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.
It’s as I said - just because someone (or some species) doesn’t recognize this pattern, doesn’t mean the pattern doesn’t exist.
If some other alien race found a new system of physics that we were unaware of, that does not necessarily invalidate our laws of physics, just as ours would not invalidate theirs. Say, for example, in their system of physics, some arbitrary measurement that we’ll call “azupo” is equivalent to another measurement that we’ll call “bamu”, and this equation is called the “conservation of qugok”, that does not mean that qugok does not exist.
Clearly this equation is true (and therefore qugok is a real concept), otherwise the aliens wouldn’t be able to fly across the galaxy to meet with us humans. Is qugok an innate property of the universe? Most probably not, but we never claimed that qugok (or energy, for that matter) is innate. All this means is just that we never noticed the qugok pattern, and therefore we never gave a name to it. But the qugok pattern is and has always been real.
To put to bluntly: saying that something is arbitrary is not the same as saying that it doesn’t exist. We arbitrarily define the color red, but I hope you won’t argue that the color red doesn’t exist. (Even an alien who can’t see the color red would at least acknowledge that photons can have different wavelengths and that “human red” simply refers to that silly wavelength of light)
Yup, we are in agreement, though I might have missphrased my comments to imply that one shouldn’t believe in energy
To that end, there is a quote from Dumbledore on one of the Harry Potter films (don’t know which one) where he says: “of course this is in your head Harry, but does it make this less real?”