In the picture – Cherenkov radiation. This is me in 2009 at the Chernobyl Nuclear Power Plant, standing in the hall with the nuclear reactor. The water in the photo is for slowing down neutrons and cooling spent fuel rods. The glow occurs when electrons are ejected from the fuel at a speed exceeding the phase velocity of light in water. Kind of like a sound barrier, but for light. The intensity of this glow can roughly indicate how “fresh” the fuel is in the pool. The brighter and denser the blue, the more active the decay processes are. Interestingly, Cherenkov radiation is the reason why there is no absolute darkness at great depths of the ocean floor.
On the anniversary of Chernobyl. Those interested in this topic may not know that a similar accident could have occurred ten years earlier on the main (very first RBMK-1000 unit) Leningrad Nuclear Power Plant.
There was a nearly identical situation: one turbine in operation, reactor shutdown by emergency protection, and subsequent power escalation.
Back then, the situation was saved by the Chief Reactor Operator Mikhail
Karrask, who, acting intuitively and relying on his experience with industrial reactors, introduced into the reactor in portions
12 manual control rods
BEFORE pressing the emergency shutdown button.
A couple of years ago, Karrask passed away. This story is almost unknown outside the industry. For proof, google his obituary on Rosatom.
The technical part. The main danger of the RBMK reactors at that time was in the design of the control rods. At the bottom, they were equipped with graphite “displacers”. When the emergency shutdown button was pressed, the rods began moving down, and in the first seconds, the graphite tips did not dampen the reactor, but on the contrary, displaced the water and increased the power in the lower part of the active zone. But precisely, the instructions in case of trouble suggested pressing the emergency shutdown button. If you followed the instructions, “Chernobyl” would have happened earlier.
After the incident at the Leningrad NPP, a commission was formed. Experts (including those from the Kurchatov Institute of Atomic Energy) pointed out the dangerous design flaws of the RBMK – the positive void coefficient of reactivity and incorrect design of the rods. Unfortunately, extensive changes to the design of all RBMK reactors were not made at that time. Only operational regulations recommendations were given, which, as history showed, were insufficient to prevent the tragedy in Chernobyl.
essentially, a person in space is about these days and about the days 50 years ago. The International Space Station is already kindergarten: in terms of the Earth, it is only slightly higher than airplanes fly.
We had a thunderstorm last night. The whole county is buzzing because everyone thinks that something exploded just before midnight. Several posts in a row on social media. In short, it was thunder. But a bit more rare than usual. Caused by a 401 kA lightning, dubbed the Wild House Shaker. A typical lightning strike is 30 kA. If the numbers are to be believed, 401 kA is really damn a lot. They will likely say we haven’t had such lightning here for decades.
Attaching an interesting map.
The points on the map show superbolts — lightning strikes with an energy of no less than 1M J. Red points — particularly powerful superbolts with an energy of more than 2M J. That is, superbolts mostly occur in the northeastern part of the Atlantic and in the Mediterranean Sea, and less frequently — in the Andes, off the coast of Japan, and near South Africa.
this is what the page from which I took the map says (translation):
“New work shows that superbolts most often occur over the Mediterranean Sea, the northeastern Atlantic, and over the Andes, as well as in smaller amounts to the east of Japan, in tropical oceans, and near the southern tip of Africa. Unlike regular lightning, superbolts often strike over water.
“Ninety percent of lightning occurs over land,” said Holzworth (that’s the main guy on lightning at the University of Washington).
“But superbolts mostly arise over water, right up to the coastline. For example, in the northeastern Atlantic, the distribution maps of superbolts clearly show the outlines of the coasts of Spain and England.”
“The average energy of a discharge over water is higher than over land—that we knew,” he said. “But we did not expect such a stark difference.”
The season for superbolts also does not match the usual patterns of lightning. Regular lightning most often occurs in the summer—the three main so-called “lightning chimneys” coincide with summer thunderstorms over America, Africa south of the Sahara, and Southeast Asia. However, superbolts, which are more common in the Northern Hemisphere, occur in both hemispheres from November to February.
The reason for such a distribution remains a mystery. In some years, there are significantly more superbolts than in others: the end of 2013 was record-breaking, and the end of 2014 was the second largest, while in other years such events were much less frequent.
“We speculate that this may be related to sunspots or cosmic rays, but we will leave that for future research,” said Holzworth.
“For now, we are just demonstrating that there is a previously unknown pattern.”
An interesting philosophical thought came to my mind. What if evolution doesn’t exist in us (not in biological life), but in our system of understanding the laws of the world 🙂 That is, the system of understanding the laws of the world adapts itself so that everything more or less matches up. That is, the brain constructs an internal hallucination and constantly suppresses it in order to minimize the error of prediction. And there’s a big question — does our understanding system strive for truth (absolute correspondence to the world) or just for comfort (so that the picture in the head does not fall apart)?
With this approach, there’s a problem that if you don’t look into the future, then at each iteration, the understanding system adjusts its model so that the prediction works, but simultaneously creates problems for the next iteration, because it has to account for them already. As a result, this layered pie accumulates contradictions and constraints to such an extent that each subsequent theory becomes more and more complex and accreted with a multitude of unexplainable gaps. Dark matter, black hole radiation, gravitational waves, and so forth appear to somehow stretch the owl to fit the globe.
But yes, this is related to the question of whether mathematics was discovered or invented.
The spokesperson for the Phystech press service explains how to determine cardinal directions in Moscow when navigation systems are down. Find the North Star or use the sun: it rises in the east and sets in the west. Also reminds us how to determine directions using trees. Ziya, do you know how to find cardinal directions using trees? — What’s there to know? Fir tree points north, palm tree points south!
Overall, it seems the Phystech press service is not aware that in Moscow, the annual amplitude of sunrise point movement is almost 90 degrees. That means, it only sometimes (like now, in March) actually coincides with the east. But they do know the word “asterism”. I think most readers will place it somewhere near the word “flatulence”
It turns out that π² ≈ g is not some mystical coincidence. When the first scientists contemplated the definition of the meter, there was one elegant proposal: to make the meter equal to the length of a pendulum that takes exactly one second to swing from one side to the other.
For a mathematical pendulum, the period of oscillation is calculated by the formula: T = 2π √(L / g). If we take the length L = 1 meter and set the full period T = 2 seconds (so that it takes exactly one second for each half swing), the equation implies: g = π² (m/s²).
The definition of the meter was later changed: it was tied to one ten-millionth of the distance from the equator to the North Pole along the meridian passing through Paris. However, this geodetic definition was inspired by the earlier idea with the pendulum. Notably, both approaches match up with an accuracy of 1%. Essentially, since the old “pendulum” definition was the main candidate for a long time, values were adjusted so that the new meter was convenient and close to the measurements customary at that time.
It is also interesting that the number of seconds in a year roughly corresponds to the number of pi * 10^7. Earth’s orbital speed is about v = 30 km/s. The distance from the Sun to Earth is approximately r = 150,000,000 km. Thus, over a year, Earth travels a path of about d = 2 * π * r. Then, the orbital period equals T = d/v = π * 2 * r/v = π * 10⁷ seconds.
Walking with Yuki, I see across the sky a very distinct and narrow streak clearly (apparently, an airplane had passed by), and usually a contrail disappears quite quickly, but today it is unusually sharp and long.
I started to investigate and it turns out this is a reliable indicator of changing weather, specifically the arrival of snow or rain: as we are actually expecting a sudden knee-deep snowfall tomorrow. In short: the airplane trail acts as an indicator of humidity at high altitudes.
Here’s how it works:
For a contrail not to evaporate but to start “smearing”, the air at an altitude of 8–10 kilometers must be very humid (saturated with moisture). If the air is dry, the ice crystals from the engine quickly turn into invisible vapor (sublimate). If the air is moist, the crystals have nowhere to evaporate. Instead, they start attracting extra moisture from the surrounding environment and grow. High humidity at high altitudes is a sure sign of an approaching warm atmospheric front.
Today I was surprised to learn that the Coriolis force is pronounced as CoriolIs force, not coriOlis force as we were taught in school. I started to investigate what else was wrong, and discovered something amazing.
It turns out what we called Gay-Lussac’s law is known as Charles’s Law in the rest of the world, and what we called Charles’s Law is known throughout the world as Gay-Lussac’s Law.
The Cartesian coordinate system here is Carthesian. Cartesius is just the Latinized name of René Descartes.
In our textbooks, the law of conservation of mass is called the Lomonosov-Lavoisier Law (what enters the chemical reaction = mass of the substances formed). In the rest of the world, it is exclusively the Law of Lavoisier (Lavoisier’s Law). Lomonosov got included here only because “whatever is taken from one body is added to another”.
Also, it turns out that if you have to explain Pythagoras’ theorem to someone in English, without a hint, it’s absolutely impossible to guess that it’s Pythagoras. Greek names are generally a mess. Thales here is pronounced as Teelis.
For some reason, in physics Roentgen is called RentgEnom, although it’s Röntgen with the emphasis on ö.
In Russia, a trapezoid is a quadrilateral with two sides parallel and two not. In the USA, our trapezoid is known as Trapezoid, and the word Trapezium here refers to a quadrilateral with no parallel sides at all. In the UK, it’s the opposite. Our trapezoid is Trapezium, and the “skewed” quadrilateral is Trapezoid.
Hi, I'm Rauf Aliev. 