Physics is the fundamental branch of science that developed out of the study of nature and philosophy known, until around the end of the 19th century, as "natural philosophy." Today, physics is ultimately defined as the study of matter, energy and the relationships between them. Physics is, in some senses, the oldest and most basic pure science; its discoveries find applications throughout the natural sciences, since matter and energy are the basic constituents of the natural world. The other sciences are generally more limited in their scope and may be considered branches that have split off...

The human genome is the complete set of nucleic acid sequence for humans (Homo sapiens), encoded as DNA within the 23chromosome pairs in cell nuclei and in a small DNA molecule found within individual mitochondria. Human genomes include both protein-coding DNA genes and noncoding DNA. Haploid human genomes, which are contained in germ cells (the egg and spermgamete cells created in the meiosis phase of sexual reproduction before fertilization creates a zygote) consist of three billion DNAbase pairs, while diploid genomes (found in somatic cells) have twice the DNA content. While there are...

Physics is the fundamental branch of science that developed out of the study of nature and philosophy known, until around the end of the 19th century, as "natural philosophy." Today, physics is ultimately defined as the study of matter, energy and the relationships between them. Physics is, in some senses, the oldest and most basic pure science; its discoveries find applications throughout the natural sciences, since matter and energy are the basic constituents of the natural world. The other sciences are generally more limited in their scope and may be considered branches that have split off...

Wave-particle duality is the concept that every elementary particle or quantic entity may be partly described in terms not only of particles, but also of waves. It expresses the inability of the classical concepts "particle" or "wave" to fully describe the behavior of quantum-scale objects. As Einstein wrote: "It seems as though we must use sometimes the one theory and sometimes the other, while at times we may use either. We are faced with a new kind of difficulty. We have two contradictory pictures of reality; separately neither of them fully explains the phenomena of light, but together...

There is a natural connection between particle physics and representation theory, as first noted in the 1930s by Eugene Wigner. It links the properties of elementary particles to the structure of Lie groups and Lie algebras. According to this connection, the different quantum states of an elementary particle give rise to an irreducible representation of the Poincare group. Moreover, the properties of the various particles, including their spectra, can be related to representations of Lie algebras, corresponding to "approximate symmetries" of the universe. In quantum mechanics, any particular...

Psychotherapy is the use of psychological methods, particularly when based on regular personal interaction, to help a person change and overcome problems in desired ways. Psychotherapy aims to increase each individual's well-being and mental health, to resolve or mitigate troublesome behaviors, beliefs, compulsions, thoughts, or emotions, and to improve relationships and social functioning. Certain psychotherapies are considered evidence-based for treating some diagnosed mental disorders. There are over a thousand different named psychotherapies, some being minor variations while others are...

A parable is a succinct, didactic story, in prose or verse, which illustrates one or more instructive lessons or principles. The parable differs from a fable in that fables employ animals, plants, inanimate objects or forces of nature as characters, whereas parables have human characters. A parable is a type of analogy. Some scholars of the canonical gospels and the New Testament apply the term "parable" only to the parables of Jesus, though that is not a common restriction of the term. Parables such as "The Prodigal Son" are central to Jesus' teaching method in the canonical narratives and...

A molecule is an electrically neutral group of two or more atoms held together by chemical bonds. Molecules are distinguished from ions by their lack of electrical charge. However, in quantum physics, organic chemistry, and biochemistry, the term molecule is often used less strictly, also being applied to polyatomic ions. In the kinetic theory of gases, the term molecule is often used for any gaseous particle regardless of its composition. According to this de nition, noble gas atoms are considered molecules despite being composed of a single non-bonded atom. A molecule may be homonuclear,...

This introduction to ballistics is an overview of the essentials involved in the mathematical modeling of the ballistics that pertain to a bullet that is fired from a firearm. This book gives an overview into the classical mechanics of ballistics which includes everything from the internal, transitional, external and terminal ballistics to the equations of motion, trajectory, hydrostatic shock and Stokes' Law. Included are sections on ranged weapons, propellants, firearm, bullet and barrel design. A section on stopping power is especially noteworthy as this is often the factor that drives the...

Edgar Allen Poe is a famous american author known worldwide. Edgar Allan Poe, born Edgar Poe; (January 19, 1809 - October 7, 1849) was an American author, poet, editor, and literary critic. Poe's works were considered part of the American Romantic Movement. Best known for his tales of mystery and the macabre, Poe was one of the earliest American practitioners of the short story, and is generally considered the inventor of the detective fiction genre. He is further credited with contributing to the emerging genre of science fiction. He was the first well-known American writer to try to earn a...