Energy in physics feels analogous to money in economics. Is a manmade medium of exchange used for convenience. It is the exchange medium between measureable physical states/things.
Is energy is real in the same way money is? An incredibly useful accounting trick that is used so frequently it feels fundamental, but really it’s just a mathmatical convenience?
Small aside: From this perspective ‘conservatipn of energy’ is a redundant statement. Of course energy must be conserved or else the equations are wrong. The definition of energy is it’s conservation.
Sound is just a pressure wave propogating through any compressible medium, right? Though I think we are a bit inconsistent in how we use it. E.g. Almost no one calls the seismic waves from an earthquake a “sound”.
yeah, human language can be a bit inconsistent/imprecise at times. That is why all tech and engineering have their own language: maths; where consistent and precise descriptions are possible.