Semilinear Wave Equation  White Noise
Hello!
I am required to do a paper on the Semilinear Wave Equation as part of a Stochastic Partial Differential Equations seminar.
The problem is, that I've never taken a course on partial differential equations (only ordinary differential equations) or functional analysis.
Now I have the following in front of me:
Let and be predictable random fields
depending on the parameters and . We consider
the initialboundary value problems for a stochastic wave equation
as follows
,

where
My problem is now, that I don't understand how this second order differential was constructed.
What are , , supposed to be here and what has this to do with waves?
Thank you for your time.
If you can pinpoint me to some resources, which will make my life easier in understanding this. I will be very thankful!