skybrian's recent activity

  1. Comment on AI text watermarking is free and good in ~comp

    skybrian
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    This is counterintuitive because we know that word choices matter when we write, so how can choosing a different word not matter? Surely there are subtle grades of meaning to consider when picking...

    This is counterintuitive because we know that word choices matter when we write, so how can choosing a different word not matter? Surely there are subtle grades of meaning to consider when picking one synonym over another?

    That's going to depend on what words come before. In some positions, the next word will be highly constrained so it will always pick the next word the same way. There won't be any randomness at that position. At other places, the next word is a freer choice.

    This won't prevent the AI labs from working on improving AI writing style. As training gets better, LLM's will become more sensitive about word choices and less likely to choose randomly. So, the amount of freedom delegated to the random number generator will drop. Probably not to zero, though!

    2 votes

  2. Comment on AI text watermarking is free and good in ~comp

    skybrian
    Link
    From the article: [...] [...] [...]

    From the article:

    Scott Aaronson, while working at OpenAI, largely solved AI text watermarking together with Hendrik Kirchner.

    Here is how his solution works, or see Tenobrus’s version.

    1. AI outputs are not deterministic. The AI’s job is to pick the probability of each potential next token. The token is then chosen at random.

    2. By default you use a source of pseudo-randomness for each choice, since actual true randomness is annoying.

    3. To apply the watermark, you use an otherwise identical private source of pseudo-randomness derived from a secret key.

    4. Then, given enough text, a score is derived for howe well the choices fit with that particular pseudo-randomness source, versus a different source.

    5. You provide an API that lets anyone check for the watermark.

    [...]

    Google implemented this, including for Gemini 3.7 Flash, and they have been rolling out this feature since 2024. Google has done, for over two years, the exact thing Anthropic is now doing, except with a public detector, and Google confirmed in a test (n = 20 million) that there is no difference in user feedback.

    Anthropic quietly announced a week ago they were rolling out watermarking to comply with the EU Code of Practice. Since they don’t want to have to differentiate traffic sources, the marginal cost is zero, and watermarking is pro-social, this will apply to everyone. They then offered an FAQ of how it works.

    [...]

    The entire practical effect is: There will be an API that will tell you if a given piece of writing comes from Claude. That’s it. And yet.

    [...]

    The rest of this post is about exploring why people are Big Mad about this, in large part as a worked example of how people get worked up over approximately nothing.

    3 votes

  4. Comment on A study of the emissions of urban trees in ~enviro

    skybrian
    Link
    From the article:

    From the article:

    The main VOC emitted by trees is isoprene (2-methylbutadiene, the smallest unit in the terpene pathway, which in its polymerized form is natural rubber), and it’s responsible for the summertime haze in forested areas which existed before there were any automobile tailpipes or industrial smokestacks at all. Its emission is in fact a heat-stress response in plants and it is involved in resistance to reactive oxygen species - emissions fall to low levels in darkness and/or cooler temperatures. The authors studied ozone levels and VOC emissions in Beijing, and found that trees (especially willow and poplar species) contributed about 10% of the VOC total with human activities responsible for the other 90%. So far, that’s about what you would have expected.

    But on further study, it appears that the tree-derived VOCs account for at least half of the ozone-forming chemistry in the air, because of the reactivity of isoprene and related compounds with hydroxyl radicals. So the tree emissions are hitting far more heavily than that 10/90 split would make you believe, and that’s the surprise take-away from this work.

    Here are the details, though, that might get overlooked if someone writes a “Trees Responsible for Smog” headline. For one thing, it’s not all trees. Some species emit far more isoprene than others (the biggest culprits are the willows and poplars as mentioned, along with oaks and eucalyptus). That means that cities in Australia (where eucalypts are everywhere) have even more of a problem with this ozone source than do most cities in China. So secondly, these results don’t mean that Trees Are Bad, because they’re actually very beneficial in urban environments, not least for shading. It just means that we need to pay more attention to which kinds of trees we’re using, and to ease up on the isoprene emitters. Third, the main reason that tree emissions are this big a contributor now is because of clean-air emissions laws that have reduced the human contributions over the decades - if you’d looked at this in (say) 1950 the tree contributions would not have looked so impressive. Fourth, this most certainly does not mean that we can ease off on regulating our own emissions. As mentioned, nitrogen oxides are a key ingredient in ozone formation, and if we can continue to bring those down (and they’re almost completely our fault), ground-level ozone will improve no matter how many weeping willows are around. We planted the high-isoprene varieties ourselves for the most part, and if we didn’t keep dumping volatile nitrogen oxides into the system it wouldn’t be much of a problem anyway. It’s up to us to fix it.

    3 votes

  6. Comment on ForeFront Power completes its first Erthos solar energy system for the city of Fresno in ~enviro

    skybrian
    Link Parent
    Yes, it does matter. But the panels are getting cheaper, so if you have the room, you can install more of them to make up for it. As the cost of the panels themselves drops, all the surrounding...

    Yes, it does matter. But the panels are getting cheaper, so if you have the room, you can install more of them to make up for it. As the cost of the panels themselves drops, all the surrounding costs become more important, such as the cost of installing them.

    2 votes

  7. Comment on Git at any scale in ~comp

    skybrian
    Link Parent
    I see no reason to move, but the technical details are interesting and perhaps there will be an open source version someday? Someone could give an AI this page as a prompt to build a prototype.

    I see no reason to move, but the technical details are interesting and perhaps there will be an open source version someday? Someone could give an AI this page as a prompt to build a prototype.

    2 votes

  8. Comment on ForeFront Power completes its first Erthos solar energy system for the city of Fresno in ~enviro

    skybrian
    Link Parent
    My guess is they rely in part on wind being unable to get under the panels. And if they interlock, it seems like that’s a lot of weight, total? There are probably lots of interesting design...

    My guess is they rely in part on wind being unable to get under the panels. And if they interlock, it seems like that’s a lot of weight, total?

    There are probably lots of interesting design criteria. Maybe frost if it gets cold at night? Can it handle the ground freezing?

    They could do without steel framing, but they will need to prepare the site by flattening it.

  9. Comment on Offbeat Fridays – The thread where offbeat headlines become front page news in ~news

  10. Comment on NASA’s attempt to save the Swift telescope has failed in ~space

    skybrian
    Link
    From the article: [...] [...]

    From the article:

    On Wednesday, NASA announced that a rescue spacecraft that was meant to grab onto the space agency’s Neil Gehrels Swift Observatory and push it into a higher altitude will not proceed. With the rescue mission called off, Swift, which has observed distant, powerful explosions in the cosmos since 2004, is expected to burn up in the atmosphere later this year.

    [...]

    Last September, NASA hired a small company, Katalyst Space Technologies, of Flagstaff, Ariz., for $30 million to put together a mission to save Swift on an extremely rushed schedule. That limited the amount of testing that could be conducted to prepare for contingencies.

    In about nine months, Katalyst built the refrigerator-size rescue spacecraft named Link, which successfully launched on July 3.

    Link was moving closer to Swift but unexpectedly started tumbling on July 25. Katalyst was able to slow the spin of Link, and company officials were optimistic the spacecraft would be able to proceed with their schedule delayed by just a couple of weeks.

    But, on Wednesday, Ghonhee Lee, the chief executive of Katalyst, said the optimism did not prove out. The tumbling appears to have been caused by a malfunction with the maneuvering thrusters. Katalyst engineers used the main electric propulsion engines instead to get the spacecraft under control, writing new software using those to maneuver Link instead of the thrusters.

    That, however, did not provide sufficient precision, so the thrusters, most of which still worked, were brought back in operation. That led to the next problem. The electric propulsion engines and the thrusters both use xenon gas, and Link did not have enough fuel to complete the task of capturing Swift and pushing it upward.

    [...]

    Link will no longer attempt to capture or boost the space telescope but will still match the orbit of Swift, operating within a few miles to demonstrate capabilities that could be used for future missions. “I still hope that we’re going to be able to complete some elements of rendezvous and proximity operations over the coming weeks,” Mr. Lee said.

    14 votes

  12. Comment on Offbeat Fridays – The thread where offbeat headlines become front page news in ~news

    skybrian
    Link
    What it’s like to spend a weekend with more than 2,000 sets of twins [...] [...] [...] [...] [...]

    What it’s like to spend a weekend with more than 2,000 sets of twins

    Every August, for more than half a century, siblings who first met in utero take over Twinsburg for the Twins Days Festival, the world’s largest annual gathering of twins and multiples.

    [...]

    The celebrants arrive in twos, threes and fours, mirror images of each other or as dissimilar as Mutt and Jeff. Many are first-timers, but even more are repeat attendees stretching back years.

    [...]

    The festival is held the first full weekend in August and always in Twinsburg, about 25 miles southeast of Cleveland. In 1819, identical twins Moses and Aaron Wilcox changed the name of the settlement from Millsville, which honored a popular mechanism from that era, to Twinsburg, which celebrated a biological phenomenon now affecting about 3 percent of the U.S. population.

    The community first hosted an abbreviated version of the event in 1976 as part of a larger U.S. bicentennial celebration. Three dozen sets of twins showed up. Over the years, the festival has ballooned. It now stretches over three packed days, and the number of twins and multiples regularly exceeds 2,000 registered sets. (By Sunday afternoon, this year’s tally was 2,085; festival organizers will release a final count next month.) The identical and fraternal pairings arrive by car, plane, foot and baby stroller. A handful cross rivers, oceans and the international dateline.

    [...]

    The Double Take Parade is one of the festival’s marquee events, a 1.3-mile-long processional that, depending on the theme, can feel like a march of pop culture clones.

    [...]

    The twins and multiples who attend Twins Days every year say the festival is a place where they can feel normal and understood. Where they don’t have to explain the difference between identical and fraternal or A and B (first and second born). Where they can wear whatever they want, which for many means dressing exactly the same.

    [...]

    The festival dedicates a corner to research. This year, three universities, one plastic surgeon and Olay set up studies, taking advantage of the large sample size of twins — a windfall for researchers. Olay is studying how skin ages when genetics are not a factor.

    For 20 years, the Procter and Gamble brand has conducted facial imaging on about 100 sets of volunteers, in exchange for a swag bag of lotions, serums and sunscreen.

    8 votes

  13. Comment on ForeFront Power completes its first Erthos solar energy system for the city of Fresno in ~enviro

    skybrian
    Link
    From the article: [...] [...] [...] It's solar, but the aesthetic is rather "pave the earth." Nothing will grow there. Maybe aesthetics aren't that important.

    From the article:

    Erthos distills the complexity of solar energy systems into a modular, repeatable design. Unlike traditional ground-mounted solar energy systems supported by structural steel, Erthos’ Earth Mount Solar system places modules directly on the earth, which allows solar project developers to eliminate all the costs required to procure and install structural steel. Leveraging Erthos technology, ForeFront Power was able to reduce its total cost to develop its solar energy system and pass those savings to the City of Fresno in the form of lower electricity rates.

    ForeFront Power approached Erthos in 2023 when a combination of inflation and supply shocks caused the price of labor and materials to spike. The ForeFront Power team realized that the cost of a traditional ground-mounted system at this site would be significantly higher. This in turn would increase the cost of the electricity that ForeFront Power would sell back to the City of Fresno through a Power Purchase Agreement. Under the terms of the Agreement, ForeFront Power owns the system and charges the City a fixed, lower rate for electricity than the utility for 20 years.

    [...]

    Since the system entered commercial operation in late March 2026, the system has consistently outperformed expectations, operating at an average of 101% of expected energy production and has already delivered 862 MWh of energy to the City. ForeFront Power and Erthos continue to work closely together to optimize system performance. Both organizations are encouraged by the project’s early results and outlook for continued strong performance in the years ahead.

    [...]

    In addition to avoiding material and labor costs from structural steel, ForeFront Power was able to achieve a higher generating capacity per acre thanks to the unique architecture of Erthos systems. With no row spacing, Erthos offers the highest energy density of any solar architecture in the industry. Another unique feature of Erthos Earth Mount Solar system is that, although the solar modules are mounted flat on the earth, they can follow contours up to 15% slope, meaning they were adaptable to the natural topography of the Fresno site.

    [...]

    Custom-designed for use on an Earth Mount Solar array, the ErthBot cleaner is deployed nightly as needed and returns to its charging dock after each use, ready to be deployed again the following evening. Erthos handles the operations and maintenance of the ErthBot as part of its Energy Services Agreement with ForeFront Power.

    It's solar, but the aesthetic is rather "pave the earth." Nothing will grow there.

    Maybe aesthetics aren't that important.

  15. Comment on Git at any scale in ~comp

    skybrian
    Link
    From the article: [...] [...] [...] [...] [...] [...]

    From the article:

    Over the years, companies that tried hosting Git repositories at scale noticed that this packfile-based design was a major limitation on both availability and scalability. Packfiles are large binary files that must exist on a filesystem for Git to access them. The simple approach of having an HTTP server in front of a repository on disk has a very low ceiling. Ideally you'd want the repository to exist on many disks and many machines (this lets you run many Git operations in parallel, and keeps your repository available when a server crashes). But how do you do that?

    There are broadly three possible approaches to accomplish this, in increasing order of complexity: distribute the filesystem, distribute the packfiles, or distribute Git itself.

    [...]

    Spokes was originally developed at GitHub around 2013, and it has since become an industry standard. Most Git hosting services use a variant of the Spokes approach (application-level replication for Git repositories) in their architecture. The main reason Spokes has worked well for many years is that it made three fundamental choices that, over time, have been proven to be optimal:

    [...]

    Spokes is a consensus-based distributed system. It works by storing several copies of your Git repository on different servers. Whenever you push new data, an orchestrator fans out your push so that every instance of your repository receives a copy. The "fan-out" is synchronized with a classic consensus algorithm called 3PC (three-phase commit) so that a push is only accepted if a majority of the nodes acknowledge it.

    [...]

    This scalability constraint also applies the other way. When agents work with Git repositories at scale, they often operate outside of a monorepo by creating vast numbers of small repositories, many of them throwaway, and most of them barely touched. Spokes struggles here because it still requires three replicas for every one of these repositories. Three mostly idle replicas, which cannot be trimmed down because then the system wouldn't be fully consistent and data loss would be possible. With three-phase commit, the floor is always too high, and the ceiling too low.

    Another flaw, impossible to see up front, but painfully obvious after having suffered through it, is that Spokes can be rough to operate at scale. Because the repositories on disk are always the source of truth for consensus, every copy of every repository is very important. You have to treat repositories as pets, not cattle.

    [...]

    Continuity is a simple system (a system cannot be easy to operate if it is not simple). The core primitive behind it is a write-ahead log, which we store in S3-compatible object storage. In production, we run directly on S3, but we designed it so it can be deployed on any cloud.

    [...]

    The local copy of the repository is, of course, a normal Git repository stored on a very fast NVMe drive. We do the same thing that Spokes does because I think Spokes got that exactly right. It allows us to reuse all the amazing OSS work of the Git community, including the upstream Git client and its many performance optimizations. It lets us focus on shipping new features, instead of doing weird stuff with Git.

    [...]

    We've seen that one thing that makes a Spokes cluster hard to operate is that it's very important to keep track of the location of every repository on each server. Continuity does this very differently. Where does every repository live? The answer is "anywhere". It doesn't matter! We treat repositories like a warm cache on disk, but the source of truth is always the write-ahead log in S3. The system is stateless, and there are no routing tables (and no relational database to operate — hashtag blessed). If a repository is missing from the local disk when accessed on a host, we just materialize it from the WAL. We can do this very efficiently, but of course we don't want to do this all the time, because it'd be wasteful. In production, we use rendezvous hashing to map a repository ID to the list of nodes where we expect it to be. All the state we require to route repositories is the repository ID and the current set of healthy nodes in a cluster. But if this state gets out of sync (e.g., a node becomes unhealthy), that's perfectly fine too. We'll just materialize the repository on whichever node comes next.

    4 votes

  17. Comment on Ukraine planned to swarm Moscow airports with AI-guided drones (gifted link) in ~society

    skybrian
    (edited )
    Link
    Maybe this explains the leadership shakeup? I guess they went with attacking Wildberries warehouses instead. Neither side in this war seems quite willing yet to escalate it into a wider war, so...

    Both sources told me planning for the operation was halted in July, when Zelensky abruptly fired its mastermind, Defense Minister Mykhailo Fedorov. As the architect of Ukraine’s military drone program, Fedorov had worked on the plan for most of this year, keeping it a secret even from some of his closest aides. He helped assemble a team of Ukrainian computer programmers to develop the AI guidance system, and he secured financing from Ukraine’s allies in Europe to produce the autonomous drones at scale, the two sources said.

    Maybe this explains the leadership shakeup? I guess they went with attacking Wildberries warehouses instead.

    Neither side in this war seems quite willing yet to escalate it into a wider war, so it's happening slowly as they test the boundaries. But escalation is a risk and civilian aviation seems rather vulnerable if the drone war gets further out of hand.

    9 votes

  18. Comment on Founder of collapsed Chinese property giant Evergrande sentenced to life in prison in ~finance

    skybrian
    Link Parent
    I would expect there to be a deposit held in escrow. I wouldn’t expect the builder to effectively be borrowing money from the home buyer. They’d get loans from a bank for that, or maybe raise...

    I would expect there to be a deposit held in escrow. I wouldn’t expect the builder to effectively be borrowing money from the home buyer. They’d get loans from a bank for that, or maybe raise money from investors.

    4 votes

  19. Comment on Founder of collapsed Chinese property giant Evergrande sentenced to life in prison in ~finance

    skybrian
    Link Parent
    I’m wondering why this pre-paying was a thing at all. It seems like a weird thing to do to use a real estate company as a bank if you’re saving up for an apartment? Why were there no government...

    I’m wondering why this pre-paying was a thing at all. It seems like a weird thing to do to use a real estate company as a bank if you’re saving up for an apartment? Why were there no government protections?

    2 votes

  20. Comment on Moderna, Merck say mRNA vaccine prevents melanoma from returning in ~health

    skybrian
    Link
    From the article:

    From the article:

    The study is the most advanced of a number of trials testing the approach against a variety of cancers, including lung, bladder, kidney and pancreatic cancer. While small trials have shown the promise of the approach, the Moderna and Merck trial was seen as a bellwether in demonstrating the technology — and a first step toward transforming cancer care with treatments that are individualized to a person’s tumor and that may ultimately be able to stay ahead of it as it changes.

    4 votes