Planck length

The Planck length (ℓp) is the distance or length scale below which is expected to have a space stop geometry classic. A lower measurement predictably cannot be adequately addressed in current physics models due to the appearance of quantum gravity effects .

It is reasonable to suspect that the reconciliation theory of general relativity and quantum theory involve the three constants of c, G, and Ћ. Planck noted that apart from numerical factors there is a unique way to use these constants to define units of length , time, and mass .

Planck’s length is part of the natural system of units, and is calculated from three fundamental constants, the speed of light , Planck’s constant, and the gravitational constant. Equivalent to the distance a photon travels, traveling at the speed of light, in Planck’s time.


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  • 1 Definition
  • 2 Quantum structure of space
  • 3 See also
  • 4 External links
  • 5 Sources


This Planck length value is defined as the Compton wavelength of the Planck mass particle:


Note: The two digits in parentheses denote the uncertainty in the last digits of the value.

where c is the speed of light in a vacuum , G is the universal gravitational constant, and Ћ is the reduced Planck constant.

Planck constant value

Value is very small about 1.6 * 10 -35 meters. Physicists have long suspected that quantum gravity will be important to understanding physics at around this scale. The reason is very simple: any calculation that predicts a length using only the constants c, G, and Ћ must give Planck’s length, in your case, multiplied by a minor numerical factor such as 2 π.

Quantum structure of space

In the field of classical physics, which ranges from Newtonian mechanics to the theory of general relativity, space is considered to be infinitely divisible and seen locally under the microscope as Euclidean space.

In 1900 Planck formulated that energy is radiated into separate small units called quanta. Moving forward in the development of this theory, he discovered a constant of a universal nature known as the Planck constant. Planck’s law states that the energy of each quantum is equal to the frequency of radiation multiplied by the universal constant. Planck’s discoveries, which were later verified by other scientists, promoted the birth of an entirely new field of physics, known as quantum mechanics.

Analyzing length scales as incredibly small as Planck’s length, the classical conception of space as a locally Euclidean continuum is expected to be invalid, and at those scales space does in fact have some kind of quantum probabilistic behavior. Another situation in which quantum effects are expected to be important is when the Ricci scalar curvature is of the order of the inverse of the square of the Planck length:

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The predictable quantum effects when the curvature is close to that value will have to be dealt with by some kind of quantum theory of gravitation


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