Validity of Semiclassical Gravity in the Stochastic Gravity Approach
... As we recalled in the introduction this theory is in some sense unique as a theory that describes the interaction of a classical gravitational field with quantum matter. As an effective theory it should break down at Planck scales. Also, from the right hand side of the semiclassical Einstein equatio ...
... As we recalled in the introduction this theory is in some sense unique as a theory that describes the interaction of a classical gravitational field with quantum matter. As an effective theory it should break down at Planck scales. Also, from the right hand side of the semiclassical Einstein equatio ...
Emergence in Holographic Scenarios for Gravity - Philsci
... Accordingly, there is a finite number of degrees of freedom in a black hole system. ’t Hooft carried the argument one step further by pointing out that if a spherical volume V is bounded by a surface A, the total number of possible states and the entropy inside A are maximized if the volume contain ...
... Accordingly, there is a finite number of degrees of freedom in a black hole system. ’t Hooft carried the argument one step further by pointing out that if a spherical volume V is bounded by a surface A, the total number of possible states and the entropy inside A are maximized if the volume contain ...
Field Theory on Curved Noncommutative Spacetimes
... describe NC gravity and field theories. As ingredients we use ?-products instead of abstract operator algebras. This approach is called deformation quantization [20] and has the advantage that the quantum theory is formulated in terms of the classical objects, thus allowing us to study deviations (p ...
... describe NC gravity and field theories. As ingredients we use ?-products instead of abstract operator algebras. This approach is called deformation quantization [20] and has the advantage that the quantum theory is formulated in terms of the classical objects, thus allowing us to study deviations (p ...
bern
... • We are interested in UV finiteness because it would imply a new symmetry or non-trivial dynamical mechanism. The discovery of either would have a fundamental impact on our understanding of gravity. • Non-perturbative issues and viable models of Nature are not the goal for now. Understanding the me ...
... • We are interested in UV finiteness because it would imply a new symmetry or non-trivial dynamical mechanism. The discovery of either would have a fundamental impact on our understanding of gravity. • Non-perturbative issues and viable models of Nature are not the goal for now. Understanding the me ...
Ashtekar.pdf
... continuum at all scales of interest to physics under consideration. This assumption is reasonable for weak interactions. In the gravitational case, by contrast, the scale of interest is given by the Planck length Pl and there is no physical basis to pre-suppose that the continuum picture should be ...
... continuum at all scales of interest to physics under consideration. This assumption is reasonable for weak interactions. In the gravitational case, by contrast, the scale of interest is given by the Planck length Pl and there is no physical basis to pre-suppose that the continuum picture should be ...
2 + 1 dimensional gravity as an exactly soluble system
... canonical analysis which will lead us to consider the moduli space of all homornorphisms of ~ri(~7) into ISO(2,1). How many parameters are required to specify a homomorphism of rrl(S ) (with a Riemann surface of genus > 1) into ISO(2,1), or more generally, into any Lie group G? This question may eas ...
... canonical analysis which will lead us to consider the moduli space of all homornorphisms of ~ri(~7) into ISO(2,1). How many parameters are required to specify a homomorphism of rrl(S ) (with a Riemann surface of genus > 1) into ISO(2,1), or more generally, into any Lie group G? This question may eas ...
String theory as a Lilliputian world
... requires a regularization. It seemed natural to repeat the successful story of the free particle and use a hypercubic D-dimensional lattice if the wordsheet of the string lived in D-dimensional spacetime, the worldsheet being a connected plaquette lattice surface [1]. The Nambu-Goto action, the area ...
... requires a regularization. It seemed natural to repeat the successful story of the free particle and use a hypercubic D-dimensional lattice if the wordsheet of the string lived in D-dimensional spacetime, the worldsheet being a connected plaquette lattice surface [1]. The Nambu-Goto action, the area ...
Testing the Dimension of Hilbert Spaces
... dimensional real vectors, the maximal value of I achievable with qubits is KG 3. Although the exact values of the Grothendieck constants are still unknown, it is proven that KG 3 < KG [24]: this means that there exists an inequality I which is not saturated by correlations coming from two qubits ...
... dimensional real vectors, the maximal value of I achievable with qubits is KG 3. Although the exact values of the Grothendieck constants are still unknown, it is proven that KG 3 < KG [24]: this means that there exists an inequality I which is not saturated by correlations coming from two qubits ...
Holographic Gravity and the Surface term in the Einstein
... is gauge invariant under the transformations hab → hab + ∂a ξb + ∂b ξa . (Sometimes it is claimed in the literature that a term which is invariant under such infinitesimal gauge transformations will be generally covariant under finite transformations. This is clearly not true and Asur is an instruct ...
... is gauge invariant under the transformations hab → hab + ∂a ξb + ∂b ξa . (Sometimes it is claimed in the literature that a term which is invariant under such infinitesimal gauge transformations will be generally covariant under finite transformations. This is clearly not true and Asur is an instruct ...
Quantum Field Theory Frank Wilczek
... The eld concept came to dominate physics starting with the work of Faraday in the mid-nineteenth century. Its conceptual advantage over the earlier Newtonian program of physics, to formulate the fundamental laws in terms of forces among atomic particles, emerges when we take into account the circum ...
... The eld concept came to dominate physics starting with the work of Faraday in the mid-nineteenth century. Its conceptual advantage over the earlier Newtonian program of physics, to formulate the fundamental laws in terms of forces among atomic particles, emerges when we take into account the circum ...
Unification of Gravity and Electromagnetism
... remarkably similar from a purely functional form. They both follow the so-called inverse square law, but they are considered to be two di↵erent forces by modern physics. The Coulomb constant ke and the Newton gravitational constant G have very di↵erent values, where Coulomb’s formula require charges ...
... remarkably similar from a purely functional form. They both follow the so-called inverse square law, but they are considered to be two di↵erent forces by modern physics. The Coulomb constant ke and the Newton gravitational constant G have very di↵erent values, where Coulomb’s formula require charges ...
Renormalization group and the Planck scale
... renormalizable theories, the continuum limit is performed by removing the scale L, 1/L → 0, and the functional GL → G∗ approaches a fixed-point action at short distances (see the proposal in Manrique & Reuter [31] for a construction in gravity). In perturbatively renormalizable theories, G∗ is ‘trivi ...
... renormalizable theories, the continuum limit is performed by removing the scale L, 1/L → 0, and the functional GL → G∗ approaches a fixed-point action at short distances (see the proposal in Manrique & Reuter [31] for a construction in gravity). In perturbatively renormalizable theories, G∗ is ‘trivi ...
Here - Blogs at UMass Amherst
... formulate the Standard Model as a theory after all these QFT developments occurred. In contrast, General Relativity was fully formulated 100 years ago. It has been passed down to us as a geometric theory — “there is no gravitational force, but only geodesic motion in curved spacetime”. And the mathe ...
... formulate the Standard Model as a theory after all these QFT developments occurred. In contrast, General Relativity was fully formulated 100 years ago. It has been passed down to us as a geometric theory — “there is no gravitational force, but only geodesic motion in curved spacetime”. And the mathe ...
Harmony of Scattering Amplitudes: From gauge theory
... This talk will present some recent developments in understanding scattering amplitudes in gauge and gravity theories. • Harmony: Examples of remarkable relations in gauge and gravity theories. • QCD: Brief look at applications of new ideas to LHC physics • Supersymmetric gauge theory: resummation of ...
... This talk will present some recent developments in understanding scattering amplitudes in gauge and gravity theories. • Harmony: Examples of remarkable relations in gauge and gravity theories. • QCD: Brief look at applications of new ideas to LHC physics • Supersymmetric gauge theory: resummation of ...
Quantum Theory and Relativity
... Should quantum theory with relativity not qualify as logic? Physics suggests that a natural way to combine quantum theory, special relativity, and interaction is through a non-linear quantum field. Enormous progress on this problem has been made over the past forty years. This includes showing that ...
... Should quantum theory with relativity not qualify as logic? Physics suggests that a natural way to combine quantum theory, special relativity, and interaction is through a non-linear quantum field. Enormous progress on this problem has been made over the past forty years. This includes showing that ...
yale - Particle Theory Group
... gravity gets stronger at extremely high energies (or short distances). it gets stronger at lower energies if there are extra dimensions…. ...
... gravity gets stronger at extremely high energies (or short distances). it gets stronger at lower energies if there are extra dimensions…. ...
Naturalness via scale invariance and non-trivial UV fixed points in a 4d O(N) scalar field model in the large-N limit
... the momentum cutoff and leads to the fine-tuning problem. If a large cutoff is to be maintained, either the effective Higgs mass is of the order of the cutoff or the bare mass must be fine-tuned to cancel the radiative correction (at each order). We already mentioned the difficulties with a very lar ...
... the momentum cutoff and leads to the fine-tuning problem. If a large cutoff is to be maintained, either the effective Higgs mass is of the order of the cutoff or the bare mass must be fine-tuned to cancel the radiative correction (at each order). We already mentioned the difficulties with a very lar ...
Quantum Gravity as Sum over Spacetimes
... such that the correlator O(xn )O(ym ) falls off exponentially like e−m ph |xn −ym | for g0 → g0c when |xn − ym |, but not |n − m|, is kept fixed in the limit g0 → g0c . Thus we have created a picture where the underlying lattice spacing goes to zero while the physical mass (or the correlation leng ...
... such that the correlator O(xn )O(ym ) falls off exponentially like e−m ph |xn −ym | for g0 → g0c when |xn − ym |, but not |n − m|, is kept fixed in the limit g0 → g0c . Thus we have created a picture where the underlying lattice spacing goes to zero while the physical mass (or the correlation leng ...
Dilute Fermi and Bose Gases - Subir Sachdev
... LF is just a free field theory. Like ZB , ZF has a quantum critical point at µ = 0, T = 0 and we will discuss its properties; in particular, we will show that all possible fermionic nonlinearities are irrelevant near it. The reader should not be misled by the apparently trivial nature of the model i ...
... LF is just a free field theory. Like ZB , ZF has a quantum critical point at µ = 0, T = 0 and we will discuss its properties; in particular, we will show that all possible fermionic nonlinearities are irrelevant near it. The reader should not be misled by the apparently trivial nature of the model i ...
Von Neumann algebra automorphisms and time
... the idea that one can extend the notion of time flow to general covariant theories, but this flow depends on the thermal state of the system. More in detail, we will argue that the notion of time flow extends naturally to general covariant theories, provided that: i. We interpret the time flow as a ...
... the idea that one can extend the notion of time flow to general covariant theories, but this flow depends on the thermal state of the system. More in detail, we will argue that the notion of time flow extends naturally to general covariant theories, provided that: i. We interpret the time flow as a ...
Infrared and ultraviolet cutoffs of quantum field theory
... near future energies available in accelerator physics. This second scenario suggests that QM, as we know it today, might fail not only above the 10 TeV scale, but also that one could find unexpected effects at the quantum level for phenomena with a characteristic scale of 10−2 − 10−4 eV, for example ...
... near future energies available in accelerator physics. This second scenario suggests that QM, as we know it today, might fail not only above the 10 TeV scale, but also that one could find unexpected effects at the quantum level for phenomena with a characteristic scale of 10−2 − 10−4 eV, for example ...
String Theory 101 - King`s College London
... an infinite series of divergences which must be subtracted by inventing an infinite series of new interactions, thereby removing any predictive power. Thus we cannot use the methods of QFT as a fundamental principle for gravity. The third problem I want to mention is more technical. Quantum field th ...
... an infinite series of divergences which must be subtracted by inventing an infinite series of new interactions, thereby removing any predictive power. Thus we cannot use the methods of QFT as a fundamental principle for gravity. The third problem I want to mention is more technical. Quantum field th ...
why do physicists think that there are extra dimensions
... long ago philosopher Immanuel Kant gave a ~500 page proof that space and time are a priori however to make sense of quantum gravity, not to mention the Big Bang singularity, this cannot be true in the real theory of everything, spacetime should be emergent. ...
... long ago philosopher Immanuel Kant gave a ~500 page proof that space and time are a priori however to make sense of quantum gravity, not to mention the Big Bang singularity, this cannot be true in the real theory of everything, spacetime should be emergent. ...
Why the Glove of Mathematics Fits the Hand of the Natural Sciences
... mathematics and the physical sciences? Because there is a necessary connection between relativity theory and quantum mechanics by means of the special number 137+—according to the astounding formula, alpha (α-1) equals hc/2pi e2 equals 137+, where h stands for Planck’s quantum constant of action, c ...
... mathematics and the physical sciences? Because there is a necessary connection between relativity theory and quantum mechanics by means of the special number 137+—according to the astounding formula, alpha (α-1) equals hc/2pi e2 equals 137+, where h stands for Planck’s quantum constant of action, c ...
Loop Quantum Gravity and Effective Matter Theories
... the non-renormalizability of gravity is support the thesis that quantum corrections have negligible effects on the gravitational interaction which is extremely weak and therefore argue that the unification of GR and QM might be useless, at least from an empirical point of view. We are aware that thi ...
... the non-renormalizability of gravity is support the thesis that quantum corrections have negligible effects on the gravitational interaction which is extremely weak and therefore argue that the unification of GR and QM might be useless, at least from an empirical point of view. We are aware that thi ...