It is well known that the wave equation agrees with special relativity. So, my question is: it is possible to derive the Lorentz transforms from the equation?
First, I started by assuming a linear transformation of the form: $$ t'= \alpha x + \beta t \\ \; \\ x' = \gamma x + \delta t $$ The wave equation in the S frame is: $$ \frac{1}{c^2}\frac{\partial^2 \psi}{ \partial t^2} = \frac{\partial^2 \psi}{ \partial x^2} $$ The wave equation in the S' frame should be: $$ \frac{1}{c^2}\frac{\partial^2 \psi}{ \partial t'^2} = \frac{\partial^2 \psi}{ \partial x'^2} $$ Applying the chain rule and a change of variables, we get the following: $$ \frac{\partial^2 \psi}{ \partial t^2} \left [ \left ( \frac{1}{c} \frac{\partial t}{ \partial t'} \right ) ^2 - \left (\frac{ \partial t}{ \partial x'} \right ) ^2 \right ] + \frac{\partial^2 \psi}{ \partial t \partial x} \left [ \frac{1}{c^2} \frac{\partial t}{ \partial t'} \frac{\partial x}{ \partial t'} - \frac{ \partial t}{ \partial x'}\frac{ \partial x}{ \partial x'} \right ] + \frac{\partial^2 \psi}{ \partial x^2} \left [ \left ( \frac{1}{c} \frac{\partial x}{ \partial t'} \right ) ^2 - \left (\frac{ \partial x}{ \partial x'} \right ) ^2 \right ] = 0 $$ So we conclude that: $$ \left ( \frac{1}{c} \frac{\partial t}{ \partial t'} \right ) ^2 - \left (\frac{ \partial t}{ \partial x'} \right )^2 = \frac{1}{c^2} \\ $$ $$ \frac{1}{c^2} \frac{\partial t}{ \partial t'} \frac{\partial x}{ \partial t'} - \frac{ \partial t}{ \partial x'}\frac{ \partial x}{ \partial x'} = 0 \\ $$ $$ \left ( \frac{1}{c} \frac{\partial x}{ \partial t'} \right ) ^2 - \left (\frac{ \partial x}{ \partial x'} \right )^2 = -1 \\ $$ But now I'm stuck, how should I continue? Is this line of reasoning right? Any mistake that I made?