When scientists recreate the conditions that existed when the universe was first created and matter was formed, are they creating new micro-universes? Obviously, I'm not looking for evidence or convincing proof, but rather an opinion based on your understanding of the science and your ideas about the origin of the cosmos.
I'm not sure that they are creating micro-universes, since the matter that they use to create the collisions is inherently part of this universe. The giant super-colliders that physicists use create powerful electromagnetic fields to smash very small (sometimes sub-atomic) particles together. In doing this small black holes are often formed. These super small (and very short lived) black holes may indicate an irregularity in space/time. The creation of black holes indicates that dimensionality is extremely distorted, so rather than creating a new "micro-universe" it seems more probable that a short-lived parallel-dimension is created in phase with our own.
I like your question Tunsa but your probably not going to get any answers here, you should have asked it in the Astronomy & Space section.
Here on earth I'd think what they did would be affected by our gravity and atmosphere. But if they did the same thing in the vacuum of space who knows, maybe it would create a small universe within our own universe.
Like I said re-ask it in the Astronomy & Space section and you'll probably get some good answers from some very smart people.