Freeman Dyson: physicist, heretic, predictor of the future

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Freeman Dyson: physicist, heretic, predictor of the future
Freeman Dyson: physicist, heretic, predictor of the future
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On February 28, 2020, the physicist Freeman Dyson, whom most of us know from the "Dyson sphere", died - the concept of a huge sphere that fully uses the energy of a star and gives room for life to quintillion people at once. However, in fact, this is not exactly his idea, but Dyson's contribution to other branches of science and technology was much more important. So much so that all Western media trying to write about his death faced a serious problem: a prominent scientist died, but because of "heretical" views, even in Dyson's obituary had to be strongly criticized. Let's talk about everything in order.

Freeman Dyson in Moscow in 2009, at his lecture "Heretical Thoughts about Science and Society" / © elementy.ru

Born in Britain in 1923, Freeman Dyson grew up in a family that was socialist and relatively religious at the same time. As a result, he carried through his life a rather unusual combination of relatively left-wing political and at the same time Christian views. Another unusual feature of his work is the constant switching of interests between the most diverse areas: from strategic bombers and tactical nuclear weapons, to astrophysics and quantum mechanics.

Bombs, conventional and nuclear

In 1942, while studying at Cambridge, he was "pulled" from the university and recruited to work in the Operations Research Department of the Royal Air Force Bomber Command (RAF) of Great Britain. It would seem, what can a dropout student do in such a place?

However, Dyson early showed the ability to creatively apply numerical methods to the analysis of a variety of practical problems and, oddly enough, already at this age was able to significantly influence the course of World War II.

He calculated the optimal density of the formation of the KVVS bombers that bombed German cities at night. They could not get into something specific, even with a radar sight, so the young researcher proposed such a density of strike groups, which would be enough for a massive destruction of urban buildings. The KVVS, based on such recipes, dropped a million tons of bombs on German cities, killing approximately 0.3 million people and ensuring, in 1944, a decrease in German industrial production by 1/12.

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From a modern point of view, such strikes were undeniably terrorist. The head of the bomber command Bomber Harris, even in 1944, promised, based on the effect of intimidating the Germans by bombing cities, that they would surrender and there would be no need to land troops in Normandy. But at the same time, it is clear that the very decision to launch the terrorist attacks was not made by a Cambridge student Dyson. His job was only to provide them with a slightly greater practical return.

The second attempt to help the KVVS, however, did not bring the young man luck. According to his calculations, two defensive turrets had to be removed from the British night bombers, because the sense of firing from them at night was not particularly great, but the speed of the bombers would have increased by 80 km / h. His proposal was not accepted by the military, who feared such radical steps.

I must say that the head of the bomber command was generally calm about the losses among his pilots, for which he was nicknamed the Butcher Harris. As a result, the KVVS lost twice as many flight personnel in the war as the Red Army Air Force, an achievement that is indeed difficult to achieve.

The work in the military field for Dyson did not end there.After World War II, he moved to the United States, where he consulted the military. In 1967 he published a special scientific paper on the effectiveness of the use of tactical nuclear weapons in Vietnam.

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In it, he analyzes the results of the headquarters exercises, which showed the great capabilities of tactical nuclear weapons in confronting the Viet Cong. In these exercises, the detonation of nuclear bombs along the supply paths of the Vietnamese guerrillas paralyzed the delivery of ammunition, destroyed the bridges in their supply networks, as well as a large number of manpower. Since the Viet Cong had no atomic weapons, the American military considered their use here justified, although the political complications after its unilateral use raised questions even among the most "militant" generals.

Dyson and his co-authors looked at the issue from a cost-benefit perspective and found tactical nuclear weapons to be overrated in every sense. First, they pointed out, during the headquarters exercises, the duration of operations was short. Therefore, a tactical nuclear bomb that blocked the road in the jungle for a month (before filling the crater with soil, and so on) was formally an excellent solution, cutting off the supply of the partisans.

However, in real life, the war lasted more than a month. On first use, the bomb knocked down all the trees in the jungle for a kilometer around, and it would be difficult to get around a large crater on the road. However, if the Viet Cong were to clear a bypass path, further nuclear attacks along the same route would be ineffective. “A tree can only be knocked down once,” the work notes soundly.

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In general, nuclear strikes could not undermine the Viet Cong numerically. His people were scattered in the jungle, there was no understanding of where exactly they were there. A nuclear bomb strikes only tens of square kilometers at a time, and the jungle area in South Vietnam is many tens of thousands of square kilometers. The use of thousands of warheads is relatively expensive and also provides some radiation contamination that poses a threat to both civilians and, to a lesser extent, US military personnel. Although this level did not reach lethal in most cases, it would create certain difficulties anyway.

And most importantly, Dyson and co-authors emphasize: if the USSR decides to supply the Viet Cong with tactical nuclear weapons, for the States their decision to start using them will be the beginning of defeat. Almost all of their ground forces in Vietnam were stationed at 14 bases, not covered by the jungle. Strikes against them would have led to the loss of almost all American personnel and a turning point in the war in favor of the Viet Cong.

It is doubtful that the Pentagon, despite its war games, would have gone to carpet nuclear bombing in Vietnam without Dyson's work. Nevertheless, it was still useful and remains so today. Such sober quantitative assessments deprived the military of the illusion about a certain "omnipotence" of nuclear weapons, significantly reducing the desire to use them in other conflicts, for example, with the USSR. The study showed that the military benefits of using tactical nuclear weapons are so small that they cannot justify the dangerous political consequences.

Dyson's work was brilliantly illustrated by the later history of the Vietnam War. The United States dropped 7, 8 megatons of bombs and missiles there (TNT equivalent of hundreds of Hiroshima) with a total area of ​​continuous destruction in millions of square kilometers, but they lost the war: even a very large force is useless when you do not see exactly where it should be used.

Quantum Mechanics: Popularizer or Discoverer?

In 1948-1949 in quantum electrodynamics - describing the electromagnetic field on the basis of the idea that its carriers are particles, quanta (photons) - a difficult situation developed.Japanese Shinichiro Tomonaga and American Julian Schwinger have created two different approaches to describe the behavior of particles in quantum electrodynamics, and physicists around the world have tried to figure out which one is better.

At that time, Dyson, who moved to the United States, worked with physicist Richard Feynman, who created the Feynman diagrams - a computational tool whose use at that time no one but the creator himself could understand. Dyson, without even having his own dissertation (he never defended it), was able to delve into a very complex area of ​​physics, which was extremely "new" at that time, and show that from a mathematical point of view, the approaches of Schwinger and Tomonaga are identical, and the Feynman diagrams are perfect to describe the interaction of particles in quantum electrodynamics.

Interestingly, Feynman, Tomonaga, and Schwinger received the Nobel Prize for this discovery, while Dyson did not. Why? Most likely, the fact is that it was not customary to present this award to more than three people. Or maybe it was that Dyson played the role of an integrator and popularizer here rather than a pioneer, because before him the scientific community as a whole simply did not understand the same Feynman diagrams.

Dyson sphere

In the late 1950s, the scientist's attention was attracted by the problem of the Fermi paradox - why we do not observe extraterrestrial civilizations, although taking into account the number of stars and the estimated number of planets, the Universe should be teeming with them.

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It was not known in the West at that time that the “Fermi paradox” was first formulated by Tsiolkovsky in the 1930s, and he was the first to propose a satisfactory solution to it. Not knowing about him, Dyson tried to imagine what traces of extraterrestrial civilizations, available for observation through telescopes of that time, could be.

In 1960, he put forward the hypothesis of the Dyson sphere - one of the designs of extraterrestrial civilizations that could be seen from space. The sphere should consist of many independent flat elements surrounding the star on all sides. From the inside, it is covered with solar panels, as well as residential modules where intelligent beings can dwell. The design allows to use the main part of the luminary's energy, providing civilization with unlimited energy possibilities for billions of years, as well as living space for hundreds of quintillion beings such as humans.

From a scientific point of view, the value of the hypothesis of such a mega-construction is that it should give out an extraterrestrial civilization with its head. By blocking visible light from the star, the sphere will inevitably lose some of its energy as infrared radiation. In the Universe, there are no such powerful sources of infrared radiation of natural origin, but at the same time they do not give visible light. After the Dyson hypothesis, having seen such objects, astronomers will quickly focus their attention on them and be able to identify potential representatives of other civilizations.

The design, with its scope and seeming practicality, amazes the public and, starting with Star Trek, has been actively circulating in pop culture. This is probably why the "Dyson Sphere" is the most familiar to most of us side of a scientist's work. All the more amusing are two points: he is not quite the author of the idea, in addition, there is no point in building any Dyson spheres.

Let's start with the author. Freeman Dyson himself noted that his "sphere" is the development of the idea of ​​the English science fiction writer Olaf Stapledon (from the book "The Creator of the Stars" in 1937). There, however, there was no solid sphere - only a "ribbon" of flattened living modules in the equatorial plane of the star. The reasons for the difference are that the polar parts of the Dyson sphere themselves have unstable orbits, and to keep the sphere they would have to "steer" all the time, for which they would have to have engines and spend part of the received energy. Partially Stapledon was ahead of Tsiolkovsky in his fantastic work of 1894, although his scale of such a "tape" is even smaller.

Until now, not a single object similar to the Dyson sphere has been discovered and, we dare to assume, will never be discovered. There are two reasons for this.

The first is technical: to build a sphere, you need a substance with a mass of about the size of Jupiter, that is, more than half of the substance of all the planets of our system. However, Jupiter, like all the so massive planets of the Universe, is composed mainly of hydrogen and helium. Solar panels and residential modules cannot be built from these gases. Of course, you can import matter from neighboring planetary systems, but it is much easier not to drag quintillion tons from dozens of stars, but to transport the required amount of your own population to them. Any conceivable colonization of other planets is technically much more realistic than the construction of such a sphere. By the way, hydrogen from Jupiter can produce the same energy as the Dyson sphere around the Sun for 300 million years in a row (if used in thermonuclear reactors).

The second reason for the uselessness of spheres for extraterrestrial civilizations is that, judging by our civilization, developed societies are losing population, not increasing it. Having reached a high level, civilization no longer has the ability to increase the number of its carriers to hundreds of quintillions, who would really need the Dyson Orb.

Moreover, biologists have serious suspicions that an advanced civilization - at least in its present form - is leading to the degradation of the mental abilities of its carriers. Perhaps to the level of oligophrenia, followed by the collapse of technogenic civilization in principle. Terrestrial civilization runs the risk of entering this stage in a thousand years. What a sphere of Dyson here: it would be nice not to forget how to read and write.

Dyson's idea was quite sensible for 1960, when it was not completely clear how much mass would be required to create a sphere and that population growth, rapid at that time, with the development of civilization was replaced by extinction, and so on. And today the key grain of his idea is still valuable: advanced extraterrestrial civilizations should leave technogenic traces visible to astronomers, albeit not as gigantic as the Dyson sphere.

On the atomic bomb into space

In the 1950s, Dyson was attracted to the Orion project - a giant (at least SpaceX Starship, no less than four thousand tons) spacecraft, flying on the detonation of small and relatively "clean" thermonuclear and nuclear charges with a capacity of a fraction of a kiloton. According to the project, the ship was driven into action by detonating bombs behind a stern steel plate covered with a thin renewable layer of graphite. When detonated, the bomb evaporated a thin disk, ejected with it, the plasma from the evaporated disk hit the stern plate, giving impetus to the ship.

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When launched from the Earth (from a nuclear test site), a bomb at 0.1 kilotons should have exploded astern once a second, and when flying in space, where it is easier to use atomic weapons, at 20 kilotons. By the way, during the detonation of a thermonuclear bomb on Eniwetok Atoll, graphite ablation was tested experimentally. Steel balls nine meters from the explosion of the megaton class remained intact: all the energy was carried away by the evaporated thin graphite shell, showing the accuracy of the calculations according to Orion. There were also atmospheric tests of models of explosives, on ordinary explosives:

Dyson also calculated more powerful versions of the "nuclear ship" - for interstellar travel, weighing tens of millions of tons. It turned out that with a plate with a diameter of 20 kilometers and a bomb detonating behind the stern every 100 seconds, an ablation layer is not even needed: the metal plate will cool down by itself, due to the infrared radiation emanating from it when heated.

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Such a ship could accelerate up to 1000 kilometers per second in a hundred years, for another 1100 years - fly to Alpha Centauri and slow down near it for another 100 years. Due to a million tons of payload and millions of tons of weight of the structure (automatically protecting from space radiation), many colonists could be accommodated in the ship. On the way, they would receive food from hydroponics, and upon arriving at the place, they could begin to colonize it.Perhaps there was also the reaching of the nearest stars at speeds of 10 thousand kilometers per second and in just 130 years, but already with a much lower load (research, not a colonization ship).

Ships to the nearest stars were quite expensive: research would cost 10% of 1960s US GDP, and colonization would cost 100%. More modest options for landing on Mars were much cheaper, comparable to the lunar program. However, in 1963, the USSR and the USA banned nuclear tests in the atmosphere, on which the project was closed.

In modern conditions, it may make sense if bombs are detonated in the Earth's orbit and beyond: after all, it takes too long to fly on chemical rockets beyond the orbit of about Jupiter, astronauts will "catch" a lot of cosmic radiation. Nevertheless, despite all the prospects of the project, today it is out of sight of existing players. States do not want to fly into deep space, and SpaceX does not have access to nuclear weapons, and the colonization of Mars is quite possible without thermonuclear starships.

All this does not diminish the importance of the Orion project and Dyson's developments within its framework. And to this day, 60 years later, this very concept is the most realistic way to reach the nearest stars.

How a physicist became «heretic»

Freeman Dyson took up climatological issues in the 1970s, at the very beginning of the scientific discussion about global warming, caused by the famous theses of the Soviet scientist Mikhail Budyko.

At the same time, Dyson was the first in history to express an extremely important thesis: the climatic consequences of anthropogenic CO2 emissions into the atmosphere are much less than non-climatic ones. The physicist showed excellent scientific flair in related fields, noting that carbon dioxide is essential for the development of plants and, by stimulating this development, will play a greater role than climate change caused by the same gas. Moreover, in his opinion, fears of warming are generally exaggerated.

Dyson was one of the first to draw attention to the fact: during the Holocene climatic optimum several thousand years ago, the Sahara was a savannah, not a desert (with warming, water evaporates more actively from the oceans, which causes more precipitation on land). He noted that there is clearly nothing wrong with such consequences of warming as overgrowing of deserts.

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After 40 years, Dyson's ideas were fully confirmed. In 2016, it was revealed that anthropogenic CO2 emissions have led to global greening. This is a phenomenon of colossal proportions, within which only since the early 80s the area of ​​leaves on the planet has grown by the size of the Amazonian jungle and continues to grow. As the researcher summed it up: “Measurements from space show that the whole Earth is getting greener due to [emissions of] CO2, and it also increases crop yields, helps to expand forests and accelerate the growth of the entire biological world. This is more important and more definite than the impact of this gas on the climate."

Of course, in the 1970s, no one looked so far into the future, so then the scientist's ideas were rejected. Nowadays he is completely avenged: the modern scientific community is still comprehending the fact of global greening, which Dyson anticipated so long ago. Because of this, the Western media, noting his contribution to science, still write "but in the discussion about global warming, he took the wrong side."

Dyson several years ago tried to give an answer to the question of why the false point of view about the "fatality" of global warming and anthropogenic CO2, having once established itself, still does not want to give up its positions - in spite of facts such as global greening. He believes that it is a matter of "tribal" thinking: they say, people for hundreds of thousands of years lived in conditions of primitive tribes, where submission to authorities was more important than critical thinking. Therefore, once established opinions get stuck in the minds of even scientists for so long: after all, they are also people and are often prone to "tribal thinking."

This does not seem entirely accurate to us.The submission to authority described by Dyson is characteristic of human tribes only since the Neolithic: among hunter-gatherers, blind submission to the authority of the leader or elders too easily ends in death on the hunt, where you have to think for yourself. The life of a farmer is more predictable, and the importance of authorities is higher - after all, it is in their hands that excess food accumulates, which can be stretched out in a hungry year (the hunters cannot have large reserves of food in the hands of the authorities of the tribe).

Nevertheless, the researcher is right in the sense that insensitivity to his "heretical" views on the climate may indeed be due to the peculiarities of archaic thinking. Historically, people have been wary of everything new and incomprehensible. The tendency to ascribe an ominous nature to the incomprehensible is relatively rational: in the Paleolithic, seeing an unfamiliar beast, it was better to "overlook" than "overlook". Excessive caution took only time, but lack of caution was life. This is why we fall into stress so easily, even from seemingly insignificant causes.

In our time, due to the rapid development of science and technology, there is always a lot of unfamiliar around, and the habit of expecting ominous consequences from everything obscure no longer helps, as in the Stone Age, but seriously interferes. In England, a court recently banned the expansion of Heathrow Airport because of fears that this will increase global warming, a carbon tax is being introduced around the world and a lot of other irrational steps are being taken, caused by nothing more than fear.

All this means that Dyson's ideas are not only retaining, but also gaining relevance. Looking at his life from today, we can say that as a researcher he lived the 96 years allotted to him extremely successfully. Most likely, in the next decades we will see many more confirmations of his ideas.

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