One other thing, gravity is not a hoax, here are a few examples:
The moon (and all other satellites), orbits the earth every ~27 days. If gravity didn't exist, then the moon would shoot away from the earth at an approximate right angle due to the centrifugal force acting outwards with no gravity to pull it back in. Also, if the "flat earth" were actually accelerating upwards, then the earth should crash into the moon.
The Great Pyramid of Geeza (or however you spell it), since it takes the mass (not actually mass) of 3,600,000 tons, has been proven to SLOW DOWN TIME by a tiny bit. Due to gravitational time dilation, there can (almost) only be one explanation for this phenomena, which is that the incredible mass allows for a decent gravitational field to be created (technically 'created' wouldn't be the best choice of wording'). This is proof that gravity exists and is not a hoax.
PS. The reason why I mentioned the Pyramid instead of in space or near a black hole is because it is something that can be proven while still on earth. Why go to space to test this theory when by the time we are in space, we can just see how round the earth really is...