What is needed for life?

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Our definition of life keeps changing as we discover living things in places we did not think life could exist. My question is how would we define life if this trend continues? As of now we believe all living things need liquid water. But we may find organism living in any kind of liquid. But is a liquid even necessary? Is solid material needed for life to anchor on? I am thinking of life in the most optimistic way and wondering how to define it. Could in theory life take hold anywhere there is a slow exchange of energy over a long period of time?
 

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  • #2
Ryan_m_b
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Our definition of life doesn't really change when we find organisms living in places we didn't think they could, on the contrary we recognise them because of our definitions. As we understand it water is necessary for life but there has been speculative work on using other liquids as a solvent. I doubt any non liquid media could give rise to life.

There is no strict definition of life and there is constant debate regarding things like viruses and if they should count as alive. The broad consensus is listed here:
http://en.wikipedia.org/wiki/Life#Definitions
 
  • #3
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So a liquid environment which has a lot of activity (but not to much) and a good variety of elements and giving enough time may be all that is needed?
 
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Thanks for the link :) It seems life has a lot of limitations chemically. But putting the chemical soup aside for a second what else is a necessity? Life needs energy and it gets this energy from low entropy systems and contributes to the over all increase of entropy. So is the right chemical soup, a low entropy environment, and time may be all that is needed?
 
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Ryan_m_b
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You'd need the right energy input at the right time with the right composition of elements, but we don't know for sure. Experiments like the Miller-Urey experiment showed that you could get certain biomolecules to form under "primordial" conditions. However there are theories that geology matters as well, IIRC there is speculation that pores in rocks aided in the formation of the first cellular structures.
 
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Thank you. That article seems to be exactly what I am looking for.
 
  • #9
Pythagorean
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No problem. Keep in mind that while many people appreciate England's approach, it's still speculative. But imo, it's worth testing experimentally.
 
  • #10
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If his approach is not right I bet it is pretty close. Much how we use to think we were at the center of the universe, we also think life is something special. But we will eventually find out that it is just a natural process of entropy. Kinda of depressing.
 
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How would this be tested. I did not find anything about that?
 
  • #12
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How would this be tested. I did not find anything about that?

Prentiss, who runs an experimental biophysics lab at Harvard, says England’s theory could be tested by comparing cells with different mutations and looking for a correlation between the amount of energy the cells dissipate and their replication rates. “One has to be careful because any mutation might do many things,” she said. “But if one kept doing many of these experiments on different systems and if [dissipation and replication success] are indeed correlated, that would suggest this is the correct organizing principle.”
 
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"... that would suggest this is the correct organizing principle.” Perhaps this would be better read as "...that would suggest this is the correct an organizing principle.”
 

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