is the methodical study of nature including testable explanations
. From classical antiquity
through the 19th century, science as a type of knowledge was more closely linked to philosophy
than it is now and, in fact, in the Western world
, the term "natural philosophy
" encompassed fields of study that are today associated with science, such as astronomy
, medicine, and physics
. However, during the Islamic Golden Age
foundations for the scientific method
were laid by Ibn al-Haytham
in his Book of Optics
. While the classification of the material world by the ancient Indians
into air, earth, fire and water
was more philosophical, medieval Middle Easterns
used practical, experimental observation
to classify materials.
Today, the ever-evolving term "science" refers to the pursuit of knowledge, not the knowledge itself. It is often synonymous with "natural and physical science" and often restricted to those branches of study relating to the phenomena of the material universe and their laws. Although the term implies exclusion of pure mathematics, many university faculties include Mathematics Departments within their Faculty of Science. The dominant sense in ordinary use has a narrower use for the term "science." It developed as a part of science becoming a distinct enterprise of defining the "laws of nature"; early examples include Kepler's laws, Galileo's laws, and Newton's laws of motion. In this period it became more common to refer to natural philosophy as "natural science." Over the course of the 19th century, the word "science" became increasingly associated with the disciplined study of the natural world, including physics, chemistry, geology and biology. This sometimes left the study of human thought and society in a linguistic limbo, which was resolved by classifying these areas of academic study as social science. For example, psychology evolved from philosophy, and has grown into an area of study.
Currently, there are both "hard" (e.g. biological psychology) and "soft" science (e.g. social psychology) fields within the discipline. As a result, and as is consistent with the unfolding of the study of knowledge and development of methods to establish facts, each area of psychology employs a scientific method. Reflecting the evolution of the development of knowledge and established facts and the use of the scientific method, Psychology Departments in universities are found within: Faculty of Arts and Science, Faculty of Arts, and a Faculty of Science. Similarly, several other major areas of disciplined study and knowledge exist today under the general rubric of "science", such as formal science and applied science.
is a change in the genetic
makeup of a population within a species
. Since the emergence of modern genetics
in the 1940s
, evolution has been defined more specifically as a change in the frequency of alleles
from one generation to the next. The word "evolution" is often used as a shorthand for the modern theory
of evolution of species
based upon Charles Darwin
's theory of natural selection
, which states that all modern species are the products of an extensive process that began over three billion years ago with simple single-celled organisms
, and Gregor Mendel
's theory of genetics
. As the theory of evolution by natural selection and genetics has become universally accepted in the scientific community, it has replaced other explanations including creationism
. Skeptics, often creationists, sometimes deride evolution as "just a theory" in an attempt to characterize it as an arbitrary choice and degrade its claims to truth. Such criticism overlooks the scientifically
-accepted use of the word "theory" to mean a falsifiable
and well-supported hypothesis
Direct current-generated plasma (violet) enhances the growth of carbon nanotubes in this laboratory-scale PECVD apparatus. Plasma-enhanced chemical vapor deposition processes utilize plasma to enhance chemical reaction rates. PECVD processing allows deposition at lower temperatures, which is often critical in the manufacture of semiconductors. The red color in the picture is black-body radiation.
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