In 1921, Theordor Kaluza, a Polish physicist, published a unified theory of electromagnetics and gravitation.
His paper was recommended for publication by Albert Einstein, who had had the paper for two years.
In that theory, five dimensions -- four space and one time -are utilized in the basic model. This gives a 5-dimensional spacetime.
In the model, electromagnetics and ordinary gravity are two aspects of a single more fundamental field: the 5-space gravity field.
Electromagnetism is that part of the 5-field that operates (bleeds-off) in the fifth dimension.
The ordinary 4-space G-field is the small residue that spills over into our ordinary 4-space, and doesn’t slide around into the fifth dimension and bleed-off there as electromagnetics.
Implicit in the theory, but not explicitly stated, is the fact that the 5-space G-potential bleeds-off in two fashions: (1) in the 5th dimension nearly unopposed, to produce what we see as EM force fields, and (2) in the ordinary 4-space we live in, which we see as ordinary gravitational field.
Normally almost all the force field bleed-off is in the fifth dimension as EM; only a minuscule bit bleeds off as 4-gravity.
Just as one example, between two electrons the 5-space G-potential bleeds-off into electric force field about 1042 times as much as it bleeds-off into 4-space G-field.