Gravity and Strings

By S. Giddings. 2005

578 citations recorded by the source corpus.

This is a broad-brush review of how string theory addresses several important questions of gravitational physics. The problem of non-renormalizability is first reviewed, followed by introduction of string theory as an ultraviolet-finite theory of gravity. String theory’s successes also include predicting both gauge theory and fermions. The difficulty of extra dimensions becomes a possible virtue, when one notes that these lead to mechanisms to explain fermion generations, as well as a means to break the large gauge symmetries of string theory. Finally, a long standing problem of string theory, that of fixing the size and shape of the extra dimensions, has recently been addressed and may shed light on the origin of the cosmological constant, the ultimate fate of our universe, as well as the question of why gravity is so weak. 1. PUZZLES OF GRAVITY In this lecture I plan to convey the basic ideas of string theory, particularly as they relate to some puzzles of gravitational physics. At my home institution, string theory is a two to three quarter class, just to teach the foundation, so the best that can be done here is to give a very impressionistic view of some of the features of the theory, introducing some of the central ideas. (For the same reason, I will only give a brief guide to the literature at the end, rather than inclusive references.) Nonetheless, I will also endeavor to bring the reader up to speed on some of the newest – and most bizarre – ideas of string theory, particularly pertaining to cosmology and the fate of the Universe. We’ll begin with the question of the day.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/a9a983a60d80d02b9446b4395486490f88798bcd

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Citations in the corpus

Gauging the Carroll algebra and ultra-relativistic gravity (2015, background): “This leads to the so-called Weitzenböck connection (see for example [39]).”
Born–Infeld inspired modifications of gravity (2017, background): “It turns out that it is not possible to have a well defined point-like source generating both mass and charge of the Reissner-Nordström geometry and, at the same time, being a solution of the Einstein equations everywhere [287].”
Nonmetricity formulation of general relativity and its scalar-tensor extension (2018, background): “[33] Tomas Ortin, Gravity and Strings , Cambridge Monographs on Mathematical Physics (Cambridge University Press, 2015).”
Non-Abelian discrete gauge symmetries in 4d string models (2012, background): “4 of [38]) for building a Riemannian metric Gab(φ) for M in terms of the elements of Iso(M) and Kp.”
Elements of Vasiliev theory (2014, background): “The relevant references include [98–101] and [102] for the references on the original papers by Cartan, Weyl, Sciama, Kibble.”
Transplanckian axions!? (2015, background): “The supergravity perspective regards D-branes as extended, extremal black hole solutions [73], and so they are in a sense the stringy version of the instantons discussed above.”
Black Holes in f(R) theories (2009, unknown): “The most general static and spherically symmetric D 4 dimensional metric can be written as (see [18]):”
The classical double copy for Taub–NUT spacetime (2015, background): “For the (anti-) self-dual case, the gauge and gravity solutions can be interpreted as instantons (see also [64]).”