A 2025 study by South Korean researchers caught the attention of the astronomy community when it suggested that the evidence behind dark energy could be wrong. Dark energy makes up about 70% of the universe but nobody knows what it is. This makes it a frequent target for scepticism.

Scientists had long known that the universe was expanding. But in the late 1990s, researchers discovered that this expansion was accelerating. Astrophysicists concluded that something must be driving the acceleration. They named this unknown quantity “dark energy”.

The 2025 re-analysis, by a team at Yonsei University in Seoul, suggested that the expansion of the universe was not in fact accelerating.

Our team at the University of Southampton has now gone through the Yonsei team’s findings. Our results, published in Monthly Notices of the Royal Astronomical Society (MNRAS), suggest that the results were a false alarm.

However, the Yonsei University team have said they stand by their results and that a follow up study supports their finding that the universe may not be accelerating.

What is dark energy?

In the late 1990s, cosmology was upended by a startling discovery. Scientists knew the universe was expanding, but they had assumed that gravity was gradually slowing down this expansion.

However, by observing incredibly bright, thermonuclear explosions of white dwarf stars, two independent teams of astronomers found the opposite. Because these explosions, known as Type Ia supernovae, have almost the same intrinsic brightness, comparing how bright they appear gives a precise distance.

In 1998, data revealed that distant supernovae were fainter than they should have been in a slowing universe. Because faintness implies distance, the observations placed these supernovae farther away than expected, and implied that the cosmic expansion was not slowing.

In fact, when the calculations were run, it was clear that the expansion of the universe was actually speeding up.

There was no convincing physical explanation for this “cosmic acceleration”. Physicists labelled the mysterious, repulsive force that causes the acceleration “dark energy”.

Cosmic calibration

To understand the Yonsei University group’s claims, we must understand how astronomers use supernovae as “standard candles” to measure cosmic distances. Type Ia supernovae are remarkably alike, but they are not identical.

Cosmologists correct for these differences. They use subtle calibrations to account for relationships between the brightness of the supernovae and measurements like their colour, the duration of their light curves, and the type of galaxies they explode in.

One of those corrections is well known but subtle. It links the brightness of a supernova to the size of the galaxy it exploded in. Big galaxies hold more stars, and so more mass. After the standard corrections, supernovae in those big (massive) galaxies come out a few per cent brighter than ones in small galaxies. Nobody knows why.

But bigger galaxies typically have older stars that are made up of heavier elements, which could in turn influence the properties of the supernovae that some of those stars become. The authors of the 2025 study proposed a far bigger evolutionary effect. They argued that the brightness of Type Ia supernovae changes significantly as the universe ages.

Specifically, they claimed that older white dwarf stars, which are more common in the nearby, present-day universe, produce brighter explosions. That would mean today’s supernovae are inherently much brighter than their distant, early-universe counterparts.

If true, the faintness we observe in distant supernovae would not be a result of their being further away, a relationship that is in turn driven by dark energy, but rather an evolutionary trait of the stars themselves. This claim threatened to dismantle almost three decades of progress in astronomy.

Addressing the claims

Extraordinary claims need careful testing. At the University of Southampton we embarked on an audit of the data, using observations from the Dark Energy Survey (DES), an astronomy project designed to constrain dark energy’s properties, alongside the same dataset used by the authors of the 2025 work. In doing so, we sought to replicate and test their conclusions.

Our re-analysis revealed what we saw as two problems in the Yonsei study: a technical omission and a flawed assumption about stellar populations. Once corrected, the data fell back in line with standard cosmological results, including those of DES.

Crucially, the 2025 study did not account for how supernovae in big galaxies come out a few per cent brighter than ones in small galaxies. When our team reapplied this correction to the same dataset, the correlation between a supernova’s brightness and galaxy age – presented by the Yonsei team in their paper – became far weaker.

This doesn’t mean that the age of a white dwarf star has no effect on the brightness of a resulting supernova. Indeed, most researchers in the field would likely accept that the brightnesses of supernovae are more affected by the age of the stars that explode than by the mass of the galaxy that it is in.

However, measuring a galaxy’s mass is far less expensive in terms of telescope time and requires fewer technical assumptions than measurements of the ages of galaxies, which are challenging. What we showed is that the galaxy mass calibration is adequate to the accuracy required to constrain dark energy.

Secondly, the 2025 analysis relied on a flawed proxy, incorrectly assuming that the overall age of a host galaxy is identical to the specific age of the star that exploded. But galaxies are not uniform like this: even large, ancient galaxies contain localised pockets of young stars.

By overestimating the difference in age between the stars that explode nearby and those that explode in the distant universe, by a factor of three to five, the Yonsei University study overestimated the amount by which the age-brightness calibration could bias supernova distance measurements.

Once these omissions were corrected, the data behaved as expected under the standard model of cosmology. As such, evidence for an accelerating universe remains secure.

Science friction

While the 2025 study turned out to be incorrect, the challenge it posed was valuable. Challenging accepted ideas and rigorously testing our observations is fundamental to scientific progress.

Their claims provided an opportunity for cosmology teams to return to their baseline data, interrogate their core assumptions, and test different ways of calibrating the measurements. When measuring distances, however, the age effect and the mass effect are highly correlated, and therefore we (the Southampton team) believe it is incorrect to make a full age-based adjustment to distances that have already been corrected for the mass effect.

The Southampton team was invited, among others, to a workshop at Yonsei in June 2026, where we discussed our methods and talked about ways to include both stellar mass and stellar ages into the brightness corrections.

In a follow up study, recently accepted by MNRAS, the Yonsei University team maintain that the ages of stars have an important effect on the supernovae they produce. They say that two methods used in earlier studies have suppressed the importance of this phenomenon.

When these effects are accounted for consistently, they explain, it leads to results similar to those in the 2025 study. “We therefore continue to find evidence that stellar-population age is an important factor in Type Ia supernova standardisation,” authors Junhyuk Son and Hyejeon Cho, told The Conversation.

“Because the typical ages of supernova host populations change with cosmic time, understanding this effect is important for precision measurements of the Universe’s expansion history.”

Future measurements will depend on understanding supernova explosions better. It is a job we hope the community can take on together. But none of this removes the need for dark energy: it is still there, and still unexplained.

Ultimately, we have shown that existing measurements of dark energy are robust. Rather than debating whether cosmic acceleration exists, the astrophysical community can return to the exciting task of figuring out what dark energy actually is and how we best measure it.

Over the next 10 years, the Vera C. Rubin Observatory in Chile will carry out a project known as the Legacy Survey of Space and Time, which will produce a sample of supernovae 20 times larger than the DES sample used in our analysis. There is no better time to be investigating the mysteries of dark energy.

Dr Phil Wiseman receives funding from the Science and Technology Facilities Council.

Mark Sullivan receives funding from the Science and Technology Facilities Council.

When you think of advanced futuristic clothing, what comes to mind?

Perhaps shirts that can detect and alert users to low blood glucose levels or socks that can track your running form, step count and speed? What about pyjamas that observe subtle bodily changes while you sleep leading to early detection of cancer or warn carers of imminent seizures? Imagine if all these were items that required no external power source, just the energy generated by your own body.

Although these products are not in the shops yet that day is not far off.

Researchers are already designing advanced textiles that look exactly like regular clothes or fabrics but come with with embedded electronic functions. These are referred to as electronics textiles, e-textiles or smart fabrics.

E-textiles integrate sensing, computation and power into fabrics so that the threads themselves become the sensors and the stitches become the circuits. These textiles can monitor health, temperature, motion and air quality. They can communicate wirelessly and harvest various forms of energy.

University and industry prototypes are currently progressing through clinical trials and are being tested outside labs. The global market for e-textiles is projected to reach over US$15 billion (£11.14 billion) by 2028.

Developments in e-textiles will revolutionise the way humanity views clothing; but at what cost?

A new type of waste

Electronic waste is the fastest growing EU waste stream with a record 62 million tonnes discarded in 2022.

Another 92 million tonnes of waste is generated globally from textiles; a figure expected to reach 134 million by 2030. Textiles alone account for 6.7% of global greenhouse gas emissions with the average European discarding a staggering 11kg of textiles per year.

Electronic textiles will bring a new kind of hybrid waste. E‑textiles commonly use mixed polymers, metal nanoparticle inks, and include components that create fire hazards within conventional textile recycling.

They can release toxic residues if incinerated or landfilled. This results in hazardous and precious materials becoming trapped within garments, leading not only to environmental and health problems, but to a loss of vital resources such as graphene and rare-earth elements. Silver, for instance, is used in conductive yarns, antimicrobial coatings, sensors and electrodes. We need to work out how to recover it because it is valuable as well as toxic to aquatic life in some forms.

So, it’s currently very difficult to recover the valuable materials used in smart clothing, after the shirt or socks are discarded.

At the current rate of e-textile growth, current disposal methods will need to change to cope with these new materials; particularly in the areas of reusability and recyclability.

The EU’s sustainable and circular textiles strategy is part of the EU’s plan to become the first climate-neutral continent. Regulators are now demanding clearer rules on recyclability, chemical safety and product lifespans, and starting to ask how e‑textiles will meet these requirements.

Industry practice is catching up more widely, and placing more responsibility on clothing producers. Digital product passports (these carry information about the materials and their environmental impact) and new recycling technologies are scaling up. These shifts mean manufacturers could face legal and commercial risk if they don’t consider the long-term impact of these products.

Preventing more waste

The good news is that sustainable e‑textiles are an engineering problem with practical solutions. Key measures that industry and funders could adopt now include:

1. design for disassembly. Removable electronic parts help separate electronics from textiles for recycling

2. material passports and transparency. Digital records of various components (such as polymers, inks and batteries) that enable safe sorting and recovery

3. biodegradable and recyclable conductors. Prioritising conductors free from precious metals and using alternatives such as screen printable carbon paste and recyclable conductive inks and yarns

4. energy-first design. Integrating textile energy harvesting (for instance, solar, thermoelectric, piezo/triboelectric nanogenerators) to reduce or eliminate batteries. Some garments embed antennas and wireless power receivers to avoid bulky batteries

5. standards for washability, durability and end-of-life testing. To ensure products survive real-world use and can be repaired rather than discarded.

None of these are optional extras: they determine whether e‑textiles become a public good or a new environmental liability. University research groups and industry consortia are starting to demonstrate printable, stretchable components and trial wireless power that reduce battery dependence, for instance. Printable, stretchable components are flexible electronic parts printed onto fabric that keep working as the textile bends and stretches. They make smart clothing comfortable, lightweight, washable and able to move naturally with the body.

Unless policymakers and industry players adopt sustainable design now, e-textiles could add a dangerous new layer to our global electronic waste mountain.

Governments need to set clear rules on recyclability and chemical safety for e‑textiles. University researchers must find methods to make e-textiles functional, affordable, sustainable and safe. Brands must publish material details and repair guides and ensure sustainable practices are being adhered to throughout their supply chain.

Investors should not fund throwaway novelty. Standards bodies must define test methods for washing, wear and end‑of‑life recovery.

These steps will steer the market toward durable, repairable and recyclable products that could change lives for the better.

Ian Williams receives funding from UK Research Councils, including the Engineering and Physical Sciences Research Council (EPSRC) and its Impact Acceleration Account.

Christina Webb receives funding from UK Research Councils, including the Engineering and Physical Sciences Research Council (EPSRC).

Stephen Beeby receives funding from UK Research Councils, including the Engineering and Physical Sciences Research Council (EPSRC).

Antarctica’s first ice sheet may have begun with a geological head start hidden deep beneath the continent. Millions of years before thick ice spread across the Northern Hemisphere, forces inside Earth lifted East Antarctica into a vast region of mountains and plateaus. The higher terrain became cold enough to preserve snow even when the planet [...]

East Antarctica hosts the largest ice sheet on Earth, containing enough water to raise global sea levels by 52 metres, were it to fully melt. Yet it has puzzled scientists for decades how and why this ice sheet formed.

In fact, there are two interlinked mysteries. First, Antarctica became covered in ice around 34 million years ago – a period known as the Eocene-Oligocene transition – while the Arctic region stayed largely ice-free for another 25 million years or so.

Carbon dioxide levels in the atmosphere were falling dramatically at the time, and played an important role in falling temperatures. But if that was the sole factor behind the transition, both poles should have cooled together. They didn’t.

This means that something else was probably giving Antarctica a head start.

The second mystery is that sea-surface temperatures in the Southern Ocean remained unexpectedly warm for 10 million years or so after the East Antarctic Ice Sheet formed. This is not what we’d expect to see if the ice sheet had formed purely in response to global cooling, in which case the surrounding oceans should have cooled considerably too.

My new study with colleagues based in the UK and Germany, published in Science, points to an answer buried deep below the ice sheets: Antarctica’s mountains, and the slow motion geological forces that built them.

A continent on the move

This story begins around 170 million years ago, when Antarctica and Africa were last joined together as part of the supercontinent Gondwana. Their split sent Antarctica on a trajectory toward the South Pole – and this massive rupture also set off a chain of events far below the surface.

When continents break apart, hot material from Earth’s mantle wells up beneath them, cools and then sinks. This swirling motion destabilises the base of the neighbouring continent, triggering a series of lava lamp-like instabilities that remove chunks of its deep roots, one by one.

These disturbances, called “mantle waves”, sweep below continents over millions of years, travelling more than 1,000 kilometres as they ripple through the hot, sticky rock beneath the landmass.

My research team discovered this phenomenon several years ago. In two Nature papers, we pieced together multiple independent lines of evidence that all pointed to the same conclusion: mantle waves can trigger diamond-bearing volcanic eruptions – violent explosions that rocket magma from the deep roots of the continents, more than 150 kilometres below the surface.

We also found these mantle waves can generate unexplained pulses of uplifting land far from the rift zones where the continent originally broke.

Using computer models that simulate how landscapes evolve over tens of millions of years, we have now traced the effect these waves could have had in East Antarctica. Near the coast, the rifting formed a towering cliff-like feature, called an escarpment, more than two kilometres high.

Hundreds of kilometres inland, the mantle wave stripped away rock deep beneath the continent. Like a hot air balloon rising after dropping its ballast, the land above slowly lifted, creating a vast plateau and triggering a wave of erosion across the landscape.

The uplift didn’t stop there. It kept migrating inland, taking roughly 100 million years to reach the Gamburtsev mountains, over 1,500km from the coast. This range is now buried under 3km or more of ice.

Elevation matters enormously for ice. Air temperature drops by roughly 1°C for every 100 metres of elevation gained, so even a modest additional uplift can tip a mountain range from losing its snow each summer to keeping it year round.

Until around 50 million years ago, most of the Gamburtsev mountains sat below 1.5km, too low for much snow to survive the summer. But our models show that from around this time, the wave of uplift (see video above) reached this mountain region and pushed much of the range above 2km. At this elevation, snow and ice could persist and start building up.

According to our calculations, by around 45 million years ago, enough of East Antarctica’s landscape had crossed this threshold for mountain glaciers to take hold and begin spreading.

According to another strand of our analysis, the ice sheet started to form at precisely this time. By the point of continental glaciation, the global temperatures had fallen from a high of around 30°C 50 million years ago, to closer to 20°C.

Once glaciers formed on the highlands, two feedback loops took over. First, ice and snow reflect far more sunlight than bare rock, so as the ice sheet grew, it cooled the surrounding region further. Our modelling suggests this alone lowered global temperatures by around 1°C.

Second, as the air over Antarctica cooled, it held less water vapour, which is a powerful greenhouse gas. Drier air meant a weaker insulating blanket over the region, allowing temperatures to fall further still.

Together, these feedback loops let the ice sheet expand from its mountain strongholds down to the coast, eventually merging into the single ice sheet we see today.

Crucially, the global cooling of roughly 1°C was not enough to freeze the Arctic, as northern hemisphere landmasses didn’t have the elevation to cross this threshold. It would take another 25 million years or so, and much lower CO₂ levels and global temperatures, before major ice sheets could build up there too.

The temperature change that came from ice sheet formation was not enough to make temperatures plummet in polar oceans around Antarctica either, reconciling both mysteries surrounding the origin of its ice sheet.

Setting the stage for ice ages

Our work shows how geology sets the stage for ice ages. The height of the land determines whether a given climate is cold enough to grow ice.

This concept is important for other climate events in Earth’s past. If deep Earth processes can condition a landscape for ice long before the climate cools enough for ice sheets to form, they may too have contributed to earlier ice ages.

Understanding the growth of past ice sheets can also give us clues about the future. Our study shows that the conditions required for a continental ice sheet to form are extraordinarily specific, and took geological timescales to assemble.

When ice sheets melt, however, they disappear much faster than they formed. And once lost, they cannot simply grow back.

Thomas Gernon receives funding from the WoodNext Foundation, a fund of a donor-advised fund program. Gernon is a Visiting Professor at the GFZ Helmholtz Centre for Geosciences in Potsdam, Germany.

A major challenge to dark energy, the mysterious force believed to be driving the universe’s accelerating expansion, has been overturned by a new study. Astronomers say a new analysis has reinforced one of the most important discoveries in modern cosmology, finding that the universe is still expanding at an accelerating rate. The result counters a [...]