Known as ‘vacuum birefringence’, the phenomenon was predicted nearly 90 years ago by Werner Heisenberg, one of the pioneers of quantum mechanics. His work suggested that a perfect vacuum is not truly empty. Instead, it should contain ‘virtual particles’ that briefly appear and disappear.

Researchers, including Dr. Marcus Lower from Swinburne University of Technology, investigated this long-standing quantum mystery by studying a magnetar, a rare type of neutron star that possesses the strongest magnetic fields known in the universe.

Their observations may represent the first detection of vacuum birefringence occurring within a magnetar’s extraordinarily powerful magnetic field. If confirmed, the result could give scientists a new way to investigate the quantum universe. The findings were published recently in Nature.

How Extreme Magnetic Fields Can Change Light

According to the theory, an exceptionally strong magnetic field can affect the sea of virtual particles associated with the vacuum. Under these conditions, the particles are expected to influence how light travels, refracting it in a specific way and producing vacuum birefringence.

Magnetars provide a rare opportunity to search for this effect because their magnetic fields are powerful enough to make the predicted quantum behavior potentially observable.

Dr. Lower was part of an international research team that studied the magnetar 1E 1547.0-5408 (or 1E1547 for short) with NASA’s Imaging X-ray Polarimetry Explorer (IXPE). The observations were supported by the NICER X-ray telescope aboard the International Space Station and Murriyang, CSIRO’s Parkes radio telescope, which is owned and operated by Australia’s national science agency.

Radio observations collected by Dr. Lower using Murriyang, followed by analysis on Swinburne’s Ngarrgu Tindebeek supercomputer, helped the researchers investigate what could be the first direct detection of this previously theoretical quantum phenomenon.

Although vacuum birefringence was predicted in the 1930s, Dr. Lower said scientists have yet to obtain a definitive detection.

“Detecting vacuum birefringence requires a magnetic field that is over 100 million times stronger than any we’ve ever made on Earth. Thankfully, nature has provided us with magnetars, which are the perfect cosmic laboratories to go looking for this effect,” Dr. Lower said.

A Magnetar With Ideal Viewing Geometry

The researchers closely followed how the radio waves coming from the magnetar changed direction as the star rotated (their ‘polarization state’). From those measurements, they determined that the magnetic and rotational axes of 1E 1547 are almost aligned. The magnetar is also observed from a nearly pole-on perspective.

Together, those characteristics give scientists an unusually favorable view for searching for vacuum birefringence around 1E 1547.

The team then found two important clues pointing toward the quantum effect. X-rays generated by the magnetar and detected by IXPE showed extremely high levels of polarization. In addition, the direction of that polarization remained tied to the magnetic field of 1E1547 in the same way seen in the radio observations.

“Because of the magnetic field’s strength, Heisenberg’s virtual particles become aligned with the direction the field is pointing,” Dr. Lower said.

“By carefully tracking the direction the radio waves and X-rays oscillate as the magnetar rotates, the team found that the alignment of 1E1547’s magnetic and rotational poles were ideal for detecting vacuum birefringence.”

Closing In on a 90 Year Quantum Mystery

If the interpretation is confirmed, the result could help physicists test how established theories of quantum physics behave under some of the most extreme conditions found anywhere in the universe.

Dr. Lower said additional observations and more advanced computer simulations could help establish whether the signal truly comes from vacuum birefringence. Those improvements should make it easier for researchers to distinguish the predicted quantum signature from other physical processes taking place around magnetars.

“With these future data on hand and our updated simulations, we may finally be able to complete the quest started by Heisenberg nearly 90 years ago.”

The paper titled “Vacuum birefringence and the polarized X-ray emission of a radio magnetar” has been published in Nature.

Gravity was the natural place to start. On average, the universe is electrically neutral, which means electromagnetism does not dominate its large-scale behavior. Einstein also knew nothing about the strong and weak nuclear forces (to be fair, nobody did), but those interactions only operate over very short distances.

Einstein’s Unexpected Dynamic Universe

For cosmology, gravity determines how matter behaves across enormous distances. If you imagine a collection of matter representing “a universe,” Einstein’s equations can tell you how that collection should evolve.

What Einstein found surprised him. General relativity did not naturally describe a universe that remained unchanged forever. Instead, the equations pointed toward a dynamic cosmos that would either expand or contract. That conclusion conflicted with the prevailing view at the time, which held that the universe was static and had remained essentially the same throughout cosmic history.

Einstein responded by adding a “cosmological constant” to his equations, represented by the Greek letter Lambda. General relativity already allowed such a term. In simple terms, it acts like a gravitational influence built into spacetime itself, one that can exist even in otherwise empty space. Depending on its value, that effect can produce either attraction or repulsion. Einstein selected a value that counteracted the gravitational pull of matter, allowing the universe to remain stable.

That solution did not last long.

An Expanding Universe Changes Everything

Within a few years, Edwin Hubble would discover that the universe is expanding. Meanwhile, theorists such as Russian cosmologist Alexander Friedmann took Einstein’s equations more literally and developed the theoretical foundation that would help support the Big Bang theory.

Einstein eventually abandoned the cosmological constant. He would later tell friends that introducing it had been his “greatest blunder.”

Then came another major surprise.

Fast forward to 1998. Two teams of astronomers were trying to resolve a long-running disagreement over how much matter the universe contained. Different observations had produced very different estimates, with some suggesting there was relatively little matter and others indicating much more.

Astronomers already knew that the universe was expanding. Because matter produces gravity, however, that matter should have been gradually slowing the expansion. By measuring how strongly the expansion was decelerating, researchers hoped to determine how much matter was actually out there.

Instead, they discovered the opposite.

The Universe Was Speeding Up

The expansion of the universe was not slowing. It was accelerating.

The observations still indicated that the universe contained relatively little matter, but even that matter was not enough to explain what astronomers were seeing. Something appeared to be pushing cosmic expansion to proceed faster over time.

The simplest explanation was a familiar one: Einstein’s cosmological constant. A constant background effect that produces cosmic repulsion could account for the observed acceleration. Decades after Einstein had discarded the idea, his supposed mistake returned as the leading explanation for the new data.

Dark Energy Reshapes Modern Cosmology

During the 1980s and 1990s, cosmologists had developed an increasingly sophisticated framework that became known as the Standard Model of Cosmology (physicists have a penchant for calling cohesive, collaborative, consensus models “Standard”). But the discovery that cosmic expansion was accelerating meant that model could no longer stand in its existing form.

Its replacement became our current best description of how the universe has evolved since the Big Bang: LCDM cosmology.

The Lambda refers to the cosmological constant, which is also known as dark energy. CDM stands for cold dark matter, the type of matter believed to account for most of the mass in nearly every galaxy. Cold dark matter is a story of its own. Here, the focus is Lambda.

A Remarkably Successful Model With a Problem

LCDM has been extraordinarily successful. It is also surprisingly simple, relying on only a handful of adjustable parameters and a small number of assumptions within the framework of general relativity.

Despite that simplicity, the model can account for an enormous range of observations. It describes the expansion history of the universe, the appearance of background radiation, the BAO feature, the growth of galaxies, the development of large-scale cosmic structure, and much more.

LCDM has become one of the most thoroughly studied and extensively tested theories in ALL of science.

And it is almost certainly wrong.

Researchers in the Food Microbial Sciences Unit at the University of Reading tracked the microbial and biochemical changes that occurred as three locally made Oxfordshire cheeses matured. Their findings suggest that some of the bacteria responsible for developing each cheese’s unique character may also be useful to the people who eat them.

The study, published in ACS Food Science & Technology, focused on three varieties made by Nettlebed Creamery in Oxfordshire. These included a soft white rind cheese aged for a little more than a week, a washed rind semi-soft cheese that matures over several weeks, and a semi-hard cheese aged in hay for about nine months.

Helpful Bacteria Shape Flavor and Texture

Lead author Sabrina Longley, a PhD researcher in the Department of Food and Nutritional Sciences, said: “Good cheese is delicious, and the artisan varieties we studied are full of microbial life that could have benefits to your gut health.

“The aging process creates more complex aromas and textures through the work of an army of helpful bacteria. The matrix of fats and proteins in the cheese may also help protect the bacteria as they travel along the digestive tract, making cheese an excellent vehicle for delivery of probiotics to the gut.”

To follow how the cheeses changed over time, the researchers collected samples at multiple stages of maturation and analyzed both their bacterial communities and chemical composition.

All three cheeses contained bacteria with recognized probiotic potential, meaning they may help support populations of beneficial microbes in the gut. Streptococcus thermophilus, which is also commonly used as a yogurt starter, remained dominant in the semi-soft and harder cheeses throughout the maturation process. Lactococcus lactis was detected in all three cheeses from start to finish.

The washed rind cheese and hay-aged cheese also contained Propionibacterium freudenreichii. This bacterium produces propionic acid, a compound associated with anti-inflammatory properties, reduced cholesterol synthesis, and appetite regulation.

Cheese Rinds May Have Prebiotic Potential

Cheese lovers who enjoy eating the rind may have another reason to do so. The white mold Penicillium candidum, which forms the characteristic rind on the soft cheese studied, produces chitin, a dietary fiber that may act as a prebiotic.

Prebiotics serve as food for beneficial bacteria in the gut, potentially encouraging positive changes in the gut microbiota.

The hay aging process also appeared to have a striking effect on the harder cheese. As it matured, the diversity of bacterial species increased substantially. The fully mature cheese contained nearly four times as many bacterial species as the same cheese did earlier in the aging process.

Mature Cheese Contained Very Little Lactose

The researchers also found that lactose, the sugar in cow’s milk that some people have difficulty digesting, was almost entirely absent from all three cheeses once they had matured.

During fermentation, lactic acid bacteria broke down most of the lactose, leaving very little behind by the time the cheeses were ready to eat.

Sabrina Longley is also a cheesemaker at the independent Nettlebed Creamery in Oxfordshire, which part-funded the research. She is carrying out her PhD research part-time with support from a University of Reading regional bursary, a program designed to help people from the local area pursue research studies.

The researchers caution that more work is still needed. Further research (dietary intervention trials) will be necessary to determine how these bacterial populations behave and change within the gut microbiota after the cheeses are consumed, as well as what effects they ultimately have on the human body.

In a randomized clinical trial involving adults with overweight, participants who followed an ad libitum low-fat vegan diet substantially reduced the number of calories per gram of food they consumed. Researchers found that greater reductions in energy density were tied to lower calorie intake and greater weight loss, despite the absence of any instructions to eat less.

“This helps answer a question people often have about plant-based eating: How can you lose weight without counting calories or going hungry?” said Hana Kahleova, MD, PhD, director of clinical research at the Physicians Committee for Responsible Medicine and lead author. “The answer is energy density. Plant foods are rich in water and fiber, so you can fill your plate, feel full, and still take in fewer calories.”

How the Low-Fat Vegan Diet Was Tested

The findings come from an analysis of a 16-week randomized trial involving adults with overweight. Participants were assigned either to an ad libitum low-fat vegan diet centered on fruits, vegetables, grains, and legumes, or to a control group that continued eating as usual without making any dietary changes.

Neither group was given a calorie target or told to limit how much they ate. Researchers measured each participant’s dietary energy density by comparing total daily energy intake with the total weight of food consumed, expressed as total energy (kcal per day) divided by total food weight (grams per day).

The study produced several notable findings:

• The total weight of food consumed did not change significantly in either group, meaning those following the vegan diet continued eating about the same amount of food by weight.
• Calorie intake declined in both groups, but the decrease was larger among those following the vegan diet, at about 357 kcal/day.
• Energy density remained essentially unchanged in the control group but fell by about 30% in the vegan group.
• Larger reductions in energy density were associated with greater weight loss, and that relationship remained even after researchers accounted for changes in calorie intake.

Same Amount of Food, Fewer Calories

The difference came largely from changes in the types of foods participants were eating. The vegan diet removed calorie-dense animal foods including meat, dairy, and eggs while increasing consumption of foods that provide more volume for relatively few calories, particularly vegetables and legumes.

Because these plant foods generally contain fewer calories per gram, participants could continue eating generous portions while taking in less energy overall.

“This isn’t about willpower or smaller portions,” Dr. Kahleova said. “It’s about choosing foods that naturally deliver fewer calories in every bite. A 30% reduction in energy density is a substantial shift that would be very hard to achieve and sustain through portion control alone.”

Why Energy Density Can Affect Weight Loss

Energy density refers to the number of calories contained in each gram of food. Scientists have studied it for years because it can influence how much people eat and how satisfied they feel after a meal.

Controlled feeding studies have shown that reducing the energy density of meals can help people feel full while lowering the amount of energy they consume. Importantly, the physical volume of food can remain similar even when the calorie content drops.

“When the foods you eat are lower in energy density, your body’s natural appetite signals work in your favor,” Dr. Kahleova said. “You eat until you’re satisfied, and you simply end up with fewer calories. That’s a sustainable way to manage weight.”

A Different Approach to Weight Management

Weight-loss advice often emphasizes calorie restriction and smaller portions. These findings point to another possible strategy: changing the composition of the food on the plate rather than simply reducing the amount of food eaten.

Choosing more water-rich, high-fiber plant foods may help people lower their calorie intake while still eating enough to feel satisfied. That could make weight management easier for some people by reducing the sense of deprivation that can come with traditional calorie-cutting approaches.

“From a clinical standpoint, targeting energy density offers a realistic strategy for weight loss,” Dr. Kahleova said. “Instead of telling people to eat less, we can help them eat differently — and the results follow.”

The Bottom Line

The findings suggest that a low-fat vegan diet can substantially reduce dietary energy density, allowing people to consume fewer calories and lose weight without intentionally restricting their calorie intake.

“You don’t have to eat less,” Dr. Kahleova said. “You can eat more food, feel full, and still lose weight — by choosing foods that are naturally lower in energy density.”

That question matters because microbial organisms dominated Earth for roughly 90 percent of the planet’s history. Reconstructing the transition from a world populated almost entirely by microbes to one filled with plants, animals, and fungi could also help scientists understand whether complex life might develop elsewhere in the universe.

From Microbes to Complex Life

Life originated on Earth more than 3.5 billion years ago, according to Ross Anderson, a paleontologist at the University of Oxford in the U.K. Cyanobacteria and oxygen-producing photosynthesis were present by at least 2.3 billion years ago, while eukaryotes had appeared by at least 1.7 billion years ago.

Algae followed at least one billion years ago and probably emerged even earlier. Animals appeared at least 570 million years ago, and possibly somewhat before that.

To reach the common ancestor shared by the plant and animal kingdoms, Anderson says researchers must look back to around 1.6 billion years ago.

Crown eukaryotes, which are among the earliest eukaryotic forms scientists are trying to trace, played a crucial role in the emergence of complex life on Earth. Anderson considers eukaryotes to represent the planet’s first complex life.

What Makes Eukaryotes Different?

Eukaryotic cells contain a nucleus that encloses their DNA. They also contain organelles, which are specialized structures inside the cell. One example is the mitochondrion, which helps provide the energy needed to support more demanding forms of life.

Eukaryotes ultimately gave rise to complex multicellular organisms and large visible life forms. Every animal, plant, and fungus around us today is eukaryotic.

Finding their earliest ancestors, however, is extremely difficult.

Organisms older than 500 million years did not yet possess shells or skeletons. Because those hard structures had not evolved, paleontologists must rely on rare environments capable of preserving fragile cells and soft tissues.

That leaves scientists with relatively little information about how life changed during an enormous span covering about 90 percent of Earth’s history.

Searching for the Transition to Multicellular Life

Anderson’s research focuses on one of the biggest transitions in biological history: how Earth changed from a planet dominated by bacteria into one inhabited by complex multicellular organisms.

Because fossils of these early multicellular organisms are difficult to find, he studies the chemistry of ancient rocks to identify the environments most likely to have preserved them.

Another major obstacle is time itself. Eukaryotic microfossils have endured billions of years of geological alteration and degradation, making already tiny remains even harder to detect.

Scientists do know that the transition from single-celled life to multicellular organisms happened more than once in different parts of the world. Anderson is particularly interested in understanding how that process eventually produced the remarkable diversity seen among animals today.

Much of the foundation for modern animal diversity appeared around the Ediacaran/Cambrian transition roughly 540 million years ago. This period marked a major evolutionary shift from predominantly soft-bodied organisms toward the Cambrian explosion, when animals with greater mobility, shells, and skeletons became increasingly prominent.

Where Scientists Search for Ancient Microfossils

Finding fossils from much earlier periods requires searching in places where delicate biological material had an unusual chance of surviving.

Anderson and his colleagues are especially interested in a roughly 100sq. km region near Svalbard, Norway. About 80 degrees North, this remote island area was once covered by a shallow sea.

Australia has also produced important evidence. Just last year, researchers there discovered some of the oldest known eukaryotic microfossils, dating to roughly 1.75 billion years ago.

Ancient coastal environments are especially promising places to search. Eukaryotes living in these settings would have had access to abundant nutrients and organic material, conditions that could have supported greater diversity and the development of multicellularity.

Researchers often target pristine locations or regions that have received relatively little scientific sampling. Anderson specializes in studying areas where enormous deposits of clay may have helped preserve ancient eukaryotic remains.

Today, many of the best places to conduct this work are deserts or Arctic landscapes. With little or no vegetation covering the ground, ancient rocks remain exposed and accessible.

Why the Fossil Hunt Is So Difficult

Even in ideal locations, finding eukaryotic microfossils is an enormous challenge. The organisms were microscopic, lacked protective hard tissues, and have been exposed to billions of years of geological degradation.

According to Anderson, one of the greatest problems is simply that the fossil record from this period remains poorly sampled.

Researchers are nevertheless making progress. Scientists are becoming better at identifying the types of rocks most likely to contain early fossils, providing new evidence that can help reconstruct the history of Earth’s earliest life.

What Earth’s Earliest Life Could Tell Us About Alien Life

The search has implications far beyond understanding Earth’s biological past.

Anderson says much of his work involving clay deposits was originally motivated by the search for life on other planets. By learning which environments preserve ancient organisms on Earth, scientists may become better equipped to recognize possible signs of life elsewhere.

Understanding how life emerged and became increasingly complex on our own planet is therefore an important part of astrobiology. If scientists want to estimate how likely life is to arise and evolve elsewhere, they first need a clearer picture of how that process unfolded here on Earth.