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Conservation refers to the responsible management and protection of natural resources and ecosystems to prevent their depletion or degradation. It involves sustainable practices aimed at preserving biodiversity, maintaining ecosystem services, and ensuring the long-term well-being of both humanity and the environment.
The total amount of energy in a closed system remains constant according to the law of conservation of energy. Energy can change from one form to another, such as from potential to kinetic or thermal energy, but the total energy within the system remains the same.
To be honest, I was searching "The internal energy of an isolated system is" to get an answer myself. However, in the light that energy is constant, that makes a lot of sense. The internal energy is constant in an isolated system because external factors cannot change what is occurring in such a system. The energy is therefore constant considering equilibrium. Over time, the rate of anything will become stabilized, such as when there is a gas-liquid equilibrium and rate of condensation = rate of vaporization. In short, it's constant because of equilibrium and the fact that outside things have no effect.
It really can't, for all practical purposes. When virtual particle-antiparticle pairs are created, it is broken for a very, very short time (limited by the Uncertainty Principle), but just as in the case of some other interesting physical effects, there is no way this can be used to run an engine without energy input.
Both a wave with long wavelength and a wave with short wavelength can have a lot of energy, or little energy.Specifically in the case of electromagnetic waves, a short wavelength corresponds to high energy - but this is only the energy PER PHOTON. But note that each of such waves usually consists of a lot of photons.