I mean is there a global and precise definition of life and what is considered living?
This is one of those question about what seems obvious but then, looking more closely, is elusive. The question What is life? was the central topic of a monograph written by Erwin Schrodinger in 1943:
E. Schrodinger, What is life? The Physical Aspect of the Living Cell. Based on lectures delivered under the auspices of the Dublin Instiitute for Advanced Studies at Trinity College, Dublin, in February 1943:
http://whatislife.stanford.edu/LoCo_files/What-is-Life.pdf
Schrodinger explains iife from the perspective of a scientist (in particular, from the perspective of a physicist and a biologist). He begins with the hereditary code script (chromosomes), starting on page 7. In this context, he considers the four-dimensional pattern of an organism: structure and functioning of the organism plus the ontogenetic development from the fertilized egg cell to the stage of maturity when an organism begins to reproduce itself. This structure is determined by only a small part of the fertilized cell, namely, its nucleus. In its cell resting state. the nucleus appears as a network of chromatin distributed over the cell. Chromosomes are distinguished by shape and size (there are two sets, one from each parent). It is these chromosomes that contain a form of code script embodying the entire pattern of an individuals's future development and its functioning its mature state.
Schrodinger goes on to discuss jump-like mutations, which he terms the working ground of natural selection, starting on p. 11. He considers the necessity of mutation a rare event, p. 14. He then puts forward laws of mutation.
First law: Mutation is a single event, p. 15.
Second law: Mutation is a localized event, starting on p. 15.
He introduces a mathematical interlude on page 18, in terms of the analysis of the sensitivity of organisms to changes in the level step or temperature.
Schrodinger observes that life seems to be orderly and lawful behaviour of matter, not based exclusively on its tendency to go over from order to disorder, but based partly on existing order that is kept up.
He asks (p. 24): What is the characteristic feature of life? When is a piece of matter said to be alive?
He answers: When a piece of matter goes on doing something, moving, exchanging material with its environment (make itself "heard"), and that for a much longer period than we would expect of an inanimate (non-living) piece of matter--to keep going under similar circumstances.
Life is truth of all events.
Life is ignoring what ordinary people say is suitable for you.
Dear Ehsan, there is no universal, precise definition of life. Neither in the scientific level nor in the personal, social or cultural dimension, as mentioned by Morteza.
In my own view, rather than this being a failure or a hurdle, it is marvelous thing to work on.
This is one of those question about what seems obvious but then, looking more closely, is elusive. The question What is life? was the central topic of a monograph written by Erwin Schrodinger in 1943:
E. Schrodinger, What is life? The Physical Aspect of the Living Cell. Based on lectures delivered under the auspices of the Dublin Instiitute for Advanced Studies at Trinity College, Dublin, in February 1943:
http://whatislife.stanford.edu/LoCo_files/What-is-Life.pdf
Schrodinger explains iife from the perspective of a scientist (in particular, from the perspective of a physicist and a biologist). He begins with the hereditary code script (chromosomes), starting on page 7. In this context, he considers the four-dimensional pattern of an organism: structure and functioning of the organism plus the ontogenetic development from the fertilized egg cell to the stage of maturity when an organism begins to reproduce itself. This structure is determined by only a small part of the fertilized cell, namely, its nucleus. In its cell resting state. the nucleus appears as a network of chromatin distributed over the cell. Chromosomes are distinguished by shape and size (there are two sets, one from each parent). It is these chromosomes that contain a form of code script embodying the entire pattern of an individuals's future development and its functioning its mature state.
Schrodinger goes on to discuss jump-like mutations, which he terms the working ground of natural selection, starting on p. 11. He considers the necessity of mutation a rare event, p. 14. He then puts forward laws of mutation.
First law: Mutation is a single event, p. 15.
Second law: Mutation is a localized event, starting on p. 15.
He introduces a mathematical interlude on page 18, in terms of the analysis of the sensitivity of organisms to changes in the level step or temperature.
Schrodinger observes that life seems to be orderly and lawful behaviour of matter, not based exclusively on its tendency to go over from order to disorder, but based partly on existing order that is kept up.
He asks (p. 24): What is the characteristic feature of life? When is a piece of matter said to be alive?
He answers: When a piece of matter goes on doing something, moving, exchanging material with its environment (make itself "heard"), and that for a much longer period than we would expect of an inanimate (non-living) piece of matter--to keep going under similar circumstances.
interesting question. another complementary question to this thread might be "what is a global definition of being awake/ or conscious?" as there might be slightly different degrees and definitions of being awake/conscious.. good luck finding the answer and let us know! thanks.
Hello Ehsan,
I guess when it comes to the definition of life we have to face the same trouble we have when it comes to other terms: Your definition is hardly dependend on the field of research.
If you are asking for a global definition which is sufficient as a starting point and with which many fields agree I would suggest this one:
Life is a state/condition lifeforms share
- Systems marked off from their environment
- Interaction with the environment
- Self-organisation and self-regulation
- Reproductive
As you can see the 'global definition' is very basicly and causes more questions than answers.
As far as I remember anything which falls under the aspect of life has at least to fullfill three of those criteria (but I might be wrong and in this case please correct me).
I will give you an example why the first criteria does not always work: Some bacterias produce substances through which they create their environment they can live in. So are they 'marked off' from their environment then? Or is it interaction? Where exactly are the physical borders? This might be naive at first glance. However: You might find a similar problem when it comes to extensions and enhancements. Where does a person start? Where does the person end? (Also take a look at transhumanism, extended mind theories and so on).
James also brought in a few really good ideas which especially explain the historical aspects which are at least necessary to answer questions like 'What is organisation?'.
I would also recommend you to deal with the topic of non-mathematical function (f.e. the paper of Wright; I will provide you a link at the end of this post) and minimal systems. This might give you a few good insights too.
http://mechanism.ucsd.edu/teaching/philbio/readings/wright.functions.%201973.pdf
Schrodinger wrote that wonderful book about 10 years before the discovery of the double helix. Watson and Crick answered your question almost completely, at least in the biological sense.
The condition that distinguishes animals and plants from inorganic matter, including the capacity for growth, reproduction, functional activity, and continual change preceding death.
Life is a space-time phenomena that every living matter possesses naturally from its conception and physical beginning to its death .
On the other hand living is a continuous existence of a matter with life through either instinctive ways at the comfort of the host and mercy of the environment (non thinking creatures from microscopic organisms to giant animals) or through thoughtful, purpose driven, highly self conscious mind to study, design and create means to control and utilize the environment for better and longer.
There is no and should not be a global definition of what life for instinctive creatures as they survive solely based on the type of the host and terrain of the environment they live in.
But for humans, the global society is creating a kind of living standard any person should have - a global definition of what good life for a human being is. In this regard United Nation's annual report of human development index or prosperity index, wealth disparity index, etc, are ways of globalizing the term good living.
As you can see, there seems not to be a precise and global definition for the life except limiting your question to a specified field of science.
Gilbert Levin who was behind some of the experiments of the 1976 viking package designed to detect life on Mars, claims that the LR-equipment did detect life on Mars. I must confess - being a bit of a "contrarian" - that I'm not far from agreeing with him what few would dare say !. I'm only puzzled by the need for microorganisms to be somehow deeper under the surface than what was scratched by the Viking lander to survive to the lethal radiations received (1/100th of terrestrial of atmosphere and absence of protecting magnetic field). But reading his papers will teach a lot on what one can think life is and how to detect it !
http://www.gillevin.com/mars.htm
http://en.wikipedia.org/wiki/Gilbert_Levin
Well Ehsan, you are from the technical field. And I guess you are asking for a special porpuse. At least all technicians and computer scientists are interested in recreating life. However it must be made clear: Other 'specified fields' are not like they can create their own circumstances but they are dependend from what they research. I am not saying that f.e. computer scientists can create anything they want. But there is at least far more creativity. So it's a bit unfair to say that those answers are 'limited'. Of course they are limited. But for sure not by people themselfes because of a lack of creativity and spirituality but because the nature of this planet itself is limited. We have a special form of life which has developed. And beside that most of us don't know much about other forms. We are not even speculating. For that you need to ask exo-scientists if you want to know more about possibilities. Those definition about life don't deal with what is possible but rather with what seems to be necessary. What we all (no matter how different in form) do share. And we normaly automatically recognize: Well... this is life. So... some people obviously have trouble with that. For example there are people who think it is a quite good idea to have dolls, walls or shoes as 'partners'. Maybe telling themself: "You know what... that shoe is sufficient."... and than it is sufficient. I am not trying to compromise any work of anyone here: But for some reason for most of us reasonable beings there are limits (especially when it comes to reproduction). And here we are fair enough to say: We cannot intercourse with a guinea pig but they are sharing something specific with us. And to hit another border from a different perspective: Let's say we knew about afterlife. Would we call that life anymore? I guess you all agree we would not. We would rather call it spirit or ghost or soul or whatever. Obviously 'soul' itself is not sufficient for life. Also I sympathize with many answers here which swipe these more methaphysical thoughts: Is that really life? Or are those aspects of something else? (f.e. degree of consciousness). I cannot tell you if there is consciousness without organism. But we wouldn't define it as life anymore.
Life is the quality which distingueshes inanimate matter from organisms that can grow, eat, move, reproduce and respond to stimuli. The state is limited by birth and death.
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