A Brief Introduction into Quantum Gravity and Quantum Cosmology
... this requires a radical reconstruction of the theory, and in particular, the rejection of a Riemannian geometry dealing, as we see here, with values unobservable in principle, and perhaps also the rejection of our ordinary concepts of space and time, modifying them by some much deeper and nonevident ...
... this requires a radical reconstruction of the theory, and in particular, the rejection of a Riemannian geometry dealing, as we see here, with values unobservable in principle, and perhaps also the rejection of our ordinary concepts of space and time, modifying them by some much deeper and nonevident ...
Neitzke: What is a BPS state?
... and indeed does — imply that the BPS degeneracy Ω(γ) jumps when we vary parameters. So these “invariants” are not as invariant as one might have hoped! This might seem like a contradiction, since we emphasized that Ω(γ) is invariant under continuous deformations of the G̃-representation H1 . The tro ...
... and indeed does — imply that the BPS degeneracy Ω(γ) jumps when we vary parameters. So these “invariants” are not as invariant as one might have hoped! This might seem like a contradiction, since we emphasized that Ω(γ) is invariant under continuous deformations of the G̃-representation H1 . The tro ...
Goals, models, frameworks and the scientific method
... interested in QED would have simply taken over its methods and results, and progress in the latter field would have been faster. As is well-known, QFT also has applications to condensed matter physics. It can be reformulated to describe a manybody system such as a crystal with local interactions bet ...
... interested in QED would have simply taken over its methods and results, and progress in the latter field would have been faster. As is well-known, QFT also has applications to condensed matter physics. It can be reformulated to describe a manybody system such as a crystal with local interactions bet ...
Unified Field Theory
... governed by the exchange of four particles: the photon for electromagnetic interactions, a neutral Z particle and two charged W particles for weak interaction. As a result of the spontaneous symmetry breaking, the weak force becomes short range and the Z and W bosons acquire masses of 80.4 and 91.2 ...
... governed by the exchange of four particles: the photon for electromagnetic interactions, a neutral Z particle and two charged W particles for weak interaction. As a result of the spontaneous symmetry breaking, the weak force becomes short range and the Z and W bosons acquire masses of 80.4 and 91.2 ...
The Quantum Theory of General Relativity at Low Energies
... definition including the diagrams calculated in [6] has a slightly different number, but the same qualitative conclusion. The power-law running, instead of the usual logarithm, is a consequence of the dimensionful gravitational coupling. These two results do not exhaust the predictions of the effect ...
... definition including the diagrams calculated in [6] has a slightly different number, but the same qualitative conclusion. The power-law running, instead of the usual logarithm, is a consequence of the dimensionful gravitational coupling. These two results do not exhaust the predictions of the effect ...
Theoretical Particle
... Essential in obtaining the massless particles such as photons and gravitons 1019 GeV ( string tension: Planck scale proton 1GeV 0.17 mg ) ...
... Essential in obtaining the massless particles such as photons and gravitons 1019 GeV ( string tension: Planck scale proton 1GeV 0.17 mg ) ...
by Margaret L. Silbar
... Regge trajectories, and experiments verified this picture. There were, .however, some problems. To mesh with quantum mechanics and with special relativity, the spacetime in which the relativistic string moves around must have an uncommon number of dimensions-—for example, 10, or perhaps as many as 2 ...
... Regge trajectories, and experiments verified this picture. There were, .however, some problems. To mesh with quantum mechanics and with special relativity, the spacetime in which the relativistic string moves around must have an uncommon number of dimensions-—for example, 10, or perhaps as many as 2 ...
UNVEILING THE ULTIMATE LAWS OF NATURE
... -- Do similar thing for string theory – 10D Æ 4D, etc -- Make predictions, test them Æ tests theory • Don’t need to be at Planck scale to test – always relics – Big Bang, speed of light, dinosaurs • Test, “see” extra dimensions? – Total energy of world is zero, but for 10D world or 4D? – Cosmology o ...
... -- Do similar thing for string theory – 10D Æ 4D, etc -- Make predictions, test them Æ tests theory • Don’t need to be at Planck scale to test – always relics – Big Bang, speed of light, dinosaurs • Test, “see” extra dimensions? – Total energy of world is zero, but for 10D world or 4D? – Cosmology o ...
J.M. Maldacena
... • One can define inclusive, event shape variables for conformal theories • They can be computed at weak and strong coupling • Small angle features governed by the anomalous dimension of twist two operators • Events are more spherically symmetric at strong coupling, but not completely uniform. • In a ...
... • One can define inclusive, event shape variables for conformal theories • They can be computed at weak and strong coupling • Small angle features governed by the anomalous dimension of twist two operators • Events are more spherically symmetric at strong coupling, but not completely uniform. • In a ...
“Superstring theory” syndrome
... The quantity which describes the reactions of elementary particles is the S-matrix or the scattering amplitude. But since it is impossible to calculate it exactly, various approximation methods have been invented. Among them, the most well-organized one is perturbation theory. Among particle physici ...
... The quantity which describes the reactions of elementary particles is the S-matrix or the scattering amplitude. But since it is impossible to calculate it exactly, various approximation methods have been invented. Among them, the most well-organized one is perturbation theory. Among particle physici ...
Document
... When its size is dxd, it is called “d-level” Each state can be classified as pure or mixed ...
... When its size is dxd, it is called “d-level” Each state can be classified as pure or mixed ...
The Second Century of Particle Physics
... • Electroweak unification shows that electromagnetic and weak forces are really just two aspects of the same interaction. • Do strong forces unify with electroweak ones? – If they do, then quarks and leptons become much more closely related particles; it would explain why quarks have just the right ...
... • Electroweak unification shows that electromagnetic and weak forces are really just two aspects of the same interaction. • Do strong forces unify with electroweak ones? – If they do, then quarks and leptons become much more closely related particles; it would explain why quarks have just the right ...
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.The current understanding of gravity is based on Albert Einstein's general theory of relativity, which is formulated within the framework of classical physics. On the other hand, the nongravitational forces are described within the framework of quantum mechanics, a radically different formalism for describing physical phenomena based on probability. The necessity of a quantum mechanical description of gravity follows from the fact that one cannot consistently couple a classical system to a quantum one.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. 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. A recent development is the theory of causal fermion systems which gives quantum mechanics, general relativity, and quantum field theory as limiting cases.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. While any substantial improvement into the present understanding of gravity would aid further work towards unification, study of quantum gravity is a field in it's own right with various branches having different approaches to unification. Although some quantum gravity theories, such as string theory, try to unify gravity with the other fundamental forces, others, such as loop quantum gravity, make no such attempt; instead, they make an effort to quantize the gravitational field while it is kept separate from the other forces. A theory of quantum gravity that is also a grand unification of all known interactions is sometimes referred to as a theory of everything (TOE).One of the difficulties of quantum gravity is that quantum gravitational effects are only expected to become apparent near the Planck scale, a scale far smaller in distance (equivalently, far larger in energy) than what is currently accessible at high energy particle accelerators. As a result, quantum gravity is a mainly theoretical enterprise, although there are speculations about how quantum gravity effects might be observed in existing experiments.