One of the basic laws of science is “Conservation of matter and energy”.  Basically nothing can be created or destroyed, but rather transformed from one state to another state.  For example water can be a solid, vapor or liquid.  If one assumes that humans are a complex interworking of electrochemical reactions… among other things, then when one dies the electrochemical reactions change into another state.  The other “state” is the after life.  And if you start researching this topic you will find more and more scientists discussing a convergence between science and religion.  The Bible was in large part the “science book” of its time.  And it was not able to explain things in cold hard scientific laws, but relied on faith.   But today one really doesn’t need faith to know there is life after death.  Science tells us that there is indeed life after death.  What exactly life after death is… is not clear, but death is not simply a “dead end”.