[Skyli (OP)]

Just for a second assume that Space is composed of countless "cells" - tiny pieces that, like living cells, are constantly replicating in a process similar to mitosis. Like a cancer the "new" space created by such mitosis is pushing against its environment. However, this push is negligible compared to gravity so, in a massive environment like a galaxy or galaxy cluster, the new space is simply "squeezed" out through the gaps into empty space. In the empty space between galaxies the huge number of constantly replicating space-cells builds up a pressure that even the relatively tiny galaxies have to succumb to, thus pushing galaxies away from each other as the space between them "grows".

Would this not account for many of the phenomena that we put down to Dark Matter and Dark Energy?

[alancalverd]

Neat idea but what "environment" is it pushing against? And what drives the replication? It's potentially a neat conceptual model of an inherently expanding system but I don't see  any testable predictions coming from it.

[Skyli (OP)]

By "environment" I mean, in a nut-shell, the amount of mass present in a particular area of space. For example, a solar system is a very massive environment - enough gravity-generating mass to overcome the "pushing" effects of cellular space. In intergalactic space the environment is far less massive, just the odd particle here and there.
As for measurement, having a fair approximation of the mass of distant galaxies and a good idea of their rate of separation, it should be possible to ascertain the rate at which space "grows". Having that, we could put a particle in an extremely light container from which all other forces are excluded - I guess I'm talking absolute zero. The particle would not move or, at least, any movement based on the gravitational attraction between the particle and the walls of the container could be determined.
If the particle is in the exact centre of the container then space is growing all around it in equal proportion; the particle stays put. If, however, the particle is off-centre then the pressure of new space on one side will be greater than on the other and the particle would be pushed towards the nearest wall of the container at a rate greater than could be accounted for by gravity.
Some tricky measurements, for sure, but it would be great fun.