I should have said Kinetic energy in my OP as opposed to simply energy. Apologies.
Fundamental as in one superseeds the other.
i.e. Momentum is always conserved within a closed system but KE is not. Why is this in terms of space and time invariance.
How does that relate to time...
Can someone explain this please.
From what I understand momentum is often the more fundamental as it is spatially invariant, whereas energy is time invariant and as more real world cases fall into the former category momentum is often more fundamental.
What is meant by spatial invariance...