Planck time
In physics, the Planck time (tP) is the unit of time in the system of natural units known as Planck units. It is the time required for light to travel, in a vacuum, a distance of 1 Planck length, approximately 5.39 × 10−44 s. The unit is named after Max Planck, who was the first to propose it.
The Planck time is defined as:
where:
The two digits between parentheses denote the standard error of the estimated value.
The Planck time is the unique combination of the gravitational constant G, the special-relativistic constant c, and the quantum constant ħ, to produce a constant with units of time. Because the Planck time comes from dimensional analysis, which ignores constant factors, there is no reason to believe that exactly one unit of Planck time has any special physical significance. Rather, the Planck time represents a rough time scale at which quantum gravitational effects are likely to become important. The nature of those effects, and the exact time scale at which they would occur, would need to be derived from an actual theory of quantum gravity.
The reciprocal of the Planck time, which is Planck frequency, can be interpreted as an upper bound on the frequency of a wave. This follows from the interpretation of the Planck length as a minimal length, and hence a lower bound on the wavelength.
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