What is the substance that matter and energy are states of? Since they are transferrable, I assume there is a type of entity that forms the ‘set’ of these two states. However, the only thing that comes to mind for me is ‘immortality’, which is a bit abstract.
Just chiming in to say that I would really like to know the answer, but don’t expect to be able to understand the math…
In a lot of physics, it’s easiest to consider matter a form of energy. So I guess energy is your answer.
It’s sort of like how ice and water are two states of water.
Strings – or nothing!
I agree. You’re really looking for a word not an explanation. What do we call that thing that matter and energy are two manifestations of. I don’t believe we have a word for it other than saying that matter is the name of the form of energy of the interaction of a particle with the Higg’s field (assuming that theory is correct). This is comparable to saying heat is the form of energy measured by the random fluctuations in the constituent molecules.
Coming at it from a GR point of view, I would refer to both as stress-energy. Incidentally, pressure and other sorts of stress (internal forces within a substance or object) are also aspects of the same thing, as is flux of momentum. Immortality has nothing whatsoever to do with anything.
I submit for your consideration the term “stuff”. Matter and energy are both forms of stuff. 
Of course, if that’s not highfalutin enough, I’d go with “energy” or, as Chronos suggested, “stress-energy”.
Matter is frozen energy.
I was thinking about the water analogy myself, but came to the different conclusion that ice, water, and steam are all different states of the element H²O. I think it’s just a case of technically speaking vs. generally speaking.
My thought behind the immortality idea was my understanding that matter and energy cannot ever be destroyed, only converted into one another…that’s the connection. Perhaps it’s just an attribute of the overriding substance.
“Mass–energy” seems to be used in this fashion sometimes. Like “spacetime” means both space and time considered as a single phenomenon.
But there are other things that can never be destroyed. Momentum, for example.
“The dreams that stuff is made from.”
that would be bacon.
Baggins! We hates it, we hates it, we hates it for ever!
Matter is just a generic term for stuff.
Mass and energy, on the other hand, are not things, they’re properties of a system. Mass is equal to the energy of a system that can’t be transformed away, but this does not mean that mass is energy.
And no matter how many times you may read or hear it mass cannot be transformed into energy and in fact both are conserved.
They are both manifestations of the graviniferous aether.
Edit: never mind, you’re right. Never thought about it that way
Please believe me when I say that I’m not doubting you but could you explain this to a non-physics guy like myself? I thought that the sun converted mass into energy. I also thought that Einstein’s famous equation said that they were indeed the same thing times a constant.
Didn’t you forget to mention phlogiston as the transforming agent?