I can't honestly tell if you are serious or not. Go outside with a telescope, look up. SPACE. "I believe" is never valid in arguments nor supportive. When you use "Well I believe" then you lost your argument because you are wrong when it comes to a proven fact that is generally accepted.
Basically what you are saying is, math doesn't exist. I was taught math in school, but I don't believe in it so it doesn't exist. I don't have any reason to believe it doesn't exist, I just don't believe in it even though I have a whole text book written by people with PHDs and Doctrites. Not to mention all of my collage graduate teachers are wrong because Math doesn't exist cause I believe it doesn't exist.
There are various elements that are found from space, stones collected and beought back, video recordings of planets and planetoids. You have the Sun which is hot and produces light. 2 things that cannot happen without it being 1) a giant lightbulb that uses a special filament to create light as electricity passes through it which also releases a gas as it makes light or 2) a ball of super heated gas that's on fire.
You also used Gravity...Gravity is scientifically proven. You believe in Gravity but nothing else in science? Gravity is one of the generally accepted facts that is disputed by scientists more so than space.
Questioning accepted truths is what Science is all about, but when all the sources all say the same thing and there is no room to question it further, its a fact that cannot be disputed. No one argues if Space exists. Its there you don't need a scientist to tell you its there. You can look at the night sky with or without a telescope. With a telescope you can see even more of space.