What differentiates the living from the non-living?

Mattius_

What physical property separates the two?

amadeus

That is a very interesting question, as any attempt to answer it using logic ends up with the conclusion that either everything is alive, including stones, or everything is dead, including ourselves. That can only mean one thing: "life" is a fundamental property of the universe and as such can't be reduced to anything more fundamental, not even physics.

FZ+

Or that life is a subjective, relativist value.

selfAdjoint

Originally posted by Mattius_
What physical property separates the two?

For a multicellular metazoan, it is that the collective cellular processes still work. This automatically means that such an organism dies in some parts before others (cf. "brain death"), but once the major processes fail, the others will eventually fail too.

zoobyshoe

Doing my best to evade trying to
define "life" I would say that
what distinguishes that which is
alive from that which is dead for
me is that that which is alive
must be engaged to some
extent in the attempt to improve
or elaborate upon it's status quo.

That which is dead no longer exerts any effort of any kind on
its own behalf and is at the
mercy of any force that acts upon
it.

It is by virtue of this that I
would never consider rocks, or
minerals, or individual elements
to be possessed of life.

Pirwzwhomper

Well, since all "living things" are composed of elements, then perhaps life is a property related to complexity. After all, a cell is basically a very complex system of interactions and reactions. Of course, the cell is not a closed system, and a certain amount of interactions and reactions between it and its environment must take place. Maybe after a system becomes complex enough and parts of the system are dedicated to maintaining the system's continuity by interacting with and reacting to its environment, then it could be considered alive. But then, this is only my humble opinion.

Opinion

Originally posted by Mattius_
What physical property separates the two?

Breath.

FZ+

Keep that heart-lung machine away from me!

Arggg! Attack of the undead fishies...

*heusdens*

Originally posted by zoobyshoe
Doing my best to evade trying to
define "life" I would say that
what distinguishes that which is
alive from that which is dead for
me is that that which is alive
must be engaged to some
extent in the attempt to improve
or elaborate upon it's status quo.

That which is dead no longer exerts any effort of any kind on
its own behalf and is at the
mercy of any force that acts upon
it.

It is by virtue of this that I
would never consider rocks, or
minerals, or individual elements
to be possessed of life.

This is a good start.

But there is more.

Life als is able of reproducing itself, in more or less the same form.

And life distinguishes itself from the environment.

And life needs to take in sources of energy to sustain itself, it needs a form of metabolism.

zoobyshoe

Originally posted by heusdens
Life als is able of reproducing itself, in more or less the same form.

And life distinguishes itself from the environment.

And life needs to take in sources of energy to sustain itself, it needs a form of metabolism.

I agree with all except the first.
The mule, I beieve is is, which is
a cross between a donkey and a
horse, I believe it is, is not able to reproduce.

Likewise it seems resonable to
propose that throughout evolution
lifeforms came to be that were not
able to reproduce, and these indi-
viduals lineage died with them.
Before these indiiduals died, how-
ever, they were alive.

amadeus

Originally posted by heusdens
Life also is able of reproducing itself, in more or less the same form.

So does a computer virus. Which is why they are called 'virus'. Are computer viruses alive?

And life distinguishes itself from the environment.

Yes, living beings are different from the environment by virtue of being alive. Like any fundamental principle, such as 'matter', 'space', 'time', life can only be defined tautologically.

And life needs to take in sources of energy to sustain itself, it needs a form of metabolism.

So does my car.

What stands in the way of accepting life as a fundamental, irreduceable principle of the universe?

zoobyshoe

Amadeus,

Your car does not sustain itself.
It can never make any effort on
it's own behalf to do so. It
cannot even desire to make such
an effort.

Nohing your car takes in goes to
sustaining it in it's present
state. All of its parts start to
be acted upon by environmental
agents as soon as they are made.
It's downhill from there: no
growth, no healing.

A car cannot be used as an example
of something that sustains itself
by taking in nutrients.

Another God

Douglas Adams at Digital Biota 2

"I was thinking about this earlier today when Larry Yaeger was talking about ‘what is life?’ and mentioned at the end something I didn’t know, about a special field of handwriting recognition. The following strange thought went through my mind: that trying to figure out what is life and what isn’t and where the boundary is has an interesting relationship with how you recognise handwriting. We all know, when presented with any particular entity, whether it’s a bit of mould from the fridge or whatever; we instinctively know when something is an example of life and when it isn’t. But it turns out to be tremendously hard exactly to define it. I remember once, a long time ago, needing a definition of life for a speech I was giving. Assuming there was a simple one and looking around the Internet, I was astonished at how diverse the definitions were and how very, very detailed each one had to be in order to include ‘this’ but not include ‘that’. If you think about it, a collection that includes a fruit fly and Richard Dawkins and the Great Barrier Reef is an awkward set of objects to try and compare. When we try and figure out what the rules are that we are looking for, trying to find a rule that’s self-evidently true, that turns out to be very, very hard.

Compare this with the business of recognising whether something is an A or a B or a C. It’s a similar kind of process, but it’s also a very, very different process, because you may say of something that you’re ‘not quite certain whether it counts as life or not life, it’s kind of there on the edge isn’t it, it’s probably a very low example of what you might call life, it’s maybe just about alive or maybe it isn’t’. Or maybe you might say about something that’s an example of Digital life, ‘does that count as being alive?’ Is it something, to coin someone’s earlier phrase, that’ll go squish if you step on it? Think about the controversial Gaia hypothesis; people say ‘is the planet alive?’, ‘is the ecosphere alive or not?’ In the end it depends on how you define such things.

Compare that with handwriting recognition. In the end you are trying to say “is this an A or is it a B?” People write As and Bs in many different ways; floridly, sloppily or whatever. It’s no good saying ‘well, it’s sort of A-ish but there’s a bit of B in there’, because you can’t write the word ‘apple’ with such a thing. It is either an A or a B. How do you judge? If you’re doing handwriting recognition, what you are trying to do is not to assess the relative degrees of A-ness or B-ness of the letter, but trying to define the intention of the person who wrote it. It’s very clear in the end—is it an A or a B?—ah! it’s an A, because the person writing it was writing the word apple and that’s clearly what it means. So, in the end, in the absence of an intentional creator, you cannot say what life is, because it simply depends on what set of definitions you include in your overall definition. Without a god, life is only a matter of opinion."

Life, seemingly like all things in our universe, is a phenomenon named by humans, which isn't bounded by a nice neat couple of lines of demarcation. Life, is a part of everything else which does something neat, but nothing which is unique nor removed from everything else which happens.

Just like us humans like to have these neatly defined colours : Red, blue, green, yellow etc... when we find out what colour actually is, we quickly realise that there is no neat defined boundary of where Blue stops, and green starts...there is just a continuum. A morphing from one thing into another.

Life, is a chemical reaction...it just happens to be a type which may become increasigly complex and self-propogating, so when seen in its most extreme form (Eukaryotes) it is easy to define. When u follow this easily defined 'life' back to its origins though...it becomes incresingly hard to find that magical line of demarcation.

The same thing is apparent with 'What is human?' Whether u mean evolutionarily (it is obvious what is human now, but backwards in evolutionary time, the demarcating lines become more blurred, and no line is apparent), or whether u mean individually (Is a Zygote a human, an embryo, a fetus, a baby etc?) The lines simply do not exist.

People need to start understanding this, or else find a real way to define these concepts (ie: Find God and ask him to tell us the lines.)

Another interesting way of targetting this question is: What seperates a living organism, from a dead version of that same organism.
ie: Poison someone, and figure out what it is precisely that makes them dead as opposed to the non poisoned person.
OR
What is the difference between viable and non-viable bacteria?

zoobyshoe

The heading of the thread seemed
targeted at discussing the polarities: whats the difference
between that which we definitely
consider alive, and that which
we definitely consider dead. This
is a different question than "what
is life?" I didn't observe anyone
getting confused about the parameters.

Another God

OK then, how about: "Degrees of complexity"

Arawn

Life is Universe's way to increase entropy faster. Living beings actively try to decrease entropy (increase order) locally, at least by sustaining their own bodies. More complex organisms, for example we humans, also attempt to decrease entropy at our surroundings (buildings, cleaning). But all this has only local effect, and the entropy of the system as a whole actually increases; the more we increase order locally, the bigger is the entropy increase in the whole system.

So living beings have a tendency to decrease entropy locally.

zoobyshoe

Originally posted by Another God
OK then, how about: "Degrees of complexity"

The tone of that post was frankly
exploratory; speculative, no
assertions were made.

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Mattius_	What differentiates the living from the non-living? Tweet What physical property separates the two?

amadeus	That is a very interesting question, as any attempt to answer it using logic ends up with the conclusion that either everything is alive, including stones, or everything is dead, including ourselves. That can only mean one thing: "life" is a fundamental property of the universe and as such can't be reduced to anything more fundamental, not even physics.

zoobyshoe	The heading of the thread seemed targeted at discussing the polarities: whats the difference between that which we definitely consider alive, and that which we definitely consider dead. This is a different question than "what is life?" I didn't observe anyone getting confused about the parameters.

Another God Recognitions: Staff Emeritus	OK then, how about: "Degrees of complexity"