Month: January 2024

I am thoroughly enjoying Ed Yong’s book An Immense World, which explores how living creatures perceive the world. There’s a really interesting chapter on electroreception. I need this to better understand—it’s wildly interesting, and for you—I don’t know why you need it 🙂 but it’s really interesting, hit like if you agree it’s interesting.

Well, everyone probably knows about the electric eel, which with its electric organs can create a potential difference (voltage) of up to 860 V and a current strength of up to 40 mA—enough to lay down a horse. Literally, this was tested on horses in 1880 by Alexander von Humboldt, ending up with dead horses.

But the most interesting thing is not that they are just swimming batteries. It’s interesting that many animals have electroreception—they can sense their immediate surroundings just as a theremin does. Since electroreception requires a conductive environment, these are all aquatic creatures—catfish, mormyrids, notopterids and gymnotids. Specifically, the last group includes eels and knifefish. The Black Ghost or Knifefish—a popular aquarium fish—generates a small voltage, but not to kill, rather to “see” with its entire body and see through sand and objects.

This feature is called active electrolocation. Both weakly and strongly electric fish create around themselves a characteristic dipole electric field. If there are no objects in the water around the dipole, it is symmetrical. Its configuration depends on the water conductivity and distortions when an object with different conductivity from water enters the electric field. In other words, by using its electric field (generated by discharges) and electroreceptors, the fish feels disturbances in the field when something enters it. An electric potential redistribution occurs on the surface of the body, which helps them determine the direction of impact or “invasion,” the size of the object, etc. The black knifefish has 14000 electroreceptors distributed over its body. The organ of electroreception consists of specialized spinal nerves that are spontaneously activated and are the fastest firing cells known in the nervous system of any animal—they continuously produce electrical signals at a rate of more than 2000 times per second.

Considering that the speed of electromagnetic waves in water reaches 225,000 km/s, electroreception allows weakly and strongly electric fish to almost instantaneously react to field distortion (by fleeing or attacking), while signals from other sensory systems may be delayed in time. Unlike the ultrasound of bats, which I wrote about in the last post, here the electric fields do not move. Moreover, the fish can change the intensity of the electric field to enhance sensitivity and distance. Yes, it does take their energy, so they do it when necessary.

There were experiments when a knifefish distinguished a sealed opaque pot from another similar one by their contents.

It gets even more interesting. Since they can sense each other’s fields, they have adapted to use these fields for communication. Unlike everything else, radio communication is the most reliable, and here it’s essentially radio. The only problem is distance, but compared with the size of the fish, it’s still decent. Experiments show that electric fish are sensitive to changes in the field with a resolution of 1/1000000 second. They themselves emit signals with a resolution of about 1/2000 second.

Some species of fish can pulse their fields specifically for communication, and the shape of this pulsation—the duration and how the voltage changes over time—contains information about what kind of fish, sex, status, and sometimes identity. But timing—that is, a larger form determining rhythm, regularity, etc.—determines the essence of the message. There are “words” in this language that mean “let’s hurry,” and others about love.

For example, as I mentioned earlier, research by neurobiologist Ted Bullock has shown that the electrical field of the black knifefish pulses every 0.001 second, deviating by no more than 0.00000014 second. In other words, these are the most accurate biological clocks in the animal kingdom. If you attach a clock to the fish, it would be off by an hour per year. Moreover, the fish’s “radio” uses frequency modulation (FM) to transmit messages.

It turns out that electroreception is not only present in electric fish, but also in many others in the water. For example, sharks. They have special organs on their noses called the ampullae of Lorenzini. This allows them to capture electric fields and detect extremely small changes in their intensity. These organs got their name because in 1678, this doctor wrote “what the hell is on their noses,” and a biologist R.W.Murray answered him only 300 years later, but by then these things had already been named.

So, with these ampullae of Lorenzini organs, sharks and rays feel living beings, even if they are not visible—for example, when the prey is hiding in the sand. But how, sharks can’t generate a field, unlike the knifefish or eel? Therefore, this is called passive electroreception. All living beings generate microvoltages, and the shark’s organs feel this at a short distance. This discovery is already 50 years old, but for some reason they didn’t tell us such interesting things at school. For example, hammerhead sharks can detect an electric field of 1 nanovolt (1/1000000000 volt) per centimeter of water.

Among a large group of mammals, electroreception is known only in the Australian platypus and is suspected in the echidna. The platypus has 50000 receptors, and by the same principle as the shark, searches for food in murky water or on the bottom under sand. Besides everything else, its eyes, ears, and nose are closed under water, so it uses only electroreception. There was also an interesting experiment with bees. If you look at their world through organs of electroreception, there would be an entire universe. For example, flowers have a negative charge, bees—a positive (because they lose electrons in flight), and according to the experiment, bees can distinguish artificial flowers with different charges. Bees don’t have any ampullae of Lorenzini, but they do have sensitive hairs on their skin.

Sometimes you wonder how skillfully nature uses the laws of physics.

A very interesting description of the solution from Alexander Zhadan on how he searched for a wife using ChatGPT. He claims that he eventually proposed to a girl who, as stated, ChatGPT communicated on his behalf for a year. For this purpose, as reported, the neural network interacted with another 5200 girls, filtering out those deemed unnecessary and focused on one.

Alexander describes what’s under the hood of the system:

・GPT-4 API

・Google Chrome up to version 115

・Several hundred lines of Python with Selenium, Chrome Driver, FlutterFlow, LangChain, Torchvision

・Telegram API

・VPN

・Proxy

・Loads and loads of prompts

The prompt at the beginning of the acquaintance: You write that you liked the photos of a girl you are meeting. The acquaintance occurs in my name [specify]. You maintain the dialogue, ask questions

How GPT-4, as an acquaintance, communicates upon request: you write politely and simply to a girl named [specify] to communicate in the role of [specify]. You are busy and won’t be able to talk soon, but you keep the dialogue minorly active. To the girl, you are an acquaintance who establishes the relationship at this level. Only you know this and always write your request considering it

The history of creation and jokes are detailed in the thread – link to the long thread X with diagrams, codes, block —

. I can’t judge how truthful it all is, but I’d hire the dude as an architect even if it’s 100% fiction. Technically, everything is feasible, but it requires a lot of work to do it alone

A minute of English. Today I learned what a Suicide Run is.

Nadya was talking about her coaching routine, and I discovered for myself that it’s an interval exercise where you have to run to a certain point, then return, then run to the next, farther point, and return again. And it turns out there is also a Russian Twist. This is an exercise for the oblique abdominal muscles, performed by sitting on the floor, leaning back and rotating the torso from side to side.

Recently, I came across an interesting expression in a book: “to face plant.” It means to smash your face into something.

There’s also an interesting phrase “throw someone under the bus.” This expression is often used in situations where one person puts another in a disadvantageous position or blames them for something, to improve their own situation or reputation.

I don’t get it, why isn’t parallel export working? I want to watch the new Master and Margarita.

Reading and getting stunned. Here’s an update to my previous post about bats. So, it is known that they hunt nocturnal moths and butterflies, what in Russian is called “moth”. And a moth, as we have all seen many times, like butterflies, has scales on its wings, making it so terry. By the way, the structure of these scales creates colors through interference and diffraction, the pigments of which are completely absent in the insect, like blue.

It turns out that these scales are not just there but serve as protection against bats. Firstly, they absorb ultrasonic waves and reflect back a small part, which partially hides the insect from the “radar”.

Moreover, half of the scale-winged creatures have ears, which detect the bat much earlier than it can “see” them with its radar. And they make a getaway sooner.

But there’s an even cooler tool in the tiger moth. It has a mechanism that jams the radar. Special hammers, which it uses to create ultrasonic disturbances and confuse the bat. Experiments were conducted playing recordings, and the bats “broke down”. Whereas the Luna Moth doesn’t have these hammers, nor does it have ears or even a mouth, but with its tail, they create an echo, which also confuses the bat. An experiment was conducted with a moth with a damaged tail – it was eaten instantly, while healthy ones manage to disturb the bat’s flight so they don’t get caught. It’s definitely the tail doing it, but the physics of it all remains a mystery.

Check out the first post if you haven’t already

My IntelliJ Idea is tired

Continuing to read Ed Yong’s Immense World. As always, sharing something interesting. THIS IS A LONG READ! For me — to research further, for you — I don’t know why you need this. But it will definitely be interesting.

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 imaginable – it would be just below 20kHz, as it is considered to be the upper limit of hearing. Both the upper and the lower limits tend to decrease with age. Most adults cannot hear sounds above 16 kHz. Anything over 20kHz we call ultrasound.

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

And of course, when it comes to ultrasound, one cannot overlook bats with their echolocation. It turned out to be wildly interesting.

Probably, everyone knows that bats successfully hunt in caves where no light penetrates, and they don’t crash into various stalactites and stalagmites. There’s a saying in English, blind as a bat, but in fact, bats do have vision. Some species have better, others worse. But let’s talk about echolocation.

In general, it’s just like radar. A bat screams, the sound bounces off a tree, returns to its ears, and it gets the information on how far away the tree is, and whether to stop or not. But, as they say, the devil is in the details. “Engineering” details.

Firstly, high-frequency sound attenuates quickly, so you need to scream very loudly for something to return from a distance of several meters. Beyond that, bats simply can’t “see”. So indeed, they scream very loudly and in a directed manner. Specifically, they’ve recorded at 138 decibels, which is the sound level of a jet engine if standing nearby. But in the ultrasonic range.

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

Thirdly, they and their prey are actually moving very quickly and chaotically. Meanwhile, the speed of sound is about 343 meters per second. The bat’s brain must calculate the difference between the signal and the response, taking into account both its own motion in space and that of the prey. It was found that the vocal muscles of a bat can contract up to 200 times per second. Moreover, the frequency depends on the phase of hunting. 200 times – that’s the final phase, when the moth is right in front of them, and minor movements need to be tracked.

Fourthly, the bat’s brain also has to cope with not creating interference between what was screamed two moments ago and what was just screamed a moment ago. Considering that sound may reflect off a far wall and a nearby branch. Plus, there are waves from the screams of other bats, usually a lot in caves. For this, they seemingly throw slightly different modulations, plus their muscular system lets them “fire” very short pulses – a few milliseconds, and renew the pulses with their own frequency through very short intervals. Just think what kind of computer in their brains performs the inverse Fourier transform.

In conclusion, all this works rather well in small groups. But for example, Brazilian free-tailed bats live in groups of millions. Really, together 20 million mouths scream and wait for their echo from walls and each other. You just can’t pick modulation and frequencies simply, but they somehow manage. Not perfectly, and when they gather in really large numbers in a cave, their commuting to hunt and back in the cave is done “by memory” – presumably due to difficulties with echolocation. When a “door” was placed at the entrance to the cave, a bunch of bats smashed into it.

Fifthly, think about how they measure distance. You have to recalculate the difference between the sent signal and received one (amid a bunch of noise from other bats), and to hunt, this needs to be very accurately calculated. Of course, sound isn’t light, but 343 meters per second is still a lot. So, studies have shown that bats can recognize differences within millionths of a second, allowing them to determine distance in fractions of a millimeter. In other words, our eyes are much less precise than their ears.

Additionally, a typical moth is quite a complex 3D creature, which reflects sound differently with its various parts. Otherwise, bats would eat everything that moves. They discriminate. In complete darkness. A mouse’s scream contains a whole palette of frequencies, which reflect differently off parts of the moth, and the bat’s brain somehow manages to translate all this into a coherent picture. Moreover, for each of the constituent frequencies, the delay is different.

Then all this information is layered over time. Roughly speaking, a snapshot from one point combines with a snapshot from half a meter to the right, then half a meter forward and so on, many times, thereby “sharpness” and detail are enhanced. 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 bat’s brain weighs 1-2 grams compared to our half kilogram.

Now, think about it, flying with such a built-in radar, and in front of you are two branches at the same distance, which essentially produce the same response for their ears. To distinguish them and understand that it’s not one object but two requires a really advanced brain.

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 where the scream lasts significantly longer – tens of milliseconds, but with short pauses, and instead of a complex range of frequencies, these use a pure “note”. Such bats are called CF – constant frequency. So, these bats have a problem with the Doppler effect – the increase in frequency as distance decreases. Since their brain is tuned to a strict frequency, say 87kHz for example, they might lose their prey if they receive a response shifted in frequency. And what they do – they scream at a sound speed lower, so that it ends up at the right frequency in the brain as a result of the Doppler effect.

Interestingly, their radar has two modes – forward and down, the replies from both are processed separately. The downward radar gives information about the position in space, while the forward radar gives the position in space of the prey.

In my research, I found that yes, after 20kHz humans hear nothing except for one exception — frequencies 2.4GHz and 10GHz, which belong to the microwave range. Yes, humans can “hear” these frequencies, but not through the ear, but “hear.” This phenomenon is called the microwave auditory effect or Frey effect. Initially, it was recorded by people working near radars during World War II, and the sounds they perceived were not heard by others. It turned out that with the impact of pulsed or modulated microwave radiation on areas around the cochlea of the ear, it is absorbed by the tissues of the inner ear, accompanied by their thermal expansio

Dang! I know that it’s already the Mesozoic, but I still keep writing Paleozoic out of habit…

It’s quite intriguing to look back about 40-50 years ago — how did people work in an office back then, assuming you aren’t scheduling appointments like a doctor might, nor are you a lathe operator who needs to physically craft things, nor a scientist, but just a manager. First off, it’s already hard to envision such a project that requires sitting in an office instead of a place where something tangible is being made — like constructing a building, a bridge, or planting trees. But let’s strain our imaginations and visualize it. Most probably, it would have been a government job, regardless of the country. In the office, you would have had a desk and a telephone. You arrive at work and sit at this empty desk. Then, over the course of 8 hours, the options are either talking to coworkers (about work or otherwise) or making calls and solving little issues, should something unexpectedly break down in the processes. It’s hard to imagine that distractions from work-related interactions could only be non-work-related interactions with colleagues, and nothing else. Thus, it’s very likely that you’d be burdened with some tedious nonsense – like sorting papers into three piles. It’s interesting to see how everything has changed. And how many managers now don’t need to step out from behind their computers in their offices.

Mom finished another embroidery. 32x46cm, 47 colors, floss. She is 77 years old and this is her hobby. This one took three months. Some took a year. It seems the total area of the embroideries already exceeds the area of the apartment