What are your suggestions for a physics engine that satisfies the following criteria?

1. Capable of calculating collisions between multiple concave mesh-based colliders
2. Handles many collisions going on at once (for instance one mesh being wedged between two others, which themselves may be wedged between two meshes)
3. Does not allow for collider passthrough, even at high speeds. For instance, if I am applying force to a programmatically hinged object that makes it spin, I do not want it to pass through another rigidbody that it collides with while spinning. I have this problem using PhysX
4. As implied before, reacts well to hinged objects, preferably has its own implementation of a hinge, but I am willing to program my own. The important part is that it has some sort of interface that guarantees accurate collision tracking even when dealing with these things
5. Platform independent -- runs on mac as well as PC, also not tied down to specific graphics cards

I think that's the best way to explain what I am looking for. Basically, I need SUPER reliable collisions. Something that can't be accomplished with a simple ray casting approach that sends a ray from the last position of the object to the current position (as this object may be potentially large and colliding with small objects via rotation)

Bonus points for also including an OPEN SOURCE engine.