If the center of the earth was hollow and it was possible for a human to go there would said human just levitate right there in the center? If mass causes gravity and you're at the center then all the gravity would be pulling you out towards the surface of the earth in all directions enabling you to float right in the center.
If there was no core there would be no humans. Einstein thery of general relativity. Space is pushing on everything . because the mass is weighing on spacetime. Gravity doesn't pull it pushes
You would only float if.you were.perfectly.in the middle otherwise.you would.fall.to one side. With a hallow.core the gravity wouldnt.pull.to the middle but to each side
Stopping in the centre of the earth would be a problem. You would be traveling at terminal velocity around the time you reached the centre of gravity. You would only start slowing down once you were well on the other side of the lower mantle. Assuming you were to jump down a hole towards the centre of the earth. But interestingly enough, you would slow to almost a perfect stop as you arrive on the other side of the planet as the relative pull of the earth's gravity gradually slowed you from terminal velocity. It'd be a hell of a ride. What I've never quite understood is if and how the variable gravity of the inner planet would effect the transmission of P-waves. I wish I knew a geophysicist.