Status
Main article: Status of special relativity Special relativity is usually concerned with the behaviour of objects and "observers" (inertial reference systems) which remain at rest or are moving at a constant velocity. In this case, the observer is said to be in an inertial frame of reference. Comparison of the position and time of events as recorded by different inertial observersSpecial relativity is accurate only when gravitational potential In celestial mechanics, the gravitational potential is a scalar field created by any mass, such as the earth or the Sun. The potential at a distance r from a point mass M is given by is much less than c2; in a strong gravitational field one must use general relativity General relativity or the general theory of relativity is the geometric theory of gravitation published by Albert Einstein in 1916. It is the current description of gravitation in modern physics. It unifies special relativity and Newton's law of universal gravitation, and describes gravity as a geometric property of space and time, or spacetime (which becomes special relativity at the limit of weak field). At very small scales, such as at the Planck length In physics, the Planck length, denoted , is a unit of length, equal to 1.616252×10−35 meters. It is a base unit in the system of Planck units. The Planck length can be defined from three fundamental physical constants: the speed of light in a vacuum, Planck's constant, and the gravitational constant. Current theory suggests that one Planck and below, quantum effects must be taken into consideration resulting in quantum gravity Quantum gravity is the field of theoretical physics attempting to unify quantum mechanics with general relativity in a self-consistent manner, or more precisely, to formulate a self-consistent theory which reduces to ordinary quantum mechanics in the limit of weak gravity (potentials much less than c2) and which reduces to "classical". However, at macroscopic scales and in the absence of strong gravitational fields, special relativity is experimentally tested to extremely high degree of accuracy (10–20)[48] and thus accepted by the physics community. Experimental results which appear to contradict it are not reproducible and are thus widely believed to be due to experimental errors.
Special relativity is mathematically self-consistent, and it is an organic part of all modern physical theories, most notably quantum field theory Quantum field theory or QFT provides a theoretical framework for constructing quantum mechanical models of systems classically described by fields or of many-body systems. It is widely used in particle physics and condensed matter physics. Most theories in modern particle physics, including the Standard Model of elementary particles and their, string theory String theory is a developing branch of theoretical physics that combines quantum mechanics and general relativity into a quantum theory of gravity. The strings of string theory are one-dimensional oscillating lines, but they are no longer considered fundamental to the theory, which can be formulated in points or surfaces too, and general relativity (in the limiting case of negligible gravitational fields).
Newtonian mechanics mathematically follows from special relativity at small velocities (compared to the speed of light) — thus Newtonian mechanics can be considered as a special relativity of slow moving bodies. See Status of special relativity Special relativity is usually concerned with the behaviour of objects and "observers" (inertial reference systems) which remain at rest or are moving at a constant velocity. In this case, the observer is said to be in an inertial frame of reference. Comparison of the position and time of events as recorded by different inertial observers for a more detailed discussion.
Several experiments predating Einstein's 1905 paper are now interpreted as evidence for relativity. (Of these, Einstein was only aware of the Fizeau experiment before 1905.)
- The Trouton–Noble experiment showed that the torque on a capacitor is independent of position and inertial reference frame.
- The famous Michelson-Morley experiment The Michelson-Morley experiment was performed in 1887 by Albert Michelson and Edward Morley at what is now Case Western Reserve University. It is generally considered to be the first strong evidence against the theory of a luminiferous aether. The experiment has also been referred to as "the kicking-off point for the theoretical aspects of gave further support to the postulate that detecting an absolute reference velocity was not achievable. It should be stated here that, contrary to many alternative claims, it said little about the invariance of the speed of light with respect to the source and observer's velocity, as both source and observer were travelling together at the same velocity at all times.
- The Fizeau experiment The Fizeau experiment was carried out by Hippolyte Fizeau in the 1851 to measure the relative speeds of light in moving water. Albert Einstein later pointed out the importance of the experiment for special relativity measured the speed of light in moving media, with results that are consistent with relativistic addition of velocities.
A number of experiments have been conducted to test special relativity against rival theories. These include:
- Kaufmann-Bucherer-Neumann Walter Kaufmann was a German physicist. He is most well-known for his first experimental proof of the velocity dependence of mass, which was an important contribution to the development of modern physics, including special relativity experiments – electron deflection in approximate agreement with Lorentz-Einstein prediction.
- Kennedy–Thorndike experiment – time dilation in accordance with Lorentz transformations
- Rossi-Hall experiment Performed in 1940 at Echo Lake and Denver in Colorado, the Rossi-Hall experiment measured the relativistic decay of mesotrons and found it to be in good agreement with the predictions of special relativity. A value for the muon lifetime was given as To=2.3 +/- .2 microseconds, which was later refined in 1943 by Rossi and Nereson to To=2.15 +/-.07 – relativistic effects on a fast-moving particle's half-life
- Experiments to test emitter theory Emission theory was a competing theory for the special theory of relativity, explaining the results of the Michelson-Morley experiment. Emission theories obey the principle of relativity by having no preferred frame for light transmission, but say that light is emitted at speed "c" relative to its source instead of applying the demonstrated that the speed of light is independent of the speed of the emitter.
- Hammar experiment In 1903 the Trouton-Noble experiment, and later the Trouton-Rankine experiment in 1908, presented controversial evidence against the theory of a medium for light propagation known as the Luminiferous aether; a theory that had been an established part of science for nearly one hundred years at the time. These experiments were inspired by the – no "aether flow obstruction"
In addition, particle accelerators routinely accelerate and measure the properties of particles moving at near the speed of light, where their behavior is completely consistent with relativity theory and inconsistent with the earlier Newtonian mechanics In the fields of physics, classical mechanics is one of the two major sub-fields of study in the science of mechanics, which is concerned with the set of physical laws governing and mathematically describing the motions of bodies and aggregates of bodies geometrically distributed within a certain boundary under the action of a system of forces. These machines would simply not work if they were not engineered according to relativistic principles.
<<Table of Contents Special relativity (also known as the special theory of relativity or STR) is the physical theory of measurement in inertial frames of reference proposed in 1905 by Albert Einstein (after the considerable and independent contributions of Hendrik Lorentz, Henri Poincaré and others) in the paper "On the Electrodynamics of Moving Bodies" | Next>> | Show All>>
