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Scientists maintain that scientific investigation must adhere to the scientific method, a process for properly developing and evaluating natural explanations for observable phenomena based on empirical study and independent verification. Science therefore, avoids supernatural explanations until all other natural possibilities have been considered, and rejects arguments from authority. Fields of science are commonly classified along two major lines: Natural sciences, which study natural phenomena; and Social sciences, which study human behavior and societies. Whether mathematics is a science is a matter of perspective. Fields of science can be further distinguished as pure science or applied science. Pure science is principally involved with the discovery of new truths with less (or no) regard to their applications. Applied science is principally involved with the application of existing knowledge in new ways.
A space elevator is a hypothetical structure designed to transport material from a planet's surface into space. Many different types of space elevator structures have been proposed. They all share the goal of replacing rocket propulsion with the traversal of a fixed structure via a mechanism not unlike an elevator, hence its name, in order to move material into or beyond orbit. Space elevators have also sometimes been referred to as space bridges, beanstalks, space ladders or space lifts. The most common proposal is a tether (usually a cable or ribbon) that spans from the surface to a point beyond geostationary orbit. As the planet rotates, the inertia at the end of the tether counteracts gravity and keeps the tether taut. Vehicles can then climb the tether and escape the planet's gravity without the use of rockets. Such a structure could eventually permit delivery of great quantities of cargo and people to orbit, and at costs only a fraction of those associated with current means.
An 18th Century Persian astrolabe used for determining the time at both day and night. The points of the curved spikes on the front rete plate, mark the positions of the brightest stars. The name of each star being labeled at the base of each spike. The back plate, or mater is engraved with projected coordinate lines. From the Whipple M
Santiago Ramón y Cajal (May 1, 1852 – October 17, 1934) was a famous Spanish histologist, physician, and Nobel laureate. He is considered to be one of the founders of modern neuroscience. His most famous studies were on the fine structure of the central nervous system. Cajal used a histological staining technique developed by his contemporary [[]] tissue continuous reticulum (or web) of in the circulatory system. Using Golgi's method, Ramón y Cajal reached a very different conclusion. He postulated that the nervous system is made up of billions of separate neurons and that these cells are polarized. Rather than forming a continuous web, Cajal suggested that neurons communicate with each other via specialized junctions called "synapses". This hypothesis became the basis of the neuron doctrine, which states that the individual unit of the nervous system is a single neuron. Electron microscopy later showed that a plasma membrane completely enclosed each neuron, supporting Cajal's theory, and weakening Golgi's reticular theory.
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