I noticed that, since Magic is so delicate, there is no way we've gone through 4 eras with magic, without some mage messing up a conjuration spell, or an experiment on atherius. The court mage in Riften talks to you about her experiment(the dialogue is on UESP, http://www.uesp.net/wiki/Skyrim:Wylandriah )look for the part where she asks, "And I'm sure you've completely worked out how to counteract complete dimensional collapse, right?" If destroying everything is this easy, surely some clueless summoner would've accidentally done it.

BTW, I am by absolutely no means, an expert on this subject; I was just curious. Could any descent mage destroy mundus with an experiment? or does it not work that way.

Mundis is pretty heavily protected by wards enacted by beings far beyond any mortal mage, and sustained by the divinity of a murdered God. It's pretty damned resiliant. In almost all cases where there are manor magical failures, it's a backfire which obliterates (or does something worse) the caster.

Considering how reckless people like Manimarco have been with magic, I think it's pretty safe.