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Ask Ethan #91: Does Quantum Gravity Need String Theory? (Synopsis) [Starts With A Bang]
“I just think too many nice things have happened in string theory for it to be all wrong. Humans do not understand it very well, but I just don’t believe there is a big cosmic conspiracy that created this incredible thing that has nothing to do with the real world.” –Edward Witten
It’s a difficult fact to accept: our two most fundamental theories that describe reality, General Relativity for gravitation and the Standard Model / Quantum Field Theory for the other three forces, are fundamentally incompatible with one another. When an electron moves through a double slit, for example, its gravitational field can’t move through both slits, at least not without a quantum theory of gravity.
Image credit: ©2012 Perimeter Institute for Theoretical Physics, via https://www.perimeterinstitute.ca/research/research-areas/quantum-foundations/more-quantum-foundations.
String Theory is often touted as the only game in town as far as formulating a quantum theory of gravity is concerned, but in fact there are five viable options, each with different pros, cons, and approaches to the problem. Many of them, in fact, have undergone significant developments in the past 5-10 years, something String Theory cannot claim.
Image credit: flickr gallery of J. Gabas Esteban.
Come read the whole story — by your popular demand — on this edition of Ask Ethan.
Source: http://scienceblogs.com/startswithabang/2015/06/05/ask-ethan-91-does-quantum-gravity-need-string-theory-synopsis/
