since velocity is always based on a frame of reference, can I just change my frame of reference to have different amounts of kinetic energy? Where does that energy come from?
In: Physics
In relativity, energy is forced to be conserved, by requiring the total energy be invariant between frame of reference. Kinetic energy itself can change, but this change will change the mass of the object. Hence the famous Einstein equation: E^2 =m^2 c^4 +p^2 c^2
In Newton’s view of physics, there is absolute frame of reference, so there are no frame of reference problem. In Galileo’s physics, energy is merely a relative number, or in other word, the number itself is meaningless, only the rate of change matter (compare this situation to voltage vs voltage difference). So you can arbitrarily just add any fixed constant to energy, “conserved” just mean it rate of change is 0.
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