Tag: Engineering

Solar Simplicity: How Turkey’s Homes Heat Water with the Sun | September 11 2025, 06:44

I constantly see such panels on almost every house in Turkey. Of course, my first thought was that these were solar photovoltaic panels for generating electricity. But the second thought — they are expensive, there shouldn’t be so many of them, plus typically just two panels on a roof seems too few. I started googling.

It turned out, these are solar water heaters, more precisely, flat-plate solar collectors. The system is simple, reliable, and inexpensive — that’s why they are installed on every other house.

The principle of operation: the panels consist of an absorber (usually copper or aluminum plates with a black coating), a transparent cover (low-iron glass for greenhouse effect), and thermal insulation (glass wool or stone wool). A heat-carrying fluid circulates in the tubes — either water or antifreeze (glycol).

Solar rays heat the absorber up to 60-90°C, the heat transfers to the fluid, which by the principle of thermosiphon (natural convection, without a pump) rises to the tank, which is usually nearby. The tank is a thermos of 100-300 liters, with insulation, so the water stays hot for 2-3 days.

This too was a surprise. I actually thought the tanks were just metal and heated up in the sun by themselves. That’s how it was in Baku. It turns out, no, and so they are white here, not black.

In Turkey, with over 2000+ hours of sunshine a year, such a system covers 70-90% of the hot water needs for a home. The efficiency of the collector is 40-60% (depending on the model and angle of installation, optimally 30-45° to the horizon for the latitude of Antalya). For a family, this costs from 500-1500 euros, with a payback period of 3-5 years due to savings on gas/electricity. Electricity is expensive in Turkey. Plus, government subsidies and tax incentives encourage installation.

Probably, there are also electric panels, but I haven’t seen them yet.

Exploring Airport Security: How Baggage Scanners Work | September 02 2025, 20:29

The day after tomorrow, I am flying to Amsterdam (and then to Turkey), and I remembered that I had an unanswered question to myself about how baggage scanners work at the airport. Of course, I knew that it was essentially computer tomography, X-rays and all that, but I wanted more details. And below is the response as to why they ask you to take out water, and why sometimes they do not.

It turns out that modern scanners can not only see the shape of objects but also determine what material they are made of. How does a regular scanner work? Dense materials (such as metal) absorb a lot of radiation and appear bright or opaque in images. Less dense materials absorb little radiation and appear dark. Hence laptops, for example, had to be taken out — not because the scanner couldn’t recognize them, but because their dense components (battery, boards) could be used to hide other prohibited items behind them. So, it has long been not just scanners, but computer tomography — in essence, the bag or suitcase is scanned from all sides, then a 3D image is created. It seems like everyone knows this.

But I mentioned that they understand the materials items are made from. How?

It turns out that the scanner uses dual-energy X-ray technology. It scans the object with two beams of rays of different energy levels (high and low). Since materials absorb radiation differently depending on the energy of the ray and their atomic composition, the system analyzes this difference. Based on the absorption ratio of the two beams, the effective atomic number Z — a key characteristic, a kind of “elemental fingerprint” of the substance, is calculated.

The problem is that this “fingerprint” of water (~7.4) and many explosives are almost identical. This is precisely why water was banned. Relying only on this parameter would mean receiving a huge number of false alarms.

Here is where computer tomography (CT) comes into play. The scanner creates an accurate three-dimensional (3D) model of the contents of the bag. From the 3D model, the system obtains the exact volume (V) of each object. Based on data on the absorption of X-rays, its mass (m) is calculated. Then it’s simple: ρ=m/V.

That is, the system does not make a decision based on one parameter. It plots each detected substance on a two-dimensional graph with axes “Z — density.” On this graph, water and explosives, having almost the same atomic number, occupy completely different positions due to different densities.

And that’s precisely why water can sometimes be carried through. Smart machines simply do not mark it as something significant, but still identify it as water. Then procedures follow. If the airport has updated the machines, but not the procedures, they will ask to dispose of the water. But also, not all machines are updated everywhere, and at the same airport, it depends on which line is open at the moment.

The cost of such a scanner is $300-400 thousand.

The scanners for people work differently. They use millimeter waves. They pass through clothing and reflect back from the skin. Water absorbs them significantly, so they penetrate only a couple of millimeters. The system registers the reflected signal and constructs a three-dimensional map of the body surface and objects under the clothing. But it does not show this — instead, it displays a simplified contour of a person and shows on it what ML found unusual. Therefore, by the way, many try to carry various items inside themselves, knowing that such a scanner absolutely cannot see it.

Echoes of Anthrax: The Amerithrax Investigation Unveiled | September 02 2025, 13:33

From the museum of the day before yesterday. Probably, some of you remember the notorious case in 2001: shortly after the 9/11 attacks, the USA experienced a series of bioterror attacks: someone mailed letters containing powder with anthrax spores (Bacillus anthracis). This led to the deaths of 5 people and infected 17, but it could have ended much worse for the entire planet. The investigation, known as “Amerithrax,” was conducted by the FBI in collaboration with other agencies and became one of the most complex in history.

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For those who might not know — the inhalational form of anthrax has a mortality rate of 85–90% without treatment. Symptoms appear after 6 days, by which time dozens will be infected. It can’t be destroyed — spores remain viable for decades in the soil. For example, on the Scottish island of Gruinard, they lingered for nearly 50 years after wartime testing. Only after 50 years had passed and after 280 tons of formaldehyde solution had been sprayed across all 196 hectares of the island, and the most contaminated topsoil around the dispersal site had been removed, did the island become relatively safe. Thus, anthrax could easily be more terrifying than a global nuclear war.

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So, returning to the subject. Initially, suspicions fell on various individuals, including Iraq or Al-Qaeda, but no evidence was found.

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The key breakthrough was scientific examination. Scientists analyzed the anthrax strain from the letters — it was the Ames strain used in American laboratories. Using microbial forensics (genetic analysis), they identified unique mutations in the spores that narrowed the source down to flask RMR-1029 in the USAMRIID (United States Army Medical Research Institute of Infectious Diseases) laboratory at Fort Detrick, Maryland.

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In other words, every living being has names and genealogy from birth, it’s just a matter of willingness to dig into the genealogy. Apparently, controlled substances have their own registry office, so to speak.

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Bruce Ivins, a microbiologist who worked there, was the custodian of this flask and had direct access (although more than 100 others did as well).

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Later, investigators gathered circumstantial evidence. Ivins had been working late at the lab just before the mailings in September and October 2001, which was inconsistent with his usual schedule. He could not convincingly explain these hours. Moreover, in early September 2001, he was vaccinated against anthrax, which seemed suspicious. The FBI also accused him of attempting to mislead the investigation: he allegedly provided false anthrax samples to divert suspicion and attempted to frame colleagues. In 2001, Ivins sent an email to colleagues offering the Ames strain for analysis, which might have been an attempt to cover his tracks.

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Behavioral signs also played a role. Ivins suffered from depression and suicidal thoughts, especially after another suspect (Steven Hatfill) was cleared in 2008. In June 2008, he was hospitalized in a psychiatric clinic, where during therapy, he made statements that the FBI interpreted as “denials without denial” — for example, that he “had no heart for killing” and did not remember participating in the attacks.

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By 2008, the investigation had narrowed down to Ivins. When he learned that charges were being prepared against him, on July 29, 2008, he took a lethal dose of Tylenol (acetaminophen). Formal charges were never brought. In 2010, the FBI officially closed the case, declaring Ivins the sole perpetrator.

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However, the conclusions remain controversial: the US National Academy of Sciences noted in 2011 that the genetic examination was not convincing enough for a definitive conclusion, and some microbiologists, victims’ families, and politicians demanded further investigation. As of now, no new discoveries have been made, and the case is considered closed.

The Ingenious Spy Device Gifted in Friendship: Unveiling The Thing | September 01 2025, 01:03

Today in the museum I saw The Thing in person – simply a brilliant espionage device. In 1945, a group of Soviet schoolchildren presented a large wooden Great Seal of the United States to the U.S. Ambassador in Moscow, Averell Harriman, as a “gesture of friendship”. The seal was beautifully hand-carved and hung in the ambassador’s office for a whole 7 years. And it leaked secrets!

No batteries involved! It was all very clever, especially for 1945.

Essentially, it was a passive radio relay or “parasitic resonator”. Inside the wooden seal was a small metal cylinder with a membrane and an antenna-rod.

Soviet operators directed a specific frequency radio wave (about 330 MHz) into the ambassador’s office.

Inside the device was a cavity resonator, tuned to the same frequency. It “responded” to the radio signal and began to retransmit it back.

On one side of the cylinder was a thin flexible membrane. It vibrated from the sound in the room (voices, footsteps).

The vibrations of the membrane altered the capacity and resonance parameters of the device, slightly shifting the reflected radio signal by frequency and phase. This was the modulation of speech onto the external signal.

Outside the building (like in a KGB car nearby), the retransmitted signal was received and the sound modulation was extracted – effectively capturing the overheard conversation.

Why was this almost impossible to detect? The device had no battery and emitted nothing by itself. It “came to life” only when irradiated with an external radio signal. In standard radio monitoring checks, it remained “dead”. Essentially, it was akin to an ancestor of the RFID tag – a passive device that operates only on external request.

But most interestingly, the inventor was Leon Theremin, the same person behind the musical instrument “thereminvox” (played with hands in the air).

His biography reads like a novel. In the early 1920s, Theremin went to the U.S., patented his thereminvox instrument, and collaborated with RCA; his New York studio was visited by Charlie Chaplin, Albert Einstein, Gershwin, and other notable personalities. It is written that he visited the USSR – Already in 1926, he demonstrated television at the Kremlin.

At that time, televisions with screens the size of a matchbox were being created, but his television had a huge screen (1.5 x 1.5 m) and a resolution of 100 lines. In 1927, the scientist demonstrated his installation to Soviet military leaders K.E. Voroshilov, I.V. Tukhachevsky, and S.M. Budyonny:

state minds watched in horror as Stalin walked through the Kremlin courtyard on the screen.

This sight so frightened them that the invention was immediately classified and quietly buried in the archives, and television was soon invented by the Americans.

Eventually, in 1938, he secretly returned to the USSR, but was soon arrested as a “non-returnee” and sent to the camps, but his talent was still used in the so-called “sharashka” – on projects together with Sergei Korolev, including the development of radio-controlled apparatuses and listening systems, including the aforementioned “Great Seal bug”.

Exploring the Boundless Spectrum: The World of Animal Hearing | August 29 2025, 17:56

From my notes as I read Ed Yong’s Immense World—

“..It is known that the range of audible frequencies for animals is different from that of humans, but I didn’t realize just how different. Imagine the highest pitch in the world—it would be just under 20 kHz, as it’s considered the upper limit of the audible range. Both the upper and lower limits tend to decrease with age. Most adults can’t hear sounds over 16 kHz. Anything above 20 kHz we call ultrasound.

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So, it turns out that our closest relatives, chimpanzees, can hear up to 30 kHz, dogs up to 45 kHz, cats up to 85 kHz, mice up to 100 kHz, and moths even up to 300 kHz. Imagine, there are so many high-frequency sounds around us, and how rich their sound world is compared to our limited one. It would be interesting to wear headphones that compress the range from 20-40000 Hz to 20-15000 Hz. Many animals, such as mice, actively use ultrasound for internal communication, beyond the hearing range of their predators.

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And when the topic of ultrasound comes up, it’s impossible not to mention bats with their echolocation. Turns out, it’s a wildly interesting topic.”

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Probably everyone knows that bats successfully hunt in caves, where no light penetrates at all, and they don’t crash into stalactites and stalagmites. There’s an English saying, blind as a bat, but actually, they can see. Some species see better, others worse. But let’s talk about echolocation.

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In general, it’s just radar. The bat screams, the sound bounces off a tree, comes back into its ears, and it gets information about how far away the tree is and whether to slow down or not. But the devil, as they say, is in the details. “Engineering” ones.

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Firstly, high-frequency sound attenuates quickly, so you need to shout very loudly for something to bounce back from a few meters away. Beyond that, bats simply don’t “see.” So, they do indeed shout very loudly, and it’s a directed scream. Specifically, they measured 138 decibels, the sound level of a jet engine if you stand next to it. But in the ultrasonic range.

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Secondly, when they scream so loudly, they need to plug their own ears so as not to kill their sensitive apparatus. It turned out that they have special muscles that block the inner ear during the scream.

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Thirdly, both they and their prey are on the move, very fast and erratic. Meanwhile, the speed of sound is about 343 meters per second. The bat’s brain must calculate the difference between the signal and the echo, taking into account both its own movement through space and the movement of the prey. It turned out that the bat’s vocal muscles can contract up to 200 times a second. Moreover, the frequency depends on the phase of the hunt. 200 times—that’s the final phase, when the moth is right in front of the nose, and tiny movements need to be tracked.

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Fourthly, the bat’s brain also has to cope with creating interference between what was shouted out two moments ago and what was shouted out a moment ago. Considering that the sound can echo off the far wall and the near branch. Plus there are waves from the cries of other bats, and they’re usually very numerous in caves. To manage this, they seem to throw a bit different modulation, plus this musculature allows them to “fire” very short pulses—a few milliseconds—and to renew pulses at their own frequency through very short intervals. Imagine what kind of computer in their brains performs the inverse Fourier transform.”

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So, all this works pretty well in small groups. But for example, the Brazilian free-tailed bats live in groups of millions. Really, together 20 million mouths shout something and wait for their echo from the walls and each other. You can’t just pick modulation and frequencies that easily, but somehow they manage. Not perfectly, and if they gather in a really big bunch in the cave, then they perform their commute to the hunt and back to the cave “by memory” – probably due to issues with echolocation. When a “door” was placed at the entrance to the cave, a bunch of bats crashed into it.

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Fifth, consider how they determine distance. It’s necessary to calculate the difference between the signal sent and the signal received (amid a bunch of noise from other bats), and for hunting, it needs to be calculated very precisely. And sound of course isn’t light, but 343 meters per second is also a lot. So studies have shown that bats can recognize differences as little as 1-2 millionths of a second, which allows them to determine distance to fractions of a millimeter. In other words, our eyes are significantly less accurate than their ears.

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Plus, a moth is actually a fairly complex 3D creation that reflects sound differently with its different parts. Otherwise, bats would eat everything that moves. They recognize. In complete darkness. A mouse’s scream contains a whole palette of frequencies, which reflect differently off parts of a moth, and the mouse’s brain somehow manages to translate this into a coherent picture. Moreover, for each of the constituent frequencies, the delay will be its own.

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Then, all this information is layered over time. Roughly speaking, a snapshot from one point is combined with a snapshot from a point a half meter to the right, then from a point half a meter forward, and so on many, many times, which enhances “sharpness” and detail. Overall, it’s the same with us – we only see the spot in front of us clearly while the rest is constructed by the brain. But the brain of a bat weighs 1-2 grams against our half kilogram.

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Think about it, you’re flying with such a built-in radar, and in front of you are two branches at the same distance, which produce essentially the same echo for their ears. And to distinguish them and understand that it’s not one object but two, you really need an advanced brain.

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So, they send pulses lasting 1-20 ms, plus longer pauses between pulses. The pulses are complex in terms of frequencies, so such bats are called frequency modulation (FM) bats. But there are about 160 species that have a much longer cry—many tens of milliseconds but with short pauses, and instead of a complex gamma of frequencies, these use a pure “note.” These bats are called CF—constant frequency. So here’s the thing with these bats—there’s a problem with the Doppler effect, which is an increase in frequency as the distance decreases. Since their brain is tuned to a strict frequency, like 87 kHz for example, they might lose their prey if the echo that reaches their ears is shifted in frequency. And what they do—they shout at a sound speed lower, so that after the Doppler effect it arrives at the correct frequency for the brain.”

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Incidentally, their radar has two modes—forward and downward, the echoes from which are processed separately. The downward radar provides information about position in space, and the forward radar—about the position in space of the prey.

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When I researched the subject, I found that yes, after 20 kHz humans hear nothing, with one exception—frequencies of 2.4 GHz and 10 GHz, which actually belong to the microwave range. Yes, humans can “hear” these frequencies, but not with the ear, but “hear.” This phenomenon is called the microwave auditory effect or the Frey effect. Initially, this effect was registered by people working near radars during World War II, and the sounds they perceived were not heard by others. It turned out that when pulsed or modulated microwave radiation was applied to areas around the cochlea, it was absorbed by the tissues of the inner ear, accompanied by their thermal expansion. In the course of this process, shockwaves are produced, perceived by humans as sound, which no one else hears. It was also discovered that with the appropriate choice of the modulating signal, it is possible to transmit information to a person in the form of individual words, phrases, and other sounds. Depending on the radiation parameters, the sound created in the head can be irritating, cause nausea, and even disable. The volume of the perceived sound can be changed, but acoustic trauma is not possible, as the eardrum does not participate in the process at all. Generally speaking, the method of specifically transmitting sonic messages that are absolutely inaudible to others opens up a whole bouquet of possibilities. I wonder if research is still being conducted on this topic. Google shows that they used to be pretty intense.”

I once published this along with a video, and Facebook reckons that if you publish a video, the text should be one, at most two lines. And in the end, almost no one saw this text. Everyone just watched the video of a bat flying around my apartment 🙂

Cycling for History: A Book and An Unexpected Glimpse into 1930s Migration Trends | August 24 2025, 18:27

I couldn’t resist and bought the book Great Depression in Perceville, VA, where I arrived by bike. I still don’t know how to carry it back for an hour in cycling clothing without a backpack. Interesting note on a random page

Translation:

AMTORG RECEIVES 100,000 APPLICATIONS FOR 6,000 QUALIFIED JOBS IN RUSSIA

(Business Week, October 7, 1931, pp. 32–33)

NEW YORKERS make up the bulk of Americans who have decided, at least for now, to tie their fates with the Russians. Pennsylvania, New Jersey, and Illinois contribute the highest number of applications for the new call for “6,000 qualified workers,” with Michigan, Ohio, California, and Massachusetts also being well represented.

The “Amtorg” office in New York received over 100,000 applications for these 6,000 job slots. Just one morning alone saw 280 applications. All states except ten were represented. Alaska and Panama also contributed one applicant each, and 18 Canadians wanted “to try their luck in Russia.”

Industrial states, naturally, provided the largest number of applications, but others were represented as well. Iowa, Texas, and Idaho also contributed some number of qualified workers.

Since it is widely known that Russia is “industrializing,” most applicants are skilled workers in machinery, railroads, metallurgy, automotive manufacturing, or the construction industry. A look at the qualifications of 280 applicants from one “typical” morning showed that specialists of all professions were looking for work, even if it meant moving to Russia and being paid in rubles. Among them were: 2 hairdressers, 1 funeral director, 2 plumbers, 5 painters, 2 cooks, 36 “clerical” workers, 1 lathe operator, 9 carpenters, 1 aviator, 58 engineers, 14 electricians, 5 salespeople, 2 printers, 2 chemists, 1 shoemaker, 1 librarian, 2 teachers, 1 cleaner and dyer, 11 auto mechanics, 1 dentist.

About 85% of the applicants are U.S. citizens, only 40% of whom were born in the country. 60% of the foreigners primarily come from Eastern Europe. A few African Americans applied, but their numbers are small, as most of them are unskilled workers.

Women constitute only a small portion of applicants, although many wives decided to accompany their husbands in this endeavor. Most workers applying are married and have children.

Three main reasons for wanting to get a placement are named: (1) unemployment; (2) dissatisfaction with conditions here; (3) interest in the Soviet experiment. Almost all foreign workers declare that they do not intend to stay in the USSR. Among engineers, only 10-20% plan to stay.

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This is 1931, one of the most challenging years of that period. Somewhere in the mid-thirties, it started to improve, and it must be said, WWII ultimately defeated it.

Inside Apple AirPods: Design, Battery, and Antenna Secrets Revealed | August 23 2025, 01:52

Very interesting video about how Apple Airpods headphones work (in the comments). You can read about it, or you can just like this post and go check out the original video in the comments. It has pictures!

Battery. 6 hours of operation, but the capacity is only 2% of the iPhone battery capacity. “Dead zones” in the battery, which lead to reduced operating time, can occur due to sudden temperature changes or even just dropping the headphones on the floor. There is a very dense “layered cake” made from a couple dozen layers of anode-cathode. Batteries of fake AirPods or cheap analogs are much worse. Physics: Poor packaging means less active material and fewer lithium ions moving with each cycle => reduced energy density and increased internal resistance => more energy is lost as heat => battery wears out faster.

Antenna. It is located in the stem because the human head significantly dampens the signal. But there is little space in the stem. Metal strip antenna, size 2 mm by 10 microns(!). That’s thinner than human hair. At such size, it cannot maintain shape on its own. In other consumer electronics, antennas can be etched on the printed circuit board, but this limits them to two dimensions. For the AirPod stem, there isn’t enough space. Therefore, Apple uses a clever solution. They embedded the antenna in the surface of a molded plastic cylindrical part. There, clever conductive plastic is used, with added metal. A laser engraves the exact shape of the antenna in the form of small channels with a rough surface. Then, this groove is subjected to electroplating, first with copper, then covered with gold to protect against corrosion. As a result, a durable conductive track is formed, which matches the 3D geometry of the molded part, which would be impossible to create using traditional machining methods. The plastic not only structurally supports the antenna. Other components are attached to it, such as the cable wrapping around the stem to connect the antenna to the Bluetooth chip, the pressure sensor in the stem.

Microphone. In AirPods, not electret microphones, but MEMS: a microelectronic” version of the condenser type. Well, actually, this is not only Apple – any modern TWS headphones, unless they are the cheapest ones. That is to say, modern microphones are made using the same technology as types – photolithography, layer by layer, only in this case it’s a mechanical device, with calculated cavities and flexible layers. Separately interesting is how they make the cavities – they make holes through which etching solution penetrates inside and dissolves the sacrificial layers of silicon dioxide.

Because of such microscopic size, there are several microphones. But why more than one microphone is needed? At the bottom of the AirPods, you will see a small mesh that allows air to enter the second microphone. When you talk, your voice reaches both microphones, but not at the same time. With a difference of only a few millimeters, the chip can detect a delay of six microseconds between when your voice reaches each microphone. This is enough to determine where the sound is coming from and focus on it. Since it precisely knows the distance the microphones are from one another, the chip can compare each signal and amplify your voice during calls.

The third microphone is for noise cancellation. It is located right in front of the speaker, inside your ear.

The microphones consume about 130 mA, which would quickly drain the battery if they were always active. That’s why they are only turned on when you make a call or use noise cancellation. But AirPods are always waiting for a Siri request. How is this possible without constantly active microphones? Here’s a clever solution. Inside the part that is in your ear, there is a small sensor—an accelerometer. It’s the same type of sensor used in phones to determine orientation. But here it serves a different purpose. Instead of measuring orientation, it senses vibration. When you talk, your voice moves through your jawbone. And this vibration is detected by the accelerometer. This low-power consumption signal is enough to wake up the system and activate the microphones when it senses you want to activate Siri. Imagine that, eh?

The sound in AirPods is tuned not “by ear,” but based on a scientific model of the “ideal sound” (Harman curve), which describes the combination of frequencies most people find most pleasing. For this, there is a complicated system of calculated vents and meshes — to control the air flow, which prevents the occurrence of unpleasant “humming” or sharp sounds inside the ear canal. The larger the cells — more air passes through, smaller — less. Such is the mesh, visible as black things on the white earphone—I thought it was for beauty. No, this is exactly that mesh. But at the same time, some kind of moisture protection must be made, and here the mesh is porous. It is claimed that there is some sort of nano-coating that repels water.

Bluetooth. Why it is so immune to interference. Turns out, it uses frequency-hopping spread spectrum technology (Frequency Hopping). Bluetooth devices quickly switch between different channels many times a second and adapt accordingly.

Exploring TestMySearch.com’s Virtual Shopper System | August 15 2025, 04:27

As part of the TestMySearch.com project, I am creating a “virtual shopper” system that simulates the behavior of a real user in an online store: it starts with an abstract goal (for example, “something bright and sexy for the gym”), turns it into a specific search query, performs the search on the site, and depending on the results, may either continue browsing or, with a certain probability, reformulate the query if the findings do not match the original goal; the system then evaluates the pages for their alignment with the initial idea, opens product cards, randomly changes parameters such as color or size, makes decisions about adding to the cart and placing an order, and may also leave the site, which allows generating many sessions similar to real ones overnight for testing search, filters, and recommendations even before live users arrive.

The system is fully automatic. That is, the browser in the video opens by itself, the search field appears by itself (i.e., independent of the site), the system itself concocts the text based on that very initial goal, then the facets and search results are displayed, which may also be in a form unpredictable to the system — but it still understands what is what, and makes decisions about whether to rephrase the query, select a facet or click on a search result. There is a certain probability that the virtual user will leave the site. If the query is reformulated, for example, this virtual user does not repeat queries that have already led to empty or irrelevant results, so within the session there is “memory”.

Aluminum: From Precious Metal to Everyday Marvel | August 03 2025, 01:09

The USA imports aluminum mainly from Canada because aluminum leaves Canada and arrives in the USA. And from Europe, it would be alumin𝒊um!

Also, sapphires and rubies are essentially rusty aluminum, where in the process the new material becomes much harder than the original. In interaction with oxygen, different varieties of the mineral corundum are formed, which chemically is crystalline aluminum oxide (formula Al₂O₃). And bulletproof glass is essentially transparent rusty aluminum, aluminum oxide, but with aluminum nitride.

Also, aluminum was the most valuable metal on Earth until the 20th century. When Napoleon III entertained guests, they ate with golden spoons, while he used an aluminum one. And the “cap” of our Washington Monument is made of aluminum for that very reason.

Seattle’s Monorail: A Vintage Transport Still in Motion | July 22 2025, 16:28

Seattle’s two-station monorail (a world record!), reportedly self-sustaining and extremely popular among tourists despite being arguably the city’s most pointless form of transportation, features the same Alweg trains that have been in operation since its inauguration 63 years ago for the World Fair.

Interestingly, even the one-station monorail has a driver. I recently saw a job posting for a Monorail Driver, paying $20/hour (with a minimum wage of $18.67). Roughly the same hourly rate can be earned by stocking shelves in any supermarket in the USA.

However, the only major accident on the Seattle monorail in 2005 was due to a driver’s error. According to authorities, the driver of a train heading into the city failed to yield to another train at a spot where the tracks are too close together for simultaneous passage.

The problem was that the tracks were installed without the gap necessary for the free passage of trains. Imagine that! At one spot, just so:) This was deliberately designed to allow loading ramps to extend beyond the carriages. For 40 years, careful attention ensured that trains never traveled simultaneously on this section. But then one day, a driver decided to leave early — and the rest is history. As always, Murphy’s Law applies.

Nearby in 1988, the construction of the Westlake Center mall uncovered an issue just days before its scheduled opening. Engineers found the west track was two inches (50 mm) closer to the platform and building than it should have been, making it impossible to use. The issue came to light when a retractable loading ramp at the terminal scratched the blue train during a trial run; the misalignment was caused by a pin in a hinge that did not fold properly. The ramp was repaired in November, but other technical issues and prolonged safety inspections delayed the new terminal’s opening by four months. To avoid redesign, trains were simply not allowed to run simultaneously. As of 2025, bi-directional movement is still NOT anticipated above the narrow gauge section at the southern (Westlake) station:-)

By the way, exactly a month ago, the monorail at VDNKh in Moscow, opened 21 years ago, was permanently closed. There, too, nobody understood its purpose, and moreover, it was brutally unprofitable.

In the photo, Nadia enjoys Seattle