Being one of the oldest disciplines of science, field of Physics has enjoyed enormous success employing the philosophy of “Reduction”. That is, by dissecting systems of interest into interacting smaller components, simple universal physical laws can be established to account for the richer behavior of the entire systems. This reduction approach has guided the development of almost all areas in physics, including statistical mechanics, electrodynamics, atomic physics, nuclear physics, particle physics, and condensed matter physics. However, as one dig deeper into the hole and the building blocks becomes smaller and smaller, the number of small units and more importantly the size of the Hilbert space starts to grow out of control. The predictive power or the relevance of the fundamental laws start to become questionable. This Chalk Talk will introduce a new philosophy called “Emergence” introduced into the field of quantum many-body problem about 50 years ago. The key concept is that physical laws for a large number of elements is actually not fixed. Instead, as the energy scale reduces into a more relevance one similar to our observations, the physical laws themselves evolve and generate the complex physical behaviors. A few examples will be mentioned in this talk, followed by a brief introduction of my group’s development of “emergent Bose liquid” theory for strongly correlated materials.
1. Why do students behave differently at home, at school, and during a date?
2. Why are there insulators? Why can’t electron flow freely in solids?
3. What fundamental force dominates the atomic physics? Do we need the knowledge of other forces for such systems? If not, why not?
4. If we already know the dominant physics of atomic physics, why can’t we understand, predict and design new materials that give us the improved properties?
Wei Ku T. D. Lee Professor
Room 204, Building 6 of Science Buildings