[nikk]

i am really confused about the perfect definition of 'life'. i was discussing about this with my friend at school i attempted to define it
i said ,'' life is a systematic and specific conglomeration of certain inorganic substances which form a
'system' [an organism] which gets the ability to perform certain processes to maintain the 'system'. ''


am i right with my definition?
thank you

[granpa]

fire can grow and maintain itself but isnt alive.

the ability to evolve is essential

[Mr Skeptic]

I have a degree in biology, but I don't know what life is either. Each definition has its flaws, especially if we aren't restricting it to biological Earth life. At the end of the day, it is just a definition we make up and things fit it or they don't. But it is very educational to try. To start off, decide which things you want to define as alive or whether you want to restrict your definition. Earth life, viruses (which can't reproduce without a living cell), alien organic life, alien inorganic life, mechanical sentient robots, which of these are alive and which of these are not, or which of these do you want to ignore for the sake of simplicity?

These concepts might help: life must at some point be able to reproduce (else it would not exist), there needs to be a boundary between the living thing and its environment (for non-virus Earth life, that is a phospholipid bilayer, much the same thing as a soap bubble but more stable), the ability to maintain homeostasis (though again viruses are an exception).

[Andeh]

most definitions (especially ones in a less-fundemental feild like biology) are completely arbitrary--a reflection of the human desire for order, where often there isnt. This is because there are always fringes...we group an evolutionary line into seperate species, but of course there are intermediate stages.

Do you consider viruses alive? and even more extreme, do you consider replicating molucules alive, which can "reproduce", compete, and mutute. defining life is like saying that at some point abiotic became biotic--and materialistically, that never happened, since biotic and abiotic are just labels. All that happened was that the "proto-organism" "learned" some new chemical tricks.

In short, you can't define life. But like mr skeptic said, it's education to try, since it makes us try to understand it better.
try writing that for the answer to that question on a biology test!!

[Essay]

nikk, on 1 December 2011 - 05:45 PM, said:

i am really confused about the perfect definition of 'life'. i was discussing about this with my friend at school i attempted to define it
i said ,'' life is a systematic and specific conglomeration of certain inorganic substances which form a
'system' [an organism] which gets the ability to perform certain processes to maintain the 'system'. ''


am i right with my definition?
thank you

Life is like pornography; I think I know it when I see it....

I like your point about a "system" but even "a system" can be somewhat arbitrarily defined.
...and with such a definition, things like climate, soil, and Gaia might qualify as life, as these "things" are organic/inorganic systems that evolve, or at least co-evolve. Hmmmm, does anything "evolve" or must everything necessarily co-evolve?

~

[Ophiolite]

nikk, about five or six years ago at an international conference on exobiology the participants were asked to offer their definition of life. Around one hundred differing definitions were offered. Perhaps once we have encountered other lifeforms and noted their similarities and differences to our own the definition will become easier. (It will never be perfect: this is science.) On the other hand, if some life is so different from us we may not be able to recognise it.

[questionposter]

I don't think there can be a concrete definition of life. What about complex artificial intelligence? It doesn't evolve, it doesn't grow, but it could still process the same information as other living things.

[michel123456]

That's amusing.
Mathematics should be used to answer this question instead of words.

[questionposter]

michel123456, on 15 January 2012 - 06:07 PM, said:

That's amusing.
Mathematics should be used to answer this question instead of words.

Math isn't anything on its own, we assign what it means with words.

[CharonY]

Quote

On the other hand, if some life is so different from us we may not be able to recognise it.

This is most certainly true. However, in my mind (as a biologist) "life" is just a convenient classification. In a naive approach I would think that If we discovered a mystery particle, for instance, one might classify it as life when it becomes necessary to invoke biological methodologies or theoretical frameworks to explain some of its properties.

[michel123456]

questionposter, on 15 January 2012 - 06:14 PM, said:

Math isn't anything on its own, we assign what it means with words.

Oh. I thought mathematics could explain everything (sarcasm).