Detecting Faster Than Light Travel By Extraterrestrials

August 4, 2024 by Maya Posch 73 Comments

The idea of traveling faster than the speed of light (FTL) has been a popular idea long before [Alcubierre] came up with the first plausible theoretical underpinnings for such a technology. Yet even if such an FTL drive is possible, it may be hundreds of years before humanity manages to develop its first prototype. This does however not prevent us from for looking for possible FTL drive signatures in the spacetime around us. Such a concept was recently proposed by [Katy Clough] and colleagues in a recent article (Arxiv preprint).

For a friendly but detailed explanation the PBS Space Time video (embedded below) on the paper comes highly recommended. The gotcha with detecting an FTL warp drive is that it is undetectable until it collapses in some fashion. By simulating what this collapse might look like, the researchers were able to speculate about the properties to look for. These include gravitational waves, which would not be detectable by an existing gravitational wave detector like LIGO, but we might be able to build one that can.

Ultimately we’d be acting on conjecture on what a warp bubble would look like and how it would behave when it collapses so we might just as well mistake something far less intelligent for Vulcans passing through our solar system. It might also be our first sign of extraterrestrial life, possibly ogling some primitive civilization on a Class M planet until it’s ready for First Contact.

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Pixel Art And The Myth Of The CRT Effect

August 3, 2024 by Maya Posch 61 Comments

The ‘CRT Effect’ myth says that the reason why pixel art of old games looked so much better is due to the smoothing and blending effects of cathode-ray tube (CRT) displays, which were everywhere until the early 2000s. In fits of mistaken nostalgia this has led both to modern-day extreme cubism pixel art and video game ‘CRT’ filters that respectively fail to approach what pixel art was about, or why old games looked the way they did back with our NES and SNES game consoles. This is a point which [Carl Svensson] vehemently argues from a position of experience, and one which is likely shared by quite a few of our readers.

Although there is some possible color bleed and other artefacts with CRTs due to the shadow mask (or Sony’s Trinitron aperture grille), there was no extreme separation between pixels or massive bleed-over into nearby pixels to create some built-in anti-aliasing as is often claimed unless you were using a very old/cheap or dying CRT TV. Where such effects did happen was mostly in the signal being fed into the CRT, which ranged from the horrid (RF, composite) to the not-so-terrible (S-Video, component) to the sublime (SCART RGB), with RGB video (SCART or VGA) especially busting the CRT effect myth.

Where the pixel art of yester-year shines is in its careful use of dithering and anti-aliasing to work around limited color palettes and other hardware limitations. Although back in the Atari 2600 days this led to the extreme cubism which we’re seeing again in modern ‘retro pixel art’ games, yesterday’s artists worked with the hardware limitations to create stunning works of arts, which looked great on high-end CRTs connected via RGB and decent via composite on the kids’ second-hand 14″ color set with misaligned electron guns.

Taco Bell To Bring Voice AI Ordering To Hundreds Of US Drive-Throughs

August 2, 2024 by Maya Posch 41 Comments

Drive-throughs are a popular feature at fast-food places, where you can get some fast grub without even leaving your car. For the fast-food companies running them they are also a big focus of automation, with the ideal being a voice assistant that can take orders and pass them on to the (still human) staff. This probably in lieu of being able to make customers use the touch screens-equipped order kiosks that are common these days. Pushing for this drive-through automation change is now Taco Bell, or specifically the Yum Brands parent company.

This comes interestingly enough shortly after McDonalds deemed its own drive-through voice assistant to be a failure and removing it. Meanwhile multiple Taco Bell in the US in 13 states and five KFC restaurants in Australia are trialing the system, with results apparently encouraging enough to start expanding it. Company officials are cited as it having ‘improved order accuracy’, ‘decreased wait times’ and ‘increased profits’. Considering the McDonalds experience which was pretty much the exact opposite in all of these categories we will remain with bated breath. Feel free to share your Taco Bell or other Voice AI-enabled drive-through experiences in the comments. Maybe whoever Yum Brands contracted for their voice assistant did a surprisingly decent job, which would be a pleasant change.

Top image: Taco Bell – Vadnais Heights, MN (Credit: Gabriel Vanslette, Wikimedia)

Getting A Laser Eye Injury And How To Avoid It

August 2, 2024 by Maya Posch 28 Comments

Most people love lasers, because they can make cats chase, read music from a shiny disc, etch and cut materials, and be very shiny in Hollywood blockbusters, even when their presence makes zero sense. That said, lasers are also extremely dangerous, as their highly focused nature and wide range of power levels can leave a person dazzled, blinded or dead from direct and indirect exposure. A lapse in laser safety was how [Phil Broughton] ended up with part of his retina forever marked, as he describes his adventures with an overly enthusiastic laser company sales person.

Quanta Ray PRO350 with frequency doubling, emitting a 532nm beam – Sales brochure image from Quanta Ray, unknown date — Quanta Ray PRO350 with frequency doubling, emitting a 532 nm beam – Sales brochure image from Quanta Ray, unknown date

It didn’t take much, just this sales person who made a really poor decision while trying to please some customers and nearly ended with multiple adults, a local school, pilots at a nearby airfield getting their retinas blasted out due to an absolutely harebrained idea to use a fairly high-powered Quanta-Ray Nd:YAG laser on reflective surfaces in the open.

This was in 1999, and fortunately [Phil] only suffered some fairly minor damage to his retina from the laser beam reflection. What happened to the customers (who wore argon laser safety glasses) or the sales critter (who left soon after) is not described, but both may have received some bad news when they had their eyes checked shortly after at the ophthalmologist.

These kind of stories are a stark reminder that laser safety is not optional. Lasers producing a visible (400 – 700 nm) wavelength above Class 2 should only be operated in a fully secured environment, with safety glasses for the appropriate laser wavelength. Class 2 lasers producing a non-visible wavelength can cause permanent damage because the blink reflex of the eye does not offer any protection here.

As even some dodgy laser pointers are being (illegally) sold online are actually Class 2, this should make it clear that laser eye injury can happen to anyone, and it only takes a second to change someone’s life forever.

Illustrative models of collinear ferromagnetism, antiferromagnetism, and altermagnetism in crystal-structure real space and nonrelativistic electronic-structure momentum space. (Credit: Libor Šmejkal et al., Phys. Rev. X, 2022)

Altermagnetism In Manganese Telluride And Others: The Future Of Spintronics?

August 1, 2024 by Maya Posch 5 Comments

Magnetic materials are typically divided into ferromagnetic and antiferromagnetic types, depending on their magnetic moments (electron spins), resulting in either macroscopic (net) magnetism or not. Altermagnetism is however a recently experimentally confirmed third type that as the name suggests alternates effectively between these two states, demonstrating a splitting of the spin energy levels (spin-split band structure). Like antiferromagnets, altermagnets possess a net zero magnetic state due to alternating electron spin, but they differ in that the electronic band structure are not Kramers degenerate, which is the feature that can be tested to confirm altermagnetism. This is the crux of the February 2024 research paper in Nature by [J. Krempaský] and colleagues.

Specifically they were looking for the antiferromagnetic-like vanishing magnetization and ferromagnetic-like strong lifted Kramers spin degeneracy (LKSD) in manganese telluride (MnTe) samples, using photoemission spectroscopy in the UV and soft X-ray spectra. A similar confirmation in RuO2 samples was published in Science Advances by [Olena Fedchenko] and colleagues.

What this discovery and confirmation of altermagnetism means has been covered previously in a range of papers ever since altermagnetism was first proposed in 2019 by [Tomas Jungwirth] et al.. A 2022 paper published in Physical Review X by [Libor Šmejkal] and colleagues details a range of potential applications (section IV), which includes spintronics. Specific applications here include things like memory storage (e.g. GMR), where both ferromagnetic and antiferromagnetics have limitations that altermagnetism could overcome.

Naturally, as a fairly new discovery there is a lot of fundamental research and development left to be done, but there is a good chance that within the near future we will see altermagnetism begin to make a difference in daily life, simply due to how much of a fundamental shift this entails within our fundamental understanding of magnetics.

Heading image: Illustrative models of collinear ferromagnetism, antiferromagnetism, and altermagnetism in crystal-structure real space and nonrelativistic electronic-structure momentum space. (Credit: Libor Šmejkal et al., Phys. Rev. X, 2022)

Programming Ada: Implementing The Lock-Free Ring Buffer

August 1, 2024 by Maya Posch 20 Comments

In the previous article we looked at designing a lock-free ring buffer (LFRB) in Ada, contrasting and comparing it with the C++-based version which it is based on, and highlighting the Ada way of doing things. In this article we’ll cover implementing the LFRB, including the data request task that the LFRB will be using to fill the buffer with. Accompanying the LFRB is a test driver, which will allow us to not only demonstrate the usage of the LFRB, but also to verify the correctness of the code.

This test driver is uncomplicated: in the main task it sets up the LFRB with a 20 byte buffer, after which it begins to read 8 byte sections. This will trigger the LFRB to begin requesting data from the data request task, with this data request task setting an end-of-file (EoF) state after writing 100 bytes. The main task will keep reading 8-byte chunks until the LFRB is empty. It will also compare the read byte values with the expected value, being the value range of 0 to 99.

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A Look Inside The Super Nintendo Cartridges And Video System

July 31, 2024 by Maya Posch 22 Comments

Despite being effectively sold as a toy in the 1990s, the Super Nintendo Entertainment System (SNES) was pretty bleeding-edge as far its computing chops were concerned. This was especially apparent with its cartridges, such as in this excellent summary article by [Fabien Sanglard].

In addition to the mask ROM that stored the game data and (optionally) battery-backed SRAM to store save data, a wide range of enhancement processors existed that upgraded the base SNES system with additional processors for more CPU performance, enhanced graphics and so on. Imagine sticking a game cartridge in a PlayStation 4 today that boosted CPU speed by 5x and gave it a much better GPU, this was the world of SNES games.

On the other side of the video game cartridges was the video output system, which seems easy enough in today’s world of digital HDMI and DisplayPort output. In the 90s video output did however mean NTSC and SECAM/PAL, which means playing nice with frequencies, different resolutions (lines) and squeezing as much as possible into a single frame in a way that works with the game console’s rendering pipeline. As a result of this the PAL version of Super Mario World has a larger vertical resolution than the NTSC version (240 vs 224 lines), even if it’s still squashed into the same 4:3 format. For the physical video output side, European gamers were spoiled with an AV connector to (RGB) SCART output, while the rest of the world dealt with some variety of RF composite or S-video.

Although the SNES’s successor in the form of the N64 would not take cartridges to the same extremes, it was this flexible architecture that gave the SNES such an amazing game library.