from the University of Oslo's Museum of Cultural History.
"Here we have a coin bearing the king's portrait and a cross, with another cross on the reverse," University of Oslo coin expert Svein Gullbekk said in the statement. "It is a Christianisation coin on a grand scale."
Olaf is credited with establishing Christianity in Norway — an early step toward its full conversion about a generation later.
"We can see how King Olaf used coinage to legitimise the new faith and to establish himself as a Christian king of European standing," Gullbekk said. "This is branding."
Haraldsson learned about Christianity when he joined Viking raids against England and France as a young man, and he was baptized in the French city of Rouen in about 1013, according to the statement.
He became Norway's king in 1015, and in about 1024 proclaimed that only Christianity would be legal, according to the University of Bergen. Much of Norway, however, remained faithful to the Norse gods during his rule, especially around the central Trøndelag region and in the eastern parts of the country.
But Olaf was made a Christian saint shortly after his death in 1030. He is now recognized as one of the first Christian kings of Norway and the first Norwegian king to issue coins in his own name.
"I could see that it read ONLAF R+ NORMANORV. … Could this really be a coin of Olaf Haraldsson that I was holding?" Skogsfjord said in the statement. "And it was! It was a very special moment."
The coin was struck between about 1024 and 1028, near the end of the Viking Age, and circulated for 20 to 25 years before someone deposited it in the hoard, the statement said.
Although the minting of the coin was a political and religious act, the coin also seems to have been used as currency; both sides bear numerous small cut marks, which was a common way of determining whether a coin was made completely of silver.
Gullbekk said Haraldsson himself had decided what the coins would look like and may have been present when they were minted.
"It is entirely possible that this very coin from Mørstad was once held in the king's own hand," he said in the statement.
'> Extremely rare Viking Age coin from the reign of 'Olaf the Holy' may have been 'held in the king's own hand'
The German physicist Werner Heisenberg wrote in 1947 that the reactor for the "Nazi bomb" project — which culminated in Germany's B8 nuclear reactor — was almost finished at the end of World War II.
Heisenberg, who led the reactor's development, claimed the reactor was "just insufficient" to create a self-sustaining fission reaction and that it lacked only a "relatively small amount of uranium" to work.
If it had worked, the B8 reactor would have confirmed that a fission chain reaction was possible, marking a key step toward the German development of an atomic bomb. It could have also spurred the development of specialized fission reactors used to create weapons-grade plutonium from uranium. Instead, the atomic bomb was developed first by the United States and was used to force the surrender of Japan in August 1945. (Germany had already surrendered in May 1945.)
The new study, published Sept. 29 in the journal PNAS Nexus, used historical documents and forensic investigations of two of the project's surviving uranium cubes to refute Heisenberg's claim. The new research indicates that the German B8 reactor had less than half the amount of "heavy water" and about half the amount of uranium it would have needed for a continuous chain reaction.
"My results argue that Heisenberg was off by roughly a factor of two," said first author Patrick Park, a doctoral student at Princeton University who co-wrote the study while at Columbia University.
Park said Heisenberg's mistake was understandable: His calculations were only approximate, and the project was relocated to a rock cellar in the town of Haigerloch, Germany, after Berlin was bombed.
My results argue that Heisenberg was off by roughly a factor of two.
Patrick Park, doctoral student at Princeton University
"People were dying or starving and so these reactor calculations were not his first priority," while many details of neutron physics were unknown at that time, Park told Live Science in an email. "Given these circumstances, I think he did the best he could."
Heavy water
To answer the question of how far the reactor for the Nazi bomb project got, the scientists began by tracing archival records of hundreds of uranium cubes that had been used by German scientists. The B8 reactor consisted of five concentric circles of uranium cubes suspended on chains within the heavy water tank. The German scientists planned to place a radium-beryllium neutron source into the reactor's core to kick-start the chain reaction with a flood of neutrons that would split the uranium nuclei and release more neutrons, furthering the chain reaction.
Heavy water is a form of water that contains the neutron-heavy hydrogen isotope deuterium. Like the mainly-graphite blocks and rods used in many reactors, it can be used to "moderate" or slow down fast neutrons created in a fission reaction so they trigger fission — and more neutrons — in nearby uranium atoms. The Germans also used small amounts of graphite in their reactor, but as a coating to reflect neutrons back into the chamber.
A cube of natural uranium from the German atomic bomb project. (Image credit: John T. Consoli, University of Maryland College Park, MD.)By combining the records of the cubes, heavy water and graphite used by the German scientists with measurements of the two surviving cubes, the study authors created a mathematical model of the reactor that agreed closely with historical measurements. This enabled them to establish that the heavy water reactor was far from achieving a stable reaction. The findings also helped them examine the suggestion that the Germans should have instead built a graphite-based reactor like the nuclear pile developed at the University of Chicago to build the American bomb.
But the study authors determined that a graphite-moderated reactor was unfeasible in wartime Germany because the local supply of coal available to create graphite contained high levels of neutron-absorbing boron, making it useless.
Instead, the heavy water used in the B8 reactor was produced at a single factory in Norway, which was occupied by Germany from April 1940 until May 1945. However, the reactor contained only about 370 gallons (1,400 liters) of heavy water, instead of the more than 780 gallons (roughly 3,000 liters) it would have needed, the researchers determined.
Heavy water makes up a tiny fraction of a percent of ordinary water, and extracting it by electrolysis in the Norwegian factory took extraordinary effort. The factory was producing as much heavy water as it could, but the B8 reactor would have needed more than twice the amount it produced during the entire war, the researchers wrote.
Another finding is that the B8 reactor had about half the amount of uranium it would have needed to sustain a fission chain reaction. The reactor contained a total of 664 cubes, each weighing about 5.11 pounds (2.32 kilograms), for a total of 3,390 pounds (1,540 kilograms) of uranium. Similar cubes were distributed among other experimental groups, giving a total inventory in wartime Germany of about 1,100 cubes of uranium.
But the researchers determined that the B8 reactor would have needed at least 1,200 cubes to work. Germany, therefore, was not about to develop a reactor for an atomic bomb in 1945. Contrary to Heisenberg's claims, the heavy-water reactor was not nearly ready, and a working graphite reactor was impossible.
"We conclude Germany could not have built heavy water nor graphite reactors during World War II," the researchers wrote.
Mark Walker, a historian at Union College in Schenectady, New York, who wasn't involved in the study, said the findings explain Germany's decision to develop a heavy-water reactor, since a graphite reactor was not feasible and they didn't know at the time how much heavy water would be needed.
Walker is the author of "Hitler's Atomic Bomb: History, Legend, and the Twin Legacies of Auschwitz and Hiroshima" (Cambridge University Press, 2024) and a noted expert on Germany's wartime nuclear efforts. He agreed that Germany could not have made a graphite reactor during World War II.
"This paper argues that if the Germans had done something they did not do, then this would have failed," he told Live Science in an email. "While this is counterfactual history, it is an interesting engineering analysis."
'> Uranium from World War II reveals how close the Nazis were to an atomic bomb Rutherford is the founder and executive director of the nonprofit environmental organization Ocean Research Project, which gathers and analyzes marine data from a sailboat. His route took him around the southern tip of Greenland, through the Denmark Strait and into the Greenland Sea. From there, he sailed through the Norwegian and Barents seas, and reached Russia's Novaya Zemlya archipelago in mid-August.
He was planning to continue to Canada and end his journey where it started, but Russian officials halted him in his tracks and ordered him to turn around.
On his way home, Rutherford told Live Science about his adventures and why he wants to complete this loop. In an interview on Sept. 23, he also revealed what he'll do differently on his next attempt to avoid another Russian interception.
Sascha Pare: Where are you currently, and what are the conditions like?
Matt Rutherford: I'm about halfway between Greenland and Newfoundland in the Labrador Sea. The conditions aren't too bad; I mean, it's close to a gale, but it's not quite a gale. [Editor's note: A gale is defined as an area of sustained surface winds of 34 to 47 knots (39 to 54 miles per hour).] It's just a little hard to do anything. I've got dishes in the sink that are all wedged in there that I really need to deal with — but I don't feel like it, because you're just getting tossed around. Waves are crashing on the cockpit. Normally, I do video calls under a dodger [a canvas screen on a boat or ship that provides protection from spray], and you can see the ocean in the background… But I'm going to get hit by a wave if I do that.
SP: You're sailing home to Maryland after a rather perilous expedition. How long have you been at sea for?
MR: I left in mid-May, and I've been basically underway for the most part since then. At this time, currently, I've only been at sea for a few days, because I left Greenland a few days ago. The longest stretch I was continuously at sea this year is 59 days, although I was planning on doing longer than that, so that sucked. Essentially, I was attempting to do a nonstop, single-handed circumnavigation of the Arctic. That's where this all sort of came out of. I tried in 2018, but you couldn't get the Russian permits. And the Russians were the problem in the end [this year]. I got defeated by Russian bureaucracy, essentially. And there was some weird stuff going on with the ice up there this year. [Editor's note: Sections of the High Arctic were impassable due to a relatively cold summer and solid ice fields.]
Rutherford's route took him close to Russia's coast, where the FSB intercepted him. (Image credit: Ocean Research Project) SP: What happened with the Russians that forced you to turn back?
MR: The FSB got me. [Editor's note: The Federal Security Service (FSB) is Russia's main security agency and a successor to the Soviet Union's KGB.] They boarded me twice, actually. I've never been boarded in the ocean in my life, and I've been sailing 20 years, all over the place. I got about 1,000 miles [1,600 kilometers] into Russia, roughly. I got into the Northern Sea Route. If you just draw a line due north, I was due north of West China — it was way over there, about halfway around the world in the Arctic. I made it about halfway, because I started in Aasiaat, Greenland.
They boarded me once, and then they turned me around and boarded me again. It's a bit of a strange situation, I guess. Two days after I turned around, the ice that I was waiting to open opened, and I sent them an email — the NSRA, the Northern Sea Route Association in Moscow — and said, "Hey, it's open. Can I pretty please go?" And they just got mad at me, like, "You'll be in violation of your permit; you have to turn around."
SP: You're planning to try the circumnavigation again next year. Will you do anything differently to make sure you complete it?
MR: The boat's pretty good to go — which is great, because that's a huge time sink. Ideally, hopefully, if I can get north of [the Norwegian archipelago] Svalbard again like I did this year, then I'm going to stay north of [the Russian archipelago] Franz Josef Land, and I'm going to basically ride the polar ice cap all the way from Svalbard to the Northwest Passage — all the way to Alaska and beyond, essentially.
Because I've learned how the FSB operate, and I know where they're keeping their ships now. Even though I was north of Novaya Zemlya, they still were able to get me. But if I'm over there, north of Frank Josef, they don't go that far, so they won't be able to get me up there. I've figured out a couple of other things that I'm not even going to say, honestly — there are workarounds to get them to [leave me alone]. I'm going to go a little bit quiet.
The NSRA gives you the permit to do this, but the FSB are the people who patrol it. And the FSB don't like the NSRA. I learned that when they boarded me, because they think that they're the ones who should control the Northern Sea Route, not the NSRA. So there's [a] beef between them; they don't talk. There's a lack of communication, which benefits me. I can lean heavy onto the NSRA side, because they don't have boats; they're not going to board you. And they're the ones you have to check in with every 24 hours in Moscow; you've got to send them an email every 24 hours. So I'll do all of that stuff with those guys, but I think there's some ways I can avoid the FSB even knowing where I am, essentially, while still complying with my permit in the NSRA.
Basically, I've got to do the Northern Sea Route without getting within 12 miles [19 km] of any Russian land, period — even a little island, even a rock that sticks out that's 10 feet by 10 feet [3 by 3 m]. That's going to be real tricky, because there are a lot of little islands down there. But the FSB is mostly on the European side; they have almost no boats over on the east side or the middle. So if you can get past the European side by hugging the coast way the hell north, hopefully I can get past where they patrol, and then I can just shoot on through.
Nobody else in the world does this — nobody else in the Arctic, nobody else anywhere. There's literally no other body of water on Earth where you've got to get permits, and then you've got to get boarded like this. It's only Russia, and only north of Russia. And that's because there's a huge amount of natural gas, they think, buried above Russia. So Russia's trying to claim everything to the North Pole.
Technically, it's international waters, so the U.N. is like, "No, this is not right." And Russia's like, "Whatcha gonna do about it?" It's kind of hard to argue with that — and it's north of Russia, so nobody else is there. They've got free rein, and they've got all the icebreakers and whatever else.
Everything else is about the same. I need to secure my hot sauce better, because every time I open my cabinet, they fall out all over the place. There's little things like that — quality-of-life things. I'll probably bring some more heated socks — electric socks and electric gloves. I'll try to make better videos — but I'm not a content creator, and I don't want to be an influencer.
Rutherford will make another attempt at circumnavigating the Arctic next year. (Image credit: Matt Rutherford)SP: Can you tell me a bit about your background and what led you to this point?
MR: I did this whole circumnavigation of the Americas — nonstop, single-handed — back in 2011 where I spent 309 days alone at sea on this little 27-foot (8 meters) boat. When I got back from that big, crazy trip — which I made a documentary about ["Red Dot on the Ocean: The Matt Rutherford Story"] — I created a nonprofit called Ocean Research Project, where, basically, we use sailboats to do research. We focused mostly in 2013 and 2014 on garbage-patch-related microplastics. In 2013, we mapped out the eastern side of the Atlantic garbage patch, because nobody had got to the eastern side of it. I think it was 160,000 pieces per square kilometer, or something like that. And then, we did some stuff in 2014 in the Pacific garbage patch with the University of Tokyo; we did a joint paper with them.
But mostly what we focus on is Arctic research. Since 2015, we've been heading up to Greenland — sometimes the Northwest Passage also, but primarily Greenland — doing research related to glaciers, for the most part. An ocean-terminating glacier sort of has a river of melted water underneath it, and it creates upwelling, and the upwelling has nutrients. So it mixes nutrients with the ocean and creates this perfect recipe for growth for phytoplankton and zooplankton. And then, we look at the different stages of decay between an ocean-terminating glacier, a land-retreated glacier or a deglaciated fjord. In the middle phase, when a glacier starts retreating back on land, it just creates a river of muddy water, essentially; it turns the fjord into a mud puddle. You can't have photosynthesis if you're in a mud puddle.
The Ocean Research Project is a nonprofit studying the Arctic and Chesapeake Bay. (Image credit: Matt Rutherford)SP: Have you been collecting samples or data on this expedition?
MR: Well, it's a little tricky on a boat under these circumstances. I took 50 samples, which were just water samples, and those were from Newfoundland to Aasiaat, Greenland. Nicole [Nicole Trenholm, Ocean Research Project's science director] has a NASA internship out at JPL [Jet Propulsion Laboratory]. She was publishing a paper looking at their model that they have [ECCO-Darwin], and I've kind of forced my way into the paper — well, the organization did, with Nicole's help — by adding these samples. Now we have in situ data, physical data, that we can compare to the model data. That was the only thing we did this year. It's a couple-thousand-mile stretch with 50 water samples in it, so it's a pretty straightforward sort of thing.
Nicole is trying to publish multiple peer-reviewed scientific papers from our previous data. She's got a traffic jam of data, so she needed some time to finish publishing papers from stuff we've collected over the last few years. There is no money anyways. I could still grab some samples on the way up there [Greenland]. And it's trying to promote the nonprofit through it, because people will pay a lot more attention to this stuff than they pay to traditional research expeditions.
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SP: What are your hopes for the Ocean Research Project once you tick off this goal?
MR: Basically, we're trying to expand the organization over the next couple of years. I'd like to bring in another one or two more scientists, because we're up there for three months in Greenland, and sometimes we go to the Northwest Passage — and it's a lot for one scientist.
The big problem we're having is that when Elon Musk was part of DOGE [U.S. Department of Government Efficiency], they cut a massive amount of polar funding — something like 88% of it — because apparently climate change is a hoax and they hate it and you're not allowed to research it either, right?
Basically, nobody's got money. We don't typically get NSF [National Science Foundation] funding; we get more foundation funding, because it's hard to get NSF funding, even before all this stuff. Now that the funding has been cut on the governmental level, a lot more scientists are going after the foundation grants that we used to have a lot less competition for. That makes it a little tricky, too, because now they're getting a flood of requests that they didn't usually get in the past.
This interview has been condensed and edited lightly for clarity.
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'> 'The Russians were the problem in the end': Sailor Matt Rutherford on being intercepted by the FSB while attempting to circumnavigate the Arctic O....
Neutron stars are the collapsed cores of massive stars that exploded as supernovas. Each packs more mass than the sun into a ball roughly 12 miles (20 kilometers) in diameter. Some, called pulsars, spin rapidly and sweep beams of radio waves across the sky like cosmic lighthouses. Their rotation is so steady that their pulses work as extraordinarily precise clocks.
Very few pulsars orbit another neutron star. "There are only 30 such double neutron star systems, and the relativistic effects are very strong if they are in compact orbits," study co-author JinLin Han, an astronomer at the National Astronomical Observatories of the Chinese Academy of Sciences, told Live Science via email.
The first such pair, discovered in 1974 and known as the Hulse-Taylor binary, provided the first evidence for gravitational waves — ripples in space-time predicted by Einstein. Such waves carry energy away from an orbiting pair, so its orbit should gradually shrink, and the Hulse-Taylor orbit shrank at just the rate Einstein's theory predicted.
Later, the "double pulsar," which completes an orbit every 2.45 hours, matched the predicted rate to within about 0.01%. Eventually, this shrinking forces such pairs to merge, unleashing gravitational waves like those the Laser Interferometer Gravitational-Wave Observatory and Virgo interferometer picked up in 2017.
The new system, designated PSR J1856-0039, lies roughly 4,200 to 6,500 light-years from Earth. In 2020, it turned up in a survey of the Milky Way's disk by China's Five-hundred-meter Aperture Spherical Radio Telescope (FAST), the world's largest single-dish radio telescope.
"We have discovered about 900 pulsars," Han said of his team's work. "After a few follow-up observations, this one is very extraordinary."
The pulsar spins about 43 times per second, and the two stars are separated by roughly twice the distance between Earth and the moon. But the "most attractive feature" is the short orbital period of about 2.36 hours, Han said. "This is the second-shortest one, and it must show stronger relativistic effects than the famous double pulsar and the Hulse-Taylor system."
The team observed the pair with FAST 17 times between 2020 and 2025, sometimes long enough to cover a whole orbit. The researchers measured the arrival times of the system's pulses and then fit that data to orbital models that accounted for relativistic effects, like subtle changes to the pulse arrival times at different parts of the stars' orbits.
"With so many measurements by FAST, which would be hard to match in accuracy with other telescopes, we got not only the basic parameters of the pulsar and its orbit but also three relativistic effects," Han said.
First, the orbit is shrinking as the stars radiate gravitational waves, drawing them about 9 feet (2.7 meters) closer each year. Second, the oval orbit turns slowly, by 17.6 degrees per year — some 150,000 times faster than the relativistic drift of Mercury's orbit. Third, because both gravity and speed slow time, the pulsar's clock runs at a varying pace along the oval orbit, shifting its pulses by up to about half a millisecond.
"From these measurements, we determined the pulsar mass and the companion mass," Han explained. "The total mass is the lowest among all known double neutron star systems." The pulsar weighs about 1.3 times as much as the sun, and its companion is just 1.19 solar masses — one of the lowest-mass neutron stars known. Simulations suggest that supernovas can't forge neutron stars much lighter than that.
The stars will merge in about 82 million years. That merger will probably leave behind a heavier neutron star of about 2.26 solar masses, though the remnant could instead collapse into a black hole, the researchers estimate.
Any two of the three effects are enough to calculate both stars' masses. The third then serves as an independent check, because if general relativity is correct, all three must point to the same masses — and they do.
"We found that general relativity is needed to explain the data, and the consistency is about 1%," Han said. The double pulsar test is more precise, but it drew on 16 years of data, compared with about five for the new pair. "Unfortunately, we could not beat this description of gravity," Han added, referring to physicists' hope of finding cracks in Einstein's theory that might reveal new physics.
Next, the team hopes to detect "frame dragging," an effect in which a spinning mass twists space-time around it, making nearby orbits wobble. "In the future, we will monitor this pulsar, probably over decades, to detect the frame dragging induced by the neutron star's spin," Han said.
Measuring the effect would reveal the pulsar's moment of inertia, which depends on how its mass is spread out inside. That would provide "a novel constraint" on how matter behaves at the crushing densities in neutron star cores, Han said — one of the biggest open questions in physics.
'> Lightest known pair of neutron stars proves Einstein right yet again
Finally, the doctors agreed with the initial diagnosis: The pilot was experiencing migraines. The causes of migraine are not fully understood, although genetics and environmental factors may contribute to both the duration and intensity of migraine pain in a given individual.
Indian Air Force (IAF) fighter jets photographed in 2019. The patient's headaches were sometimes so bad that they stopped him from conducting scheduled flights. (Image credit: Abhishek Singh via Getty Images)The treatment: The pilot was given the migraine medicine sumatriptan, to be taken at the first sign of pain, and aspirin, to be taken during headaches. He was allowed to continue flying under restricted conditions, and he had to report to a military neurologist for monthly reviews over the next three months.
Four months later, he was headache-free and had stopped taking medication, according to the report. However, his superior officers needed a detailed medical review before they could restore his unrestricted flight status, as severe migraines can disqualify pilots from flying.
Over three days, doctors conducted in-depth interviews with the pilot, focusing on the first appearance of his symptoms and the circumstances leading up to his headaches. They were puzzled by certain details: His lack of nausea, vomiting and auras, and the fact that he got no relief through sleep. These facts raised questions about the migraine diagnosis.
During the interviews, the pilot recalled that his headaches began around the time that he started using a new type of helmet with a tighter fit. The headaches corresponded with days in which he flew multiple flights and became worse the longer he wore the helmet. Then, around the time he started taking the prescribed medication, he coincidentally received a new allotment of personal flying clothing — including a helmet that was the correct size — for a new plane assignment. His headaches suddenly stopped.
"At that point the officer did not connect the cessation of headaches with the use of the new helmet," the doctors reported. "Reviewing the case in its entirety, the diagnosis of migraine or vascular headache was found to be incorrect; instead the individual was suffering from external compression headache due to an ill fitting helmet."
Compression headaches are caused by tight external pressure on the scalp and forehead, and they typically resolve when the pressure eases.
Doctors instructed the pilot to keep a headache diary and scheduled follow-up visits to confirm their findings. Five months later, his headaches had not returned, as he'd continued using the better-fitting helmet.
What makes the case unique: When the military doctors scoured peer-reviewed studies, they found no reports of similar instances of compression headache "in any of the Air Forces of the world," they wrote in the report.
This case, they added, emphasizes the medical significance of making sure that pilots' flight uniforms — especially their helmets — fit properly.
For more intriguing medical cases, check out our Diagnostic Dilemma archives.
This article is for informational purposes only and is not meant to offer medical advice.
Can you guess the diagnosis in these strange medical cases? Find out with our diagnostic dilemma quiz!
'> A fighter pilot had unexplained headaches for over a year. The cause was hiding in plain sight.