How can the method of spherical means be used to prove uniqueness of the wave equation?











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I heard that the method of spherical means can be used to prove uniqueness of the wave equation solution for the initial value problem of a wave at time $0$ and velocity $0$. I've found almost no PDFs about this method. The only good one is this, however it does not prove unicity.



I believe the proof is simple, but it's not something I'd come with because I don't have the intuition on why this method works.










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    A detailed exposition of the wave equation in $mathbb{R}^n$ can be found in Evan's PDE book. He uses the same method to derive Kirchhoff's formula (for even and odd $n$. I don't necessarily think its traditional to prove uniqueness via those means, because of the efficiency of the energy method to do so.
    – DaveNine
    Nov 20 at 9:43










  • For the energy method, we suppose $$e(t) = int_U w_t^2(x,t)+|Dw(x,t)|^2dx$$ where $w = u - bar{u}$ is the difference between two solutions to the initial value problem for the wave equation, then show that $e(t) = 0$.
    – DaveNine
    Nov 20 at 9:46

















up vote
1
down vote

favorite
1












I heard that the method of spherical means can be used to prove uniqueness of the wave equation solution for the initial value problem of a wave at time $0$ and velocity $0$. I've found almost no PDFs about this method. The only good one is this, however it does not prove unicity.



I believe the proof is simple, but it's not something I'd come with because I don't have the intuition on why this method works.










share|cite|improve this question


















  • 1




    A detailed exposition of the wave equation in $mathbb{R}^n$ can be found in Evan's PDE book. He uses the same method to derive Kirchhoff's formula (for even and odd $n$. I don't necessarily think its traditional to prove uniqueness via those means, because of the efficiency of the energy method to do so.
    – DaveNine
    Nov 20 at 9:43










  • For the energy method, we suppose $$e(t) = int_U w_t^2(x,t)+|Dw(x,t)|^2dx$$ where $w = u - bar{u}$ is the difference between two solutions to the initial value problem for the wave equation, then show that $e(t) = 0$.
    – DaveNine
    Nov 20 at 9:46















up vote
1
down vote

favorite
1









up vote
1
down vote

favorite
1






1





I heard that the method of spherical means can be used to prove uniqueness of the wave equation solution for the initial value problem of a wave at time $0$ and velocity $0$. I've found almost no PDFs about this method. The only good one is this, however it does not prove unicity.



I believe the proof is simple, but it's not something I'd come with because I don't have the intuition on why this method works.










share|cite|improve this question













I heard that the method of spherical means can be used to prove uniqueness of the wave equation solution for the initial value problem of a wave at time $0$ and velocity $0$. I've found almost no PDFs about this method. The only good one is this, however it does not prove unicity.



I believe the proof is simple, but it's not something I'd come with because I don't have the intuition on why this method works.







real-analysis pde wave-equation






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asked Nov 20 at 2:03









Lucas Zanella

86411330




86411330








  • 1




    A detailed exposition of the wave equation in $mathbb{R}^n$ can be found in Evan's PDE book. He uses the same method to derive Kirchhoff's formula (for even and odd $n$. I don't necessarily think its traditional to prove uniqueness via those means, because of the efficiency of the energy method to do so.
    – DaveNine
    Nov 20 at 9:43










  • For the energy method, we suppose $$e(t) = int_U w_t^2(x,t)+|Dw(x,t)|^2dx$$ where $w = u - bar{u}$ is the difference between two solutions to the initial value problem for the wave equation, then show that $e(t) = 0$.
    – DaveNine
    Nov 20 at 9:46
















  • 1




    A detailed exposition of the wave equation in $mathbb{R}^n$ can be found in Evan's PDE book. He uses the same method to derive Kirchhoff's formula (for even and odd $n$. I don't necessarily think its traditional to prove uniqueness via those means, because of the efficiency of the energy method to do so.
    – DaveNine
    Nov 20 at 9:43










  • For the energy method, we suppose $$e(t) = int_U w_t^2(x,t)+|Dw(x,t)|^2dx$$ where $w = u - bar{u}$ is the difference between two solutions to the initial value problem for the wave equation, then show that $e(t) = 0$.
    – DaveNine
    Nov 20 at 9:46










1




1




A detailed exposition of the wave equation in $mathbb{R}^n$ can be found in Evan's PDE book. He uses the same method to derive Kirchhoff's formula (for even and odd $n$. I don't necessarily think its traditional to prove uniqueness via those means, because of the efficiency of the energy method to do so.
– DaveNine
Nov 20 at 9:43




A detailed exposition of the wave equation in $mathbb{R}^n$ can be found in Evan's PDE book. He uses the same method to derive Kirchhoff's formula (for even and odd $n$. I don't necessarily think its traditional to prove uniqueness via those means, because of the efficiency of the energy method to do so.
– DaveNine
Nov 20 at 9:43












For the energy method, we suppose $$e(t) = int_U w_t^2(x,t)+|Dw(x,t)|^2dx$$ where $w = u - bar{u}$ is the difference between two solutions to the initial value problem for the wave equation, then show that $e(t) = 0$.
– DaveNine
Nov 20 at 9:46






For the energy method, we suppose $$e(t) = int_U w_t^2(x,t)+|Dw(x,t)|^2dx$$ where $w = u - bar{u}$ is the difference between two solutions to the initial value problem for the wave equation, then show that $e(t) = 0$.
– DaveNine
Nov 20 at 9:46

















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