Tag: science

Seeing Shapes and Shadows: How Portrait Drawing Changes Our View of Faces | September 12 2025, 15:44

It’s interesting that even a little experience in drawing portraits makes one see patterns in other people’s faces that you wouldn’t think about otherwise. For example, you look at someone’s face, and some points on the face converge into an equilateral triangle. Or the shadow from the sun forms a notable pattern. Or some lines are strictly parallel or perpendicular. And at that moment, you feel like grabbing a pencil and trying to sketch it. At this point, it seems that achieving a likeness is a piece of cake.

Or you notice that a silvery dress is the darkest thing in the picture and probably needs to be depicted almost in black. With highlights, of course. This contradicts the notion that “a silvery dress is just a shiny white.”

Sometimes you look at someone’s face, reassured that the typical proportions are maintained, or, conversely, that they are not. There are also optical illusions. They are the most interesting. It’s when it seems that some point exactly divides a segment in half, but as soon as you measure, it turns out not to be the case.

It’s also interesting that our eyes deceive us about what lines are and what are not lines. Here, it would be more correct not to use the word line” but edge.”

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.

Debunking Kelvin: The Dynamics of Wake Angles at Different Speeds | September 10 2025, 12:03

I look from the boat at the water and wonder whether the divergence angle of the waves depends on speed or not? Started Googling. Turns out, according to Kelvin, it’s constant at any speed, and amounts to 39 degrees (or 19.47 =arcsin(1/3) from the axis). But then I found a paper where the authors studied satellite images and disproved Kelvin, stating that with increasing speed, the wedge indeed narrows slightly (“Ship wakes: Kelvin or Mach angle?”, authors: Marc Rabaud and Frédéric Moisy)

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.

Cracking Codes: Interactive Adventures at the Spy Museum | September 01 2025, 18:15

In the spy museum yesterday, one of the devastatingly informative terminals, where you had to crack the code, allowed you to hack into it too

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”.

Beijing Parade Marks 80 Years Since China’s WWII Victory | August 31 2025, 14:02

On September 3rd in Beijing, a military parade dedicated to the 80th anniversary of China’s victory in World War II will take place. Apparently, I did not pay enough attention during history lessons at school: it turns out that China’s losses during WWII were almost comparable to those of the USSR, considering the official figures (in both cases, they are significantly lower than the actual ones). However, there is a catch – the war between China and Japan began in 1937, and later merged with World War II when Japan attacked the USA and its allies in 1941, officially making China part of the anti-Hitler coalition. Germany in 1937 was just preparing: a year later, in 1938, the Anschluss of Austria began, and another year later (1939) – the invasion of Poland, and at the same time the USSR attacked Finland.

Meanwhile, in Germany, it is considered that the precision of German accounting was incomparably higher, and the cumulative losses of the aggressors, together with Japan, turned out to be four times less than the cumulative losses of the defenders.

The figure of China’s losses mainly consists of civilian population. Their military losses were 3-4 million, while 12-17 million suffered from bombings, punitive actions, diseases (remembering Japanese Unit 731 and biological warfare) and other war consequences.

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Below I quote my post from January 25th of this year – just relevant and timely:

Who won the Second World War? Interestingly, note that no one paid attention to Trump’s words about the Second World War in his recent tweet-ultimatum.

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He writes “Russia helped us win the Second World War” — everyone noted the incorrect figure of 60 million losses, but somehow not this.

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I found an interesting study from 2017. It was a survey (1,338 people) from 11 countries including 8 allied countries and 3 Axis countries.

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It showed significant differences in how the former Soviet Union and 10 other countries remember the war.

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Events marked by representatives of the Soviet Union were almost completely different from those mentioned in other countries. Besides, Russians stated a greater responsibility for the victory in the war (75% of military efforts), than representatives of any other nation (although the USA and Great Britain also estimated their contribution as more than 50%).

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However, when people from each country assessed the contribution of other countries to the war, they attributed a greater role to the USA than to the former Soviet Union.

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An interesting finding is that, when asked why the USA dropped atomic bombs on Japan, most people from ten countries responded that it was to win the war, except for Russians.

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Moreover, the older the respondents were in 7 of these countries, the more often they agreed with the statement that the USA dropped the bombs to end the war.

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Russia (USSR) in the survey results demonstrates a unique narrative centered on the Eastern Front, unlike Western countries.

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Most countries (including former Axis countries) focus on events related to the USA and Great Britain, such as Pearl Harbor, the Normandy landing, the atomic bombings of Japan, and the Holocaust.

USSR holds a central place in the Russian narrative (75% contribution to victory). The USA and Great Britain also overestimate their evaluations, stating their contribution exceeds 50%, focusing on the Western Front and the Pacific Campaign. The total estimates of the contribution of the eight allied countries amount to 309%, showing the effect of “national narcissism”. Most countries prioritize the USA (27%), while the USSR — 20%.

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Four events gained the status of “key” (mentioned by more than 50% of respondents): the attack on Pearl Harbor, the atomic bombings of Japan, the Normandy landing, and the Holocaust. The Russian narrative concentrates on events termed in Soviet and contemporary Russian historiography as the Great Patriotic War (1941–1945). Russians highlighted unique events: battles near Stalingrad, Kursk, Moscow, Berlin, and the blockade of Leningrad. Thus, although the USA and Russia fought together as allies, research shows that there is almost no overlap in which events are remembered as most important. Members of each group mainly remembered those events related to their own country. However, this is not surprising.

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On the subject of atomic bombings, most respondents believe that the purpose of the bombings was to end the war. Russians see this event as an act of intimidating the USSR. Opinions within countries vary by age: older generations are more likely to support the official version of ending the war.

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In France in 1945, 57% of the population considered the USSR the main victor. By 2004, this figure had dropped to 20%, while the share of the USA increased to 58%.

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The reasons are clear: history textbooks and popular culture reinforce national emphasis. In the USA and Great Britain, films and books praising their role in the war predominate. The USSR and the USA fought on different fronts and represent different ideological systems, which determined the narratives. And of course, all countries overstate their role in historical events.

Aladdin’s Chinese Roots and the French Connection | August 30 2025, 11:39

In the original tale of “One Thousand and One Nights,” Aladdin is a boy who lives with his mother in China (!). It is often emphasized that the story takes place in China, but the names of the characters are still Arab. Some believe that Aladdin is Chinese, although of course nationalities did not exist back then.

Moreover, it’s generally complicated with where the tale originates. In “1000 and One Night” (or Arabian Nights) Aladdin was added by the French translator Antoine Galland, who was told the tale by “Maronite Hanna from Aleppo” Hanna Diyab, even the date from the diaries is known – May 5, 1709. Over the course of a month, Diyab told him fifteen more tales. Ten of these, including “Ali Baba,” were later published in the last four volumes of Galland’s “Nights” (1712–1717). Thus, “1000 and One Night” was written by a French translator based on motifs from various places.

Writes twenty-year-old Diyab, the one who told the translator.

“There was an old man who often visited us. He was in charge of a library of Arab books. He read well in Arabic and translated books from this language into French. At that time, he translated the book Tales of 1001 Nights. This man asked for my help with some issues he did not understand, and I explained them to him. The book was missing several nights, and I told him the stories I knew. Then he supplemented the book with these stories and was very pleased with me.” (MS Sbath 254, f. 128a)