly from Spanish.
When French collided with English
Whether you’re an English speaker living in Miami or elsewhere, chances are you don’t know where the words you know and use come from.
You’re probably aware that a limited number of words – usually foods, such as “sriracha” or “croissant” – are borrowed from other languages. But borrowed words are far more pervasive than you might think.
They’re all over English vocabulary: “pajamas” from Hindi; “gazelle” from Arabic, via French; and “tsunami” from Japanese.
Borrowed words usually come from the minds and mouths of bilingual speakers who end up moving between different cultures and places. This can happen when certain events – war, colonialism, political exile, immigration and climate change – put speakers of different language groups into contact with one another.
When the contact takes place over an extended period of time – decades, generations or longer – the structures of the languages in question may begin to influence one another, and the speakers can begin to share each other’s vocabulary.
One bilingual confluence famously changed the trajectory of the English language. In 1066, the Norman French, led by William the Conqueror, invaded England in an event now known as “the Norman Conquest.”
Soon thereafter, a French-speaking ruling class replaced the English-speaking aristocracy, and for roughly 200 years, the elites of England – including the kings – did their business in French.
An 18th-century illustration of the Battle of Hastings, which initiated the Norman Conquest of England in 1066.
English never really caught on with the aristocracy, but since servants and the middle classes needed to communicate with aristocrats – and with people of different classes intermarrying – French words trickled down the class hierarchy and into the language.
During this period, more than 10,000 loanwords from French entered the English language, mostly in domains where the aristocracy held sway: the arts, military, medicine, law and religion. Words that today seem basic, even fundamental, to English vocabulary were, just 800 years ago, borrowed from French: prince, government, administer, liberty, court, prayer, judge, justice, literature, music, poetry, to name just a few.
Spanish meets English in Miami
Fast forward to today, where a similar form of language contact involving Spanish and English has been going on in Miami since the end of the Cuban Revolution in 1959.
In the years following the revolution, hundreds of thousands of Cubans left the island nation for South Florida, setting the stage for what would become one of the most important linguistic convergences in all of the Americas.
Today, the vast majority of the population is bilingual. In 2010, more than 65% of the population of Miami-Dade County identified as Hispanic or Latina/o, and in the large municipalities of Doral and Hialeah, the figure is 80% and 95%, respectively.
Of course, identifying as Latina/o is not synonymous with speaking Spanish, and language loss has occurred among second- and third-generation Cuban Americans. But the point is that there is a lot of Spanish – and a lot of English – being spoken in Miami.
Cuban refugees on the island of Cay Sal wait for the U.S. Coast Guard to take them to Florida in 1962.
Among this mix are bilinguals. Some are more proficient in Spanish, and others are more skilled English speakers. Together, they navigate the sociolinguistic landscape of South Florida in complex ways, knowing when and with whom to use which language – and when it’s OK to mix them.
When the first large group of Cubans came to Miami in the wake of the revolution, they did precisely this, in two ways.
First, people alternated between Spanish and English, sometimes within the same sentence or clause. This set the stage for the enduring presence of Spanish vocabulary in South Florida, as well as the emergence of what some people refer to as “Spanglish.”
Second, as people learned English, they tended to translate directly from Spanish. These translations are a type of borrowing that linguists call “calques.”
Calques are all over the English language.
Take “dandelion.” This flower grows in central Europe, and when the Germans realized they didn’t have a word for it, they looked to botany books written in Latin, where it was called dens lionis, or “lion’s tooth.” The Germans borrowed that concept and named the flower “Löwenzahn” – a literal translation of “lion’s tooth.” The French didn’t have a word for the flower, so they too borrowed the concept of “lion’s tooth,” calquing it as “dent de lion.” The English, also not having a word for this flower, heard the French term without understanding it, and borrowed it, adapting “dent de lion” into English, calling it “dandelion.”
A new lingo emerges
This is exactly the sort of thing that’s been happening in Miami.
As a part of my ongoing research with students and colleagues on the way English is spoken in Miami, I conducted a study with linguist Kristen D’Allessandro Merii to document Spanish-origin calques in the English spoken in South Florida.
For example, we found people to use expressions such as “get down from the car” instead of “get out of the car.” This is based on the Spanish phrase “bajar del carro,” which translates, for speakers outside of Miami, as “get out of the car.” But “bajar” means “to get down,” so it makes sense that many Miamians think of “exiting” a car in terms of “getting down” and not “getting out.”
Locals often say “married with,” as in “Alex got married with José,” based on the Spanish “casarse con” – literally translated as “married with.” They’ll also say “make a party,” a literal translation of the Spanish “hacer una fiesta.”
We also found “semantic calques,” or loan translations of meaning. In Spanish, “carne,” which translates as “meat,” can refer to both all meat, or to beef, a specific kind of meat. We discovered local speakers saying “meat” to refer specifically to “beef” – as in, “I’ll have one meat empanada and two chicken empanadas.”
And then there were “phonetic calques,” or the translation of certain sounds.
“Thanks God,” a type of loan translation from “gracias a Dios,” is common in Miami. In this case, speakers analogize the “s” sound at the end of “gracias” and apply it to the English form.
Examples of unique expressions that have emerged in Miami.
The Miami-born adopt the calques
We found that some expressions were used only among the immigrant generation – for example, “throw a photo,” from “tirar una foto,” as a variation of “take a photo.”
But other expressions were used among the Miami-born, a group who may be bilingual but speak English as their primary language.
In an experiment, we asked Miamians and people from elsewhere in the U.S. to rate local expressions such as “married with” alongside the nonlocal versions, like “married to.” Both groups deemed the nonlocal versions acceptable. But Miamians rated most of the local expressions significantly more favorably than folks from elsewhere.
“Language is always changing” is practically a truism; most people know that Old English is radically different from Modern English, or that English in London sounds different from English in New Delhi, New York City, Sydney and Cape Town, South Africa.
But rarely do we pause to think about how these changes take place, or to ponder where dialects and words come from.
“Get down from the car,” just like “dandelion,” is a reminder that every word and every expression have a history.
KENNEDY SPACE CENTER, Fla. — Sally Ride was the first American woman in space when she rode on Space Shuttle Challenger from KSC’s Launch Complex 39-A on June 18, 1983. She broke barriers, but she wasn’t alone. She was among six women named in 1978 as part of NASA Astronaut Group 8, all mission specialists. Ride was the first, but all six women from that class made it to space including Anna Fisher, who became the first mom in space when she launched on her lone mission aboard Space Shuttle Discovery in 1984. “I was assigned to my flight two weeks before my daughter was born,” Fisher said duri...
Incorporating the psychedelic drug psilocybin into psychotherapy shows promise in the treatment of depression, according to new research published in the Journal of Psychopharmacology. But the study also highlights the difficulty of implementing effective blinding procedures to prevent expectancy effects when researching psychedelic substances. Despite using a rigorous methodology, researchers found that nearly all participants were able to distinguish between a placebo and the active substance. Psilocybin is a naturally occurring alkaloid found in certain species of “magic” mushrooms. It is c...
Massive die-offs of birds on the coast of Mexico, following similar phenomena in Peru and Chile, are "most probably" due to a warming of the waters of the Pacific Ocean, authorities said Friday.
Mexico's agriculture and environment ministries "excluded the presence" of the AH5N1 virus responsible for bird flu and determined that the birds had starved to death.
"The most probable cause of this epidemiological event is the warming of the waters of the Pacific Ocean, due to the effects of the El Nino climate phenomenon," they said in a joint statement.
According to the ministries, the warming of the surface of the Pacific is causing fish to dive deeper, preventing birds from hunting them.
The El Nino weather phenomenon, generally associated with a rise in global temperatures, occurs on average every two to seven years and its effects are already being felt, the US National Oceanic and Atmospheric Administration (NOAA) announced last week.
In Mexico, the die-offs have mainly been among Buller's Shearwater, a vulnerable species, which live offshore and breed on islands, as well as among seagulls and pelicans.
These wild birds usually die offshore and are washed ashore by ocean currents, according to the same statement, which said research is ongoing.
The European sturgeon is one of the fish species declared to have disappeared entirely from Swiss waters © JEAN-PIERRE MULLER / AFP
The European sturgeon is one of the fish species declared to have disappeared entirely from Swiss waters © JEAN-PIERRE MULLER / AFP
