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The idea that, in the first split-second after the Big Bang, the universe underwent a fantastically fast (exponential) expansion driven by the vacuum of empty space. The theory was developed by Alan Guth in the early 1980s to explain certain problems and inconsistencies with the basic Big Bang theory, such as those related to the large-scale structure of the features of the universe, the ...
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“God and the New Physics” by Paul Davies (Penguin, 1983) “A...
- Hawking, Stephen
Stephen Hawking is a world-renowned British theoretical...
- A Few Random Facts
The Physics of the Universe - A Few Random Facts. Main...
- Black Holes and Wormholes
Black holes are a phenomenon predicted by Albert Einstein's...
- Alexander Oparin
Alexander Oparin was a Russian biochemist, notable for his...
- Bohr, Niels
Niels Bohr was a Danish physicist who made fundamental...
- Pauli, Wolfgang
In 1945, he received the Nobel Prize in Physics (nominated...
- Important Scientists
Although the development of modern physics owes a huge debt...
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A Dictionary of Physics (6 ed.) This is the most popular dictionary of physics available. It contains over 3,800 entries covering all commonly encountered physics terms and concepts, as well as terms from the related fields of astronomy, astrophysics, and physical chemistry. With 200 new entries and expanded coverage in areas including applied ...
Glossary of Physics Terms. Absolute humidity (or Saturation value) The maximum amount of water vapor, which could be present in 1 m³ of the air at any given temperature, is called absolute humidity. Absolute magnitude A classification scheme, which compensates for the distance, differences to stars.
The meaning of COUTH is sophisticated, polished. How to use couth in a sentence.
- Overview
- The scope of physics
- Mechanics
Physics is the branch of science that deals with the structure of matter and how the fundamental constituents of the universe interact. It studies objects ranging from the very small using quantum mechanics to the entire universe using general relativity.
Why does physics work in SI units?
Physicists and other scientists use the International System of Units (SI) in their work because they wish to use a system that is agreed upon by scientists worldwide. Since 2019 the SI units have been defined in terms of fundamental physical constants, which means that scientists anywhere using SI can agree upon the units they use to measure physical phenomena.
physics, science that deals with the structure of matter and the interactions between the fundamental constituents of the observable universe. In the broadest sense, physics (from the Greek physikos) is concerned with all aspects of nature on both the macroscopic and submicroscopic levels. Its scope of study encompasses not only the behaviour of objects under the action of given forces but also the nature and origin of gravitational, electromagnetic, and nuclear force fields. Its ultimate objective is the formulation of a few comprehensive principles that bring together and explain all such disparate phenomena.
(Read Einstein’s 1926 Britannica essay on space-time.)
Physics is the basic physical science. Until rather recent times physics and natural philosophy were used interchangeably for the science whose aim is the discovery and formulation of the fundamental laws of nature. As the modern sciences developed and became increasingly specialized, physics came to denote that part of physical science not included in astronomy, chemistry, geology, and engineering. Physics plays an important role in all the natural sciences, however, and all such fields have branches in which physical laws and measurements receive special emphasis, bearing such names as astrophysics, geophysics, biophysics, and even psychophysics. Physics can, at base, be defined as the science of matter, motion, and energy. Its laws are typically expressed with economy and precision in the language of mathematics.
The traditionally organized branches or fields of classical and modern physics are delineated below.
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Mechanics is generally taken to mean the study of the motion of objects (or their lack of motion) under the action of given forces. Classical mechanics is sometimes considered a branch of applied mathematics. It consists of kinematics, the description of motion, and dynamics, the study of the action of forces in producing either motion or static equilibrium (the latter constituting the science of statics). The 20th-century subjects of quantum mechanics, crucial to treating the structure of matter, subatomic particles, superfluidity, superconductivity, neutron stars, and other major phenomena, and relativistic mechanics, important when speeds approach that of light, are forms of mechanics that will be discussed later in this section.
In classical mechanics the laws are initially formulated for point particles in which the dimensions, shapes, and other intrinsic properties of bodies are ignored. Thus in the first approximation even objects as large as Earth and the Sun are treated as pointlike—e.g., in calculating planetary orbital motion. In rigid-body dynamics, the extension of bodies and their mass distributions are considered as well, but they are imagined to be incapable of deformation. The mechanics of deformable solids is elasticity; hydrostatics and hydrodynamics treat, respectively, fluids at rest and in motion.
The three laws of motion set forth by Isaac Newton form the foundation of classical mechanics, together with the recognition that forces are directed quantities (vectors) and combine accordingly. The first law, also called the law of inertia, states that, unless acted upon by an external force, an object at rest remains at rest, or if in motion, it continues to move in a straight line with constant speed. Uniform motion therefore does not require a cause. Accordingly, mechanics concentrates not on motion as such but on the change in the state of motion of an object that results from the net force acting upon it. Newton’s second law equates the net force on an object to the rate of change of its momentum, the latter being the product of the mass of a body and its velocity. Newton’s third law, that of action and reaction, states that when two particles interact, the forces each exerts on the other are equal in magnitude and opposite in direction. Taken together, these mechanical laws in principle permit the determination of the future motions of a set of particles, providing their state of motion is known at some instant, as well as the forces that act between them and upon them from the outside. From this deterministic character of the laws of classical mechanics, profound (and probably incorrect) philosophical conclusions have been drawn in the past and even applied to human history.
Lying at the most basic level of physics, the laws of mechanics are characterized by certain symmetry properties, as exemplified in the aforementioned symmetry between action and reaction forces. Other symmetries, such as the invariance (i.e., unchanging form) of the laws under reflections and rotations carried out in space, reversal of time, or transformation to a different part of space or to a different epoch of time, are present both in classical mechanics and in relativistic mechanics, and with certain restrictions, also in quantum mechanics. The symmetry properties of the theory can be shown to have as mathematical consequences basic principles known as conservation laws, which assert the constancy in time of the values of certain physical quantities under prescribed conditions. The conserved quantities are the most important ones in physics; included among them are mass and energy (in relativity theory, mass and energy are equivalent and are conserved together), momentum, angular momentum, and electric charge.
Apply physics to describe the function of daily life. Physics is a natural science that involves the study of matter and its motion through space and time, along with related concepts such as energy and force. More broadly, it is the study of nature in an attempt to understand how the universe behaves.
Voltage. Voltage. close. voltage The potential difference across a cell, electrical supply or electrical component. It is measured in volts (V). is a measure of the difference in electrical energy ...
