Any theories about universal expansion due to action at the universal event horizon? I'm curious if there are any theories about the increasing rate of the expansion of the universe that are centered around gravitational pull from matter outside the event horizon of either the observable universe, or the entire universe?

Since observations point to a uniform rate of expansion in all directions, it would make sense (as most theories speculate) that some force is at work. Most theories invoke dark matter/energy, but is it possible that it is simply gravity?

In my thought experiment I considered this in two scenarios:


Finite and Boundless Universe: There is no limit to the size which the universe can expand, but being finite in size and expanding outward, the accumulation of matter at the very edges of the universe is more dense than that in the observable universe. This dense outer boundary is constantly pulling the rest of the universe towards it. As more matter accumulates at the horizon, gravity increases, and the rate of acceleration expands.
Finite and Bounded Universe: The universe is limited in size, as expanding matter and energy reach the event horizon of this limited universe, it is compacted like a black hole that surrounds the entire universe. As the maximum size is limited in this scenario, matter and energy would infinitely accumulate at the horizon; in turn constantly speeding up the expansion of the universe as all matter is pulled outwards towards the ever-growing horizon.


I'm quite the astronomy nerd, and have a good understanding (as much as a non-professional can) of the physical laws governing the universe on a large scale, so I know there are some immediate problems you could pick apart in the above scenarios, this is just an idea I had to jot down before I forgot. I am interested in whether or not any fleshed out theories similar to this idea exist.
There are no such theories because there is an immediate problem with both scenarios as stated.

It is a fact that a spherical shell of material has no net gravitational influence on material anywhere inside it. https://en.wikipedia.org/wiki/Shell_theorem