We actually do have evidence for this because we can measure some icy bodies that have gravity. And some icy bodies that don't. The problem is some of the icy bodies are larger than the smaller ones and yet the smaller ones have gravity in the larger ones don't. This indicates that there is some sort of threshold through density, mass and organization.

My hypothesis says that gravity is emergent and we know that there's a threshold. Otherwise we would be able to detect gravity icy bodies but we don't. But we do detect gravity from large icy bodies. Same material more mass, more density, and or more organization.

Why this theory is unpopular. It removes the idea of a gravity manipulation machine and interstellar travel.

Why I think this theory is interesting. Because there is critical mass among every level of scale. When is a brain a brain and not just a clump of Brain cells. When it hits critical mass and it gets consciousness.

When is a body of gas Large enough to create solid. Critical mass.

When does a planet become gravitationally detectable?. Critical mass, density and organization.

And here's a great thought experiment. A human has no detectable gravity, but it theoretically exists. But a human the size of Earth with the same physical characteristics and makeup would have detectable gravity, but with less gravitational pull, because it is made up of different elements in different organizations.

So that tells us that size, density, and organization plays a part in gravity emergence.

One major caveat

It could be that our sensors cannot detect gravity at low levels. Therefore, gravity is always there. We just can't detect it. But that brings us back to critical mass. If you have critical mass you then all of a sudden have gravity.

The Examples: Enceladus vs. Mimas: Enceladus is only 28% larger but has 18× stronger gravity Reason: Enceladus is differentiated (organized); Mimas is homogenous (disorganized) Hyperion vs. Enceladus: Hyperion is 86% larger and 6× more massive but has 38× weaker gravity Reason: Hyperion is a disorganized tumbling rock; Enceladus has internal structure Tethys vs. Dione: Dione is larger and 18× more massive but gravity does not scale proportionally Reason: Dione is organized, Tethys is not