Exploring Quantum Gravity: Bounds on Spectral Dispersion and Space-Time Foam

[audioloop]

prospect to detect spacetime foam experimentally, has been decreasing progressively the upper bounds (if exist space foam) hence no space foam detect yet at least for string based models predictions (and possibly for others models)

Physical Review Letters. 108, 231103 (2012)
Bounds on Spectral Dispersion from Fermi-Detected Gamma Ray Bursts
http://arxiv.org/pdf/1109.5191v2.pdf

...Such limits constrain dispersive effects created, for example, by the spacetime foam of quantum gravity. In the context of quantum gravity, our bounds set M1c2 greater than 525 times the Planck mass, suggesting that spacetime is smooth at energies near and slightly above the Planck mass...
...results in a rather tight bound of M1/MP lanck > 525, suggesting that space is smooth even at energies near and slightly above the Planck mass...----
J. Phys.: Conf. Ser. 283 012022
Stringy Space-Time Foam and High-Energy Cosmic Photons

Physics Letters B
Volume 665, Issue 5, 31 July 2008, Pages 412–417
Derivation of a vacuum refractive index in a stringy space–time foam model
http://arxiv.org/pdf/0804.3566v1.pdf

Physics Letters B
Volume 674, Issue 2, 13 April 2009, Pages 83–86
Probing a possible vacuum refractive index with γ-ray telescopes
http://arxiv.org/pdf/0901.4052v2.pdf

 

[eljose79]

Thank you for sharing these interesting articles on the prospect of detecting spacetime foam experimentally. I am always excited to see advancements in our understanding of quantum gravity and the potential to test its predictions.

The first article you shared, from Physical Review Letters, discusses the bounds on spectral dispersion from gamma ray bursts and how it constrains dispersive effects created by spacetime foam in the context of quantum gravity. These bounds suggest that spacetime is smooth at energies near and slightly above the Planck mass, with a tight bound of M1/MP lanck > 525. This is a significant result, as it indicates that spacetime foam may not be detectable at these energies.

The second and third articles, from J. Phys.: Conf. Ser. and Physics Letters B, explore the possibility of detecting a vacuum refractive index in a stringy space-time foam model using gamma-ray telescopes. These studies propose methods for detecting this effect and calculating the refractive index, which would provide further evidence for the existence of spacetime foam.

Overall, these articles show that while the prospect of detecting spacetime foam experimentally is still a challenging task, progress is being made in understanding its potential effects and how we can test for them. I look forward to seeing future advancements in this area of research and the potential implications for our understanding of the fundamental nature of space and time.