Theory of momentariness -- do things arise ex nihilo?
This is essentially the question: "Does X exist?"; "Does X not exist?" which are questions the Buddha puts aside as not being helpful towards achieving the goal. Whether or not X exists, there is pain (dukkha). This is the problem that is dealt with in the Buddha's system.

The idea of 'cause', as 'hetu' and 'nidana' and 'paccaya' and a half dozen other terms are translated (including 'ahara' food!), is an error. "Hetu" the most reasonable candidate for 'cause' means 'driving force' (something like the teamster's 'giddy-up!'). Cause remains a mystery that is not dealt with as it is irrelevant to the solution of the problem of pain.

What we get in the Paticca Samuppada (and other formulas dealing with the origin and ending of things) is not a description of cause and effect (no matter how often it is translated that way -- it makes no sense as a cause-and-effect description) it is a description of causal association (aka: Bhk. Thanissaro: requisite condition; aka: proximate cause, economic cause). 

Causal association can be seen. 

That is the point.

We deal in this system with what we can see and know for ourselves; what we can do something about ourselves.

"It cannot exist without it" does not equal "cause."

We cannot see the 'cause' for the appearance of aging and death from birth, but we can see that without birth there would be no aging and death. 

So without needing to deal with 'cause', we can know for certain that the result, whatever the 'cause' may be, can be eliminated by eliminating birth. And so on for the other causal associations.