scholarly journals Limits on spacetime foam

2011 ◽  
Vol 83 (8) ◽  
Author(s):  
Wayne A. Christiansen ◽  
Y. Jack Ng ◽  
David J. E. Floyd ◽  
Eric S. Perlman
Keyword(s):  
2002 ◽  
Vol 17 (15n17) ◽  
pp. 1135-1145 ◽  
Author(s):  
D. V. AHLUWALIA

The talk centers around the question: Can general-relativistic description of physical reality be considered complete? On the way I argue how – unknown to many a physicists, even today – the "forty orders of magnitude argument" against quantum gravity phenomenology was defeated more than a quarter of a century ago, and how we now stand at the possible verge of detecting a signal for the spacetime foam, and studying the gravitationally-modified wave particle duality using superconducting quantum interference devices.


2000 ◽  
Vol 477 (4) ◽  
pp. 424-428 ◽  
Author(s):  
Ronald J. Adler ◽  
Ilya M. Nemenman ◽  
James M. Overduin ◽  
David I. Santiago

Entropy ◽  
2000 ◽  
Vol 2 (1) ◽  
pp. 26-38 ◽  
Author(s):  
Remo Garattini
Keyword(s):  

2009 ◽  
Author(s):  
Y. Jack Ng ◽  
Shaaban Khalil
Keyword(s):  

Universe ◽  
2021 ◽  
Vol 7 (12) ◽  
pp. 495
Author(s):  
Steven Carlip

Perhaps the cosmological constant really is huge at the Planck scale, but is “hidden” by Planck scale quantum fluctuations of spacetime. I briefly review this proposal and provide some evidence, coming from a simplified midisuperspace model, that an appropriate “foamy” structure can do the job of hiding a large cosmological constant, and can persist under time evolution.


Author(s):  
Steven Carlip

Abstract Wheeler's conjectured "spacetime foam" -- large quantum fluctuations of spacetime at the Planck scale -- could have important implications for quantum gravity, perhaps even explaining why the cosmological constant seems so small. Here I explore this problem in a midisuperspace model consisting of metrics with local spherical symmetry. Classically, an infinite class of ``foamy'' initial data can be constructed, in which cancellations between expanding and contracting regions lead to a small average expansion even if Λ is large. Quantum mechanically, the model admits corresponding stationary states, for which the probability current is also nearly zero. These states appear to describe a self-reproducing spacetime foam with very small average expansion, effectively hiding the cosmological constant.


2014 ◽  
Vol 29 (19) ◽  
pp. 1430018 ◽  
Author(s):  
F. R. Klinkhamer

Certain exact solutions of the Einstein field equations over nonsimply-connected manifolds are reviewed. These solutions are spherically symmetric and have no curvature singularity. They provide a regularization of the standard Schwarzschild solution with a curvature singularity at the center. Spherically symmetric collapse of matter in ℝ4 may result in these nonsingular black-hole solutions, if quantum-gravity effects allow for topology change near the center or if nontrivial topology is already present as a remnant from a quantum spacetime foam.


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