Can we define life

Can we define life?
Simply it’s the difference between a walking man and the one resting in his graves! But why should there be life on earth? Is there any purpose? We think that everyone of us has their own purpose on mother earth and we do our duties sincerely. But is that how the world works? Imagine if there is no life on earth! It will still be spherical in shape, having days and nights, ebbs and flows, Mountain and valleys! The continents would still move and earthquakes would still happen. Then why are we here?
What happens to a life after death? Will it wander around the loved ones as they say? Or is it just a form of energy which can convert itself to another form, say temperature or light? I always ask myself this one basic question and I never found an appropriate answer! “A piece of metal is made up of atoms. A human body is also made up of atoms. But the human body “Lives” whereas the metal piece just doesn’t”. What makes us to move or control our atoms to synchronize and do work. Is that energy which controls the atoms called life? Put it another way, life is a form of energy which controls a group of atoms to perform certain Physical/Chemical actions.
We still obey the rules of physics as the metal do! So we are not miracles on earth. According to the above definition of life, when appropriate form of energy is applied on anything it can give life to that thing! (Think about Magnetism). But even if someone could define what life is in some stupid way as I did, the question “Why Life?” would still remain unanswered.
When things are unanswered they become miracles. Would we gain knowledge about life and the beginning of life on earth?