Tuesday, March 6, 2007
Contradictions in definitions
Most of the definitions are focused on differentiating between living material and non-living material. Some new ideas were proposed in the years between 1980 and 1990. It is still not clear whether computer software exists that could be considered as alive. Some computer software shows certain resemblances with living organisms. It is not difficult, in an algorithmic sense, to create software which fulfills some base criteria (growth, reproduction, reaction to environmental changes, etc.).
Consider an artificial environment with certain properties (for example, a system which is calling the processes with different input). If a process is able to solve the problem (respond with a correct output) within a given time limit, it can survive; otherwise, the process is deleted. If the process solves the problem before the other processes, it gets higher part from the computer resources. This is a very simple model of an environment in which life has been simulated. More sophisticated environments can also be created. Although in most of the simulations the systems collapse relatively quickly (for example, none of the processes are able to adapt and solve the given problem), it has not yet been formally proved that such an environment can not exist permanently. Such an environment would meet all the criteria of simple life definitions.
If ever such a theorem could be formally proved, it will be necessary to reconsider the definitions or admit that the computer world is a good approximation of the real one.
Consider an artificial environment with certain properties (for example, a system which is calling the processes with different input). If a process is able to solve the problem (respond with a correct output) within a given time limit, it can survive; otherwise, the process is deleted. If the process solves the problem before the other processes, it gets higher part from the computer resources. This is a very simple model of an environment in which life has been simulated. More sophisticated environments can also be created. Although in most of the simulations the systems collapse relatively quickly (for example, none of the processes are able to adapt and solve the given problem), it has not yet been formally proved that such an environment can not exist permanently. Such an environment would meet all the criteria of simple life definitions.
If ever such a theorem could be formally proved, it will be necessary to reconsider the definitions or admit that the computer world is a good approximation of the real one.
Notes on life(link only)
^ http://www.astrobio.net/news/article226
^ http://www.nbi.dk/~emmeche/cePubl/97e.defLife.v3f.html
^ http://forums.hypography.com/biology/6702-what-exactly-constitutes-life.html
^ http://www.ucmp.berkeley.edu/exhibits/historyoflife.php
^ http://www.scribd.com/doc/1569/Origin-of-Life-in-Universe
^ http://www.journals.royalsoc.ac.uk/openurl.asp?genre=article&id=doi:10.1098/rsif.2005.0045
External links
^ http://www.nbi.dk/~emmeche/cePubl/97e.defLife.v3f.html
^ http://forums.hypography.com/biology/6702-what-exactly-constitutes-life.html
^ http://www.ucmp.berkeley.edu/exhibits/historyoflife.php
^ http://www.scribd.com/doc/1569/Origin-of-Life-in-Universe
^ http://www.journals.royalsoc.ac.uk/openurl.asp?genre=article&id=doi:10.1098/rsif.2005.0045
External links
Origin of life
Although it cannot be pinpointed exactly, evidence suggests that life on Earth has existed for about 3.7 billion years .
There is no truly "standard" model for the origin of life, but most currently accepted scientific models build in one way or another on the following discoveries, which are listed roughly in order of postulated emergence:
Plausible pre-biotic conditions result in the creation of the basic small molecules of life. This was demonstrated in the Miller-Urey experiment.
Phospholipids spontaneously form lipid bilayers, the basic structure of a cell membrane.
Procedures for producing random RNA molecules can produce ribozymes, which are able to produce more of themselves under very specific conditions.
There are many different hypotheses regarding the path that might have been taken from simple organic molecules to protocells and metabolism. Many models fall into the "genes-first" category or the "metabolism-first" category, but a recent trend is the emergence of hybrid models that do not fit into either of these categories,Despite the length of scientist's current speculations, the origin of life remains as one of science's greatest mysteries.
There is no truly "standard" model for the origin of life, but most currently accepted scientific models build in one way or another on the following discoveries, which are listed roughly in order of postulated emergence:
Plausible pre-biotic conditions result in the creation of the basic small molecules of life. This was demonstrated in the Miller-Urey experiment.
Phospholipids spontaneously form lipid bilayers, the basic structure of a cell membrane.
Procedures for producing random RNA molecules can produce ribozymes, which are able to produce more of themselves under very specific conditions.
There are many different hypotheses regarding the path that might have been taken from simple organic molecules to protocells and metabolism. Many models fall into the "genes-first" category or the "metabolism-first" category, but a recent trend is the emergence of hybrid models that do not fit into either of these categories,Despite the length of scientist's current speculations, the origin of life remains as one of science's greatest mysteries.
Definitions of life
1. A characteristic state or mode of living; "social life"; "city life"; "real life"
2. The course of existence of an individual; the actions and events that occur in living;
"he hoped for a new life in Australia"; "he wanted to live his own life without interference
from others"
3. The experience of being alive; the course of human events and activities; "he could no longer cope with the complexities of life"
4. Animation: the condition of living or the state of being alive; "while there's life there's hope"; "life depends on many chemical and physical processes"
5. The period during which something is functional (as between birth and death); "the battery had a short life"; "he lived a long and happy life"
6. The period between birth and the present time; "I have known him all his life"
7. Liveliness: animation and energy in action or expression; "it was a heavy play and the actors tried in vain to give life to it"
8. Biography: an account of the series of events making up a person's life
the period from the present until death; "he appointed himself emperor for life"
a living person; "his heroism saved a life"
9. Living things collectively; "the oceans are teeming with life"
10. A motive for living; "pottery was his life"
11. The organic phenomenon that distinguishes living organisms from nonliving ones; "there is no life on the moon"
12. Life sentence: a prison term lasting as long as the prisoner lives; "he got life for killing the guard"
2. The course of existence of an individual; the actions and events that occur in living;
"he hoped for a new life in Australia"; "he wanted to live his own life without interference
from others"
3. The experience of being alive; the course of human events and activities; "he could no longer cope with the complexities of life"
4. Animation: the condition of living or the state of being alive; "while there's life there's hope"; "life depends on many chemical and physical processes"
5. The period during which something is functional (as between birth and death); "the battery had a short life"; "he lived a long and happy life"
6. The period between birth and the present time; "I have known him all his life"
7. Liveliness: animation and energy in action or expression; "it was a heavy play and the actors tried in vain to give life to it"
8. Biography: an account of the series of events making up a person's life
the period from the present until death; "he appointed himself emperor for life"
a living person; "his heroism saved a life"
9. Living things collectively; "the oceans are teeming with life"
10. A motive for living; "pottery was his life"
11. The organic phenomenon that distinguishes living organisms from nonliving ones; "there is no life on the moon"
12. Life sentence: a prison term lasting as long as the prisoner lives; "he got life for killing the guard"
What is Life?
What is life? Does this sound like a strange question to you? Of course we all know what is meant by the word "life", but how would you define it? Do all living things move? Do they all eat and breathe? Even though we all seem to know what is meant by saying something is "alive", it's not very easy to describe what "life" is. It's almost as hard as describing where life came from. Even the biologists (people who study life) have a tough time describing what life is! But after many years of studying living things, from the mold on your old tuna sandwich to monkeys in the rainforest, biologists have determined that all living things do share some things in common: 1) Living things need to take in energy 2) Living things get rid of waste3) Living things grow and develop4) Living things respond to their environment5) Living things reproduce and pass their traits onto their offspring6) Over time, living things evolve (change slowly) in response to their environmentTherefore, in order for something to be considered to "have life" as we know it, it must possess these characteristics.
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