[waserwill]

I would caution that we biologists study more than life, but also its environment! So, the abiotic conditions of soil, the function of enzymes (including proton pumps :D), and even the culture of humans (and dolphins and orangutans, etc.).

It's true that life can't really be defined by some essentialist statement (i.e. it has properties that neatly divide X from not-X), and the family resemblance approach works better (things like rabbits and viruses and oaks and cyanobacteria), even though it's not as satisfying. Mind, it's OK to just tell kids in biology classes a more convenient definition.

[ncmncm]

> "tell kids in biology classes a more convenient definition"

That is where you get conflict. Too simple? Too inclusive? Too not? But it's the only place where you need one that doesn't mention biologists.

"Life is a process that uses energy obtained from outside a boundary to reduce entropy inside it."

You have define entropy, then, which kids might not like much.

[waserwill]

These are good questions. I care most about these sorts of definitions when teaching, since they can orient students and describe what it is you are talking about. Some criteria I was taught about life:

> 1. Reproduces itself/making things similar to itself (sort of; viruses are on the periphery, prions...).

> 2. Metabolizes chemicals for energy

> 3. to grow, and as a result,

> 4. produces waste.

> 5. Reacts to stimuli in the environment.

> 6. Maintains homeostasis (reacts to stimuli in itself and keeps 1-5 going).

I really like these, because while they are wrong on some level, they are pedagogically useful: they orient students to what life does, what we can learn about it, and what sorts of data we can collect. Plus, it points towards both ecology and evolution.

Your definition is more encompassing in a way, so it better describes any life-form, but so encompassing that it also describes crystalization! (The parallels between life and crystals are admittedly interesting, especially when thinking about abiogenesis.)

Just from a practical perspective, I would rather start from those criteria than from physical chemistry and physics. Then, come exceptions and complications, which are great! Even when learning physics, I recall every other lecture beginning with, "Those assumptions we made were wrong. Instead, ..."

[tsegratis]

A 'self' reproducing or 'self' continuing process, via some kind of recursion -- reproduction, cloning or otherwise

Is that at all okay???

Note, I say 'self', since just as a cloud is transitory, so too, we live on food and can't divide us from it

Please note, I'm not saying this is right, I'm just having fun stabbing in the dark

[waserwill]

The definition I remember being taught early on includes that, so that's on the right track.

From memory: 1. Reproduces itself/making things similar to itself (sort of; viruses are on the periphery, prions...). 2. Metabolizes chemicals for energy 3. to grow, and as a result, 4. produces waste. 5. Reacts to stimuli in the environment. 6. Maintains homeostasis (reacts to stimuli in itself and keeps 1-5 going).

I'm probably forgetting some and there are exceptions to all of these. Notably, in interesting cases like at the inception of life, or at the periphery of life: viruses, parasites, potential extraterrestrial chemical systems, and arguably cultural systems. But those criteria are still convenient.

[tsegratis]

Nice list!