Book summary “A choice of catastrophes”: summary

Introduction

You often confront anxieties about the end of the world, whether through cosmic events or human actions. You worry about nuclear war, resource depletion, and natural disasters, finding it difficult to separate realistic dangers from apocalyptic myths.

Isaac Asimov analyzes potential existential and civilizable threats to humanity in A Choice of Catastrophes. The central idea is that you can divide these perils into five classes, ranging from universal destruction to the collapse of civilization. You learn that all imminent dangers can be avoided through rational thought and scientific foresight.

The book explores physical, geological, and biological threats across fifteen detailed chapters. You discover how the universe, the sun, the earth, and human societies face various forms of doom.

• How do you distinguish inevitable cosmic shifts from human-made dangers?
• Can you survive the long-term evolution of the sun and the universe?
• What actions can you take to prevent the collapse of civilization?

1. The Day of Judgement

Humanity has long conceptualized the end of the world through mythological and religious frameworks triggered by historical persecution and social crisis.

Scandinavian mythology reflects a harsh subpolar environment through the tale of Ragnarok, where gods, giants, and the universe ultimately perish in a holocaust. The tale of Ragnarok as known today is preserved in the writings of Icelandic historian Snorri Sturluson, who lived from 1179 to 1241.

The concept of the Messiah and a future golden age arose among the Jews as a reaction to military defeat, exile, and foreign domination. The prophet Joel around 400 BC first expressed the literary notion of a specific Judgement Day in the valley of Jehoshaphat. Persecutions by foreign powers repeatedly triggered apocalyptic literature in Jewish and Christian traditions, anticipating an imminent end of the world. The Book of Revelation was written around AD 95 during the reign of the Roman emperor Domitian.

2. The Increase of Entropy

Nicolas Copernicus published a book in 1543 placing the sun at the centre of the cosmos. Galileo later used a telescope in 1609 to confirm this with observations of Jupiter's satellites and Venus's phases.

The second law of thermodynamics governs all physical change by ensuring that entropy in the universe constantly increases toward an ultimate heat-death.

John Wallis in 1668 investigated colliding bodies and formulated the conservation of momentum. Hermann von Helmholtz established the conservation of energy in 1847. Albert Einstein argued mass was a form of energy in 1905.

Nicolas L. S. Carnot studied heat flow in steam engines in 1824. Rudolf J. E. Clausius suggested the evening-out process in 1850 and formulated the second law of thermodynamics.

The current estimated age of the universe is 15 billion years. The minimum estimated time until the heat-death of the universe is 1,000 billion years.

3. The Closing of the Universe

The scale of interstellar distances was first established in the nineteenth century, revealing that stars and galaxies are separated by vast expanses measured in light-years. Light travels at nearly 300,000 kilometres or 186,000 miles per second, making a light-year about 9.44 trillion kilometres or 5.88 trillion miles.

Friedrich Wilhelm Bessel determined the distance of a star in 1838 to establish the scale of interstellar distances.

Astronomical discoveries reveal an expanding universe originating from a Big Bang that will either expand forever into cold darkness or eventually contract into a new cosmic egg.

What was once thought to be the entire universe is actually just one of billions of galaxies extending across billions of light-years. Edwin Hubble used the 100-inch telescope on Mount Wilson to resolve stars in the Andromeda nebula and prove its massive distance. Observations of galaxy spectra reveal a universal red shift, indicating that all galaxies outside our local group are receding from us at high speeds.

Georges Lemaître suggested the universe started from a compressed cosmic egg that exploded. A. A. Penzias and R. W. Wilson of Bell Telephone Laboratories discovered the uniform radio-wave background glow in 1965. Whether the universe will expand forever depends on its average density of matter.

4. The Collapse of Stars

Planets are compressed into spheres of intact atoms by gravity. Stars possess masses ten thousand to ten million times that of Earth, and their colossal gravitational fields smash electron shells and liberate atomic nuclei at their cores.

Massive stars generate gravitational fields strong enough to crush atoms, form black holes, and power energetic quasars through accretion discs.

The sun has a mass formed out of roughly six trillion trillion kilograms of rock and metal and remains 12,750 kilometres or 7,900 miles in diameter. Nuclear reactions generate expansive heat balancing gravity, but this fuel is finite.

As a star contracts, its escape velocity increases. Once it reaches the speed of light, it has reached its Schwarzschild radius. The Earth would reach its Schwarzschild radius at a radius of 1 centimetre or 0.4 inches, and the sun at 3 kilometres or 1.9 miles.

Quasars derive their intense luminosity from matter spiralling into central black holes via an accretion disc. The X-ray source Cygnus X-1 represents a black hole with a mass up to 8 times that of the sun orbiting a blue star.

5. Collisions with the Sun

While stellar collisions, stray black holes, and antimatter present theoretical hazards, their actual probabilities in the galactic outskirts are extremely low.

Stars exhibit proper motion across our line of sight. Edmund Halley discovered in 1718 that stars like Sirius, Procyon, and Arcturus shifted positions compared to ancient Greek records. William Herschel later deduced in 1783 that the sun itself moves through space toward the constellation Hercules.

Alexander Bickerton suggested in 1880 that planets formed when a passing star pulled material out of the sun. The sun and surrounding stars orbit the galactic nucleus in stable, nearly circular paths, minimizing collision risks. The sun takes about 200 million years to complete one revolution and has completed roughly 25 circuits without major mishap.

Direct collisions or close approaches between stars in the galactic outskirts are extremely improbable. The chance of any two stars having a near approach is estimated at no more than 1 in 5 million over the 15-billion-year history of the Galaxy, translating to a 1-in-80,000 chance over the next trillion years. Globular clusters cross the galactic plane periodically every 500,000 years on average, but present a negligible collision threat.

Single-star black holes without companion stars emit minimal radiation and are extremely rare. Stephen Hawking suggested in 1974 that the Big Bang produced numerous sub-stellar mini-black holes that slowly evaporate. Antimatter consists of antiparticles that annihilate ordinary matter upon contact, converting 100 percent of mass into energy. Sub-stellar bodies that formed independently without circling a star may wander freely through the Galaxy.

6. The Death of the Sun

In 1854, Helmholtz proposed that the sun is steadily contracting under its own gravity, converting inward-falling motion into radiation, which meant the sun had a definite beginning and would eventually run out of energy. This implied a limited 25 million years of solar output. Antoine Henri Becquerel discovered radioactivity in 1896. Hans Bethe showed in 1938 that hydrogen fusion powers the sun's core, allowing it to shine steadily for nearly 5 billion years. The sun consists of 75 per cent hydrogen and 25 per cent helium by mass.

The sun is powered by hydrogen fusion which will eventually exhaust its core fuel, causing it to expand into a red giant before collapsing into a white dwarf.

As core hydrogen converts to helium, the core grows denser and hotter, initiating helium fusion into heavier elements. This overbalances equilibrium toward expansion, increasing the sun's total radiated energy over a vast surface area that glows red instead of white.

Betelgeuse in Orion and Antares in Scorpio are examples of red giant stars.

The sun has a maximum remaining time of 7 billion years as a life-giving sun for Earth. Its present diameter will expand by a factor of 100 during red gianthood, engulfing Mercury and Venus. Before the sun's expansion vaporizes Earth, you could escape by establishing civilizations on outer planet satellites or artificial space settlements. With billions of years of warning, humanity could terra-form outer satellites like Ganymede and Callisto or build self-contained, mobile space settlements capable of adjusting their orbits as the sun changes. Such proposed artificial space settlements have a population capacity of 10,000 to 10 million human beings.

When fusion ceases to hold back gravity, stars collapse. Small stars contract into dense white dwarfs supported by an electron gas, while extremely massive stars explode violently in supernovas or collapse into neutron stars or black holes. A white dwarf sun has 1/4000 of the brightness of the present sun as viewed from Jupiter satellites, and an absolute minimum mass 1.4 times as massive as the sun is required for a star to become a supernova.

Supernovas like those recorded in 1054, 1006, 1572, and 1604, as well as the nearby Vela supernova remnant, released high-energy X-rays and cosmic rays, but Earth's atmosphere protected life from destruction.

The supernova of 1054 was recorded by Chinese astronomers on 4 July, 1054 in Taurus and exceeded Venus in brightness, leaving behind the 13 light-years Crab nebula. The Gum nebula centre is located at a distance of 1500 light-years from Earth, and a supernova may explode within 100 light-years of Earth at an average interval of 750 million years.

Heinrich Schwabe announced the sunspot cycle in 1843, and George Ellery Hale identified associated magnetic fields. Sunspots follow cyclic patterns of magnetic activity, including extended periods of inactivity known as Maunder minima.

The period from 1645 to 1715, when sunspot observations and auroras nearly ceased, is known as the Maunder minimum, while in 1959 the Zürich sunspot number reached an all-time high of 200.

Solar neutrino detection experiments revealed far fewer neutrinos than predicted by standard models of the sun's core. Raymond Davis, Jr. used 378,000 litres or 100,000 gallons of tetrachloroethylene cleaning fluid 1.5 kilometres or 1 mile deep in the Homestake gold mine in Lead, South Dakota, to detect argon atoms produced by solar neutrinos, but found only a fraction of the expected number, indicating that current theories of stellar cores require revision. Neutrinos take 2.3 seconds to reach the sun's surface from its core, and 500 seconds to reach Earth from the sun, compared to photons.

7. The Bombardment of the Earth

Earth remains vulnerable to extraterrestrial impacts from comets and Earth-grazing asteroids, but future space observation and defense can prevent such disasters.

An invading mini-black hole of asteroidal size could tunnel through the Earth, causing massive explosions and potentially consuming the planet from the core outward. A small mini-black hole would tunnel into the Earth's crust, melting and vaporizing matter ahead of it. With low momentum, it could get trapped by Earth's gravity, oscillating through the interior and creating a growing hollowed-out region until the planet collapses and is consumed. This measures 2 centimetres (0.8 inches) across in size for the resulting Earth-mass black hole, representing catastrophes of the third class.

The 1908 Tunguska explosion in Siberia was likely caused by a small, icy comet that vaporized and exploded violently in the atmosphere before reaching the ground. Astronomers believe the devastation was caused by a small comet whose icy material evaporated so rapidly during its atmospheric plunge that it exploded shatteringly about 10 kilometers above ground, leaving no impact crater or surface fragments.

On 30 June 1908 on the Tunguska River, a huge explosion knocked down every tree for a score of miles and wiped out a reindeer herd without leaving a crater. This occurred on 30 June 1908, with the explosion estimated at 10 kilometres (6 miles) above ground.

Earth-grazing asteroids whose orbits bring them close to our planet represent a continuous hazard capable of city-destroying impacts. Numerous asteroids have elliptical orbits that bring them inside the asteroid belt and close to Earth's orbit. Due to the difficulty of spotting them in advance, these mountain- or boulder-sized bodies pose a significant risk of sudden, unannounced impacts. Astronomers have located and calculated 1700 such objects, while estimating a total of 40,000 to 100,000 asteroids with diameters over a kilometre.

In November 1937, an asteroid named Hermes passed Earth at a distance of no more than 800,000 kilometres. This closest observed distance of Hermes measured 800,000 kilometres (500,000 miles).

Ancient impact scars called fossil craters have been eroded over millennia by wind, water, and life, leaving behind circular geological formations. Large meteorites that struck Earth in the distant past buried themselves deep or left massive craters that were subsequently eroded away by surface processes. Only circular, water-filled depressions reveal the evidence of these prehistoric strikes.

The Ungava-Quebec crater in Canada was discovered in 1950 from aerial photographs showing a circular lake surrounded by smaller circular lakes. This site measures 3.34 kilometres (2.07 miles) in diameter and 0.361 kilometres (401 feet) in depth, while Meteor Crater in Arizona spans 1.2 kilometres (0.75 miles) across.

Advanced space observatories and targeted counterattacks could soon make meteor strikes a preventable disaster. With space-based observatories free from atmospheric interference, astronomers will be able to detect smaller Earth-grazers in advance and plot their orbits precisely, allowing future space missions to intercept and vaporize dangerous rocks into harmless pebble showers.

You can prevent meteor disasters by following these steps:

• Establish elaborate astronomical observatories on the moon and in Earth orbit without an interfering atmosphere
• Watch dangerous Earth-grazers closely and plot their orbits more carefully
• Send some powerful device to intersect the dangerous rock at a precalculated position in space and blow it up

8. The Slowing of the Earth

Tidal friction continuously slows the Earth's rotation and forces the moon to recede to conserve angular momentum.

As the Earth turns through the tidal bulges created primarily by the moon, frictional resistance converts rotational energy into heat. This causes the Earth's speed of rotation to decrease continuously, making days slowly grow longer at the current rate of 1 second every 62,500 years.

In 1963, paleontologist John West Wells studied fossil corals from 400 million years ago and found about 400 fine daily markings to every coarser yearly marking, indicating a 21.9-hour day and 395 days in a year.

9. The Drift of the Crust

Internal radioactivity drives plate tectonics, continental drift, and sea-floor spreading, generating earthquakes and volcanic eruptions that pose local rather than global risks.

The Earth's interior remains intensely hot due to primordial kinetic energy and the ongoing radioactive breakdown of specific long-lived atoms. Center temperatures are estimated as high as 2700°C. Uranium-238, uranium-235, thorium-232, and potassium-40 generate heat that matches the heat lost from the surface.

Alfred Wegener published The Origin of Continents and Oceans in 1912. Harry Hammond Hess presented evidence in favour of sea-floor spreading in 1960. Plates are pushed apart in some places at a rate of 2 to 18 centimetres a year.

Volcanoes and earthquakes are localized crustal hazards. There are 455 known active volcanoes in the world erupting into the atmosphere. The Minoan civilization was destroyed around 1470 BC when the volcanic island of Thira exploded with a force five times greater than Krakatoa.

You can anticipate earthquakes and minimize hazards by using specific precautions:

• Monitor delicate changes in local magnetic, electrical, and gravitational fields.
• Track day-to-day changes in the level and chemical content of well-water.
• Observe properties of the air and radon gas levels.
• Drill deep wells several kilometres apart along fault lines to force water in and relieve subterranean pressures.

10. The Change of Weather

Johann H. Charpentier and J. Venetz discovered that Alpine glaciers were once much larger. Jean L. R. Agassiz tested this in 1839 by hammering stakes 6 metres into the ice, and by the summer of 1841, he found they had moved in a shallow U shape.

A small initial cooling in summer can trigger a self-amplifying feedback loop where accumulating snow turns to ice and reflects more sunlight, eventually building massive ice sheets.

Ice reflects roughly 90 percent of incoming light compared to less than 10 percent for bare soil. Carbon dioxide and water vapour act as conservers of heat through the greenhouse effect by blocking outgoing infrared radiation while remaining transparent to visible light. The atmosphere currently contains 0.03 percent carbon dioxide.

Milutin Milankovich proposed that a Great Winter and Great Summer cycle results from orbital variations. J. D. Hays, John Imbrie, and N. J. Shackleton analyzed Indian Ocean sediment cores in December 1976 to confirm a climate cycle matching orbital calculations. Plate tectonics also arranges landmasses around a nearly landlocked polar body like the Arctic Ocean to trigger major continental glaciation.

Future glaciations would not necessarily be catastrophic because glaciers advance extremely slowly. At the height of glaciation, 30 percent of Earth's land surface was covered by ice, and sea levels dropped 150 metres. Humanity's advancing technology could regulate atmospheric carbon dioxide or use space mirrors to counteract unwanted temperature shifts.

11. The Removal of Magnetism

William Gilbert suggested in 1600 that Earth was a huge magnet. Walter Elsasser suggested in 1939 that rotation-driven swirls in the liquid nickel-iron core generate electromagnetism.

Earth's magnetic field periodically weakens and reverses direction, while cosmic rays and genetic mutations shape biological evolution.

Bernard Brunhes noticed in 1906 that some volcanic rock-crystals were magnetized in the reverse direction. The magnetic field has been in its present normal direction for 700,000 years. The average length of time between magnetic reversals is 450,000 years.

During reversals, the magnetosphere collapses temporarily and increases the flux of cosmic rays. Victor Francis Hess discovered in 1911 via balloon experiments that penetrating radiation increased with height. Robert Andrews Millikan named cosmic rays in 1925.

Deoxyribonucleic acid serves as the complex chemical blueprint within chromosomes. Oswald Avery showed in 1944 that the blueprint molecule is DNA. James Watson and Francis Crick worked out the double helix structure of DNA in 1953.

Mutations are imperfect replications of DNA that generally cause harm. Seth Wright bred a line of short-legged sheep in 1791 after a lamb was born with a mutation. Hermann Muller demonstrated in 1926 that X-rays increase mutation rates in fruit flies.

12. The Competition of Life

Catastrophes of the fourth class threaten human life specifically while life generally continues on Earth, unlike cosmic or planetary disasters. High reproductive rate, or fecundity, is far more effective for long-term species survival than high intelligence.

While small pests, insects, and infectious diseases pose severe biological challenges, human medical science and hygiene provide robust defenses.

Humanity has virtually destroyed many large species while failing to make a dent in the Norway rat population. A single pair can produce 219,660 rats in three generations over about nine years. Insects comprise 700,000 known species out of 3 million estimated total insect species, with 250 million insects for each human being. They cause 8 billion dollars in annual insect damage in the United States. Red cotton bugs destroy half of all cotton grown in India each year, and the boll weevil causes massive losses in the United States.

Humanity's war against small pests evolved from mineral poisons to organic pesticides and finally to biological controls and modern integrated methods. The 1877 introduction of copper, lead, and arsenic compounds as insect poisons gave way to Paul Muller discovering the insecticidal properties of DDT in September 1939. Following the 1962 publication of Silent Spring by Rachel Carson, control methods shifted.

Infectious disease spread by crowding has come closer to destroying the human species than any animal depredations. In 430 BC a plague killed 20 percent of Athens. The bubonic plague in 541 AD killed one-third to one-half of Constantinople, and the Black Death in the 14th century killed an estimated third of the human population of the planet, approximately 60 million people or more. The 1918 Spanish influenza killed 30 million people worldwide in one year.

The establishment of the germ theory of disease and subsequent medical breakthroughs provided humanity with rational defenses. Edward Jenner demonstrated smallpox vaccination using cowpox in 1798. Ignaz Semmelweiss enforced handwashing to drop childbed fever rates in 1847. Louis Pasteur linked silkworm disease to parasites in 1865. The Salk polio vaccine arrived in 1955.

You can apply these protective measures:

• wash hands before attending women in childbirth to prevent childbed fever;
• destroy all infested worms and food in silkworm disease outbreaks;
• surgeons wash hands in bacteria-killing chemical solutions before operating;
• practice personal hygiene, careful waste disposal, and food and water cleanliness;
• sterilize objects sent to other planets to minimize spreading earthly microorganisms;
• place astronauts in quarantine after returning from the moon.

Svante Arrhenius suggested in 1908 that bacterial spores might be wafted into space and seed other planets through panspermia and radiation pressure. Earth passage through the tail of Halley's comet in 1910 sparked similar concerns over new disease, but ultraviolet radiation destroys exposed spores and microorganisms require specific adaptation to parasitize human hosts.

13. The Conflict of Intelligence

Human intelligence introduces strategic warfare and historical conflicts, culminating in the existential peril and deterrence of the nuclear age.

Animals fight without foresight, but increasing intelligence brings memory and planning. Victors calculate the advantage of killing rivals, while losers seek strategic reinforcements.

The development of herding and agriculture around 7000 BC allowed higher population densities and static property. This fostered social cooperation, specialized labor, and defensive walled cities around 3500 BC that marked the birth of civilization.

Nomadic barbarians attacked during periods of internal civilized decay, causing temporary dark ages. Gutian barbarians controlled the Tigris-Euphrates valley around 2180 BC, and the western Roman Empire fell after the Gothic victory at Adrianople in AD 378. Genghis Khan united Mongol tribes in 1206 to build the largest continuous land empire in history.

The invention of gunpowder and development of artillery permanently shifted the military balance to civilization. In the nuclear age, catastrophic weapon destructiveness creates a genuine risk of species suicide. The Cuban Missile Crisis from October 22 to October 28, 1962, brought the world to the brink of nuclear war before Soviet missiles left Cuba.

14. The Depletion of Resources

Unlike all other life forms which deal exclusively with indefinitely renewable resources, humans alone rely on nonrenewable resources, creating the risk of sudden technological and civilizational collapse. Green plants, animals, and inanimate elements like fresh water, wind, and tides operate in infinite cycles sustained by solar radiation.

Industrial civilization depends on nonrenewable material and energy resources, requiring a transition to nuclear fusion and sustainable energy sources.

Around 2500 BC, Middle Eastern civilizations completely exhausted local supplies of tin, forcing Phoenician navigators to search for new sources all the way to the Tin Isles off Cornwall. Thorstein Veblen coined the phrase conspicuous consumption in 1899 to describe the use of waste as a sign of social success. Energy is the ultimate resource because continuous energy is required to power recycling, extract dilute minerals, and neutralize environmental pollution. Edwin Laurentine Drake successfully drilled the first productive oil well in Titusville, Pennsylvania, in 1859, launching the modern petroleum industry.

The earth holds 350 billion barrels of petroleum mined since Drake's well, with an estimated 660 billion barrels left in the ground. At current consumption rates, remaining oil will last 33 years, while atmospheric carbon dioxide has risen from 0.029 per cent to 0.032 per cent since 1900.

15. The Dangers of Victory

Geometric population growth, thermal pollution, and technological hubris threaten human survival unless managed through rational global cooperation.

Human population increase is a geometric progression that will inevitably outpace any conceivable technological advance if left unchecked. A steady 2 percent annual growth rate would cause the total mass of human flesh and blood to equal the mass of the Earth in 1,800 years and the mass of the entire universe in a little over 5,000 years. In 1800 with a population of 1 billion and a 0.5 percent growth rate, 5 million new mouths were added yearly, whereas in the 1970s with 4 billion people and a 2 percent growth rate, 80 million new mouths were added annually.

All potential catastrophes can be divided into probable or inevitable events and extremely unlikely events. Probable catastrophes are subdivided into those looming in the immediate future and those occurring far in the future. Immediate probable catastrophes are divided into those that can be avoided and those that cannot, with none falling into the unavoidable category.

You can avoid all imminent catastrophes by taking decisive steps:

• Behave rationally and humanely.
• Concentrate coolly on problems facing all of humanity.
• Abandon emotional matters like national security and local pride.
• Recognize that neighbors are not the enemy, but misery, ignorance, and the cold indifference of natural law are.

By avoiding catastrophes over the next century, you can help humanity spread into space, lose its vulnerabilities, and outlast the Earth and the sun.

10 Key Ideas

1. Isaac Asimov analyzes potential existential and civilizable threats to humanity, dividing perils into classes ranging from universal destruction to the collapse of civilization.
2. The second law of thermodynamics governs all physical change by ensuring that entropy in the universe constantly increases toward an ultimate heat-death.
3. The sun is powered by hydrogen fusion which will eventually exhaust its core fuel, causing it to expand into a red giant before collapsing into a white dwarf.
4. Earth remains vulnerable to extraterrestrial impacts from comets and Earth-grazing asteroids, but future space observation and defense can prevent such disasters.
5. Internal radioactivity drives plate tectonics, continental drift, and sea-floor spreading, generating earthquakes and volcanic eruptions that pose local rather than global risks.
6. A small initial cooling in summer can trigger a self-amplifying feedback loop where accumulating snow turns to ice and reflects more sunlight, eventually building massive ice sheets.
7. While small pests, insects, and infectious diseases pose severe biological challenges, human medical science and hygiene provide robust defenses.
8. Human intelligence introduces strategic warfare and historical conflicts, culminating in the existential peril and deterrence of the nuclear age.
9. Industrial civilization depends on nonrenewable material and energy resources, requiring a transition to nuclear fusion and sustainable energy sources.
10. Geometric population growth, thermal pollution, and technological hubris threaten human survival unless managed through rational global cooperation and space expansion.