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The secret of energy: Why do the laws of physics vary so much at different scales?
In the field of physics, especially theoretical physics, there is a concept called Renormalization Group (RG), which allows us to systematically explore changes in physical systems at different scales. This concept is not limited to microparticle physics, but also extends to many fields such as solid-state physics, fluid mechanics, physical cosmology, and even nanotechnology.
The renormalization group method is a powerful tool that enables systematic analysis of the behavior of physical theories at varying energy scales.
Simply put, when we observe physical processes at different energy scales, the basic force laws change. This change in scale is called scale transformation. The internal structure of a physical theory often exhibits self-similar characteristics as the observation size changes. For example, when we observe an electron with a "magnifying glass", we can find that its properties seem to become more complicated at short distance scales, showing more basic components such as electrons, positron pairs, and photons.
The history of renormalization can be traced back to ancient physical thought, such as the Pythagoreans and Aristotle's considerations of scale in ancient Greece. These ideas revived in the late 19th century and found new life in the renormalization of particle physics. In 1953, Ernst Stukelberg and Andre Pateman first proposed ideas related to RG in the study of quantum electrodynamics, paving the way for subsequent research.
The core of renormalization is that when the scale of observation distance changes, the theory will show its own self-similar properties.
In 1954, Murray Gell-Mann and Francis Lowe tightened the concept of RG in quantum electrodynamics, focusing on the asymptotic form of photon propagators at high energies. They realized that changes in electromagnetic coupling could be derived by simply scaling the structure, further developing a key idea of the normalization reduction. This process not only explains the behavior of elementary particles, but also helps us understand the fundamental forces in the universe.
Renormalization groups are largely derived from renormalization procedures for quantum field variables, which are often required to deal with infinite problems in quantum field theory. For example, in solving the infinity problem of quantum electrodynamics, Richard Feynman, Julian Schwinger, and friends successfully used renormalization of mass and charge to reconcile quantum behavior in the higher momentum range with Long-range observable physical quantities.
The process of renormalization demonstrates the subtle dependence between physical quantities and scales in quantum field theory.
Such thinking further led to the understanding of quantum chromodynamics - a theory involving particle interactions that is now widely accepted. In 1973, scientists discovered that the negative beta function of quantum chromodynamics surprisingly predicted the behavior of coupling constants at high energies. Through continuous research, physicists are becoming more and more aware of the transformation and self-similarity between different scales. The "block spin" renormalization proposed by Kadanoff in 1966 is very useful in teaching. Through this model, physicists can understand how fixed points appear in the long-range behavior of physical systems as the observation scale increases.
To this day, the influence of the renormalization group has not diminished. Whether it is from basic physics or applied physics, renormalization can help researchers better understand complex physical systems and provide a solid foundation for research on quantum gravity, the standard model and related critical phenomena. As scientists conduct in-depth research under this theoretical framework, many unknown phenomena have gradually surfaced.
On our journey to discover the mysteries of physics, we can’t help but ask, as technology advances, how will future discoveries challenge our existing understanding of energy and its behavior?
