This missing period was a very important time in Earth's history, because it was just before and during the Cambrian explosion, which saw a huge diversification of life on Earth. The Great Unconformity is not only at the Grand Canyon; there are big gaps in the rock layers of that time across North America, the Baltic region of Europe and in northern China. Researchers have long debated why this unconformity exists.

Now, a new model of the movement of Earth's middle layer, the mantle, has revealed an explanation: The slow, heat-driven circulation of the mantle pushed these three regions upward during the time when the Great Unconformity was formed, according to new research published Nov. 4 in the journal Nature.

This uplift would have helped facilitate erosion, meaning sediments formed at that time sloughed off the continents and landed in the ocean. Importantly, the model also shows that in the past 540 million years, these same areas started sinking instead of rising, creating areas for sediments to get caught and then keep piling up in neat layers on the continents — marking the point where the Great Unconformity ends. This matches what geologists can see in North America, the Baltics and northern China.

"We looked at, where are the best places that the mantle would help create a Great Unconformity?" study co-author Nicolas Flament, a geoscientist at the University of Wollongong in Australia, told Live Science. "And these three places turned out to be three places where it's known to be quite extensive."

The cause of the Great Unconformity is hotly debated, with some arguing that a global deep freeze known as Snowball Earth could have shoveled sediment off the continents in this period. Glaciation probably played a major role in erosion, Flament said, but the new study suggests that the key driver was deep within the planet. Without the mantle pushing the continents upward, glaciers and other erosive forces would have had no slope to push sediments down, he said.

Constant flux

Earth is in a constant state of recycling crust through plate tectonics, said Shanan Peters, a geologist at the University of Wisconsin-Madison who was not involved in the study. Oceanic crust sinks back into the mantle through the process of subduction ‪—‬ when one tectonic plate dives beneath another. The chemicals it carries down with it get released back into the atmosphere via volcanic eruptions, linking the mantle with the atmosphere.

And tectonics aren't steady. As continents break up and join back together over eons, different materials get pushed into the crust. For example, the ancient Paleo-Tethys ocean, which lapped off the shores of the supercontinent Pangaea until it closed about 200 million years ago, was rich in carbon-bearing sediments that eroded from the continents, Peters, said. When the ocean floor was subducted back into the mantle, this carbon was pushed into the depths of the planet.

Today, in contrast, most of Earth's subduction is around the Pacific Rim, and much of the Pacific seafloor is remote from continents, the seafloor is relatively starved of carbon. What's getting pushed into the mantle now is therefore a different chemical composition than what existed 200 million years ago.

In that sense, referring to the Great Unconformity as "missing information" isn't accurate, Peters told Live Science. Instead, the absence of a rock record in those places at that time reveals something about the processes going on back then — and hints at how geology might have been affecting the atmosphere, and thus life's evolution.

The geological processes occurring during the time of the Great Unconformity may have set the stage for the Cambrian explosion, Peters said. For example, the crystalline rocks exposed on the surface at that time may have released elements like potassium, iron, manganese and carbon into the seas at an increased rate, prompting marine life to invent biomineralization — shells — in response and possibly shifting the composition of Earth's atmosphere to be more oxygen-rich, Peters said.

Flament agreed that the geological changes had significant knock-on effects for life. "It contributes to the environment in which complex life evolved," Flament said.

What's particularly interesting about the Great Unconformity is how it reveals not just a period of erosion but also a switch back to the deposition of sediments. The new paper provides an explanation for both, Peters said, and changes in the mantle are just the planetary-scale process to explain this big-picture phenomenon.

"This seems to me to be the only reasonable way to go back and forth between this state over time," he said.

There are still questions about what else the continents were doing in this time period. Peters leads an effort called Macrostrat that is pulling together observations of rock layers around the world, and Flament said he hopes that database will help ground-truth the new models' findings.

"So far in Africa and Russia, we don’t have as comprehensive a database," he said. "Once that is done, we can go and check whether the idea works."

'> The Grand Canyon is missing over a billion years of rocks. Now scientists know why.

If built, the sensor could measure the quantum effect known as frame dragging with the same precision as the best satellite experiments, but in minutes instead of years, the researchers proposed in a new study.

The research, published Sept. 17 in the journal Physical Review Letters, aimed to address a classic mismatch in physics. Picture a ring of clocks bolted to a spinning merry-go-round. You synchronize each clock with its neighbor around the ring. Then, you compare the last clock with the first. They don't match.

"It is impossible to synchronize that collection of clocks when you're in a rotating frame," Kai-Isaak Ellers, a physics graduate student at the University of California, Berkeley (UC Berkeley) and first author of the study, told Live Science.

Gravity's a drag

Einstein's theory of general relativity predicts that a massive, spinning object drags the fabric of space-time along with it, just like a spoon twirling in honey. The effect is clearly visible around supermassive objects, like the Milky Way's central black hole. But around Earth, the effect is very faint.

So far, scientists have measured Earth's frame dragging only from orbit. They tracked how the twisting of space-time slowly shifts spinning gyroscopes or the paths of satellites. In 2011, NASA's Gravity Probe B satellite, which carried four gyroscopes, confirmed Einstein's prediction with a margin of error of about 18%. Satellites tracked with lasers have since done even better. In July, researchers reported in the journal Nature that the LARES-2 satellite had shrunk that margin of error to just 0.2%.

However, that took about three years of laser tracking. Researchers also had to account for the fact that Earth bulges at the equator and its mass is spread unevenly, which gives the planet’s gravity small irregularities that tug on satellites far more strongly than frame dragging does. To subtract those tugs, the team relied on detailed maps of Earth's gravity made by other satellites.

Measuring frame dragging more precisely is a way to stress-test general relativity. Several alternative theories of gravity predict a slightly different amount of twisting, and a lab-based measurement would also be free of the modeling assumptions that satellite experiments depend on, Ellers said.

A quantum loop

The new device is a loop of superfluid helium-4 — helium chilled until it flows without friction and behaves like a single, giant quantum object. The loop is interrupted by a thin barrier riddled with tiny holes, called a Josephson junction. Superfluid helium can slip through the holes, but ordinary liquid helium cannot.

"That's where the quantum behavior comes from," said K. Birgitta Whaley, a quantum physicist at UC Berkeley and a co-author of the study.

As Earth spins and drags space-time, it nudges the quantum state of the helium flowing through the junction. That nudge shifts the frequency at which the helium sloshes back and forth in the loop, which the researchers could detect.

Superfluid devices, many of them built at UC Berkeley, have detected Earth's rotation since the late 1990s. But the helium-4 versions built around a Josephson junction, like the new design, have worked within about a hundredth of a degree of 2.17 K (minus 455.76 Fahrenheit, or minus 270.98 Celsius), the temperature at which helium-4 becomes a superfluid. At that temperature, a lingering fraction of "normal" helium mixed in with the superfluid adds noise.

Instead, the team calculated how the device would behave at a few thousandths of a degree above absolute zero. Below 0.7 K, the noise changed character, and the team found it drops sharply as the helium gets colder. One key finding in the new paper is the result of the team's thermal noise analysis, which showed how sensitive these devices could be at millikelvin temperatures, Elles said.

The catch is the barrier. Earlier helium-4 devices used holes about 90 nanometers wide. Working at these frigid temperatures demands much smaller holes, about 1 nanometer across ‪—‬ roughly the size of a helium atom. Keith Schwab, a physicist at Caltech and co-author of the study, and his collaborators are developing such materials, but they haven't been built into a working sensor yet.

If they can be, the researchers calculate that the device could measure frame dragging to 0.2% precision in about 35 minutes. If its vibrating membrane were made from the lowest-loss crystals, such as quartz or sapphire, that could drop to about one second, they said.

"This seems to be a very serendipitous discovery that at millikelvin, we can get this high sensitivity," Whaley told Live Science.

The signal corresponds to a time difference of about 10^-35 seconds between helium flowing one way around the loop and the other — the same mismatch as the clocks on the metaphorical merry-go-round.

"The interesting thing about it is just how small it is," Whaley said. "It's not so far off from the Planck time," about 10-⁴⁴ seconds, the shortest slice of time before the known laws of physics are expected to break down. This experiment is still a billion times too large to reach that limit, Whaley said. But future helium experiments could help explore whether time flows smoothly, like a ramp, or ticks forward in tiny, indivisible jumps, like the frames of a movie.

'> Physicists propose new quantum device to measure how Earth twists space-time

The species, Galerina indica, has been nicknamed the "dark magic mushroom" and was characterized in a study published Wednesday (Nov. 11) in the journal Current Biology.

"There is no species of mushroom anywhere, in any group, that has been known to produce both at the same time," study first author Andrew Kunik, a fungal biology researcher at the University of Florida, told Live Science. "So it's quite remarkable."

Exactly why the dark magic mushroom has evolved to contain these two compounds is unclear, but the authors told Live Science that they may give the fungus a powerful defense against being eaten.

Common evolutionary trick, rare combination

The ability to produce either psychedelic or toxic chemicals has evolved multiple times across fungal lineages. A process called horizontal gene transfer, which is widespread among fungi, has played a part in that process.

In horizontal gene transfer an organism passes new genetic material to another, as opposed to vertical gene transfer, in which a parent passes genetic material to offspring. It can lead to unexpected genetic combinations and, in bacteria, plays a key role in the development of antibiotic resistance.

Some of the world's deadliest mushrooms, from the Amanita genus, stop cells from producing proteins and can cause death through liver failure. Past work has shown these mushrooms shared the ability to produce their poisonous amatoxins via horizontal gene transfer with mushrooms from the unrelated genera Galerina and Lepiota. Some mushrooms have acquired the ability to produce psilocybin via horizontal gene transfer as well.

But Kunik and colleagues weren't looking for specific chemicals when they began hunting for Galerina mushrooms in the swamps of Florida; they just wanted to learn more about the mushrooms' chemical makeup, as not all Florida Galerina mushrooms had been characterized before.

They collected five specimens from Galerina, a genus that contains over 300 species worldwide, many of which are poisonous. Among the samples they collected were small G. indica specimens that grew on moss-covered palm trunks. The largest mushrooms were only about 0.2 inches (0.5 centimeters) tall, with caps up to about 0.1 inches (0.25 cm) wide.

Chemical analyses revealed that the dark magic mushroom contained both psilocybin and amatoxins, including one amatoxin that had never been documented in mushrooms. The new amatoxin wasn't wholly unexpected, given that other species of Galerina produce closely related amatoxins, Kunik said.

The production of psilocybin alongside the amatoxins was more of a surprise for the research team.

"To find them both together in one mushroom, I never expected to find that," study co-author Matthew E. Smith, a plant pathologist at the University of Florida, told Live Science. "We were shocked."

To understand how the tiny, deadly mushroom acquired its mind-altering, liver-poisoning abilities, the team compared the genes of G. indica with those of other psilocybin-producing mushrooms, finding the genes shared a common evolutionary origin — even though the mushrooms themselves are distantly related.

The researchers also found G. indica’s psilocybin-producing genes are arranged in a different order than in other psilocybin-producing fungi, which suggests the gene cluster was rearranged during its evolutionary history, a clue that horizontal gene transfer happened.

Gene jumping and swapping

G. indica seems to have acquired the ability to produce psilocybin via horizontal gene transfer from unrelated fungi about 15.5 million years ago, based on reconstructions of Galerina’s evolutionary history from DNA analysis, Smith said. However, it’s possible that psilocybin-producing genes entered the lineage through two separate horizontal gene transfer events, possibly as recently as 6 million years ago, Kunik noted. Collecting and sequencing more Galerina specimens could help untangle their evolutionary history.

The findings are surprising, said Hannah Reynolds, a fungal ecologist at Western Connecticut State University who was not involved with the new research. "What was exciting about this paper was seeing both of these [compounds] present, seeing that this gene cluster jumped in, got rearranged, maybe came in twice — it's very cool," Reynolds told Live Science.

The ability to produce two types of incapacitating chemicals could form a powerful defense against being eaten, because organisms that would normally eat them would have difficulty evolving defenses against both, Kunik speculated.

But the idea that this duo of compounds prevents the mushroom from being eaten is just a hypothesis. To buttress that idea, further research might tweak the genes of the dark magic mushroom to observe how removing one compound affects the species' role in the food web, Kunik suggested.

Tropical and subtropical mushrooms are historically understudied, so there is likely much more incredible fungal diversity right under our feet, Smith said.

'> Florida's 'dark magic' mushrooms have a deadly combination of chemicals never seen before

Rubino recently chaired a team of 56 experts that was assembled to better define obesity and develop new diagnostic criteria for the condition. First proposed in January 2025, their new framework includes more body measurements beyond BMI and distinguishes between "preclinical" and "clinical" obesity.

Now, a new study published Wednesday (Nov. 11) in the journal Nature confirms that these new criteria could detect obesity with greater precision than BMI alone. In other words, with the new approach, more people would be accurately diagnosed with obesity and fewer people would be misdiagnosed than are with BMI alone.

Live Science spoke with Rubino and other experts to break down the new findings and learn what they mean for patients.

What are the limitations of BMI?

At the simplest level, obesity is excess body fat. There are special scans and exams that send weak electrical signals through the body to measure a person's body fat percentage directly, but criteria based on body measurements are more accessible across clinical settings.

BMI is the most common of these measurements, as it simply involves dividing a person's weight by their height squared. However, it does not account for individual differences in lean muscle mass or bone density.

Additionally, the different BMI categories — such as "overweight" and "obese" — don't carry the same risks for all patients. Certain racial and ethnic groups tend to experience health consequences, such as higher mortality rates, at different BMI levels than others do.

What metrics does the new obesity definition use?

For a given patient being assessed for obesity, the proposed guidelines would suggest using at least one additional body measurement alongside BMI and having their doctor review their medical history for other signs of bodily or organ dysfunction.

The proposed body measurements are less influenced by a person's muscle mass or bone structure than BMI is. They include waist circumference, waist-to-hip ratio and waist-to-height ratio. Notably, because different ethnicities are associated with different fat distribution patterns in the body, the latest Nature study incorporated different waist circumference cutoffs based that varied by ethnicity.

In addition to these body measurements, the proposed criteria look at 18 conditions and signs of bodily or organ dysfunction that are related to obesity, such as cardiovascular diseases, joint pain and sleep apnea. (All 18 factors can be found detailed in this chart.)

What is the difference between preclinical and clinical obesity?

Rubino and his colleagues — which together made up what's known as a Lancet Commission — defined "clinical obesity" as a disease state involving at least one of 18 forms of bodily dysfunction caused by excess fat tissue. Preclinical obesity, by contrast, is when a person is at risk of this disease state and may need interventions to avoid obesity-related dysfunction.

That means that two people with the same BMI, waist circumference and waist-to-height ratio may be classified differently, depending on whether they have other conditions. In the new study, between 77% and 91% of individuals with preclinical obesity did not progress to clinical obesity within 10 years, depending on the cohort analyzed.

This distinction can be complicated, though, as the diagnostic metrics for each form of dysfunction contain their own ambiguities.

"There needs to be more consensus on what's actually defining clinical obesity," said Dr. Aayush Visaria, an internal medicine instructor at Rutgers Robert Wood Johnson Medical School in New Jersey. Visaira was not involved in writing the new criteria but authored an analysis of the proposed measures.

The Lancet Commission argues that the categories of preclinical and clinical obesity could help doctors identify the people with the greatest need for treatment. The researchers tracked health outcomes using electronic health records from China, the United Kingdom, the United States and Spain, and they determined that their clinical obesity classification was better at flagging people's risk of death than BMI alone.

They found no clear association between BMI and mortality risk, but clinical obesity was linked to a 69% greater risk of all-cause mortality, compared to no obesity.

Would the new criteria affect the overall prevalence of obesity?

The Lancet Commission's approach could drive a small net uptick in individuals diagnosed with obesity, according to the new study.

Under the current framework, "we are definitely missing some people who actually need obesity treatment but just did not meet the BMI criteria," said Dr. Jennifer Hwang, an instructor of medicine at the University of Chicago who has published her own analysis of the new criteria.

With the BMI-only approach, people with BMIs of 30 or higher are categorized as obese. With the new definition, some people with BMIs under 30 would be newly categorized as clinically obese, while a smaller group of people with high BMIs would suddenly not count as clinically obese, the Nature study predicted.

For instance, the former group might include people who have "overweight" BMIs but also have obesity-related dysfunction, while the latter group might include people with "obese" BMIs but without any dysfunction.

Overall, the new criteria would increase obesity prevalence by about 3.3% to 7.4%, the team predicted. The percentage varied depending on the group analyzed.

What would it take to implement this new definition?

More research is needed to prove that the Lancet Commission's criteria would improve patient care and be practical to use in a clinical setting, Hwang said. She noted potential challenges in implementing both new aspects of the new framework. While the body measurements sound simple enough to use, clinicians would need training to perform them accurately.

Providers also may struggle with the new distinction between preclinical and clinical obesity. A 2025 analysis of the Lancet Commission framework noted that some patients who qualify for obesity medications under the Food and Drug Administration's guidelines may be recharacterized as having preclinical obesity and no longer receive a prescription.

Rubino and the rest of the Lancet Commission plan to continue validating their framework to see how it could best support personalized obesity treatment. For instance, they want to determine which forms of organ dysfunction are of greatest concern and develop a way of scoring each patient's level of risk.

This article is for informational purposes only and is not meant to offer medical advice.

Help us improve Live Science Pro: We're always trying to make our content better. Leave us feedback about Pro here.

'> More people could count as obese under newly proposed definition — here's what you need to know Nancy Grace Roman Space Telescope is nearing its final destination more than 1 million miles (1.6 million kilometers) from Earth, where it will soon scour the universe for a host of cosmological treasures, including an estimated 100,000 new alien worlds.

But even before its mission truly begins, recent developments suggest the state-of-the-art spacecraft could take better images than — and remain operational for more than twice as long as — initially expected, further delighting already-excited astronomers.

"It is fantastic to learn that Roman is not just reaching its design goals but exceeding them," Eamonn Kerins, an astronomer at the University of Manchester in the U.K. who will help lead one of Roman's major surveys, told Live Science.

Roman is NASA's latest flagship space telescope, following in the footsteps of iconic observatories like the Hubble Space Telescope and the James Webb Space Telescope (JWST). The $4 billion machine ‪—‬ which is over 42 feet (12.7 meters) long and weighs around the same as a fully grown Tyrannosaurus rex ‪—‬ successfully launched into space on Aug. 30, more than a decade after scientists started building it.

The telescope is now en route to Lagrange point 2 (L2), a fixed point relative to our planet where Earth's gravity and the sun's gravity cancel each other out. There, Roman will join several other important spacecraft, including JWST and the European Space Agency's Euclid telescope.

During Roman's journey to L2, which is currently around 85% complete, mission scientists have remotely switched on the telescope's various instruments to test whether they function as expected. So far, this "commissioning process" has gone off without a hitch, and by the time Roman arrives in less than two weeks, it should be ready to snap its first in-depth images of the cosmos.

Researchers were already pumped to see what Roman will be able to do once it is in place and fully switched on. However, that excitement has further intensified in recent weeks, thanks to two postlaunch developments.

First, a series of near-perfect rocket burns, executed during and shortly after launch, saved more than a decade's worth of fuel that can now be used to extend Roman's mission. Second, after remotely adjusting the telescope's mirror, researchers discovered it should be capable of snapping images with around 30% greater detail than engineers predicted.

The team that designed, launched and remotely commissioned the orbital observatory has "done an amazing job" and "their work has ensured that Roman is more than up to the task," Kerins said.

Extended lifespan

Shortly after Roman arrived in space on board a SpaceX Falcon Heavy rocket that lifted off from NASA's Kennedy Space Center in Florida, mission scientists conducted two major burns, or engine firings, which gave the spacecraft enough momentum to escape Earth's orbit and make the journey to L2.

Thanks to a combination of "exquisite planning by our orbital dynamics team" and "brilliant execution by the operations team," these burns were so precise that each one saved up to four years' worth of fuel, Jamie Dunn, director of NASA's Goddard Space Flight Center in Greenbelt, Maryland, said in a Sept. 14 statement.

On top of this, Roman ended up being much lighter than initially planned, which allowed engineers to pack another four years' worth of fuel into the spacecraft before launch. "Since Roman's [weight] was lower than we budgeted for, we were able to fill the propellant tanks to their capacity rather than only filling them as much as we needed," Alison Rao, the Roman propulsion lead at NASA Goddard, said in the statement.

In total, these savings could give Roman an additional 12 years of fuel, which could more than double the mission's planned 10-year lifespan. That means Roman could still be capturing images of the cosmos in 2048.

Given that Roman can collect data up to 1,000 times faster than Hubble, this extended lifespan will greatly enhance the amount of data the new space telescope will be able to capture. "With a 20-year Roman lifetime, we could, in theory, do over 20,000 years of Hubble survey work," Kerins said. "That's a lot of science!"

This prolonged lifespan will let astronomers compare images of specific objects decades apart — such as expanding nebulas or colliding galaxies — allowing them to detect changes they otherwise might have missed.

It may also let them study objects or phenomena that we haven't even discovered yet, which is particularly exciting, Kerins noted. "The real show-stopper results will be new things we just aren't even thinking about right now," he said. "The possibilities are truly breathtaking."

There is also the chance that Roman's mission could be extended even further, because engineers often find clever ways of making active spacecraft last longer. For example, Hubble is more than two decades past its initial mission parameters, and the recently deceased Swift Observatory lasted 10 times longer than initially predicted before falling back to Earth last week.

Improved image quality

Roman's secret weapon is arguably its Wide Field Instrument (WFI), made up of a 288-megapixel camera attached to a 7.9-foot (2.4 m) mirror, which will capture ultra-detailed images with a field of view roughly 100 times larger than Hubble's.

We have already seen the first WFI images — a series of blurry, green dots captured during a test of the instrument's 18 different light detectors ( see below). However, those photos were nothing like what WFI will capture in the future; those images will be so detailed that you would need dozens of high-definition TVs to properly display a single snap in full resolution, Kerins said.

After Roman completes the initial WFI commissioning phase, those images will be around 30% sharper than designers predicted. "All of the images from Roman's cosmic surveys will be even sharper than we expected," Alden Jurling, a senior optical engineer who works on Roman at NASA Goddard, said in an Oct. 14 statement. "It's a great outcome."

The improvements were first noticed after the WFI's car-sized mirror was realigned by just one-sixteenth the diameter of a human hair, demonstrating just how intricate the commissioning process has been. "Calibrating an instrument is like tuning a piano or guitar before a concert," Maxime Rizzo, a WFI systems engineer at NASA Goddard, said in the statement. "You adjust everything until it's just how you want it and then leave the settings alone so it performs consistently while you use it."

The improved image quality could really come to the fore during Roman's hunt for potentially habitable exoplanets, which is what Live Science's readers are most excited about for this mission.

Kerins, who is leading the Exoplanet Demographics Working Group for the Transits in the Roman Exoplanets Survey, is particularly excited about this development, but he said it does not necessarily guarantee that Roman will find more exoplanets than initially predicted.

"A remarkable achievement"

The rest of Roman's commissioning phase is also proceeding as planned.

Roman's coronagraph instrument, which will block out the light from distant stars to allow WFI to spot alien worlds, has passed its main commissioning phase and is working as intended, according to a NASA blog post.

Meanwhile, a global network of ground stations, which will receive up to 1.4 terabytes of data from Roman every day, has established contact with the spacecraft and is receiving signals as expected, another blog post revealed.

All of these early wins raise hopes that Roman can have a long and successful career, and are a testament to the years of work that went into designing the spacecraft and planning the mission.

"What we're seeing now with the actual optical performance and estimated lifetime of Roman is just how good that design process has been," Kerins said. "It's a remarkable achievement. I can't wait to see what Roman is going to give us."

'> 'The possibilities are truly breathtaking': NASA's Roman Space Telescope will take better images and last longer than experts predicted