Another camp claims that superposition shows us that potential realities matter just as much as the single, fully manifested one we experience. But what collapses the potential electrons in their two locations into the one electron we actually see? According to this interpretation, it is the very act of looking; the measurement process collapses an ethereal world of potentials into the one real world we experience.

And a third major camp argues that particles can be two places at once only because the universe itself splits into parallel realities at the moment of measurement, one universe for each particle location — and thus an infinite number of ever splitting parallel versions of the universe (and us) are all evolving alongside one another.

These fundamental questions might have lived forever at the intersection of physics and philosophy. Then, in the 1980s, a steady advance of low-cost, high-precision lasers and other “quantum optical” technologies began to appear. With these new devices, researchers, including this year’s Nobel laureates, David J. Wineland and Serge Haroche, could trap and subtly manipulate individual atoms or light particles. Such exquisite control of the nano-world allowed them to design subtle experiments probing the meaning of quantum weirdness.

Soon at least one interpretation, the most common sense version of hidden variables, was completely ruled out.

At the same time new and even more exciting possibilities opened up as scientists began thinking of quantum physics in terms of information, rather than just matter — in other words, asking if physics fundamentally tells us more about our interaction with the world (i.e., our information) than the nature of the world by itself (i.e., matter). And so the field of quantum information theory was born, with very real new possibilities in the very real world of technology.

What does this all mean in practice? Take one area where quantum information theory holds promise, that of quantum computing.

Classical computers use “bits” of information that can be either 0 or 1. But quantum-information technologies let scientists consider “qubits,” quantum bits of information that are both 0 and 1 at the same time. Logic circuits, made of qubits directly harnessing the weirdness of superpositions, allow a quantum computer to calculate vastly faster than anything existing today. A quantum machine using no more than 300 qubits would be a million, trillion, trillion, trillion times faster than the most modern supercomputer.