Spacetime could be simultaneously continuous and discrete, in the same way that information can be
Video abstract for the article 'Spacetime could be simultaneously continuous and discrete, in the same way that information can be 'by Achim Kempf (Achim Kempf 2010 New J. Phys. 12 115001)
Read the full article in New Journal of Physics at http://iopscience.iop.org/1367-2630/12/11/115001/fulltext/.
GENERAL SCIENTIFIC SUMMARY
Introduction and background. To unify quantum theory and general relativity is difficult in large part because of a basic dilemma: general relativity indicates that spacetime should be a continuum, but quantum field theory indicates that spacetime should be discrete, with a spacing at the Planck length of 10−35 m or larger. Correspondingly, there are candidate quantum gravity theories in which it is assumed that spacetime is continuous, while there are competing theories in which spacetime is assumed to be discrete. In the former theories it is difficult to ensure the absence of infinities, while in the latter theories it tends to be difficult to ensure that a continuum emerges.
Main results. Here, aiming to resolve this dilemma, we present results that show that spacetime could be simultaneously continuous and discrete, in the same way that information can be. The transformation rules between continuous and discrete representations of information are described in Shannon's sampling theory, which is in ubiquitous use in all signal processing. In this paper, the underlying mathematics has been generalized and applied to physical fields and spacetime itself. One of the key results is the finding that the local curvature of spacetime can be understood to be a local variation in its density of degrees of freedom, i.e., in the local information carrying capacity of spacetime.
Wider implications. The new information-theoretic concept of a spacetime that is both continuous and discrete could be very helpful for describing spacetime both general relativistically and quantum theoretically.