The concept of the "quality" of energy decreasing in the universe is related to the idea of entropy, which is a fundamental principle in physics. Entropy is a measure of the disorder or randomness in a system. According to the second law of thermodynamics, the entropy of an isolated system tends to increase over time.
Energy quality refers to the usefulness or organization of energy within a system. In practical terms, it can be thought of as the ability of energy to do work or perform useful tasks. High-quality energy is concentrated, organized, and available for doing work, while low-quality energy is more dispersed and less able to perform useful tasks.
The degradation of energy quality in the universe is a consequence of the second law of thermodynamics. As energy is transformed and transferred within a system, some of it is inevitably lost or dissipated as waste heat. This process increases the entropy of the system and reduces the availability of high-quality energy.
On a cosmic scale, the universe is continually expanding and evolving. Stars, which are sources of high-quality energy, eventually exhaust their nuclear fuel and undergo processes like stellar death, such as supernovae or white dwarf cooling. As these events occur, energy is radiated away, spreading out and becoming less concentrated and useful. Over vast timescales, the universe is moving towards a state of maximum entropy, where energy is uniformly distributed and no further useful work can be extracted.
It's worth noting that while the quality of energy decreases on a macroscopic scale, energy is conserved according to the law of conservation of energy. The total amount of energy in the universe remains constant, but its availability for useful work diminishes over time due to the increase in entropy.