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105

What Is an Electronic Sackbut?

from IEEE Spectrum [alt+shift+b] in science

If you, like me, think of musical synthesizers as an artifact of 1970s rock and disco, then you, like me, will be surprised to learn that the first electronic synthesizer predates those genres by several decades In 1945, Hugh Le Caine, a physicist at Canada’s National Research Council, began working in his spare time on a single-channel musical instrument he dubbed the Electronic Sackbut. He was intrigued by the fact that the three auditory sensations associated with music—namely, pitch, loudness, and timbre—had counterparts in electronics—namely, frequency, amplitude, and the harmonic spectrum obtained by Fourier analysis. To demonstrate those qualities, Le Caine created a synthesizer that mimicked, among other things, a brass horn known as the sackbut. It could also synthesize other horns, as well as string and reed instruments. He envisioned using the electronic sackbut in live performances, to play orchestral, big band, and experimental jazz music. Here’s a recording of one Le Caine composition, “The Sackbut Blues”: Short presentation of the 1948 sackbut: the sackbut blues www.youtube.com What is a sackbut? All of my friends who are into Renaissance music love the 2004 Coen brothers film The Ladykillers because it contains one of the few modern references to the sackbut. The original sackbut emerged in the 15th century, and it had a telescopic slide used to change pitch. It fell out of favor by the 18th century, only to be reborn as the modern-day trombone. Le Caine chose to name his synthesizer after a thoroughly obsolete instrument to “afford the designer a certain measure of immunity from criticism.” That is, the electronic sackbut was its own invention, not an imitation of a known sound. Hugh Le Caine demonstrates the left-hand control for timbre and the right-hand control for pitch and volume.National Research Council Canada Archives Le Caine’s first electronic sackbut [shown at top] had all of the aesthetic roughness of an experimental...
1st Feb 2024

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Guarding the Gates of Knowledge

A recent scroll through social media got me thinking about trust. About half my feed was filled with AI slop that astute users would call out as being machine-generated, often to the embarrassment of the rube who unknowingly spread it and sometimes to the delight of the poster who shared it deliberately because they found it amusing or useful for sowing confusion. Remember the good old days of GPT-3 when we could ask the chatbot anything and it would almost instantly and very confidently spit back a plausible but false answer? That’s when the word “hallucination” as applied to AI answers entered the lexicon. Six years and several versions of a few different chatbots later, I still can’t trust the answers I get, even though Claude or Gemini often do useful work for me. That’s the thing about current AI: Trust but verify. And verify you must. Apply that maxim at scale to maintain the integrity of the scientific record and you get an idea of the challenge facing publishers of peer-reviewed scholarship. In “I Used AI to Fake a Scientific Paper,” freelance writer and doctor of applied mathematics Benjamin Skuse tells the story of the human gatekeepers trying to beat back the rising tide of AI slop by attempting to get his own AI-generated papers past IEEE’s defenses. “He basically hit ‘run experiment’ and ‘write paper.’ And then he didn’t do a damn thing to it.” —Eliza Strickland As features and AI beat editor Eliza Strickland told me, Skuse was surprised at just how effortless it was to generate a paper that was more or less plausible and more or less science. For one of his experiments, “he basically hit ‘run experiment’ and ‘write paper,’” she said. “And then he didn’t do a damn thing to it. He just launched it into the maw of the publishing engine.” Skuse discovered that the combination of IEEE’s human-review processes and research-integrity checker programs are currently keeping pace in what amounts to a cat-and-mouse game against people using free tools. But the more advanced LLMs are no longer making the same dumb mistakes the free versions do. That leaves publishers locked in an arms race between increasingly plausible slop and the systems aimed at detecting it. Scholarly publishers aren’t the only ones trying to hold the line against slop. So is that global depository of human-generated knowledge, Wikipedia. For this month’s Five Questions, Strickland interviewed Ellia Lebleu, a founding member of WikiProject AI Cleanup, a volunteer effort to detect and delete AI-generated material from the platform. Lebleu’s team is confronting the same problem as commercial publishers, but with fewer people and fewer tools. “Wikipedia is known as a repository of human-generated information, and they want to hold on to that,” says Strickland. “Who knows how long they’ll be able to do that.” If we can’t collectively assume that the scientific record is trustworthy or that basic facts about the world are accurate, then our understanding of what is real unspools into uncertainty. Perhaps that delights quantum scientists and the grifters who thrive in an information environment where there is no shared reality. But that uncertainty ultimately undermines trust in the institutions that exist to curate the corpus of human knowledge and to promote the advancement of science and technology for the benefit of humanity. Or maybe in a world where AI is doing the science and writing the papers, it won’t matter whether or not humans trust the outputs. As Strickland put it, “Doesn’t it just feel crazy that we’ll have AI writing for other AIs at some point? We’ll just get left out of the loop.”

3 days ago • 1 votes
Electricity Theft Is Rampant, but Delhi Found a Fix

It’s disheartening how much power gets generated and then promptly lost as it travels through grid networks. This leaking of electricity happens when it vanishes as heat as well as when it is pilfered by thieves and nonpaying customers. More than half of the countries that track these metrics lost at least 10 percent of their electricity in 2023, according to the World Bank. Losses topped 20 percent for 24 of those nations. Two countries lost more than half of what they generated. With numbers this high, cutting down on losses makes sense. Electricity demand is rising beyond what many grid operators can supply; reducing waste would help meet some of that demand without having to build new power plants. Plus, when the power comes from fossil fuels, any loss means emitting even more greenhouse gases into the atmosphere. And electric losses hit the bottom lines of power providers, which ultimately pass those costs on to everyone else. The trouble is, reducing electricity losses is a hard and expensive process that takes a long time. Typically, the less maintained the grid infrastructure, the more electricity that’s lost. And the more fragile the region’s law enforcement and government, the more prevalent the power theft. Natural disasters and war make things worse. Delhi’s Power Grid Comeback Fixing a power grid requires a systemic approach across many sectors. There’s no one technology that will solve the problem. At the outset, the obstacles to success may feel insurmountable. Equipment across entire grid networks must be updated. Multiple arms of government must agree to reforms and coordinate to ensure power providers are set up to succeed. Regulations must be written or revised, investments made, cultures changed. The city of Delhi did all those things. Over the past 25 years, it cut its electricity losses from about 50 to 5 percent. How the city pulled off that impressive feat is the focus of “The Epic Comeback of Delhi’s Power Grid” by Mini Shaji Thomas, an electrical engineer at the university Jamia Millia Islamia who has lived in Delhi since the 1990s. She gives us a view from the inside—as a resident and a power systems expert. Delhi is a shining example, but some other regions have significantly lowered electricity losses over the last quarter century too. The country of Georgia went from losses of over 16 percent in 2002 to about 8 percent in 2023. In Singapore, losses dropped from 6.6 percent to a nearly nonexistent 0.2 percent over the same time period. Global Electricity Theft Crisis But there are many parts of the world where electricity losses remain a problem or have gotten worse. In Jamaica, where power theft is rampant, losses have hovered between 21 and 28 percent for years. Argentina’s losses nearly doubled between 2015 and 2023, going from an all-time low of about 12 percent to an all-time high of nearly 24 percent. The main problem: Transmission and distribution companies lacked the capital to maintain and upgrade their networks, which left equipment operating under stress. A delay in the installation of smart meters has allowed thieves to more easily siphon power and tamper with meters. Thomas says she hopes her account of Delhi’s grid comeback will serve as a blueprint for others. It’s possible to replicate the sweeping changes Delhi made, she says. But it “requires a concerted effort from all stakeholders, customers, the utility, the government, and their employees.”

1st Oct 2026 • 1 votes
Cash in on the AI Boom by Renting Out Your Spare Compute

If you own an at-home server, a gaming computer, or just a laptop that doesn’t get much love, listen up. You can now put that spare computing power to use and earn some passive income in the process. AI companies are hungry for more compute to run AI inference—the process of using a pre-trained model to respond to queries—and they’re willing to pay you for it. “Imagine Uber or Airbnb, but for AI inference computing tasks,” says Ilman Shazhaev, founder and CEO of Far Labs, based in Abu Dhabi. The AI boom has spurred on construction of massive data centers, often damaging local communities by raising electricity prices, straining local water resources, causing environmental damage and noise, and being just plain ugly. Huge data centers are likely not going anywhere—training new frontier models and running AI models from leading companies will likely still be the purview of these behemoths. But now, several companies are providing AI inference on smaller, mostly open-source models. They are running inference on pre-existing computing power spread throughout homes and small businesses, and compensating owners. “Everyone thinks the only way to do it is data centers. And data centers are extractive for the communities in which they’re built, and they don’t return services or taxes or much of anything to the people there. So why not just turn this whole thing on its head?” says John Federico, founder and CEO of Evolving Edge, in Austin, Texas. “The compute power is out there. If you can orchestrate it, then you’re actually adding value to those communities directly.” The idea isn’t entirely new: From 1999 to 2020, a volunteer-based project called SETI@Home used spare computers to search for signs of extraterrestrial life in radio telescope data, for instance. But now, commercial companies are eager to use the same strategy. Shazhaev’s Far Labs is launching its platform Far AI in the coming weeks, while Federico’s Evolving Edge is currently in open beta. Other companies, like Bless Network, Salad, and Gradient have started to provide similar platforms over the last year. Connecting to the network Federico has been a computer hobbyist since youth, and he has amassed a whole server in his basement to run his projects. “It just hit me one day, there’s all this talk about not having enough compute, and I just thought, well, 92 percent of the country has broadband, and you have people like me who have mini data centers in a closet,” he says. Federico sees the potential hosts as people much like himself who have already invested in home servers, and he aims to make the process of selling spare compute as seamless for them as possible. “Sign up for the program, install an application,” Federico says. “All we want to do is run jobs on your machine when you tell us we’re allowed to. The only thing we do is monitor the resource usage. And of course, you can give us a schedule.” With a large enough network of devices, the platform would have compute available whenever it’s needed. Privacy and security are primary concerns for such hosts. To reassure the users that their local data is secure, and that no malware will be downloaded to their devices, the team open-sourced their scheduling software. “The node software is open source, so anyone can look at it, see what it does. All we want to do is run jobs on your machine when you tell us we’re allowed to,” Federico says. Far Labs’ Shazhaev explains that the company’s software is designed around a principle known as “least privilege”: granting both the host and the user the least access possible to accomplish the task. Inference runs as an isolated workload with authenticated, encrypted communication and explicit limits on the GPU, CPU, memory, storage, and network resources it may use. 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But if that fails, there are tools to split a single inference task over multiple GPUs or CPUs. Evolving Edge is using an open-source tool called Ray to perform this splitting, while Far Labs has developed its own proprietary software that not only splits the workload, but wraps the splitting in a layer of security and reliability-providing software. “One thing we have done is we shared the model,” Shazhaev says. “We take the model, we cut it into many pieces, then these pieces will be distributed through different devices. And we have an orchestrator and a load balancer which manage the task flow, so each device processes a part of the task. Then we combine the answers in the main brain, the orchestrator.” Through a combination of using smaller, more task-specific models, and splitting larger models between disparate devices, the teams claim they can perform inference much cheaper than a traditional data center “because we don’t have capital expenditure,” Shazhaev says. Gaming PCs are a common source of spare computational power in the home. Dizzaract The distributed advantage Not only is it cheaper to run inference this way, it is also more reliable, Shazhaev claims. The companies have access to a distributed network of computing resources, rather than one giant device that can experience outages. Shazhaev compares this to cryptocurrencies, and their resilience through decentralization. “Today, to shut down Bitcoin, you need to nuke the whole planet. Here, we have the same concept,” Shazhaev says. Federico explains that this resiliency would be beneficial not just for AI inference, but for all kinds of applications, including smart cities, environmental sensors, autonomous vehicles, and more. During an Amazon Web Services outage in 2026, for example, smart beds were stuck in their upright positions and their users couldn’t adjust them. Federico says that a distributed network where everything doesn’t need to be routed through a single data center, say, in Ashburn, Va., would make those kinds of outages much less impactful. “We could lose 100 nodes in a network of 250,000 and it wouldn’t matter,” he says. If the network of user devices is substantial enough, every job can be routed to a nearby device, decreasing the latency. Far Labs claims a latency of 100 milliseconds or less on its platform. The lower cost and lower latency of this approach may even enable new use cases, such as in-game AI video generation, which is currently prohibitively slow and expensive. “OpenAI last year had $30 billion in revenue, but they closed the financial year at an $8 billion loss. Why? The official reason is due to the high cost of inference,” Shazhaev says. “And those are mostly text models. For gameplay, you have audio, video, animations: It’s heavy data, and you need real-time responses. So, we’ve been trying to solve this issue.” All of these companies are trying to tap into an untapped resource of local compute, and hoping it’ll benefit the device hosts and users alike. “All these big guys are running around building data centers,” Shazhaev says, “but I believe there is enough compute power that already exists in the world.”

1st Sep 2026 • 1 votes
Fridays With Bob

When I started at Spectrum 25 years ago, a senior editor suggested that I find a “rabbi,” by which he meant someone who could mentor me in how EEs approach problems and evaluate potential solutions. I didn’t find one right away. Then in 2005 we decided to do a special report, focusing on the challenges of enterprise software development. I suggested we invite IEEE Life Senior Member Robert N. Charette, a self-described risk ecologist, prolific book author, and leading authority on risk management and software engineering, to explore in our pages the myriad reasons software projects fail. His seminal article “Why Software Fails” is still read in university engineering classes today. IEEE Life Senior Member Robert N. Charette is one of IEEE Spectrum’s most prolific authors.Robert N. Charette It was, as they say, the beginning of a beautiful friendship. I had found my rabbi, one who shared my love of writing. We settled into a rhythm that would last more than 20 years, talking on Friday mornings about a range of topics including the growing ubiquity of software in our lives. So when I became Spectrum’s website editor in 2007, he was the first contributor I tapped to start a regular blog (remember those?). The Risk Factor was born and over the course of more than 10 years and 1,750 posts, Bob chronicled hundreds of software debacles, culminating in “Lessons From a Decade of IT Failures,” which won a Jesse H. Neal Award for Best Infographics in 2016. Ironically, yet predictably, those infographics were created in a software package that is no longer supported and thus are lost to the bits of time. “I like the expression on the fish just before it’s going to be swallowed by the heron.”Robert N. Charette Bob, however, was not a one-trick pony. In between his full-time job running his two management consultancies and raising a future biochemist and a future civil engineer, his daughters Maura and Megan, he also wrote many deeply reported and insightful articles. These include last year’s “The Doctor Will See Your Electronic Health Record Now,” the eye-opening 12-part series and e-book The EV Transition Explained, and my personal favorite “Automated to Death,” about the deadly consequences of the automation paradox as manifested by the cyberphysical systems that pilot planes, trains, and automobiles. “The young bald eagle I photographed in September 2024 had bands that I could read which identified it as a female born in May 2024, near Lexington Park, St. Mary’s County, Maryland, about 65 miles away from where I live.”Robert N. Charette His main goal all along has been to make software visible, as he told me one Friday in July. “Software is all around us, but we don’t recognize it at all,” he said. “I really wanted my stories to help people better understand complex software systems. You can’t see software, you can’t touch it, you can’t taste it. You may feel the consequences of software failure, but you never see the reason itself.” When he told me that he was hanging up his hat as a contributing editor to focus on nature photography and to write a handful of fictional trilogies, including one entitled “The STEM Murders” featuring an engineer-turned-detective and his rabbi, I asked him which of his Spectrum articles had the biggest impact. “The hummingbird I caught with the yellow of a road curb behind it.”Robert N. Charette He singled out the 2013 feature “The STEM Crisis Is a Myth.” “Spectrum gave me a platform to question the assumption that we needed more STEM graduates. Until then, people didn’t really realize how much of the STEM crisis was a mythology that was perpetuated by employers and the academic community and was foisted on the IEEE community,” he said. Charette made a career of questioning assumptions. The best way to mitigate risk, he told me as our Friday chat drew to a close, is to be careful making assumptions in the first place. “My main risk maxim is assumptions made are risks accepted.”

1st Aug 2026 • 1 votes
The Orbital Data Center Hype Machine Is Already in Orbit

“The lowest-cost place to put AI will be in space, and that will be true within two years, maybe three at the latest,” SpaceX founder Elon Musk told the World Economic Forum in Davos this past January, as his company was preparing to go public. Later that month, SpaceX filed an application with the Federal Communications Commission for an orbital data center constellation of up to 1 million satellites in low Earth orbit, 500 to 2,000 kilometers above Earth. And just three days before the IPO, he discussed some initial design specifications for a new AI-1 satellite data center in a video interview. Musk is prone to hyperbole when it comes to timelines. Full self-driving cars by 2017. First human mission to Mars in 2024. Ten thousand Optimus humanoid robots by the end of 2025. Et cetera. For orbital data centers, which he says will be a cost-effective alternative to terrestrial data centers within three years, the math won’t make sense for several years, if ever. Consider this: There are roughly 14,500 active satellites in orbit. Musk’s Starlink constellation accounts for about two thirds of those. Both the launch cadences and satellite-manufacturing capacity would have to scale up astronomically to deploy a million orbital data center satellites. For context, there have been roughly 7,000 orbital launches in all of human history. To loft 1 million satellites into low Earth orbit on SpaceX’s Starship, which is designed to carry up to 60 satellites per vehicle, would require 16,666 launches exclusively devoted to satellite deployments. Considering that SpaceX launched a record 165 orbital missions in 2025, even at 10 times that cadence, it would take a decade. And how long would it take to build 1 million satellites, given Starlink’s current pace of around 4,000 per year and a generous tenfold increase in capacity? Short of a manufacturing revolution, try 25 years. The reality is that the vision of massive constellations of orbital data centers is nowhere close to being realized. As this month’s cover story, “Why Orbital Data Centers Are So Hard” by Andrew Cavalier of ABI Research, makes clear, the reality is that the vision of massive constellations of orbital data centers is nowhere close to being realized. Dina Genkina, IEEE Spectrum’s computing and hardware editor, put the idea into perspective: “Starcloud (a startup that has applied to the FCC for an 88,000 orbital data center satellite constellation) sent one Nvidia H100 GPU in space so far. Their radiator was too weak to let the chip run at full power.” As Cavalier shows, cooling even a single Nvidia H100 GPU in space is difficult: It draws 700 watts, which will require 1.4 square meters of radiator at 60 °C. A 40-kilowatt rack of servers will need an 80-m² radiator; a 100-megawatt data center will require 2,500 of those radiators. Some astronomers are understandably concerned that a million satellites with giant radiative wings would blot out the stars. So if the economics doesn’t make sense, if the chips are at the mercy of the radiative ravages of space, and if humanity will lose its view of the stars, not to mention increasing the risk of triggering the Kessler syndrome, why are the hyperscalers hyping orbital data centers? Genkina offered the obvious answer: sweet, sweet moolah. “The Elon Musk part of it is honestly genius because he’s got xAI building the data centers, SpaceX sending them to space, and Tesla building solar panels,” Genkina says. “It’s almost like he’s paying himself.” Two Analyst’s Views of SpaceX’s Proposed AI1 Data Center Satellite Michael Pierce, Principal at Technology Strategy Partners Musk’s timelines are notoriously overly ambitious, but I think SpaceX’s orbital data centers might reach cost parity with terrestrial data centers in 5 to 10 years. The Starlink laser-link network already exists as the communication backbone for any SpaceX compute constellation, and that infrastructure is what no new entrant can replicate quickly. The chip-agnostic payload design probably reflects their disclosed difficulty securing AI silicon as much as any modularity philosophy. My view is that the only realistic near-term application is a SpaceX mega-constellation for inference. Training workloads likely cannot tolerate the synchronization and latency constraints of a distributed orbital system. Our report analyzed the market from the integrator’s vantage point, but AI1 is what it looks like when one player has assembled all the necessary advantages simultaneously. The question is whether the terrestrial data center industrial base will degrade or improve on economics. I don’t have insight into SpaceX’s internal costs, as opposed to public pricing, on all their components, so it’s hard to say if they’ll completely dominate or not. Even if they are not cost competitive with terrestrial data centers for another 5 to 10 years, it may simply be faster to get new compute that just happens to be in space. Matt Hasan, AI strategist and independent consultant My initial view is that AI1 does not fundamentally change the rationale for space-based data centers as much as it changes the timeline and scale. The underlying drivers remain the same: escalating AI compute demand, growing power constraints on terrestrial grids, and the desire to colocate energy generation with computation. What AI1 does signal is that the concept is beginning to move from theoretical discussion toward engineering and capital allocation decisions. The announcement adds credibility to the idea that hyperscale computing infrastructure may eventually expand beyond terrestrial constraints rather than simply competing for increasingly scarce grid capacity on Earth. That said, significant economic and technical questions remain. Launch costs, maintenance, hardware replacement cycles, thermal management, latency-sensitive workloads, and overall system economics will ultimately determine whether space-based data centers become a mainstream extension of AI infrastructure or remain a niche capability for specialized applications. The key development is not that these questions have been resolved, but that major industry players now appear willing to invest resources toward answering them.

1st Jul 2026 • 1 votes

More in science

Windows Are Absurd

[Note that this article is a transcript of the video embedded above.] Have you ever thought about windows? Like really considered the idea? If we hadn’t been exposed to them our entire lives, it might seem like kind of a bizarre concept. On the face of it, windows are about light. But it’s more esoteric than that, especially now that we can make our own light. We want to be inside, but not all the way inside. So we put holes in the wall. It’s a heck of a trade-off: you get light and a view of the outdoors, but it comes at a cost. Not just the cost of the glass itself, but also the structural changes they require and their effects on ventilation, sound, cooling, heating, safety, and security inside a building. As simple as they seem, windows are a technology of sorts. And like a lot of building science, we’ve slowly been making progress, readjusting those tradeoffs and giving us the benefits without so many of the costs. I love to pick a relatively innocuous part of the built environment and really take a close look. So, I’ve built a few demonstrations in the garage to show you how far the science of glazing has come. I’m Grady, and this is Practical Engineering. Glass is not a good substitute for an exterior wall, in many respects. If you take some wall away and replace it with a window, you’re not trading like-for-like. For one, you never accidentally throw a baseball through a brick wall. But it’s especially true when it comes to heat. And this is a pretty big deal because we collectively spend vast sums of money, resources, effort, and energy on maintaining a comfortable thermal climate inside our buildings. Almost all the time, in almost all the places, the temperature outside of a building is different from the temperature we want it to be inside. But the laws of physics (also all the time in all the places) are constantly working to equalize those temperatures. We usually categorize the flow of heat into three separate modes. Conduction is heat moving through solid objects, atoms or molecules that are tightly packed, transmitting energy to their neighbors directly by vibrating against each other. Convection is heat transfer via the movement of a fluid like air or water. Radiation is heat transfer through electromagnetic waves. Since it is literally light, radiation doesn’t need a medium. All three play a role in the walls of buildings. And of course, it works both ways: sometimes it’s too hot outside and you want to keep that heat out. Sometimes it’s too cold and you want to keep the heat in. Any movement of heat from inside to out or vice versa is a flow of power, just like we measure with electricity. If you have 500 watts of heat flowing out of your house, you essentially need a 500 watt heater inside to make up for the loss and maintain a steady temperature. And just like voltage is a difference in potential that drives electrical current, heat flow is driven by a difference in temperature. The bigger that difference, the greater the flow of heat through a given wall. Continuing the electrical metaphor, insulation is the generic term we use to describe materials that resist the transmission of heat from one side to the other. It makes sense that we put it in our walls. In the US, we use R-value as a measure of this resistance. This is kind of a cursed unit of measurement, so I’m going to gloss over the scientific definition. But, a typical exterior wall assembly will usually have an R value between 10 and 25, depending on climate and how new the building is. A simple pane of glass has an R value of about 1. Let me show that to you. I built this box of foam insulation in my garage. Inside, I have a 25 watt ceramic heat emitter. I can close this up and wait for the temperature inside to stabilize. When that happens, we can assume that the heat going into the box is the same as the heat flowing out. Okay, this has pretty much settled out, and you can see that the difference between the interior and exterior probes is about 43 degrees Fahrenheit, I think that’s around 24 celsius. This is R-5 foam, soif you do the math for a perfectly sealed box with these dimensions that should be right around 50 F, 28 C, um, so accounting for the imperfections in my setup, like this, uh, terrible tape seal, that’s actually pretty close. Um, so now I’m going to swap this lid out with a pane of glass, and we’ll set this going again. Okay, this has settled out. And you can see that the temperature inside the shop hasn’t really changed, but the temperature inside the box has gone down a lot compared to the foam lid. The difference is about 22 F, which I think is around 13 C. So, just replacing one side of the box with glass instead of foam, it takes a much smaller difference in temperature to move that same 25 watts out of the box. I’m sure you see the issue here. If we want windows in our buildings, it comes at a cost of thermal efficiency. For every square foot or square meter of exterior wall that we swap with single pane windows, heat will move through that space roughly 10 to 25 times faster. So, we rarely use single-pane glazing anymore. Almost all modern windows use two, and sometimes even three panes of glass with a sealed air gap between them. Sometimes this gap is filled with a heavy gas like argon or krypton that has lower conduction and convection. There are even vacuum insulated panels that have no air inside, eliminating convection entirely. It seems like a simple change, but it makes a pretty big difference. I happen to have a double-pane glass unit, so we can try the experiment again. Okay, this demo has settled out now, and you can see that the temperature difference is right at 30 F, 17 C. Remember with the foam lid it was about 43 degrees and with the single pane it was around 23 degrees. So this is basically right in the middle. It’s not as good as when there was no window, but it’s a lot better than the single pane of glass. This varies a lot with details of the frame and coatings. But very generally, modern double-pane windows can double to quadruple the insulative value of a single pane of glass, and that can make a huge difference in a building with a lot of them. This idea of a sealed air gap between panes comes with one problem. If you’ve ever brought a bag of chips on an airplane, you know what I’m talking about. If the glass manufacturer is at a low elevation and the window’s going to be installed somewhere much higher, you end up with an overpressure situation between the panes compared to the barometric pressure. That can cause them to bow out and even fracture. In some cases, manufacturers will actually dial in the pressure for the altitude of the final destination. Another option is to install a capillary tube that equalizes the pressure inside and out. These are very narrow diameter and long tubes meant to reduce the amount of moisture that diffuses between the panes, which would otherwise lead to condensation inside the unit. Insulating glass panels help reduce heat conduction and convection, but that’s not the only way heat gets into and out of a building. The whole point of a window is to let in light, and we already learned that heat can move as electromagnetic waves. Of course, if we block visible light through a window to avoid heat transfer, that kind of defeats the purpose. But radiation also happens at other wavelengths on the electromagnetic spectrum. Specifically, for the temperatures we deal with on a day-to-day basis, most of the thermal radiation happens in infrared: wavelengths longer than visible light but shorter than microwaves. Even within that range, there are big differences in how the waves interact with matter. That’s particularly true for windows. Typical stuff at ambient temperatures like a sun-baked driveway or human body, emit thermal radiation mostly in the far-infrared spectrum. This is the stuff you can see on a normal infrared camera. And even though glass is designed to let visible light through, it is almost completely opaque to longwave infrared light. Try looking through a window with an infrared camera and you just see the window itself, not anything beyond. It’s cool to think that if our eyes worked a bit differently - if they were tuned to a slightly different part of the electromagnetic spectrum - a glass window would be entirely useless. And it seems like it would be a good thing for our thermal problem, preventing heat from transferring through. Unfortunately it’s not that simple. Glass isn’t just opaque to far-IR; it’s also highly emissive. That means it mostly absorbs thermal radiation rather than reflecting it. So, the radiation doesn’t come directly through, but it does warm the glass, which can then just conduct through the pane and reradiate it where you don’t want it to go, whether inside or out. It’s basically radiation with extra steps. On the shorter wavelength part of the spectrum we call near IR, it’s a little different. The main source of near IR radiation is the sun, and like visible light, that radiation can pass directly through most glass. This is how greenhouses work. The shortwave radiation passes right through where it can warm the stuff inside. But the stuff inside radiates longwave IR, which can’t pass back out through the glass. So, windows are kind of a two-way half-door for far infrared (since they absorb and reradiate it in both directions) and a one-way door for near infrared, but we can do better than that, mostly through low-emissivity or low-e coatings. These coatings essentially convert a pane of glass into a mirror for IR. And you can see the difference really well with an IR camera. You still get some reflections with an uncoated pane, but the difference is obvious when you put a coated pane next to an uncoated one. But this gets a little tricky, especially when it comes to near IR. If you live in a cold climate and your main use of energy is heating, you’re happy to invite as much sunlight as you can get inside. You don’t want to reflect the near IR. The opposite is true in warm climates. Fortunately, manufacturers can tune the coatings according to the climate. You can reflect shortwave radiation if you’re worried most about cooling, or you can let it in to gather more heat inside. Window manufacturers also sometimes vary which face is coated. In warmer climates, you can coat the inside of the outer pane, called “surface 2,” reflecting the IR before it crosses the gap to keep it from warming the air between the panes. In cooler climates, you can put it on “surface 3” to reflect the long-waveshort-wave IR back into your house without it having to cross the air gap. Making windows more thermally efficient isn’t the only use for glass coatings. If you’re like me, there’s a good chance you have the Merlin app installed on your phone. I think it’s a bit of an inevitability that once you reach a certain age, you start getting interested in birds. Unfortunately, one of the largest human-caused sources of bird mortality is actually windows. At certain angles, windows work essentially like mirrors, reflecting the trees and sky, and birds (bless their hearts) can’t always tell the difference. It can happen the other way too. Sometimes a bird will see something inside a building or all the way through two windows that they want to fly toward, not recognizing that there’s solid glass in the way. For you and me, walking into a glass pane like a sliding door is embarrassing, but for a bird flying at much higher speeds with tiny, hollow bones, it is often fatal. McCormick Place Convention Center on the lakeshore in Chicago may be the most famous case study. In an average year, monitors would find around 1,000 dead birds around the building from collisions with the windows. In October 2023, nearly 1,000 birds died in a single night. The owner finally decided to address the problem head on, installing a pattern of dots on all the glass surrounding the building. The solution cut the number of bird strikes by 95 percent. Awareness about bird safe glass is continuing to grow, and so are the number of solutions. Many glass manufacturers have bird-safe products that work in a similar way. The goal is to break the illusion of glass being a mirror or imperceptible as a solid surface, so most of the fixes involve patterns or designs on the glass. I think it looks pretty cool, actually. And because many bird species can see into the ultraviolet spectrum, you can even get dots and patterns that are practically invisible to humans, but still perceptible to birds to keep them from crashing into windows. Some cities are already including requirements for bird safe glass into codes, particularly in major migration corridors and for buildings that use large, uninterrupted facades of glass. This is a really common design for tall buildings and skyscrapers. Ever since I was a kid, I have always been impressed with this kind of facade. From the outside, it looks like a sleek, continuous column of glass. And it’s pretty interesting how it’s actually done. These are called walls, specifically curtain walls. But they’re also not walls in the traditional sense, at least when it comes to bearing loads. We typically think of a building’s exterior walls as the primary load path - the way forces from the building are transferred to the foundation. With curtain walls, that’s not true, and that name kind of gives it away. In buildings with curtain walls, the load bearing happens through interior columns. The exterior walls just hang there. Not that this needs another analogy, but it’s pretty much like the building is wearing a coat. This has a lot of advantages. A curtain wall is relatively lightweight, reducing structural loads on a building. It’s also thin, maximizing space in a building where it comes at a premium. They’re also unitized: you get very large pieces assembled in a factory so they go up quickly on a construction site. And, of course, you get a lot of light into the building when the entire exterior wall is a window. But how do you hold the glass in place? The process of installing glass, called glazing, is not like installing most other materials. You can’t use traditional fasteners like nails or screws. Glass is brittle, and the sharp point forces would induce too much stress. If you look at the windows of your house, the glass panes are usually sandwiched inside a frame with softer material that both seals against the glass to keep out the weather and spreads out the holding forces across a larger area along the edges of the glass. That’s sometimes called captured glazing. It’s done on large buildings with expansive glass facades too, but it’s not the only way. When you really want the outside of a building to look like only glass with no mullions or framing elements protruding beyond the panes, you can use structural silicone glazing, where the sealant does some or all the work to hold the glass in place. In 4-sided structural glazing, the glass panels are adhesively bonded on all four edges. You have nothing on the exterior except smooth glass. If you’re used to the silicone sealants sold at the hardware store, this might seem absolutely crazy to you. I definitely wouldn’t trust a tube of bathroom caulk to hold thousands of pounds of glass hundreds of feet in the air above sidewalks and roads full of people. To be fair, these systems do usually have some kind of mechanical clips or toggles that surreptitiously prevent panes from coming entirely loose if the sealant fails, but also, structural silicone is very different from caulk. Just to demonstrate this, I have a glass block. First I’m going to attach this to a metal plate using typical silicone caulk you might use in the bathroom. I’m starting with a 45-pound weight on the hook, which is probably a bit ambitious. And of course, the camera died right when that dropped, but it held 45 lbs for just about a minute before it dropped. And part of that’s cause, even after 2 weeks of curing, you can see, only the caulk around the edges actually cured. This stuff is just not designed for heavy weights like this. Now I’ll try it with structural silicone. This stuff comes from a few manufacturers in a variety of strengths, curing systems, and material compatibilities. After I let this cure for a week, which is when the manufacturer says it reaches 50 percent of its strength, I tried my little demo again. Wow. It’s holding 45 pounds just fine. So I added this small metal anvil just for good measure, and it’s still holding fine. Just a silly little experiment like this can give you a lot more confidence that those big insulated glass units on tall buildings aren’t going anywhere. But the engineering of windows doesn’t stop at holding them in place. We also have to think about what happens if they break. The most typical glass we think about with picture frames and windows is actually annealed glass. The manufacturing process is pretty impressive. The molten material is allowed to spread out and float atop a bed of molten tin, making it extremely flat and very consistent in thickness. Then the glass is allowed to cool slowly, which relieves internal stresses. That makes it possible to cut along clean lines and even drill holes in the material. But it also means that when annealed glass breaks, it usually fractures into large, razor-sharp shards that can be extremely dangerous. I think most people have enough experience with the issue that there’s hardly a need at all to say that broken glass is a serious hazard. And in many cases, it’s a simply unacceptable hazard: a slip in the shower that breaks the door, a toddler on a glass tabletop, even pushing too hard on a glass door. There are plenty of documented cases where a simple accident became fatal simply because of how annealed glass becomes jagged and razor-sharp when it fractures. One of the main solutions to the problem is tempering the glass. If you heat glass and cool it down quickly, often using a high-pressure blast of air, you can get the outside to cool a little quicker than the inside of the glass. The outside faces shrink. Then when the inside cools, it shrinks as well, pulling the outside faces of the glass into compression. If you use a polarizing filter, sometimes you can even see the stresses in tempered glass. This is a tricky process because if the cooling happens unevenly, the glass will crack or break. I’ve discovered this myself by accidentally setting a glass dish on the stove burner. But if you do it right, tempering glass makes it much stronger than typical annealed glass. Since the outer faces are in compression, cracks are less able to propagate. But even if it does break, tempered glass has a big advantage. Instead of the large shards, you tiny, relatively harmless pieces. These can still have sharp edges, but just being so much smaller means they’re much less able to injure someone. They have a lot less mass when they fall, and the edges are shorter, so it’s more like angry gravel and less like deadly knives and spears. That’s why tempered glass is often called safety glass, and lots of building codes require it in situations where broken glass can pose a safety hazard like glass doors, large windows close to the ground, and in bathrooms and showers. Most vehicles also use tempered glass on the side windows to reduce the risk of injury during a crash. One disadvantage of tempered glass is that it can’t be modified after the fact. All that built-up stress in the material makes sure it shatters into tiny pieces, but it also prevents you from cutting or drilling holes. Tempering has to be the final step. The other disadvantage also comes from its main advantage. Because tempered glass breaks in a relatively safe way, it doesn’t offer much security. And really it’s true for annealed glass too. Windows aren’t just a thermal weak point in buildings; they are also a security weak point. Why would a criminal struggle to break through a reinforced door if they can just quickly smash a window? That’s where laminated glass comes in. You can glue individual panes of glass together where they still retain almost perfect optical clarity. But even better than that, you can sandwich a tough plastic interlayer between those panes of glass, creating a composite material. And it behaves a lot differently when it breaks. Now you don’t have shards separating at all. Even completely cracked apart, the glass stays adhered to the plastic instead of flying apart. And more importantly, this is still a barrier even after it breaks. I’m not getting my hand through there. Laminated glass is ideal for overhead applications, where a break could otherwise rain down shards on people below. And it’s perfect for commercial buildings, especially on ground floors, to make it more challenging for someone to break in through a window or glass door. Laminated glass is also standard on vehicle windshields to offer more protection from a road hazard that could otherwise break through the glass and injure the driver or passengers. What’s kind of crazy is that I’m just scratching the surface of modern window technology, not to mention the glass itself, which can get a lot more complicated for applications like phone screens. But these are all innovations that are kind of hiding in plain sight, and to me at least, they make the view through a window just a little bit sweeter.

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yesterday • 1 votes
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