You can use the sea, and the bubble in the sea as an example of Convex, and concave. The sea creates the bubble by removing the sea from the area of the bubble. The bubble is concave sea, and the sea is convex. This relates to a Neutrino travelling through matter. The neutrino a bubble through matter would be a concave version of matter, created by the surrounding matter. A black hole would be a concave version of spacetime created by the surrounding spacetime. You can call this concave version negative mass, or negative scale. The bubble in the sea is negative mass of sea, because where there should be sea there isn't any sea. The bubble in the sea however is only an poor example of a hole in spacetime, because the bubble in the sea still has forces from each of its points at planck length that are still convex. A black hole has each point as concave.
In spacetime..
Convex bumps convex
Concave bumps concave
But together convex to concave just create a flat line.
So in spacetime the convex, and concave behave as gravity, and magnetism.. two poles. + and -.
And act as independent physics, frictionless to each other. They usually move in opposite flow directions. They don't have to, but the area of least resistance is usually in the opposite direction. A positive force can scale down to become a negative force, and then it will switch directions without stopping. This allows for perpetual motion, and it gives you time as a circular scalar motion.
When we use the degrees of a circle 0 to 360 we have closed the ends of zero and completed Newton's 3rd law, that zero has an equal opposite which is 360. We don't think of it that way, but you can use 1 to 180 and -1 to -180 and complete Newton's 3rd law that way. We tend to think of scale as always positive, or positive mass. But with Black Holes you need the mathematics of a circle...
Example
Mass = 1 to 180 and -1 to -180
So the Black hole is not infinite mass, it is circular mass that expands backwards after it has flattened out, like a bouncing ball, but folding inside out at the rebound point... frictionless.
After the rebound point of mass a hole is expanding outwards. The incoming mass passes through the out-flowing hole, so there is no friction. Gravity moves towards the Earth, and the magnetic field passes out of the Earth together. The magnetic field is the outflow of gravity to release the pressure of gravity meeting up at the centre of the Earth.
Now all of the forces are bump forces, and pull forces have been eliminated. You can take pull out of the dictionary.