Fiber of spherical tangent bundle












0












$begingroup$


I've been reading a book of tessellations and three-manifolds and it's been said that "the fiber of ST(X) is the 1-sphere and thus ST(X) is a closed 3-manifold", where ST(X) is the spherical tangent bundle of a compact, connected 2-manifold X, that is, the subbundle of TX consisting of vectors of norm 1. Honestly, I don't understand why the assertion between quotations marks is true (why it is a 3-manifold). Could anyone help me?



Many thanks.










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$endgroup$








  • 1




    $begingroup$
    Just out of interest, what book is this?
    $endgroup$
    – Lukas Kofler
    Dec 25 '18 at 23:07






  • 1




    $begingroup$
    Hint: a fiber bundle is locally trivial, and the product of an $n$-dimensional manifold with an $m$-dimensional manifold is an $n+m$-dimensional manifold.
    $endgroup$
    – KReiser
    Dec 25 '18 at 23:16










  • $begingroup$
    The book is Classical Tessellations and Three-Manifolds by José M. Montesinos.
    $endgroup$
    – Rubén Fernández Fuertes
    Dec 25 '18 at 23:24










  • $begingroup$
    Thank you, KReiser!
    $endgroup$
    – Rubén Fernández Fuertes
    Dec 25 '18 at 23:25
















0












$begingroup$


I've been reading a book of tessellations and three-manifolds and it's been said that "the fiber of ST(X) is the 1-sphere and thus ST(X) is a closed 3-manifold", where ST(X) is the spherical tangent bundle of a compact, connected 2-manifold X, that is, the subbundle of TX consisting of vectors of norm 1. Honestly, I don't understand why the assertion between quotations marks is true (why it is a 3-manifold). Could anyone help me?



Many thanks.










share|cite|improve this question











$endgroup$








  • 1




    $begingroup$
    Just out of interest, what book is this?
    $endgroup$
    – Lukas Kofler
    Dec 25 '18 at 23:07






  • 1




    $begingroup$
    Hint: a fiber bundle is locally trivial, and the product of an $n$-dimensional manifold with an $m$-dimensional manifold is an $n+m$-dimensional manifold.
    $endgroup$
    – KReiser
    Dec 25 '18 at 23:16










  • $begingroup$
    The book is Classical Tessellations and Three-Manifolds by José M. Montesinos.
    $endgroup$
    – Rubén Fernández Fuertes
    Dec 25 '18 at 23:24










  • $begingroup$
    Thank you, KReiser!
    $endgroup$
    – Rubén Fernández Fuertes
    Dec 25 '18 at 23:25














0












0








0





$begingroup$


I've been reading a book of tessellations and three-manifolds and it's been said that "the fiber of ST(X) is the 1-sphere and thus ST(X) is a closed 3-manifold", where ST(X) is the spherical tangent bundle of a compact, connected 2-manifold X, that is, the subbundle of TX consisting of vectors of norm 1. Honestly, I don't understand why the assertion between quotations marks is true (why it is a 3-manifold). Could anyone help me?



Many thanks.










share|cite|improve this question











$endgroup$




I've been reading a book of tessellations and three-manifolds and it's been said that "the fiber of ST(X) is the 1-sphere and thus ST(X) is a closed 3-manifold", where ST(X) is the spherical tangent bundle of a compact, connected 2-manifold X, that is, the subbundle of TX consisting of vectors of norm 1. Honestly, I don't understand why the assertion between quotations marks is true (why it is a 3-manifold). Could anyone help me?



Many thanks.







geometry algebraic-topology






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share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Dec 25 '18 at 23:16









KReiser

10k21435




10k21435










asked Dec 25 '18 at 22:56









Rubén Fernández FuertesRubén Fernández Fuertes

1087




1087








  • 1




    $begingroup$
    Just out of interest, what book is this?
    $endgroup$
    – Lukas Kofler
    Dec 25 '18 at 23:07






  • 1




    $begingroup$
    Hint: a fiber bundle is locally trivial, and the product of an $n$-dimensional manifold with an $m$-dimensional manifold is an $n+m$-dimensional manifold.
    $endgroup$
    – KReiser
    Dec 25 '18 at 23:16










  • $begingroup$
    The book is Classical Tessellations and Three-Manifolds by José M. Montesinos.
    $endgroup$
    – Rubén Fernández Fuertes
    Dec 25 '18 at 23:24










  • $begingroup$
    Thank you, KReiser!
    $endgroup$
    – Rubén Fernández Fuertes
    Dec 25 '18 at 23:25














  • 1




    $begingroup$
    Just out of interest, what book is this?
    $endgroup$
    – Lukas Kofler
    Dec 25 '18 at 23:07






  • 1




    $begingroup$
    Hint: a fiber bundle is locally trivial, and the product of an $n$-dimensional manifold with an $m$-dimensional manifold is an $n+m$-dimensional manifold.
    $endgroup$
    – KReiser
    Dec 25 '18 at 23:16










  • $begingroup$
    The book is Classical Tessellations and Three-Manifolds by José M. Montesinos.
    $endgroup$
    – Rubén Fernández Fuertes
    Dec 25 '18 at 23:24










  • $begingroup$
    Thank you, KReiser!
    $endgroup$
    – Rubén Fernández Fuertes
    Dec 25 '18 at 23:25








1




1




$begingroup$
Just out of interest, what book is this?
$endgroup$
– Lukas Kofler
Dec 25 '18 at 23:07




$begingroup$
Just out of interest, what book is this?
$endgroup$
– Lukas Kofler
Dec 25 '18 at 23:07




1




1




$begingroup$
Hint: a fiber bundle is locally trivial, and the product of an $n$-dimensional manifold with an $m$-dimensional manifold is an $n+m$-dimensional manifold.
$endgroup$
– KReiser
Dec 25 '18 at 23:16




$begingroup$
Hint: a fiber bundle is locally trivial, and the product of an $n$-dimensional manifold with an $m$-dimensional manifold is an $n+m$-dimensional manifold.
$endgroup$
– KReiser
Dec 25 '18 at 23:16












$begingroup$
The book is Classical Tessellations and Three-Manifolds by José M. Montesinos.
$endgroup$
– Rubén Fernández Fuertes
Dec 25 '18 at 23:24




$begingroup$
The book is Classical Tessellations and Three-Manifolds by José M. Montesinos.
$endgroup$
– Rubén Fernández Fuertes
Dec 25 '18 at 23:24












$begingroup$
Thank you, KReiser!
$endgroup$
– Rubén Fernández Fuertes
Dec 25 '18 at 23:25




$begingroup$
Thank you, KReiser!
$endgroup$
– Rubén Fernández Fuertes
Dec 25 '18 at 23:25










1 Answer
1






active

oldest

votes


















1












$begingroup$

Fiber bundles $F to E to X$ are locally trivializable, meaning there is an open neighborhood $U$ of any $xin X$ Such that the inverse image of $U$ under the projection is diffeomorphic to $U times F$, where $F$ is the fiber. In this case, we may choose $U$ to be diffeomorphic to an open neighborhood of $mathbb{R}^2$. Since the tangent space $V$ to a point $x in X$ is isomorphic to $mathbb{R}^2$, we have $F cong S^1$. This tells us that $ST(X)$ is a $3$-manifold.



As for why it's closed, since $X$ is compact and $ST(X)to X$ has compact fibers, $ST(X)$ will be compact as well.






share|cite|improve this answer









$endgroup$













  • $begingroup$
    In the first line, what is E?
    $endgroup$
    – Rubén Fernández Fuertes
    Dec 25 '18 at 23:34










  • $begingroup$
    $E$ is the total space of the bundle and $F$ is the fiber. The notation $F to E to X$ is standard notation for a fiber bundle
    $endgroup$
    – leibnewtz
    Dec 26 '18 at 7:13










  • $begingroup$
    Perfect. Many thanks.
    $endgroup$
    – Rubén Fernández Fuertes
    Dec 26 '18 at 17:11












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1












$begingroup$

Fiber bundles $F to E to X$ are locally trivializable, meaning there is an open neighborhood $U$ of any $xin X$ Such that the inverse image of $U$ under the projection is diffeomorphic to $U times F$, where $F$ is the fiber. In this case, we may choose $U$ to be diffeomorphic to an open neighborhood of $mathbb{R}^2$. Since the tangent space $V$ to a point $x in X$ is isomorphic to $mathbb{R}^2$, we have $F cong S^1$. This tells us that $ST(X)$ is a $3$-manifold.



As for why it's closed, since $X$ is compact and $ST(X)to X$ has compact fibers, $ST(X)$ will be compact as well.






share|cite|improve this answer









$endgroup$













  • $begingroup$
    In the first line, what is E?
    $endgroup$
    – Rubén Fernández Fuertes
    Dec 25 '18 at 23:34










  • $begingroup$
    $E$ is the total space of the bundle and $F$ is the fiber. The notation $F to E to X$ is standard notation for a fiber bundle
    $endgroup$
    – leibnewtz
    Dec 26 '18 at 7:13










  • $begingroup$
    Perfect. Many thanks.
    $endgroup$
    – Rubén Fernández Fuertes
    Dec 26 '18 at 17:11
















1












$begingroup$

Fiber bundles $F to E to X$ are locally trivializable, meaning there is an open neighborhood $U$ of any $xin X$ Such that the inverse image of $U$ under the projection is diffeomorphic to $U times F$, where $F$ is the fiber. In this case, we may choose $U$ to be diffeomorphic to an open neighborhood of $mathbb{R}^2$. Since the tangent space $V$ to a point $x in X$ is isomorphic to $mathbb{R}^2$, we have $F cong S^1$. This tells us that $ST(X)$ is a $3$-manifold.



As for why it's closed, since $X$ is compact and $ST(X)to X$ has compact fibers, $ST(X)$ will be compact as well.






share|cite|improve this answer









$endgroup$













  • $begingroup$
    In the first line, what is E?
    $endgroup$
    – Rubén Fernández Fuertes
    Dec 25 '18 at 23:34










  • $begingroup$
    $E$ is the total space of the bundle and $F$ is the fiber. The notation $F to E to X$ is standard notation for a fiber bundle
    $endgroup$
    – leibnewtz
    Dec 26 '18 at 7:13










  • $begingroup$
    Perfect. Many thanks.
    $endgroup$
    – Rubén Fernández Fuertes
    Dec 26 '18 at 17:11














1












1








1





$begingroup$

Fiber bundles $F to E to X$ are locally trivializable, meaning there is an open neighborhood $U$ of any $xin X$ Such that the inverse image of $U$ under the projection is diffeomorphic to $U times F$, where $F$ is the fiber. In this case, we may choose $U$ to be diffeomorphic to an open neighborhood of $mathbb{R}^2$. Since the tangent space $V$ to a point $x in X$ is isomorphic to $mathbb{R}^2$, we have $F cong S^1$. This tells us that $ST(X)$ is a $3$-manifold.



As for why it's closed, since $X$ is compact and $ST(X)to X$ has compact fibers, $ST(X)$ will be compact as well.






share|cite|improve this answer









$endgroup$



Fiber bundles $F to E to X$ are locally trivializable, meaning there is an open neighborhood $U$ of any $xin X$ Such that the inverse image of $U$ under the projection is diffeomorphic to $U times F$, where $F$ is the fiber. In this case, we may choose $U$ to be diffeomorphic to an open neighborhood of $mathbb{R}^2$. Since the tangent space $V$ to a point $x in X$ is isomorphic to $mathbb{R}^2$, we have $F cong S^1$. This tells us that $ST(X)$ is a $3$-manifold.



As for why it's closed, since $X$ is compact and $ST(X)to X$ has compact fibers, $ST(X)$ will be compact as well.







share|cite|improve this answer












share|cite|improve this answer



share|cite|improve this answer










answered Dec 25 '18 at 23:17









leibnewtzleibnewtz

2,6411717




2,6411717












  • $begingroup$
    In the first line, what is E?
    $endgroup$
    – Rubén Fernández Fuertes
    Dec 25 '18 at 23:34










  • $begingroup$
    $E$ is the total space of the bundle and $F$ is the fiber. The notation $F to E to X$ is standard notation for a fiber bundle
    $endgroup$
    – leibnewtz
    Dec 26 '18 at 7:13










  • $begingroup$
    Perfect. Many thanks.
    $endgroup$
    – Rubén Fernández Fuertes
    Dec 26 '18 at 17:11


















  • $begingroup$
    In the first line, what is E?
    $endgroup$
    – Rubén Fernández Fuertes
    Dec 25 '18 at 23:34










  • $begingroup$
    $E$ is the total space of the bundle and $F$ is the fiber. The notation $F to E to X$ is standard notation for a fiber bundle
    $endgroup$
    – leibnewtz
    Dec 26 '18 at 7:13










  • $begingroup$
    Perfect. Many thanks.
    $endgroup$
    – Rubén Fernández Fuertes
    Dec 26 '18 at 17:11
















$begingroup$
In the first line, what is E?
$endgroup$
– Rubén Fernández Fuertes
Dec 25 '18 at 23:34




$begingroup$
In the first line, what is E?
$endgroup$
– Rubén Fernández Fuertes
Dec 25 '18 at 23:34












$begingroup$
$E$ is the total space of the bundle and $F$ is the fiber. The notation $F to E to X$ is standard notation for a fiber bundle
$endgroup$
– leibnewtz
Dec 26 '18 at 7:13




$begingroup$
$E$ is the total space of the bundle and $F$ is the fiber. The notation $F to E to X$ is standard notation for a fiber bundle
$endgroup$
– leibnewtz
Dec 26 '18 at 7:13












$begingroup$
Perfect. Many thanks.
$endgroup$
– Rubén Fernández Fuertes
Dec 26 '18 at 17:11




$begingroup$
Perfect. Many thanks.
$endgroup$
– Rubén Fernández Fuertes
Dec 26 '18 at 17:11


















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