crypto newb here. i’m not trying to be sarcastic. bitcoin has been around for years, but i still can not wrap my head around its value as a currency. there is the trading aspect, some have made millions and some have lost millions. but outside the trading sphere, what value does it have? how long is it actually going to be around? and what about all the shitcoins? are they NFTs all over again? the best i can understand it, is that it is like kohl’s cash, only traded in one venue. what am i missing? submitted by /u/No_Type1123 [link] [Kommentare]

Hello all, I am trying to recreate this mechanism as a personal project - and I am really having trouble wrapping my head around how it works. The knees and below make perfect sense, but the hips are throwing me off. What is the purpose of the 2 perpendicular motors at the top? The ones facing horizontally? And how does the rest of the hip fit in with that purpose? I hope this question makes sense. Here is a research paper showing another angle and a more mechanical breakdown. https://arxiv.org/html/2512.16705v1#S4.F3 Also Nvidia GTC 2026 is where the original clip is from (2:11:36) further in the video it shows a side view: https://www.nvidia.com/gtc/keynote/ submitted by /u/halxcyion [link] [Kommentare]

My dad emigrated from Colombia to North America when he was 18 looking looking for a better life. For my brother and I that meant a lot of standing outside in the cold. My dad’s preferred method of improving his lot was improving lots, and my brother and I were “voluntarily” recruited to help working on the buildings we owned. That’s how I came to spend a substantial part of my teenage years replacing fences, digging trenches, and building flooring and sheds. And if there’s one thing I’ve learned from all this building, it’s that reality has a surprising amount of detail. This turns out to explain why its so easy for people to end up intellectually stuck. Even when they’re literally the best in the world in their field. Consider building some basement stairs for a moment. Stairs seem pretty simple at first, and at a high level they are simple, just two long, wide parallel boards (2” x 12” x 16’), some boards for the stairs and an angle bracket on each side to hold up each stair. But as you actually start building you’ll find there’s a surprising amount of nuance. The first thing you’ll notice is that there are actually quite a few subtasks. Even at a high level, you have to cut both ends of the 2x12s at the correct angles; then screw in some u-brackets to the main floor to hold the stairs in place; then screw in the 2x12s into the u-brackets; then attach the angle brackets for the stairs; then screw in the stairs. Next you’ll notice that each of those steps above decomposes into several steps, some of which have some tricky details to them due to the properties of the materials and task and the limitations of yourself and your tools. The first problem you’ll encounter is that cutting your 2x12s to the right angle is a bit complicated because there’s no obvious way to trace the correct angles. You can either get creative (there is a way to trace it), or you can bust out your trig book and figure out how to calculate the angle and position of the cuts. You’ll probably also want to look up what are reasonable angles for stairs. What looks reasonable when you’re cutting and what feels safe can be different. Also, you’re probably going to want to attach a guide for your circular saw when cutting the angle on the 2x12s because the cut has to be pretty straight. When you’re ready to you will quickly find that getting the stair boards at all the same angle is non-trivial. You’re going to need something that can give you an angle to the main board very consistently. Once you have that, and you’ve drawn your lines, you may be dismayed to discover that your straight looking board is not that straight. Lumber warps after it’s made because it was cut when it was new and wet and now it’s dryer, so no lumber is perfectly straight. Once you’ve gone back to the lumber store and gotten some straighter 2x12s and redrawn your lines, you can start screwing in your brackets. Now you’ll learn that despite starting aligned with the lines you drew, after screwing them in, your angle brackets are no longer quite straight because the screws didn’t go in quite straight and now they tightly secure the bracket at the wrong angle. You can fix that by drilling guide holes first. Also you’ll have to move them an inch or so because it’s more or less impossible to get a screw to go in differently than it did the first time in the same hole. Now you’re finally ready to screw in the stair boards. If your screws are longer than 2”, you’ll need different ones, otherwise they will poke out the top of the board and stab you in the foot. At every step and every level there’s an abundance of detail with material consequences. It’s tempting to think ‘So what?’ and dismiss these details as incidental or specific to stair carpentry. And they are specific to stair carpentry; that’s what makes them details. But the existence of a surprising number of meaningful details is not specific to stairs. Surprising detail is a near universal property of getting up close and personal with reality. You can see this everywhere if you look. For example, you’ve probably had the experience of doing something for the first time, maybe growing vegetables or using a Haskell package for the first time, and being frustrated by how many annoying snags there were. Then you got more practice and then you told yourself ‘man, it was so simple all along, I don’t know why I had so much trouble’. We run into a fundamental property of the universe and mistake it for a personal failing. If you’re a programmer, you might think that the fiddliness of programming is a special feature of programming, but really it’s that everything is fiddly, but you only notice the fiddliness when you’re new, and in programming you do new things more often. You might think the fiddly detailiness of things is limited to human centric domains, and that physics itself is simple and elegant. That’s true in some sense – the physical laws themselves tend to be quite simple – but the manifestation of those laws is often complex and counterintuitive. Consider the boiling of water. That’s straightforward, water boils at 100 °C, right? Well the stairs seemed simple too, so let’s double check. Put yourself in the shoes of someone at the start of the 1800’s, with only a crude, unmarked mercury thermometer, trying to figure the physics of temperature. Go to your stove, put some water in a pot, start heating some water, and pay attention as it heats. The first thing you’ll probably notice is a lot of small bubbles gathering on the surface of the pot. Is that boiling? The water’s not that hot yet; you can still even stick your finger in. Then the bubbles will appear faster and start rising, but they somehow seem ‘unboiling’. Then you’ll start to see little bubble storms in patches, and you start to hear a hissing noise. Is that Boiling? Sort of? It doesn’t really look like boiling. The bubble storms grow larger and start releasing bigger bubbles. Eventually the bubbles get big and the surface of the water grows turbulent as the bubbles begin to make it to the surface. Finally we seem to have reached real boiling. I guess this is the boiling point? That seems kind of weird, what were the things that happened earlier if not boiling. To make matters worse, if you’d used a glass pot instead of a metal one, the water would boil at a higher temperature. If you cleaned the glass vessel with sulfuric acid, to remove any residue, you’d find that you can heat water substantially more before it boils and when it does boil it boils in little explosions of boiling and the temperature fluctuates unstably. Worse still, if you trap a drop of water between two other liquids and heat it, you can raise the temperature to at least 300 °C with nothing happening. That kind of makes a mockery of the statement ‘water boils at 100 °C’. It turns out that ‘boiling’ is a lot more complicated than you thought. This surprising amount of detail is is not limited to “human” or “complicated” domains, it is a near universal property of everything from space travel to sewing, to your internal experience of your own mind. Again, you might think ‘So what? I guess things are complicated but I can just notice the details as I run into them; no need to think specifically about this’. And if you are doing things that are relatively simple, things that humanity has been doing for a long time, this is often true. But if you’re trying to do difficult things, things which are not known to be possible, it is not true. The more difficult your mission, the more details there will be that are critical to understand for success. You might hope that these surprising details are irrelevant to your mission, but not so. Some of them will end up being key. Wood’s tendency to warp means it’s more accurate to trace a cut than to calculate its length and angle. The possibility of superheating liquids means it’s important to use a packed bed when boiling liquids in industrial processes lest your process be highly inefficient and unpredictable. The massive difference in weight between a rocket full of fuel and an empty one means that a reusable rocket can’t hover if it can’t throttle down to a very small fraction of its original thrust, which in turn means it must plan its trajectory very precisely to achieve 0 velocity at exactly the moment it reaches the ground. You might also hope that the important details will be obvious when you run into them, but not so. Such details aren’t automatically visible, even when you’re directly running up against them. Things can just seem messy and noisy instead. ‘Spirit’ thermometers, made using brandy and other liquors, were in common use in the early days of thermometry. They were even considered as a potential standard fluid for thermometers. It wasn’t until the careful work of Swiss physicist Jean-André De Luc in the 18th century that physicists realized that alcohol thermometers are highly nonlinear and highly variable depending on concentration, which is in turn hard to measure. You’ve probably also had experiences where you were trying to do something and growing increasingly frustrated because it wasn’t working, and then finally, after some time you realize that your solution method can’t possibly work. Another way to see that noticing the right details is hard, is that different people end up noticing different details. My brother and I once built a set of stairs for the garage with my dad, and we ran into the problem of determining where to cut the long boards so they lie at the correct angle. After struggling with the problem for a while (and I do mean struggling, a 16’ long board is heavy), we got to arguing. I remembered from trig that we could figure out angle so I wanted to go dig up my textbook and think about it. My dad said, ‘no, no, no, let’s just trace it’, insisting that we could figure out how to do it. I kept arguing because I thought I was right. I felt really annoyed with him and he was annoyed with me. In retrospect, I think I saw the fundamental difficulty in what we were doing and I don’t think he appreciated it (look at the stairs picture and see if you can figure it out), he just heard ‘let’s draw some diagrams and compute the angle’ and didn’t think that was the solution, and if he had appreciated the thing that I saw I think he would have been more open to drawing some diagrams. But at the same time, he also understood that diagrams and math don’t account for the shape of the wood, which I did not appreciate. If we had been able to get these points across, we could have come to consensus. Drawing a diagram was probably a good idea, but computing the angle was probably not. Instead we stayed annoyed at each other for the next 3 hours. Before you’ve noticed important details they are, of course, basically invisible. It’s hard to put your attention on them because you don’t even know what you’re looking for. But after you see them they quickly become so integrated into your intuitive models of the world that they become essentially transparent. Do you remember the insights that were crucial in learning to ride a bike or drive? How about the details and insights you have that led you to be good at the things you’re good at? This means it’s really easy to get stuck. Stuck in your current way of seeing and thinking about things. Frames are made out of the details that seem important to you. The important details you haven’t noticed are invisible to you, and the details you have noticed seem completely obvious and you see right through them. This all makes makes it difficult to imagine how you could be missing something important. That’s why if you ask an anti-climate change person (or a climate scientist) “what could convince you you were wrong?” you’ll likely get back an answer like “if it turned out all the data on my side was faked” or some other extremely strong requirement for evidence rather than “I would start doubting if I noticed numerous important mistakes in the details my side’s data and my colleagues didn’t want to talk about it”. The second case is much more likely than the first, but you’ll never see it if you’re not paying close attention. If you’re trying to do impossible things, this effect should chill you to your bones. It means you could be intellectually stuck right at this very moment, with the evidence right in front of your face and you just can’t see it. This problem is not easy to fix, but it’s not impossible either. I’ve mostly fixed it for myself. The direction for improvement is clear: seek detail you would not normally notice about the world. When you go for a walk, notice the unexpected detail in a flower or what the seams in the road imply about how the road was built. When you talk to someone who is smart but just seems so wrong, figure out what details seem important to them and why. In your work, notice how that meeting actually wouldn’t have accomplished much if Sarah hadn’t pointed out that one thing. As you learn, notice which details actually change how you think. If you wish to not get stuck, seek to perceive what you have not yet perceived.

I built a 10-inch mini rack from aluminium extrusions and I had a lot of fun doing it. I want to share my build in this post. In January of 2025, Jeff Geerling released a video about 10-inch mini racks. I was absolutely oblivious to this new trend, and I instantly knew that I wanted to build one for myself some day, although I didn't have a real use for one. That said, I've been working on a virtualization project recently and I've bought six 1L PC's (three for each simulated datacenter). Because these 1L PCs are small, they have huge external power bricks. As these mini PCs are also connected to two networks, they create a huge mess on my desk. Finally a reason to build a mini rack, to tidy things up! There are a few different brands of mini rack for sale, but I wanted to make one for myself. Prebuilt racks (kits) are not cheap for what they are so I wanted to try and see if I could build one myself for less money. Turns out you can buy 20mm aluminium extrusions and accompanying components to build your own rack. (Aluminium extrusions have a standardized 'groove') Aluminium extrusions are bars with a groove on all four sides. These bars have a standard format and you can slide all kinds of equipment in there and lock it in place with set screws. It seems to be used a lot for home made 3D printers, CNC machines and whatnot. In the picture above a special corner piece is used to connect three bars together, fixed in place with set screws. The L-brackets can be used to create T-sections within a frame to sturdy the structure and provide additional mounting points. In my rack, the middle post carries the back of the shelves holding the mini PCs. These sliding cage nuts (M5) can be used to attach anything anywhere. In this example we used four of them to hold the side panels in place. These cage nuts can also be used for their intended purpose: mount 10 inch rack-mount equipment. In this picture below, some cage nuts are left that hold the side panel in place. Also notice in the upper left that I've used cage nuts to attach some black cable tie holders that in turn keep cables in place. The computer trays I planned on ordering 10 inch 1U shelves and be done with it. Unfortunately these metal shelves are too expensive for my taste and would have cost more than the aluminium frame including components (I need 8 shelves). Many 10-inch rack builds - such as the ones featured by Jeff Geerling - use 3D-printed face plates to mount various kinds of equipment. Jeff showcased some of these models in separate videos. That said, I decided against using 3D printed shelves. First of all, I don't have a 3D printer and as useful as 3D printing can be, I feel that 3D printers often turn plastic into landfill. I'd probably feel differently if (more) sustainable materials would have been used1. So instead, I chose to order cut-to-size aluminium sheets and I used the L-brackets to hold them in place. The aluminium shelves turned out OK, but they are not ideal. The 1mm thick plates do bend slightly under the weight of the computers, although it's still fine. Aligning the four L-brackets on the same horizontal plane was a pain. Filing off the sharp corners of each plate was no fun, I should have ordered them with rounded corners. I think these aluminium plates create an open design that is better for keeping the machines cool. There are many 10-inch self 3D models available for these 1L PCs but they all create a tight collar around the front bezel of the computer, which looks amazing, but I don't think it's great for airflow. Regular metal shelves would also have been fine. 10 inch power distribution As you can see below, the backside shows the internals of the case are a bit of a mess2. The truth is that I've should made the rack at least 1U higher to accommodate the very lengthy cabling of the power bricks. All the cabling does fit, but it's not easy to make it clean looking and also give the power bricks - which lie at the bottom - some airflow. No price for cabling management and neatness, that's for sure I've used two 10-inch rack mount power distribution units from Brenenstuhl. They were cheap but they unfortunately didn't fit in a horizontal position. The PDUs are the only actual 10-inch rack-mount component in the entire build and the fact that they didn't fit felt ironic. The cause is simple: in a 19-inch or 10-inch rack, the square holes holding the cage nuts are 'flat sheets', so the power cable sticking out of the side of the PDU can flow behind those square holes. If you use the 20mm aluminum extrusions, there is a 20mm bar in the way. This is why I had to mount the PDUs vertically, which did work fine. At the top, the PDUs are kept in place with another L-bracket clamping the PDUs firm against the rail. The external power bricks of the 1L PCs' are a huge pain. Having six cords and external adapters was absolutely no option for me, I wanted a fully self-contained rack. If you ever build your own rack, try to use computers that have a power supply build-in. I wish I could power these 1L PCs with a 'power shelf'. In this case, a power supply with enough capacity to sustain these PCs at the required voltage and with the proper brand-correct power jack, maybe like this. Cooling All power sockets are in use by the six 1L PCs and the two network switches, so how are we going to power the two cooling fans3? Fortunately there exist USB-to-fan-header cables. It feels dirty but it isn't. USB is only 5 volt but these adapters contain a boost converter that outputs 12 volt for the fans. The power draw of these fans (around 1W) is well below the threshold of 4.5W for a USB3 port. The open backside probably doesn't help with cooling and Ideally I'd fill in the gaps. Due the the irregular shapes, I feel it's too much effort. I do feel a proper airflow at the front of the 1L PCs, so I think it's 'certified good enough4'. Networking The 1L PCs have two network connections, one to each switch. The 3Com switch at the top is 1 Gbit, the TRENDnet switch is 2.5 Gbit. I used the Conceptroning ABBY12G USB3-to-2.5Gbe adapter to connect the 1L PCs to the switch. The 2.5 Gigabit network is a backend network for live migration of virtual machines amongst other traffic. I'm able to achieve line-speed with both iperf3 and virtual machine migrations. The gigabit 3com switch is at least 26, maybe 27 years old! The rack has become a bit crowded due to all this network connectivity, as seen on earlier pictures. It didn't help that I ordered short UTP cables that are quite stiff. Panels The side panels are sheets of anodized aluminium which look good, in my opinion. I forgot to order panels for the top and bottom. Therefore, I decided to go with some wood panels instead of aluminium sheet metal. A local shop offers scrap wood for peanuts and also cuts it to size for a 'few peanuts more'. Very handy if you don't have the right equipment to make straight, clean cuts of wood. Although not pictured, the bottom panel is kept in place with screws locking into cage nuts. These screws also hold the rubber feet in place. Problems A lack of access to the VGA/DP ports: If I lock myself out of a machine, I need to remove one or more fans and connect a VGA/DP cable to the back of the affected machine. This also means moving a lot of UTP cables to the side. I can attach a keyboard to the front but attaching a monitor is thus a real pain. In more regular rack builds, you can add 'keystones' that extend ports to a panel on the outside of the case, where you can connect to an interface without any issue. Cost Item Total Aluminium sheets 82.95 € Aluminium extrusions 26.22 € Rack mount small items 79.96 € wood 7 € shipping costs (over all orders) 20 € USB to 2x 4-pin fan header 12 € 10 Inch PDU 2x 43 € Network cables 42.15 € Total Price 313.28 € All prices include 21% Dutch sales tax. The total price excludes the two Noctua fans, which would probably add another 40 euros. The price is a bit inflated because I overbought small items for rack building. If I opted for wood paneling instead of aluminum panels, that would probably also cut the paneling cost in half. How I use this mini rack The mini PCs are running Debian and they all act as virtualization hosts, using KVM. The gigabit ports are used for the management and provisioning network (PXE+TFTP+iPXE+HTTP). The 2.5Gbit network is used for virtual machine migration and a VXLAN network that encapsulates all the different virtual machine networks. By default, this rack is off. When I want to use it, I turn on a Zigbee power adapter and after a delay, wake-on-lan packets are sent to all six machines to power them on. Power consumption The two switches, two fans and six 1L PCs together use around ~90W idle. Evaluation I'm quite happy with this build. Cost was acceptable, I think it looks decent enough and it really cleans up my desk. Although cable management is clearly not my strong suit, I feel it's an overall improvement. Maybe a few handles for carrying would be a nice future addition, but for now this rack is finished. Did I save any money? I'm not so sure. Acknowledgements Jeff Geerling for introducing me to 10 inch racks This build by Logan Marchione inspired me to further look into aluminium extrusions If you feel differently about 3D printing that's OK. I'm not looking for a discussion or argument about the topic, I'm only stating my motivations. ↩ it's so, so much cleaner than the mess of wires on my desk. I'm already happy with this improvement. ↩ The fans I used are of different size and type, in part because it's what I had lying around. ↩ https://www.youtube.com/SuperfastMatt ↩ Solar Status 71 TiB NAS Projects fio-plot Showtools Storage Fan Control Grafana Dasboard for storage metrics Categories Apple Development Hardware Infrastructure IT Linux Networking Projects Security Solar Storage Uncategorized ZFS Archive 2026 2025 2024 2023 2022 2021 2020 2019 2018 2017 2016 2015 2014 2013 2012 2011 2010 2009 2008

Apple AirDrop and Google/Samsung Quick Share are proximity file-transfer protocols used by over five billion devices, yet their application-layer security properties remain largely unstudied because both stacks are proprietary and undocumented. Both protocols are reachable from wireless proximity without any prior pairing and process complex serialized content (binary plists, CPIO archives, Protocol Buffers, UKEY2 handshakes) inside privileged daemons, making them attractive zero-click targets across multiple operating systems. We perform the first cross-platform reverse engineering and protocol-aware fuzzing study of both stacks. We reconstruct AirDrop's seven-layer state machine and DVZip adaptive compression from binary analysis, build AIRFUZZ, a protocol-aware fuzzer that mutates pre-compression representations, and complement it with targeted hand-written analyses of Samsung's Quick Share service and Google's Quick Share for Windows. We discover six vulnerabilities (V1-V6): three pre-authentication issues in macOS/iOS AirDrop (V1: Swift fatalError DoS in the HTTP path router; V2: unbounded XML plist recursion in Foundation; V3: NULL dereference in Network.framework's HTTP/1.1 parser), two protocol-layer flaws in Samsung Quick Share (V4: pre-authentication OfflineFrame dispatch; V5: D2D encryption bypass for three frame types), and a heap use-after-free in Google Quick Share for Windows (V6) for which Google awarded a bounty. We responsibly disclosed all findings, and Apple, Samsung, and Google have acknowledged the reports.

A longform writing social network where each user has exactly one post.

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In economic terms AI will make super intelligence a factor of production.

Fill out your own 2026 World Cup bracket — group winners, the best third-placed teams, and every knockout tie to the final — then see what the crowd predicts.

Meta’s built facial recognition into its smart glasses. Northeastern researchers explain why regulations around this are dangerously behind.