There is a source for everything. If nothing was, then nothing it would remain. It is a scientific fact that an effect cannot be greater than its cause. Therefore, nothing could not cause something. A beginning from nothing cannot be an adequate answer.
Nothing explains nothing.
So this leads us to the conclusion that something must have been forever. Something must be eternal. Therefore, if the universe was born from something that is eternal, then the cause for the universe must have existed outside of it because the universe is not known to be eternal. If nothing is eternal, then at one point something must have sprung out of nothing, but we have already established this theory to be unfeasible. Therefore, something must be eternal.