Causes and Effects in the quantum world I am debating with a person about questions of causes and effects in the quantum world, and some questions came into our minds, hence I would be very happy to know what is "your opinion" that is, what physics says about causes and effects in the quantum world.
In particular: take a process like spontaneous emission, or virtual particles fluctuations in the quantum vacuum. Could we claim the cause is undetermined or is there an explicit cause? Does Heisenberg rule the whole things, and would the same Heisenberg principle be a "sort of cause"?
Does spontaneity preclude its need for a direct cause (event A directly effecting event B) at all? 
 A: The premise of the question that "cause" or "effect" are well-defined physical notions at all is simply wrong, already classically: 
Norton's dome is a perfectly fine classical Newtonian system, yet it has indeterminacy: It is consistent with the equations of motion that the ball balanced at the top of the dome can start rolling down at any point in time, without any external influence. This shows that classical Newtonian mechanics already does not admit straightforward notions of "cause" or "effect" in the sense that effects would necessarily need causes.
Therefore, physics says nothing about causes or effects, neither in the classical nor in the quantum world. Talking about causes or effects is an interpretation of the physical model, an ontology you impose on it, and not intrinsic to physics as such.
A: I think this question will be closed because it comes down to philosophy.
But FWIW, my take:

Causes and effects in the quantum world

is a very open topic, hence the many  different interpretations of what the quantum word actually is. 

since it has to do with reality and the laws of the universe.

I don't know what reality is either, except that the quantum world is more real as an accurate picture of physical processes, than the classical world, but how far does that get you? Again choose  your favourite quantum world interpretation.

take a process like spontaneous emission, or virtual particles fluctuations in the quantum vacuum. Could we claim the cause is undetermined or is there an explicit cause?

Physics has a law that says these processes are random, say the emission of radioactivity. If we had a better understanding of this process, then hurrah!!,  we can dump the random bit and replace it with a better explanation. As of now, random is all we've got, so that's real physics, in that it has a law "explaining" it, but obviously it's not a very deep explaination.

Does spontaneity preclude its need for a direct cause (event A directly effecting event B) at all?

We don't know if any process  is truly random, so currently this seems to depend on what you consider/define spontaneinty as. "Without apparent cause" would seem to sum it up, until we know more, if ever.
A: The standpoint of standard Quantum Mechanics is very simple. Single processes, like the emission time of a photon from an excited atom, or the location of impact of a photon or electron on a screen after passing a double slit, are not causal, but random. There is no cause for a single particular outcome of the experiment. When considering the probabilities of such processes by averaging over many such single events, there is a causal law for the probabilities, which is determined by the quantum mechanical wave function obtained from the Schrödinger equation.
A: We do know that "spontaneous emission" and other fundamental things are not completely physically independent. For example, we know that they can change their rate when mass is moving.
But there is no agreed-on conception in physics of what is happening at the quantum level, although there are a variety of competing heuristics, and each time one side thinks it has staked the other through the heart and nailed the coffin lid down, the lid flings off and the creature lurches back out grinning - and thus it has been since the first half of the 20th century.
Not a great deal of progress has been made since, mainly because many physicists have tried to stop talking about it, or have even contended that they don't need to talk about it, and a generation of physicists have spent careers in an environment that attempts to suppress such discussion (or, when it involves the most prominent physicists, to disown it as obiter dicta and personal musings on "philosophy", rather than serious work in the field of theoretical physics, whether it be correct or not).
EDIT: to anyone who disagrees with any aspect of this post, it would be helpful (for all our sakes) if you were to review the further discussion that was had on it, and to leave such further remarks as you may feel justify its contradiction.
Right of Reply: @EmilioPisanty makes some forceful points about the clarity of my assertions. 
He makes the point that work in "quantum foundations" is ongoing in the field even if a settled resolution of the multiple QM interpretations has not been achieved. He differentiates between "progress" defined in terms of furtherance toward a resolution of a question, with "progress" defined in terms of the achievement of a resolution and a moving-on from the question. I should be clear that I use the word in my answer here in the latter sense. He argues that, otherwise, the reader may well think no useful work is being done on the question at all!
He also argues that work was never totally halted in the field - a point on which I agree with him - whereas my original words are capable of implying that it stopped completely. On the contrary, it is only my position that work on "quantum foundations" was widely devalued in physics, and that therefore fewer physicists turned their time and attention to it than otherwise would have if it had instead been lauded as an important outstanding question in physics.
Emilio acknowledges that this "attempt to suppress" was made, but denies that it was successful, and denies that the attempt had any appreciable effects on the progress in this area of physics. Therefore, if the long-standing controversy over QM interpretations remains outstanding in physics, he argues is wrong for me to attribute this to "suppression". This remains a matter of difference between us upon which the reader would have to adjudicate.
EDIT: I'd also like to offer the following, from authors on either side of the issue, as particularly enjoyable reads:
Berthold-Georg Englert, On Quantum Theory:
https://arxiv.org/abs/1308.5290
Pablo Echenique-Robba, Shut up and let me think. Or why you should work on the foundations of quantum mechanics as much as you please:
https://arxiv.org/abs/1308.5619
