[quote=@Rhymer]
[u]most important thing would be to establish the source of magic[/u] 

[/quote]


Okay. 
I vote for magic always existing as a force. Science started to understand it, or at least started to understand how to harvest it. Discovering new set of laws.
Magic can be performed only by gadgets/machines that were specially build to obey the magic laws. 

as in more specific what the source could be in those machines hm... I get two ideas:

*Pieces of mater from earthly origin in special containers (varying in size), inside which magic laws are held active.
I imagine something like star trek ship core, but instead of anti mater and only getting energy as a out put we use earthly matter and have as output something that alters laws of nature.

*Chips, I pull the inspiration from like quantum chips. Something like they can compute alteration to reality and allow the impossible to become reality. Like abusing chaos theory (butterfly flapping its wings effect) and the like XP?

p.s. please do tell me if I am going too deep in things too early.