Time and gravity are not abstract ideas, both are measurable like temperature and weight. One is a property of space-time itself, the other is one of the fundamental forces, very likely caused by a physical particle.
Life is simply a bunch of chemical reactions tied together in a way that allows us to think. There's nothing beyond the physical form, even your very thoughts are tied to the chemical reactions in your brain.
If you want a proof, simply look at anyone who has had a dramatic shift in personality after a head trauma. If there was a "soul" (or whatever you want to call it), wouldn't their personality remain the same?