Macroscopic Quantum Mechanics

Quantum Mechanics is the study of the fundamental nature of particles and fields. Normally, regular Newtonian mechanics is all that is necessary to understand the world around us. However, as we start to deal with very small objects, their “quantum” natures become important. Weird and unexpected effects become apparent, as fundamental particles become impossible to locate with any certainty (Heisenberg’s uncertainty principle), and can pass through seemingly impenetrable barriers (quantum leaps and tunneling).

Scientists have repeatedly found quantum mechanics to be an essential and powerful tool in understanding the behavior of particles like electrons and photons. However, certain complications arise in trying to understand how the theory generalizes to involve scales vary far from the scale of electrons in an atom. For example, if we have a massive particle, its quantum behavior may be influenced by its own gravitational field.1) We can expect that the gravitational influence of an electron on itself would be so small as to be negligible.

An interesting possibility arise to observe a truly massive particle operating in the quantum regime with the LIGO instrument. LIGO is an exquisitely precise device used to measure miniscule movements in the positions of a set of mirrors placed 4 kilometers apart. (LIGO is already working, attempting to measure the ripples in spacetime given off by distant black holes and neutron stars.) Basically, LIGO measures motions as small as 10^-16 meters (about 3 tenths of a millionth of a billionth of a foot) of a particle of roughly 10 kilograms—22 pounds. This particle is heavy enough that we might expect its own gravity to be important to its quantum behavior, and the precision of the measurement is great enough that we might be able to see that behavior, if we are clever enough.

Macroscopic Quantum Mechanics is a project pursuing the goal of making these measurements