20th century Warning: You are not logged in. Your IP address will be publicly visible if you make any edits. If you log in or create an account, your edits will be attributed to your username, along with other benefits.Anti-spam check. Do not fill this in! == Science == {{main|20th century in science}} {{see also|Big Science}} === Mathematics === [[File:Alan Turing portré.jpg|thumb|upright|The pioneer of [[computer science]], [[Alan Turing]]]] Multiple new fields of mathematics were developed in the 20th century. In the first part of the 20th century, [[measure theory]], [[functional analysis]], and [[topology]] were established, and significant developments were made in fields such as [[abstract algebra]] and [[probability]]. The development of [[set theory]] and [[formal logic]] led to [[Gödel's incompleteness theorems]]. Later in the 20th century, the development of computers led to the establishment of a [[theory of computation]].<ref name="BoyerMath">{{Cite book|title=A history of mathematics|last=Boyer|first=Carl B.|date=1991|publisher=Wiley|others=[[Uta Merzbach|Merzbach, Uta C.]], 1933–, Rogers D. Spotswood Collection.|isbn=978-0471543978|edition=2nd ed. [rev.]|location=New York|oclc=23823042|url=https://archive.org/details/historyofmathema00boye}}</ref> Computationally-intense results include the study of [[fractal]]s<ref>{{cite book|last1=Devaney|first1=Robert L.|title=A first course in chaotic dynamical systems : theory and experiment|date=1998|publisher=Addison-Wesley|location=Reading, Mass. [u.a.]|isbn=978-0-201-55406-9|edition=6. printing.}}</ref> and a proof of the [[four color theorem]] in 1976.<ref>{{Cite journal|title=Every Planar Map is Four-Colorable|date=26 July 1976|journal=Bulletin of the American Mathematical Society|author1=Kenneth Appel|author2-link=Wolfgang Haken|author2=Wolfgang Haken |series=Contemporary Mathematics|volume=98|doi=10.1090/conm/098|isbn=9780821851036|s2cid=8735627|url=http://projecteuclid.org/euclid.bams/1183538218|author1-link=Kenneth Appel}}</ref> === Physics === * New areas of [[physics]], like [[special relativity]], [[general relativity]], and [[quantum mechanics]], were developed during the first half of the century. In the process, the internal structure of [[atom]]s came to be clearly understood, followed by the discovery of [[elementary particle]]s. * It was found that all the known [[force]]s can be traced to only four [[fundamental interaction]]s. It was discovered further that two forces, [[electromagnetism]] and [[weak interaction]], can be merged in the [[electroweak interaction]], leaving only three different fundamental interactions. * Discovery of [[nuclear reaction]]s, in particular [[nuclear fusion]], finally revealed the source of [[sun|solar]] energy. * [[Radiocarbon dating]] was invented, and became a powerful technique for determining the age of [[Prehistory|prehistoric]] animals and plants as well as historical objects. === Astronomy === * A much better understanding of the evolution of the [[universe]] was achieved, its [[Age of the universe|age]] (about 13.8 billion years) was determined, and the [[Big Bang]] theory on its origin was proposed and generally accepted. * The age of the [[Solar System]], including Earth, was determined, and it turned out to be much older than believed earlier: more than 4 billion years, rather than the 20 million years suggested by [[Lord Kelvin]] in 1862.<ref>{{cite journal |last=Thomson |first=Sir William |title=On the Age of the Sun's Heat |journal=Macmillan's Magazine |year=1862 |volume=5 |pages=288–293 |url=http://zapatopi.net/kelvin/papers/on_the_age_of_the_suns_heat.html}}</ref> * The planets of the Solar System and their moons were closely observed via numerous [[space probe]]s. [[Pluto]] was discovered in 1930 on the edge of the Solar System, although in the early 21st century, it was reclassified as a [[dwarf planet]] instead of a planet proper, leaving eight planets. * No trace of life was discovered on any of the other planets orbiting [[Sun|the Sun]] (or elsewhere in the universe), although it remained undetermined whether some forms of primitive life might exist, or might have existed, somewhere in the Solar System. [[Extrasolar planets]] were observed for the first time. === Agriculture === [[File:Wheat yields in Least Developed Countries.svg|thumb|Wheat yields greatly increased from the [[Green Revolution]] in the world's [[least developed countries]].]] *[[Norman Borlaug]] fathered the [[Green Revolution]], the set of research [[technology transfer]] initiatives occurring between 1950 and the late 1960s that increased agricultural production in parts of the world, beginning most markedly in the late 1960s, and is often credited with saving over a billion people worldwide from starvation. === Biology === * [[Genetics]] was unanimously accepted and significantly developed. The [[structure of DNA]] was determined in 1953 by [[James D. Watson|James Watson]],<ref name="nobelmedicine1962">{{cite web|title=The Nobel Prize in Physiology or Medicine 1962|url=https://www.nobelprize.org/nobel_prizes/medicine/laureates/1962/|work=NobelPrize.org|publisher=Nobel Media AB|access-date=November 5, 2011}}</ref><ref name="Franklin"/> [[Francis Crick]],<ref name="nobelmedicine1962"/><ref name="Franklin"/> [[Rosalind Franklin]]<ref name="Franklin">{{cite web |title=James Watson, Francis Crick, Maurice Wilkins, and Rosalind Franklin |url=https://www.sciencehistory.org/historical-profile/james-watson-francis-crick-maurice-wilkins-and-rosalind-franklin |work=Science History Institute |access-date=20 March 2018 |date=June 2016 |archive-url=https://web.archive.org/web/20180321132408/https://www.sciencehistory.org/historical-profile/james-watson-francis-crick-maurice-wilkins-and-rosalind-franklin |archive-date=21 March 2018 |url-status=dead }}</ref> and [[Maurice Wilkins]],<ref name="nobelmedicine1962"/><ref name="Franklin"/> following by developing techniques which allow to read DNA sequences and culminating in starting the [[Human Genome Project]] (not finished in the 20th century) and [[Dolly (sheep)|cloning the first mammal]] in 1996. * The role of [[sexual reproduction]] in evolution was understood, and [[bacterial conjugation]] was discovered. * The convergence of various sciences for the formulation of the [[modern synthesis (20th century)|modern evolutionary synthesis]] (produced between 1936 and 1947), providing a widely accepted account of [[evolution]]. === Medicine === [[File:Faroe stamp 079 europe (fleming).jpg|thumb|right|A stamp commemorating [[Alexander Fleming]]. His discovery of [[penicillin]] changed the world of medicine by introducing the age of antibiotics.]] * [[Placebo]]-[[scientific control|controlled]], [[random sample|randomized]], [[blind experiment|blinded]] [[clinical trial]]s became a powerful tool for testing new medicines. * [[Antibiotics]] drastically reduced mortality from [[bacterial disease]]s. * 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 vaccine|influenza]], [[DPT vaccine|diphtheria, pertussis (whooping cough), tetanus]], [[MMR vaccine|measles]], [[mumps vaccine|mumps]], [[MMR vaccine|rubella (German measles)]], [[varicella vaccine|chickenpox]], [[hepatitis A vaccine|hepatitis A]], and [[hepatitis B vaccine|hepatitis B]]. * [[Epidemiology]] and [[vaccination]] led to the eradication of the [[smallpox]] virus in humans. * [[X-ray]]s became a powerful diagnostic tool for a 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 [[antipsychotic]]s for treating [[hallucination]]s and [[delusion]]s, and [[antidepressant]]s 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 [[cure]]d or placed in [[remission (medicine)|remission]]. * The development of [[blood type|blood typing]] and [[blood bank]]ing made [[blood transfusion]] safe and widely available. * The [[invention]] and development of [[immunosuppressive drug]]s and [[tissue typing]] made [[organ transplant|organ and tissue transplantation]] a clinical reality. * New methods for [[heart surgery]] were developed, including [[pacemaker]]s and [[artificial heart]]s. * [[Cocaine]] and heroin were widely illegalized after being found to be addictive and destructive. [[Psychoactive drug]]s such as [[LSD]] and [[MDMA]] were discovered and subsequently prohibited in many countries. [[Prohibition of drugs]] caused a growth in the black market drug industry, and [[War on drugs|expanded enforcement]] led to a larger prison population in some countries.<ref>{{Cite web|last=Engel|first=Pamela|date=April 23, 2014|title=Watch How Quickly The War On Drugs Changed America's Prison Population|url=https://www.businessinsider.com/how-the-war-on-drugs-changed-americas-prison-population-2014-4?op=1|website=Business Insider}}</ref> * [[Contraceptive]] drugs were developed, which reduced population growth rates in industrialized countries, as well as decreased the taboo of [[premarital sex]] throughout many western countries. * The development of medical [[insulin]] during the 1920s helped raise the life expectancy of [[diabetes|diabetics]] to three times of what it had been earlier. * Vaccines, hygiene and clean water improved health and decreased mortality rates, especially among infants and the young. ==== Notable diseases ==== * An [[influenza]] pandemic, [[1918 flu pandemic|Spanish Flu]], killed anywhere from 17 to 100 million people between 1918 and 1919. * A new [[virus|viral]] disease, called the [[Human Immunodeficiency Virus]], or HIV, arose in Africa and subsequently killed millions of people throughout the world. HIV leads to a syndrome called [[Acquired Immunodeficiency Syndrome]], or AIDS. Treatments for HIV remained inaccessible to many people living with AIDS and HIV in [[developing countries]], and a cure has yet to be discovered. * Because of increased [[Life expectancy|life spans]], the [[prevalence]] of cancer, [[Alzheimer's disease]], [[Parkinson's disease]], and other diseases of [[old age]] increased slightly. * Changes in food production, along with [[sedentary lifestyle]]s due to labor-saving devices and the increase in home entertainment, contributed to an "epidemic" of [[obesity]], at first in the rich countries, but by the end of the 20th century spreading to the developing world. === Energy and the environment === [[File:Oilfields California.jpg|thumb|[[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]].]] * [[Fossil fuels]] and [[nuclear power]] were the dominant forms of 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 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). * The increase in [[fossil fuel]] consumption also fueled a major scientific controversy over its effect on air pollution, [[global warming]], and global [[climate change]]. * [[Pesticide]]s, [[herbicide]]s and other [[toxicity|toxic]] [[chemical substance|chemicals]] accumulated in the environment, including in the bodies of humans and other animals. * [[Population growth]] and worldwide [[deforestation]] diminished the [[environmental quality|quality of the environment]]. * In the last third of the century, concern about humankind's impact on the Earth's [[environment (biophysical)|environment]] made environmentalism popular. In many countries, especially in Europe, the movement was channeled into politics through [[Green party|Green parties]]. Increasing awareness of [[global warming]] began in the 1980s, commencing decades of social and political debate. Summary: Please note that all contributions to Christianpedia may be edited, altered, or removed by other contributors. If you do not want your writing to be edited mercilessly, then do not submit it here. You are also promising us that you wrote this yourself, or copied it from a public domain or similar free resource (see Christianpedia:Copyrights for details). Do not submit copyrighted work without permission! Cancel Editing help (opens in new window) Discuss this page