Physics (from the Ancient Greek φύσις physis meaning "nature") 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.[citation needed] 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 from physics to become sciences in their own right. Physics today may be divided loosely into classical physics and modern physics.
In 1714, Brook Taylor derived the fundamental frequency of a stretched vibrating string in terms of its tension and mass per unit length by solving a differential equation. The Swiss mathematician Daniel Bernoulli (1700–1782) made important mathematical studies of the behavior of gases, anticipating the kinetic theory of gases developed more than a century later, and has been referred to as the first mathematical physicist.[28] In 1733, Daniel Bernoulli derived the fundamental frequency and harmonics of a hanging chain by solving a differential equation. In 1734, Bernoulli solved the differential equation for the vibrations of an elastic bar clamped at one end. Bernoulli's treatment of fluid dynamics and his examination of fluid flow was introduced in his 1738 work Hydrodynamica.
Rational mechanics dealt primarily with the development of elaborate mathematical treatments of observed motions, using Newtonian principles as a basis, and emphasized improving the tractability of complex calculations and developing of legitimate means of analytical approximation. A representative contemporary textbook was published by Johann Baptiste Horvath. By the end of the century analytical treatments were rigorous enough to verify the stability of the solar system solely on the basis of Newton's laws without reference to divine intervention—even as deterministic treatments of systems as simple as the three body problem in gravitation remained intractable.[29] In 1705, Edmond Halley predicted the periodicity of Halley's Comet, William Herschel discovered Uranus in 1781, and Henry Cavendish measured the gravitational constant and determined the mass of the Earth in 1798. In 1783, John Michell suggested that some objects might be so massive that not even light could escape from them.
In 1739, Leonhard Euler solved the ordinary differential equation for a forced harmonic oscillator and noticed the resonance phenomenon. In 1742, Colin Maclaurin discovered his uniformly rotating self-gravitating spheroids. British work, carried on by mathematicians such as Taylor and Maclaurin, fell behind Continental developments as the century progressed. Meanwhile, work flourished at scientific academies on the Continent, led by such mathematicians as Bernoulli, Euler, Lagrange, Laplace, and Legendre. In 1743, Jean le Rond d'Alembert published his "Traite de Dynamique", in which he introduces the concept of generalized forces for accelerating systems and systems with constraints. In 1747, Pierre Louis Maupertuis applied minimum principles to mechanics. In 1759, Euler solved the partial differential equation for the vibration of a rectangular drum. In 1764, Euler examined the partial differential equation for the vibration of a circular drum and found one of the Bessel function solutions. In 1776, John Smeaton published a paper on experiments relating power, work, momentum and kinetic energy, and supporting the conservation of energy. In 1788, Joseph Louis Lagrange presented Lagrange's equations of motion in Mécanique Analytique. In 1789, Antoine Lavoisier states the law of conservation of mass. Newton's mechanics received brilliant exposition in both Lagrange's 1788 work and the Celestial Mechanics (1799–1825) of Pierre-Simon Laplace.
During the 18th century, thermodynamics was developed through the theories of weightless "imponderable fluids", such as heat ("caloric"), electricity, and phlogiston (which was rapidly overthrown as a concept following Lavoisier's identification of oxygen gas late in the century). Assuming that these concepts were real fluids, their flow could be traced through a mechanical apparatus or chemical reactions. This tradition of experimentation led to the development of new kinds of experimental apparatus, such as the Leyden Jar; and new kinds of measuring instruments, such as the calorimeter, and improved versions of old ones, such as the thermometer. Experiments also produced new concepts, such as the University of Glasgow experimenter Joseph Black's notion of latent heat and Philadelphia intellectual Benjamin Franklin's characterization of electrical fluid as flowing between places of excess and deficit (a concept later reinterpreted in terms of positive and negative charges). Franklin also showed that lightning is electricity in 1752.
The accepted theory of heat in the 18th century viewed it as a kind of fluid, called caloric; although this theory was later shown to be erroneous, a number of scientists adhering to it nevertheless made important discoveries useful in developing the modern theory, including Joseph Black (1728–99) and Henry Cavendish (1731–1810). Opposed to this caloric theory, which had been developed mainly by the chemists, was the less accepted theory dating from Newton's time that heat is due to the motions of the particles of a substance. This mechanical theory gained support in 1798 from the cannon-boring experiments of Count Rumford (Benjamin Thompson), who found a direct relationship between heat and mechanical energy.
While it was recognized early in the 18th century that finding absolute theories of electrostatic and magnetic force akin to Newton's principles of motion would be an important achievement, none were forthcoming. This impossibility only slowly disappeared as experimental practice became more widespread and more refined in the early years of the 19th century in places such as the newly established Royal Institution in London. Meanwhile, the analytical methods of rational mechanics began to be applied to experimental phenomena, most influentially with the French mathematician Joseph Fourier's analytical treatment of the flow of heat, as published in 1822.[30][31][32] Joseph Priestley proposed an electrical inverse-square law in 1767, and Charles-Augustin de Coulomb introduced the inverse-square law of electrostatics in 1798.
At the end of the century, the members of the French Academy of Sciences had attained clear dominance in the field.[24][33][34][35] At the same time, the experimental tradition established by Galileo and his followers persisted. The Royal Society and the French Academy of Sciences were major centers for the performance and reporting of experimental work. Experiments in mechanics, optics, magnetism, static electricity, chemistry, and physiology were not clearly distinguished from each other during the 18th century, but significant differences in explanatory schemes and, thus, experiment design were emerging. Chemical experimenters, for instance, defied attempts to enforce a scheme of abstract Newtonian forces onto chemical affiliations, and instead focused on the isolation and classification of chemical substances and reactions.[36]
The film "Interstellar" relies on real science for many of its stunning visuals. Physicist Kip Thorne, an expert on black holes and wormholes, provided the math that the special effects artists turned into movie magic. The spaceship Endurance's destination is Gargantua, a fictional supermassive black hole with a mass 100 million times that of the sun. It lies 10 billion light-years from Earth and is orbited by several planets. Gargantua rotates at an astounding 99.8 percent of the speed of light. "Interstellar" in Pictures: A Space Epic Gallery Gargantua's accretion disc contains gas and dust with the temperature of the surface of the sun. The disc provides light and heat to Gargantua's planets. The black hole's complex appearance in the film is due to the image of the accretion disc being warped by gravitational lensing into two images: one looping over the black hole and the other under it. One feature of Einstein's equations is that time passes slower in higher gravity fields. So on a planet orbiting close to a black hole, a clock ticks much more slowly than on a spaceship orbiting farther away. Warp Drives & Wormholes (Video) Our three-dimensional universe can be thought of as a flat membrane (or "brane") floating in a four-dimensional void called the "Bulk." The presence of mass distorts the membrane as if it were a rubber sheet. If enough mass is concentrated at a point, a singularity is formed. Objects approaching the singularity pass through an event horizon from which they can never return. If two singularities in far-apart locations could be merged, a wormhole tunnel through the Bulk could be formed. Such wormholes cannot form naturally, however. Beings able to control gravity and travel through the Bulk could create wormholes and cross space much faster than light. In two-dimensional diagrams, the wormhole mouth is shown as a circle. Seen in person, a wormhole would be a sphere. A gravitationally distorted view of space on the other side can be seen on the sphere's surface. The film's wormhole is 1.25 miles (2 kilometers) in diameter and 10 billion light-years long.
The history of the world (or world history) is the history of humanity (as opposed to the history of Earth), beginning with the Paleolithic Era. World history comprises the study of archaeological and written records, from ancient times on. Ancient recorded history begins with the invention of writing.[2][3] However, the roots of civilization reach back to the period before the invention of writing. Prehistory begins in the Paleolithic Era, or "Early Stone Age," which is followed by the Neolithic Era, or New Stone Age, and the Agricultural Revolution (between 8000 and 5000 BCE) in the Fertile Crescent. The Agricultural Revolution marked a change in human history, as humans began the systematic husbandry of plants and animals.[4][5][6] Agriculture advanced, and most humans transitioned from a nomadic to a settled lifestyle as farmers in permanent settlements. Nomadism continued in some locations, especially in isolated regions with few domesticable plant species;[7] but the relative security and increased productivity provided by farming allowed human communities to expand into increasingly larger units, fostered by advances in transportation.
As farming developed, grain agriculture became more sophisticated and prompted a division of labor to store food between growing seasons. Labor divisions then led to the rise of a leisured upper class and the development of cities. The growing complexity of human societies necessitated systems of writing and accounting.[8] Many cities developed on the banks of lakes and rivers; as early as 3000 BCE some of the first prominent, well-developed settlements had arisen in Mesopotamia,[9] on the banks of Egypt's River Nile,[10][11][12] Indus River valley,[13][14][15] and major rivers in China[16][17][18]
The history of the Old World (particularly Europe and the Mediterranean) is commonly divided into Ancient history (or "Antiquity"), up to 476 AD; the Postclassical Era (or "Middle Ages"[19][20]), from the 5th through 15th centuries, including the Islamic Golden Age (c. 750 CE – c. 1258 CE) and the early European Renaissance (beginning around 1300 CE);[21][22] the Early Modern period,[23] from the 15th century to the late 18th, including the Age of Enlightenment; and the Late Modern period, from the Industrial Revolution to the present, including Contemporary History. The ancient Near East,[24][25][26] ancient Greece, and ancient Rome figure prominently in the period of Antiquity. In the history of Western Europe, the fall in 476 CE of Romulus Augustulus, by some reckonings the last western Roman emperor, is commonly taken as signaling the end of Antiquity and the start of the Middle Ages. By contrast, Eastern Europe saw a transition from the Roman Empire to the Byzantine Empire, which did not decline until much later. In the mid-15th century, Johannes Gutenberg's invention of modern printing,[27] employing movable type, revolutionized communication, helping end the Middle Ages and usher in the Scientific Revolution.[28] By the 18th century, the accumulation of knowledge and technology, especially in Europe, had reached a critical mass that brought about the Industrial Revolution.[29]
Outside the Old World, including ancient China[30] and ancient India, historical timelines unfolded differently. By the 18th century, however, due to extensive world trade and colonization, the histories of most civilizations had become substantially intertwined (see Globalization). In the last quarter-millennium, the rate of growth of population, knowledge, technology, commerce, weapons destructiveness and environmental degradation has greatly accelerated, creating opportunities and perils that now confront the planet's human communities.[31][32]
The chicken or the egg causality dilemma is commonly stated as "which came first, the chicken or the egg?" To ancient philosophers, the question about the first chicken or egg also evoked the questions of how life and the universe in general began.[1]
From a modern scientific perspective, the chicken came first because the genetic recombination that produced the first "chicken" (though that may be an arbitrary definition in a breeding population undergoing speciation) occurred in germ-line cells in a non-chicken ancestor. Another literal answer is that "the egg" in general came first, because egg-laying species pre-date the existence of chickens. To others, the chicken came first, seeing as chickens are merely domesticated red junglefowls.[citation needed]
Cultural references to the chicken and egg intend to point out the futility of identifying the first case of a circular cause and consequence. The metaphorical view sets a metaphysical ground to the dilemma. To better understand its metaphorical meaning, the question could be reformulated as: "Which came first, X that can't come without Y, or Y that can't come without X?"
An equivalent situation arises in engineering and science known as circular reference, in which a parameter is required to calculate that parameter itself. Examples are Van der Waals equation and the Colebrook equation[citation needed].
Physics (from the Ancient Greek φύσις physis meaning "nature") 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.[citation needed] 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 from physics to become sciences in their own right. Physics today may be divided loosely into classical physics and modern physics.
ReplyDeleteIn 1714, Brook Taylor derived the fundamental frequency of a stretched vibrating string in terms of its tension and mass per unit length by solving a differential equation. The Swiss mathematician Daniel Bernoulli (1700–1782) made important mathematical studies of the behavior of gases, anticipating the kinetic theory of gases developed more than a century later, and has been referred to as the first mathematical physicist.[28] In 1733, Daniel Bernoulli derived the fundamental frequency and harmonics of a hanging chain by solving a differential equation. In 1734, Bernoulli solved the differential equation for the vibrations of an elastic bar clamped at one end. Bernoulli's treatment of fluid dynamics and his examination of fluid flow was introduced in his 1738 work Hydrodynamica.
ReplyDeleteRational mechanics dealt primarily with the development of elaborate mathematical treatments of observed motions, using Newtonian principles as a basis, and emphasized improving the tractability of complex calculations and developing of legitimate means of analytical approximation. A representative contemporary textbook was published by Johann Baptiste Horvath. By the end of the century analytical treatments were rigorous enough to verify the stability of the solar system solely on the basis of Newton's laws without reference to divine intervention—even as deterministic treatments of systems as simple as the three body problem in gravitation remained intractable.[29] In 1705, Edmond Halley predicted the periodicity of Halley's Comet, William Herschel discovered Uranus in 1781, and Henry Cavendish measured the gravitational constant and determined the mass of the Earth in 1798. In 1783, John Michell suggested that some objects might be so massive that not even light could escape from them.
In 1739, Leonhard Euler solved the ordinary differential equation for a forced harmonic oscillator and noticed the resonance phenomenon. In 1742, Colin Maclaurin discovered his uniformly rotating self-gravitating spheroids. British work, carried on by mathematicians such as Taylor and Maclaurin, fell behind Continental developments as the century progressed. Meanwhile, work flourished at scientific academies on the Continent, led by such mathematicians as Bernoulli, Euler, Lagrange, Laplace, and Legendre. In 1743, Jean le Rond d'Alembert published his "Traite de Dynamique", in which he introduces the concept of generalized forces for accelerating systems and systems with constraints. In 1747, Pierre Louis Maupertuis applied minimum principles to mechanics. In 1759, Euler solved the partial differential equation for the vibration of a rectangular drum. In 1764, Euler examined the partial differential equation for the vibration of a circular drum and found one of the Bessel function solutions. In 1776, John Smeaton published a paper on experiments relating power, work, momentum and kinetic energy, and supporting the conservation of energy. In 1788, Joseph Louis Lagrange presented Lagrange's equations of motion in Mécanique Analytique. In 1789, Antoine Lavoisier states the law of conservation of mass. Newton's mechanics received brilliant exposition in both Lagrange's 1788 work and the Celestial Mechanics (1799–1825) of Pierre-Simon Laplace.
During the 18th century, thermodynamics was developed through the theories of weightless "imponderable fluids", such as heat ("caloric"), electricity, and phlogiston (which was rapidly overthrown as a concept following Lavoisier's identification of oxygen gas late in the century). Assuming that these concepts were real fluids, their flow could be traced through a mechanical apparatus or chemical reactions. This tradition of experimentation led to the development of new kinds of experimental apparatus, such as the Leyden Jar; and new kinds of measuring instruments, such as the calorimeter, and improved versions of old ones, such as the thermometer. Experiments also produced new concepts, such as the University of Glasgow experimenter Joseph Black's notion of latent heat and Philadelphia intellectual Benjamin Franklin's characterization of electrical fluid as flowing between places of excess and deficit (a concept later reinterpreted in terms of positive and negative charges). Franklin also showed that lightning is electricity in 1752.
ReplyDeleteThe accepted theory of heat in the 18th century viewed it as a kind of fluid, called caloric; although this theory was later shown to be erroneous, a number of scientists adhering to it nevertheless made important discoveries useful in developing the modern theory, including Joseph Black (1728–99) and Henry Cavendish (1731–1810). Opposed to this caloric theory, which had been developed mainly by the chemists, was the less accepted theory dating from Newton's time that heat is due to the motions of the particles of a substance. This mechanical theory gained support in 1798 from the cannon-boring experiments of Count Rumford (Benjamin Thompson), who found a direct relationship between heat and mechanical energy.
While it was recognized early in the 18th century that finding absolute theories of electrostatic and magnetic force akin to Newton's principles of motion would be an important achievement, none were forthcoming. This impossibility only slowly disappeared as experimental practice became more widespread and more refined in the early years of the 19th century in places such as the newly established Royal Institution in London. Meanwhile, the analytical methods of rational mechanics began to be applied to experimental phenomena, most influentially with the French mathematician Joseph Fourier's analytical treatment of the flow of heat, as published in 1822.[30][31][32] Joseph Priestley proposed an electrical inverse-square law in 1767, and Charles-Augustin de Coulomb introduced the inverse-square law of electrostatics in 1798.
At the end of the century, the members of the French Academy of Sciences had attained clear dominance in the field.[24][33][34][35] At the same time, the experimental tradition established by Galileo and his followers persisted. The Royal Society and the French Academy of Sciences were major centers for the performance and reporting of experimental work. Experiments in mechanics, optics, magnetism, static electricity, chemistry, and physiology were not clearly distinguished from each other during the 18th century, but significant differences in explanatory schemes and, thus, experiment design were emerging. Chemical experimenters, for instance, defied attempts to enforce a scheme of abstract Newtonian forces onto chemical affiliations, and instead focused on the isolation and classification of chemical substances and reactions.[36]
The film "Interstellar" relies on real science for many of its stunning visuals. Physicist Kip Thorne, an expert on black holes and wormholes, provided the math that the special effects artists turned into movie magic.
ReplyDeleteThe spaceship Endurance's destination is Gargantua, a fictional supermassive black hole with a mass 100 million times that of the sun. It lies 10 billion light-years from Earth and is orbited by several planets. Gargantua rotates at an astounding 99.8 percent of the speed of light.
"Interstellar" in Pictures: A Space Epic Gallery
Gargantua's accretion disc contains gas and dust with the temperature of the surface of the sun. The disc provides light and heat to Gargantua's planets.
The black hole's complex appearance in the film is due to the image of the accretion disc being warped by gravitational lensing into two images: one looping over the black hole and the other under it.
One feature of Einstein's equations is that time passes slower in higher gravity fields. So on a planet orbiting close to a black hole, a clock ticks much more slowly than on a spaceship orbiting farther away.
Warp Drives & Wormholes (Video)
Our three-dimensional universe can be thought of as a flat membrane (or "brane") floating in a four-dimensional void called the "Bulk." The presence of mass distorts the membrane as if it were a rubber sheet.
If enough mass is concentrated at a point, a singularity is formed. Objects approaching the singularity pass through an event horizon from which they can never return. If two singularities in far-apart locations could be merged, a wormhole tunnel through the Bulk could be formed. Such wormholes cannot form naturally, however.
Beings able to control gravity and travel through the Bulk could create wormholes and cross space much faster than light.
In two-dimensional diagrams, the wormhole mouth is shown as a circle. Seen in person, a wormhole would be a sphere. A gravitationally distorted view of space on the other side can be seen on the sphere's surface.
The film's wormhole is 1.25 miles (2 kilometers) in diameter and 10 billion light-years long.
The history of the world (or world history) is the history of humanity (as opposed to the history of Earth), beginning with the Paleolithic Era. World history comprises the study of archaeological and written records, from ancient times on. Ancient recorded history begins with the invention of writing.[2][3] However, the roots of civilization reach back to the period before the invention of writing. Prehistory begins in the Paleolithic Era, or "Early Stone Age," which is followed by the Neolithic Era, or New Stone Age, and the Agricultural Revolution (between 8000 and 5000 BCE) in the Fertile Crescent. The Agricultural Revolution marked a change in human history, as humans began the systematic husbandry of plants and animals.[4][5][6] Agriculture advanced, and most humans transitioned from a nomadic to a settled lifestyle as farmers in permanent settlements. Nomadism continued in some locations, especially in isolated regions with few domesticable plant species;[7] but the relative security and increased productivity provided by farming allowed human communities to expand into increasingly larger units, fostered by advances in transportation.
ReplyDeleteAs farming developed, grain agriculture became more sophisticated and prompted a division of labor to store food between growing seasons. Labor divisions then led to the rise of a leisured upper class and the development of cities. The growing complexity of human societies necessitated systems of writing and accounting.[8] Many cities developed on the banks of lakes and rivers; as early as 3000 BCE some of the first prominent, well-developed settlements had arisen in Mesopotamia,[9] on the banks of Egypt's River Nile,[10][11][12] Indus River valley,[13][14][15] and major rivers in China[16][17][18]
The history of the Old World (particularly Europe and the Mediterranean) is commonly divided into Ancient history (or "Antiquity"), up to 476 AD; the Postclassical Era (or "Middle Ages"[19][20]), from the 5th through 15th centuries, including the Islamic Golden Age (c. 750 CE – c. 1258 CE) and the early European Renaissance (beginning around 1300 CE);[21][22] the Early Modern period,[23] from the 15th century to the late 18th, including the Age of Enlightenment; and the Late Modern period, from the Industrial Revolution to the present, including Contemporary History. The ancient Near East,[24][25][26] ancient Greece, and ancient Rome figure prominently in the period of Antiquity. In the history of Western Europe, the fall in 476 CE of Romulus Augustulus, by some reckonings the last western Roman emperor, is commonly taken as signaling the end of Antiquity and the start of the Middle Ages. By contrast, Eastern Europe saw a transition from the Roman Empire to the Byzantine Empire, which did not decline until much later. In the mid-15th century, Johannes Gutenberg's invention of modern printing,[27] employing movable type, revolutionized communication, helping end the Middle Ages and usher in the Scientific Revolution.[28] By the 18th century, the accumulation of knowledge and technology, especially in Europe, had reached a critical mass that brought about the Industrial Revolution.[29]
Outside the Old World, including ancient China[30] and ancient India, historical timelines unfolded differently. By the 18th century, however, due to extensive world trade and colonization, the histories of most civilizations had become substantially intertwined (see Globalization). In the last quarter-millennium, the rate of growth of population, knowledge, technology, commerce, weapons destructiveness and environmental degradation has greatly accelerated, creating opportunities and perils that now confront the planet's human communities.[31][32]
The chicken or the egg causality dilemma is commonly stated as "which came first, the chicken or the egg?" To ancient philosophers, the question about the first chicken or egg also evoked the questions of how life and the universe in general began.[1]
ReplyDeleteFrom a modern scientific perspective, the chicken came first because the genetic recombination that produced the first "chicken" (though that may be an arbitrary definition in a breeding population undergoing speciation) occurred in germ-line cells in a non-chicken ancestor. Another literal answer is that "the egg" in general came first, because egg-laying species pre-date the existence of chickens. To others, the chicken came first, seeing as chickens are merely domesticated red junglefowls.[citation needed]
Cultural references to the chicken and egg intend to point out the futility of identifying the first case of a circular cause and consequence. The metaphorical view sets a metaphysical ground to the dilemma. To better understand its metaphorical meaning, the question could be reformulated as: "Which came first, X that can't come without Y, or Y that can't come without X?"
An equivalent situation arises in engineering and science known as circular reference, in which a parameter is required to calculate that parameter itself. Examples are Van der Waals equation and the Colebrook equation[citation needed].