What are the main ideas of Harald Helfgott's [proof](http://arxiv.org/abs/1305.2897) that all odd $n \geq 5$ is the sum of 3 primes?



Proof of the weak Goldbach Conjecture
I think this blog post of Terry Tao, as well as the comments following it (including some from Helfgott) answer this question as completely as one could reasonably hope.


<https://terrytao.wordpress.com/2012/05/20/heuristic-limitations-of-the-circle-method/>


