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Theory of relativity

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Albert Einstein's theory of relativity is a set of two theories in physics: special relativity and general relativity. The core idea of both theories is that two observers who move relative to each other will often measure different 'time' and 'space' intervals for the same events, but the content of physical law will be the same for both.

Special relativity, developed in 1905, only considers observers in inertial reference frames which are in uniform motion with respect to each other. Einstein's paper that year was called "On the Electrodynamics of Moving Bodies". While developing this theory, Einstein wrote to Mileva (his wife) about "our work on relative motion". This paper introduced the special theory of relativity, a theory of time, distance, mass and energy. The theory postulates that the speed of light in vacuum will be the same for these observers.

One of the strengths of special relativity is that it can be derived from only a few premises:

  • The speed of light in vacuum is a constant.
  • The laws of physics are the same for all observers in inertial frames.
  • Causality holds; that is, causes always precede their effects.

Special relativity thus makes a general principle with applications in physics, chemistry, and even life sciences. It not only depicts relationships between the perspectives taken from loose moving bodies. Often together with quantum mechanics, special relativity is also employed to describe microphysical motions inside lumps of condensed matter, like pebbles and biological organs such as kidneys or brain. It, e. g., was of help to electroneurobiology researchers trying to explain physiological mechanisms that enact variations of attention, and disconnection states such as sleep and coma, as electric field-mediated relativistic effects in brain biophysics.

Alberts Quote 'to be or not to be that is the question. what fucker would have said that shit please tell me Hitler would you say shit like that no i guess not'

General relativity was published by Einstein in 1916 (submitted as a series of lectures before the Prussian Academy of Sciences November 25 1915). However, it must be noted that German mathematician David Hilbert wrote and made public the covariant equations before Einstein. This resulted in not a few accusations of plagiarism against Einstein, but it is probably closer to reality that they both were co-creators of general relativity. The theory gave an introduction of an equation that replaced Newton's law of gravity. It uses the mathematics of differential geometry and tensors in order to describe gravity.

This theory considered all observers to be equivalent, not only those moving at a uniform speed. The laws of general relativity are the same for all observers, even if they are accelerated with respect to each other. In general relativity, gravity is no longer a force (as it was in Newton's law of gravity) but is a consequence of the curvature of space-time. General relativity is a geometrical theory which postulates that the presence of mass and energy "curves" spacetime, and this curvature affects the path of free particles (and even the path of light).


For more information see the respective articles on special relativity and general relativity.

See also

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