Currently I’m reading a fascinating but challenging book by Sean Carroll, an American theoretical physicist. It has the title “The Big Picture: On the Origins Of Life, Meaning Anad The Universe Itself”.
One of the subjects discussed is abiogenesis which the origin of life. The truth is that we do not have a single agreed-upon definition that clearly seperates things that are ‘alive’ from things that are not. NASA has a working definition but it may be that, in the future, we find something beyond Earth but cannot be sure whether it constitutes life or not.
Although we do not have a hard definition, we know that there is something called life and that plants, animals and humans here on Earth fall into this definition, although – especially in the face of scientific developments in medicine and robotics – we cannot be sure of the exact scope of the term.
Even more confusingly, we do not know how life on Earth originated and how life outside Earth might originate. There are all sorts of theories, taking the cell as the basic unit of life and hypothesising about metabolism-first or replication-first processes. Carroll is convinced that “There is no reason to think that we won’t be able to figure out how life started”.
What he is clear about is that “there is only one world, the natural world, operating according to the laws of physics”. So existence, whether at the levels of the sub-atomic world, our human-size world, or the whole universe itself can be explained completely and only by physics.
So no need or case for any metaphysical or supernatural concepts such as God, life-force, soul, spirits, afterlife, miracles, magic and the like. He accepts that there is still a great deal we do not know, but argues that we can only achieve knowledge through science. Those who argue otherwise have to provide evidence for the existence of metaphysical concepts and crucially explain how the metaphysical impacts the physical and can contradict the laws of physics with forces or processes that cannot be detected.