http://www.quora.com/Physics/Is-this-a-watershed-new-discovery-in-physics-is-space-time-still-fundamental-now-that-we-have-the-amplituhedron-for-modeling-quantum-field-theory
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What this work is attempting to do (which it hasn't full achieved yet) is to replace our underlying formulation of quantum field theory with a new formulation.
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What Nima Arkani-Hamed [*] and collaborators are trying to do is, is to replace the building blocks of a theory with particles (rather than fields), elementary interactions and a new space called the Grassmannian. Most importantly, space-time does not appear in this formulation. In a class of theories, this has been shown to reproduce almost all of the results of the path integral formulation of quantum field theory. There are certain very field-y aspects that hasn't been reformulated, most notably vacuum expectation values (of fields) and instantons (to my knowledge). But that is huge progress.
The fact that space-time does not appear to be one of the elementary building blocks, but instead emerges as an interpretation of the results is a fascinating concept. We know that this has to be the case at some level, but I think that this particular avenue physicists find surprising (I think 5 years ago physicists would have muttered something about string field theory). The reason why this could be very important is that some of the deepest conceptual difficulties in quantum gravity are very difficult to formulate because they really require quantum space-time and our formulation takes in space-time as an input, while formally this problem isn't a contradiction, it does mean that space-time is getting in the way of doing calculations. This progress makes very little direct in-roadson these problems, it is beginning to at least create a formalism where space-time is not at the heart of the formulation.
* Full-disclosure: Nima Arkani-Hamed was my graduate advisor, is a close friend and is the godfather of daughter.
Via Frank Heile.
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