Planck length in the context of "Reduced Planck constant"

Play Trivia Questions online!

 or

Skip to study material about Planck length in the context of "Reduced Planck constant"
Ad spacer

⭐ Core Definition: Planck length

In particle physics and physical cosmology, Planck units are a system of units of measurement defined exclusively in terms of four universal physical constants: c, G, ħ, and kB (described further below). Expressing one of these physical constants in terms of Planck units yields a numerical value of 1. They are a system of natural units, defined using fundamental properties of nature (specifically, properties of free space) rather than properties of a chosen prototype object. Originally proposed in 1899 by German physicist Max Planck, they are relevant in research on unified theories such as quantum gravity.

The term Planck scale refers to quantities of space, time, energy and other units that are similar in magnitude to corresponding Planck units. This region may be characterized by particle energies of around 10 GeV or 10 J, time intervals of around 10 s and lengths of around 10 m (approximately the energy-equivalent of the Planck mass, the Planck time and the Planck length, respectively). At the Planck scale, the predictions of the Standard Model, quantum field theory and general relativity are not expected to apply, and quantum effects of gravity are expected to dominate. One example is represented by the conditions in the first 10 seconds of our universe after the Big Bang, approximately 13.8 billion years ago.

↓ Menu

>>>PUT SHARE BUTTONS HERE<<<
In this Dossier

Planck length in the context of Quantum gravity

Quantum gravity (QG) is a field of theoretical physics that seeks unification of the theory of gravity with the principles of quantum mechanics. It deals with environments in which neither gravitational nor quantum effects can be ignored, such as in the vicinity of black holes or similar compact astrophysical objects, as well as in the early stages of the universe moments after the Big Bang.

Three of the four fundamental forces of nature are described within the framework of quantum mechanics and quantum field theory: the electromagnetic interaction, the strong force, and the weak force; this leaves gravity as the only interaction that has not been fully accommodated. The current understanding of gravity is based on Albert Einstein's general theory of relativity, which incorporates his theory of special relativity and deeply modifies the understanding of concepts like time and space. Although general relativity is highly regarded for its elegance and accuracy, it has limitations: the gravitational singularities inside black holes, the ad hoc postulation of dark matter, as well as dark energy and its relation to the cosmological constant are among the current unsolved mysteries regarding gravity, all of which signal the collapse of the general theory of relativity at different scales and highlight the need for a gravitational theory that goes into the quantum realm. At distances close to the Planck length, like those near the center of a black hole, quantum fluctuations of spacetime are expected to play an important role. Finally, the discrepancies between the predicted value for the vacuum energy and the observed values (which, depending on considerations, can be of 60 or 120 orders of magnitude) highlight the necessity for a quantum theory of gravity.

↑ Return to Menu
LINKED FROM (PARENTS)
← Quantum gravity ← Quantum Gravity
LINKS TO (CHILDREN)
Particle physics → Physical cosmology → System of units of measurement → Physical constant → Speed of light → Gravitational constant → Reduced Planck constant → Boltzmann constant → 1 (number) → Natural units → Nature → Vacuum → Prototype (metrology) → Max Planck → Quantum gravity → Energy → Time → Length → Standard Model → Quantum field theory → General relativity → Quantum Gravity → Chronology of the universe → Big Bang →