Category: English

Source: The Conversation – UK – By Leanne McCarthy-Cotter, Programme Director for Politics and International Relations, Cardiff Metropolitan University

Nepal’s prime minister, KP Sharma Oli, resigned on September 9 as his country reeled from some of its worst unrest in decades. A government ban on 26 social media apps, including Facebook, WhatsApp, YouTube and X, triggered widespread protests. The police responded violently, 19 people were killed and hundreds more injured.

Demonstrations have escalated since then in the capital, Kathmandu, and some other cities. The homes of various politicians have been vandalised, the parliament building in Kathmandu was set on fire and the death toll has risen to 22.

Nepal’s army has announced it will take control of the situation. It has imposed a countrywide curfew and is warning of punishment for anyone involved in violence or vandalism. The gen Z groups leading the protests say the movement has been hijacked by “opportunist” infiltrators.

The forces that led to Oli’s exit run far deeper than anger at the government’s social media ban. This was merely the final straw. Anger at political instability, elite corruption and economic stagnation have built up over many years.

Nepal’s democratic era began in 2008 after a decade-long Maoist insurgency culminated in the abolition of its monarchy. Several years later, in 2015, a constitution came into effect that introduced federalism and proportional representation to address ethnic tensions and prevent authoritarian rule.

But it has instead produced a highly fragmented party system. None of the 14 governments that have ruled since 2008 have completed a full term. This revolving-door politics, underpinned by patronage-driven coalitions, has fuelled public cynicism.

Nepal also consistently ranks poorly on corruption indices. It was ranked 107 out of 180 countries in Transparency International’s 2024 Corruption Perceptions Index. Two major scandals have become symbols of elite impunity in Nepal.

The first concerns the Giri Bandhu Tea Estate. The estate’s owners – allegedly in collusion with politicians – have for decades attempted to convert land protected under law into commercial real estate for profit. Nepal’s supreme court struck down the latest attempt in February 2025.

The second is known as the Lalita Niwas land grab scam. Beginning in the 1990s, it involved the illegal transfer of government-owned land to influential businessmen, politicians and government officials. Several senior Nepalese officials have been arrested and subsequently convicted over their involvement.

Most recently, the so-called “Nepo kid” campaign has seen the luxury lifestyles of politicians’ family members showcased on social media. Among the most frequently shared images was a photo claiming to show a son of a minister posing with boxes labelled Louis Vuitton and Cartier, arranged into a Christmas tree.

The images have only crystallised public anger. Wealth inequality remains stark in Nepal, where the top 10% of earners receive three times more income than the bottom 40% of earners combined. And younger Nepalis feel excluded from opportunity.

With limited career prospects at home, many young people in Nepal see emigration as the only option. Roughly 839,000 Nepalis had to leave the country in 2024 to work abroad. For young Nepalis, these realities have bred deep disillusionment. Their demands are clear: they want systemic reforms that challenge the political elite.

What happens next?

What happens next is unclear. The Nepalese army played a decisive role in Oli’s resignation. Reports indicate that the army chief, General Ashok Raj Sigdel, privately urged Oli to step down and ensured a safe exit for him and key ministers.

Troops have also been deployed to protect government buildings and maintain order. But, while the army has committed to taking control of the situation, it has at no point attempted to seize power or suspend constitutional processes.

Unlike the overtly interventionist militaries of some states in the region, such as Pakistan, Nepal’s army has traditionally avoided direct involvement in government. It has instead acted as a stabiliser during political crises and has occasionally influenced leadership transitions behind the scenes.

In this sense, its facilitation of Oli’s exit was not entirely unprecedented. But what was striking was the public visibility and speed of the army’s intervention. Its leadership effectively communicated that the prime minister’s political survival depended on their acquiescence, while carefully framing itself as a neutral arbiter rather than a ruler.

Nepal will now enter a period of caretaker government. The country’s fractured coalition politics means forming a stable administration may prove difficult. However, figures such as Kathmandu’s mayor, Balendra Shah, are gaining popularity as symbols of generational change.

Shah, 35, has garnered significant support from young Nepalese people, who view him as a break from the country’s traditional political elites. His background as a rapper and civil engineer, coupled with his anti-corruption stance, resonates with young voters seeking authenticity and reform.

His active engagement on social media, which has included expressing solidarity with protesters, has further solidified his position as a leader aligned with the aspirations of the younger generations. And his independent status, free from the influence of traditional political parties, has allowed him to present himself as an outsider capable of enacting genuine change.

Yet on its own, a turnover of leadership – while addressing a symbolic grievance – is unlikely to satisfy all of the protesters. The slow roll-out of federalism and a lack of effective decentralisation have alienated rural populations. This has fed widespread perceptions of a Kathmandu-centric elite.

Nepalese youth are demanding change. For the country’s politicians, addressing this moment will require not only new leadership, but a genuine commitment to reform and a political system credible to a generation no longer willing to accept business as usual.

Without this, Nepal risks remaining trapped in a cycle of protest and paralysis.

Leanne McCarthy-Cotter does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

– ref. Nepal’s social media ban sparks deadly protests, but deeper grievances fuel the fire – https://theconversation.com/nepals-social-media-ban-sparks-deadly-protests-but-deeper-grievances-fuel-the-fire-264923

Source: The Conversation – UK – By Michelle Spear, Professor of Anatomy, University of Bristol

In recent years, skulls, bones, and even modified human remains have appeared with increasing frequency on online marketplaces and social media platforms. What might once have been confined to specialist collectors has become a global, online trade.

The market is fuelled by diverse groups of buyers. Some are traditional collectors of curiosities, others are ritual practitioners. And a smaller number of contemporary artists and designers buy human remains to incorporate into sculptures or installations, raising concerns about the use of the body as raw material. There are also medical and dental students, some of whom still seek real skulls for their own study, unaware of the legal and ethical pitfalls.

Perhaps the most striking development is the rise of casual consumers inspired by social media. The aesthetic known as “dark academia” has helped to drive this surge. Blending gothic literature, candlelit libraries, vintage tailoring and scholarly mystique, it presents bones as fashionable props. On Instagram (#SkullDecor) and TikTok (#OdditiesTok), users pose with skeletons in the same way they might with antique books or candlelight, transforming skulls into lifestyle decor.

This trend is troubling because it normalises ownership of human remains and blurs the line between objects of study and human individuals. By aestheticising death, it risks eroding the ethical safeguards that once protected the dead from exploitation. The surge has prompted alarm among archaeologists, anthropologists and anatomists. The British Association for Biological Anthropology and Osteoarchaeology has spearheaded a campaign to curb the trade, warning that it not only exploits the dead but also risks commodifying them. Yet the legal framework is equally complex, leaving many sellers operating in a grey area.

In the UK, the law is fragmented. The Human Tissue Act 2004 regulates the use of bodies donated for anatomical education, teaching and research, but only applies to remains less than 100 years old. Anything older falls outside its scope.

This century cut-off creates a loophole: a skull described as “Victorian” can be sold, even if its provenance is doubtful. Sellers may exploit this grey area, and buyers rarely question such claims.

Sidestepping jurisdictions

Elsewhere, laws are inconsistent. In the US, Native American remains are protected under federal legislation, yet state laws vary widely and online sales often slip through the net. The global nature of the trade makes enforcement harder still: a skull listed in the UK can be shipped abroad with little difficulty, sidestepping different national jurisdictions.

The question of origin is central. The Anatomy Act of 1832 was intended to end grave robbing in Britain by providing a legal supply of bodies – those unclaimed in hospitals, prisons and workhouses – while also making body donation legal. But demand soon outstripped supply, as evidenced by the work of the resurrectionists, and by the late 19th-century Britain looked abroad for bones.

India became the world’s largest exporter, sending an estimated 60,000 skeletons overseas in 1984 alone. Many came from impoverished communities who could not afford cremation or burial, while others were stolen from cemeteries.

Grave robbing was common, and the trade remained deeply tied to colonial structures. Even after independence in 1947, India remained Britain’s main supplier until a scandal in 1985 revealed the export of 1,500 child skeletons, raising fears of kidnapping and murder. The Indian government swiftly banned the trade. China then became the leading exporter until it too banned exports in 2008.

This history shows that many of the bones circulating today in collections, and sometimes resurfacing on the open market, were acquired in ways that were profoundly exploitative.

Provenance is everything, yet often absent. While many bones circulating today are former anatomical specimens, the scale of demand has clearly encouraged more nefarious means of procurement, and grave robbing has seen a resurgence.

Museums and teaching collections usually keep detailed acquisition records, so bones offered without documentation raise immediate red flags. Anatomical specimens also tend to show signs of preparation, such as drilled holes, varnish or metal fittings.

By contrast, remains taken from graves often display soil staining, root etching, or microfractures caused by long-term burial. Fragments of coffin wood, nails or textiles may still cling to them. These differences are not always conclusive, but together they suggest whether a skeleton was prepared for study or exhumed illicitly.

Beyond legality lies a more fundamental question: should human remains ever be sold at all? Human remains are not ornaments or lifestyle accessories – they are the material traces of people’s lives.

The commodification of human remains sits at the uneasy intersection of law, science and ethics. The trade thrives because of loopholes and because platforms profit from traffic even when listings violate their own policies. At its heart, this is not a legal issue so much as one of respect.

Human remains, whether ancient or recent, represent lives once lived. They carry stories of identity, community and mortality. Treating them as commodities diminishes both the individuals they once were and the societies we live in today. As calls for reform continue, the challenge is to shift attitudes away from possession and decorative display toward recognition of the dignity owed to the dead.

Michelle Spear does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

– ref. Trading human remains: why bones should not become a commodity – https://theconversation.com/trading-human-remains-why-bones-should-not-become-a-commodity-264208

Source: The Conversation – UK – By Adam Taylor, Professor of Anatomy, Lancaster University

It might seem like a harmless habit to linger on the loo with your phone while “taking care of business”, but research shows that prolonged toilet time can increase the risk of several health problems. Here are the main ones.

1. Haemorrhoids

A recent study found that smartphone use while doing a number two is linked to a 46% increased risk of developing haemorrhoids. A healthy toilet trip should only last two to three minutes, yet the study found that 37% of participants who used their phones while on the can spent more than five minutes there.

Haemorrhoids are enlarged blood vessels occurring in or around the anal opening. They develop due to increased pressure in the anal cushions – a part of the spongy tissue that surrounds your anus. These cushions allow the anus to expand as faeces is expelled.

Sitting too long on the toilet places extra pressure on these cushions, leading to haemorrhoids, as does straining to force faeces out.

It’s estimated that between 50-85% of people worldwide suffer from haemorrhoids. Symptoms include painless bleeding, irritation, itching and discomfort. However, haemorrhoids aren’t always symptomatic. Some people have them without knowing.

Haemorrhoids can also lead to complications such as anaemia from prolonged bleeding, and strangulation or clotting within the haemorrhoid – both of which cause severe pain.

2. Anal fissures or tears

Sitting on the toilet too long can cause anal fissures or tears. They are small cuts in the anal lining. Anal fissures are often accompanied by significant pain – likened to passing broken glass when having a bowel movement, alongside bright red blood.

The anal lining is thin and sitting on the toilet for too long causes pooling of the blood, which stretches the lining, making it more prone to damage as faeces passes out.

3. Prolapse

Faeces may not be the only thing that passes out the body after sitting on the toilet. Extended loo time can increase your risk of having your rectum fall out of your body – a condition known as a rectal prolapse.

This uncommon condition occurred in one man who would often spend up to 30 minutes on the toilet playing smartphone games. One day, he found nearly 14cm of his rectum protruding out of his body while attempting a bowel movement.

Prolonged sitting on the toilet increases pressure in the abdomen, which subsequently increases pressure on the pelvic floor muscles. These muscles help hold our internal organs, including our rectum, inside. But prolonged pressure can weaken these muscles.

In women, this could also result in other pelvic organs – such as a uterus – prolapsing out of the body.

Rectal prolapse is often painful, and you’ll need to visit the hospital if you have one so it can be re-inserted. If it happens repeatedly or if the case is particularly extreme, it will require surgery.

4. Pressure sores and ulcers

Prolonged sitting on the loo, particularly in the elderly, may increase the risk of pressure sores occurring on the skin that comes in contact with the toilet seat.

Prolonged sitting compresses the tissues, reducing blood flow to them. This then results in toxic substances building up in the blood which damage the tissues and cause them to breakdown. Pressure sores are painful.

5. Hiatal hernia

Prolonged sitting on the toilet and straining to defecate may contribute to hiatal hernia, particularly in susceptible people (including those who are obese or over the age of 50).

This is where part of the stomach and other abdominal organs slide through the opening in your diaphragm (a dome-shaped muscle that helps us breathe), ending up in the chest cavity.

Hiatal hernias are common, affecting 20% of people. They typically result in indigestion, stomach pains and discomfort around the ribs and chest. They can be treated with medication to reduce the amount of acid produced by the stomach or in more severe cases require surgery.

6. Toilet seat neuropathy

Sitting too long on the toilet compresses the major nerves and blood vessels, reducing blood supply to the legs. This can cause your legs to go numb as a result – a phenomenon known as toilet seat or toilet bowl neuropathy. It usually goes away after a few minutes.

But there have been some case studies where patients who passed out on the toilet after a night of drinking – subsequently spending the night there – found themselves entirely numb and unable to move. In one extreme case, a man developed gangrene, sepsis and sadly died after falling asleep on the toilet.

7. Fainting

Prolonged toilet time combined with straining may also result in fainting.

This condition, called vasovagal syncope, occurs when prolonged straining on the toilet irritates the vagus nerves. These nerves control many of the body’s automatic functions – including heart rate and blood pressure.

In the case of defecation syncope, blood pressure can drop suddenly when we stand up from the toilet. Heart rate also drops causing dizziness, light-headedness and fainting.

The healthy way to poo

To reduce your risk of suffering any of these conditions, spend as short a time seated on the loo as possible.

You could also potentially modify your position when using the loo. Some evidence suggests squatting is better for defecation, as it reduces the stress and straining needed to poo. However, other studies have shown this position could potentially increase risk of other health problems – such as risk of stroke and damage to the achilles tendon.

Other advice includes eating more fibre and drinking water if you’re someone who regularly takes longer than five minutes to do your business as both can help you have healthier poos. They will also prevent straining while having your bowel movement.

Adam Taylor does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

– ref. Seven health conditions that show why using your phone on the toilet is a bad idea – https://theconversation.com/seven-health-conditions-that-show-why-using-your-phone-on-the-toilet-is-a-bad-idea-264808

Source: The Conversation – UK – By Anne Irfan, Lecturer in Interdisciplinary Race, Gender and Postcolonial Studies, UCL

At the end of August, the Trump administration blocked Palestinian president, Mahmoud Abbas, and 80 other Palestinian officials from attending the UN general assembly meeting in New York, which runs between September 9 and 23. The US president’s decision to revoke the Palestinian officials’ US visas comes as various European governments prepare to formally recognise the state of Palestine at the general assembly. Supporters of Palestinian statehood are proposing a central role for Abbas’ Palestinian Authority (PA) in Gaza’s future government.

Historically, the US has also supported the PA. The Oslo accords, which created the PA in the first place, were signed at the White House in 1993. US president Bill Clinton famously hosted Israeli prime minister Yitzhak Rabin and the chair of the Palestine Liberation Organisation (PLO), Yasser Arafat.

In discourse that has since become standard US policy, Clinton spoke of a so-called “two-state solution”, with security for Israel and democratic self-rule for the Palestinians. The US provided significant financial support for the PA after its establishment, with particular funding for its ample security forces.

Yet behind the scenes, the US stance on Palestinian statehood has always been murkier. A deeper look shows that the Trump administration’s recent moves blocking the PA are less of a departure from long-term US policy than they may seem. As I explain in my new book A Short History of the Gaza Strip, the US has long paired its ostensible support for the PA with policies that cripple its ability to function and undermine prospects of real Palestinian independence.

From the start, the Oslo accords were skewed in favour of Israeli interests. Under the agreement’s terms, the PA had limited autonomy over around three-quarters of the Gaza Strip and less than one-fifth of the West Bank. The Israeli military retained ultimate control and continued to seize more land for illegal settlements.

At the end of the 1990s, Clinton aligned himself closely with the new Israeli prime minister, Ehud Barak. Barak’s declared “red lines” included no Palestinian state along the 1967 borders, no Palestinian national army, no Palestinian sovereignty over any part of Jerusalem and the retention of most illegal Israeli settlements in the West Bank.

Further negotiations were structured to constrain the Palestinians, culminating in the “failure” of the 2000 Camp David summit. Familiar to anyone who has followed Israeli-Palestinian affairs, Arafat has been blamed for refusing Barak’s “unprecedented” proposal. The reality is somewhat different.

As Robert Malley and Hussein Agha wrote in their 2001 book, Camp David: a tragedy of errors, “what so many viewed as a generous Israeli offer, the Palestinians viewed as neither generous, nor Israeli, nor, indeed, as an offer”. Malley served as adviser to Clinton on Arab-Israeli affairs while Agha, a senior associate member of Oxford University’s St Antony’s College has been associated with Israeli-Palestinian affairs for more than half a century – meaning they know whereof they speak.

The US’ disingenuous approach did not end when Clinton left office. During the second intifada (Palestinian uprising) from 2000-2005, the administration of George W. Bush backed Israel’s full invasion of PA-administered areas in the West Bank and Gaza. This completely undermined any chance of a two-state solution – the very “solution” that the US ostensibly supported.

In 2003, the US demanded a full restructuring of the PA’s set-up to curtail Arafat, whom Palestinians had elected president in 1996. When he died in 2004, he had spent two years under Israeli siege in Ramallah – another policy supported by the US.

Two years later, US moves to undermine the PA reached a crescendo when the 2006 Palestinian parliamentary elections returned Hamas as the largest party with 44% of the vote. While the elections were deemed free and fair by international observers, the Bush adminstration responded by plotting, arming and funding a coup to overthrow the new PA government.

In the end, the coup backfired, resulting in a lasting split from 2007 when Hamas seized control of Gaza and Abbas’ forces purged it from the PA in the West Bank. Since then, Palestinians in the two territories have been largely cut off from one another under two separate regimes. Abbas’ PA has been based in the West Bank while Hamas governs Gaza – where Israel has imposed a full blockade from 2007, supported by the US and Egypt.

No authority

In the two decades since, successive US administrations have effectively facilitated the Palestinian divide. In 2014, the Obama administration backed Israeli opposition to a short-lived Palestinian unity government. And when Abbas cancelled long-awaited Palestinian elections in 2021, the Biden administration stayed silent, with reports of tacit US support for the move behind the scenes.

While many western and Arab states are calling for the PA to take over Gaza’s future governance, critics point out that it has long been toothless and illegitimate.

Elected in 2005, Abbas is now 20 years into a four-year term. What’s more, his regime has delivered little for West Bank Palestinians in the nearly two decades since the split from Gaza.

He has been entirely ineffectual in countering the Israeli war on Gaza, launched after the Hamas-led attacks of October 7 2023 and widely recognised as genocide. As ministers call to resettle Gaza, Israel has continued to expand its illegal settlements in the West Bank and is openly planning ethnic cleansing.

It is important to remember that the PA was only ever created as an interim body, designed to serve for five years in the 1990s ahead of final negotiations. Its continued existence decades later is a serious indictment of the US-led so-called peace process. The reality of US treatment of the PA since the 1990s calls into question whether Trump’s recent moves are really a turning point in US policy – or simply the culmination of a long-term trend.

Anne Irfan does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

– ref. How America helped create the Palestinian Authority – only to undermine it ever since – https://theconversation.com/how-america-helped-create-the-palestinian-authority-only-to-undermine-it-ever-since-264759

Source: The Conversation – UK – By Sean McMahon, Reader in Astrobiology, University of Edinburgh

Just over a year ago, Nasa made a remarkable announcement. The Perseverance rover had found potential signs of ancient life on Mars. Now, the technical details behind that discovery have been published in a Nature paper that, despite its rather modest wording, may ultimately prove to be among the most significant in the history of science.

The bottom line is this: it might be life, but we won’t know for sure until we return the samples to Earth. Perseverance has already collected a fragment of the relevant rock — we just have to go and get it.

Indeed, Nasa has been working with the European Space Agency on a mission to go to Mars, retrieve the samples of rock collected by Perseverance and deliver them to Earth. This would include the sample from the rock that’s the subject of the Nature study. However, the mission, known as Mars Sample Return, has run into trouble because of rising costs.

In mid-2024, the Perseverance rover encountered a block of ancient mudstone, nicknamed Cheyava Falls, distinguished by its brick-red hue. This rock was laid down by water roughly four billion years ago. While most Martian rocks appear red due to a coating of oxidised (ferric) iron dust, Cheyava Falls is red through and through – the ferric iron is in the rock itself.

More intriguingly, Cheyava Falls is peppered with dozens of tiny pale spots, typically less than a millimetre across. These spots are fringed with a dark phosphorus-rich mineral, which also appears as tiny dots called poppy seeds that are scattered between the other spots. Associated with this mineral are traces of ancient organic compounds. (Organic compounds contain carbon and are fundamental to life on Earth, but they also exist in the absence of biology.)

What does this have to do with life?

All living organisms on Earth harness energy through oxidation-reduction (redox) reactions – transferring electron particles from chemicals known as reductants to compounds named oxidants. On Earth, for example, structures called mitochondria in animal cells transfer electrons from glucose (a reductant) to oxygen (an oxidant). Some rock dwelling bacteria use other kinds of organic compound instead of glucose, and ferric iron instead of oxygen.

When ferric iron is reduced to a different form, known as ferrous iron, it becomes soluble in water and either leaches away or reacts to form new, lighter-coloured minerals. The result is that many red rocks and sediments on Earth contain small bleached spots – “reduction spots” – strikingly similar to those found in Cheyava Falls. In fact, Perseverance subsequently spotted bleached features even more reminiscent of reduction spots at a site called Serpentine Rapids, but spent too little time there to analyse them and, unfortunately, didn’t collect any samples.

The new Nature paper builds on abstracts presented at the Lunar and Planetary Science Conference, held in Houston in March 2025, but with more detail and the added weight of peer review. It confirms that the pale spots are associated with organic matter, and that they contain ferrous iron and sulphur – specifically, an iron-sulphide mineral.

The most plausible interpretation is that redox reactions occurred within the rock after it formed, transferring electrons from organic matter to ferric iron and sulphate, and producing bleached zones where ferric iron was depleted.

Notably, these reactions – especially sulphate reduction – don’t typically occur at the low temperatures this rock experienced over its history. Unless microbes are involved, that is. Microbial oxidation of organic matter can also produce phosphate minerals, like those found at Cheyava Falls.

Without getting samples back to laboratories on Earth, there’s only so much we can really know about what happened at Cheyava Falls four billion years ago. Even so, no entirely satisfying non-biological explanation accounts for the full suite of observations made by Perseverance.

The new paper does a good job of making this clear, considering the possibilities one by one. But in astrobiology, the lack of a non-biological explanation isn’t where life detection ends – it’s where it begins. History tells us that when we can’t think of a non-biological explanation for something, it’s usually not because there isn’t one. It’s just that we haven’t thought of it yet.

So what happens next? First, astrobiologists around the world must explore which oxidation-reduction reactions involving iron, sulphur, organic compounds, and phosphate can occur with and without biology under conditions relevant to Cheyava Falls.

Second, Nasa and other space agencies must provide bold leadership on the Mars Sample Return mission. Yes, it will be expensive – possibly tens of billions of dollars – but the payoff could be the most important scientific discovery ever made.

Sean McMahon has previously received funding from NASA.

– ref. Signs of ancient life may have been found in Martian rock – new study – https://theconversation.com/signs-of-ancient-life-may-have-been-found-in-martian-rock-new-study-264960

Source: The Conversation – UK – By Patricia Schmidt, Associate Professor of Physics, University of Birmingham

Black holes may be the fiercest objects in the universe, yet we still know very little about them. It has only been a decade since we confirmed their existence by detecting gravitational waves: ripples in the fabric of spacetime.

Since then, gravitational waves from colliding black holes have unveiled insights into their hidden physics and the theories that support them. On January 14, 2025, the loudest gravitational-wave signal ever detected, known as GW250114, was observed by the two Laser Interferometer Gravitational Wave Observatories (LIGO).

This remarkable event provided our international team of scientists with a golden opportunity to test two major predictions of Albert Einstein’s theory of general relativity with unprecedented precision: the nature of black holes and something called Hawking’s area law theorem.

The results, published in Physical Review Letters, mark a significant step forward in our understanding of gravity and black holes.

Black holes are a key prediction of general relativity, our leading theory for describing gravity. Astrophysical black holes form when a massive star reaches the end of its life and collapses under its own gravity, exceeding a certain mass called the Chandrasekhar limit (approximately 1.44 times the mass of the sun).

What remains is a region of spacetime completely disconnected from communication with the rest of the universe, bounded by a surface known as the event horizon – from which nothing can famously escape, not even light. But if black holes cannot send signals or light beyond this boundary, how can we be sure they exist and that they behave as predicted?

The power of gravitational waves

General relativity actually predicted the existence of gravitational waves in the first place. Any massive object that accelerates through spacetime will generate tiny distortions that propagate away at the speed of light. These waves encode a wealth of information about the source and the nature of gravity itself.

To produce gravitational waves strong enough to be detected, we need systems where massive objects undergo sustained and intense acceleration. One of the most powerful sources is a binary black hole, where two black holes orbit each other under the influence of gravity. As gravitational waves carry energy away from the system, the orbit will gradually shrink until the black holes eventually merge into a single, larger black hole.

Hence, by analysing gravitational waves from black hole binaries we can probe whether astrophysical black holes truly behave as predicted by general relativity.

Gravitational waves were first observed by the LIGO detectors on September 14, 2015, when they captured the collision of two black holes known as GW150914. Due to the rapid improvements in detector technology, we are now able to observe binary black hole mergers in ultra-high definition, enabling the single most stringent tests of general relativity and black hole physics to date.

Hawking’s theorem

Despite their mathematical complexity, black holes are surprisingly simple objects entirely characterised by their mass, rotation and (possibly) electromagnetic charge.

In 1972, Stephen Hawking published a seminal study showing that as two black holes merge, the surface area of the final event horizon must be larger than the sum of the surface areas of the two initial black holes. This is known as the area law.

One way to understand this is to realise that the surface area of the event horizon scales with the mass and spin of the black hole in very particular ways. If we double the mass of a black hole, its event horizon becomes four times larger. If we make the black hole spin faster, the event horizon will become more oblate (think of a rugby ball) and the surface area will decrease. For merging black holes, Hawking demonstrated that despite the loss of energy and angular momentum to gravitational waves, it will always result in a final black hole that has a larger event horizon.

GW250114 provided us with a golden opportunity to test Hawking’s predictions.
By analysing the gravitational-wave data with the best available models, our team has now validated the area law to high significance. This was possible through the detailed modelling of the “ringdown”, the final stage after the merger during which the remnant black hole emits gravitational waves in a characteristic pattern (known as quasi-normal modes).

This process is similar to striking a bell: the tones emitted depend on the material and shape of the bell, with the ringing of the bell encoding this information. By analysing the emitted sound, we can figure out the shape and material of the bell. For rotating black holes, we can do something similar using gravitational waves.

By analysing the emitted waves and all its harmonics, we can reconstruct the mass and spin of the black hole, and hence the surface area of the horizon.
With a signal this strong, we were able to carry out a comprehensive suite of tests probing different aspects of Einstein’s theory. In every case, the predictions of general relativity held firmly.

The observation of GW250114 offers the clearest validation yet of Einstein’s theory, validating some of its most profound predictions, including Hawking’s area law. This is still just the beginning, and the next decade promises to revolutionise our understanding of gravity and black holes even further.

Patricia Schmidt receives funding from UK Research and Innovation (UKRI) through grants ST/V005677/1 and ST/Y00423X/1, and The Royal Society through a Research Grant RGR1241327.

Geraint Pratten is supported by The Royal Society through a University Research Fellowship (URFR1221500 and RFERE221015), the UK Space Agency (grant ST/Y004922/1), and UKRI (grants ST/V005677/1 and ST/Y00423X/1).

– ref. Crashing black holes validate Stephen Hawking – new research – https://theconversation.com/crashing-black-holes-validate-stephen-hawking-new-research-264995