As you probably know, the big-bang theory says the universe resulted from a small ball of energy exploding. The big-crunch theory says that gravity will eventually cause the universe to contract again into a small ball. The cyclic-universe theory says that this ball will then explode again and so on.
The particulate-universe theory says that before the whole universe experiences a big crunch, smaller parts of the universe will have a big crunch. At first, this may seem no different than the big-crunch theory. But the particulate-universe theory also says that these miniature big-crunches will experience miniature big bangs before the entire universe completes its big crunch. The result is that people in these miniature big bangs will think that what they see is the whole universe even though they are just seeing a part of it.
A big controversy about the big-crunch theory is that there might not be enough matter in the universe for there to be enough gravity for the universe to actually converge again. The particulate-universe theory side-steps this argument because we already know there is enough matter for parts of the universe to converge.
It seems very unlikely that our observable universe is the whole universe. It is unlikely because, if we follow the process, we see that parts of the parts of the universe form in a recursive fashion. Eventually a fractal pattern would form where, in all likelihood, our observable universe is arbitrarily small compared to the whole universe. This is an embodiment of the notion that our universe is an atom of some other universe. However, a partial universe would appear to change size while atoms don't; perhaps relativity causes the atom's expansion to be hidden.
In any case, it makes we wonder whether there actually is a single whole universe. It seems more likely to me that there are larger universes all the way up. This paradox can be explained as a single universe which loops on itself via a higher dimension. This seems most likely because it analogues all the fractal processes we see in three-dimensional objects which recursively progress through the higher-dimension of time.