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  2. Equation of time - Wikipedia

    en.wikipedia.org/wiki/Equation_of_time

    The equation of time was used historically to set clocks. Between the invention of accurate clocks in 1656 and the advent of commercial time distribution services around 1900, there were several common land-based ways to set clocks. A sundial was read and corrected with the table or graph of the equation of time.

  3. Comoving and proper distances - Wikipedia

    en.wikipedia.org/wiki/Comoving_and_proper_distances

    The comoving distance from an observer to a distant object (e.g. galaxy) can be computed by the following formula (derived using the Friedmann–Lemaître–Robertson–Walker metric): = ′ (′) where a(t′) is the scale factor, t e is the time of emission of the photons detected by the observer, t is the present time, and c is the speed of ...

  4. Equations of motion - Wikipedia

    en.wikipedia.org/wiki/Equations_of_motion

    Equation [3] involves the average velocity ⁠ v + v 0 / 2 ⁠. Intuitively, the velocity increases linearly, so the average velocity multiplied by time is the distance traveled while increasing the velocity from v 0 to v, as can be illustrated graphically by plotting velocity against time as a straight line graph. Algebraically, it follows ...

  5. Time in physics - Wikipedia

    en.wikipedia.org/wiki/Time_in_physics

    In the International System of Units (SI), the unit of time is the second (symbol: s). It has been defined since 1967 as "the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom", and is an SI base unit. [12]

  6. Retarded time - Wikipedia

    en.wikipedia.org/wiki/Retarded_time

    Position vectors r and r′ used in the calculation. Retarded time t r or t′ is calculated with a "speed-distance-time" calculation for EM fields.. If the EM field is radiated at position vector r′ (within the source charge distribution), and an observer at position r measures the EM field at time t, the time delay for the field to travel from the charge distribution to the observer is |r ...

  7. Proper time - Wikipedia

    en.wikipedia.org/wiki/Proper_time

    In relativity, proper time (from Latin, meaning own time) along a timelike world 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 . [ 1 ]

  8. Time Warp Edit Distance - Wikipedia

    en.wikipedia.org/wiki/Time_Warp_Edit_Distance

    In the data analysis of time series, Time Warp Edit Distance (TWED) is a measure of similarity (or dissimilarity) between pairs of discrete time series, controlling the relative distortion of the time units of the two series using the physical notion of elasticity.

  9. Stokes number - Wikipedia

    en.wikipedia.org/wiki/Stokes_number

    To convert the velocity as a function of time to a particle velocity distribution as a function of distance, let's assume a 1-dimensional velocity jump in the direction. Let's assume x = 0 {\displaystyle x=0} is positioned where the shock wave is, and then integrate the previous equation to get: