"...the essential differences between life and non-life. The line isn’t always clear..."
"...a checklist of characteristics of life e.g. growth, nutrition, metabolism..."

True, very difficult questions indeed.

Since I'm the one who brought up the issue, I shall put my neck on the chopping board and try differentiating life from non-life, using my own definition:

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In the broadest sense possible, a material life (as opposed to spiritual life) is an entity with a finite boundary that is capable of accepting one or more input(s), capable of processing the input(s) on its own accord (ie. it has a standalone intelligence) to produce one or more output(s).
x-x-x-x-x-x-x-x-x-x-x-x-x-x-x-x-x-x-x-x-x-x-x-x-x-x-x-x

Is there any scientist out there to discuss this with?

mjpb: 'Post hoc ergo propter hoc' is a logical fallacy. One that you really should look into.

Maybe one question should be asked: why are not the contributions of scientists such as Al-Biruni, Ibn al-Haytham, Brahmagupta or Su Song not considered science? Why are contributions of non-Christian origin ignored or even put down as superstitious mumbo-jumbo like astrology?

gz, your defintion needs serious refinement, it is so vague that in fact that it is operationally useless. Further, the term "stand-alone intelligence" as it applies to the definition needs to defined itself.

A solar powered calculator could fit that definition.

I don't know why people believe God could be proved or disproved by science. According to theology God exists outside the physical universe. Science is applied within the domain of the physical universe. These two domains do not intersect.

Bugsy,

It's paradoxical I know. I simply see the need to cover off what Celivia alluded to - that there are "...living things that barely fit the definition of life and non-living things that almost appear alive".

My definition is a one size fits all. I'm not willing to abandone/change it until I have explored it much further.

According to my definition, a solar powered calculator indeed has a life of its own - it turns on when light shines on it.

Now stretch your imagination - if that calculator is actually made of flesh and bone, the electronics inside are all replaced by their biological equivalence (if there are such things) and the processor chip replaced by a fleshy 'brain' tissue that performs calculations and it has ten 'eyes' that display the result of computation, then I would argue it is in essence a life-form, albeit a very primitive one that has no emotion, unable to metabolise, grow and multiply.

My definition extends 'life' beyond convention. A life-form does not need to be intelligent, it does not need to metabolise and grow to qualify as being a life-form.

Assuming a transcient life-form (with a short life span) is created in a test tube. By conventional wisdom it may not qualify as a life-form but my definition actually caters for this scenario, provided of course that it fits the criteria of my definition.

Any comment?

I will probably run out of comment quota soon, but I will just say that any definition of 'life' that can include simple electronic devices and machines, i.e. inanimate objects, is functionally worthless.

I must admit that finding an overarching definition that covers all the bases is difficult. Most just have a list of properties or criteria that must be fulfilled, but there are still certain grey areas, for things like viruses. Are viruses alive? Do they fit your criteria? They could not be said to have a "stand alone intelligence" by any current definition of intelligence and yet they are biological and probably much closer to being alive than a calculator.