But what precisely are they testing? Which hypothesis of theirs? It does of course seem obvious that thay simulate it to test _something_. To me, that does not

But what precisely are they testing? Which hypothesis of theirs? It does of course seem obvious that thay simulate it to test _something_. To me, that does not really satisfy the "Why" question, though to a certain degree it does answer it, albeit without being specific. It's akin to asking someone "Why do you need a particle collider?" -> "To test something". I assume you'd like to know what they are testing :-)