What is Manifolds: Definition and 282 Discussions

In mathematics, a manifold is a topological space that locally resembles Euclidean space near each point. More precisely, an n-dimensional manifold, or n-manifold for short, is a topological space with the property that each point has a neighborhood that is homeomorphic to an open subset of n-dimensional Euclidean space.
One-dimensional manifolds include lines and circles, but not figure eights. Two-dimensional manifolds are also called surfaces. Examples include the plane, the sphere, and the torus, and also the Klein bottle and real projective plane.
The concept of a manifold is central to many parts of geometry and modern mathematical physics because it allows complicated structures to be described in terms of well-understood topological properties of simpler spaces. Manifolds naturally arise as solution sets of systems of equations and as graphs of functions. The concept has applications in computer-graphics and augmented-reality given the need to associate pictures (texture) to coordinates (e.g. CT scans).
Manifolds can be equipped with additional structure. One important class of manifolds are differentiable manifolds; their differentiable structure allows calculus to be done. A Riemannian metric on a manifold allows distances and angles to be measured. Symplectic manifolds serve as the phase spaces in the Hamiltonian formalism of classical mechanics, while four-dimensional Lorentzian manifolds model spacetime in general relativity.
The study of manifolds requires working knowledge of calculus and topology.

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  1. W

    Are Diffeomorphic Manifolds Sharing a Unique Property?

    Could someone please help me with: if N,M are diffeomorphic manifolds, what property do they share that non-diffeomorphic manifolds do not share?. I have thought that if A,B were non-diffeomorphic (with dimA=dimB=n), certain functions (i.e, with their respective coord...
  2. G

    Understand differentiable manifolds

    I am trying to understand differentiable manifolds and have some questions about this topic: We can think of a circle as a 1-dim manifold and make it into a differentiable manifold by defining a suitable atlas. For example two open sets and stereographic projection etc. would be the...
  3. Z

    Spivak Calc on Manifolds, p.85

    Please forgive any stupid mistakes I've made. On p.85, 4-5: If c: [0,1] \rightarrow (R^n)^n is continuous and each (c^1(t),c^2(t),...,c^n(t)) is a basis for R^n , prove that |c^1(0),...,c^n(0)| = |c^1(1),...,c^n(1)| . Maybe I'm missing something obvious, but doesn't c(t) =...
  4. B

    Lie groups as riemann manifolds

    What Lie groups are also Riemann manifolds? thanks
  5. B

    M-Curves: Representations & Properties of C^oo Manifolds

    Let q and q' be sufficiently close points on C^oo manifold M. Then is it true that any C^oo curve c:[a,b]-->M where c(a)=q, c(q)=q' can be represented as c(t)=exp_{q}(u(t)v(t)) where u:[a,b]-->R,v:[a,b]-->TM_{q} and ||v||=1? My question comes from Chapter 9 corollary 16 and 17 of Spivak vol1...
  6. C

    What are Manifolds? Understanding the Continuum in Mathematics and Physics

    what exactly are manifolds? I looked on wikipedia and I am getting the sense that its like n dimensional surface if that makes any sense.
  7. E

    Transformations of Basis Vectors on Manifolds

    Homework Statement I am trying to show that \vec{e'}_a = \frac{\partial x^b}{\partial x'^a} \vec{e}_b where the e's are bases on a manifold and the primes mean a change of coordinates I can get that \frac{\partial x^a}{ \partial x'^b} dx'^b \vec{e}_a = dx'^a \vec{e'}_a from the invariance...
  8. marcus

    NCG 07 (Trieste workshop noncommututative manifolds w. appl. physics)

    http://www.sissa.it/fm/ncg07.html Workshop on Noncommutative Manifolds II Trieste NCG07 October 22-26, 2007 The Department of Mathematics of the University of Trieste and the International School for Advanced Studies (SISSA) organize a workshop on Noncommutative Manifolds. The workshop will...
  9. A

    Problem concerning smooth manifolds

    A={ {{cos x, -sin x},{sin x, cos x}}|x \inR}, show that set A is smooth manifold in space of 2x2 real matrix. What is tangent space in unity matrix? My questions about problem: 1. What is topology here? (Because I need topology to show that this is manifold) 2. In solution they say that...
  10. A

    Solved problems on manifolds: A resource for physics students

    Is there some solved problem book about manifolds? (or where can I find solved problems on manifolds)
  11. MathematicalPhysicist

    Taking a course in calculus on manifolds.

    im thinking of taking in 2008 the second semester a course in analysis of manifolds. now some of the preliminaries although not obligatory, are differnetial geometry and topology, i will not have them at that time, so i think to learn it by my own, will baby rudin and adult rudin books will...
  12. quasar987

    Definition of cross product in Spivak's 'Calculus on Manifolds'

    Homework Statement In Calculus on Manifold pp.83-84, Spivak writes that "if v_1,...,v_{n-1} are vectors in R^n and f:R^n-->R is defined by f(w)=det(v_1,...,v_{n-1},w), then f is an alternating 1-tensor on R^n; therefore there is a unique z in R^n such that <w,z>=f(w) (and this z is denoted v_1...
  13. B

    Learn About Grassmann Manifolds: Intro, Charts, Atlas

    I need to following subjects about GRASSMANN MANIFOLDS,what do I? 1)introduction(together with details) 2)charts,atlas(together with details) 3)depended subjects
  14. quasar987

    Link btw manifolds and space-time

    Fact: Spacetime is a curved pseudo-Riemannian manifold with a metric of signature (-+++). Fact: A manifold is a set together with a topology that is locally homeomorphic to R^n. Question: In the case of space-time, what is the set, what is the topology and what is n?
  15. V

    Linear transition maps on manifolds

    Hi, I have a question. Consider a differentiable manifold. This structure is imposed by requiring differentiability of the transition functions between charts of the atlas. Does requiring on top of that, linearity or affinity of the transition functions, result in any specific extra...
  16. C

    Lie Derivative of Real-Valued Functions and Vectorfields on Manifolds

    Let M be a diff. manifold, X a complete vectorfield on M generating the 1-parameter group of diffeomorphisms \phi_t. If I now define the Lie Derivative of a real-valued function f on M by \mathscr{L}_Xf=\lim_{t\rightarrow 0}\left(\frac{\phi_t^*f-f}{t}\right)=\frac{d}{dt}\phi_{t}^{*}f |_{t=0}...
  17. A

    My Solutions to Tensors and Manifolds

    My Solutions to "Tensors and Manifolds" Textbook Right now I am reading my current favourite book "Tensors and Manifolds with Applications to Relativity" by Wasserman, 1992. I am doing the exercises and typing out my solutions. I would like to share my solutions (with the questions typed out)...
  18. A

    Continous groups and manifolds

    According to my notes on SUSY 'as everyone knows, every continuous group defines a manifold', via \Lambda : G \to \mathcal{M}_{G} \{ g = e^{i\alpha_{a}T^{a}} \} \to \{ \alpha_{a} \} It gives the examples of U(1) having the manifold \mathcal{M}_{U(1)} = S^{1} and SU(2) has...
  19. P

    Spivak calculus on manifolds solutions? (someone asked this b4 and got ignored)

    Does anyone know if there's worked out solution to the problems in spivak's calculus on manifolds? It's awfully easy to get stuck in the problems and for some of them I don't even know where to start... Also, if there isn't any, any good problem and 'SOLUTION' source for analysis on manifolds...
  20. M

    Transforming to curved manifolds

    I know that the Riemann tensor vanishes in a flat space. And no amount of co-ordinate transformations can go from a flat space to a curved space. Does that mean there is no transformation that will go from, say Cartesian 2D, to (\theta,\phi), the co-ordinates usually used for the unit 2-sphere...
  21. R

    Riemannian Manifolds: Metric Structures for Topological Spaces

    A manifold is a topological space which locally looks like R^n. Calculus on a manifold is assured by the existence of smooth coordinate system. A manifold may carry a further structure if it is endowed with a metric tensor. Why further structure? If have sphere or a cylinder I can...
  22. A

    Symmetric Matrices and Manifolds Answer Guide

    (1) If A is an n x n matrix, then prove that (A^T)A (i.e., A transpose multiplied by A) is symmetric. (2) Let S be the set of symmetric n x n matrices. Prove that S is a subspace of M, the set of all n x n matrices. (3) What is the dimension of S? (4) Let the function f : M-->S be defined by...
  23. P

    Smooth function between smooth manifolds

    Hi. I'm a bit stuck with that next question (and that's quite an understatement): Let f:M->N be a continuous map, with M and N smooth manifolds of dimensions m,n correspondingly. Define f*:C(N)->C(M) by f*(g)=g o f. Assume now that f*(C^infty(N)) subset C^infty(M). Then f is...
  24. T

    Supplement to spivak's calc on manifolds

    so i checked out Spivak's calculus on manifolds today, to work on while I'm in colorado this summer. i just finished up this semester with calc3 (multivariable), and I've take matrix theory and linear algebra as well. should I be good to go on this book at this point? I'd like to know since...
  25. K

    Is the Given 4D Manifold Closed?

    1) General question : Let's take a usual line : it's a 1D manifold in 2D space. The line is closed if there are no border points. (circle, aso...) Let suppose a usual surface : it's a 2D manifold enbedded in 3D space. The surface is closed if there are no border line. (sphere, torus...
  26. M

    Exploring the Manifold of Eigenfunctions in Quantum Mechanics

    So the equations of QM give eigenfunctions and eigenvalues. The eigenfunctions form a complete set with which any state is a combination of such. When measuring, the superposition of states collapse to one of the eigenfunctions. And the probability that some state with be measured in a...
  27. MathematicalPhysicist

    Exploring Stratified Manifolds: Insights from Julian Barbour's Research

    hi, i encountered this term in julian barbour webpage and i will like it if someone can tell me more about them?
  28. M

    Number of Calabi-Yau Manifolds in Superstring Theories

    I want to know how many Calabi-Yau manifolds there are in each of the 5 superstring theories. Can you point me in the right direction?
  29. F

    How Do You Structure a Paraboloid as a Smooth Manifold?

    i am trying to solve this problem: Give the paraboloid y_{3}=(y_{1})^2+(y_{2})^2 the structure of a smooth manifold. But i am unsure what it means by structure. Can anyone give me some help here?
  30. M

    World-sheets, manifolds, and coordinate systems

    I'm trying to understand the manifold properties of world-sheets in string theory. I'm told that world sheets are manifolds and that manifolds are locally Euclidean. So I would like to know the characteristics between the space-time coordinates of the world-sheet given as x&mu; verses the 2D...
  31. MathematicalPhysicist

    What are Calabi-Yau Manifolds?

    what are they?
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