As I said in another post, you aren't required to accept proof, or to state that you do if you do.
As I said many times, you can make as many assumptions as you want, it doesn't mean they are real. Saying ''therefore something outside the universe made it'' doesn't mean it's true since you have no evidence of it.
Except that such is what the universe shows us all over the place. Nothing in the universe makes itself spontaneously without something else making it. And the "something else" isn't the thing that it makes. This entirely means that something that is not the universe or of the universe made it. Since we don't seem to have a scientific clue about what made the universe other than some science theory, it's something outside the universe, because if it were in the universe, we would have at least a few clues.
Science agrees with that in big bang theory. I don't have to prove it. Science already does. Wanna know more? Research BB. Or hit the religions if you like the "God" idea better.
''Nothing in the universe makes itself spontaneously without something else making it.'' How do you know? Do you know how everything is made in the universe?
You see? That's the thing about science and the universe. We don't really know anything in the universe 100%. But science judges things by vast majorities. One great example is evolution.
We see countless number of living things that we can prove exist and change by adaptation, like-begets-like, and simple change. But we don't even have one proven example of evolution... proven because we know that it was evolution and not adaptation, like-begets-like, and/or simple change.
Science is wise in this respect. They leave evolution in the theory category. It's a bunch of talkers, hopefuls, the moneymakers, and media who have kept evolution alive as a theory, when it should have been dropped long ago, or even never elevated to theory status.
The whole evolution thing is, itself, proving that it is stupid, and is proving God thereby. Or do you have something else...
Didn't answer the question. How do you know everything is made by something and not spontaneously appearing.
Well, since I answered the questions many times over for you, and essentially proved it to you, should I supply the links? Should I re-post it all? Should I say it again?
You really need to get out there and do your own research.