The paper by Juan Maldacena explores the relationship between superconformal field theories (SCFTs) and supergravity in the large N limit. It shows that certain SCFTs in various dimensions include a sector describing supergravity on Anti-de Sitter (AdS) spacetimes, spheres, and other compact manifolds. This is demonstrated by considering branes in M/string theory and taking a low energy limit where the field theory on the brane decouples from the bulk. The enhanced supersymmetries of the near horizon geometry correspond to the extra supersymmetry generators in the superconformal group. The $ \mathcal{N}=4 $ super-Yang-Mills theory in 3+1 dimensions at the conformal point is shown to contain strings, which are IIB strings. The paper conjectures that compactifications of M/string theory on AdS spacetimes are dual to various conformal field theories, leading to a new proposal for M-theory. The paper discusses several cases, including D3 branes, M5 branes, M2 branes, and the D1+D5 system. In each case, the large N limit of the field theory is shown to correspond to a supergravity solution on an AdS space times a compact manifold. The supersymmetries of both theories agree, with the superconformal group having twice the number of supersymmetries of the super-Poincare group. The paper also discusses the implications of these results for the understanding of black holes, the behavior of supergravity solutions, and the relationship between field theories and string theory. The paper concludes that the large N limit of certain field theories includes supergravity on AdS spacetimes, and that this provides a new perspective on the relationship between field theories and string theory. It also suggests that the large N limit of field theories can be used to define M-theory, and that this approach can be extended to include five non-compact dimensions. The paper highlights the importance of supersymmetry in these dualities and the role of the AdS/CFT correspondence in understanding the behavior of strongly coupled field theories.The paper by Juan Maldacena explores the relationship between superconformal field theories (SCFTs) and supergravity in the large N limit. It shows that certain SCFTs in various dimensions include a sector describing supergravity on Anti-de Sitter (AdS) spacetimes, spheres, and other compact manifolds. This is demonstrated by considering branes in M/string theory and taking a low energy limit where the field theory on the brane decouples from the bulk. The enhanced supersymmetries of the near horizon geometry correspond to the extra supersymmetry generators in the superconformal group. The $ \mathcal{N}=4 $ super-Yang-Mills theory in 3+1 dimensions at the conformal point is shown to contain strings, which are IIB strings. The paper conjectures that compactifications of M/string theory on AdS spacetimes are dual to various conformal field theories, leading to a new proposal for M-theory. The paper discusses several cases, including D3 branes, M5 branes, M2 branes, and the D1+D5 system. In each case, the large N limit of the field theory is shown to correspond to a supergravity solution on an AdS space times a compact manifold. The supersymmetries of both theories agree, with the superconformal group having twice the number of supersymmetries of the super-Poincare group. The paper also discusses the implications of these results for the understanding of black holes, the behavior of supergravity solutions, and the relationship between field theories and string theory. The paper concludes that the large N limit of certain field theories includes supergravity on AdS spacetimes, and that this provides a new perspective on the relationship between field theories and string theory. It also suggests that the large N limit of field theories can be used to define M-theory, and that this approach can be extended to include five non-compact dimensions. The paper highlights the importance of supersymmetry in these dualities and the role of the AdS/CFT correspondence in understanding the behavior of strongly coupled field theories.