, Genghis Khan's would likely appear near the top of the list — in part to fact-check the gruesome legends surrounding his burial.

He was born in Mongolia around 1162, and supposedly emerged from the womb clutching a clot of blood in his fist. By all rights, the boy — whose original name was Temüjin — should have died young. His father, a nobleman in their tribe, was poisoned by a rival tribe when Temüjin was nine, and greedy schemers within his own clan banished the boy's family to the empty steppes, expecting them to starve. Historical accounts describe Temüjin as overly sensitive, terrified of dogs and prone to crying.

But he grew up fast. Even before adolescence, he'd already been enslaved (he engineered his own escape) and killed his older half brother. As a young man he discovered that soldiering suited him, and he ruthlessly eliminated all potential rivals among other nomadic tribes, until he was crowned Genghis Khan — universal ruler — in 1206. His other nickname was the Disturber of the Universe. His warriors were bold and battle-tested, and when they stopped murdering each other and turned their attention outward, they proved unstoppable.

They favored blitzkrieg tactics, sweeping in on horses and bombarding the enemy with arrows. But they could be surprisingly patient, too, and perfected the art of siege warfare. One notorious siege involved the city of Merv, in what's now Turkmenistan. Merv was the Alexandria of its day: a desert oasis teeming with gardens and libraries, famous for its silks and refreshing melons.

The Mongols couldn't resist it, and when the terrified artists and merchants inside surrendered after just six days of siege, a massacre ensued. "It was a memorable day for shrieking and weeping," lamented one chronicle. After burning Merv for good measure, Genghis Khan ordered his troops to count the corpses. There were 700,000. Yet however crazy it sounds, life under Genghis Khan had its benefits. He allowed the conquered to worship whatever gods they liked, a rare example of religious tolerance. He introduced the idea of diplomatic immunity to facilitate negotiations, and outlawed torture during interrogations. He promoted free trade, and founded history's first international mail system.

Over time, his empire also spread key technologies like the compass, abacus, printing press, and paper currency, as well as key social programs like universal education for children. No one was more ruthless when conquering (ask Merv). But if the vanquished people picked up the pieces and swore fealty afterward, life generally improved under Mongol rule. Genghis Khan's realm stretched from Korea to the Caspian Sea, an area twice the size of the Roman Empire. (Under his successors, it grew to the size of Africa.) And he accomplished all this with an army of just 100,000 warriors — fewer people than some modern stadiums hold.

Historian Jack Weatherford summed up his achievements thus: "[Imagine] if the United States ... had been founded by one of its illiterate slaves, who, by the sheer force of personality, charisma, and determination, liberated America from foreign rule, united the people, created an alphabet, wrote the constitution, established universal religious freedom, invented a new system of warfare, [and] marched an army from Canada to Brazil." Alexander, Julius Caesar, Napoleon — they weren't fit to carry Genghis Khan's saddle. If anyone in history deserved a grand mausoleum, it was him.

Genghis Khan wanted the opposite. Despite all the blood they shed, the Mongols were oddly squeamish about discussing d-e-a-t-h, so beyond the year 1227, contemporary sources say little about how Genghis Khan died. As a result, rumors multiplied. One story claims he died after tumbling off a horse. Others have him struck down by lightning or an arrow to the knee during battle (at age 65, no less). One source swears he was trying to ravish a conquered queen who, anticipating the crime, concealed a blade inside her vagina that sliced lil' Genghis wide open.

Regardless of the truth, his longtime wife Yesui dressed his body in a white robe, wrapped it in white felt with sticks of fragrant sandalwood, and clasped the shroud shut with golden straps. What happened next is impossible to say for certain. But according to lore, Genghis Khan received probably the most outrageous funeral in history.

After his wife bound him in white, a thousand soldiers took off on horseback to bury him atop a mountain. This cortege quickly turned into a rampage. To conceal their destination, the troops reportedly slaughtered every person they encountered on the 40-day journey, often with the cry "Go to the other world to serve our lord!" In some accounts, the soldiers killed every animal, too. Based on other Mongol burials, they likely interred him 20 yards deep, with the body oriented north-south and the head facing east. They probably tossed some treasures in — gilded saddles, gold rings, pearls wrapped in silk — along with slaves, concubines, and horses. (One tale has the soldiers burying a live baby camel with him, either so its bleating would serve as a funeral dirge, or so the grieving mother could lead them back to the site if necessary.)

After filling the grave, Genghis's soldiers either diverted a river to conceal it or trampled the ground with a thousand horses to obliterate all trace. Then they resumed the merry rampage on the return trip, butchering every unlucky hunter or merchant who wandered across their path. To their surprise, the thousand soldiers were themselves slaughtered when they reached home, as a further guarantee of secrecy — and then those slaughterers were also slaughtered, to make doubly sure.

Genghis Khan took privacy seriously. We have no idea how much of that is true. But it hasn't deterred the hunt for the grave. To the contrary: The elaborate concealment has made the pursuit all the more enticing. Four nations — Mongolia, China, Kazakhstan, and Russia — have claimed that Genghis Khan's bones lie within their borders. The strongest claim points to Burkhan Khaldun (God Mountain) in northeast Mongolia. Genghis Khan was born nearby, hunted there regularly, and worshipped the sky god Tengri there. He also once took refuge there while fleeing his enemies, and miraculously escaped. The mountain seemed charmed to him, and he'd mused during his life that it would make an ideal final resting place.

Strengthening the case for Burkhan Khaldun is the fact that later Mongol rulers proclaimed the land around the peak a forbidden zone and stationed a clan of ferocious guards there — the Darkhad, who murdered anyone who dared approach. (In exchange, the Darkhad paid no taxes and avoided compulsory military service.) Incredibly, the Darkhad kept this watch for 700 years, until the founding of the communist Mongolian People's Republic in 1924. The republic was a puppet state of the U.S.S.R., and Soviet leaders had a schizoid attitude toward the Disturber of the Universe. On the one hand, they admired his ruthlessness and gazed longingly at all the territory he'd gobbled up. On the other, they feared his memory would stir up nationalist sentiments in Mongolia and spur a revolt against the hated communists.

To forestall this, the Mongolian government banned the very mention of Genghis Khan's name. And to prevent Burkhan Khaldun from becoming a rallying point, officials fenced off a "highly restricted area" around the peak of 3,900 square miles (twice the size of Delaware), and parked a tank base at the site's entrance. The ban thawed somewhat after Joseph Stalin died in 1953, and one Mongolian official decided to celebrate the Disturber's 800th birthday in 1962 by putting him on a stamp. He overreached. Moscow ordered the man arrested, and he was chopped to bits with an axe. After the republic collapsed in 1992, the restricted area devolved into a nature reserve with some public access. But the land near Burkhan Khaldun remains daunting to explore. It's one of the most desolate places on Earth, with few roads and a population density down there with Greenland's.

Centuries of vegetation growth have choked off many areas, and the clear parts are prone to flash floods. Temperatures can swing from 100 degrees [Fahrenheit, or 38 degrees Celsius] in the summer to 50 below [minus 46 C] in the winter, so cold that even yaks drop dead. None of this has stopped Genghis Khan obsessives from searching out his grave. They've suffered snakebites and frostbite and been left stranded when their vehicles tumbled off cliffs. One man spent 40 years crossing and crisscrossing and re-crisscrossing the slopes and died without finding a thing.

In 2010, a few archaeologists tried a new approach. They posted satellite images of the Burkhan Khaldun region online and recruited volunteers to scour them for bumps, depressions, and other features that might indicate graves. Ten thousand people spent approximately 30,000 hours (3.4 collective years) poring over 2,300 square miles [5,950 square kilometers]. They flagged over a hundred spots worth checking out. While several proved inaccessible due to challenging terrain, 55 legitimate archaeological sites turned up among the rest, including megaliths, Bronze Age burial mounds, and an ancient city.

But there was zero trace of Genghis Khan. One archaeologist lamented that it was like looking for a needle in a haystack, except you don't know what the needle looks like. Call it Genghis Khan's final victory. The diverted river and trampling horses and the slaughter of all potential witnesses have succeeded in hiding him for most of a millennium now. His victims lay scattered across Eurasia, their skeletons long since ground to dust. But the bones of history's greatest warrior remain at peace.

Excerpted from The Museum of Lost Things by Sam Kean, published by National Geographic Partners, LLC. Copyright © 2026. All rights reserved.

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'> Why the tomb of the 'Disturber of the Universe' remains hidden after 800 years

Officially full at 12:49 p.m. EDT on Saturday, the full moon will be best seen rising in the eastern sky later that day, at the time of moonrise where you are. It will appear in the constellation Pisces.

This month's full moon earns the Harvest Moon nickname because it's the full moon closest to the September equinox, which fell on Tuesday (Sept. 22). This year, it coincides with the Mid-Autumn Festival — also called the Moon Festival — which is held in Chinese and Vietnamese communities on the day of the Harvest Moon, according to Timeanddate.com. However, the Harvest Moon's significance goes beyond traditional nicknames, because the moon behaves a bit differently around this point in the calendar.

Typically, moonrise occurs roughly 50 minutes later from one day to the next. Around the Northern Hemisphere's autumnal equinox, however, the moon's path meets the eastern horizon at a relatively shallow angle. That geometry reduces the day-to-day shift in moonrise times, resulting in a string of evenings with bright moonlight arriving soon after the sun goes down. Before electric lighting and modern farm machinery, those brighter early evenings provided useful extra illumination during the autumn harvest.

That's not the case anymore, but skywatchers nevertheless have more than one night when the full lunar disk emerges above the eastern horizon into a sky still filled with twilight. Across North America, the moon will rise only about 25 minutes later on Sunday, Sept. 27 than on the previous evening.

Saturn will add another reason to watch. The ringed planet will appear close to the Harvest Moon, rising just beneath it as seen from North America and is easily bright enough to see without a telescope. However, a backyard telescope or stargazing binoculars can give you an even crisper view of both Saturn and the moon. To get the best chance of catching the moon as it appears, find an observing spot with an unobstructed view to the eastern horizon.

The next full moon, known as the Hunter's Moon, will occur on Friday, Oct. 25 or Saturday, Oct. 26, depending on your time zone. It will also be a supermoon, making it appear larger and brighter than average.

How much do you know about the moon? Test your lunar smarts with our moon quiz!

'> Harvest Moon 2026: See the first full moon of autumn rise alongside Saturn tonight 36 million people worldwide.

Clinically, bipolar disorder is defined as a mood disorder characterized by specific, lasting changes to a person's mood and energy levels. Depending on the type of bipolar disorder, individuals can experience manic, hypomanic and depressive episodes — either individually, or in sequence.

However, "experiencing mania itself is sufficient to have a diagnosis of bipolar [disorder]," said Dr. David Cousins, a clinical senior lecturer and honorary consultant psychiatrist at Newcastle University in the U.K. "It's probably easiest to think of that as the opposite of depression — people become elevated in mood, extremely energized, driven, motivated, and engage in hedonistic behavior with lots of risk taking," he said. "It's a highly detrimental, highly damaging, highly disruptive state."

Treating an illness that operates at such extremes is a difficult balance to strike, with any intervention to treat one emotional state needing to factor in how it could impact the other. "For example, if you gave somebody antidepressants without an antimanic drug, you might either trigger mania or destabilize the illness," Cousins explained.

A combination of antidepressants, antipsychotics, and mood-stabilizing anticonvulsants are often prescribed in combination to juggle these highly variable symptoms. "There are really very few medications that have an overall effect against both poles," Strawbridge said. Once stabilized, the challenge then becomes preventing relapse back into this destructive cycle.

Lithium, by contrast, does not suffer from these limitations, Strawbridge added.

"It's often considered the gold standard for bipolar disorder; it's helpful for the depression and for the mania, but its main benefit overall is in preventing relapse, so stopping either of those two types of episodes from coming back."

Psychiatrists usually prescribe lithium as either lithium carbonate tablets or a lithium citrate liquid, both of which dissociate inside the body into lithium ions and their corresponding counterion (either carbonate or citrate). This simple active form is part of what gives lithium its powerful, broad-ranging mood-stabilizing effect, Strawbridge said.

"Because lithium is quite a simple ion, it's able to disguise itself as sodium, and that means it can slip inside of brain cells, whereas most medications act on the surface of cells," she explained.

Lithium's simple form enables it to spread throughout the brain and rest of the body. Once inside, it interacts with many cellular processes, but doctors still don't really understand the underlying mechanism behind its beneficial effects.

"We know that the monoamine system and the neurotransmitters in the brain that are involved in reward emotions and cognition are disrupted," Victoria Wing, a clinical lecturer at the National Institute for Health and Care Research at Newcastle University and CNTW NHS Foundation Trust, told Live Science. Included in this disruption is the regulation of crucial mood molecules, such as dopamine and serotonin, which may be underactive or overactive depending on the nature of the bipolar episode.

The same small lithium ion also blocks an enzyme called glycogen synthase kinase 3. This enzyme has wide-ranging downstream effects, such as controlling gene activity, regulating the body's circadian rhythms and managing inflammation and cell survival.

"Lithium can also help with autophagy, which is the clearance of debris and toxins in cells, and it has antioxidant effects and boosts mitochondrial function, which are important for cell energy processes," Wing said.

However, despite its manifold therapeutic benefits, lithium does have some drawbacks. While around one-third of people experience profound benefits from the drug, another close third only experience intermediate effects, and the final rough third don't respond at all.

This means it's vital to identify which patients respond well to the drug as early as possible, especially because the cyclic nature of the condition means it can take years to ascertain whether lithium is effective in preventing relapses in the long-term, said Cousins. The drug also has a narrow therapeutic window, which means it has a small margin of safety between doses that are high enough to be effective and those that are toxic to the kidneys and thyroid. Some patients who undergo lithium treatment also report having to urinate more frequently or experiencing slight tremors.

As with any medication, some side effects are unavoidable. The alternatives to lithium also carry their own risks. But if carefully and correctly managed, lithium medications can have a transformative impact for patients.

"I've met a lot of patients through patient involvement groups that have told me how effective and lifesaving lithium has been for them," Wing said. "We know it works, but can we fine-tune the use even better so more people can benefit from it?"

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

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'> Why does lithium work against bipolar disorder?

PRIMA's objective is to use a 5.9-foot [1.8 meters] telescope to examine the cosmos in the far-infrared, in a different set of wavelengths than the more famous JWST, which launched in 2021. (Other telescopes, such as Hubble and the newly launched Nancy Grace Roman Space Telescope, can also see some infrared wavelengths, but JWST was specifically designed to detect near- and mid-infrared light.) PRIMA's mission focus will be to uncover more information about exoplanet origins, galaxy growth and black hole evolution.

"The key science questions that PRIMA aims to address in relation to planet formation are to quantify the role of water in driving planet formation, [and to] determine the total gas masses and carbon and oxygen abundances in disks to reveal where exoplanets form," Meredith MacGregor, an associate professor of physics and astronomy at Johns Hopkins University who studies how planetary systems form, told Live Science in an email.

"We can't actually address these science questions with JWST," MacGregor added, "because the spectral lines that are required are only in the far-infrared — longer wavelengths than JWST is sensitive to."

The University of Maryland (UMD) and Caltech, which helped develop the mission, each issued statements about the upcoming work.

"I'm most excited about the things I don't yet know," Alberto Bolatto, an observational astronomer at UMD and a co-investigator who leads galaxy evolution research for PRIMA, said in a statement. "I am elated to be part of the future of astronomy — to produce an instrument that is going to be an enormous tool for the astronomy community to move humanity's knowledge forward."

"I am particularly excited about how PRIMA will help us discover and understand the role of powerful molecular outflows in galaxies over cosmic time, and how they shape star formation and the growth of supermassive black holes in the centers of galaxies," Lee Armus, a staff scientist at Caltech and the PRIMA co-investigator and science operations lead, said in a separate statement.

Dawn of the Probe Explorers

PRIMA has a project cost cap of $1.2 billion, excluding launch and other nonproject expenses; for comparison, JWST cost $10 billion at launch in 2021, not accounting for inflation or launch expenses.

PRIMA is also the first in a new class of spacecraft that NASA is calling Probe Explorers, which are meant to sit somewhere in between flagship, JWST-style missions and smaller agency efforts. Probe Explorers are a part of the decades-old Explorers Program that began with the Explorer 1 launch in 1958 and followed with more than 100 missions. Explorers perform "a wide variety of research and scientific exploration programs for Earth studies, space weather, the solar system, and the universe," according to the agency.

The Probe Explorers were implemented after a recommendation from astrophysicists through the 2020 Decadal Survey, which is a consensus report issued by the National Academies of Sciences, Engineering, and Medicine on behalf of the community. NASA funded two concepts at $5 million apiece in 2024 and considered both PRIMA and the Advanced X-ray Imaging Satellite before announcing the decision to proceed with PRIMA this week.

"NASA selected PRIMA for development after detailed evaluation of concept studies for Probe Explorer missions, based on their scientific merit in alignment with the Decadal Survey's recommendations, feasibility of their development plans on cost and schedule, and use of technologies that could support the development of future large missions," the agency stated Wednesday (Sept. 23).

Should the mission fly as hoped, NASA's Jet Propulsion Laboratory will manage PRIMA, with contributions from numerous other NASA centers and international agencies.

'> NASA teases new PRIMA telescope that could see what even the James Webb telescope can't

Unlike current earbuds, devices with the new chip will be able to host apps right on the memory of the devices themselves, without relying on a continuous smartphone connection, as well as sync with cloud-based services like ChatGPT when connected to Wi-Fi. In practice, the chip will enable users to make vocal queries and requests, with an AI model taking actions such as setting up entries in an online calendar or making online purchases. Unlike existing devices that can perform similar functions, this would be possible without a smartphone connection.

Beyond earbuds, company representatives want to integrate the chip into other "hearables," such as over-ear headphones, open-ear audio devices, audio glasses, camera buds (headphones that use tiny built-in cameras) and hearing devices, as well as "future personal AI wearables," like pendants or clips.

What features will the chip enable, and how does it work?

For users who wish to connect hearables to a smartphone or computer (to interact with a visual user interface, for example), the new chip uses a specialized component within the platform to establish connections over micropower Wi-Fi channels alongside Bluetooth. This technology harnesses architectural improvements at the chip level to consume much less power than standard Wi-Fi connections — but at the expense of higher latency and lower peak speeds. For audio devices, however, using Wi-Fi rather than Bluetooth generally improves playback quality, given that Bluetooth compresses data during transmission, Qualcomm representatives said.

Adaptive and selective active noise cancellation also means users can filter out audio on command. For example, it allows listeners to hear key sounds, such as emergency sirens, while walking through a city or highlight people's voices during a conversation, while blocking out everything else. This noise cancellation is achieved through standard machine learning algorithms, rather than transformer-based large language models that power AI systems like ChatGPT.

Devices could also allow lossless audio streaming — a high-quality audio standard that's usually available only if you subscribe to premium streaming services, like Spotify or Tidal — thanks to another built-in subsystem.

Qualcomm representatives also highlighted the chip's "always-on intelligence," in which an on-device eNPU AI accelerator component powers virtual assistants, transcription and translation, as well as the building of "contextual awareness." With contextual awareness, the system would constantly monitor the user's environment to harvest data to add to a personal profile, which representatives say helps it answer future queries.

Although the system is audio-centric, it's also built to interface with hardware that includes sensors and cameras — like earbuds with built-in lenses that passively capture footage of a wearer as they go about their daily lives. This forms part of the data harvesting to build contextual awareness for the agentic AI systems people can access. Qualcomm representatives attempted to assuage privacy concerns by saying camera lenses on future earbuds would be low resolution and wouldn't identify specific individuals due to an AI mask that automatically obfuscates them.

There's no information yet about the likely impact of these features on battery life compared with conventional non-AI devices. But Qualcomm representatives noted that device makers will no longer need to choose between audio quality, AI features and battery life. That said, Andrew Laister, staff product manager at Qualcomm, added in a media Q&A session that there's likely to be an impact on how a user experiences battery drain. That's because, unlike conventional earbuds that are used sporadically for calls and music playback, these new devices are designed to be used continuously.

How does Qualcomm's new AI chip compare with similar technologies?

AI-enabled headphones already exist in some capacity. For example, manufacturer Viaim launched its Rise and RecDot devices this year. These are designed to record, transcribe, translate and summarize conversations, although details on the chips powering them are not publicly available. Apple's AirPods, for example, let users tap into the Siri AI system, but they require a continuous iPhone connection to perform complex tasks.

Devising smart audio features and getting them to work in real devices have also been at the heart of several recent research projects. For example, in 2024, University of Washington scientists embedded a computing system into off-the-shelf earbuds to zero in on individuals speaking in noisy environments while blocking all background noise.

The previous year, the research team put a deep learning system into headphones so wearers could use voice commands to engage with a selective active noise cancellation system, choosing which sounds to hear and which ones to block out.

Other companies have explored building new kinds of digital audio platforms for headphones. Three years ago, xMEMS unveiled Cypress, an audio chip that generates ultrasonic sound using the "piezoelectric effect," in which a material moves when a current is applied to it. Although the chip entered "mass-production readiness" in September 2025, consumer devices fitted with the platform have yet to be announced.

Apple also may be working on a similar technology. This could manifest as AirPods with built-in cameras that will perform similar data harvesting as users go about their day-to-day lives, according to Bloomberg Managing Editor Mark Gurman.

Qualcomm's new chip is a spiritual successor to the 3-year-old Snapdragon S7 Gen 1 system, which featured in devices such as the Xiaomi Buds 5 Pro series. The previous chip also used AI for conventional active noise cancellation, audio customization and lossless audio streaming while connecting to devices via micropower Wi-Fi.

However, the new chip has twice the AI power, completing 128 billion operations per second, compared with the previous one's 64 billion operations per second. It also uses 40% less power and is 30% smaller.

A crucial aspect of the new system is its capacity to store apps on the device itself in the chip's onboard memory. Because the device will have its own IP address, it can communicate with servers using the https protocol, without needing to go through another phone or computer.

Laister told journalists in the Q&A session that the company is currently scoping out whether the device could run two apps in RAM (short-term memory) at once — an AI agent and an audio streaming platform, for example — while keeping the rest in flash memory (long-term storage). He added they had to overcome a communication hurdle with micropower Wi-Fi foron the launch of the previous chip (specifically, that its power consumption is on a par with Bluetooth's). Now, he said the communication hurdle is actually being able to run apps on the device.

"It's like the first smartphone moment with the Play Store, but in this sense, that app store for your earbuds is currently owned by the device maker," he added. "They will be the guys that will choose which apps they will pre-bundle, and then we'll go from there."

No details were available on when the system is likely to be found in devices, but representatives said Qualcomm is working with other companies, including HP and Bose, to explore headphones and speakers that feature the chipset.

Live Science was invited to attend Snapdragon Summit 2026 courtesy of Qualcomm, with the company covering travel and accommodation.

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'> New kind of AI audio chip transforms earbuds into always-on 'intelligent' devices that run without a smartphone. How does it work?