Relativity shows gravity as warped space-time according to Einstein;

yet, Gunner Nordstrom may not have been totally wrong to theorize that

that gravity could be geometrically shown as an extra dimension.

The 3D planes X,Y, and Z are curved from flat euclidean space in a gravitational

field : this is evidence of geometric motion in an extra dimension ... call it "G" .

Therefore, you may move X,Y,Z, and G ... plus " Time " ... you may merge

time/space together into a simple "G" for "gravity dimension" . This is saying

that gravity is not a mere force, nor particle, but a motion through another dimension

where matter/energy is drawn inwards ... since relativity says matter and energy are

interchangeable the draw seems universal.

P.S.

The famous diagram of a bowling-ball on a rubber mat simply replaces gravity for Z " up-down" : really, you would have

X,Y,Z and delta-X, delta-Y, and delta-Z ... which could be X,Y,Z, and G. Is this correct?

Great analogy of dimensions in X, Y, Z coordinates :

If a line is moving X and curves it needs some Y ;

If a line is moving X , Y and curves it needs some Z ;

If a line is moving X ,Y and Z and curves it needs some G .

If you're going North, East, and Up , you're going 3-D ...

If you're going North, East, Up , and " Curving Space/Time "

you're going 4-D ( plus ) ...