My friend thinks that gravitons (the essense of gravity) are from a different dimension.
He thinks that large density of matter (the sun for example) creates a rip between dimensions causing "gravitons" to enter our dimension. Most people can say that gravity is the source of all energy, without it stars would not exsist.
So this brings me to the point that maybe there is an infinite amount of dimensions. Each dimension is supplying "a source of energy" (like gravity) to the dimension below it.