Physics

physics (Greek φυσική, physike „the natural one “) is the natural science, which examines the fundamental laws of nature, its elementary components and their reciprocal effects. It is concerned both with the characteristics and the behavior of subject and Fields in space and time and with the structure of space and time.

Physics describes nature quantitatively by means of scientific models, so-called theories, and makes thereby in particular forecasts possible over the behavior of the regarded systems.In addition physics uses the language of mathematics.

In connection with physics the question about the ethics of scientific research was raised also for the first time, a topic, also in the literature, approximately in the play the physicists of Friedrich Duerrenmatt, taken up is.

Table of contents

the theory building of modern physics

the theory building of physics rests on two columns, relativity theory and quantum physics. BothTheories contain its predecessor, Newton's physics, over the correspondence principle in such a way specified as border line and have therefore a larger range of validity than these.

relativity theory

relativity theory leads a completely new understanding of the phenomena space and time. It was coined/shaped mainly by Albert Einstein. Afterwards it does not concern universally valid order structures, but spatial and temporal distances are differently judged by different observers. Space and time merge thereby into a four-dimensional space-time. Those Gravitation is attributed to a curvature of this space-time, those by the presence of mass and/or. Energy is caused. In relativity theory the cosmology becomes also for the first time a scientific topic. The formulation of relativity theory is considered to that as the beginning modern physics, even if it is called frequently completion of classical physics.

quantum physics

quantum physics describes the laws of nature within the atomic and subatomic range and breaks still more radically with classical conceptions than relativity theory. Manyphysical dimension prove in certain situations as quantized, i.e. they take always only certain discrete values and change in the form of quantum transitions. Subject proves as phenomenon, only in portions, to the so-called elementary particles or , into action goes to quanta. Their place of residence is permitted no longer by a course in the area describes to separate by waves, over which a probability for it can be indicated, the particle with a measurement in a certain spacefind. One speaks of a wave particle dualism. The place of residence of a particle between two such measurements is not unknown only, but does not define even. Most physicists conclude from the fact that in the long run the conception of the existence of a reality independent of the observerto be given up must. Regarding the characteristics of these particles symmetry characteristics play a central role.

The laws of quantum physics extract themselves from the human opinion to a large extent, and over their interpretation also today still no consent ( interpretations of quantum physics) prevails. Neverthelessit counts regarding its empirical success to at the best secured knowledge mankind at all.

the four basic forces

modern physics knows the following four basic forces:

One of the goals of physics is it to describe all basic forces in a standardized total concept. So far is it however onlysucceeded to represent the electromagnetic reciprocal effect as combination of the electrical and the magnetic reciprocal effect and to combine likewise the electromagnetic reciprocal effect and the weak reciprocal effect to a so-called electricalweak reciprocal effect. The combination electricalweak and strong reciprocal effect became the theory that Supersymmetry devised, whose validity is however disputed. The largest difficulties arise within the range of the gravitation strength, since over them - admits even if for a long time - nevertheless only little secured knowledge is present. Relevant problem here is their hardly measurable influenceon all systems in the laboratory yardstick.

To these fundamental reciprocal effects still another fundamental principle of quantum physics, the Pauli-Prinzip comes. From this principle a further reciprocal effect is indirectly derived, the exchange reciprocal effect.

present one borders of the physical realization

The goal of today's physics is it to describe and attribute to the reciprocal effect of fewer elementary particles all procedures of nature by as small a number from as simple a laws of nature as possible to. To what extent this goal is in principle or practically attainable, is completely open.

The range of validity of the well-known physical laws is extremely extensive nevertheless.Unsettled phenomena of physics can be assigned two in principle different groups:

  • Phenomena, whose underlying laws are still unknown. In addition rank in particular phenomena of particle physics and such, among their description those general relativity theory and quantum physics at the same time necessarily are, as for example the Big Bang. The reason for this is that did not succeed so far to formulate a Quantenfeldtheorie closed in itself which quantum physics and relativity theory combines completely.
  • Phenomena, thosewell-known laws obey, whose description fails however because of the mathematical complexity. For such situations one tries to develop calculable approximation models, whose quality and range of validity can be determined often only experimentally.

One of the most important unresolved problems in this connection are that of human consciousness. In particular the question, among which the two groups of problems it is to be ranked, is controversially discussed.

Physics is not in principle able to actually meet statements about the nature of the things. It limitsitself to fathom the regularities the things are subjected to which.

Why nature obeys at all certain laws, is in the long run unknown. A partial answer gives only the anthropische principle, by stating that it in a cosmos without laws of naturenobody would give, which could be surprised at their absence.

ranges of topics of physics

in the following are represented the different ranges of topics of physics with short comment arranged according to superordinate, theoretical framework and sorted at the same time to a large extent chronologically. Manythe specified topics cannot be assigned clearly a theory. Like that for example many phenomena of thermodynamics are only on basis of the quantum and relativity theory explainable. In these cases the topic under the oldest theory is arranged and existing relevant purchasesto recent theories are suggested with (blank) for the relativity and (QT) for the quantum theory. The list contains both phenomenon-oriented subjects and cross section theories (QST) with area-spreading range of application. See also the physics portal with unkommentierten, but according to differently criteria topic lists sortedas well as the alphabetical topic list physics.

Newton's physics including electrodynamics

… is the range of the physics, to which up to the formulation admits of relativity theory was.

relativity theory

… is concerned with the structure of space and time as well as with the nature of the gravitation. The unit from Newton's physics, electrodynamics and relativity theory becomesclassical physics calls.

  • Special relativity theory describes the behavior of space, time and masses from the view of observers, who move relatively to each other. Primarily constant speeds are regarded (QST).
  • General relativity theory develops on the specialand the phenomenon of the gravitation attributes to a curvature of space and time.

quantum physics

… is necessary for the description of phenomena in the Mikrokosmos, where the laws of the classical mechanics arrive at its border. During itexperimentally again and again outstanding confirmed and the entire modern technology is based on it, until today about its correct interpretation argues. In the following in particular topics of nonrelativistic quantum mechanics are not specified, with those itself the number of the particles involvedchanges.

relativistic quantum physics

… is concerned with phenomena, for whose description quantum physics and relativity theory are necessary at the same time.

interdisciplinary one and technically oriented ranges of topics

  • astrophysicsapplies physical methods to the study of astronomical phenomena.
  • With physical chemistry it concerns the frontier between physics and chemistry. Physical chemists apply the methodology of physics to the opinion objects of chemistry.
  • Technical physics is that subsection of physics, which is concerned with technical applications of physical knowledge.
  • In biophysics the physical regularities, to which organisms and its reciprocal effect with nature are subject, are examined.
  • Geophysics use physical models for the explanation of geological structures andProcedures.
  • Quantum electronics is a relatively recent Forschungsgebiet and applies the results of the quantum theory to the development of electronic circuits.
  • In the theory of the quantum computers physics steps into interdisciplinary co-operation with computer science. Here among other things algorithms become alsosmaller complexity than possible with classical computers.
  • Accelerator physics concerns itself with the development of particle accelerators. These are needed, in order to reach the power densities of elementary particle physics, in addition, as radiation source for investigations within a wider scientific range.
  • The reactor physics employsitself with the technical control of nuclear reactions in nuclear reactors.
  • Environmental physics concerns itself in its research particularly with the ranges energy and climate.
  • Soziophysik and restaurant economics apply physical and statistic methods to social, economic, cultural and political phenomena.

methodology of physics

the process of the realization production in physics runs in close teeth of experiment and theory, consists thus of empirical data gathering and - evaluation and at the same time providing theoretical models to its explanation. Nevertheless have themselvesin the process 20. Century specializations developed, which coin/shape in particular professionally operated physics today. Therefore roughly experimental physics can theoretical physics be differentiated and from each other.

experimental physics

during some natural sciences as for instance the astronomy and the meteorology itselfmethodically to a large extent to the observations of their investigation article to limit must, stands in physics the experiment in the foreground. Experimental physics tries by draft, structure, to seek out and to describe by means of empirical models execution and evaluation of experiments regularities in nature.To enter it tried on the one hand physical new ground, on the other hand one it examines made forecasts from theoretical physics.

Basis of a physical experiment is it, the characteristics of a physical system, for example a particle accelerator, prepared before, a vacuum chamber with detectors or a thrownTo express stone by measurement in number form, approximately as length of one particle-purely, pulse amplitude of an electrical tension pulse or as barrier impact speed.

Concrete way either only the time-independent (static) characteristics of an object are measured or one examine the temporal development (dynamics)the system, approximately in which one and final values of a measured variable before and at the expiration of a procedure determine initial values or determine alternatively continuous intermediate values.

theoretical physics

the task of theoretical physics again consists of it, the empirical modelsto attribute experimental physics mathematically to well-known basic theories or, if this is not possible to describe by as small a number of basic assumptions as possible (hypotheses). It derives further from already well-known models empirically examinable forecasts.

With the development oneModel in principle the reality is idealized; one concentrates first only on a simplified picture, in order to grasp and investigate its aspects; after the model for these conditions developed, it is continued to generalize.

To the theoretical description of a physicalSystem uses one the language of mathematics. Its components are represented in addition by mathematical objects like for example scalars or vectors, which stand to each other in relations specified by equations. The purpose of the model is it, from well-known sizes of unknownto calculate and to predict thus for example the result of an experimental measurement.

Phenomena of the world, cannot which be described mathematically, as for example human consciousness, are regarded generally not as the subject of physics.

The fundamental measure for thoseQuality of a theory is, as also in many natural sciences, the agreement with reproducible experiments. By the comparison with the experiment the range of validity and the accuracy of a theory can be determined, however it can be never proven „“. Around a theoryto disprove, and/or. in order to demonstrate the borders of their range of validity, in principle only one experiment is sufficient, if it is reproducible.

Experimental physics and theoretical physics stand thus in constant interrelation to each other. It can occur however that results discipline thatprecede others: Like that at present many forecasts of the stringer theory are not experimentally examinable; on the other hand many partial extremely exactly measured values from the area of particle physics are at the today's time at the beginning 21. Century by the associated theory, quantum chromodynamics,not calculably.

mathematical physics and applied physics

in addition to this fundamental division of physics one differentiates between sometimes still two further Unterdisziplinen, mathematical physics and applied physics. First becomes occasionally as subsection of theoretical physicsregarded, it differs from this however in the fact that their study object not concrete physical phenomena are, but the results of theoretical physics. It abstracts thereby from jedweder application and is interested instead for the mathematical characteristics of a model, in particular itsmore deeply lying symmetries and invariances. In this way it develops Verallgemeinerungen and variants of already well-known theories, which can find then again as working material of the theoretical physicists in the modelling of empirical procedures employment.

Applied physics stands against it in (indistinct)Demarcation to experimental physics, partly also to theoretical physics. Their substantial characteristic is that it investigates a given physical phenomenon not around its sake, but around the realizations come out from the investigation for the solution (usually) of a non-physical problemto begin. Their applications are appropriate for z. B. in the area of the technology or electronics, in medicine, chemistry or astronomy, in addition, in the economic science, where z. B. in the risk management methods of theoretical solid-state physics to the employment come.

simulation/computer physics

with the progressive development of the computing systems has itself in the last decades 20. Century and accelerated since approximately 1990 the computer simulation as new methodology within physics develops. Computer physicists are not pure theoreticians, there them throughtheir Simulationen theories to test tries, in addition, no pure experimenters, since their experiments take place exclusively in the world of the computer. The range of possible Simulationen covers the complete span of mathematical physics over Simulationen of cosmological models up toapplied physics off. Naturally this field of physics has numerous connecting factors to computer science.

relationship to other sciences

demarcation to other sciences

to the demarcation in relation to biology becomes physics often than thoseScience of dead nature marks.

A demarcation in relation to chemistry is not so clear; the transition of the physics of the electron sheath, thus the atomic and molecule physics, to the Quantenchemie is flowing.

Mathematics describes contrary to physicsno material objects, but abstract terms and their characteristics.

reciprocal effect with other sciences

physics is considered than the fundamental natural science, on the all different one as for example the astronomy, chemistry, geology and in the long run alsobiology develop. Physical principles and models apply their also in disciplines beyond the natural sciences, particularly within the technical range, like in the engineering sciences, in addition, in the quantitative economic science. Turned around also often realizations from other fields of activityas mathematics or the astronomy enriches and stimulates the physical research.

Also in philosophy the realizations of physics attention find: Thus the philosophical branch of the Metaphysik explanations for the nature of nature tries to find, during itself thosePhysics on its description limits.


history

the modern history of physics is rooted in antique pre-working above all Greek scholar (in particular of Aristoteles) and begins approximately starting from the year 1500. Since this time one can ofphysics as independent science speak, although there were physical discoveries and teachings already before, for example about the fire, the wheel, the Hebelgesetz and its application in simple machines, formulated of Archimedes, first realizations in that Optics, the liquid teachings and conceptions of the structure of the bodies (Demokrit particle model).

see also: Portal: Physics, list of physical sets

of literature

  • Károly Simonyi: “Culture history of physics”. Leipzig,Jena, Berlin: Urania publishing house, 1990
  • Landau, Lifschitz: “Theoretical physics” in 8 volumes, academy publishing house Berlin, again: Harri German publishing house Frankfurt/Main.
  • Paul A. Tipler, genes Mosca: Physics for scientists and engineers. 2. Edition. Spectrum academic publishing house, 2004, ISBN 3-827-41164-5
  • smelling pool of broadcasting corporations Feynman, RobertLeighton, Matthew of sand:Lectures on physics. Oldenbourg 1999, ISBN 3-486-25857-5
  • CH. Gerthsen, D. Meschede: Gerthsen physics. 22. Edition. Springer publishing house, 2004, ISBN 3-540-02622-3
  • W. Demtröder: Experimental physics. 3. Edition. Springer, 2004, ISBN 3-540-26034-X
  • Ludwig miner, Clemens shepherd, Thomas's village Mueller,William T. Herring, Klaus bull city:Text book of experimental physics. 10. Edition. de Gruyter, 1998, ISBN 3-110-12870-5

see also

applied physics, astrophysics, experimental physics, geophysics, mathematical physics, theoretical physics

mathematics, chemistry, Physical chemistry, biophysics

physics study, physics at school

Web on the left of

Wiktionary: Physics - word origin, synonyms and translations
Wikibooks: Free books to physical topics - learning and teaching materials
Wikiquote: Physics - quotations
 

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