"There is nothing which so generally strikes the imagination, and engages the affections of mankind, as the right of property; or that sole and despotic dominion which one man claims and exercises over the external things of the world, in total exclusion of the right of any other individual in the universe" (p. 2). So wrote Sir William Blackstone (1723–1780), the great English…
The root of the English word prophecy is derived from the Greek prophēteia, Latin prophetia. The root of prophēteia is derived from prophēmi, which means to speak before or for someone or something. A cognate Greek word is prophētazō, which indicates the reception of the gift of interpreting the will of the gods—that is, the gift of prophecy. The gift of prophe…
Propane is a gas produced primarily from various refinery processes. It is often mixed with butane, a four carbon atomalkane, and sold as bottled gas or liquefied petroleum gas, LPG. The bottled gas is used as an inexpensive fuel for cooking and heating homes not located near natural gas lines. Since liquefied petroleum gas burns very cleanly, it is being used as an alternate fuel for cars, trucks…
Prosimians are the most primitive of the living primates, which also include the monkeys and apes. The name prosimian means pre-monkey. The living prosimians are placed in the suborder Prosimii, which includes four families of lemurs, (the Lemuridae, the Cheirogaleidae, the Indriidae, and the Daubentoniidae), the bush babies, lorises and pottos (family Lorisidae), and the tarsiers (family Tarsiida…
Prosthetics is a branch of surgery that is involved in devising and fabricating a prosthesis for a missing or infirm body part. A prosthesis is an artificial part used to restore some amount of normal body function. The classic example of a prosthesis is a false leg or arm to replace one that has been amputated. A diseased heart valve can be removed and replaced by an artificial one. Artificial bo…
Proteas are evergreen trees and shrubs belonging to the dicotyledonous plant family Proteaceae and, in particular, to members of the genus Protea. They grow mostly in dry regions of the southern hemisphere, especially in Australia and South Africa. The family is divided into five subfamilies, 75 genera, and 1,350 species. The Proteaceae are distinguished from closely related families by having one…
Proteins are linear chains of amino acids connected by chemical bonds between the carboxyl group of each amino acid and the amine group of the one following. These bonds are called peptide bonds, and chains of only a few amino acids are referred to as polypeptides rather than proteins. Different authorities set the protein/polypeptide dividing line at anywhere from 10 to 100 amino acids. Many prot…
Protest, in the context of this entry, is understood as more or less public visual dissent from an official governmental authority or from customs sanctioned socially by the dominant classes. The protesting voice may be that of a minority or a majority but is here defined, following historiographical and ethical norms, as being directed toward "good causes": democracy, civil rights, …
Protozoa are a very varied group of single-celled organisms, with more than 50,000 different types represented. The vast majority are microscopic, many measuring less than 1/200 mm, but some, such as the freshwater Spirostomun, may reach 0.17 in (3 mm) in length, large enough to enable it to be seen with the naked eye. Scientists have even discovered some fossil specimens that measured 0.78 in (20…
Pseudoscience is a term applied to a field of inquiry by critics claiming that it is a pretended or spurious science because it does not meet established standards. The term pseudoscience is reserved for fields that claim to be a science, that make claims about the world and give explanations of natural processes. Statements of personal values or beliefs are neither scientific nor pseudoscientific…
Psychiatry is the branch of medicine concerned with the study, diagnosis, and treatment of mental illnesses. The word, psychiatry, comes from two Greek words that mean mind healing. Those who practice psychiatry are called psychiatrists. In addition to their M.D.s, these physicians have post-graduate education in the diagnosis and treatment of behaviors that are considered abnormal. They tend to v…
"Psychology" comes from the Greek words psyche, meaning "mind" or "soul," and logos, meaning word. It is the scientific study of human and animal behavior and mental processes. Behavior refers here to easily observable activities such as walking, talking, or smiling. Mental processes, such as thinking, feeling, or remembering, often cannot be directly obse…
Psychiatry in the United States has undergone a number of sweeping changes since the middle of the twentieth century. The settings in which psychiatrists practice, the range of diseases they seek to treat, their theoretical understandings of these diseases, and the treatments they apply are all radically different from those of their predecessors. These changes have had an impact not only on the p…
Psychometry or psychometrics is a field of psychology which uses tests to quantify psychological aptitudes, reactions to stimuli, types of behavior, etc., in an effort to devlop reliable scientific models that can be applied to larger populations. Currently many new psychometric theories and statistical models are being proposed that will probably lead to changes in test construction. In addition,…
A psychotic state is one in which a person suffering from one of several mental illnesses loses touch with reality. People experiencing psychosis may be diagnosed as schizophrenic, manic-depressive, or delusional. Psychosis can also be induced from drug or alcohol abuse, reaction to medication, from exposure to some toxic substance, or from trauma to the brain. Psychotic episodes have a duration t…
Puberty is the period of sexual maturity when sexual organs mature and secondary sexual characteristics develop. Puberty is also the second major growth period of life—the first being infancy. A number of hormones under the control of the hypothalamus, pituitary, ovaries, and testes regulate this period of sexual growth, which begins for most boys and girls between the ages of nine and 15. …
The study of ritual performed in communal life encompasses the wealth of world history and cosmology. Yet, few linguistic or conceptual categories of analysis address fully the diversity of ritual as an enactment of belief in the divine, inclusive of the mythologies of magic, associated with the liminal moments of human experience. For modern societies, the historical celebration of ritual as a dr…
The term public sphere is the English translation of the German term Öffentlichkeit. This term's significance in the late twentieth and early twenty-first century stems initially from its use in Jürgen Habermas's Strukturwandel der Öffentlichkeit (The structural transformation of the public sphere) in 1962. In spite of its foreign origin, the term public sphere actuall…
Puffbirds are 32 species of birds that make up the family Bucconidae. This family is in the order Piciformes, which also contains the woodpeckers, toucans, barbets, jacamars, and honey-guides. Puffbirds are native to lowland tropical forests from southern Mexico, through to Paraguay and northern Argentina in South America. Most species occur in Amazonia. Puffbirds are short, squat birds, with a la…
Puffer fish or globe fish (family Tetraodontidae) are a group of tropical- and warm-temperate-dwelling species that are almost exclusively marine in their habits. A few freshwater species occur in tropical Africa and Asia. Most are typically found in shallow waters, often on coral reefs, in beds of sea grass, and in estuaries, swimming and feeding during daylight. A few species are oceanic. Their …
A pulsar is a celestial object that emits radiation pulses (bursts) of very short (one to a few milliseconds, or thousandths of a second) duration at very regular intervals from a fraction of a second to ten seconds. The first pulsar was discovered in 1967 by Jocelyn Bell and Antony Hewish at Cambridge, England, with radio telescopes equipped to study the twinkling (scintillation) of radio stars. …
Punctuated equilibrium is a theory about how new species evolve that was first advanced by American paleontologists Niles Eldredge and Stephen Jay Gould (1941–2002) in 1972. Although controversial, punctuated equilibrium has stimulated fruitful debate about speciation (the birth of new species) and the fossil record and has, in recent years, won at least partial acceptance among most evolut…
Punishment is best defined as an authorized agent or institution intentionally inflicting pain on an offender or depriving the offender of something in response to an offense or crime the offender is said to have committed. But definitions, however broad, need to be approached with caution, since it is impossible to perfectly capture the myriad constellations of social practices labeled punishment…
Puritanism is the set of religious beliefs and practices retroactively ascribed to Puritans by modern scholars. Since Puritan was originally a term of abuse toward people considered excessively, narrow-mindedly, or hypocritically religious, not an embraced identity, the definitions of both Puritan and Puritanism have been and remain inescapably vague. Roughly, we may take the term Puritans to refe…
A pyramid is a geometric solid of the shape made famous by the royal tombs of ancient Egypt. It is a solid whose base is a polygon and whose lateral faces are triangles with a common vertex (the vertex of the pyramid). In the case of the Egyptian pyramid of Cheops, the base is an almost perfect square 755 ft (230 m) on an edge, and the faces of triangles that are approximately equilateral. Pyr…
This theorem was likely to have been known earlier to be the Babylonians, Pythagoras is said to have traveled to Babylon as a young man, where he could have learned the famous theorem. Nevertheless, Pythagoras (or some member of his school) is credited with the first proof of the theorem. …
The most central teaching of the Pythagorean school—that there is an underlying mathematical structure to the universe—is a foundational idea of Western civilization, particularly in the sciences. Because of this, the entire history of Western scientific and cosmological thought has been intertwined with Pythagorean ideas. Certainly many of the greatest physicists and mathematicians …
Pythons are nonvenomous constricting snakes in the family Boidae that are found only in the Old World. Like the boas, pythons retain lizard-like features such as paired lungs and the remnants of the hind limbs. Pythons are egg-laying snakes which distinguishes them from boas and sandboas which typically bear live young. Fossil species of pythons are known from Cretaceous period, some 200 million y…
Quail are relatively small species of fowl in the family Phasianidae, which also includes pheasants, partridges, peafowl, turkeys, guinea fowl, and francolins. Like other members of their family, quail have a chunky body with short, rounded wings, and a short, thick, hooked bill, in which the tip of the upper mandible hangs slightly over that of the lower. The legs and feet are stout, and are used…
The value of a material is determined in part by the substances of which it is composed. The operations necessary to determine this composition are known as qualitative analysis. Qualitative analysis is a series of tests; responses to these tests identify the elements and compounds that make up the material. Every substance is unique. Each has, for example, a certain color, texture, and appearance…
Quantitative analysis is a chemical analysis performed to find the amount of each component present in a material. It is done by either a classical or instrumental procedure. A quantitative investigation means that the amount (quantity) or relative amount of each component present is determined. In a pure substance, the entire mass, or 100%, is composed of a single component. In materials composed…
The German physicist Max Planck (1858–1947) introduced the quantum of action h (Planck's constant) into physics in his successful theory of blackbody radiation in 1900 and thus started quantum theory, one of several revolutionary discoveries that occurred in physics at the turn of the twentieth century. Others were Albert Einstein's (1879–1955) special theory of relativ…
The computers of today are smaller, faster, and more powerful than their predecessors from the 1940s. The underlying philosophy of the ancient computers and their modern cousins, however, is exactly the same. The task remains the same: to manipulate and interpret information that is expressed as either a 0 or a 1. This packaging of information is referred to as the binary bit. Binary bit computers…
Quantum electrodynamics (QED) is a complex and highly mathematical theory regarding the interaction of electromagnetic radiation with matter. The development of QED theory was essential in the verification and development of quantum field theory and it allows physicists to predict how subatomic particles are created or destroyed. QED is a fundamentally important scientific theory that accounts for…
Quantum mechanics is the theory used to provide an understanding of the behavior of microscopic particles such as electrons and atoms. More importantly, quantum mechanics describes the relationships between energy and matter on atomic and subatomic scale. At the beginning of the twentieth century, German physicist Maxwell Planck (1858–1947) proposed that atoms absorb or emit electromagnetic…
A quantum number is a number that specifies the particular state of motion an atom or molecule is in and, usually, the energy of that motion. By 1900, several phenomena were recognized that could not be explained by accepted scientific theories. One such phenomenon was the behavior of light itself. In 1900, however, Max Planck (1858-1947) developed a new theory that successfully described the natu…