Proper timeIn relativity, proper time along a timelikeworld line is defined as the time as measured by a clock following that line. The proper time interval between two events on a world line is the change in proper time, which is independent of coordinates, and is a Lorentz scalar. The interval is the quantity of interest, since proper time itself is fixed only up to an arbitrary additive constant, namely the setting of the clock at some event along the world line.
Observer (special relativity)In special relativity, an observer is a frame of reference from which a set of objects or events are being measured. Usually this is an inertial observer or inertial reference frame. When the frame is attached to an object it is said to be a comoving frame. Less often an observer may be an arbitrary non-inertial reference frame such as a Rindler frame which may be called an accelerating observer.
Special relativityTheory of interwoven space and time by Albert EinsteinAlbert Einstein around 1905, the year his paper on special relativity was publishedIn physics, the special theory of relativity, or simply special relativity, is a scientific theory of the relationship between space and time.
SpacetimeIn physics, spacetime, or the space-time continuum, is a mathematical model that fuses the three dimensions of space and the one dimension of time into a single four-dimensional continuum. Spacetime diagrams are useful in visualizing and understanding relativistic effects, such as how different observers perceive where and when events occur.
Event (relativity)Situation or occurrence located at a specific point in space and time An event in spacetime and a 2D slice of its causal cone.Time dilationTime dilation is the difference in elapsed time as measured by two clocks, either because of a relative velocity, a consequence of special relativity, or a difference in gravitational potential between their locations due to gravitational time dilation. When unspecified, "time dilation" usually refers to the effect due to velocity.
Coordinate systemIn geometry, a coordinate system is a system that uses one or more numbers, or coordinates, to uniquely determine and standardize the position of the points or other geometric elements on a manifold such as Euclidean space. The coordinates are not interchangeable; they are commonly distinguished by their position in an ordered tuple, or by a label, such as in "the x-coordinate".
Einstein synchronisationEinstein synchronisation (or Poincaré–Einstein synchronisation) is a convention for synchronising clocks at different places by means of signal exchanges. This synchronisation method was used by telegraphers in the middle 19th century, but was popularized by Henri Poincaré and Albert Einstein, who applied it to light signals and recognized its fundamental role in relativity theory. Its principal value is for clocks within a single inertial frame.
Theory of relativityThe theory of relativity comprises two physics theories by Albert Einstein: special relativity and general relativity, proposed and published in 1905 and 1915, respectively. Special relativity applies to all physical phenomena in the absence of gravity. General relativity explains the law of gravitation and its relation to the forces of nature. It applies to the cosmological and astrophysical realm, including astronomy.
TimeContinuous progression from past to futureNot to be confused with Thyme.Time is the continuous progression of existence that occurs in an apparently irreversible succession from the past, through the present, and into the future.
Three-dimensional spaceGeometric model of the physical spaceA representation of a three-dimensional Cartesian coordinate systemIn geometry, a three-dimensional space (3D space) is a mathematical space in which three values (termed coordinates) are required to determine the position of a point. Alternatively, it can be referred to as 3-space. Most commonly, it means the three-dimensional Euclidean space, which is the Euclidean space of dimension three, which models physical space.
Inertial frame of referenceIn classical physics and special relativity, an inertial frame of reference (also called an inertial space or a Galilean reference frame) is a frame of reference in which objects exhibit inertia: they remain at rest or in uniform motion relative to the frame until acted upon by external forces. In such a frame, the laws of nature can be observed without the need to correct for acceleration.*As an Amazon Associate I earn from qualifying purchases.