# Planck time

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## Planck time

A time equal to 5.4 × 10–44 second, and defined as √(hG /2πc 5); h is the Planck constant, G the gravitational constant, and c the speed of light. The uncertainty principle of quantum mechanics prevents any speculation on times shorter than the Planck time after the Big Bang.
Collins Dictionary of Astronomy © Market House Books Ltd, 2006

## Planck time

[′pläŋk ‚tīm]
(physics)
The constant (Gh /2π c 5)1/2with dimensions of “time” formed from Planck's constant h, the gravitational constant G, and the speed of light c ; approximately 10-43 second.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
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that are employed throughout the following text, where [t.sub.*] (= [r.sub.*]/c) is the Planck time [4, p.
The smallest possible unit of time measurement is about 10^-43 seconds, which is called Planck time. (One unit of Planck time is the time it takes for light to travel 10^-35 meters, which is about 10^20 times smaller than an atomic nucleus.) Let us imagine a ruler divided into Planck units, and we lay this ruler along a series of events that occurred over a period of 50 years.
If we want to study the universe from 10-33 to the limit of know-ability i.e., up to the Planck Time (5.5x10-44 seconds), we need to unify all four fundamental forces into one mathematical model.
OUR MINDS ONLY EXIST IN THE INSTANT OF PLANCK time, roughly [10.sup.-25] of a second.
a long time compared to the femtosecond, the attosecond and the shortest possible unit of time - known as Planck time.
In other words, it turns out to be permissible to assume that quanta of space having the size of Planck length [l.sub.p] = [square root of [??]G/[c.sup.3]] are the fundamental constituents of space (namely that it is not possible to observe areas or volumes smaller than Planck scale) and that Planck time [t.sub.p] = [square root of [??]G/[c.sup.5]] is the least unit of motion (namely that it is not possible to observe numerical order of movements smaller than Planck time).
Looking far enough back, one finds not an edge, but Planck Time, that moment in the early expansion of the universe beyond which current theoretical physics can no longer provide any explanations.
In the final chapters he explores Planck Time and the ultimate fate of the universe.
This is the Planck time, the time it takes light to cross the Planck length.
"Planck length", "Planck time", "Planck mass", and "Planck temperature"' [10, p.
The Planck time is also calculated from the gravitational constant, the speed of light and Planck's constant in such a way that moving at one Planck length per one Planck time would be equal to the speed of light.
The invariability of Planck constant is a consequence of the fact that, although individually Planck energy and Planck time change in time, their product remains constant:

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