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 provide explanations of events in 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; along with the changing of "natural philosophy" to "natural science."
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 use 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.
A quantum computer
is any device for computation
that makes direct use of distinctively quantum mechanical
phenomena, such as superposition
, to perform operations on data. In a classical (or conventional) computer, the amount of data
is measured by bits
; in a quantum computer, it is measured by qubits
. The basic principle of quantum computation is that the quantum properties of particles can be used to represent and structure data, and that devised quantum mechanisms can be used to perform operations with this data. For a generally accessible overview of quantum computing, see Quantum Computing with Molecules
, an article in Scientific American
by Neil Gershenfeld
and Isaac L. Chuang.
Experiments have already been carried out in which quantum computational operations were executed on a very small number of qubits. Research in practical areas continues at a frantic pace; see Quantum Information Science and Technology Roadmap for a sense of where the research is heading. Many national government and military funding agencies support quantum computing research, to develop quantum computers for both civilian and national security purposes, such as cryptanalysis.
Deep Impact is a NASA space probe designed to study the composition of the interior of the comet Tempel 1. At 5:52 UTC on July 4, 2005, one section of the Deep Impact probe successfully impacted the comet's nucleus, excavating debris from the interior of the nucleus. Photographs of the impact showed the comet to be more dusty and less icy than expected. The impact generated a large, bright dust cloud that obscured the hoped-for view of the impact crater.
Richard Phillips Feynman
(May 11, 1918 – February 15, 1988) was one of the most influential American physicists of the 20th century, expanding greatly upon the theory of quantum electrodynamics
. As well as being an inspiring lecturer and amateur musician, also later he became a member of the panel which investigated the Space Shuttle Challenger disaster
. For his work on quantum electrodynamics, Feynman was one of the recipients of the Nobel Prize in Physics
in 1965, along with Julian Schwinger
and Shin-Ichiro Tomonaga
Feynman was a keen and influential popularizer of physics in both his books and lectures. He is famous for his many adventures, detailed in the books Surely You're Joking, Mr. Feynman!, What Do You Care What Other People Think? and Tuva or Bust!. Posthumously, Feynman is often credited with helping catalyze the field of nanotechnology through his December 1959 talk called There's Plenty of Room at the Bottom. Richard Feynman was, in many respects, an eccentric and a free spirit.
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