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Can the universe have been created from nothing?
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Not without violating the currently accepted laws of Nature.

''Nothing'' is modeled in quantum physics by the vacuum state - 
whether it is an empty input mode in a beam splitter or a quantum 
field without particles. So the question is whether a primordial 
vacuum could have dynamically changed into our universe.
 
Because of the conservation laws for momentum and energy valid in the 
standard model, it is impossible (under the currently accepted modeling 
assumptions in quantum physics) that a vacuum can turn into something 
nonvacuous in a region of space small enough such that gravitation is 
negligible. And indeed, such a thing has never been observed. 
 
If the universe at large is governed by a local field theory, all 
causes are local, whence the same remains true globally in the universe.