Preface
Today, MRI systems with superconducting magnets are commonly used in hospitals,
and commercial superconducting linear maglev trains that connect Tokyo and Nagoya
in Japan in 40 min are scheduled to start in 2027. Thus, superconductivity has become
well-known. In addition, it is known by people who are interested in our global
environmental problems that the introduction of superconducting instruments and
power cables has great potential to contribute to suppression of CO 2 emissions.
Superconductivity is a peculiar phenomenon in which electrical resistance disappears when a superconducting material is cooled down to very low temperatures.
Thus, it has been investigated for a long time in solid-state physics, and many scientists have received Nobel prizes for work based on superconductivity. For example,
the idea of symmetry breaking in the field of elementary physics by Dr. Youichiro
Nanbu was derived from the theory of superconductivity.
Thus, the phenomenon of superconductivity may seem to be special. Even so,
almost half of all elements show superconductivity. This means that superconductors are not minor substances. In addition, the E-B analogy, the main principle in
present electromagnetism, can be made more rigorous by the introduction of superconductivity into Maxwell’s theory, which was completed before the discovery of
superconductivity. In other words, the existence of substances with zero resistivity,
i.e., superconductors, could have been predicted in the 19th century.
Electromagnetic phenomena in superconductors can be described by first principles that assume the minimization of the relevant energy, since the phenomenon
is reversible because of zero resistivity. On the other hand, irreversible phenomena
such as electrical resistivity can be easily found in the world. The mechanism of
irreversibility has not yet been proved theoretically. In this sense, superconductors are pure materials from the viewpoint of physics. Even so, the electromagnetic
phenomena in superconducting wires used for electric power instruments, etc. are
irreversible. This irreversible nature is largely different from irreversible phenomena
such as electrical resistance in normal metals but similar to friction: When an object
does not move due to friction under a driving force, there is no energy dissipation. If
a driving force that exceeds the friction moves the object, energy dissipation occurs.
v
Today, MRI systems with superconducting magnets are commonly used in hospitals,
and commercial superconducting linear maglev trains that connect Tokyo and Nagoya
in Japan in 40 min are scheduled to start in 2027. Thus, superconductivity has become
well-known. In addition, it is known by people who are interested in our global
environmental problems that the introduction of superconducting instruments and
power cables has great potential to contribute to suppression of CO 2 emissions.
Superconductivity is a peculiar phenomenon in which electrical resistance disappears when a superconducting material is cooled down to very low temperatures.
Thus, it has been investigated for a long time in solid-state physics, and many scientists have received Nobel prizes for work based on superconductivity. For example,
the idea of symmetry breaking in the field of elementary physics by Dr. Youichiro
Nanbu was derived from the theory of superconductivity.
Thus, the phenomenon of superconductivity may seem to be special. Even so,
almost half of all elements show superconductivity. This means that superconductors are not minor substances. In addition, the E-B analogy, the main principle in
present electromagnetism, can be made more rigorous by the introduction of superconductivity into Maxwell’s theory, which was completed before the discovery of
superconductivity. In other words, the existence of substances with zero resistivity,
i.e., superconductors, could have been predicted in the 19th century.
Electromagnetic phenomena in superconductors can be described by first principles that assume the minimization of the relevant energy, since the phenomenon
is reversible because of zero resistivity. On the other hand, irreversible phenomena
such as electrical resistivity can be easily found in the world. The mechanism of
irreversibility has not yet been proved theoretically. In this sense, superconductors are pure materials from the viewpoint of physics. Even so, the electromagnetic
phenomena in superconducting wires used for electric power instruments, etc. are
irreversible. This irreversible nature is largely different from irreversible phenomena
such as electrical resistance in normal metals but similar to friction: When an object
does not move due to friction under a driving force, there is no energy dissipation. If
a driving force that exceeds the friction moves the object, energy dissipation occurs.
v