Long Time No See, Little Ox (The Grand Finale)

"Another approach"

Hearing what Xu Yun had said,

Zhou Guangzhao, Xue Qikun, and the others in the audience showed little change in expression, though a hint of thoughtfulness crossed their faces.

Just as Xu Yun had said,

just as mentioning Little Ox inevitably brought up universal gravitation, any discussion of superconductivity inevitably had to mention BCS theory.

In the original timeline,

ever since Onnes first discovered superconductivity in 1911, people had believed that aside from having zero electrical resistance, superconducting materials had the same properties as ordinary materials.

However, the discovery in 1933 that superconductors were perfectly diamagnetic shattered that assumption. This perfect diamagnetism was also known as the Meissner effect.

By 1935,

the London brothers had developed the London equation, linking the current flowing through a superconductor to the electromagnetic fields inside and around it, thereby constructing a phenomenological theory of superconductors' electromagnetic properties.

The theory predicted the existence of an electromagnetic penetration depth, which was experimentally confirmed in 1939.

Then, in 1950, physicists discovered that mercury isotopes with lower atomic masses became superconducting at slightly higher temperatures,

indicating that any theory of superconductivity had to take into account the influence of lattice vibrations on the free electrons in a crystal. This phenomenon became known as the "isotope effect" of superconductivity.

Three more years passed.

By analyzing the thermal conductivity of superconductors, physicists realized that the energy distribution of free electrons in a superconductor was not uniform, but instead had an energy gap.

However, all these theories merely described the relationships among observed experimental phenomena. They did not explain those phenomena from the perspective of the fundamental laws of physics.

For nearly fifty years after Onnes discovered superconductivity, theoretical physicists had failed to develop a fundamental theory of the phenomenon.

Until

1957.

That year, three American physicists—Bardeen, Cooper, and