Eleten Co., Ltd.

When we divide matter and make it infinitesimally small, where do we end up? This worldview of matter, as represented by particle physics, is called the element reductionist approach, and it supports one aspect of the success of physics. If these are challenges to the "infinitely small," then condensed matter physics can be said to be a challenge to the "infinitely large." Solid matter contains about Avogadro's number (1023) of electrons, and it is impossible and meaningless to solve the same number of Schrödinger equations to understand the behavior of all electrons. In condensed matter physics, the function of matter is deductively understood through understanding the behavior of electrons as a multi-particle system. Anderson (P. Anderson) clearly expressed this approach to the material world with the phrase "More is different." There is a "hierarchy" in the material world. In order to understand nature over a wide range of scales in both length and energy, it is necessary to construct physics according to the hierarchy. For example, electrons in solids behave according to the symmetry of crystals, and the physical laws are significantly different from those of electrons as elementary particles. Nevertheless, "infinitely small" and "infinitely many" are not opposing concepts in physics. Although the approaches are different, they are part of the same tool, physics.