Final answer:
Einstein's theory of relativity reconciles differences in energy measurements across inertial frames by refining the definition of energy to include relativistic factors, thus upholding the law of conservation of energy universally.
Step-by-step explanation:
Understanding Energy in Relativity
The observation that energy is not Lorentz invariant because it depends on the state of motion leads to a question about the uniformity of physics laws in different inertial frames. This apparent paradox is resolved in Einstein's theory of relativity, where energy's definition is refined to ensure conservation of energy across all frames. Despite different inertial frames measuring different energies, the law of conservation of energy remains unbroken because energy, including mass-energy equivalence, is adjusted to reflect relativistic factors. Relativistic mechanics reveals that several fundamental quantities which are conserved, such as energy and momentum, are related in ways no longer bound by classical physics notions. This holds profound implications for our understanding of the Universe and is validated by experimental evidence.
Relativistic energy includes a factor that accounts for velocity: when an object moves with velocity u, its relativistic energy is given by E = ymc², where y is the Lorentz factor. Einstein's first postulate of relativity confirms that the laws of physics, including the law of conservation of energy, are the same in every inertial frame and there is no preference for any inertial frame as one of 'absolute rest'.