Science (from Latin scientia, meaning "knowledge") is a systematic enterprise that builds and organizes knowledge in the form of testable explanations and predictions about the universe. In an older and closely related meaning, "science" also refers to a body of knowledge itself, of the type that can be rationally explained and reliably applied. A practitioner of science is known as a scientist.

In classical antiquity, science as a type of knowledge was closely linked to philosophy. During the Islamic Golden Age, the foundation for the scientific method was laid, which emphasized experimental data and reproducibility of its results.During the early modern period in the West the words "science" and "philosophy of nature" were sometimes used interchangeably and not until the 17th century, natural philosophy (which is today called "natural science") was considered a separate branch of philosophy.

In modern usage, "science" most often refers to a way of pursuing knowledge, not only the knowledge itself. It is also often restricted to those branches of study that seek to explain the phenomena of the material universe. In the 17th and 18th centuries scientists increasingly sought to formulate knowledge in terms of laws of nature such as Newton's laws of motion. And over the course of the 19th century, the word "science" became increasingly associated with the scientific method itself, as a disciplined way to study the natural world, including physicschemistrygeology and biology. It is in the 19th century also that the term scientist was created by the naturalist-theologian William Whewell to distinguish those who sought knowledge on nature from those who sought other types of knowledge .

However, "science" has also continued to be used in a broad sense to denote reliable and teachable knowledge about a topic, as reflected in modern terms like library science or computer science. This is also reflected in the names of some areas of academic study such as "social science" or "political science".


The first complete Einstein ring, designated B1938+666, was discovered by collaboration between astronomers at the University of Manchester and NASA's Hubble Space Telescope in 1998.

Philosophical study of nature

Before the invention or discovery of the concept of "nature" (Ancient Greek phusis), by the Pre-Socratic philosophers, the same words tend to be used to describe the natural "way" in which a plant grows, and the "way" in which, for example, one tribe worships a particular god. For this reason it is claimed these men were the first philosophers in the strict sense, and also the first people to clearly distinguish "nature" and "convention". Science was therefore distinguished as the knowledge of nature, and the things which are true for every community, and the name of the specialized pursuit of such knowledge was philosophy — the realm of the first philosopher-physicists. They were mainly speculators or theorists, particularly interested in astronomy. In contrast, trying to use knowledge of nature to imitate nature (artifice or technology, Greek technē) was seen by classical scientists as a more appropriate interest for lower class artisans.

Nature (philosophy)

Nature is a concept with two major sets of inter-related meanings, referring on the one hand to the things which are natural, or subject to the normal working of "laws of nature", or on the other hand to the essential properties and causes of those things to be what they naturally are, or in other words the laws of nature themselves.

How to understand the meaning and significance of nature has been a consistent theme of discussion within the history of Western Civilization, in the philosophical fields ofmetaphysics and epistemology, as well as in theology and science. The study of natural things and the regular laws which seem to govern them, as opposed to discussion about what it means to be natural, is the area of natural science.

The word "nature" derives from Latin nātūra, a philosophical term derived from the verb for birth, which was used as a translation for the earlier Ancient Greek term phusiswhich was derived from the verb for natural growth, for example that of a plant. Already in classical times, philosophical use of these words combined two related meanings which have in common that they refer to the way in which things happen by themselves, "naturally", without "interference" from human deliberation, divine intervention, or anything outside of what is considered normal for the natural things being considered.

Understandings of nature depend on the subject and age of the work where they appear. For example Aristotle's explanation of natural properties differs from what is meant by natural properties in modern philosophical and scientific works, which can also differ from other scientific and conventional usage.

Plato (left) and Aristotle (right), a detail of The School of Athens, a fresco by Raphael.


Classical nature and Aristotelian metaphysics

The Physics (from physis, Greek for "nature") is Aristotle's principal work on nature. In Physics II.1, Aristotle defines a nature as "a source or cause of being moved and of being at rest in that to which it belongs primarily". In other words, a nature is the principle within a natural raw material that is the source of tendencies to change or rest in a particular way unless stopped. For example a rock would fall unless stopped. Natural things stand in contrast to artifacts, which are formed by human artifice, not because of an innate tendency. (The raw materials of a bed have no tendency to become a bed.) In terms of Aristotle's theory of four causes, the word natural is applied both to the innate potential of matter cause and the forms which the matter tends to become naturally.

According to Leo Strauss, the beginning of Western philosophy involved the "discovery or invention of nature" and the "pre-philosophical equivalent of nature" was supplied by "such notions as 'custom' or 'ways'". In ancient Greek philosophy on the other hand, Nature or natures are ways that are "really universal" "in all times and places". What makes nature different is that it presupposes not only that not all customs and ways are equal, but also that one can "find one's bearings in the cosmos" "on the basis of inquiry" (not for example on the basis of traditions or religion). To put this "discovery or invention" into the traditional terminology, what is "by nature" is contrasted to what is "by convention". The concept of nature taken this far remains a strong tradition in modern western thinking. Science, according to Strauss' commentary of Western history is the contemplation of nature, while technology was or is an attempt to imitate it.

Going further, the philosophical concept of nature or natures as a special type of causation - for example that the way particular humans are is partly caused by something called "human nature" is an essential step towards Aristotle's teaching concerning causation, which became standard in all Western philosophy until the arrival of modern science.


Einstein cross.jpg
The Einstein Cross or Q2237+030 or QSO 2237+0305 is a gravitationally lensed quasar that sits directly behind ZW 2237+030, Huchra's Lens. Four images of the same distant quasar appear around a foreground galaxy due to strong gravitational lensing.


Should science aim to determine ultimate truth, or are there questions that science cannot answerScientific realists claim that science aims at truth and that one ought to regard scientific theories as true, approximately true, or likely true. Conversely, scientific anti-realists argue that science does not aim (or at least does not succeed) at truth, especially truth about unobservables like electrons or other universes. Instrumentalists argue that scientific theories should only be evaluated on whether they are useful. In their view, whether theories are true or not is beside the point, because the purpose of science is to make predictions and enable effective technology.

Realists often point to the success of recent scientific theories as evidence for the truth (or near truth) of current theories. Antirealists point to either the many false theories in the history of science, epistemic morals, the success of false modeling assumptions, or widely termed postmodern criticisms of objectivity as evidence against scientific realism. Antirealists attempt to explain the success of scientific theories without reference to truth. Some antirealists claim that scientific theories aim at being accurate only about observable objects and argue that their success is primarily judged by that criterion.

Values and science

If it is unclear what counts as science, how the process of confirming theories works, and what the purpose of science is, there is considerable scope for values and other social influences to shape science. Indeed values can play a role ranging from determining which research gets funded to influencing which theories achieve scientific consensus. Feminist philosophers of science, sociologists of science, and others explore how social values affect science.






The history of science is the study of the historical development of science and scientific knowledge, including both thenatural sciences and social sciences. (The history of the arts and humanities is termed as the history of scholarship.) From the 18th century through late 20th century, the history of science, especially of the physical and biological sciences, was often presented in a progressive narrative in which true theories replaced false beliefs. More recent historical interpretations, such as those of Thomas Kuhn, tend to portray the history of science in more nuanced terms, such as that of competing paradigms or conceptual systems in a wider matrix that includes intellectual, cultural, economic and political themes outside of science.

Science is a body of empiricaltheoretical, and practical knowledge about the natural world, produced by scientists who emphasize the observation, explanation, and prediction of real world phenomenaHistoriography of science, in contrast, often draws on the historical methods of both intellectual history and social history. However, the English word scientist is relatively recent—first coined by William Whewell in the 19th century. Previously, people investigating nature called themselves natural philosophers.

While empirical investigations of the natural world have been described since classical antiquity (for example, by Thales,Aristotle, and others), and scientific methods have been employed since the Middle Ages (for example, by Ibn al-Haytham, and Roger Bacon), the dawn of modern science is often traced back to the early modern period and in particular to thescientific revolution that took place in 16th- and 17th-century Europe. Scientific methods are considered to be so fundamental to modern science that some consider earlier inquiries into nature to be pre-scientific. Traditionally, historians of science have defined science sufficiently broadly to include those inquiries.


In prehistoric times, advice and knowledge was passed from generation to generation in an oral tradition. For example, the domestication of maize for agriculture has been dated to about 9,000 years ago in southern Mexico, before the development of writing systems. Similarly, archaeological evidence indicates the development of astronomical knowledge in preliterate societies.

The development of writing enabled knowledge to be stored and communicated across generations with much greater fidelity. Combined with the development of agriculture, which allowed for a surplus of food, it became possible for early civilizations to develop, because more time could be devoted to tasks other than survival .

Many ancient civilizations collected astronomical information in a systematic manner through simple observation. Though they had no knowledge of the real physical structure of the planets and stars, many theoretical explanations were proposed. Basic facts about human physiology were known in some places, and alchemy was practiced in several civilizations. Considerable observation of macrobiotic flora and fauna was also performed.

Ancient Near East

From their beginnings in Sumer (now Iraq) around 3500 BC, the Mesopotamian people began to attempt to record someobservations of the world with numerical data. But their observations and measurements were seemingly taken for purposes other than for scientific laws. A concrete instance of Pythagoras' law was recorded, as early as the 18th century BC: the Mesopotamian cuneiform tablet Plimpton 322 records a number of Pythagorean triplets (3,4,5) (5,12,13). ..., dated 1900 BC, possibly millennia before Pythagoras,  but an abstract formulation of the Pythagorean theorem was not.

In Babylonian astronomy, records of the motions of the starsplanets, and the moon are left on thousands of clay tablets created by scribes. Even today, astronomical periods identified by Mesopotamian scientists are still widely used in Western calendars such as the solar year and the lunar month. Using these data they developed arithmetical methods to compute the changing length of daylight in the course of the year and to predict the appearances and disappearances of the Moon and planets and eclipses of the Sun and Moon. Only a few astronomers' names are known, such as that of Kidinnu, a Chaldean astronomer and mathematician. Kiddinu's value for the solar year is in use for today's calendars. Babylonian astronomy was "the first and highly successful attempt at giving a refined mathematical description of astronomical phenomena." According to the historian A. Aaboe, "all subsequent varieties of scientific astronomy, in the Hellenistic world, in India, in Islam, and in the West—if not indeed all subsequent endeavour in the exact sciences—depend upon Babylonian astronomy in decisive and fundamental ways .


Biblical cosmology provides sporadic glimpses that may be stitched together to form a Biblical impression of the physical universe. There have been comparisons between the Bible, with passages such as from the Genesis creation narrative, and the astronomy of classical antiquity more generally.

The worldview of the Tanakh (or Old Testament) appears to be that of a flat earth (e.g. Isaiah 11:12 , Isaiah 44:24 ) in ageocentric universe (e.g. Joshua 10:12-13Ps. 93:11 Chron. 16:30), a view in line with Mesopotamian astronomy of the period.[2] However, Christians claim that the term chuwg 'erets in Isaiah 40:22 translates as 'circle of the Earth', thus referring to a "round earth". Critics, on the other hand, assert that it meant a "flat earth", claiming that if Isaiah wanted to refer to a spherical earth, he would have used the term kadur (sphere) in Hebrew . The spherical shape of the earth was established in the west only in Hellenistic astronomy, in the 3rd century BCE. The first suggestions of heliocentrism in Europe also date to the Hellenistic period but remained speculative until the 16th century CE. Recent measurements from satellitesshow that the Earth is, in fact, an oblate spheroid flattened at the poles.






Plimpton 322


The main content of Plimpton 322

Plimpton 322 is a Babylonian clay tablet, notable as containing an example of Babylonian mathematics. It has number 322 in the G.A. Plimpton Collection at Columbia University. This tablet, believed to have been written about1800 BC, has a table of four columns and 15 rows of numbers in the cuneiform script of the period.
This table lists what are now called Pythagorean triples, i.e., integers abc satisfying \scriptstyle a^2+b^2=c^2. From a modern perspective, a method for constructing such triples is a significant early achievement, known before only among theGreeks. At the same time, one should recall the tablet's author was a scribe, rather than a professional mathematician; it has been suggested that one of his goals may have been to produce examples for school problems.





















































The Periodic Table

Author: Dr. Doug Stewart

The periodic table we use today is based on the one devised and published by Dmitri Mendeleev in 1869.

Mendeleev found he could arrange the 65 elements then known in a grid or table so that each element had:

1. A higher atomic weight than the one on its left. For example, magnesium (atomic weight 24.3) is placed to the right of sodium (atomic weight 23.0):



2. Similar chemical properties to other elements in the same column - in other words similar chemical reactions. Magnesium, for example, is placed in the alkali earths' column:


Mendeleev realized that the table in front of him lay at the very heart of chemistry. And more than that, Mendeleev saw that his table was incomplete - there were spaces where elements should be, but no-one had discovered them.

Just as Adams and Le Verrier could be said to have discovered the planet Neptune on paper, Mendeleev could be said to have discovered germanium on paper. He called this new element eka-silicon, after observing a gap in the periodic table between silicon and tin:


Similarly, Mendeleev discovered gallium (eka-aluminum) and scandium (eka-boron) on paper, because he predicted their existence and their properties before their actual discoveries.

Although Mendeleev had made a crucial breakthrough, he made little further progress. With the benefit of hindsight, we know that Mendeleev's periodic table was underpinned by false reasoning. Mendeleev believed, incorrectly, that chemical properties were determined by atomic weight. Of course, this was perfectly reasonable when we consider scientific knowledge in 1869.

In 1869 the electron itself had not been discovered - that didn't happen for another 27 years.

In fact, it took all of 44 years for the correct explanation of the regular patterns in Mendeleev's periodic table to be found..