Ha, ha, ha, I find it very funny when disturbed people such as the beast get angry and say gibberish like "Also you smell because you don't wash" as though that's going to anger me. Mate, it just makes you look stupid when you get angry that you have no argument. It's better to just accept that you were wrong and move on with your life.
beast, your lack of intellect is obvious from the fact that you do not understand the simple mathematical concept of logical implication ('if A then B' or 'A => B'). Gravity is 'A'. The RE is 'B'. Now think 'A => B' or "Gravity => RE', or in other words 'given the fact that gravity exists, the earth is round'. Or how about "Gravity causes the earth to be round". Or "Because of gravity, the earth is round". Does that make any sense to you?
You asked me to explain the existence of gravity using the RE model, so basically B => A. That is illogical. The 'reason' for gravity is NOT the fact that the earth is round, but vice-versa: the earth is round because of gravity.
As the name suggests, the RE theory proves that the earth is round, not why gravity exists. However for the RE model to be strong, it needed to be based on strong axioms (gravity being one of them) and for the axiom to be strong, people made observations to prove that 'it stands'. Therefore they observed other galaxies, stars and planets and realized that their movement was consistent with gravity - in other words they said, "Even though we don't know WHY gravity exists, we know that it DOES exist BASED ON how objects behave in the universe". Then they said (to simplify things for you), "Now that we've agreed that gravity exists, let's BUILD the RE theory BAESD on this axiom called gravity (axiom because we don't have mathematical proof, but we have strong observations)". After the RE theory was built, it was able to answer why the earth was round; it doesn't explain why gravity exists. I believe that if a theory proved why gravity existed it would PROBABLY be called the "Gravitational Theory", or "GT".
Your question "Why does gravity exists?" has nothing to do with the fact that the RE theory is strong, nor does it prove that the RE theory still leaves unanswered questions. In fact, your question is entirely out of context.
However, the FE theory lacks an axiom to be based on. It's just an assumption. The fact that you believe in assumptions rather than observations shows that you are a very weak-minded person.