Superconductivity is a state of matter where electrons can flow without

resistance and where magnetic fields are expelled. It was discovered

serendipitously more than a hundred years ago. Today, superconductors

are essential components of medical imaging devices as well as high

energy particles accelerators.

Understanding this phenomena was one of the greatest intellectual

challenges of the twentieth century. A dramatic advance was provided by

the BCS (Bardeen Cooper Schrieffer) theory 45 years after. It posits that

superconductivity is the result of macroscopic condensation of electron

pairs, which are held together by the vibrations of the lattice. The condensate

is a macroscopic quantum objects and its rigidity accounts for its

striking macroscopic properties.

The BCS theory was so successful that by the early 70’s superconductivity

was considered a completely understood subject with the maximum

achievable critical temperature having been reached experimentally

around 30K. In the late 80’s this field of research took a dramatically turn

with the discovery of new ceramic compounds which superconduct at

temperatures as high as 160 K. These materials, cannot be described by

straightforward extensions of the BCS theory. Scientists are still working

on finding new explanations for these materials and we will describe the

challenge they pose. The quest for room temperature superconductivity

thus continues. A breakthrough in this field would have unimaginable

consequences, changing the way we transmit electricity from its

generation to its consumption to the way we design computers.