Sonic relativity and the observers who hear its call

Nick Menicucci, RMIT University

It is well known that sound waves in a medium are sonically relativistic. That is, they are excitations of a relativistic field modes with c = speed of sound. This sonic relativity governs their motion despite being fully describable using nonrelativistic laboratory physics. As such, they serve as an important analogue for curved-spacetime physics. It is also well known -- although perhaps underappreciated -- that the apparent paradox of general covariance is only resolved when one takes into account the experiences of actual observers. I will discuss, therefore, an important question: what type of "observer" naturally experiences this sonic relativity, and how can they inform our understanding of models of analogue and emergent gravity?

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