Earth is the only planet we know of with buoyant, silica-rich continents. But, despite decades of research, geologists still don't agree on how they formed. "The continents started appearing around about four billion years ago—that's the oldest continental rock we know about,” said Tim Johnson, a geologist at Curtin University in Perth, Australia. “The Earth is four and a half billion years old, so why they started appearing then is unknown, as is the mechanism to make that continental crust."

Johnson and his colleagues are now arguing that the formation of continents on Earth was caused largely by an intense, sustained barrage of asteroid impacts that kept the early crust hot and thin enough to make buoyant continents possible. In short, the lands we live on are here because of ancient bombardment from space.

Plates and plumes

The problem with studying the formation of continents is that the geological evidence of this process is almost gone. The oldest known continental-type rocks crystallized around 4.03 billion years ago, right at the end of the Hadean eon (the earliest era in Earth’s history, spanning the first 500 million years of its existence). Rare basaltic rocks date back about 4.2 billion years, and a handful of the oldest zircon crystals push the record back to 4.4 billion years. Beyond that, there's hardly anything else. So, scientists looking into the origin of continents had to rely largely on educated guesses. “There are huge debates about what was going on in the early Earth, because the data is so scarce,” Johnson said.

One dominant idea holds that plate tectonics, much like today's, was already running in the Hadean, with continental crust forming above subduction zones—areas where tectonic plates collide. The other claims that early Earth was too hot for rigid plates, and that crust instead formed above mantle plumes rising from deep within the planet, a phenomenon comparable, Johnson said, to the wax blobs rising inside a lava lamp.

The issue with both these ideas, though, was that Earth, based on most models, appeared too cold for all this to happen. “People have tried to understand Earth's heat budget through time, and nobody could make it fit,” Johnson said. “Nobody could make it fit because we did not consider the energy coming from outside of Earth.” This energy, he argues, came from asteroid and meteorite impacts that were far more frequent back when the solar system was young. Adding these impacts to the early Earth’s heat budget, though, proved rather challenging because Earth has a peculiar way of healing its scars.

The moon shot

The reason we don’t really know what was happening on Earth four billion years ago is that plate tectonics effectively recycles the surface of the planet back into the mantle. “One place where we do know what was going on back then is the Moon,” Johnson said. “We have sent people there. We have collected sample from there. We have immense amounts of high-quality data from the Moon." Because the Moon does not have plate tectonics, its crust is a single, solid, continuous shell. And this shell, Johnson’s team noted, is peppered with impact craters.

Calibrated against dated lunar samples, crater counts on the Moon let Johnson’s team estimate how frequently large bodies were hitting our closest celestial neighbor shortly after the Earth had formed. “Scaling that flux up to Earth’s larger size and stronger gravity makes it clear the planet must have been hit by thousands of impactors that were greater than 10 kilometers in diameter,” Johnson said. When his team determined the most probable frequency of impacts and the size of impactors, they could calculate how much energy this immense bombardment delivered to Earth and, consequently, how much heat it produced.

It turned out it was a lot of heat.

Most prior modeling of early Earth's heat budget focused on internal sources like heat left over from accretion and core formation plus the ongoing decay of radioactive isotopes—we thought these were absolutely dominant. Johnson’s space bombardment model showed they were not.

Bringing the heat

The team focused on modeling how the kinetic energy of each impact would ultimately end up as heat. The physics, Johnson said, is straightforward even if the details are complex. "It really is as simple as converting the size and the velocity of the impactor into energy," he explains. When a large body hits, some of the impact energy goes into vaporizing or melting rock right at the impact site. But, especially when an impactor is big, most of it propagates into the mantle below. "This energy basically heats up the entire upper mantle," Johnson said.

This heat drives more melting and more basaltic volcanism, a process that plays out not just in the minutes-to-hours timescale of the actual collision, but in tens or even hundreds of millions of years afterward. When Johnson and his colleagues added up these contributions, impact heating exceeded radiogenic and core heat for most of the Hadean by roughly an order of magnitude.

Feeding this reworked heat budget into geodynamic simulations led the team to the conclusion that the Earth’s crust in the Hadean was thin and largely molten underneath. The models suggest it was less than 5 kilometers thick, with widespread partial melting starting just 2 to 3 kilometers below the surface. At around 5 kilometers depth, melt fractions exceeded 30 percent by volume—well past the point where rock can hold together as a coherent slab.

The key takeaway was that plate tectonics could not work in such conditions. "Subduction and plate tectonics require that your lithosphere is rigid and it can jostle around and subduct,” Johnson said. “That's just not possible if our calculations are anywhere close to the mark.”

The simulations that captured the localized effects of individual large impacts also produced wholesale recycling of crust back into the mantle, with material dripping down to depths of at least 600 kilometers. Johnson thinks this recycling explains why so little Hadean crust survived to the present. It also explains, he argues, the near-total absence of shock-deformed Hadean zircons in the geological record. The researchers suggest that with so much melt present at shallow depths, it would have absorbed and scattered shock waves before they left lasting deformation in surviving crystals.

A turning point

The impact flux didn't stay high forever; it declined more or less exponentially. Between 3.9 and 3.5 billion years ago, it had dropped enough that internal heat sources took over as the dominant influence on the crust. As impact heating faded, the upper mantle cooled, and the once-thin basaltic crust thickened.

The team's modeling suggests crustal thickness reached around 30 kilometers by the early Archean, the era that came after the Hadean. This thicker, cooler, more rigid crust was also finally able to support plate tectonics, and it's around this same time that the first continental rocks show up in the geological record. "As soon as you can create thick crust and you can create a mantle lithosphere underneath, you can start building continents," Johnson said.

The team admits much of the argument rests on physics-based modeling rather than rock samples. In the absence of geological evidence, though, Johnson thinks reliance on modeling is justified. “We need to start taking seriously the outputs of these models rather than just say, well, we can't find any rocks, so let's give up," he said. But ancient rocks, as hard to find as they are, may also pop up in near future—the Earth is extremely good at covering the tracks of its history, but it’s not perfect.

“In Nuvvuagittuq Greenstone Belt in Canada, a team of North American researchers has recently dated a dark, mafic rock as 4.2 billion years old,” Johnson said. “I also know another group has found a rock which is possibly even older. Hopefully you will be able to read about it in the next couple of months.”

Science, 2026.  DOI: 10.1126/science.aeb5402

Read full article

Comments

The last time America celebrated a big anniversary, I was all of three years old. Even so, I retain a few fuzzy memories from a sunny summer afternoon in small-town Michigan: climbing on a cannon in front of the courthouse, watching a parade, and seeing my dad, a veteran and Centreville city councilman, giving a short talk about democracy.

Only later would I realize the significance of the date: July 4th, 1976, America’s bicentennial.

America was imperfect and inconsistent in its approaches to "freedom," but the country had done some big, difficult things in recent decades. We had led the charge to roll back the tide of fascism and Holocaust during World War II. We had begun to confront internal demons through the nonviolent activism of the civil rights movement. And, critically for my own life trajectory, we had landed on the Moon.

The '70s were hardly a simple or heroic time, but I was too young to experience the turbulence of the era. My dad fought in Vietnam but returned before I was born, and I have no recollection of Watergate or waiting in lines for gasoline during the 1970s energy crisis.

Instead, I came of age in the 1980s, watching the Berlin Wall fall and American pop dominate the global charts. When I entered the job market during the 1990s, the economy was booming. Our investments in basic research and universities made this country the preeminent scientific and economic power in the world. By the start of the new millennium, with China only beginning its rise, there stood just a single superpower in the world. Despite our many problems and failures, America remained something one could still celebrate in an imperfect world.

And then—what?

It remains difficult to pinpoint the moment in my life when it felt like my country started to lose the plot. Oh, there were signs, like the September 11 attacks and the botched response that drew us into interminable entanglements in Afghanistan and Iraq without "fixing" either country. The financial collapse in 2008 accelerated wealth inequality. Increasingly online, Americans started populating echo chambers and imbibing conspiracies, and distrust of the media grew. No one could agree on a common set of facts anymore, let alone debate them in good faith. More kids wanted to become social media influencers than astronauts.

Anger, isolation, and paranoia rose. Big things weren't getting done, couldn't get done. With the rise of smartphones, life shifted even further toward screens to mediate the world. The forces of ignorance and grift even managed to turn parts of Americans against vaccines, arguably the single most life-saving medical invention in human history.

All of this played out against an increasingly poisonous political environment. When Donald Trump was first elected a decade ago, many Americans were struggling and felt unserved by the existing political class. Trump campaigned on addressing those frustrations, promising disruption instead of the status quo. Americans chose disruption, and they got it. They also got hatred, contempt, bullying, misogyny, narcissism, corruption, lies, and a palpable love for dictators—and what were these but symptoms of advanced political disease?

The numbers show that Americans have been unhappy with the direction of the country—though for different reasons—for twenty years. And in 2026, Americans' optimism about their own futures has fallen to a record low, lower even than during the pandemic, when people at least still believed tomorrow would be better.

For someone who has watched the last quarter of a century unfold in real time, all this can feel a little hopeless. And as a father of two daughters who recently became young adults, I worry about the world we're leaving to them.

Because we have real problems. The planet is warming. Generation Z is coming into a workforce with uncertain job prospects and futures darkened by artificial intelligence. Billionaires increasingly run the show—and often not in society's best interests. Goodness knows when younger people will be able to buy a home, once considered the bedrock of achieving the American dream. And we've thrown so many addictive habits at them, from corrosive social media to pervasive online gambling, how can we expect them to thrive?

Finding some hope

It would be easy to wallow in this mess—to doomscroll as the world washes away.

But on this anniversary of the United States of America, I believe we are not without hope. It may feel like America has been careening along the highway of enshittification since the turn of the century, but the thing about driving on highways is that you can always take an off-ramp. The truly remarkable thing about this country is its ingenious ability—through elections, immigration, freedom of speech, and economic mobility—to constantly remake itself.

We need to become makers once again, working against the rage, the despair, the grifting, and the misinformation wherever we find them. And we can. Based simply on what I've seen as a journalist over the last quarter century, reasons for hope remain. It can be useful once in while to gather these reasons about us as armor against despair.

About a decade ago, when I left the Houston Chronicle newspaper to write about space full-time for Ars Technica, I also started a website focused on local weather. Our purpose was clear: In an era of sensationalized storm coverage, Space City Weather would provide no-hype information about weather impacting the lives of people in Houston. We stuck to that, and when giving public talks, I often joke, "Boring is our brand."

But in a world awash in clickbait and shouting, the quiet work we have done with Space City Weather still resonated with people. When storms threaten the community, it turns to us—because it trusts us. For many Americans, there remains a hunger for credible, evidence-backed news and information. Of course, if you're reading Ars Technica, you share such a hunger already. But you are not alone.

I spend most of my days writing about space, and I've met so many good people in this industry working to extend humanity's reach to the Moon, to Mars, and to worlds beyond. Courageous and ingenious people build satellites to spy deforestation on Earth, to gather sunlight for energy rather than burning fossil fuels, to connect people around the world, and to secure resources from asteroids and other worlds so we need not strip-mine our own planet. Not all of this will succeed, and not all of these actors are heroes, of course. But if you want to find faith that humanity can still build toward a brighter future, you could do worse than spend a little time on the space beat.

More generally, much of my life has been spent writing about science. I revere the people who gather insights about our universe and attempt to tease out new secrets from nature. It has been a dark time for science, with the White House attempting to slash science funding across federal agencies, undermining "woke" research, and setting ridiculous health policies over vaccines. But even here, where the damage is being done gleefully and wantonly, the US Congress has stood up to these funding cuts in a bipartisan manner. For most Americans, knowledge is not yet the enemy.

Progress does continue, even among the retrograde orbit of our political life. In recent decades, we have seen great advances against cancers like childhood leukemia and metastatic melanoma, and the next 10 to 20 years should bring additional progress with cancer vaccines. As our population ages, there will be a greater focus on advancing aging science. We will continue to see wins with genetic diseases. The story is similar in physics, astronomy, chemistry, and the other sciences.

When I first started writing about science in the mid-1990s, consider how difficult it was for scientists to collaborate using the time-tested tools of books, printed journal articles, and telephones. Today, researchers can access almost every bit of knowledge about a specialized topic, instantly; work globally with hundreds of scientists; sequence genomes cheaply; and run models on powerful supercomputers. And science is now global. No single government or religion can halt its progress. When America showed the world during the latter half of the 20th century that basic research begat economic development in a big way, the world took note.

Finally, reality itself has a way of fighting back against lies and propaganda. Yes, it takes far longer than one would like. But in the end, badly built rockets explode. False medical claims don't cure. Companies with corrupt accounting—early in my career, I covered Enron's bankruptcy case in New York City—eventually fail. More recently, we have seen commercial satellite imagery and communications provide incontestable truths about Russian activities on the ground in Ukraine, undermining attempts at propaganda. As Shakespeare wrote, "Truth will out."

Power surge

There are so many reasons to be unhappy about the state of America, the world, and humanity as we come to the nation's 250th birthday. But America has been resilient. And the beauty of this country is that every person has the power—small in isolation but much greater in the aggregate—to make change. That power is not wholly spent, nor wholly eclipsed, by anti-democratic forces. Because I am unlikely to greet America when it turns 300 years old, the best time for me to exercise that power is today. I hope you'll join me.

Read full article

Comments

Tina Peters’s ostentatious lack of remorse hasn’t stopped Polis from tripling down in the handjob he personally delivered to Donald Trump:

Gov. Jared Polis of Colorado on Wednesday fired two members of his clemency board after they spoke out against his decision to commute the prison sentence of the election denier Tina Peters.

The board members, Hannah Seigel Proff and Azra Taslimi, had objected to Mr. Polis’s decision in May to release Ms. Peters from prison after pressure from President Trump.

After the commutation, Ms. Proff and Ms. Taslimi revealed that the board — appointed by Mr. Polis — had twice voted unanimously to reject Ms. Peters’s application for a shortened sentence. Mr. Polis, a Democrat, has the final decision, and overruled the board.

The board normally operates in secret, and does not disclose the pardon and commutation recommendations it makes to the governor. Ms. Proff and Ms. Taslimi said they had been compelled to pierce that veil of secrecy in Ms. Peters’s case.

On Wednesday, they said they had paid the price. They received a letter from the governor saying they were being dismissed for violating the board’s confidentiality standards.

I admire their courage in calling out Polis’s grotesque betrayal of American democracy.

The post What the fuck is wrong with Jared Polis? appeared first on Lawyers, Guns & Money.

Some gamers are concerned about the future of game ownership after Sony's announcement today that it won’t produce physical discs for PlayStation games as of January 2028. On that date, “new games will be available on PlayStation Store and at retailers in digital formats only,” Sony said in a blog post.

Ditching discs is “a natural direction” for Sony “to adapt to consumer trends as the general preference for digital media significantly outpaces physical discs," the post said.

During Sony’s fiscal year ending on March 31, 2026, digital downloads accounted for 78 percent of full-game unit purchases, up from 76 percent in fiscal 2024.

“We’ll continue to prioritize our resources to drive innovation in how players can access games and provide choices as to where players prefer to purchase new games, whether that’s at retailers or PlayStation Store,” the blog said.

No companies other than Sony subsidiary Sony Digital Audio Disc Corporation make PlayStation discs, so today’s announcement signals the end of physical copies of PlayStation games and marks Sony’s evolution toward a licensing-only sales model.

You don’t own digital copies

Digital copies of games can make it easier to quickly acquire and play games, receive updates, own many games without needing much physical space, and can help reduce waste. The gaming industry has already mostly moved to this model.

However, buying a digital download is not the same as owning a game. Per PlayStation’s terms of service:

When you order or purchase a product from PlayStation Store, you buy a personal license to use that product for private, non-commercial use. That license is not transferable unless your local applicable laws say it must be. This means you can use a product in the ways described in the license, but do not own the product.

Gaming companies rarely delete previously purchased games from customers’ libraries, but it is possible. In 2013, Valve pulled copies of Order of War: Challenger from customers’ libraries after the game's servers shut down, rendering those copies useless. It would be shocking and unpopular for Sony to remove purchased games from gamers’ digital libraries, but considering that you “do not own the product,” as Sony puts it, the risk remains.

Furthering this concern, Sony also announced today that it will close the PlayStation Store on PlayStation 3 and PS Vita, with the US losing access in July 2027. Although the number of gamers relying on those stores is declining, it remains notable that Sony shied from committing to making previously purchased PlayStation 3 and PS Vita games downloadable for customers’ lifetime.

“To ease the transition, players will still be able to download previously purchased content after the closing date for the foreseeable future,” Sony said.

Both blog posts have comments decrying Sony’s announcements and their implications for ownership and long-term access to PlayStation games.

One user going by Mosquito53, for example, commented:

Another disappointing decision made in the same day. No matter how many users still use these stores, they should remain open. So much content released digital-only, even on these platforms, these games will be lost to time.

Imagine what will happen in the future when this same decision is made for PS4 or PS5 or even the eventual PS6, which now looks to be all digital with the announcement of no more physical disc production.

We will own nothing, it’s truly sad.

Sony has repeatedly reminded PlayStation customers that digital libraries can be temporary. In September, users in the United Kingdom will lose access to previously purchased titles from movie and show production and distribution company StudioCanal. Sony previously pulled StudioCanal content from customers’ PlayStation libraries in Germany and Australia. And in 2024, Sony deleted customers’ Funimation digital libraries despite Funimation previously claiming that customers would be able to access these digital copies “forever but” with “some restrictions.”

Sony has also shown a wavering commitment to its digital stores. In 2021, it stopped selling movie and show rentals/purchases. Leaving the door ajar for customers to potentially lose access to digital games they bought for PlayStation 3 or PS Vita doesn’t boost confidence around the digital-only future.

Further, the removal of storefronts could mean beloved games released only digitally become virtually impossible to find. We’ve seen this happen with Nintendo 3DS and Wii U games. After those digital storefronts closed in 2023, the number of Game Boy games released during Game Boy’s lifetime that were still available dropped from 155 out of 1,873 to 25, according to a 2023 report from the Video Game History Foundation.

“This is why physical media matters,” a user named Radgatt commented on Sony’s PS3 and PS Vita announcement. “More and more proof that you’re just buying a license that can be taken away whenever companies feel like it.

Read full article

Comments

Sony recently informed its PlayStation customers in the United Kingdom that they will no longer be able to watch previously purchased movies and shows from production and distribution company StudioCanal. As of September 1, affected customers will no longer be able to stream 551 titles from the PlayStation Store.

In a legal notice first spotted by gaming news outlet PlayStation LifeStyle, Sony said that affected customers will lose the ability to stream titles including Outrage: Way of the Yakuza, Paddington, Paddington 2, Pan’s Labyrinth, Rambo 3, Terminator 2: Judgment Day, and The Boy in the Striped Pajamas “due to our content licensing agreements.” As of September, Sony will remove any affected titles that UK users bought from their PlayStation library, per the notice.

It’s possible that Sony may still make a deal with StudioCanal by September 1, or even after, that would allow users to keep watching the content they bought. This happened in 2023, when Sony said it would have to pull 1,318 seasons of Discovery shows from customers’ libraries. A few weeks after its announcement, Sony said that it would not pull the content because it had updated its licensing arrangements with Discovery.

Still, affected customers shouldn’t keep their hopes too high. Sony already pulled 314 StudioCanal titles from libraries in Germany and Austria in 2022. More recently, Sony deleted people’s Funimation digital libraries after it decided to merge the anime streaming service with Crunchyroll. Sony has also been scaling down its digital store and stopped selling movie and show rentals and purchases in August 2021. Even if StudioCanal were willing to make a deal with Sony, it’s feasible that Sony has less interest in retaining digital titles than before.

Regardless, the incident is a reminder that we don’t own the stuff we purchase digitally . Instead, digital rentals and purchases are merely long-term licenses that are only valid for as long as the streaming service has the right to distribute said content. Often, that’s a finite amount of time.

Still, Sony's announcement has frustrated some, including those who believe Sony should offer refunds or who think digital stores should stop using terms like "purchase" for long-term rentals. 

Read full article

Comments

Federal authorities are offering a reward of up to $10 million for information leading to the identification or location of a Russian state cyber group that has compromised thousands of Signal and WhatsApp accounts belonging to investigative reporters and US government employees.

The operation has been active since at least March, when the FBI published an advisory warning of ongoing phishing campaigns targeting high-value targets by attackers associated with Russian intelligence services. Messages masquerading as automated support communications ask that users click a link or provide verification codes or account passcodes. In the event the user complies, they unknowingly link the attacker's device to their account or have their account completely taken over and are locked out.

Thousands of accounts already compromised

With that, the attackers can read any new messages sent to the compromised account. A safety feature built into Signal, however, prevents the attackers from reading any previous conversations. The messages are sent to “individuals of high intelligence value, such as current and former US government officials, military personnel, political figures, and journalists.”

Last week, the FBI published an update that said the campaign had evolved. In addition to trying to post as support bots trying to trick recipients into linking their account to an attacker device, the messages also urge users to create a backup of all previous communications following the directions here. A follow-up message then instructs the targets to send the long passcode that’s used to encrypt backups stored on Signal servers. With that, the attackers have access to past Signal conversations. The update said two Russian government groups responsible were tracked as UNC5792 and UNC4221.

One message has text similar to this:

Signal is here

Recently, attempts to hack users of our messenger with the connection of third-party devices to the account have become more frequent.

An investigation conducted jointly with the US government and European partners revealed that the attacks on accounts were carried out by hackers from Iran and post-Soviet countries.

In this regard, Signal updates Terms of Service & Privacy Policy, and introduces Mandatory Two-factor Verification for users.

Not to lose your messages and media, set up your Signal Backup (Settings -> Backups -> Enable backups -> View recovery key -> Copy to clipboard -> Next -> Enter the recovery key -> Next -> Continue -> Choose your backup plan).

Click the "Accept" button in the pop-up and stay tuned for security updates on our messenger.

Stay safe and thank you for using the most secure messenger with end-to-end encryption.

If you have any questions, send /help

Other text looks like this:

Action Required: Data Recovery Needed

Your Signal Account data (messages and media) is at risk of permanent loss due to a sync issue.

To avoid losing your messages and media:

Go to Settings -> Backups -> Configure -> Enable Backups -> View Recovery Key.

Copy the recovery key to your clipboard.

Paste the key into this chat.

This links your existing backup to your account. Failure to do this may result in losing access to your account and all stored data.

On Monday, the US State Department said it was offering up to $10 million for information on the identities or locations of any of the people involved in the campaign. The reward is being offered under the State Department’s Reward for Justice program, or simply RFJ. The post said that in some cases, the attackers were abusing a Signal feature that allows users to create links to invite others to group discussions.

“Under this reward offer, RFJ is seeking information on UNC5792, a malicious cyber group associated with the Russian Federal Security Service (FSB) Border Guards and UNC4221, a malicious group of cyber actors working on behalf of the Russian military services,” Monday’s post read. “UNC5792 has conducted widespread phishing campaigns targeting Signal and WhatsApp accounts of US government officials, military leadership, and allied personnel.” The post continued:

In some instances, UNC5792 actors altered legitimate “group invite” pages to redirect users to a malicious URL that linked a UNC5792-controlled device to the victim’s Signal account. Although these malicious cyber activities did not exploit any security vulnerability in the platforms’ encryption protections, they have compromised thousands of individual commercial messaging application accounts.

The RFJ went on to say that the campaign has already compromised thousands of messenger accounts.

It may be hard for many to fathom the possibility of US intelligence officers, diplomats, or journalists falling for the scam. The fact remains that it only takes a moment for someone who is fatigued, sleep-deprived, or otherwise unguarded to act on the messages. Phishing remains one of the most effective means of gaining access to accounts, despite the relatively unsophisticated technical prowess required.

If someone provides their backup key in their response, they must generate a new backup recovery key. “To mitigate this risk, the user must generate a new Backup Recovery Key within the Settings control; this action will invalidate the previous key for all future backup downloads,” the FBI said in last week’s advisory. “However, please note that this does not prevent the actor from having already downloaded a backup of the original account.”

Messenger users should note that:

• • Legitimate CMA support services will not request verification codes within the application.
  • CMA support services do not send users links to "verify" or "restore" accounts.
  • They should never provide a verification code without confirming the request comes from a legitimate CMA communication channel.

As always, it’s a good idea to resist taking on the feeling of urgency that’s often conveyed in such messages. There is rarely a penalty for waiting an extra hour or two to act, even when responding to legitimate requests.

Read full article

Comments