In particle physics and physical cosmology, the Planck scale is an energy scale around 1. Particle physics is a branch of Physics that studies the elementary constituents of Matter and Radiation, and the interactions between them Physical cosmology, as a branch of Astronomy, is the study of the large-scale structure of the Universe and is concerned with fundamental questions about its In Physics, length scale is a particular Length or Distance determined with the precision of one order (or a few orders of magnitude 22 × 10²⁸ eV (which corresponds by the mass–energy equivalence to the Planck mass 2. In Physics, mass–energy equivalence is the concept that for particles slower than light any Mass has an associated Energy and vice versa. The Planck mass is the unit of Mass, denoted by m P in the system of Natural units known as Planck units. 17645 × 10⁻⁸ kg) at which quantum effects of gravity become strong. Quantum mechanics is the study of mechanical systems whose dimensions are close to the Atomic scale such as Molecules Atoms Electrons Gravitation is a natural Phenomenon by which objects with Mass attract one another At this scale, the description of sub-atomic particle interactions in terms of quantum field theory breaks down (due to the non-renormalizability of gravity). In quantum field theory (QFT the forces between particles are mediated by other particles In Quantum field theory, the Statistical mechanics of fields and the theory of self-similar geometric structures renormalization refers to a collection That is; although physicists have a fairly good understanding of the other fundamental interactions or forces on the quantum level, gravity is problematic, and cannot be integrated with quantum mechanics (at high energies) using the usual framework of quantum field theory. In Physics, a fundamental interaction or fundamental force is a mechanism by which particles interact with each other and which cannot be explained in terms Gravitation is a natural Phenomenon by which objects with Mass attract one another Quantum mechanics is the study of mechanical systems whose dimensions are close to the Atomic scale such as Molecules Atoms Electrons For energies approaching the Planck scale, an exact theory of quantum gravity is required, and the current leading candidate is string theory, or its modernized form M-theory. Quantum gravity is the field of Theoretical physics attempting to unify Quantum mechanics, which describes three of the fundamental forces of nature String theory is a still-developing scientific approach to Theoretical physics, whose original building blocks are one-dimensional extended objects called strings In Theoretical physics, M-theory is a new limit of String theory in which 11 dimensions of Spacetime may be identified Other approaches to this problem include Loop quantum gravity and Noncommutative geometry. Loop quantum gravity (LQG, also known as loop gravity and Quantum geometry, is a proposed quantum theory of Spacetime which attempts to reconcile the theories Noncommutative geometry, or NCG, is a branch of Mathematics concerned with the possible spatial interpretations of Algebraic structures for which the At the Planck scale, the strength of gravity is expected to become comparable to the other forces, and it is theorized that all the fundamental forces are unified at that scale, but the exact mechanism of this unification remains unknown.

The term Planck scale can also refer to a length scale or time scale. In Physics, length scale is a particular Length or Distance determined with the precision of one order (or a few orders of magnitude

Quantity	SI equivalent
Planck time	5. In Physics, the Planck time ( tP) is the unit of Time in the system of Natural units known as Planck units. 39121 × 10−44 s
Planck mass	2. The Planck mass is the unit of Mass, denoted by m P in the system of Natural units known as Planck units. 17645 × 10−8 kg

The Planck length is related to Planck energy by the uncertainty principle. The Planck length, denoted by \scriptstyle\ell_P \, is the unit of Length approximately 1 In Physics, the unit of Energy in the system of Natural units known as Planck units is called the Planck energy, denoted by E P In Quantum physics, the Heisenberg uncertainty principle states that locating a particle in a small region of space makes the Momentum of the particle uncertain At this scale, the concepts of size and distance break down, as quantum indeterminacy becomes virtually absolute. Quantum indeterminacy is the apparent necessary incompleteness in the description of a Physical system, that has become one of the characteristics of the standard Because the Compton wavelength is roughly equal to the Schwarzschild radius of a black hole at the Planck scale, a photon with sufficient energy to probe this realm would yield no information whatsoever. The Compton wavelength \lambda \ of a particle is given by \lambda = \frac{h}{m c} = 2 \pi \frac{\hbar}{m c} \, where The Schwarzschild radius (sometimes historically referred to as the gravitational radius) is a characteristic Radius associated with every Mass. A black hole is a theoretical region of space in which the Gravitational field is so powerful that nothing not even Electromagnetic radiation (e Any photon energetic enough to precisely measure a Planck-sized object could actually create a particle of that dimension, but it would be massive enough to immediately become a black hole (a. k. a a Planck particle), thus completely distorting that region of space, and swallowing the photon. A Planck particle is a hypothetical Subatomic particle, defined as a tiny Black hole whose Compton wavelength is the same as its Schwarzschild radius This is the most extreme example possible of the uncertainty principle, and explains why only a quantum gravity theory reconciling general relativity with quantum mechanics will allow us to understand the dynamics of space-time at this scale. In Quantum physics, the Heisenberg uncertainty principle states that locating a particle in a small region of space makes the Momentum of the particle uncertain Quantum gravity is the field of Theoretical physics attempting to unify Quantum mechanics, which describes three of the fundamental forces of nature General relativity or the general theory of relativity is the geometric theory of Gravitation published by Albert Einstein in 1916 Quantum mechanics is the study of mechanical systems whose dimensions are close to the Atomic scale such as Molecules Atoms Electrons SpaceTime is a patent-pending three dimensional graphical user interface that allows end users to search their content such as Google Google Images Yahoo! YouTube eBay Amazon and RSS Planck scale dynamics is important for cosmology because if we trace the evolution of the cosmos back to the very beginning, at some very early stage the universe should have been so hot that processes involving energies as high as the Planck energy (corresponding to distances as short as the Planck length) may have occurred. This period is therefore called the Planck era or Planck epoch. In Physical cosmology, the Planck epoch (or Planck era) named after Max Planck, is the earliest period of Time in the history of the Universe

Contents 1 Theoretical ideas 2 Experiments probing the Planck Scale 3 Sub-Planck physics 4 See also 5 References 6 External links

Theoretical ideas

The nature of reality at the Planck scale is the subject of much debate in the world of physics, as it relates to a surprisingly broad range of topics. Physics (Greek Physis - φύσις in everyday terms is the Science of Matter and its motion. It may, in fact, be a fundamental aspect of the universe. In terms of size, the Planck scale is unimaginably small (many orders of magnitude smaller than a proton). In terms of energy, it is unimaginably 'hot' and energetic. The wavelength of a photon (and therefore its size) decreases as its frequency or energy increases. In Physics wavelength is the distance between repeating units of a propagating Wave of a given Frequency. In Physics, the photon is the Elementary particle responsible for electromagnetic phenomena Frequency is a measure of the number of occurrences of a repeating event per unit Time. The fundamental limit for a photon's energy is the Planck energy, for the reasons cited above. In Physics, the unit of Energy in the system of Natural units known as Planck units is called the Planck energy, denoted by E P This makes the Planck scale a fascinating realm for speculation by theoretical physicists from various schools of thought. Theoretical physics employs Mathematical models and Abstractions of Physics in an attempt to explain experimental data taken of the natural world Is the Planck scale domain a seething mass of virtual black holes? Is it a fabric of unimaginably fine loops or a spin foam network? Is it interpenetrated by innumerable Calabi-Yau manifolds,^[1] which connect our 3-dimensional universe with a higher dimensional space? Perhaps our 3-D universe is 'sitting' on a 'brane'^[2] which separates it from a 2, 5, or 10-dimensional universe and this accounts for the apparent 'weakness' of gravity in ours. In Physics, a virtual particle is a particle that exists for a limited time and space introducing uncertainty in their energy and momentum due to the Heisenberg Uncertainty Loop quantum gravity (LQG, also known as loop gravity and Quantum geometry, is a proposed quantum theory of Spacetime which attempts to reconcile the theories In Physics, a spin foam is a topological structure made out of two-dimensional faces that represents one of the configurations that must be summed to obtain a Feynman's In mathematics Calabi&ndashYau manifolds are compact Kähler manifolds whose Canonical bundle is trivial In Theoretical physics, a membrane, brane, or p -brane is a spatially extended mathematical concept that appears in String theory These approaches, among several others, are being considered to gain insight into Planck scale dynamics. This would allow physicists to create a unified description of all the fundamental forces. In Physics, a fundamental interaction or fundamental force is a mechanism by which particles interact with each other and which cannot be explained in terms

Experiments probing the Planck Scale

Experimental evidence of Planck scale dynamics is difficult to obtain, and until quite recently was scant to non-existent. Although it remains impossible to probe this realm directly, as those energies are well beyond the capability of any current or planned particle accelerator, there possibly was a time when the universe itself achieved Planck scale energies, and we have measured the afterglow of that era with instruments such as the WMAP probe, which recently accumulated sufficient data to allow scientists to probe back to the first trillionth of a second after the Big Bang, near the electroweak phase transition. The Big Bang is the cosmological model of the Universe that is best supported by all lines of scientific evidence and Observation. In Particle physics, the electroweak interaction is the unified description of two of the four Fundamental interactions of nature Electromagnetism and the This is still several orders of magnitude away from the Planck epoch, when the universe was at the Planck scale, but planned probes such as Planck Surveyor and related experiments such as IceCube expect to greatly improve on current astrophysical measurements. In Physical cosmology, the Planck epoch (or Planck era) named after Max Planck, is the earliest period of Time in the history of the Universe The Planck satellite is a Spacecraft built in the Cannes Mandelieu Space Center, that is designed to observe the anisotropies of the cosmic microwave The IceCube Neutrino Observatory is a Neutrino Telescope currently under construction at the Amundsen-Scott South Pole Station. Recently; results from the Relativistic Heavy Ion Collider have pushed back the particle physics frontier to discover the fluid nature of the quark-gluon plasma, and this process will be augmented by the Large Hadron Collider coming online soon at CERN, pushing back the 'cosmic clock' for particle physics still further. The Relativistic Heavy Ion Collider (RHIC pronounced like " Rick " ˈrɪk is a heavy- Ion Collider located at and operated by Brookhaven A quark-gluon plasma (QGP is a phase of Quantum chromodynamics (QCD which exists at extremely high Temperature and/or Density. The European Organization for Nuclear Research (Organisation Européenne pour la Recherche Nucléaire known as CERN This may add to our understanding of Planck scale dynamics, and sharpen our knowledge of what evolves from that state. No experiment current or planned, however, will allow us to precisely probe or completely understand the Planck scale. Nonetheless, we have already accumulated enough data to narrow the field of workable inflationary universe theories, and to eliminate some theorized extensions to the Standard Model. In Physical cosmology, cosmic inflation is the idea that the nascent Universe passed through a phase of exponential expansion that The Standard Model of Particle physics is a theory that describes three of the four known Fundamental interactions together with the Elementary particles

Sub-Planck physics

Sub-Planck refers to hypothetical, speculative, and conjectural physics beyond or smaller than the Planck scale.

The Elegant Universe^[1] by Brian Greene discusses briefly the strange world of the sub-Planck and how it "creates" the quantum universe by its averages. The Elegant Universe Superstrings Hidden Dimensions and the Quest for the Ultimate Theory (ISBN 0-375-70811-1 is a Book by Brian Greene published in Brian Greene (born February 9 1963 is a Theoretical physicist and one of the best-known string theorists. In his later work, The Fabric of the Cosmos, Greene states that "the familiar notion of space and time do not extend into the sub-Planckian realm, which suggests that space and time as we currently understand them may be mere approximations to more fundamental concepts that still await our discovery. The Fabric of the Cosmos: Space Time and the Texture of Reality ( 2004) is the second book on Theoretical physics, ”

See also

• Planck units
• Planck epoch
• Planck particle
• Quantum gravity

References

External links

• The Planck scale: relativity meets quantum mechanics meets gravity from 'Einstein Light' at UNSW
• The Planck Era from U of Tennessee Astrophysics pages
• Higher-Dimensional Algebra and Planck-Scale Physics by John C. Baez

John Carlos Baez (born 1961 is an American mathematical physicist at the University of California Riverside.

---

© 2009 citizendia.org; parts available under the terms of GNU Free Documentation License, from http://en.wikipedia.org
Dapyx Software network: MP3 Explorer | Ebook Manager | Zenithic