For the longest time educators had repeatedly taught me of the problem with gravity. We have four fundamental forces electromagnetism, strong interaction, weak interaction, and gravitation. We are able to combine three of these forces but not gravity hence the ongoing development of quantum gravity. Yet according to general relativity, gravity is NOT a force, but a fictitious force no different from centrifugal force according to wikipedia. http://en.wikipedia.org/wiki/Fictitious_force If gravity is not real and is not mediated by a particle what is their to combine? Do we have any evidence that gravity is "real" and is mediated by a particle? If not what is the problem? What am I missing here?