The Scientific Revolution saw the inception of the modern scientific method to guide the evaluation of knowledge. This change is considered to be so fundamental that older inquiries are known as pre-scientific. Still, many place ancient natural philosophy clearly within the scope of the history of science.

The history of mathematics, the history of technology, and the history of philosophy are covered in different articles. Mathematics is closely related to, but distinct from science (at least in the modern conception). Technology concerns the creative process of designing useful objects and systems, which differs from the search for empirical truth. Philosophy differs from science in that, while both the natural and the social sciences attempt to base their theories on established fact, philosophy also enquires about other areas of knowledge, notably ethics. In practice, each of these fields is heavily used by the others as an external tool.

In the West, from antiquity up to the time of the Scientific Revolution, inquiry into the workings of the universe was known as natural philosophy, and those engaged in it were known as natural philosophers. This included some fields of study which are no longer considered scientific). An account of the development of (natural) philosophy from ancient times until recent times can be found in Bertrand Russell's History of Philosophy. In many cases, systematic learning about the natural world was a direct outgrowth of religion, often as a project of a particular religious community.

One important feature of "pre-scientific" inquiry (whether in the West or elsewhere) was reluctance to engage in experiment. For example, Aristotle, one of the most prolific natural philosophers of antiquity, made countless observations of nature, especially the habits and attributes of plants and animals in the world around him. He focused on categorizing, and made many observations on the large-scale workings of the universe, which led to the development of a comprehensive theory of physics (see Physics (Aristotle)). Yet, until the period of the Scientific Revolution, these theories were never really tested experimentally. At the time, the utility of experiment was unproven. Some believed that setting up artificial conditions in an experiment could never produce results that would describe nature as it was in the world around them.

Map of Medieval Universities

With the loss of the Western Roman Empire, much of Europe lost contact with the knowledge of the past. Because of this regression in knowledge, the long period that followed is also known as the Dark Ages. While the Byzantine Empire still held learning centers such as Alexandria and Constantinople, Western Europes knowledge was concentrated in monasteries until the development of medieval universities in the 12th and 13th centuries. Initially these universities were organized to only teach theology, but people like Roger Bacon encouraged teaching of the sciences. Scientific teaching of the period was based upon copies of ancient texts that remained in Western Europe, and is known as the philosophic school of scholasticism. The rise of Christianity saw a strange paradox: classical Greek philosophy (along with Greek and Roman art, literature and religious iconography) was suppressed while at the same time it was safeguarded.

Islamic medical text

In the Middle East, Greek philosophy was able to find some short-lived support by the newly created Arab Caliphate (Empire). With the spread of Islam in the 7th and 8th centuries, a period of Islamic scholarship lasted until the 14th century. This scholarship was aided by several factors. The use of a single language, Arabic, allowed communication without need of a translator. Access to Greek and Roman texts from the Byzantine Empire along with Indian sources of learning provided Islamic scholars a knowledge base to build upon. In addition, there was the Hajj. This annual pilgrimage to Mecca facilitated scholarly collaboration by bringing together people and new ideas from all over the Islamic world.

In Islamic versions of early scientific method, ethics played an important role. During this period the concepts of citation and peer review were developed. Previous work in medicine, astronomy and mathematics led to the development of alchemy. In mathematics, the Islamic scholar Muhammad ibn Musa al-Khwarizmi gave his name to what is now called an algorithm; the word algebra is derived from al-jabr, the beginning of the title of one of his publications. Al-Batani (850-929) contributed to astronomy and mathematics and Al-Razi to chemistry. The fruits of these contributions can be seen in Damascus steel (wootz steel), and the Baghdad Battery. Arab alchemy inspired Roger Bacon, and later Isaac Newton, too. In astronomy, Al-Batani improved the measurements of Hipparchus, preserved in the translation of the Greek Hè Megalè Syntaxis (The great treatise) translated as Almagest. Al-Batani also improved the precision of the measurement of the precession of the earth's axis.

Vitruvian Man

The Renaissance was instigated by rediscovery of the works of ancient philosophers and an intellectual revitalization of Europe. This provided a solid foundation for all future scientific work. Contact with the Islamic world in Sicily and Spain allowed Europeans access to preserved copies of Greek and Roman works along with the works of Islamic philosophers. Translations and commentaries of Aristotle by the Islamic scholar Averroës were influential in much of Europe. The published works of Marco Polo along with the Crusades helped spark interest in geography. Most importantly, the development of the printing press in the 1450s allowed for new ideas to be rapidly copied to multiple people.

The willingness to question previously held truths and search for new answers resulted in a period of major scientific advancements, now known as the Scientific Revolution. The Scientific Revolution is held by most historians (e.g., Howard Margolis) to have begun in 1543, when there was brought to the Polish astronomer Nicolaus Copernicus the first printed copy of the book De Revolutionibus. The thesis of this book is that the Earth moves around the Sun. The period culminated with the publication of the Philosophiae Naturalis Principia Mathematica in 1687 by Isaac Newton.

Other significant scientific advances were made during this time by Galileo Galilei, Christiaan Huygens, Johannes Kepler, and Blaise Pascal. In philosophy, major contributions were made by Francis Bacon, Sir Thomas Browne, René Descartes, and Thomas Hobbes. The basics of scientific method were also developed: the new way of thinking emphasized experimentation and reason over traditional considerations.

Important developments took place during World War II, which led to the practical application of radar and the development and use of the atomic bomb. Though the process had begun with the invention of the cyclotron by Ernest O. Lawrence in the 1930s, physics in the postwar period entered into a phase of what historians have called "Big Science", requiring massive machines, budgets, and laboratories in order to test their theories and move into new frontiers. The primary patron of physics beame state governments, who recognized that the support of "basic" research could often lead to technologies useful to both military and industrial applications. Currently, general relativity and quantum mechanics are inconsistent with each other, and efforts are underway to unify the two.

  Diagram of the

  expanding universe

The Synthesis of urea by Friedrich Wöhler, opened a new research field in chemistry, and by the end of the 19th century, scientists were able to synthesize hundreds of organic compounds. The later part of the nineteenth century saw the exploitation of the petrochemicals of the earth, after the exhaustion of the oil supply from whaling in the previous centuries. Systematic production of refined materials provided a ready supply of products which not only provided energy, but also synthetic materials for clothing, medicine, and everyday disposable resources, by the twentieth century.

By the twentieth century, the integration of physics and chemistry was complete, with chemical properties explained as the result of the electronic structure of the atom; Linus Pauling's book on The Nature of the Chemical Bond used the principles of quantum mechanics to deduce bond angles in ever-more complicated molecules, culiminating in the physical modelling of the DNA molecule, in essence, the secret of life, in the words of Francis Crick. In the same year, the Miller-Urey experiment demonstrated that basic constituents of DNA, simple amino acids, could themselves be built up from simpler molecules in a simulation of primordial processes on Earth.

seafloor spreading

continental drift

illustrated on relief globe

The work on rocks Peri lithōn by Theophrastus, remained authoritative for millennia: its interpretation of fossils was not overturned until after the Scientific Revolution. By the 1700s Jean-Etienne Guettard and Nicolas Desmarest hiked central France and recorded their observations on geological maps; Guettard recorded the first observation of the volcanic origins of this part of France. James Hutton recorded his Theory of the Earth in the 1788 Transactions of the Royal Society of Edinburgh, later called uniformitarianism.

In 1811 Georges Cuvier and Alexandre Brongniart published their explanation of the antiquity of the Earth, inspired by Cuvier's discovery of fossil elephant bones in Paris. They formulated the principle of stratigraphic succession of the layers of the earth. They were independently anticipated by William Smith's stratigraphic studies on England and Scotland. By 1827 Charles Lyell's Principles of Geology reiterated Hutton's uniformitarianism, which influenced the thought of Charles Darwin.

The most significant advance in 20th century geology has been the development of the theory of plate tectonics in the 1960s. Plate tectonic theory arose out of two separate geological observations: seafloor spreading and continental drift. The theory revolutionized the Earth sciences.

exploration of the

solar system

Advances in astronomy and in optical systems in the 19th century resulted in the first observation of an asteroid (Ceres) in 1801, and the discovery of Neptune in 1846. In the 1840s, the first galaxies outside our solar system were observed by (William Parsons).

George Gamow, Ralph Alpher, and Robert Herman had calculated that there should be evidence for a Big Bang in the background temperature of the universe¹. In 1964, Arno Penzias and Robert Wilson² discovered a 3 kelvin background hiss in their Bell Labs radiotelescope, which was evidence for this hypothesis, and formed the basis for a number of results that helped determine the age of the universe.

Supernova SN1987A was observed by astronomers on Earth both visually, and in a triumph for neutrino astronomy, by the solar neutrino detectors at Kamiokande. But the solar neutrino flux was a fraction of its theoretically-expected value. This discrepancy forced a change in some values in the standard model for particle physics.

Semi-conservative

DNA replication.

Hungarian physician Ignác Fülöp Semmelweis in 1847 dramatically reduced the occurrence of puerperal fever by the simple experiment of requiring physicians to wash their hands before attending to women in childbirth. His discovery predated the germ theory of disease. However, his discoveries were not appreciated by his contemporaries and came into use only with discoveries of British surgeon Joseph Lister, who in 1865 proved the principles of antisepsis. His work is based on the very important discoveries made by French biologist Louis Pasteur. He was able to link some microorganisms with disease. This brought a revolution in medicine. He also devised one of the most important methods in preventive medicine, when in 1880 he produced the vaccine against rabies. Pasteur also invented the process of pasteurization to help prevent the spread of disease through milk and other foods.

Among the most prominent and far-reaching theories in all of science was the theory of evolution by natural selection put forth by the British naturalist Charles Darwin in his On the Origin of Species in 1859. Darwin's theory proposed that all differences in animals were formed by natural processes over long periods of time, and that even humans were simply evolved organisms. Implications of evolution on fields outside of pure science have led to both opposition and support from different parts of society, and profoundly influenced the popular understanding of "man's place in the universe".

In the early 20th century, the study of heredity became a major investigation after the rediscovery in 1900 of the laws of inheritance developed by the Austrian monk Gregor Mendel in 1866. Mendel's laws provided the beginnings of the study of genetics, which became a major field of research for both scientific and industrial research. By 1953 James Watson and Francis Crick clarified the basic structure of DNA, the genetic material for expressing life in all its forms³. In the late 20th century, the possibilities of genetic engineering became practical for the first time, and a massive international effort began in 1990 to map out an entire human genome (the Human Genome Project) has been touted as potentially having large medical benefits.

 Moon, Apollo 8, NASA

The famous Earthrise picture, taken in 1968 by the astronauts of Apollo 8, was important in creating awareness of the finiteness of Earth, and the limits of its natural resources. The interconnection and independence of each component ecosystem may imply that human beings should not overexploit Earth's resources, without regard for its main ecosystems (air, water, ground, plants and animals). This change of sensitivity to ecological issues has now been well established in Western civilization. Still, industrialized deforestation has occurred in the exploitation of the forests of Southeast Asia and the Amazon rainforest. It may be hypothesized that other vital and free goods (such as air) will, one day, be subject to price.