'T was noted in heaven, 't was felt in hell, And echo caught faintly the noise as it fell... Abstract By analyzing a gedanken experiment designed to measure the distance l between two spatially separated points, we find that this distance cannot be measured with uncertainty less than (ll 2 P) 1/3 , considerably larger than the Planck scale l P (or the… (More)
We show that quantum mechanics and general relativity limit the speed nu of a simple computer (such as a black hole) and its memory space I to I(nu2) less, similar(t(-2))P, where t(P) is the Planck time. We also show that the lifetime of a simple clock and its precision are similarly limited. These bounds and the holographic bound originate from the same… (More)
INTRODUCTION The aim of this study was to evaluate the outcome of Osteoplug, a novel biodegradable polymer burr-hole cover implant, used in patients with burr holes done for drainage of chronic subdural haematoma. METHODS 12 patients with chronic subdural haematoma had Osteoplug implants inserted into their burr holes after evacuation of the haematoma.… (More)
At Planck-scale, spacetime is " foamy " due to quantum fluctuations predicted by quantum gravity. Here we consider the possibility of using spacetime foam-induced phase incoherence of light from distant galaxies and gamma-ray bursters to probe Planck-scale physics. In particular, we critically examine the cumulative effects of spacetime fluctuations over a… (More)
A recent paper (gr-qc/9909017) criticizes our work on the structure of spacetime foam. Its authors argue that the quantum uncertainty limit for the position of the quantum clock in a gedanken timing experiment, obtained by Wigner and used by us, is based on unrealistic assumptions. Here we point out some flaws in their argument. We also discuss their other… (More)
Using the nonperturbative Schwinger-Dyson equation, we show that chiral symmetry is dynamically broken in QED at weak gauge couplings when an external magnetic field is present and that chiral symmetry is restored at temperatures above T c ≃ α π 2 2π|eH|, where α is the fine structure constant and H is the magnetic field strength.
Due to quantum fluctuations, spacetime is foamy on small scales. The degree of foaminess is found to be consistent with the holographic principle. One way to detect spacetime foam is to look for halos in the images of distant quasars. Applying the holographic foam model to cosmology we "predict" that the cosmic energy density takes on the critical value;… (More)
We examine the interplay between recent advances in quantum gravity and the problem of turbulence. In particular, we argue that in the gravitational context the phenomenon of turbulence is intimately related to the properties of spacetime foam. In this framework we discuss the relation of turbulence and holography and the interpretation of the Kolmogorov… (More)