Hi Richard Ruquist 

Does "life thrive in a prebiotic soup" ? Then he's done.

But he doesn't really say how he starts-- if with bacteria
he cheats, because they are already alive.

Roger Clough, rclo...@verizon.net
9/11/2012 
Leibniz would say, "If there's no God, we'd have to invent him 
so that everything could function."
----- Receiving the following content ----- 
From: Richard Ruquist 
Receiver: 4dworldx,Swines,MindBrain,everything-list,evolutionary-psychology 
Time: 2012-09-10, 11:16:03
Subject: Physicist Derives Laws of Thermodynamics For Life Itself


FYI

---------- Forwarded message ----------
From: richard ruquist <yann...@yahoo.com>
Date: Mon, Sep 10, 2012 at 11:10 AM
Subject: Fw: the physics arXiv blog
To: "yann...@gmail.com" <yann...@gmail.com>





----- Forwarded Message -----
From: Technology Review Feed - arXiv blog <ho...@arxivblog.com>
To: yann...@yahoo.com 
Sent: Monday, September 10, 2012 8:18 AM
Subject: the physics arXiv blog



the physics arXiv blog 
 


Physicist Derives Laws of Thermodynamics For Life Itself 
Posted: 10 Sep 2012 03:58 AM PDT
The laws of thermodynamics must apply to self-replicating systems. Now one 
physicist has worked out how

Here's an interesting thought experiment. Imagine a box filled with a variety 
of atoms and molecules in proportions roughly equivalent to the composition of 
the prebiotic soup in which life thrives.?
How likely is it that these molecules will arrange themselves into 
fully-fledged living thing, a bacterium, for example? That's a tough question 
but Jeremy England at the Massachusetts Institute of Technology in Cambridge 
has worked out how to calculate an answer, at least in theory. His results make 
for fascinating reading.
Part of the problem here is that life itself is hard to define. But England has 
a way round this. His idea is to examine every combination of states that are 
possible in this box and to consult an omniscient microbiologist about whether 
each state represents a bacterium or not. In that way, it ought to be possible, 
at least in principle, to gain an idea of the statistical physics involved.
Next, he asks the microbiologist to take another look at the box after a period 
that is roughly equivalent to the time it takes for bacteria to divide.
The question then is how likely is it that there will be two bacteria in the 
box. ?
Once again, the omniscient microbiologist could look at every possible state of 
the box and say whether or not self replication has taken place. If the box 
contains two bacterium, it's possible to work how much entropy has been created 
in the process and how much heat used.?
England throws in some basic laws of thermodynamics and in this way builds a 
statistical physics model of self replication, a model that is analogous to the 
laws that govern the statistical behaviour of any set of particles in a box.
By way of comparison, he also looks at the statistics that govern the reverse 
process--the spontaneous decomposition of the bacteria into carbon dioxide, 
hydrogen and so on.
This sets an important bound on what is thermodynamically possible in this 
system: in effect, England derives the second law of thermodynamics for the 
system. From this he works out various 'laws' such as the minimum amount of 
heat that a single round of cell division ought to produce.?
Finally, he puts some numbers into his model, including figures such as the 
life time of peptide bonds in biological systems, to find out how much heat 
complex systems like E. coli bacteria ought to produce when they replicate.
It turns out that E. coli bacteria are remarkably efficient replicators. "The 
organism can convert chemical energy into a new copy of itself so efficiently 
that if it were to produce even half as much heat it would be pushing the 
limits of what is thermodynamically possible!" he says.
He does a similar calculation for the replication of RNA and DNA molecules. 
This suggests that in terms of thermodynamics, replication is ?uch easier for 
RNA than DNA.?
That's an interesting result given that many biologists have suggested that the 
first self-replicating systems in Earth's pre-biotic soup must have been based 
on RNA rather than DNA
In the past, biologists have studied the catalytic properties of RNA that are 
crucial for living cells and noted that DNA does not share these properties. So 
the thinking is that RNA must have come first in the replicating timeline, with 
DNA evolving later as life became more complex . ?
England's work backs up this idea but for completely different reasons--RNA is 
thermodynamically better at self replication. A fascinating result.
The work has an important limitation, however. It fails to tackle the 
definition of nature of life and instead defers the problem to an omniscient 
microbiologist who, it is assumed, can always provide an answer.?
There is a tantalising hint that England's approach could one day solve this 
problem. By exploring the role of statistical physics in more detail, it maybe 
possible to define life in terms of precise thermodynamic limits.
Which is why it'll be worth watching where England takes his idea next.
Ref: arxiv.org/abs/1209.1179: Statistical Physics of Self-Replication?


  


       
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