Science (from the Latin word scientia, meaning "knowledge") is a systematic enterprise that builds and organizes knowledge in the form of testable explanations and predictions about the universe.
The earliest roots of science can be traced to Ancient Egypt and Mesopotamia in around 3500 to 3000 BCE. Their contributions to mathematics, astronomy, and medicine entered and shaped Greek natural philosophy of classical antiquity, whereby formal attempts were made to explain events of the physical world based on natural causes. After the fall of the Western Roman Empire, knowledge of Greek conceptions of the world deteriorated in Western Europe during the early centuries (400 to 1000 CE) of the Middle Ages but was preserved in the Muslim world during the Islamic Golden Age. The recovery and assimilation of Greek works and Islamic inquiries into Western Europe from the 10th to 13th century revived natural philosophy, which was later transformed by the Scientific Revolution that began in the 16th century as new ideas and discoveries departed from previous Greek conceptions and traditions. The scientific method soon played a greater role in knowledge creation and it was not until the 19th century that many of the institutional and professional features of science began to take shape.
Modern science is typically divided into three major branches that consist of the natural sciences (e.g., biology, chemistry, and physics), which study nature in the broadest sense; the social sciences (e.g., economics, psychology, and sociology), which study individuals and societies; and the formal sciences (e.g., logic, mathematics, and theoretical computer science), which study abstract concepts. There is disagreement, however, on whether the formal sciences actually constitute a science as they do not rely on empirical evidence. Disciplines that utilize existing scientific knowledge for practical purposes, such as engineering and medicine, are described as applied sciences.
Science is based on research, which is commonly conducted in academic and research institutions as well as in government agencies and companies. The practical impact of scientific research has led to the emergence of science policies that seek to influence the scientific enterprise by prioritizing the development of commercial products, armaments, health care, and environmental protection.
, also known as marine litter, is human-created waste
that has deliberately or accidentally become afloat in a lake
. A form of water pollution
, oceanic debris tends to accumulate at the centre of gyres
and on coastlines
. Some forms of marine debris, such as harmless driftwood
, occur naturally, and human activities have been adding similar material into the oceans for thousands of years. Only recently, however, with the advent of plastic
, has human influence become an issue as many types of plastics do not biodegrade
. Waterborne plastic is both unsightly and dangerous; posing a serious threat to fish
, marine reptiles
, and marine mammals
, as well as to boats and coastal habitations. Ocean dumping, accidental container spillages, and wind-blown landfill waste are all contributing to this growing problem.
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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