Instruct: Given a question, retrieve passages that answer the question.
Query: Who discovered special relativity?
Notable German physicists before the 20th century include Hermann von Helmholtz, Joseph von Fraunhofer and Gabriel Daniel Fahrenheit, among others. Albert Einstein introduced the special relativity and general relativity theories for light and gravity in 1905 and 1915 respectively. Along with Max Planck, he was instrumental in the introduction of quantum mechanics, in which Werner Heisenberg and Max Born later made major contributions. Wilhelm Röntgen discovered X-rays. Otto Hahn was a pioneer in the fields of radiochemistry and discovered nuclear fission, while Ferdinand Cohn and Robert Koch were founders of microbiology. Numerous mathematicians were born in Germany, including Carl Friedrich Gauss, David Hilbert, Bernhard Riemann, Gottfried Leibniz, Karl Weierstrass, Hermann Weyl, Felix Klein and Emmy Noether.
The first discovery of electromagnetic radiation other than visible light came in 1800, when William Herschel discovered infrared radiation. He was studying the temperature of different colors by moving a thermometer through light split by a prism. He noticed that the highest temperature was beyond red. He theorized that this temperature change was due to "calorific rays" that were a type of light ray that could not be seen.
Faster-than-light communication is, according to relativity, equivalent to time travel. What we measure as the speed of light in a vacuum (or near vacuum) is actually the fundamental physical constant "c". This means that all inertial observers, regardless of their relative velocity, will always measure zero-mass particles such as photons traveling at "c" in a vacuum. This result means that measurements of time and velocity in different frames are no longer related simply by constant shifts, but are instead related by Poincaré transformations. These transformations have important implications:
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Academics working at the university include Sir Tim Berners-Lee, inventor of the World Wide Web, Wendy Hall, inventor of Microcosm (hypermedia system) a predecessor of the World Wide Web, founding director of the Web Science Trust between the University of Southampton and MIT, José Antonio Bowen, President of Goucher College and a Fellow of the Royal Society of Arts, Erich Zepler, who made leading contributions to radio receiver development, David Payne, who invented EDFA for use in fibre optics cables, Sir Barry Cunliffe, a pioneer of modern British archaeology, Ray Monk, the biographer of Ludwig Wittgenstein, Albie Sachs, former Judge of the Constitutional Court of South Africa, and Tim Holt, former President of the Royal Statistical Society and Office for National Statistics.
James Clerk Maxwell began working on Michael Faraday's lines of force. In his 1861 paper "" he modelled these magnetic lines of force using a sea of molecular vortices that he considered to be partly made of aether and partly made of ordinary matter. He derived expressions for the dielectric constant and the magnetic permeability in terms of the transverse elasticity and the density of this elastic medium. He then equated the ratio of the dielectric constant to the magnetic permeability with a suitably adapted version of Weber and Kohlrausch's result of 1856, and he substituted this result into Newton's equation for the speed of sound. On obtaining a value that was close to the speed of light as measured by Hippolyte Fizeau, Maxwell concluded that light consists in undulations of the same medium that is the cause of electric and magnetic phenomena.
In the late 1980s, Berners-Lee, then a scientist at CERN, invented the World Wide Web to meet the demand for simple and immediate information-sharing among physicists working at CERN and different universities or institutes all over the world.
Group D
In 1850, William Rankine first used the phrase "the law of the conservation of energy" for the principle.
Electromagnetic radiation of wavelengths other than visible light were discovered in the early 19th century. The discovery of infrared radiation is ascribed to William Herschel, the astronomer. Herschel published his results in 1800 before the Royal Society of London. Herschel, like Ritter, used a prism to refract light from the Sun and detected the infrared (beyond the red part of the spectrum), through an increase in the temperature recorded by a thermometer.
In 1926, Max Planck wrote an important paper on the basics of thermodynamics. He indicated the principle
Group C
Mass and energy can be seen as two names (and two measurement units) for the same underlying, conserved physical quantity. Thus, the laws of conservation of energy and conservation of (total) mass are equivalent and both hold true. Einstein elaborated in a 1946 essay that "the principle of the conservation of mass [...] proved inadequate in the face of the special theory of relativity. It was therefore merged with the energy conservation principle—just as, about 60 years before, the principle of the conservation of mechanical energy had been combined with the principle of the conservation of heat [thermal energy]. We might say that the principle of the conservation of energy, having previously swallowed up that of the conservation of heat, now proceeded to swallow that of the conservation of mass—and holds the field alone."
Engineers such as John Smeaton, Peter Ewart, , Gustave-Adolphe Hirn and Marc Seguin recognized that conservation of momentum alone was not adequate for practical calculation and made use of Leibniz's principle. The principle was also championed by some chemists such as William Hyde Wollaston. Academics such as John Playfair were quick to point out that kinetic energy is clearly not conserved. This is obvious to a modern analysis based on the second law of thermodynamics, but in the 18th and 19th centuries the fate of the lost energy was still unknown.
Germany has a long heritage of using electromagnetic waves for detecting objects. In 1888, Heinrich Hertz, who first demonstrated the existence of these waves, also noted that they, like light, were reflected by metal surfaces. In 1904, Christian Hülsmeyer obtained German and foreign patents for an apparatus, the "Telemobilskop", using a "spark gap transmitter" that could detect ships and prevent collisions; this is often cited as the first radar, but, without directly providing range, it does not qualify for this classification. With the advent of the radio tube and electronics, other detection-only systems were developed, but all used continuous waves and could not measure distance.
In 1933, physicist Rudolf Kühnhold, Scientific Director at the "Kriegsmarine" (German Navy) "Nachrichtenmittel-Versuchsanstalt" (NVA—Experimental Institute of Communication Systems) in Kiel, initiated experiments in the microwave region to measure the distance to a target. For the transmitter, he obtained assistance from two radio amateur operators, Paul-Günther Erbslöh and Hans-Karl Freiherr von Willisen. In January 1934, they formed at Berlin-Oberschöneweide the company "Gesellschaft für Elektroakustische und Mechanische Apparate" (GEMA) for this work.
Two developments in geometry in the 19th century changed the way it had been studied previously. These were the discovery of non-Euclidean geometries by Nikolai Ivanovich Lobachevsky, János Bolyai and Carl Friedrich Gauss and of the formulation of symmetry as the central consideration in the Erlangen Programme of Felix Klein (which generalized the Euclidean and non-Euclidean geometries). Two of the master geometers of the time were Bernhard Riemann (1826–1866), working primarily with tools from mathematical analysis, and introducing the Riemann surface, and Henri Poincaré, the founder of algebraic topology and the geometric theory of dynamical systems. As a consequence of these major changes in the conception of geometry, the concept of "space" became something rich and varied, and the natural background for theories as different as complex analysis and classical mechanics.
Ray is a one side infinite geodesic which is minimizing on each interval
Electromagnetic radiation of wavelengths other than those of visible light were discovered in the early 19th century. The discovery of infrared radiation is ascribed to astronomer William Herschel, who published his results in 1800 before the Royal Society of London. Herschel used a glass prism to refract light from the Sun and detected invisible rays that caused heating beyond the red part of the spectrum, through an increase in the temperature recorded with a thermometer. These "calorific rays" were later termed infrared.
Johann Carl Friedrich Gauss (; ; ; (30 April 177723 February 1855) was a German mathematician and physicist who made significant contributions to many fields in mathematics and sciences. Sometimes referred to as the "Princeps mathematicorum" () and "the greatest mathematician since antiquity", Gauss had an exceptional influence in many fields of mathematics and science, and is ranked among history's most influential mathematicians.
The relation between electric current, magnetic fields and physical forces was first noted by Hans Christian Ørsted who, in 1820, observed a compass needle was deflected from pointing North when a current flowed in an adjacent wire. The tangent galvanometer was used to measure currents using this effect, where the restoring force returning the pointer to the zero position was provided by the Earth's magnetic field. This made these instruments usable only when aligned with the Earth's field. Sensitivity of the instrument was increased by using additional turns of wire to multiply the effect – the instruments were called "multipliers".
Swiss electrical engineer George de Mestral invented his first touch fastener when, in 1941, he went for a walk in the woods and wondered why Burdock seeds clung to his coat and dog. He discovered it could be turned into something useful. He patented it in 1955 and subsequently refined and developed its practical manufacture until its commercial introduction in the late 1950s.
Ignatowski wrote some papers on special relativity. In 1910 he was to first who tried to derive the Lorentz transformation by group theory only using the relativity principle, and without the postulate of the constancy of the speed of light (1910b, 1911b, 1911c, 1911h). Although he derived the correct transformation, the invariant limiting speed remained undefined. Ignatowski had to resort to length contraction of moving electrostatic fields in order to identify this limiting velocity with the velocity of light in vacuum. While some said that this approach was insufficient and the second postulate is still needed, others continued the attempts to derive special relativity without the light postulate (see Postulates of special relativity). Ignatowski also investigated the status of rigid bodies within special relativity (1910a, 1911a). He concluded that velocities greater than the speed of light are possible, even though he showed that those are not signal velocities and therefore are not in conflict with relativity (1910b, 1911g). He also formulated a relativistic theory of hydrodynamics (1911f).
It was also claimed that special relativity cannot handle acceleration, which would lead to contradictions in some situations. However, this assessment is not correct, since acceleration actually can be described in the framework of special relativity (see Acceleration (special relativity), Proper reference frame (flat spacetime), Hyperbolic motion, Rindler coordinates, Born coordinates). Paradoxes relying on insufficient understanding of these facts were discovered in the early years of relativity. For example, Max Born (1909) tried to combine the concept of rigid bodies with special relativity. That this model was insufficient was shown by Paul Ehrenfest (1909), who demonstrated that a rotating rigid body would, according to Born's definition, undergo a contraction of the circumference without contraction of the radius, which is impossible (Ehrenfest paradox). Max von Laue (1911) showed that rigid bodies cannot exist in special relativity, since the propagation of signals cannot exceed the speed of light, so an accelerating and rotating body will undergo deformations.
First attempts to modify special relativity by introducing an observer-independent length were made by Pavlopoulos (1967), who estimated this length at about .
In the context of quantum gravity, Giovanni Amelino-Camelia (2000) introduced what now is called doubly special relativity, by proposing a specific realization of preserving invariance of the Planck length .
This was reformulated by Kowalski-Glikman (2001) in terms of an observer-independent Planck mass.
A different model, inspired by that of Amelino-Camelia, was proposed in 2001 by João Magueijo and Lee Smolin, who also focused on the invariance of Planck energy.
Planck, in 1909, compared the implications of the modern relativity principle — he particularly referred to the relativity of time – with the revolution by the Copernican system. An important factor in the adoption of special relativity by physicists was its development by Minkowski into a spacetime theory. Consequently, by about 1911, most theoretical physicists accepted special relativity. In 1912 Wilhelm Wien recommended both Lorentz (for the mathematical framework) and Einstein (for reducing it to a simple principle) for the Nobel Prize in Physics – although it was decided by the Nobel committee not to award the prize for special relativity. Only a minority of theoretical physicists such as Abraham, Lorentz, Poincaré, or Langevin still believed in the existence of an aether. Einstein later (1918–1920) qualified his position by arguing that one can speak about a relativistic aether, but the "idea of motion" cannot be applied to it. Lorentz and Poincaré had always argued that motion through the aether was undetectable. Einstein used the expression "special theory of relativity" in 1915, to distinguish it from general relativity.