Stuart Clarke, New Scientist, 4 January 2014
Summary of above article
The article discusses the possibility of interactions between matter/quanta on the one hand and spacetime on the other, and in particular deals with the work of Giovanni Amelino-Camelia at the University of Rome La Sapienza. This is in connection with a powerful burst of gamma radiation from a galaxy at a distance of 500 million light years detected in 2005, and another much more distant burst of radiation observed in 2013.
The controversial aspect of these observations was the claim that the lower energy range of the radiation had arrived hundreds of seconds before the higher energy radiation, which on the face of it contradicts relativity’s claim that all light travels at the same speed. But such an outcome might be consistent with the hypothesis that spacetime is a quantum foam, in which lower energy/longer wavelength quanta could progress faster than higher energy/shorter wavelength particles. String theory’s view of spacetime is seen as possibly consistent with these observations.
However, observations of gamma ray bursts by other astronomers have failed to replicate Amelino-Camelia’s findings, and at the moment further observations involving both neutrinos and gamma ray bursts are awaited.
Nevertheless, even at the present stage many physicists conceive spacetime as comprising some form of structure or network.