thanks for all the great explanations! yeah, I wasn't so sure it would be enough to rip the atomic bonds apart either, but just thinking about that scenario made me ponder whether or not u'd feel the forces pulling at u from all sides. thanks!

@Retrokatze: I agree. Your comments make sense. But that all relates to acceleration. I'm not talking about the acceleration that the body is moving at. I'm talking about the gravitational forces acting on the body. Would the gravity pull apart the atoms of the body traveling through the tunnel?

Forget for a second that the body is traveling at all. Let's just say that at the very center of the Earth, there is a hollow center. So picture a spherical hollow room at the center of the Earth surrounded by miles and miles of rock around. If a person were to be placed in that room, would the gravitational forces generated by the mass all around him rip the atoms of that man's body apart? No acceleration involved...

If I understand and remember my high school science correctly, we are pulled to the Earth because of the mass that it has. The mass of the Earth is what creates the gravitational field which keeps us from flying off into space. If that's the case, then when the person flying through the Earth-tunnel hits the dead-center of the Earth, would the gravitational forces from the mass all around him pretty much rip him apart? Just a thought...