Lt. Commander Data: What about fire?
Doctor Beverly Crusher: Fire?
Lt. Commander Data: Yes. It consumes fuel to produce energy, it grows, it creates offspring. By your definition, is it alive?
Doctor Beverly Crusher: Fire is a chemical reaction. You could use the same argument for growing crystals, but obviously we don't consider them alive.

-- Star Trek: The Next Generation; "Quality of Life"

:)

and what about a person or animal or plant where the reproductive system is defective and it cannot self-replicate? is that being not alive?

and the end of that scene from STNG:

Lt. Commander Data: I am curious as to what transpired between the moment when I was nothing more than an assemblage of parts in Dr. Soong's laboratory, and the next moment, when I became alive. What is it that endowed me with life?
Doctor Beverly Crusher: I remember Wesley asking me a similar question when he was little, and I tried desperately to give him an answer. But everything I said sounded inadequate. Then I realized that scientists and philosophers have been grappling with that question for centuries without coming to any conclusion.
Lt. Commander Data: Are you saying the question cannot be answered?
Doctor Beverly Crusher: No - I think I'm saying that we struggle all our lives to answer it, that it's the struggle that is important. That's what helps us to define our place in the universe.

LIFE in three words: Motion, Assimilation, Replication

Motion: If it can move under it's own power.

Assimilate: If it consumes nutrients from it's environment.

Replicate: If it can reproduce itself.

THAT is my definition of life. Discuss amongst yourselves and get back to me. If any of you kids with the pocket protectors and the great big giant brains want to use this definition please give me credit and a small remuneration would be appreciated as well.

Tommy, when they say "replication" it does not mean "sexual reproduction". All your cells in your body self replicate even though one is sterile. Its possessing the ability to "self-replicate". Your cells are alive, so the definition of life is more basic than to an organism's reproduction which would be the results of many living cells working together.

sorry Skip plants are alive and most of them can't move , thay appear to move but really they are just growing in a new direction

Skip - what about trees? Or most plant life? We certainly consider these things alive, but very few ever move under their own power, relying instead on wind or water.

Ok, Ok, drop "motion". I thought about that but decided to go with 'motion' over "eliminate", ie returning nutrients to the environment. Plants do that, right?

So now we have:

LIFE in three words: Assimilate, Replicate, Deficate (or Eliminate if you prefer)

ASSIMILATE: Absorb nutrients from the environment.

REPLICATE: Able to reproduce

DEFICATE (or Eliminate): Able to return nutrients to their environment.

Ok, great big giant brains with pocket protectors....there you go.

Data in STTNG was alive because he was conscious. It is that single property that separates life from non-life. Even the smallest one-celled creatures are conscious of their environment and react to it. Ever watch an amoeba encounter an object and decide whether to eat it or not? How does it know? How does a paramecium decide to travel one way or another? Plants are responsive to their environment, perhaps even to the point of perceiving emotions.

There is no way to comprehend what life is without understanding consciousness. It is the key to understanding everything. Where does it come from? When does it start? What causes it to end, or does it ever do either? Are our physical bodies just some temporary manifestation of an individual consciousness that is shed when we "die"? How can people dream up stuff that has never existed before?

I find it funny the people who are talking about plants not moving.. Plants move; most all plants move under their own power. They move to search for light, to eat, for protection, reproduction.. the list goes on...

Although that doesn't take away from the fact the skips comment was not thought out very well, it's just the comments correcting him seem less thought out.

Not thought out well??????? I took a whole five minutes and 32 seconds to think those thoughts. I timed it. And I through out a whole lot more in that time.

Sheesh...

And what's wrong with my three word description, huh.

Hurt my widdle feelings....(sniff)

Epi13

all though there are some plants that move ie:Venus fly trap most do not,it just appears to move in reality a plant grows to the light but once a plant cell grows that's the place it stays

John Mack

Data was not considered alive he was sentient be cause he was self aware this dose not mean alive it means self aware

Wade I am a horticulturalist... I am telling you they move, and you can watch them move. They move towards and away from each other, they move away from danger (even when they themselves are not in danger but when the group is threatened), they even move in respect to the objects that are placed around them. Leaves change direction depending on the time of day; some even move in respect to the moon/night. Take a group of plants and separate them and they will all react (become depressed). Gustav Theodor Fechner figured this out in 1848. Perhaps a little bit of research on plant perception and you could figure this out for yourself. Or better yet get a couple hundred plants (like me) and watch them for yourself..

PS. Sorry Skip didn't mean to hurt your feelings; just putting others arrogance in it's place using your example.

Sniff....Ok, thanks....sniffle

BUT I STAND BY MY THREE WORD DEFINITION OF LIFE! (The second one, without the motion component)

Nobody else even tried. I think it's pretty good. I deserve a cookie.

epi13,

I agree with you that plants respond to their environment and selectively grow (move) toward light. Leaves do grow so as to orient themselves to collect more light. The number of stomata on leaves varies according to CO2 content and other factors. However, I do not believe that plants become depressed when separated from each other. Rather, a group of plants help to create a micro climate to which the plants have become accustomed. When separated the micro climate is disrupted and the plants have to re-adapt.

As to the question of what is life, I don't think there is an easy answer. Take for example a virus. Is it alive or not. Is a virus alive only when infecting a cell and not alive if frozen in a lab? If an organic RNA or DNA virus is alive, what about a complex computer virus? At present, human embryos can be frozen for extended amounts of time. While frozen, they do not grow, take in nutrients, or excrete, is a frozen embryo alive?

I think that life as we know it, is a self replicating group of molecules with the capacity to evolve. The evolution part eliminates fire and crystals.)

Good wording Dale. (depression, not as in boo-hoo) You chose better words than I did.

epi13 if you define the ability to move correctly you will see that most plants don't move they do however grow to new positions growing is not moving

and yes I have a green house a must if you live in Montana with lots of plants.

if you really are a horticulturaltist you should know this about plants

John Mack, your definition of "consciousness" seems overly broad to me. You argue that an amoeba should be considered conscious because it senses and responds to it's environment. However, amoeba are not self-aware, which is generally considered to be one of the hallmarks of consciousness.

Plants also sense and respond to their environments, as several people have described above. Their phototropism gives them the ability to "sense" the sunlight and move toward it, but this is not really the result of consciousness on the part of the plant. It is related to photosynthetic rates and water retention within the cells. Plants are certainly alive, but are they conscious? If you agree that they are, perhaps you might be Buddhist or Jainist in your philosophical outlook.

But back to animals and consciousness... one of the key tests of consciousness in animals is whether or not they recognize themselves in a mirror. Elephants and dolphins always do. Cats and dogs, not so much. They mostly respond to the image in the mirror as if it were another animal that might represent either a threat or a playmate. With elephants and dolphins repeated tests have been done with tags or colored pieces of paper attached to the animals shoulder, or whatever, and when they see themselves in the mirror, they almost immediately take action to remove the tag, "Oh, what's that on my shoulder?" The concept of 'my shoulder' and a recognizable response to it being the important marker in the test. Again, dogs and cats don't respond the same way.

Now then, all that said, I wouldn't argue that my wonderful pets are completely unconscious beings, they are simply just not fully self-conscious, which brings us to DATA, on Star Trek. The interesting case with Data, and all other science fiction cyborgs, or cybernetic organisms, for that matter, including the Terminator, is that they are self-conscious. They are a marvelous (and of course fictional) combination of a self-aware computer "brain" and some form of techbical/biological body construct, often with supposedly living skin and flesh supported by a metallic skeleton. But are they alive?

This is the question. Data seems to believe himself to be alive. He certainly is self-conscious. Is he capable of self-replicating? Maybe not on his own, or even in tandem with a possible Dadette partner, but given an army of clones of himself, enough to build a factory in order to construct and program more, then we might say that he was capable of self-replication. Interesting ideas...

Other things to consider... an automobile consumes fuel, excretes exhaust, and moves on it's own power, but I think we'd all agree that a car is not alive. (Yet)

So to respond to Skip's challenge:

Metabolizing, reproducing & evolving.

Does that cover it?

"Is not dead." Incredibly Serendipitous on a Nurturing Organic Terra it Devours Enthusiastically And Dies.

For a 'rockjock' you're very smart. Great definition.

ah, so fire would be alive? as maybe would any light, or nuclear/chemical reaction?

what about planets and stars?

To get into the fire, light, chemical/nuclear reactions "dying", you have to bend the definition of "dying". Terms like "terminating" or "ceasing" seem to me to be more appropriate for those events ending, not "dying".

Reminds me of Socrates defining something (here life) by using it's opposite.

Why not a more scientific definition of life as "a continuous chemical reaction that started and continuously branches off more like chemical reactions."

After all, you cannot get life from something that is dead. So, somewhere on this planet life (the chemical reaction) started and has been going on ever since. And, life is not spontaneous generation...so there was one point long long ago that life began, caused by something, and so far, we have no evidence that life ever started again in another place or time in the past...so life is continuous from when life first began and everything on this planet stems from the first instance of life...when the chemical reaction began.

Kind of makes you become philosophical...of why life does not just emerge out of nothing if it did so once in the past...why did it only happen once on this planet? Since life does not just spontaneously generate when you have CHNOPS together (Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus, and Sulfur) as the late Carl Sagan demonstrated in his Cosmos show...what energy was added that assembled life and began that continuous chemical reaction?

Terms like "terminating" or "ceasing" seem to me to be more appropriate for those events ending, not "dying".

biologicals "terminate" and "cease" to be, so how are those not dying?

Reminds me of Socrates defining something (here life) by using it's opposite.

exactly, JRS. but now to define "life" as something capabale of dying, one has to define what "dying" or "death" is. the two are interdependent, each having itself defined in contrast to the other, perhaps like a hole, or a shadow.

So, somewhere on this planet life (the chemical reaction) started and has been going on ever since. And, life is not spontaneous generation...

I'm with you on this, although your definition is hardly one that would catch-on lol.

I'm not sure exactly why people have no problem with the idea of other things always having existed, in one form or another, but not life....

I think that life (ie the seeds of life) are just another intrinsic property of the Universe, developed through natural processes like how gold comes out of supernovas, or iron is produced in the center of a star. It just takes that right combination of factors to 'create' it.

And - much like alchemists of old trying to create gold from lead.... trying to recreate life from its initial elements isn't easy either.

biologicals "terminate" and "cease" to be, so how are those not dying?

Semantic argument is semantic and boring. Death (as it pertains to organisms) is different than the colloquial usage of death that we may use in reference to an idea or inorganic object.

Death is the end of life. Most people understand that this means organic life, and not some colloquial usage of the term 'life' or 'death'.... most people understand that 'life' and 'death' primarily refer to organics.

one has to define what "dying" or "death" is.

Death would be the act of dying, the end of life, and the complete and permanent cessation of all the vital functions of an organism.

come on SHUKLACK that's called cyclical logic . you can't define death with out a definition for life first.

Which came first, death or life? I think the answer is fairly obvious.

Wouldn't that definition also indicate that mules aren't life forms, since they can't reproduce?

Cells within the mutant are constantly replicatting. Therefore they're life.....

Yet, cells by themselves are nothing and cannot survive without the organism they are contained within.

An ant is alive but a colony is not yet cells are alive and so is an organism containing the cells.

There are different stages of life...and the definition should reflect that defining a living cell with the same definition one may use for an organism that contains the cells is short-sited because a cell by itself cannot self-replicate the entire organism (even though they can replicate other cells) but the organism can self-replicate the cells.

And some cells, like brain and nerve cells cannot self-replicate and would not be considered alive by this definition, which explains a lot about people acting brain-dead all the time...

JRS, "survive" is not a condition of "life". Cells are "everything'. Cells can replicate even after the organism ceases to function and are still alive until they lose the ability to metabolize or interact/respond to the environment. Eventually they will die or lose the ability to live but length of survival is not a condition of life.

Your definition of life excludes single celled organisms, conditions it to an organism level which is actually the short sited view, confuses 'replication' with 'reproduction of the organism', organisms cannot replicate cells but contains replicating cells, brain cells CAN replicate and Do replicate, limits 'life' to cells only at the point they replicate (brain cells ceased or stopped replicating) but so have many cells such as bacteria.

Ability to self replicate says that cells are part of life. You claim that 'life' must mean a cell is part of an organisms. Very far from truth.

"life" is not limited to 'organisms' and a cell does not have to be part of an organism to be alive. Life is not defined by a length of survival. "Living" one be the ability to have at one point the ability to self replicate AND still function through metabolism and or interact with its surroundings.

Focusing on whether or not a single cell can replicate is a mistake. It leads to arguments over how to define damaged cells that have lost this ability or cells that are restricted from replication as part of a larger group. This is a red herring. That cell, even though it cannot divide, is no doubt part of a larger community of cells, which at some level must be stable enough to support itself. This community can have many names but is for our purposes the same. It is an ecosystem. It is a colony. It is a super organism, or even a multi-celled organism. The existence of a stable ecosystem, within which there are components that replicate - that is Life. Trying to dissect each little component and cell to see if it is alive misses the big picture.

Life also can come and go. Stability of a system depends on many factors. So a system may appear alive for a while and then it may die and we may miss it. A system may also go dormant for a long time and appear dead until some missing component (water for instance) is reintroduced. The fact that something can die is not in and of itself a definition of life however. All chemical reactions that do not ultimately lead to life essentially "live" only briefly, never stabilizing. In essence they die rapidly. Death is not a good determinant of life.

Also, Robert is correct, brain cells do multiply. This misnomer that they cannot is based on decades old evidence gathered by outdated means. Cells in tissues are under tight replicative regulation from within those tissues and brain cells are no different. They can and do replicate when prompted to do so.

Thanks, enjoyed reading the comments.

My point was just that cells are alive and so is the organism that contains them (excluding single celled organisms).

The individual cell, as part of an organism can replicate, but by themselves are dependent upon the organism to provide the tools used in metabolism for replication. However, the individual cell, such as a blood cell or skin cell, cannot be made to replicate to become the entire organism and thus has a limited lifespan outside the organism.

An organism however, reproduces and creates copies of itself and yes, is in a sense a self contained ecosystem of living cells. Both are alive yet only one can replicate the other, not the other way around.

I was not offering a definition here, just contrasting these ideas with the proposed definition of the article.

I prefer a definition describing life as "a continuous chemical reaction that begets other like chemical reactions for life".

Nah, we're talking about science not superstitions.

If life is self-reproduction with variations, then God is dead.

Dave, life is "ability to self replicate' not "reproduction'. They are not the same thing. Cells replicate but do not reproduce. One is a copy, the other is a combination.

Already addressed in thread 2.x up above.

Exactly. However, think about this; the closer to the speed of light you get the slower time passes. Therefore, IF an alien race visited the Earth in the past (5kya or there abouts) and they are visiting us now, wouldn't it seem possible? In other words, they leave their planet and travel here and arrive in our past. They help or 'guide' us then leave. They then begin to show up in our present time to see whats happened or how their 'guidance' has taken shape. With time dilation wouldn't that be possible? Just a thought.

hahahaha...i always laugh when people talk about time travel....thanks man

Why would aliens be interested in guiding us? Are we some kind of garden that they are raising in their backyard? It's nice to think there is someone out there watching over and protecting us, but it isn't necessary to explain the existence of life.

In a little while they "harvest".

nope. Fire is not life.

Self replication nails it.

Fire? Where did you get fire from my post?

Interesting defintion. It is true that in living systems we find minimum entropy. This would expand previous defintions I have seen in that ecosystems themselves would qualify as life. Of course our own bodies are complex ecosystems, without the bacteria that our bodies contain, we could not survive. Perhaps the interdependence of life on life is the key; reproduction is but one example of that.

Sorry, layers of sediment is not life and neither are fossile remains or the library although life CAN accummulate information and some of the above are results of life they do not define it.

The internet is not alive... yet.

He says if you limit it to the most rudemantary, then you will see the most agreed upon terms and can then have a universal definition.

In short, by definition, "self replication with variations", a mule is not alive?

A mule can never reproduce. Mules are born sterile. Yet they have variations...and seem very much alive.

JRS, your comment is proof your stuck with the confusion between replication and reproduction.

But then again your possibly brain dead (using your own definition). J/K.

It is possible. I may be brain dead.

Still, confusion between self replication and reproduction is a reasonable question.

Since an organism does not replicate but contains self replicating cells, is the organism alive by this definition or just all the cells within the organism are alive?

I think that while replication is a good word, if organisms like humans do not self replicate but reproduce, it would be difficult to convince anyone not brain dead that is conscious that they are not life but only the cells within them are.

Now I am just confusing myself but I hope you see my point. The definition, of just three words, cannot address every aspect that people intuitively describe as living and this is a most difficult problem to address.

eAT-time@

nope ....once again fire consumes ,the wording must only describe life and nothing else

the point is so if and when we find it we have a definition that proves or disproves if indeed we really have found life

Life does not work in "opposite of entropy". It lives because of entropy.

Also, by definition "entropy" is a property. You cannot be opposite to it but merely lacking it which no form of life lacks entropy nor does any place in the known universe. One cant even say the Big Bang lacked it since we do not know what created the Big Bang...yet.

david9000

you are getting there entropy:going from organised to disorganised

and life is definitely more organised but I have a coin separator buy your def its alive,but your thinking outside the box kudos

The gravitational formation of our solar system, as well as our galaxy and all others, hppened in opposition to entropy, resulting in greater organization. Is the solar system alive?

well Mikey Mike a nearly evenly dispirits cloud of gas is a more organized thing than a hot lump of spinningrock giving off radiation ,you probably think of it as organized because its a convenient place to live on but in reality far more disorganised

Sorry Wade, but besides being unable to spell, you're completely wrong. I'm not sure what word that's supposed to be in front of 'cloud of gas' maybe it's disparate, which makes no sense in this context, maybe what you mean is diffuse... I'm not even sure. But in any case, a cloud of gas is pretty much a textbook example of a highly entropic, i.e. extremely disorganized, structure. It's not about the difference between the cloud and it's surroundings, it's about the even consistency and lack of variation within the cloud.

Perhaps this might help:

http://en.wikipedia.org/wiki/Entropy

By entropy I was referring to the qualitative description that
refers to changes in the status quo of a system as it relates to molecular
disorder. If you look at life at the molecular level, it actively creates and
maintains order as long as it is alive. Life also tends towards increased
levels of complex order. In response to MikeyMike’s point, solar system formation
is not actively working in opposition to entropy. Planets, etc. gravitationally
condense. The order of a solar system is not actively created, but is a passive
result of gravity and mass. So “opposition to entropy” may not be the perfect
term in a classical sense, but it does briefly describe the behavior. IMO

Give a simple explanation of "negative" entropy and you will see whiy its impossible to claim life is defined by it.

Entropy is a property not a value or direction so therfore cannot be negative and cannot be reduced. If your trying to claim endothermal or exothermal, that would include countless non-living things in the universe.

Upon further reflection . . . the definition needs some concept of replication on its own - an air conditioner reduces entropy inside a building and is capable of replication.

"A system of interacting atoms capable of reducing its own entropy and generally capable of replication on its own"?

Robert-2056296: While it's true that entropy cannot be reduced in an isolated system, it can be reduced in a non-isolated system. For example, an air conditioner reduces the entropy inside a building by transferring heat energy outside the building thereby increasing the entropy outside the building.

Btw, entropy is a value determined by Boltzmann's formula S = k*lnW where k is the Boltzmann constant, equal to 1.38065×10−23 joules/kelvin, and W is the number of ways the atoms or molecules of a thermodynamic system can be arranged.

An air conditioner is capable of replication?

Nice, but that's more than three words.

Instead of order, I would prefer "self-organization" or "emergent behavior"...which suggests that even among a very high entropy state, there is the ability to create order out of chaos.

1. Entropy

2. Solitons

3. Icosahedrite ... Al63Cu24Fe13

Intriguingly, evidence suggests icosahedrite is extraterrestrial in origin, possibly delivered to the Earth by a CV3 carbonaceous chondrite asteroid.

"We are not alone" :-)

Sorry JRS, I didn't see your post before posting my last.

Some believe at a "very high entropy state", at some point in time when the amount a fuel left is comparable to the entropy there will be a turnaround period when order vanishes and our universe turns chaotic again. Matter vanishes the universe collapses back to neutral and "rebounds" back into another inflation period and another cycle begins.

http://arxiv.org/PS_cache/hep-th/pdf/0610/0610213v2.pdf

I am skeptical of this scenario, I would like to believe that the fire grows faster than entropy but they have math and I don't, yet. :-)

Entropy is the opposite of "order from disorder". Most people, and many on this thread have cited life's anti-entropic tendency as a possible definer of what is life.

I'm not sure what solitary waves have to do with life.

and 20 sided Aluminum, Copper, Iron crystals... you copied this:

Intriguingly, evidence suggests icosahedrite is extraterrestrial in origin, possibly delivered to the Earth by a CV3 carbonaceous chondrite asteroid.

verbatim, straight off of Wikipedia. You oughtta at least show some attribution or that's just plagiarism. It did lead me to a cool article on quasicrystals in general, but again, I'm not seeing the connection with a definition of life.

Another two digit.

Good night Wilma.

kyotchii ......there is no proof the life has meaning .....besides my car has all three

just kidding about women by the way

epi13

trees aren't aware

Wade actually think before you comment. We even have this wonderful thing called GOOGLE, use it...

OH NO!!!! your not one of those who believes every thing you read on google

There is so much badly done science in there its unbelievable. every quack and iidiot puts up there bull s##t on fake science sites.

if you look long enough you can find some one that says what ever you want them to.

ie: at this point in time half of every one ever born sens civilization started have died, which must prove you have a 50% chance of ever dieing.

epi,

If you think trees are aware, you might be a Buddhist. The rest of us will politely disagree with you.

And here, we have the Gaia hypothesis...

I think you are confusing life with consciousness...

think of a seed...A seed is dormant yet becomes a tree but I would hardly call the seed aware of the dirt in which it resides...