The temperature and pressure of science fiction - part 1/3

The note offered to your attention tells about the space of states of matter. Which, in a sense, is more extensive than the space of distances between objects in space, and sometimes it is also difficult to overcome.

I want to show that the phenomena of nature can be complex and non-trivial even in conditions very far from earthly ones. What is the main obstacle to their study is not cosmic distances, but the inability of our imagination and intuition to work in unfamiliar conditions. That life and mind may need to be sought not only on the surfaces of earth-like planets, for they are only a tiny fraction of the diversity of the Universe.

And that understanding of this diversity will probably require artificial intelligence - probably more so than rockets and astronautics.

Part 1. pT chart

Let's look at a random point in the universe. To clearly understand what is happening in it, you need to measure dozens of physical parameters. The most important of these are pressure and temperature. They set the aggregate state of matter, and, therefore, determine which physical and chemical processes will prevail in it. And this determines the geology, biology, and much more. By changing these two parameters even slightly, you can get an environment quite unlike the one you started with. Pressure and temperature are the two coordinates of the “phase space”. And in this space it is possible, according to the conditions at each point, to display our entire Universe.

All, of course, I did not draw. But a couple of examples and more or less studied boundaries on the diagram caused:



In terms of temperature, the phase space familiar to us extends from 0.002 Kelvin in laboratory refrigerators ^{[ 670 ]} to 30 million degrees in the nuclei of O class stars and modern thermonuclear plasmas. The upper limit, of course, is very conditional. So, in pulsed Z-pinches, the temperature is driven in ^{[ 655 ]} and in a billion degrees.

By pressure, the distance between the boundaries is even greater: almost 60 orders of magnitude.

At the left edge of the diagram, there are conditions in the cold regions of intergalactic voids (the so-called voids): ~ 10 ^-27 atmospheres, ~ 10 degrees Kelvin ^{[ 270 ] [ 280 ]} . The gas density there is units of hydrogen atoms per cubic meter. It may seem that the concept of pressure does not apply to such rarefied matter. That it is just a vacuum with a pair of atoms lost in it. But recall that a vacuum is called a medium with a path length of molecules larger than its (medium) size. The run of hydrogen before colliding with another atom in such voids is about 1 parsec. However, the size of voids is tens of mega parsecs. Obviously, on such scales, hydrogen in them has to be considered a continuous medium, with its own hydrodynamics, flow, sound and shock waves. Simply, all this is very large and, from a human point of view, insanely slow.

The right boundary can be drawn according to the conditions in the center of the neutron star. Estimation of pressure and temperature in it gives 10 ²⁹ atmospheres and ~ 1 million Kelvin. It is not known what kind of matter meets these conditions - whether it is still neutrons, or already a quark fluid.

Inside this square there are conditions on the surface of Mars (0.00636 atm, 214 K), Venus (92 atm, 736 K), Pluto (10 ^-5 atm, 50 K), in the center of Jupiter (3.6 * 10 ⁷ atm, 23 thousand degrees) and the Sun (2.3 * 10 ¹¹ atm and 1.6 * 10 ⁷ K) in the hot and cold regions of the interstellar medium (5 * 10 ^-19 atm, 3 * 10 ⁶ K and 1 * 10 ^{-1 5} atm, 10 K).

For convenience, we introduce a scale bar. Logarithmic, of course. In fractions of the total differential parameters in the picture. If the 100% temperature range is 10 ¹¹ times, then 1% of this corresponds to a temperature difference of (10 ¹¹ ) ^1/100 = 1.318 times. That is, on the scale of the Universe, a 1% step up from room temperature of 293 K means heating up to 1.318 * 293 = 386 K, or 113 Celsius. As in a good bath.

By the pressure of 1% of the “Universe” difference, the ratio is (10 ⁶⁰ ) ^1/100 = 4.074 times. As between sea level and height of 10 kilometers.

Finally, for the center of reference we will accept “normal” conditions: a pressure of 1 atmosphere, a temperature of 293 Kelvin, i.e. 20 Celsius.

And let's see what and how changes when moving away from this center.

Nightstand Square Radius

Without assistive devices, a person survives only in a narrow range of temperatures and pressures ^[10] . In the picture, it is roughly outlined with a green ellipse, and with a yellow rectangle it is ± 1%.



Approximately below +10 C people freeze. Above +30 overheats. With a pressure below 0.5 atm, few people can live and work. Above 4 atmospheres comes nitrogen anesthesia, well known to scuba divers.

At the same time, the modern human habitat on Earth is much wider. But the history of its settlement is not primarily kilometers of territorial expansion, but the development of environments with new temperatures and pressures. Where behind each step are serious inventions, perceived today as routine.

The oldest of these technologies are tens of thousands of years old. This is the ability to make warm clothes, portable housing, and, of course, make fire ^[110] . Thanks to this trinity, people have gone beyond the lower boundary of the green oval. And they settled most of Eurasia and America, including the Far North, Greenland and Alaska, where the frosts of weeks go to tens of degrees below zero.

Tropics with temperatures above +30 C have been inhabited for a long time. But without the “planting” of sanitation and hygiene among the population, without sewage, plumbing and even the most primitive refrigerator ^{[ 115 ],} they would still remain very deadly places. Add a conditioner to the picture - and get a tourist Dubai in the middle of a joyless desert.

The pressures below 0.5 of the atmosphere were confidently mastered only in the 20th century, thanks to the industrialization of two technologies: the creation of sealed rooms and life support systems. All intercontinental passenger aircraft, and to a large extent the cultural coherence of our world, rest on this. Indeed, at any time in the air at altitudes of 8-12 kilometers there are half a million ^{[ 120 ]} passengers traveling between cities of our planet.

In the development of high pressures, humanity takes only the first steps. Yes, in experiments with pressure chambers, people lived at 70 atmospheres ^{[ 130 ]} , and submarines hide in oceans at depths up to half a kilometer ^{[ 140 ]} . But this can hardly be considered a full-fledged presence.

Echoes of this expansion, by the way, can be found in the literature ^{[150], [170], [180], [190] of the} 19th and 20th century.

Unlike humans, animal inventions (almost) do not. Therefore, even on Earth, organisms are separated by dissimilarity of conditions, much stronger than distance. An average polar bear travels 3,400 kilometers a year ^{[ 360 ]} , but it will never meet a desert scorpion in its life. Deep-sea fish cannot be quickly lifted to the surface, and in the area of ​​the Vostok station until the appearance of man millions of years did not even have microbial life - although the bacteria had definitely been thrown by the wind there.

Having finished with a one-percent neighborhood, we will step back a bit and take a look at 10%.

The earth, with its oceans, subsoil and stratosphere, almost fits ^{[15] [ 580 ] [ 590 ]} into a 10% rectangle. Human conditions are a tiny speck on this scale:



To the right and at the top of the center, we find the limit of mechanical engineering applied by the orange line. From the solid matter known to us, in principle, it is impossible to build a macroscopic and continuously operating device that would withstand the pressure and temperature drops to the right and above of this curve. Its pivot points are:

• Room temperature, 27 thousand atmospheres - ultimate ^{[ 680 ]} martensite-aging steel [2800 Maraging steel]. Diamond, however, is harder, but fragile, and we cannot build bridges and cars out of it.
• At 800-1000 C, the ultimate strength is achieved, no doubt, by heat-resistant alloys for turbine blades. For each degree they win is an increase in the efficiency of aviation engines, and each pascal of strength is a reduction in weight and gain in the cargo being transported. Therefore, the struggle for these parameters is serious. At 1050 Celsius, these alloys can hold a load of up to 4 thousand atmospheres ^{[ 690 ]} .
• With more heating, the list of construction materials is thinning, quickly going down to two: tungsten and graphite. At 3273 K, according to ^{[ 700 ]} , tungsten still withstands about 140 atmospheres in tension.
• TaC tantalum carbide is probably one of the most refractory substances. It can remain solid up to ~ 3800 Celsius. That is, if we really need to create something mechanical, without cooling that works under such conditions, then it is still somehow doable. But at 4000 C - that's all. There is nothing.

Within a radius of 10% you can still find a lot of amusing from a daily point of view:

• With a pressure of ~ 50 atmospheres and a temperature of ~ 10 ° C, you will find that the liquid can float on gas (namely, NaK alloy on compressed xenon ^{[ 30 ]} ).
• If the medium is cooled to -80 degrees, the exhaled carbon dioxide will freeze, the sleigh will stop sliding over the snow, the pace of most chemical reactions will slow down a thousand times, and the solvent for a hypothetical life in such conditions may be ... methyl alcohol.
• At 140 atmospheres, carbon dioxide forms lakes at the bottom of our oceans ^[25] , and a little higher methane is bound to water and settles in the form of solid clathrates like ice ^{[ 28 ]} .
• Everyone knows that sound propagates through the air, but not in a vacuum. But what happens if you “slowly pull the plug out of the socket”, smoothly moving from the first to the second? With the pressure drop, firstly, the sound transmission from the speakers to the air will deteriorate. Secondly, the absorption in the air will increase - and the stronger, the higher the frequency ^{[340], [ 350 ]} . Somewhere at ~ 0.3 Pascals (conditions on the Triton) the path of the half-damping of the note “la” (440 Hertz) will be reduced to one meter. Sound notification through the air in such conditions will become almost impossible, not to mention the voice communication.
• Stony minerals dissolve very well in superheated water vapor. And it is dissolution, not a chemical reaction. Thus, at 2000 K and 2000 atmospheres, the equilibrium quartz content of SiO ₂ in a pair is about 2.2% (according to [ 710 ]); The solubilities of iron oxide FeO and aluminum Al ₂ O ₃ are about the same. On a hot planet with an atmosphere of water vapor, all these minerals will be transported by the wind just like water in our conditions.
• When pressure drops strongly, metals begin to “float”, ceasing to be solid in the engineering sense: aluminum at 400–500 atmospheres, steel at 25 thousand ^{[ 680 ]} , and basalt at 1-3 thousand atm ^{[ 90 ]} . Such pressures in the Earth are created at depths of 4–12 kilometers, which, in fact, determines the beginning of the transition from the crust to the mantle. Therefore, it is sometimes easier to describe rocks that are significantly deeper (and at kilometer scale) as a viscous liquid than as a solid substance. Even more deeply, one has to forget about the "incompressibility" of solid bodies. So, at 350 GPA - pressure in the center of the Earth - copper will be compressed in volume 1.7 times ^[60] , aluminum - in 2.2, lead ^[70] - in 2.4.
• To the left and below the triple point of helium (2.177 K, 5043 Pa) fluids disappear in the world. All matter becomes either solid or gaseous. However, this point still did not fit on our schedule, but I applied hydrogen (18.84 K, 7040 Pa). Liquid to the left and below it - units.

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Finally, look at the phase diagram of hydrogen ^{[ 100 ]} :



One of the simplest substances in the Universe exhibits at least eight different states depending on temperature and pressure. Even a space that is stupidly filled with hydrogen alone is potentially eight very different worlds! What then to speak about the variety of states of substances more complex?

And now about literature and art

Using the ratings [ 380 ], [ 390 ], [ 400 ], I gathered together a few hundred titles of Western, Soviet and Russian science fiction. Added to them books read in person. I filtered, leaving only those that I clearly remember, where at least in one episode the action takes place outside the Earth, and where it is possible to estimate the temperature and pressure in the scene of action, at least by an order of magnitude.

And put them on the pT-diagram:



Her careful examination allows us to make several observations:

1. The fat blue spot near the center is 53% of the works, the action of which takes place at a pressure of one atmosphere and a room temperature, up to the weather. Saraksh, Pyrrhus, Dune, Tormans, Leonida, Enzia, Stepyanka, Arkanar - all these alien worlds actually depict the Earth and only the Earth. We are talking about space fiction, I remind you.

2. 11% of books almost merge with this group, where the authors decided to retreat from earthly conditions by a fraction of a percent. Say, Strugatsky's “Country of Crimson Clouds” with a temperature under 90 C and a pressure of ~ 1.1 atmospheres, Heinlein's “A Farmer In the Sky” (something like 0.5 atm and 220 K), or Azimov, who wrote the pressure meticulously At 1.05 am, the atmosphere on Malyshka in Sucker's Bait.

3. Another 11% of the plots are developing in a “vacuum”. But this development does not depend on whether the ambient pressure is 10 ^-5 or 10 ^-20 atmospheres (here's the problem, by the way: how to distinguish one from the other with the help of “stones and sticks”?) Because neither for the authors nor for the narration the difference no, I attributed to all these works the same lunar pressure of 10 ^{-1 5} atmospheres, and, where there are no references to temperature, its indoor value is 293 K.

4. About 25% of books contain episodes where at least one parameter is significantly removed from the earth and moon. These are, for example, Clifford Symak, "The City" (Clifford Simak, City), the chapter on Jupiter; Boris Shtern, "Breakthrough over the edge of the world"; Strugatsky, "The Way to Amalthea"; Vernor Vinge, "Depth in the Sky"; Sergey Pavlov, "Moon Rainbow".

5. Books, where a significant part of the action develops at the same time far from earthly temperatures and pressures, and where it matters, units. Among them are:

• Clement Hall, “At a Critical Point” (Hal Clement, Close to Critical)
• Andy Weir, The Martian (Andy Weir, The Martian)
• Georgy Gurevich, "Invitation to Zenith"
• Alexander Belyaev, "Air seller"
• Robert Heinlein, "I have a spacesuit - ready to travel," chapters on Pluto
• Larry Niven and Jerry Pournelle, The Mote in God's Eye. Conditions in the star, where they intercepted alien ships, a rough estimate. As you can see, I even counted such small episodes.

These are units of percent from fiction "space", and a percent share from a fantasy as a whole. The works of this group are often distinguished by low artistic merit, which, as we shall see, is quite a reasonable explanation.

6. No work familiar to me is removed beyond ± 25% of normal conditions.

At first glance, even 1% of books with unusual environments are not such a bad number. But look at the question wider. Suppose someone promises to make a list of attractions of the city. After much work prepares the document. In which 64% are devoted to the peculiarities of the author's apartment, 11% - the roofs of his house, and only about 5% of the notes begin with the words "and now look at the next street ..." This can be a wonderful list, it can be great and informative. But it is obvious that because of the extremely uneven coverage, almost nothing interesting in the city was on the list. The same is true, alas, of the coverage of modern fiction: the multitude of points near “normal conditions”, single hits beyond their limits, and immense untouched spaces far from them.

It will be objected to me now, and it will be fair to argue that the virtues of good fiction are not in describing physical phenomena in the depths of Betelgeuse.

It's true. The significant merit of the authors mentioned is primarily in the study of human behavior in the face of the unthinkable and incomprehensible. In making great stories. In anticipation of technology and analysis of the development of mankind. In inventing ideas, strange and surprising so that their non-standard is already all recognized self-worth. Thought experiments of Lem, Dick, Strugatsky and Bradbury, even if they were set at a pressure of one atmosphere and especially at room temperature, sometimes gave us no less to understand human and humanity than research in fully equipped laboratories. And fiction is not physics. She is not required to write about new temperatures and pressures. In the USSR, in the 60s, by the way, they tried to force them somehow. The horror turned out. I have one sample on my shelf. So wild that it can not be thrown away.

All this is true.

But it is also true that science fiction, the same science fiction, that even some 50 years ago was calling people into space, today fell out of the last car! The train of physical reality left, and she, without even noticing it, continues to dream about something alone on a cold platform. And this gap is increasing every year.

It seems that fiction - like engineering, and human physiology - also has its “habitat”. You can draw it on a pT diagram. And he has his limits.

Continuation