background preloader

Vacuum energy

Vacuum energy
Vacuum energy is an underlying background energy that exists in space throughout the entire Universe. One contribution to the vacuum energy may be from virtual particles which are thought to be particle pairs that blink into existence and then annihilate in a timespan too short to observe. They are expected to do this everywhere, throughout the Universe. The effects of vacuum energy can be experimentally observed in various phenomena such as spontaneous emission, the Casimir effect and the Lamb shift, and are thought to influence the behavior of the Universe on cosmological scales. Origin[edit] Summing over all possible oscillators at all points in space gives an infinite quantity. Vacuum energy can also be thought of in terms of virtual particles (also known as vacuum fluctuations) which are created and destroyed out of the vacuum. Additional contributions to the vacuum energy come from spontaneous symmetry breaking in quantum field theory. Implications[edit] [citation needed] Notes[edit]

It's confirmed: Matter is merely vacuum fluctuations - physics-math - 20 November 2008 Matter is built on flaky foundations. Physicists have now confirmed that the apparently substantial stuff is actually no more than fluctuations in the quantum vacuum. The researchers simulated the frantic activity that goes on inside protons and neutrons. Each proton (or neutron) is made of three quarks - but the individual masses of these quarks only add up to about 1% of the proton's mass. Theory says it is created by the force that binds quarks together, called the strong nuclear force. But it has taken decades to work out the actual numbers. So physicists have developed a method called lattice QCD, which models smooth space and time as a grid of separate points. Gnarly calculation Until recently, lattice QCD calculations concentrated on the virtual gluons, and ignored another important component of the vacuum: pairs of virtual quarks and antiquarks. Quark-antiquark pairs can pop up and momentarily transform a proton into a different, more exotic particle. Crunch time Higgs field

Theory of everything A theory of everything (ToE) or final theory, ultimate theory, or master theory is a hypothetical single, all-encompassing, coherent theoretical framework of physics that fully explains and links together all physical aspects of the universe.[1]:6 Finding a ToE is one of the major unsolved problems in physics. Over the past few centuries, two theoretical frameworks have been developed that, as a whole, most closely resemble a ToE. The two theories upon which all modern physics rests are general relativity (GR) and quantum field theory (QFT). GR is a theoretical framework that only focuses on the force of gravity for understanding the universe in regions of both large-scale and high-mass: stars, galaxies, clusters of galaxies, etc. On the other hand, QFT is a theoretical framework that only focuses on three non-gravitational forces for understanding the universe in regions of both small scale and low mass: sub-atomic particles, atoms, molecules, etc. Historical antecedents[edit] [edit]

Quantum field theory in curved spacetime In particle physics, quantum field theory in curved spacetime is an extension of standard, Minkowski-space quantum field theory to curved spacetime. A general prediction of this theory is that particles can be created by time-dependent gravitational fields (multigraviton pair production), or by time-independent gravitational fields that contain horizons. Description[edit] Interesting new phenomena occur; owing to the equivalence principle the quantization procedure locally resembles that of normal coordinates where the affine connection at the origin is set to zero and a nonzero Riemann tensor in general once the proper (covariant) formalism is chosen; however, even in flat spacetime quantum field theory, the number of particles is not well-defined locally. For non-zero cosmological constants, on curved spacetimes quantum fields lose their interpretation as asymptotic particles. Applications[edit] Approximation to quantum gravity[edit] See also[edit] References[edit] Notes[edit] N.D.

Quantum gravity Quantum gravity (QG) is a field of theoretical physics that seeks to describe the force of gravity according to the principles of quantum mechanics. Although a quantum theory of gravity is needed in order to reconcile general relativity with the principles of quantum mechanics, difficulties arise when one attempts to apply the usual prescriptions of quantum field theory to the force of gravity.[3] From a technical point of view, the problem is that the theory one gets in this way is not renormalizable and therefore cannot be used to make meaningful physical predictions. As a result, theorists have taken up more radical approaches to the problem of quantum gravity, the most popular approaches being string theory and loop quantum gravity.[4] Strictly speaking, the aim of quantum gravity is only to describe the quantum behavior of the gravitational field and should not be confused with the objective of unifying all fundamental interactions into a single mathematical framework.

Zero Point Energy (ZPE) In a recent article in the popular press (The Economist, January 7, 1989, pp. 71-74) it was noted how many of this century's new technologies depend on the Alice-in-Wonderland physics of quantum mechanics, with all of its seeming absurdities. For starters, one begins with the observation that classical physics tells us that atoms, which can be likened to a miniature solar system with electron planets orbiting a nuclear sun, should not exist. The circling electrons should radiate away their energy like microscopic radio antennas and spiral into the nucleus. These are the so-called "logical positivists" who, in a philosophical sense, are like the news reporter whose only interest is the bottom line. However, there are certain conditions in which the uniformity of the background electromagnetic zero-point energy is slightly disturbed and leads to physical effects. What does this have to do with our basic questions? Gravity can thus be understood as a kind of long-range Casimir force. R.

String (physics) In physics, a string is a physical object that appears in string theory and related subjects. Unlike elementary particles, which are zero-dimensional or point-like by definition, strings are one-dimensional extended objects. Theories in which the fundamental objects are strings rather than point particles automatically have many properties that are expected to hold in a fundamental theory of physics. In string theory, the strings may be open (forming a segment with two endpoints) or closed (forming a loop like a circle) and may have other special properties. In theories of particle physics based on string theory, the characteristic length scale of strings is typically on the order of the Planck length, the scale at which the effects of quantum gravity are believed to become significant. As it propagates through spacetime, a string sweeps out a two-dimensional surface called its worldsheet. Strings can be either open or closed.

unification, spacetime foam, quantum vacuum, quantum fluctuations Physics of the early Universe is at the boundary of astronomy and philosophy since we do not currently have a complete theory that unifies all the fundamental forces of Nature at the moment of Creation. In addition, there is no possibility of linking observation or experimentation of early Universe physics to our theories (i.e. it's not possible to `build' another Universe). Our theories are rejected or accepted based on simplicity and aesthetic grounds, plus their power of prediction to later times, rather than an appeal to empirical results. This is a very difference way of doing science from previous centuries of research. Our physics can explain most of the evolution of the Universe after the Planck time (approximately 10-43 seconds after the Big Bang). Another way of seeing this problem is trying to reproduce the Greek philosophers thinking about matter, as applied to spacetime. Cosmic Singularity : Quantum Vacuum: Quantum Fluctuations : Planck Era : Unification: Spacetime Foam :

Brane In string theory and related theories, D-branes are an important class of branes that arise when one considers open strings. As an open string propagates through spacetime, its endpoints are required to lie on a D-brane. The letter "D" in D-brane refers to the fact that we impose a certain mathematical condition on the system known as the Dirichlet boundary condition. The study of D-branes has led to important results, such as the anti-de Sitter/conformal field theory correspondence, which has shed light on many problems in quantum field theory. See also[edit] References[edit] Jump up ^ Moore, Gregory (2005).

Virtual particle In physics, a virtual particle is a transient fluctuation that exhibits many of the characteristics of an ordinary particle, but that exists for a limited time. The concept of virtual particles arises in perturbation theory of quantum field theory where interactions between ordinary particles are described in terms of exchanges of virtual particles. Any process involving virtual particles admits a schematic representation known as a Feynman diagram, in which virtual particles are represented by internal lines. [1][2] Virtual particles do not necessarily carry the same mass as the corresponding real particle, although they always conserve energy and momentum. The longer the virtual particle exists, the closer its characteristics come to those of ordinary particles. They are important in the physics of many processes, including particle scattering and Casimir forces. Antiparticles have been proven to exist and should not be confused with virtual particles or virtual antiparticles.

Spontaneous symmetry breaking Consider the bottom of an empty wine bottle, a symmetrical upward dome with a trough for sediment. If a ball is put in a particular position at the peak of the dome, the circumstances are symmetrical with respect to rotating the wine bottle. But the ball may spontaneously break this symmetry and move into the trough, a point of lowest energy. The bottle and the ball continue to have symmetry, but the system does not.[4] Most simple phases of matter and phase-transitions, like crystals, magnets, and conventional superconductors can be simply understood from the viewpoint of spontaneous symmetry breaking. Spontaneous symmetry breaking in physics[edit] Spontaneous symmetry breaking simplified: - At high energy levels (left) the ball settles in the center, and the result is symmetrical. Particle physics[edit] Chiral symmetry[edit] Chiral symmetry breaking is an example of spontaneous symmetry breaking affecting the chiral symmetry of the strong interactions in particle physics. , where .

Quantum fluctuation In quantum physics, a quantum vacuum fluctuation (or quantum fluctuation or vacuum fluctuation) is the temporary change in the amount of energy in a point in space,[1] as explained in Werner Heisenberg's uncertainty principle. According to one formulation of the principle, energy and time can be related by the relation[2] That means that conservation of energy can appear to be violated, but only for small values of t (time). Quantum fluctuations may have been very important in the origin of the structure of the universe: according to the model of inflation the ones that existed when inflation began were amplified and formed the seed of all current observed structure. Quantum fluctuations of a field[edit] A quantum fluctuation is the temporary appearance of energetic particles out of empty space, as allowed by the uncertainty principle. An extension is applicable to the "uncertainty in time" and "uncertainty in energy" (including the rest mass energy ). at a time to be is . See also[edit]

Antimatter In particle physics, antimatter is material composed of antiparticles, which have the same mass as particles of ordinary matter but have opposite charge and other particle properties such as lepton and baryon number. Encounters between particles and antiparticles lead to the annihilation of both, giving rise to varying proportions of high-energy photons (gamma rays), neutrinos, and lower-mass particle–antiparticle pairs. Setting aside the mass of any product neutrinos, which represent released energy which generally continues to be unavailable, the end result of annihilation is a release of energy available to do work, proportional to the total matter and antimatter mass, in accord with the mass-energy equivalence equation, E=mc2.[1] Antiparticles bind with each other to form antimatter just as ordinary particles bind to form normal matter. For example, a positron (the antiparticle of the electron) and an antiproton can form an antihydrogen atom. History of the concept Notation Positrons

ANU Quantum Random Number Server

Related: