You can actually map out exactly what's inside an object just by listening to the way sound hits its surface.
arXiv · March 17, 2026 · 2603.14194
The Takeaway
Determining what is inside a solid object without cutting it open is a major challenge in engineering and medical imaging. This proof shows that for certain types of sound waves, the 'echoes' measured at the boundary contain enough information to map the hidden internal physics of the entire object with total precision.
From the abstract
We consider inverse boundary value problems for the Jordan-Moore-Gibson-Thompson (JMGT) equation in nonlinear acoustics with quadratic nonlinearities of Kuznetsov-type and Westervelt-type. We show that the associated boundary Dirichlet-to-Neumann map uniquely determines the nonlinear coefficients $\beta$ in the Westervelt-type model, and the pair $(\beta,\kappa)$ in the Kuznetsov-type model, provided that the observation time is greater than the maximal boundary-to-boundary geodesic travel time.