Ok, I read this article at MoJo's and it does not make sense to me. Maybe someone here can explain it a little more clearly.
The idea here is that the trampoline illustrates the concept of warped spacetime, and it's adequate for that purpose. But if you place a stationary marble on the trampoline in the picture, what causes it to suddenly start rolling toward Earth? This only makes sense if there's some kind of secret gravity machine underneath the trampoline that pulls on the marble. This is not just oversimplified, as complex concepts often are in works for general audiences, it's flatly wrong. But even notable scientists continue to use this metaphor in books on relativity.