[Diamond]

But when you go into the realm of the quantum world, things happen without a cause. A number of theories have been put forward that a allow the universe to exist, like a quantum event, without a cause.

Even in the various theories to which you refer, a quantum world is still not absolutely nothing, but a necessary set of physical conditions. Things cannot happen where there is total nothingness because by definition there are no things in total nothingness. A quantum vacuum is not nothing, and fluctuations in a quantum vacuum do not constitute an exception to the principle that whatever begins to exist has a cause. The universe still has to have a source, and appealing to arbitrary necessity by saying that it just happens to exist is not a reasonable or satisfying explanation.

Isn't that the whole point of science anyway; namely, looking for rational reasons for things? Our scientific knowledge about the physical universe is based on our understanding of cause and effect, and it is therefore reasonable to assume that the universe itself has a cause, and so is contingent.

Cordially,

[nimdoc]

I have always thought of space as a potential, not as a cause. That is an interesting thought. I wonder if anyone out there is well enough versed in string theory to comment.

The universe still has to have a source, and appealing to arbitrary necessity by saying that it just happens to exist is not a reasonable or satisfying explanation.

To say the universe just happens to exist is no more or less reasonable or satisfying than saying that a creator just happens to exist. Neither statement is scientific - they are both metaphysical. (One physicist has said that the universe must exist because it is logically impossible for it not to exist. Now, repeat that slowly 3 times, then say it backwards 3 times for good measure.)
I have my doubts that this question can ever be resolved in a “scientific” sense.

To Be, or not to Be, that is the question.