The new physics in everyday life

Mark Buchanan

A. J. Leggett

This brief chapter speculates about the future of physics. It raises the question as to whether, as we progress with the extrapolation of quantum mechanics towards the level of everyday life, we will eventually find that the properties of complex, macroscopic bodies are not, as usually assumed, simply a consequence of those of the microscopic entities composing them, but involve new and currently unforeseeable physical principles.

DOUGLAS M. GINGRICH

At the beginning of the 20th Century new branches of physics were developed to describe two extreme realms of reality: the very small and the very fast. The special theory of relativity was developed around 1905 and describes physical systems traveling at near the speed of light. Likewise, quantum mechanics was developed starting around 1900 to describe systems at the atomic level. Both theories radically transformed our understanding of science and philosophy, and now affect our everyday life.

Phuong Mai Dinh, Jesús Navarro, E. Suraud

Quantum fluids are fluids, indeed. We have seen in the previous chapter what it means from a classical physics point of view. But quantum fluids are by definition ruled by quantum physics, as well. The goal of this chapter is to introduce some key concepts of quantum physics necessary to understand what makes a fluid a quantum one or rather what quantum property makes an ensemble of particles a quantum fluid. We are here precisely at the edge of our basic intuition of quantum physics. Indeed, one usually associates the notion of quantum object to a microscopic nature and it may thus a priori seem paradoxical to link the word quantum to a macroscopic object, such as the notion of fluid. Thinking it over a bit deeper, quantum physics is certainly present at all scales and we are confronted with quantum mechanics through the many electronic devices which have invaded our everyday life. And it actually turns out that, as we will see later on, most of these quantum devices are directly connected to the notion of quantum fluids, the case of electron fluids being certainly the most common one in such devices. Quantum physics has for sure deeply modified our everyday life. But it has also changed our perception of the world, and as we shall see in this chapter, it is precisely this new vision of the world which allows us to understand the concept of quantum fluids underlying so many physical systems.