Domain of influence for wave equation in 2 dimensions

In summary, the conversation discusses the existence of solutions for the wave equation in 2 dimensions at later times, specifically when there is an initial disturbance. The solution is represented by an equation involving the initial position, velocity, and a circle domain. The participants question how this solution shows that it extends outwards and why it continues to exist at later times. They also question whether the solution can be negative and why Hyugen's principle fails in 2 dimensions. One participant suggests looking into the Anthropic Principle for further understanding.
  • #1
somethingstra
17
0
Hello, I have some trouble seeing why the solution of the wave equation in 2 dimensions exist at all later times once it passes an initial disturbance...

For example, take a simple case where the initial position is zero, and the initial velocity equals some function inside some circle domain. The solution would be:

[tex]\frac{1}{2\pi }\int \int \frac{\psi (x,y)\partial x\partial y}{\sqrt{t_{o}^{2}-(x-x_{0})^{2}-(y-y_{o})^{2}}}[/tex]

1) Where in that equation tells you that the solutions continues to exist at all later times?
2) If the initial velocity was zero outside the circle domain, why would the solution continue to exist? If we plug in Ψ = 0, wouldn't the solution be zero instead?
3) Can a solution be negative?
 
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  • #2
Maybe I am not being clear. What I just want to know is how this solution shows that it extends outwards at t>0 and why it continues to exist at all later times. In other words, can somebody prove to me why Hyugen's principle fails at dimension 2?
 
Last edited:
  • #3
bump...two days and no answer at all?
 
  • #5
I've read that many times and still do not understand. Can someone explain it from the formula I posted above?
 

1. What is the domain of influence for a wave equation in 2 dimensions?

The domain of influence for a wave equation in 2 dimensions refers to the region in space where the solution to the equation is affected by the initial conditions. It is essentially the area where the wave's behavior is influenced by its surroundings.

2. How is the domain of influence determined for a wave equation in 2 dimensions?

The domain of influence is determined by the speed at which the wave travels and the amount of time it takes for the wave to reach a particular point in space. This can be calculated using the distance formula and the wave's velocity.

3. Does the domain of influence change for different types of waves?

Yes, the domain of influence can vary for different types of waves. For example, the domain of influence for a sound wave in 2 dimensions would be different from the domain of influence for an electromagnetic wave in 2 dimensions. This is because different waves have different velocities and behaviors.

4. How does the shape of the wave affect its domain of influence in 2 dimensions?

The shape of the wave does not directly affect its domain of influence in 2 dimensions. However, the shape of the wave can affect its velocity, which in turn can impact the size and shape of its domain of influence.

5. Can the domain of influence for a wave equation in 2 dimensions be infinite?

No, the domain of influence for a wave equation in 2 dimensions cannot be infinite. This is because the wave's velocity is finite and there will always be a point at which the wave's influence diminishes. However, the domain of influence can be very large depending on the velocity and time frame of the wave.

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