What is Geometric: Definition and 808 Discussions

Geometry (from the Ancient Greek: γεωμετρία; geo- "earth", -metron "measurement") is, with arithmetic, one of the oldest branches of mathematics. It is concerned with properties of space that are related with distance, shape, size, and relative position of figures. A mathematician who works in the field of geometry is called a geometer.
Until the 19th century, geometry was almost exclusively devoted to Euclidean geometry, which includes the notions of point, line, plane, distance, angle, surface, and curve, as fundamental concepts.During the 19th century several discoveries enlarged dramatically the scope of geometry. One of the oldest such discoveries is Gauss' Theorema Egregium ("remarkable theorem") that asserts roughly that the Gaussian curvature of a surface is independent from any specific embedding in an Euclidean space. This implies that surfaces can be studied intrinsically, that is as stand alone spaces, and has been expanded into the theory of manifolds and Riemannian geometry.
Later in the 19th century, it appeared that geometries without the parallel postulate (non-Euclidean geometries) can be developed without introducing any contradiction. The geometry that underlies general relativity is a famous application of non-Euclidean geometry.
Since then, the scope of geometry has been greatly expanded, and the field has been split in many subfields that depend on the underlying methods—differential geometry, algebraic geometry, computational geometry, algebraic topology, discrete geometry (also known as combinatorial geometry), etc.—or on the properties of Euclidean spaces that are disregarded—projective geometry that consider only alignment of points but not distance and parallelism, affine geometry that omits the concept of angle and distance, finite geometry that omits continuity, etc.
Originally developed to model the physical world, geometry has applications in almost all sciences, and also in art, architecture, and other activities that are related to graphics. Geometry also has applications in areas of mathematics that are apparently unrelated. For example, methods of algebraic geometry are fundamental in Wiles's proof of Fermat's Last Theorem, a problem that was stated in terms of elementary arithmetic, and remained unsolved for several centuries.

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    Line Integral Interpretations: Physical and Geometric Uses

    I understand that an example of a physical interpretation of the line integral of a scalar function with respect to arc length \int_C f(x,y,z)ds might be the total mass of a wire where f describes the linear density of the wire. But can anybody give an example of a physical or geometric...
  2. S

    Can You Plot the Parametrization for 3D Geometric Algebra?

    Consider 3D geometric algebra. Let all points on a line be given by the parametrization x=tu+y, in which the parameter runs from minus infinity to plus infinity. a. Show that for all points on the line we have x(wedge)u=y(wedge)u. b. Show that the vector d pointing from the...
  3. S

    Geometric Algebra: Explaining Commutators on Tri-Vectors

    can anyone explain how commutators act on tri-vectors (in orthonormal conditions)? on bi-vectors i know that it ends up to be a bivector again, but with tri-vectors it vanishes if its lineraly dependent. what about the case if its not linearly dependent, does that mean it remains a...
  4. H

    Geometric mechanisms of non-gravitational forces?

    Just wondering... so the conception is that gravity is not really a "force" but rather the consequence of shortest-path motion through curved geometry. Are there analogues for the other forces? I know gravity is not yet theoretically unified with the other forces. But is there nonetheless some...
  5. A

    Geometric Sequences and Logarithms

    I'm having trouble with these type of probles (where a negative log comes up): (All of this is solving without sigma notation) Find the number of terms in these geometric sequences and the sum of the numbers. 11, -22, 44,...,704 I know that a1 = 11, r = -2, and an = 704, so I did...
  6. A

    Geometric Sequences and Series

    I'm trying to get an A in honors AlgII/Trig and it is impossible, but I won't give up, so I have a few questions. I'm not sure how to find the first two terms of a sequence (I got a few right, but most wrong and I don't know what's wrong). One of the problems is: a5 = 20; a8 = 4/25. I set...
  7. Loren Booda

    How to Solve for the Value of B in a Geometric Series

    Can you solve analytically [oo] [pi] (n)1/n n=1 or [oo] [pi] (n!)1/n! n=1 or [oo] [sum] (1/n)n n=1 or [oo] [sum] (1/n!)n! n=1 ?
  8. Loren Booda

    N-dimensional geometric partitioning

    Given n+1 points in n-dimensional Euclidean space, how many polytopes (generalizations of polygons of n to as few as 2 dimensions) may be defined by the representation of each point as a possible vertex?
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