Developments in brief

Wars and politics

• After decades of struggle by the women's suffrage movement, all western countries gave women the right to vote.
• Rising nationalism and increasing national awareness were among the many causes of World War I (1914–1918), the first of two wars to involve many major world powers including Germany, France, Italy, Japan, Russia/USSR, the United States and the British Empire. World War I led to the creation of many new countries, especially in Eastern Europe. At the time it was said by many to be the "war to end all wars".

Warfare in the early 20th Century (1914–1918)
Clockwise from top: front line Trenches, a British Mark I Tank crossing a trench, the Royal Navy battleship HMS Irresistible sinking after striking a mine at the battle of the Dardanelles, a Vickers machine gun crew with gas masks, and German Albatros D.III biplanes.

• Civil wars occurred in many nations. A violent civil war broke out in Spain in 1936 when General Francisco Franco rebelled against the Second Spanish Republic. Many consider this war as a testing battleground for World War II, as the fascist armies bombed some Spanish territories.
• The economic and political aftermath of World War I and the Great Depression in the 1930s led to the rise of fascism and nazism in Europe, and subsequently to World War II (1939–1945). This war also involved Asia and the Pacific, in the form of Japanese aggression against China and the United States. Civilians also suffered greatly in World War II, due to the aerial bombing of cities on both sides, and the German genocide of the Jews and others, known as the Holocaust. In 1945, Hiroshima and Nagasaki were bombed with nuclear weapons.
• During World War I, in Russia the Bolshevik putsch took over the Russian Revolution of 1917, precipitating the founding of the Soviet Union and the rise of communism. After the Soviet Union's involvement in World War II, communism became a major force in global politics, notably in Eastern Europe, China, Indochina and Cuba, where communist parties gained near-absolute power. This led to the Cold War and proxy wars with the West, including wars in Korea (1950–1953) and Vietnam (1957–1975).
• The Soviet authorities caused the deaths of millions of their own citizens in order to eliminate domestic opposition. More than 18 million people passed through the Gulag, with a further 6 million being exiled to remote areas of the Soviet Union.^[1][2]
• The civil rights movement in the United States and the movement against apartheid in South Africa challenged racial segregation in those countries.
• The two world wars led to efforts to increase international cooperation, notably through the founding of the League of Nations after World War I, and its successor, the United Nations, after World War II.
• The creation of Israel, a Jewish state in the Middle East, by the British Mandate of Palestine fueled many regional conflicts. These were also influenced by the vast oil fields in many of the other countries of the mostly Arab region.
• The end of colonialism led to the independence of many African and Asian countries. During the Cold War, many of these aligned with the United States, the USSR, or China for defense.
• After a long period of civil wars and conflicts with European powers, China's last imperial dynasty ended in 1912. The resulting republic was replaced, after yet another civil war, by a communist People's Republic in 1949. At the end of the century, though still ruled by a communist party, China's economic system had transformed almost completely to capitalism.
• The Great Chinese Famine was a direct cause of the death of tens of millions of Chinese peasants between 1959 and 1962. It is thought to be the largest famine in human history.
• The Tiananmen Square protests of 1989, culminating in the deaths of hundreds of civilian protestors, were a series of demonstrations in and near Tiananmen Square in Beijing,China. Led mainly by students and intellectuals, the protests occurred in a year that saw the collapse of a number of communist governments around the world.
• The revolutions of 1989 released Eastern and Central Europe from Soviet supremacy. Soon thereafter, the Soviet Union, Czechoslovakia, and Yugoslavia dissolved, the latter violently over several years, into successor states, many rife with ethnic nationalism. East Germany and West Germany were reunified in 1990.
• European integration began in earnest in the 1950s, and eventually led to the European Union, a political and economic union that comprised 15 countries at the end of the century.

Culture and entertainment

• As the century began, Paris was the artistic capital of the world, where both French and foreign writers, composers and visual artists gathered.
• Movies, music and the media had a major influence on fashion and trends in all aspects of life. As many movies and much music originate from the United States, American culture spread rapidly over the world.
• Computer games and internet surfing became new and popular form of entertainment during the last 25 years of the century.
• In literature, science fiction, fantasy (with well developed, rich in detail fictional worlds), alternative history fiction gained unprecedented popularity. Detective fiction gained unprecedented popularity between the two world wars.
• Blues and jazz music became popularized during the 1910s and 1920s in the United States. Blues went on to influence rock and roll in the 1950s, which only increased in popularity with the British Invasion of the mid-to-late '60s. Rock soon branched into many different genres, including heavy metal, punk rock, and alternative rock and became the dominant genre of popular music. This was challenged with the rise of hip hop in the 1980s and 1990s. Other genres such as house, techno, reggae, and soul all developed during the latter half of the 20th century and went through various periods of popularity.

I and the Village by Marc Chagall, a modern painter.

• In classical music, composition branched out into many completely new domains, including dodecaphony, aleatoric (chance) music, and minimalism.
• Synthesizers began to be employed widely in music and crossed over into the mainstream with new wave music in the 1980s. Electronic instruments have been widely deployed in all manners of popular music and has led to the development of such genres as house, synthpop, electronic dance music, and industrial.
• The art world experienced the development of new styles and explorations such as expressionism, Dadaism, cubism, de stijl, abstract expressionism and surrealism.
• The modern art movement revolutionized art and culture and set the stage for both Modernism and its counterpart postmodern art as well as other contemporary art practices.
• In Europe, modern architecture departed radically from the excess decoration of the Victorian era. Streamlined forms inspired by machines became more commonplace, enabled by developments in building materials and technologies. Before World War II, many European architects moved to the United States, where modern architecture continued to develop.
• After gaining political rights in the United States and much of Europe in the first part of the century, and with the advent of new birth control techniques, women became more independent throughout the century.
• The automobile vastly increased the mobility of people in the Western countries in the early to mid-century, and in many other places by the end of the century. City design throughout most of the West became focused on transport via car.
• The popularity of sport increased considerably—both as an activity for all, not just the elite, and as entertainment, particularly on television.

Science

• Starting with invention of Turing machine, new fields of mathematics studying computability and computation complexity were developed.
• Gödel's incompleteness theorems were formulated and proven.
• New areas of physics, like special relativity, general relativity, and quantum mechanics, were developed during the first half of the century.
• While some pioneering experiments about internal structure of atoms had been made at the end of XIX century, it is only in XX century the structure of atoms was clearly understood, followed by discovery of elementary particles.
• It was found that all the known forces can be traced to only four fundamental interactions. It was discovered further that two of them, namely electromagnetism and weak interaction, can be merged in the electroweak interaction, leaving only three different fundamental interactions.
• Discovery of nuclear reactions, in particular nuclear fusion, finally solved the problem of the source of solar energy. The age of solar system, including Earth, was determined and it turned to be much older than what was considered before (more than 4 billions years rather than 20 millions years suggested by lord Kelvin in 1862^[3]).
• Radiocarbon dating became a powerful technique to determine the age of prehistoric animals and plants as well as historical objects. No such technique existed in XIX century.
• In astronomy, much better understanding of the evolution of the Universe was achieved, its age was determined, the Big Bang theory was proposed. Planets of solar system and their moons were closely discovered. It was found that there is no sentient (or complex animal or plant) life on their surface.
• In biology, genetics was unanimously accepted and significantly developed. The structure of DNA was determined in 1953 by Watson and Criek, following by developing techniques which allow to read DNA sequences and culminating in starting the Human Genome Project (not finished in XX century) and cloning the first mammal in 1996.
• The role of sex reproduction in evolution was understood, and bacterial conjugation was discovered.

Technology

• The number and types of home appliances increased dramatically due to advancements in technology, electricity availability, and increases in wealth and leisure time. Such basic appliances as washing machines, clothes dryers, exercise machines, refrigerators, freezers, electric stoves, and vacuum cleaners all became popular from the 1920s through the 1950s. The microwave oven became popular during the 1980s. Radios were popularized as a form of entertainment during the 1920s, which extended to television during the 1950s. Cable television spread rapidly during the 1980s. Personal computers began to enter the home during the 1970s-1980s as well. The age of the portable music player grew during the 1960s with the development of 8-track and cassette tapes, which slowly began to replace record players. These were in turn replaced by the CD during the late 1980s and 1990s. The proliferation of the Internet in the mid-to-late 1990s made digital distribution of music (mp3s) possible. VCRs were popularized in the 1970s, but by the end of the millennium, DVDs were beginning to replace them.
• The first airplane was flown in 1903. With the engineering of the faster jet engine in the 1940s, mass air travel became commercially viable.
• The assembly line made mass production of the automobile viable. By the end of the century, billions of people had automobiles for personal transportation. The combination of the automobile, motor boats and air travel allowed for unprecedented personal mobility. In western nations, motor vehicle accidents became the greatest cause of death for young people. However, expansion of divided highways reduced the death rate.
• The triode tube (Audion), transistor and integrated circuit revolutionized computers, leading to the proliferation of the personal computer in the 1980s and cell phones and the public-use Internet in the 1990s.
• New materials, most notably plastics, polyethylene, Velcro, and teflon, came into widespread use for many various applications.
• Thousands of chemicals were developed for industrial processing and home use.
• The Space Race between the United States and the Soviet Union gave a peaceful outlet to the political and military tensions of the Cold War, leading to the first human spaceflight with the Soviet Union's Vostok 1 mission in 1961, and man's first landing on another world—the Moon—with America's Apollo 11 mission in 1969. Later, the first space station was launched by the Soviet space program. The United States developed the first (and to date only) reusable spacecraft system with the Space Shuttle program, first launched in 1981. As the century ended, a permanent manned presence in space was being founded with the ongoing construction of the International Space Station.
• In addition to Human spaceflight, unmanned space probes became a practical and relatively inexpensive form of exploration. The first orbiting space probe, Sputnik 1, was launched by the Soviet Union in 1957. Over time, a massive system of artificial satellites was placed into orbit around Earth. These satellites greatly advanced navigation, communications, military intelligence, geology, climate, and numerous other fields. Also, by the end of the century, unmanned probes had visited the Moon, Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune, and various asteroids and comets. The Hubble Space Telescope, launched in 1990, greatly expanded our understanding of the Universe and brought brilliant images to TV and computer screens around the world.

Medicine

• Placebo-controlled, randomized, blinded clinical trials became a powerful tool for testing new medicines.
• Antibiotics drastically reduced mortality from bacterial diseases and their prevalence.
• A vaccine was developed for polio, ending a worldwide epidemic. Effective vaccines were also developed for a number of other serious infectious diseases, including influenza, diphtheria, pertussis (whooping cough), tetanus, measles, mumps, rubella (German measles), chickenpox, hepatitis A, and hepatitis B.
• A successful application of epidemiology and vaccination led to the eradication of the smallpox virus in humans.
• X-rays became powerful diagnostic tool for wide spectrum of diseases, from bone fractures to cancer. In the 1960s, computerized tomography was invented. Other important diagnostic tools developed were sonography and magnetic resonance imaging.
• Development of vitamins virtually eliminated scurvy and other vitamin-deficiency diseases from industrialized societies.
• New psychiatric drugs were developed. These include antipsychotics for treating hallucinations and delusions, and antidepressants for treating depression.
• The role of tobacco smoking in the causation of cancer and other diseases was proven during the 1950s (see British Doctors Study).
• New methods for cancer treatment, including chemotherapy, radiation therapy, and immunotherapy, were developed. As a result, cancer could often be cured or placed in remission.
• The development of blood typing and blood banking made blood transfusion safe and widely available.
• The invention and development of immunosuppressive drugs and tissue typing made organ and tissue transplantation a clinical reality.
• Research on sleep and circadian rhythms led to the discovery of sleep disorders.
• New methods for heart surgery were developed, including pacemakers and artificial hearts.
• Cocaine/crack and heroin were found to be dangerous addictive drugs, and their wide usage had been outlawed; mind-altering drugs such as LSD and MDMA were discovered and later outlawed. In many countries, a war on drugs caused prices to soar 10x-20x higher, leading to profitable black market drugdealing, and to prison inmate sentences being 80% related to drug use by the 1990s.
• Contraceptive drugs were developed, which reduced population growth rates in industrialized countries.
• The development of medical insulin during the 1920s helped raise the life expectancy of diabetics to three times of what it had been earlier.
• The elucidation of the structure and function of DNA initiated the development of genetic engineering and the mapping of the human genome.
• Masturbation was found to be a harmless activity. Beliefs that it seriously harms physical and mental health, shared by XIX century physicians, found to be wrong. ^[4]
• As a result of some of the above developments, most notably antibiotics and vaccines, child and young people's mortality decreased drastically.

Notable diseases

• An influenza pandemic, the Spanish Flu, killed anywhere from 20 to 100 million people between 1918 and 1919.
• A new viral disease, AIDS, arose in Africa and subsequently killed millions of people throughout the world. AIDS treatments remained inaccessible to many people living with AIDS in developing countries, and a cure has yet to be discovered.
• Because of increased life spans, the prevalence of cancer, Alzheimer's disease, Parkinson's disease, and other diseases of old age increased slightly.
• Sedentary lifestyles, due to labor-saving devices and technology, contributed to an "epidemic" of obesity, at first in the rich countries, but by the end of the century, increasingly in the developing world, too.

Energy and the environment

Oil field in California, 1938 The first modern oil well was drilled in 1848 by Russian engineer F.N. Semyonov, on the Apsheron Peninsula north-east of Baku.

• The dominant use of fossil sources and nuclear power, considered the conventional energy sources.
• Widespread use of petroleum in industry—both as a chemical precursor to plastics and as a fuel for the automobile and airplane—led to the vital geopolitical importance of petroleum resources. The Middle East, home to many of the world's oil deposits, became a center of geopolitical and military tension throughout the latter half of the century. (For example, oil was a factor in Japan's decision to go to war against the United States in 1941, and the oil cartel, OPEC, used an oil embargo of sorts in the wake of the Yom Kippur War in the 1970s).
• A vast increase in fossil fuel consumption caused smog and other forms of air pollution, global warming, local and global climate change.
• Pesticides, herbicides and other toxic chemicals accumulated in the environment, including the bodies of humans and other animals.
• Overpopulation and worldwide deforestation diminished the quality of the environment.
• Rapidly falling fertility rates among Americans and Europeans begin to cause what has been called a "demographic winter," with a possibility of soon bringing these cultures to an end forever. ^[5]

The world at the end of the century

By the end of the 20th century, more technological advances had been made than in all of preceding history. Communications and information technology, transportation technology, and medical advances had radically altered daily lives. Europe appeared to be at a sustainable peace for the first time in recorded history. The people of the Indian subcontinent, a sixth of the world population at the end of the century, had attained an indigenous independence for the first time in centuries. China, an ancient nation comprising a fifth of the world population, was finally open to the world in a new and powerful synthesis of west and east, creating a new state after the near-complete destruction of the old cultural order. With the end of colonialism and the Cold War, nearly a billion people in Africa were left with truly independent new nation states, some cut from whole cloth, standing up after centuries of foreign domination.

The world was undergoing its second major period of globalization; the first, which started in the 18th century, having been terminated by World War I. Since the U.S. was in a position of almost unchallenged domination, a major part of the process was Americanization. This led to anti-Western and anti-American feelings in parts of the world, especially the Middle East. The influence of China and India was also rising, as the world's largest populations, long marginalized by the West and by their own rulers, were rapidly integrating with the world economy.

Terrorism, dictatorship, and the spread of nuclear weapons were some issues requiring attention. The world was still blighted by small-scale wars and other violent conflicts, fueled by competition over resources and by ethnic conflicts. Despots such as Kim Jong-il of North Korea continued to lead their nations toward the development of nuclear weapons.

Disease threatened to destabilize many regions of the world. New viruses such as SARS and West Nile continued to spread. Malaria and other diseases affected large populatios. Millions were infected with HIV, the virus which causes AIDS. The virus was becoming an epidemic in southern Africa.

The geographic distribution of surface warming during the 21^st century calculated by the HadCM3 climate model if a business as usual scenario is assumed for economic growth and greenhouse gas emissions. In this figure, the globally averaged warming corresponds to 3.0 °C (5.4 °F).

Some speculate that in the long term, environmental problems may threaten the planet's liveability. One popular belief is that global warming may be occurring, and may be due to human-caused emission of greenhouse gases, particularly carbon dioxide produced by the burning of fossil fuels. This prompted many nations to negotiate and sign the Kyoto treaty, which set mandatory limits on carbon dioxide emissions.

World population

Some believe that significant driver of many of the problems at the end of the 20th century was overpopulation. Yet the 20th century is most notable for the sheer numbers of mass genocide and the killing of over 262 million people by government. See, for example, "Power Kills" and updated statistics for 1900-1999 at the University of Hawaii. Government action, rather than economic or social conditions, or even international conflict and war, were the driving causes of death in the 20th Century.

Overpopulation has been a fascination of many including economic theorist Reverend Thomas Robert Malthus whose "An Essay on the Principal of Population" was first published in 1798. At the century's end, the global population was 6.1 billion and rising. In the long term, it was predicted that the population would probably reach a plateau of nine billion around 2050.