I asked myself, why is there gravity?
This has spiritual implications, not just physical ones; and perhaps the reason that physics can't understand gravity is because gravity is a metaphysical phenomenon, not a physical one, and displays none of the conventional properties that we expect to see when fields, forces, and particles are measured with instruments. It is, in fact, one of the fundamental mysteries of physics: what mediates the gravitational force?
One needs to develop a personal sense of inner gravity to investigate this for many metaphysical point of view; and the inner sense of gravity is born within the inflow, the arrival of the divine influence. So gravity is an active or conscious force related to the action of divinity, not some mindless physical property that acts without intelligence. Gravity is, in fact, directly related to the intelligence of God, because it serves as the prime organizing factor for the collection of material manifestations into ordered systems.
The question relates to the nature of suns as apertures opening up from the realm of the Divine. An outflow of the Divine into the material universe takes place, which manifests as light, heat, energy, and the associated creation of matter; but the return of the divine into its original source of arising is mediated by the force of gravity, which exerts a force of attraction back into the divine that is, in the end, exactly equal to the quality of emanation and radiation that takes place as the divine enters the material universe.
If we want to understand this from the point of view physics, we would have to invoke the idea of the multi-verse, that is, multiple universes, of which this one (that is, the one we're in) presents as only one bubble. The idea is in fact correct, when understood from a metaphysical point of view, because each "bubble" universe is a realm of action — only one of an infinite number of them — into which the divine penetrates before moving back into its own source. It is a circulatory system. We might liken it to the alveoli of the lungs, hollow cavities in which the exchange of vital substances takes place. Those who read Swedenborg in any detail and are capable of understanding how sophisticated his correspondence analogies between biology and the heavenly realms are will understand exactly what I am saying here; in any event, our universe is like one of countless cavities in one of the "lungs" of God, in which essential properties of Being are breathed in and out. In this analogy, solar systems are the individual "atoms" that participate in the process — and galaxies are somewhat analogous to to the molecular structures.
So you see, the nature of the universe is far more organic and mysterious than it appears to be. Gravity is the force that draws all of the material back into the Divine; and it operates not only on a macroscopic scale, where it organizes planets in solar systems, it performs the same function within us.
If we awaken to the sense of gravity in us, not only are we receiving the inflow of Divine influences into our Being; we are also participating in a circulation in which we return them to their source. Because one of our essential responsibilities is to return these impressions to their source, it's important for us to understand, sense, and cultivate our inner sense of gravity.
May your soul be filled with light.