Why does gravity happen?

[6644kp]

I mean we know it exists and the size/strenght of attraction level but how does it actually work?

It seems our understanding is a bigger engine is faster but not knowing anything about the internal parts of the engine that make it happen.

[Jack04]

Its still something of an unresolved question. General relativity says that the force is the result of space-time curvature. The "force propagator" of gravity is still known as the graviton, although its existence as a force per se is largely contested in modern physics. It is likely that we will have to either experimentally identify gravitational waves or develop a theory of quantum gravity before gravitational propagation is properly understood. On the other hand, the electro-weak force is pretty well understood.

[6644kp]

Its still something of an unresolved question. General relativity says that the force is the result of space-time curvature. The "force propagator" of gravity is still known as the graviton, although its existence as a force per se is largely contested in modern physics. It is likely that we will have to either experimentally identify gravitational waves or develop a theory of quantum gravity before gravitational propagation is properly understood. On the other hand, the electro-weak force is pretty well understood.

Once it is fully understood how gravity works on could alter and change the force of attraction of large planets so as to allow for human settlement. Larger and smaller bodies than Earth could have the same level of gravity as Earth.

[Jack04]

No. Almost certainly not.

[Kanaric]

Anything is possible in the future even if it would seem as magic to us.

[Jack04]

Anything is possible in the future even if it would seem as magic to us.

Maybe, but our understanding the nature of the force wont change that. We understand electromagnetism to an incredible degree but that hasn't really allowed us to do anything of the kind 6644kp suggested (when corrected as a gravitational analogue, importantly). Its important to remember that gravity is a purely attractive force. Gravitational potentials cannot cancel one another out in the way electromagnetic potentials can.

[Sphere]

The person who could answer the OP would be in line for a Nobel Prize in Physics.

But to expand on Jacks explanation, for the other three forces besides gravity we have a "force carrier particle" model, where by forces are just the exchange of certain particles. Like two tennis players hitting a ball back and forth.

1.) Electromagnetic force = Photon Exchange
2.) Weak Nuclear Force = W & Z Boson Exchange
3.) Strong Nuclear Force = Gluon Exchange

And the connection between the Electromagnetic and weak force is so very well understood that is actually considered all one thing; named the the Electro-Weak force. The connection between the Electro-weak force and the Strong nuclear force is less clear, but it has been cobbled together into one thing called the "Standard Model".

So in short, all three of these things are currently under one unified theory that at this point is fairly well understood and mostly verified from experiment.

But then we have gravity. Right now, the general assumption is that gravity will turn out to be explained in a way simular to the other three forces, that all it is is the exchange of a force carrier particle such that

4.) Gravity Force = Gravitron Exchange???

But nobody can make this work mathematically. All the cheats and tricks ("re-normalization" is the word physicists use) that get the other theories to work, fail when it comes to gravity and you get answers like infinity and zero.

Fixing this problem, and thus getting Gravity to fit with the other 3 quantum forces so that everything is understood in the same way is called the "Grand Unification of Physics" , which is at this point still elusive.