What is gravity? Is it........

Question

a pure force?

a curve in space?

particles with special powers?

Answer 1

Gravity is the curvature of space-time exerted by every object with mass.  So, number 2 is the most accurate.

Answer 2

It can be modeled as all of the above.  Classically, it is an attractive force between masses.  General relativity models it as a curving of space and time by energy.  Quantum field theory models forces as exchanges of particles.  So most likely there is a particle that mediates the gravitational force, which we call the graviton.  I'm not sure that it has an special powers however.  In fact, it is so weak that we may never detect it.

Answer 3

Assume for a second that it is one of the fundamental forces in the universe. All such forces are mediated by particles, the strong force has the gluon, the weak force has the W and Z bosons, the electrostatic force has the photon. And though we have yet to see it, we predict that gravity has the graviton.

Hence a "pure force" and a "particle with special powers" are really the same, since any such force is mediated by particles.

So now the options are fundamental force, or curvature of space. To put it another way, the options are quantum field theory or general theory of relativity.

Both of these theories seem to be holding up pretty well, so I ask you, why can't it be both? Lots of other things manage to be two things at once, light can behave as particles or waves, as in fact can electrons and many other particles. Some things can even be in two (or more) places at once in what is called a super position.

How about this, what if it's neither? The maths we use to model the universe is just that, a model. It can be an arbitrarily complex and accurate model, but it is just numbers.

We have no intuition on scales of the very small or the very huge, because we live in the middle, on a planet that is gigantic in comparison to the atomic level, and miniscule in comparison to the scale of the universe. We need analogies and models in order to relate to these phenomena, and we term things particles or waves when in fact they are neither, but we need to call them something, since we can't even comprehend what they might actually be.

So for the sake of the theories and the maths, it's both of those things. In reality it is neither.