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Author Topic:   Definition of Life
Jon
Inactive Member


Message 1 of 77 (333651)
07-20-2006 8:32 AM


I was reading a book: Galileo, Darwin, and Hawking: The Interplay of Science, Reason, and Religion. (Phil Dowe), which says, in regards to the formation of carbon atoms after the Big Bang:

...[T]he entire process is so improbable that it is overwhelmingly unlikely that there can have been enough carbon produced since the Big Bang for carbon-based life to have evolved. The fact remains however, that sufficient carbon was produced. How can we explain this improbable good fortune?
...
It's hard to exaggerate how fortuitous this is. If the energy levels involved in this process had been any higher or lower there would be no carbon, and therefore no life in this universe.

(Dowe 149)

The rest of the chapter is tied up in finding various scientific and religious explanations as to how this "improbable" event could have occurred. The problem I am having here is the insistence that carbon is required for life. A Wikipedia article on Alternative Biochemistry makes it quite clear that there are other chemicals available from which life (given the proper conditions) could form.

This, however, brings up yet another problem in my brain. How is it that we (Earthlings only familiar with carbon-based life forms) can decide what other life forms would look like, or be made of? The Wikipedia article seems to say that the only chemicals in consideration are those which bear resemblance to the ones we know of for forming life (carbon, water, etc.). This is no surprise, as the Wikipedia article on Life seems to offer a definition very much fitting with our observances of life on our own planet. A view, which to me at least, seems rather self-centred--and as it's been shown since we first realized the Earth is not the centre of the Universe, such views can often be wrong.

I feel there must be a more general definition for life, which could incorporate all possibilities of complexity, self-replication, etc. that make life different from non-life. And if such a definition is not found, then it does become rather unlikely that we will ever find life elsewhere in the Universe--if, after all, we are to only regard things fitting our own self-centred view of life as life. And in such a case, is there any difference between life and non-life? Indeed, this would make us much less special in the galaxy (which would be better-fitting with the fact that we are also not at the centre of the Universe).

It is my opinion that life/non-life is a subjective differentiation that we make; and that there is nothing more special about life, than there is about non-life.

Is there anything scientific to show that there is something drastically different from life and non-life, other than more subjective lines drawn to separate one thing (existence) into two separate categories (life/non-life)?

Jon


In considering the Origin of Species, it is quite conceivable that a naturalist... might come to the conclusion that each species had not been independently created, but had descended, like varieties, from other species. - Charles Darwin On the Origin of Species

Replies to this message:
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Jon
Inactive Member


Message 4 of 77 (333776)
07-20-2006 3:56 PM
Reply to: Message 3 by Annafan
07-20-2006 9:07 AM


life maintains itself against the tendendy towards thermodynamic equilibrium.

Doesn't this "thermodynamic equilibrium" apply only to heat? I'm not sure if you're a Creationist or not, but they do have a tendency to apply thermodynamic laws to everything :rolleyes:.

Isn't it all just a matter of definition?

My point exactly. In which case, it doesn't make us much different than anything else out there. And if there is no different between life and non-life, then the chances of life arising elsewhere in the Universe become quite high!

However, I do realize the difference between me, and the desk I'm sitting at. I'm alive, the desk isn't. For this reason, I would have to guess that there is somehow an objective scientific way to determine whether or not something is alive; seeing as how there are so many different and unfamiliar ways things can come into living.

Jon


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Jon
Inactive Member


Message 14 of 77 (334189)
07-22-2006 12:43 AM
Reply to: Message 9 by RAZD
07-21-2006 7:41 PM


I do think that evolution-ability needs to be included in the definition -- the {proto-"ur"-life} needs to be able to {react\respond} to the surrounding input {environment} and {select\be selected} for fitness or it is just static growth (like a crystal).

But then, as pointed out by the link you provided in your first posting, mules would not be considered living, since they lack te ability to evolve (seeing as how they cannot even reproduce). Yet, to exclude something so obviously alive as a mule from the deffinition of life makes the deffinition a little useless.

Jon


This message is a reply to:
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Jon
Inactive Member


Message 16 of 77 (334207)
07-22-2006 6:48 AM
Reply to: Message 15 by nwr
07-22-2006 12:52 AM


Re: My tentative definition
Going back to the link in RAZD's first post then, what about fire? It follows the fuel line, which increases the probability that the processes will persist.

Is a fire alive?

Jon


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Jon
Inactive Member


Message 35 of 77 (335091)
07-25-2006 5:41 AM
Reply to: Message 25 by RAZD
07-22-2006 11:28 PM


And another problem with this definition is that life (as we know it) has {elements\sections} that synthesis all the parts of the cell, not just replicate their own molecules.

I might be misunderstanding this, but are you saying that the cell is the smallest unit of life (as we know it)? If this is the case, then we need only find the objective properties of a cell and decide if those are necessary for life. Or so it would seem, but there is something telling me it isn't quite that easy.

Jon


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Jon
Inactive Member


Message 37 of 77 (335215)
07-25-2006 3:31 PM
Reply to: Message 36 by PurpleYouko
07-25-2006 10:04 AM


Re: Seems a little narrow as definitions go
What about the possibility of non-carbon based life forms. how about the possibility of electrical lifeforms such as certain computer programs. Some are now getting very close to life. They reproduce, mutate and are largely subject to the same rules as other life forms.

But carbon-based doesn't necessarily have to be one of those parts of a cell that are necessary for life. These computer programs could be considered perhaps as an entire single cell, with each part of the program representing a certain required function of life.

I do find it difficult though to consider the computer program alive without a 'housing' for it. In that case, the entire computer might be considered alive, as it does have similar parts as a cell: takes in energy, converts it, stores it, uses it. The program has similar functions to DNA: copies itself, has occasional breakdowns/errors (crashes). Not only that, but it can also be similar to human thought at times.

But you see, the computer is not a large item made of many smaller ones. It is, as the cell, non-working when missing any of its parts (as apposed to multi-cellular organisms which can easily survive if one cell dies off). For this reason, I think a computer might be considered as one large cell, having all the parts determined necesary for life, thus being a live.

Jon


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Jon
Inactive Member


Message 62 of 77 (364497)
11-18-2006 3:46 AM
Reply to: Message 61 by 42
11-17-2006 2:14 AM


Re: a thin line?
Hmm. I don't think I agree. I feel much less stable than an atom. Wait? Don't atoms just change links here and there if I die, and then if I rot in the grave/riverbed? I mean, it would seem that my atoms are MUCH more durable than myself :( .

J0N


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