Catching up with warmth

2024 Author: Seth Attwood | [email protected]. Last modified: 2023-12-16 15:55

"Today children learn the correct ideas about warmth already in the seventh grade."

(From the collection "Jokes of Great Scientists")

… The Kazakh steppe scorched by the Sun. Scientists from a small expeditionary group, wiping sweat, observe the saigas. These scientists conduct responsible scientific research. They want to experimentally confirm the words of Academician Timiryazev: "".

The methodology of our scientists is nowhere simpler. They track how much grass the animals eat in their natural environment. The calorie content of this feed - i.e. the amount of heat that is released when it is burned in a calorimeter is already known to scientists. It remains only to compare the amount of this “potential energy” contained in the food of the saiga with the work that its muscles produce during its life.

But … the longer the scientists observed, the more melancholy they became. You see, these saigas were somehow wrong. They ate a little - the number of calories in their rations turned out to be several times less than the energy consumption of their muscles. Fat reserves had nothing to do with it - what are your fat reserves in summer? The most offensive thing was that the saigas overturned all the "scientifically grounded norms": the calorie content of their food was clearly not enough for life, and they looked quite cheerful … Here is a charming saiga, winking at the scientists, gracefully lifting its tail and giving out another batch of poop. “Have you seen what he's doing? - one observer could not resist. - Mocks us, ruminant creature! - “Calm down, colleague! - responded the second. - On the contrary, she tells us: we have not brought the experiment to the end! This … the hay passed through the cow - it, dried, also burns! Locals use it as fuel! " - "Do you want to say, colleague, that this … this very … also has a calorie content?" - "Exactly! And we will measure it!"

No sooner said than done. The calorimeter had no fun when they burned poop in it - but for the sake of science I had to endure. However, the researchers had even less fun when they became convinced that the calorie content of poop is the same as the calorie content of the original feed. It turned out that at the level of Timiryazev's "potential energy contained in organic matter", the animal not only consumes much less than is required for the work of its muscles, but also releases as much as it consumes. That is, there is absolutely nothing left for the muscles to work. Our scientists were well aware that such curious conclusions were not for their reports. Therefore, they sprinkled ashes on their hair - those same burnt poop - and that was the end of it.

And so far, the situation regarding the "calorie content of food" is a hangover of some kind. If you ask nutritionists about how many calories a day should be consumed with food in order to “guaranteed to lose weight in two weeks,” they will explain everything to you in detail - moreover, they will take it inexpensively and will not blink an eye. Their job is like this … But we ask the academicians: where do the calories that saigas use to walk, chew, and lift their tails come from? And academics do not like this question very much. Painfully, he is uncomfortable for them. The maximum that you can achieve from them is an appeal to the fact that living organisms, they say, are the most complex highly organized systems, and therefore they, they say, have not yet been sufficiently studied. So you, uncles, in the framework of the study of living organisms, are you keeping mum about the results of calorimetric measurements like those described above? Or are you afraid that you will have to blush when the children laugh at you? Well, here's a proven folk remedy for you: rub your beetroot muzzle - if you blush, it won't be so noticeable.

How did academics come to this life? Okay, even if animate organisms are too difficult for them. But in an inanimate substance, which is subject to the action of only physical and chemical laws - is it then that questions with calories should be completely transparent? We are not talking about the phenomena that are found in accelerators and colliders. These are phenomena that anyone can reproduce in their own kitchen. It would seem that colossal practical experience should have been molded into completely clear ideas about warmth. But we will tell you how this experience really took shape.

Even ancient philosophers in the question of the nature of heat were divided into two camps. Some believed that heat is an independent substance; the more it is in the body, the warmer it is. Others believed that heat is a manifestation of some property inherent in matter: in a given state of matter, the body is colder or warmer. In the Middle Ages, the first of these concepts dominated, which is easy to explain. The concepts of the structure of matter at the atomic and molecular levels were then completely undeveloped - and therefore the property of matter that could be responsible for heat was a mystery. Philosophers, in the overwhelming majority, did not bother trying to find this mysterious property - but, led by the herd instinct, adhered to the convenient concept of heat as a "calorific matter".

Oh, how tenaciously they adhered to it - to cramps in the grasping muscles. Understand: the calorific matter, as it were, is transferred from hot to cold bodies when they come into contact. The more calorific matter in the body, the higher the body temperature. What is temperature? And this is just a measure of the content of calorific matter. If the calorific matter is transferred from right to left, then the temperature is higher on the right. And vice versa. If the calorific matter is not transferred either to the right or to the left, then the temperatures on the right and left are the same. Let the concepts of "calorific matter" and "temperature" turn out to be connected by a logical vicious circle, but otherwise everything was amazing. It was even possible to draw practical conclusions: in order to heat a body, it is necessary to add calorific matter to it - in comparison with what it already has. And for such an addition, a more heated body is required, otherwise the calorific matter will not be transferred. Shine! On the basis of these ideas, working heat engines were made! The principle of the indestructibility of calorific matter was even formulated, i.e., in fact, the law of conservation of heat!

Of course, today it is easy for us to talk about the naivety of these medieval quirks. Today we know that heat is one of the forms of energy, and the law of conservation of energy does not work for any one of its forms. This law works for energy as a whole - taking into account the fact that some forms of energy can be converted into others. But in that era when calorific matter was considered an integral part of the Universe, the principle of its indestructibility, due to claims to the universal scope, led philosophers to awe. For experimental confirmation of this principle - true, not on a universal, but on a local scale - these boxes with a double bottom, called calorimeters, were invented and put into use.

It is amazing: in the course of scientific and technological progress, from mechanical stopwatches, they first switched to quartz, and then to atomic clocks, from earth-measuring tapes they switched to laser rangefinders, and then to GPS receivers - and only calorimeters turned out to be absolutely irreplaceable in the matter of direct determination thermal effects. Until now, calorimeters serve their users faithfully: users believe in them and think that with their help they know the truth. And in the Middle Ages they were prayed for, protected from the evil eye, and even fumigated with incense - which, however, did not help much. Here, look: the process under study proceeded in a glass with heat-conducting walls, which was inside a large glass filled with a buffer substance. If, during the process under study, the calorific matter was released or absorbed, then the temperature of the buffer substance, respectively, increased or decreased. The measured value in both cases was the temperature difference of the buffer substance before and after the process under study - this difference was determined using a thermometer. Voila! True, a slight difficulty was quickly discovered. The measurements were repeated with the same test process, but with different buffer substances. And it turned out that the same weights of different buffer substances, acquiring the same amount of calorific matter, heat up by different amounts of degrees. Without thinking twice, the masters of thermal affairs introduced into science one more characteristic of substances - heat capacity. This is quite simple: the heat capacity is greater for the substance that contains more calorific matter in order to heat up by the same number of degrees, all other things being equal. Wait, wait! Then, in order to determine the thermal effect by the calorimetric method, it is required to know in advance the heat capacity of the buffer substance! How do you know? The heat masters, without straining, gave an answer to this question as well. They quickly realized that their boxes are dual-purpose devices that are suitable for measuring not only thermal effects, but also heat capacities. After all, if you measure the temperature difference of the buffer substance and know the amount of heat-generating matter absorbed by it, then the desired heat capacity is on your silver platter! And so it happened: thermal effects were measured on the basis of knowledge of heat capacities, and heat capacities were recognized on the basis of measurements of thermal effects. And if someone, not out of malice, but purely out of curiosity, asked: "What did you measure first - heat or heat capacity?" - then he was answered in this spirit: "Listen, smart guy, what came first - a chicken or an egg?" - and the wise guy understood that he shouldn't ask stupid questions.

In short: if you do not ask stupid questions, then everything was fine in the calorimetric method, with the exception of one nuance. From the very beginning, this method was based on the key postulate that calorific matter is only capable of flowing from more heated bodies to less heated ones. Then no one had thought of a simple thing: if this key postulate is correct, then over time the temperatures of all bodies will equalize - and, as they say, amen. However, if anyone had thought of it, they would reasonably have objected to him that God's plan could not contain such stupidity - and on this everyone would have calmed down.

In a word, the concept of calorific matter in science is comfortably warmed up. Therefore, our Lomonosov, with his rustic simplicity, did not fit into this idyll. After all, he did not adhere to certain concepts, he researched them - and offered more adequate ones in return. In "Reflections on the cause of warmth and cold" (1744) Lomonosov quite clearly formulated the cause of heat - which is "" of body particles. By the way, he immediately made a phenomenal conclusion: "". Today, a more highly scientific term is used - "absolute zero temperature", but the name of Lomonosov is not mentioned. After all, he had the imprudence to destroy the concept of calorific matter! So, he wrote that the philosophers did not show - "". “” If the philosophers had then used the methods of quantum mechanics, they would have come up with some kind of “reduction of the thermal function”. Although, with all the "medieval obscurantism", it was considered indecent to be so frankly idiot - it became commonplace only in the twentieth century. There was still a long wait … And Lomonosov sorted out the following misconception - about the weight of "calorific matter". "". Alas, the well-known Robert Boyle has done something wrong: when the metal is roasted, scale forms on it, and the weight of the sample increases - but due to the substance added as a result of the oxidative reaction. "", Moreover, "". But Lomonosov also did the control "".

Compared to these devastating arguments, the whole doctrine of calorific matter was childish babble - even apprentices in chemical laboratories understood this. But the academic masters did not recognize Lomonosov's rightness - they wisely kept a deathly silence. “On the case, we have nothing to argue,” they figured. "But it cannot be that we are all fools, and he alone is a genius." Moreover, this thought obsessively came to all academic heads. Although the academics did not come to an agreement, outwardly it manifested itself as a one-hundred-dollar world conspiracy. And these were all the most honest and noble people. As for selection - each other is more honest and noble. An honest one drove on an honest one and drove a noble one.

Take Euler, who was considered a friend of Lomonosov. When the Paris Academy of Sciences announced a competition for the best work on the nature of heat, it won the competition and received the Euler Prize, who wrote in the presented work: "" (1752). But this Euler case was an exception. The rest of the "honest and noble" kept silent and patiently awaited the death of Lomonosov (1765). And only after that, having waited another seven years to be faithful, they again started their hurdy-gurdy about calorific matter. You see, it was impossible to admit that Lomonosov was right. Now, if he had done any small thing - for example, exposed the delusions of the same Boyle, and that's it - then Lomonosov's law would be in textbooks now, as is the Boyle-Mariotte law. And Lomonosov got carried away and shoveled all the science of that time. Agree, do not write in textbooks "the first law of Lomonosov", "the second law of Lomonosov", etc. - when the score goes to many tens! Students will get confused! That is why fresh experimental facts, which could be interpreted in the spirit of calorific matter, passed with a bang.

And there are some facts. In those days, naturalists had a fashion: to mix such and such amount of cold water with such and such amount of hot water - and determine the resulting temperature of the mixture. Experience confirmed Richman's formula: the temperature value was a weighted average - in the particular case, with equal amounts of cold and hot water, it was the arithmetic average. And so: the chemist Black, and then also the chemist Wilke, started to check the Richmann formula for the case of mixing hot water not with cold water, but with ice - deciding that, at the melting point, “that ice, that water is one crap”. The result came out - today it can be said for sure - absolutely mind-blowing. The final water temperature for the case of initial equal ice weights at 0^OC and water at 70^OC turned out to be far from the arithmetic mean - it turned out to be equal to 0^OS. Mind-blowing? And then! Minds were so dark that they enthusiastically gave themselves up to the concept of "the latent heat of melting ice." According to this concept, in order to melt the ice, it is not enough to heat it to the melting temperature, which will require a certain amount of calorific matter to be communicated to it, in accordance with its heat capacity - it will also be necessary to propel an additional huge amount of calorific matter into the ice, which will go to the melting itself. True, during melting, the temperature of the ice does not change, and thermometers do not react to this additional calorific matter - that is why the heat of melting is called "latent". Everything is thought out! And, most importantly, experience confirms: where, they say, the water heat supply goes at 70^OC, if not melting ice ?! This is how we found the numerical value of its latent heat of fusion. Academics cried with joy - closing their eyes to the fact that the logic of Black and Wilke works under the indispensable preliminary assumption: the amount of warmth in nature is conserved. With this delusional assumption, Black and Wilke's results did indeed confirm the presence of calorific matter. Everything started over again. However, Lomonosov's efforts were not in vain: the present calorific matter was attributed to such a specific property as the absence of weight - otherwise, in fact, it turned out funny. And they released, instead of calorific matter, a weightless calorific fluid, for which they chose an apt name: caloric. And they became more and more beautiful than before.

Why are we talking about this in such detail? Because it is useful to know how this game about the latent heats of aggregate transformations appeared in physics - which is still considered a scientific truth. We'll have to say a few words about the “scientific nature” of this “truth”.

Imagine: the inner glass of the calorimeter contains water and ice - in thermal equilibrium with each other and with a buffer substance. A negligible rise in temperature, up to the so-called. liquidus points - and the phase equilibrium between ice and water will be violated: the ice will begin to melt. Where will the heat for this melting come from? From a buffer substance, or what? But then its temperature will drop, and the flow of heat "for melting" will stop. In fact, all the ice will melt, and the temperature will remain at the liquidus point. Scandal!

Maybe today's academics consider this result to be some kind of annoying exception, since in other cases, they say, ends meet perfectly - for example, when calculating the thermal balance of the tau-Ceti star. No, dear ones, you will not get off with an "exception" here. In your opinion, the formation of ice in open water bodies should also be accompanied by a thermal effect - only now the same “heat of fusion” should be released. You, my dear ones, took the trouble to figure out - what results should this lead to? Ice grows from below, and the thermal conductivity of ice is two orders of magnitude worse than that of water. Therefore, practically all of the "heat of fusion" should be released into the water under the ice. If we substitute the reference values into the simplest heat balance equation for the case under consideration, it turns out that the formation of a 1 mm layer of ice would cause heating of an adjacent 1 mm layer of water by 70 degrees (and a 0.5 mm water layer - as much as 140 degrees; however, already at 100^OIt would start to boil). How do you like this result, dear ones? Maybe you will say that we have not taken into account the thermal mixing of water in vain? Indeed, in the range from 0^O up to 4^OC, warmer water sinks, and colder water rises. What a! But, even under the conditions of such mixing, if there was a heat source on the surface of the water, the water above would be warmer than below. In fact, the typical Arctic temperature profile in water under the ice is as follows: water in contact with ice has a temperature close to the freezing point, and as the depth increases (within a certain layer), the temperature increases. This is obvious evidence: there is no heat flow into the water from ice, even from growing ice. Oceanologists realized this long ago, so they invented such a fool: "". What this heat does next, which is calculated, on a regional scale, in trillions of kilocalories - oceanologists no longer care; let the atmospheric engineers deal with this warmth further. One might think that oceanologists do not know that the thermal conductivity of ice is two orders of magnitude worse than that of water. Where, one wonders, are the Arctic expeditions heading over and over again, and what are the hydrologists doing there together with the meteorologists - are they cutting out ice sculptures, or what?

And there is no need to trudge to the Arctic to make sure that there is no heat release when the water freezes. On TV, MythBusters showed a highly reproducible experience. A bottle of supercooled liquid beer is neatly taken from the refrigerator. You poke over this bottle - and the beer in it freezes into ice flakes in a few seconds. And the bottle stays cold … This experience has tremendous popularizing power. Key words: “warm, cold, bottle, beer” - everything is very intelligible. Even for today's academicians.

Imagine how hard it is for these academics: since there is no "latent heat of fusion", you will not only have to rewrite physics for the seventh grade, but also make excuses - how some medieval chemists Black and Wilke have tricked them. And how can one justify oneself if academics still don’t understand the secret of that trick? Okay, let's show you. The secret is that ice at 0^O, after mixing it with hot water, it does not raise its temperature: it melts at a constant temperature. And until it melts completely, it is a source of cooling: the water in contact with it, which was at first hot, becomes warm, then cool, then ice … with equal starting weights of ice at 0^OC and water at 70^OС, all the resulting water will be at 0^OC. The case, as you can see, is simple. But no, they are demanding an explanation from us - but where, they say, did the heat that the hot water had? Friends, this question would be pertinent if the law of conservation of heat would work in nature. But thermal energy is not conserved: it is freely converted into other forms of energy. Below we will illustrate that a closed system is quite capable of changing its temperature - and even in different ways.

And as for such an aggregate transformation of matter as melting, it is obvious that it does not need any "latent heat". Heat the sample to its melting point - and maintain it if necessary - and the sample will melt without assistance. Those who watched the film epic "The Lord of the Rings" probably remember the last seconds of the Ring of Omnipotence. It fell into the mouth of the "fire-breathing mountain" - and now it lies there, lies … heats up, heats up … and, finally - a chomp! And instead of a ring - already spreading droplets. This scene was very successful for the filmmakers. Full sense of reality!

(An excerpt with a ring can be viewed at the link:

Gold has good thermal conductivity, and the ring was tiny, so it warmed up in its entirety at once. And, immediately in the entire volume it was heated to the melting point - immediately and melted, without unnecessary heat demands. By the way, eyewitnesses to the heating of scrap metal, for example, aluminum in induction furnaces, testify: it does not melt gradually, drop by drop - on the contrary, protruding fragments begin to float and flow at once throughout their entire volume. In the case of ice, the absence of unnecessary heat demands for melting is not obvious simply because the thermal conductivity of ice is much worse than that of metals. Therefore, the ice melts gradually, drop by drop. But the principle is the same: what is heated to the melting point - then immediately melted.

O. Kh. Derevensky

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