We have a field dedicated to observing the physics of atoms in bulk. It is called chemistry. The underpinnings of chemistry in physics came together at the beginning of the 20th century, and we have developed a pretty solid understanding of it since, along with sub-disciplines that focus on specific large systems. If physicists want to get in on the action, there are probably graduate programs that would be happy to have then being their skills in math, optics, subatomic particles, etc to fields in chemistry.