Science & Philosophy: Philosophy of Mind - Early Ideas to Planck length
Philosophy of Mind - Ancient and Medieval - Ancient Greek And Roman Views, Medieval Views, Bibliography
The mind is a modern notion. But like many modern notions, it did not emerge from nowhere. What contemporary philosophers mean when they talk about the mind is part of a long tradition, stretching back through the Middle Ages to Greek and Roman antiquity. The mind in its modern sense is best understood in opposition to the body, the extended, flesh-and-blood entity that it seems to inhabit and mov…
Moral - Africa Philosophy - Morality Based On Religion In African Thought, Morality As Custom, Bibliography
Morality consists of two parts: first, morality in the strict sense; and second, morality as custom or mores. The defining principle of the first is the golden rule, that of the second, local utility, idiosyncrasy, or even accident. The first is known to be universal to all human cultures. This has to be so of a necessity, in view of what the rule entails. The golden rule, to follow Harry Gensler,…
Philosophy - Relations to other Intellectual Realms - After Plato, Medieval And Renaissance, Early Modern, Modern Times, Bibliography
For Plato, the first characteristic of philosophical wisdom is that it meet the needs of rational inquiry. As he suggests at Apology 22, this criterion precludes all types of quotidian knowledge and other homespun verities in favor of genuine philosophical insight. Neither the statesman, the artisan, nor the poet can explain why he is doing what is he doing, for none of them has formulated a clear…
Philosophy of Religion - Changing Conceptions, Modern Conceptions, Bibliography
A well-established discipline in early-twenty-first-century Western philosophy, the subject known as "the philosophy of religion" has not always been easily demarcated with respect to its nature and scope. The reason for this is historical. The long engagement of philosophy with the claims of religion has manifested itself from antiquity to the early twenty-first century in a wide va…
Philosophy and Religion in Western Thought - The Early Christian And Medieval Periods, The Early Modern Period, The Eighteenth And Nineteenth Centuries
In the works of Aristotle, criticisms of popular misconceptions of divinity and genuine moments of piety are combined. More important for later thinking about theology, however, are Aristotle's arguments for the existence of a divine prime mover of the universe and his account of that entity. At the end of Physics (book 8) and in Metaphysics (book 12), he argues that the impossibility of an…
Phlox
Phloxes (Phlox spp.) are a group of about 50 species of flowering plants in the family Polemoniaceae, which contains about 300 species in total. Phloxes are herbaceous plants with bright, showy flowers. Each flower has five red, pink, or white petals that are fused at their bases to form a tube, but remain separate at the top of the structure. These flowers are arranged in very attractive groups, …
Phobias
A phobia is a group of symptoms brought on by an object or situation that causes a person to feel irrational fear. For example, a person terrified by a snake poised to strike only a few feet away on a hiking trail experiences normal fear, while a person terrified by a snake in a glass cage would be said to be having a phobic reaction. A person suffering from a phobia may dwell on the object of his…
Phonograph
The first practical device for recording and reproducing sound was developed by Thomas A. Edison in 1877. He called his device a phonograph, meaning sound writer, because of the crude, mechanically cut impressions, or "writing," it made on the surface of the recording cylinder. The sound reproduction was equally crude. Since the time of Edison's phonograph, the quest for more …
Phoronids
Phoronids are a small group of tube-dwelling marine worms that comprise the phylum Phoronidae. Some 15 species have so far been described. All phoronids are exclusively marine-dwelling and live in shallow waters up to a depth of about 195 ft (60 m) in both tropical and temperate oceans. They are thought to be related to moss animals (phylum Bryozoa) and lamp shells (phylum Brachiopoda). They may o…
Phosphoric Acid
Phosphoric acid is a weak acid, with only a small percentage of the molecules in solution ionizing. Phosphoric acid is manufactured by the reaction of sulfuric acid upon phosphate rocks (commonly found in Florida), most notably calcium phosphate, as shown below: The other product of the reaction, calcium sulfate dihydrate is gypsum and is used in drywall in the construction industry. Alternat…
Phosphorus
Phosphorus is a chemical element with the atomic number 15 and atomic weight 30.9738. Phosphorus forms the basis of a large number of compounds, by far the most environmentally important of which are phosphates. All plants and animals need phosphates for growth and function, and in many natural waters the production of algae and higher plants is limited by the low natural levels of phosphorus. As …
Phosphorus Cycle - Biogeochemical Cycles, Phosphorus Functions And Recycling, Phosphorus As A Limiting Nutrient In Ecosystems
We live in a world that is constantly recycling materials. All life is composed of the very same matter that exists in the non-living, or abiotic, world. The elements that are found in living things, like carbon, hydrogen, and calcium are also found in abioic compounds of the environment, like soil or rock. Because the quantities of usable sources of materials and elements that compose the living …
Phosphorus Removal
Phosphorus (usually in the form of phosphate) is a normal part of the environment. It occurs in the form of phosphate containing rocks and as the excretory and decay products of plants and animals. Human contributions to the phosphorus cycle result primarily from the use of phosphorus-containing detergents and fertilizers. The increased load of phosphorus in the environment as a result of human ac…
Photic Zone - Other Layers In Oceans And Lakes, The Importance Of Nutrients And Light In Photic Zone, Research In The Photic Zone
The photic zone, also called the euphotic or limnetic zone, is the volume of water where the rate of photosynthesis is greater than the rate of respiration by phytoplankton. Phytoplankton are microscopic plants living suspended in the water column that have little or no means of motility. They are primary producers that use solar energy as a food source. The compensation point, where photosynthesi…
Photochemistry - The Basic Laws Of Photochemistry, Photochemistry Induced By Visible And Ultraviolet Light, Reaction Pathways, Dissociation - Ionization, Isomerization
Photochemistry is the study of light-induced chemical reactions and physical processes. A photochemical event involves the absorption of light to create an excited species that may subsequently undergo a number of different reactions. These include unimolecular reactions such as dissociation, ionization, and isomerization; bimolecular reactions, which involve a reaction with a second molecule or a…
Photoelectric Cell
During the latter half of the nineteenth century many scientists and engineers were simultaneously observing a strange phenomenon: electrical devices constructed from certain metals seemed to conduct electricity more efficiently in the daytime than at night. This phenomenon, called the photoelectric effect, had been noted years earlier by the French physicist A. E. Becquerel (1820-1891), who had i…
Electronic Photography - The Digital Still Camera, Applications, Video Cameras, Other Methods For Electronic Photography
Like all other forms of information, photographs and images have entered the electronic age. In 1981, the Sony Corporation unveiled its filmless, electronic camera (termed a still video camera) the Mavica. Mavica is an acronym for Magnetic Video Camera; it uses a still video system to record 50 analog images on a diskette. Although they are recorded on a diskette, they are not digital images. The …
Photon
The photon is the basic unit, particle, or carrier of light. The visible light that we see, the x rays that dentists use, and the radio waves that carry music to our radios are all forms of electromagnetic radiation. Other forms include the microwaves which we use to cook food and gamma rays which are produced when radioactive elements disintegrate. Although they seem quite different, all types o…
Photosynthesis - History Of Research, Location Of Light Reactions, Cam Photosynthesis, Photorespiration, Cyanobacteria, Anaerobic Photosynthetic Bacteria - Light reactions, Dark reactions, Photosynthesis in lower organisms, Chloroxybacteria
The overall equation in photosynthetic bacteria is similar, although not identical. In the light reactions of photosynthesis, light energy excites photosynthetic pigments to higher energy levels and this energy is used to make two high energy compounds, ATP (adenosine triphosphate) and NADPH (nicotinamide adenine dinucleotide phosphate). ATP and NADPH do not appear in the overall equation for…
Photovoltaic Cell - How They Work, Applications, Solar-electric Homes, Materials, Amorphous Silicon, Crystalline Silicon
A photovoltaic cell, often called a solar cell, converts the energy in light directly into electrical potential energy using a physical process called the photovoltaic effect. Photovoltaic cells are used to produce electricity in situations where they are more economical than other power generation methods. Occasionally, they are used as photodetectors. The photovoltaic effect has been known since…
Phrenology - Origins And Development, Decline, Bibliography
Phrenology, a science popular from the early to the mid-nineteenth century, was dedicated to the discernment of one's character or traits of personality from reading—that is, feeling the shape and size of—the bumps on one's skull. As formulated by the German physician and anatomist Franz Josef Gall (1758–1828) and as popularized by his student and follower Johann…
Phylogeny
Phylogeny is the inferred evolutionary history of a group of organisms. Paleontologists are interested in understanding life through time—not just at one time in the past or present, but over long periods of past time. Before they can attempt to reconstruct the forms, functions, and lives of once-living organisms, paleontologists have to place these organisms in context. The relationships o…
Physical Therapy - The modalities of physical therapy, Physical therapy and the aging adult
Physical therapy is a medical specialty that provides treatment using various devices or the hands to strengthen muscles and supply flexibility to a part of the body that is subnormal. The need for physical therapy can be the result of a genetic condition, disease, surgery, or a trauma such as a burn or automobile accident. The goal of physical therapy is not necessarily to restore normality but t…
Physics - Middle Ages, Sixteenth And Seventeenth Centuries, Eighteenth Century, Nineteenth Century, Causes Of Motion: Medieval Understandings
It should be understood that a full understanding of the history of physics would include consideration of its institutional, social, and cultural contexts. Physics became a scientific discipline during the nineteenth century, gaining a clear professional and cognitive identity as well as patronage from a number of institutions (especially those pertaining to education and the state). Before the n…
Physics - Classical And Modern Physics, Divisions Of Physics, Interrelationship Of Physics To Other Sciences, Physics And Philosophy
Physics is the science that deals with matter and energy and with the interaction between them. Physics, from which all other sciences derive their foundation, were the first attempts to provide rational explanations for the structure and workings of the Universe. Even in the earliest civilizations, physics allowed a mechanism to understand and quantify nature. An axiom among physicists—sin…
Physiology
Physiology is the study of how various biological components work independently and together to enable organisms, from animals to microbes, to function. This scientific discipline covers a wide variety of functions from the cellular and subcellular level to the interaction of organ systems that keep more complex biological machines, like humans, running. Physiological studies are aimed at answerin…
Comparative Physiology
While anatomy is the study of the structures of an organism, physiology is the science dealing with the study of the function of an organism's component structures. However, it often is not enough to know what an organ, tissue, or other structure does. Physiologists want to know how something functions. For example, physiological questions might ask: What is the function of human lung tissu…
Phytoplankton
Phytoplankton are microscopic, photosynthetic organisms that float in the water of the oceans and bodies of freshwater (the word phytoplankton is derived from the Greek for "drifting plants"). The most abundant organisms occurring within the phytoplankton are algae and blue-green bacteria, but this group also includes certain kinds of protists (especially protozoans) that contain sym…
Pi
Pi is one of the most fundamental constants in all of mathematics. It is normally first encountered in geometry where it is defined as the ratio of the circumference of a circle to the diameter: π = C/d where C is the circumference and d is the diameter. This fact was known to the ancient Egyptians who used for π the number 22/7 which is accurate enough for many applications. A clo…
Pietism - History, Significance Of Pietism, Bibliography
Like the Enlightenment, Pietism has produced an extremely diverse body of historical scholarship, with opinions ranging from a denial of its existence to precise nationally, geographically, or chronologically defined variants, as well as views that see Pietism essentially as identical with the history of modern Protestantism. Such divergent opinion has led to the introduction of categories such as…
Pigeons and Doves - Biology Of Pigeons And Doves, Pigeons Of North America, The Domestic Pigeon, The Passenger Pigeon
Pigeons and doves include about 300 species of birds in the family Columbidae. Most species are found in forests of various types, with fewer species occurring in more open habitats. By far the greatest richness of species of pigeons and doves occurs in moist tropical and sub-tropical forests. Many tropical oceanic islands have endemic species of pigeons and doves that evolved in isolation. Many o…
Pigs - Species Of Pigs, The Domestic Pig
Pigs, hogs, or swine consist of about eight species of mammals in the family Suidae, which is part of the order Artiodactyla, the cloven-hoofed ungulates. Pigs are closely related to the peccaries (family Tayassuidae) and hippopotamuses (family Hippopotamidae). The natural distribution of pigs includes Africa, Europe, and Asia, but one species, the domestic pig (Sus scrofa), is now found almost wo…
Pike
Pike are large carnivorous species of bony fish in the genus Esox in the family Esocidae. Pike occur in static and slowly flowing fresh-water habitats, throughout most of Europe, northern Asia, and North America. Pike have a relatively long, streamlined, fusiform body, adapted to swimming in rapid bursts to catch their prey of smaller fish (including other pike), amphibians, crayfish, small mammal…
Piltdown Hoax
On December 18, 1912, Charles Dawson (1865–1916) announced to the Geological Society in London that he had discovered skull fragments and a partial jaw in a gravel formation in Piltdown Common, Fletching, near Lewes, Sussex, England. The skull fragments were accompanied by bones of relatively recent hippopotamus, deer, beaver, and horse, as well as ancient bones of extinct mastodon and rhin…
Pinecone Fish
A pinecone fish has a plump, deep body, measuring about 5 in (12.7 cm) long. The body is covered by heavy, platelike scales that overlap, giving the fish the appearance of a pinecone-hence its name. Under each pinecone fish's lower jaw, there are two phosphorescent organs, giving the impression that the fish itself produces light. The light is actually produced by luminous bacteria that hav…
Pipefish
Pipefish (family Syngnathidae) are slim, elongate fish with large heads and extended, tubular mouths. The extended snout frequently measures more than half of the total head length. The body is enclosed in a tough, segmented skin and the fins, with the exception of the A pipefish (Sygnathus sp.) swimming through the water. Photograph by Herve Chaumeton. Photo Researchers, Inc. Reproduced by p…
Placebo
In medicine, especially in clinical trials conducted for medical research, a placebo is a substance used as a control in a double-blind study. Half of a group of test subjects are given a medicinal substance being investigated, while the other half is administered an inert material, like a sugar pill, made to look indistinguishable from the medicine. In the optimal double-blind test, neither the r…
Planck's Constant
At the beginning of the twentieth century, German physicist, Maxwell Planck, proposed that atoms absorb or emit electromagnetic radiation only in certain units or bundles of energy termed quanta. The concept that energy existed only in discrete and defined units seemed counter-intuitive, that is, outside the human experience with nature. Accepting his experimental results regarding the radiation e…