Why can we not apply Science to look into any proposition we choose?

Lets say we apply science to model the creation of a universe. The result would be inconclusive. We would only prove that a universe could be created not that it naturally formed. 

Your in the realm of philosophy not science. Science requires data. That means observation and experimentation. We don't even know where 90% of the mass of the universe comes from. We don't know what gravity is. We know how it works but not what it is. 

Let me put it this way. The difference between science and science fiction is hard work. You would be selling science fiction as science.

Can science prove God ?

it's the job of science to figure out how the universe works not how it was made.

the question that is important is. Is the universe and everything in it an artificial creation or a naturally occurring event?

there are three answers to this question. The most important answers are yes and no.

Each person seeks to find an answer, each leads to inevitable conclusions. 

Any being that can create a universe, is powerful enough and smart enough to make it impossible to find them. If he doesn't want to be found. No human has the means to do so, science or no science.

Any answer to the question is religious. Leave science out of it.