Science is oriented toward prediction and is getting quite good at it. We can predict where a satellite will intercept Venus, etc. So we get spoiled at bit by this heady success and start asking well, can we predict our own death using science? But although science can predict a lot very well, it still is clueless about WHY its formulas work. All we have are formulas that, given much trial and error, are changed until they are effective. It will be thousands of years before we understand what is really going on here - maybe then we can define life (we can't right now) and, yes maybe, begin to predict death too.