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pcr
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How would one parameterize the three-sphere? Would three angles work: latitude, longitude and something?
pcr said:How would one parameterize the three-sphere? Would three angles work: latitude, longitude and something?
Thank you this was very helpful!jedishrfu said:Wikipedia has an article on it:
https://en.m.wikipedia.org/wiki/3-sphere
You need a 4th coordinate as to whether its an angle or some fixed axis is based on the coordinate system chosen.
A 3D analogue would be spherical vs cylindrical coordinates. One has two angles and the other just one but both have coordinate values to describe a point in 3D space.
https://plus.maths.org/content/richard-elwes
jedishrfu said:Humorously you could call the 4th coordinate:
Fortitude
Something you might need when studying higher dimensioned geometries.
fresh_42 said:The ##3-##sphere (with radius ##1##) is a three dimensional analytic manifold. Two possible ways of looking at it are
$$\mathbb{S}^3 \simeq U(1,\mathbb{H}) \cong SU(2,\mathbb{C})$$
There are others, but I find these convenient. This means you can look at points of ##\mathbb{S}^3## as unit quaternions or as unitary complex matrices with determinant one. Of course you can always use polar coordinates ##(\varphi , \theta , \phi)## or Cartesian coordinates
$$
x_1=\cos \varphi \sin \theta \sin \phi \\
x_2=\sin \varphi \sin \theta \sin \phi \\
x_3=\cos \theta \sin \phi \\
x_4=\cos \phi
$$
If you want to look at it as an isometry group of a four dimensional Euclidean space, then ##\mathbb{S}^3\simeq SO(4,\mathbb{R})/SO(3,\mathbb{R})## would be useful.
Thank you, that was helpfulstevendaryl said:Well, you can describe it using four coordinates [itex]X[/itex], [itex]Y[/itex], [itex]Z[/itex] and [itex]W[/itex] with the constraint [itex]X^2 + Y^2 + Z^2 + W^2 = R^2[/itex]. You can parametrize it in terms of angles like this:
[itex]W = R cos(\psi)[/itex]
[itex]Z = R sin(\psi)cos(\theta)[/itex]
[itex]X = R sin(\psi)sin(\theta)cos(\phi)[/itex]
[itex]Y = R sin(\psi)sin(\theta)sin(\phi)[/itex]
Thank you, that was helpful!fresh_42 said:The ##3-##sphere (with radius ##1##) is a three dimensional analytic manifold. Two possible ways of looking at it are
$$\mathbb{S}^3 \simeq U(1,\mathbb{H}) \cong SU(2,\mathbb{C})$$
There are others, but I find these convenient. This means you can look at points of ##\mathbb{S}^3## as unit quaternions or as unitary complex matrices with determinant one. Of course you can always use polar coordinates ##(\varphi , \theta , \phi)## or Cartesian coordinates
$$
x_1=\cos \varphi \sin \theta \sin \phi \\
x_2=\sin \varphi \sin \theta \sin \phi \\
x_3=\cos \theta \sin \phi \\
x_4=\cos \phi
$$
If you want to look at it as an isometry group of a four dimensional Euclidean space, then ##\mathbb{S}^3\simeq SO(4,\mathbb{R})/SO(3,\mathbb{R})## would be useful.
Thank you, that was helpful!pcr said:Thank you this was very helpful!
The stereographic projection still works, so two and one pole which maps to the origin and the other one to infinity.pcr said:Hello again. Today I would like to ask how many coordinate patches is takes to cover S3? And how many poles are there on a three sphere, if that makes sense?
The 3-sphere, also known as the 3-dimensional sphere, is a geometric object that is one higher dimension than a traditional sphere. It is defined as the set of all points in 4-dimensional space that are equidistant from a fixed point.
Parameterizing the 3-sphere allows us to express points on this curved surface using a set of three coordinates or angles. This makes it easier to work with and understand geometric properties of the 3-sphere, such as distance and curvature.
The three angles used to parameterize the 3-sphere are longitude, latitude, and azimuth. These angles represent the position of a point on the 3-sphere in relation to a fixed point.
The 3-sphere is different from a traditional sphere in that it exists in 4-dimensional space, while a traditional sphere exists in 3-dimensional space. This means that the 3-sphere has an extra dimension, making it a more complex object to study and understand.
Parameterizing the 3-sphere has many applications in fields such as mathematics, physics, and computer graphics. It is used to understand the geometry of higher-dimensional spaces, to study the properties of curved surfaces, and to create 3D models and animations. It also has applications in cosmology and the study of the universe.