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The definition of life
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Space Station Commander ![]() ![]()
Joined: Mon May 31, 2004 9:47 pm
Posts: 827 Location: Yerushalayim (Jerusalem) - capital of Israel! ![]() |
Lourens wrote: I'd like to think of life as an opposing force to decay. Non-living things just are, and wither away over time. Living things keep repairing and recreating themselves. In more physical terms, perhaps we could say that something is alive if it comprises one or more processes that locally decrease entropy? I like that definition. Now how do we define "something"? _________________ “Once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return.” -Anonymous |
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Space Station Member ![]() ![]()
Joined: Mon Nov 29, 2004 1:04 pm
Posts: 257 Location: Norway ![]() |
SuperShuki wrote: I like that definition. Now how do we define "something"? It's what occupies the space between nothing and everything |
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Space Station Commander ![]() ![]()
Joined: Mon May 31, 2004 9:47 pm
Posts: 827 Location: Yerushalayim (Jerusalem) - capital of Israel! ![]() |
Lourens wrote: I'd like to think of life as an opposing force to decay. Non-living things just are, and wither away over time. Living things keep repairing and recreating themselves. In more physical terms, perhaps we could say that something is alive if it comprises one or more processes that locally decrease entropy? Perhaps I could enlarge on that definition. Life is the process of decreasing entropy. Entropy is movement towards chaos. Therefore life is the process of increasing order. Order is separation. Now apply this idea to all areas of life . . . _________________ “Once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return.” -Anonymous |
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Space Station Commander ![]() ![]()
Joined: Thu Oct 27, 2005 7:44 am
Posts: 707 Location: Haarlem, The Netherlands ![]() |
A thing (or object) is some subset of the universe that has a constant value for some property, and is surrounded by other subsets with different values for that property. I am a thing, because all of me has the property that it consists of cells containing my DNA, and none of the air, chair, floor, table and laptop that surround me have that property. A hole is a thing because it is an empty subset of the universe, surrounded by non-empty subsets.
I'm not sure that my definition of life is entirely correct yet though. Consider a computer that continuously sorts the numbers in its memory. That is a process that locally decreases entropy (of course the computer uses energy and produces heat, which makes total entropy increase, so it's not violating the laws of thermodynamics). Could we say that the computer is alive? One could argue that at some point the numbers will have been sorted, and no further increase in entropy occurs, so that there is no continuous decrease in entropy. But then, every once in a while there will be a cosmic particle that flies through the memory chips and flips a bit, and the order will be off, and it will be fixed again. Another, stronger argument would be that the computer hardware itself will still break down over time. So perhaps we could define a living thing as a thing that decreases (or keeps the same) entropy locally throughout all of itself? That would mean that my grandmother, with her prosthetic hip, isn't strictly alive, unless you consider her to end wherever the artificial joint begins, or unless she has the hip replaced whenever it wears out. That's not that unreasonable perhaps. There's another question of whether alive or dead is really a binary thing, or that we should take the rate of entropy decrease into account and introduce an ordinal scale. In vegetation science there is the concept of vitality, which describes how well a plant is doing. During a dry period for example, your lawn will turn yellow, and we can say that its vitality gets worse. It's not quite as alive as when it was nice and green and wet. It works in animals too: old people aren't as vital as young ones, and indeed their cells divide more slowly and damage is repaired less quickly. Conversely, a tumour can then be said to be more alive than the surrounding tissue, so much so that it starves it of resources and threatens its continuous existance. Is a slow-growing oak less alive than a fast-growing poplar? _________________ Say, can you feel the thunder in the air? Just like the moment ’fore it hits – then it’s everywhere What is this spell we’re under, do you care? The might to rise above it is now within your sphere Machinae Supremacy – Sid Icarus |
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Space Station Commander ![]() ![]()
Joined: Mon May 31, 2004 9:47 pm
Posts: 827 Location: Yerushalayim (Jerusalem) - capital of Israel! ![]() |
I'd say that the process that the computer is engaged in is a life- positive process. However, the computer itself isn't actually doing the process. The computer is a tool, just the same as a hammer in your hand. Therefore the life process that the computer is engaged in is actually an extention of its maker's and operator's life.
_________________ “Once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return.” -Anonymous |
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