PRIDE CHEKERAKaluza-Klein mechanism
Within this quest, a German Physicist Theodor Kaluza, was
working on achieving this, attempting to unify gravity and
electromagnetism, the only known forces at that moment.
It is said that, it all happened a certain day when Kaluza was
sitting in a room, besides of which there was another room in
which there was his nine-year-old son. His son was suddenly
surprised to see his father jumping on his feet, shouting a eureka
of excitement.
Indeed, he had stepped onto the shores of the grand unification,
the shores approached since ancient times. Kaluza, discovered
that when a fifth component was added to an electromagnetic
vector potential, representing Newtonian gravitational potential,
5 dimensional Maxwell's equations of electromagnetism would
be written.
In 1919, Kaluza sent his paper to Einstein, which was then
published in 1921. That was an outstanding classical extension
of general relativity into a 5D theory of gravity which has a
metric tensor of 15 components. Ten of these components were
concerned with a 4D space-time, 4 components of an
electromagnetic vector potential and one component of an
unknown scalar field named 'radion' or 'dilaton'.