Calculation of X-Ray Signals from Karolyhazy Hazy Space-Time

Karolyhazy's hazy space-time model, invented for breaking down macroscopic interferences, employs wave-like gravity disturbances. If so, then electric charges would radiate permanently. Here we discuss the observational consequences of the radiation. We find that such radiation is excluded by common experimental situations.Comment: 7 pages, PlainTe

Space-time in light of Karolyhazy uncertainty relation

General relativity and quantum mechanics provide a natural explanation for the existence of dark energy with its observed value and predict its dynamics. Dark energy proves to be necessary for the existence of space-time itself and determines the rate of its stability.Comment: 5 pages, Two misprints are correcte

Cosmological implications of Karolyhazy uncertainty relation

Karolyhazy uncertainty relation, which can be viewed also as a relation between UV and IR scales in the framework of an effective quantum field theory satisfying a black hole entropy bound, strongly favors the existence of dark energy with its observed value. Here we estimate the dynamics of dark energy predicted by the Karolyhazy relation during the cosmological evolution of the universe.Comment: 4 pages, Version to appear in PLB, a few comments and a reference adde

Random versus holographic fluctuations of the background metric. II. Note on the dark energies arising due to microstructure of space-time

Over the last few years a certain class of dark-energy models decaying inversely proportional to the square of the horizon distance emerged on the basis either of Heisenberg uncertainty relations or of the uncertainty relation between the four-volume and the cosmological constant. The very nature of these dark energies is understood to be the same, namely it is the energy of background space/metric fluctuations. Putting together these uncertainty relations one finds that the model of random fluctuations of the background metric is favored over the holographic one.Comment: 3 page

Gravitationally-Induced Quantum Superpopsition Reduction with Large Extra Dimensions

A gravity-driven mechanism (``objective reduction'') proposed to explain quantum state reduction is analyzed in light of the possible existence of large extra dimensions in the ADD scenario. By calculating order-of-magnitude estimates for nucleon superpositions, it is shown that if the mechanism at question is correct, constraints may be placed on the number and size of extra dimensions. Hence, measurement of superposition collapse times ({\it e.g.} through diffraction or reflection experiments) could represent a new probe of extra dimensions. The influence of a time-dependent gravitational constant on the gravity-driven collapse scheme with and without the presence of extra dimensions is also discussed.Comment: 22 pp; 1 postscript figure Expanded version of previous submission To appear in Phys Rev

Testing Gravity-Driven Collapse of the Wavefunction via Cosmogenic Neutrinos

It is pointed out that the Diosi-Penrose ansatz for gravity-induced quantum state reduction can be tested by observing oscillations in the flavor ratios of neutrinos originated at cosmological distances. Since such a test would be almost free of environmental decoherence, testing the ansatz by means of a next generation neutrino detector such as IceCube would be much cleaner than by experiments proposed so far involving superpositions of macroscopic systems. The proposed microscopic test would also examine the universality of superposition principle at unprecedented cosmological scales.Comment: 4 pages; RevTeX4; Essentially the version published in PR

Operational definition of (brane induced) space-time and constraints on the fundamental parameters

First we contemplate the operational definition of space-time in four dimensions in light of basic principles of quantum mechanics and general relativity and consider some of its phenomenological consequences. The quantum gravitational fluctuations of the background metric that comes through the operational definition of space-time are controlled by the Planck scale and are therefore strongly suppressed. Then we extend our analysis to the braneworld setup with low fundamental scale of gravity. It is observed that in this case the quantum gravitational fluctuations on the brane may become unacceptably large. The magnification of fluctuations is not linked directly to the low quantum gravity scale but rather to the higher-dimensional modification of Newton's inverse square law at relatively large distances. For models with compact extra dimensions the shape modulus of extra space can be used as a most natural and safe stabilization mechanism against these fluctuations.Comment: 9 page

Operational definition of (brane induced) space-time and constraints on the fundamental parameters

First we contemplate the operational definition of space-time in four dimensions in light of basic principles of quantum mechanics and general relativity and consider some of its phenomenological consequences. The quantum gravitational fluctuations of the background metric that comes through the operational definition of space-time are controlled by the Planck scale and are therefore strongly suppressed. Then we extend our analysis to the braneworld setup with low fundamental scale of gravity. It is observed that in this case the quantum gravitational fluctuations on the brane may become unacceptably large. The magnification of fluctuations is not linked directly to the low quantum gravity scale but rather to the higher-dimensional modification of Newton's inverse square law at relatively large distances. For models with compact extra dimensions the shape modulus of extra space can be used as a most natural and safe stabilization mechanism against these fluctuations.Comment: 9 page