On 19-01-2021 08:38, 'Brent Meeker' via Everything List wrote:
On 1/18/2021 11:27 PM, smitra wrote:
On 19-01-2021 05:44, 'Brent Meeker' via Everything List wrote:
On 1/18/2021 3:58 PM, smitra wrote:
On 18-01-2021 18:03, Evgenii Rudnyi wrote:
Am 18.01.2021 um 01:01 schrieb Lawrence Crowell:
There are molecules that already do this. DNA and polypeptides are
sequences that are in effect codes.
Yes, this is exactly the point by the prize. The question is to
show
how something like this could happen spontaneously.
Evgeny
It requires violating local thermodynamic equilibrium. I'm working
on an article and a few presentations for upcoming conferences where
I explain this in detail. This then proves that none of the current
models for prebiotic chemistry can explain the origin of life.
There are not models that assume thermodynamic equilibrium.
Biologists
aren't stupid. They all know that abiogenesis requires a source of
energy as low entropy. Urey showed that lightning can create organic
molecules. Nick Lane has a theory based on alkaline vents on the
ocean floor. He bases this on the ubiquity of ADP->ATP as the energy
carrier for all living organisms. These vents form complex mineral
structures which provide the kind of micro-environments you mention.
Brent
Of course they don't assume thermodynamic equilibrium, but they do all
assume local thermodynamic equilibrium (LTE). Out of equilibrium means
that the system is not described by a single temperature and a single
set of chemical potentials, there are instead temperature gradients
and chemical potential gradients. Locally in a small enough volumes,
you do have approximate thermal equilibrium, the departure from
Maxwell-Boltzmann distribution will be very small locally (the
deviation is not exactly zero otherwise you could not have heat
conduction and diffusion).
And those deviations are the whole point of driving the entropy
decreasing processes of life.
In contrast, a violation of LTE means that LTE breaks down completely.
I.e. you cannot describe the thermodynamic state of the system using
chemical potentials and a temperature that depend on position and
time. The deviation of the distribution function of molecules from
Maxwell-Boltzmann form is then very large.
Which I might expect where molten lave meets cold sea water.
A violation of LTE is impossible under Earth-like conditions.
Apparently, even in the interior of stars, LTE is still an extremely
good approximation, according to my astronomy professor who lectured
about stellar physics. Thing is that under LTE you cannot get to the
sort of micro-environments with random structures on the molecular
scale that are required for the origin of life.
So you're telling me that photon absorbtion in photosynthesis is LTE.
That those sparks in Urey's experiment were in LTE?
In these processes where LTA is briefly violated the molecules will soon
find themselves elsewhere where LTE is again valid. In general, you
can't build something on the molecular scale at some point without
molecules farther away interfering with what is going on (unless you
have sophisticated machinery already present to exploit the process,
like in case of photosynthesis). So, a process that initially breaks
chiral symmetry in one way will soon undergo interactions with other
nearby molecules that will cause the process to go in the other
direction. On the long term such effects will then get averaged out.
The fundamental problem you then have is that with only simple molecules
you are subject to the Eigen limit. All you can do is to get to polymers
that can contain information that can copy themselves using template
copying. But the error rate per copied part then defines the maximum
amount of information that can be contained, for realistic systems this
is way too small to code for a sophisticated error correction system.
Without such systems the error rate will thus remain high and you can
never get to the biological world.
If instead you already have forged very large molecules in
micro-environments (that are themselves also made out of organics), you
can circumvent the Eigen limit due to the size of the molecules.
Information can also be present in the larger scale properties of
molecules that can be copied far more accurately. This possibility is
not directly available in conventional prebiotic models, because of the
small size of the molecules one starts out with. They have to resort to
very complex models involving such things as autocatalytic sets to evade
this problem but that brings in a whole host of other problems.
Saibal
Brent
Saibal
A viable scenario is to get to a large random organic structure
forged in an interstellar ice grain, where organic molecules at low
temperatures under UV irradiation will only interact with nearest
neighbors. Thermodynamic equilibrium is never reached, the system
moves farther and farther away from this as the reactions under UV
radiation continue. This way one gets to large so-called percolation
clusters of organic molecules that have a random structure.
Such random organic structures look totally useless to explain the
origin of life, because what you want are the very specific
molecules that are involved in the biochemical processes in living
organisms. However, the structure of these random organic molecules
is such that it has interior structures with compartments containing
large random polymers and random interior surface structures. These
can then serve as micro-environments within which prebiotic
chemistry under normal local thermodynamic equilibrium conditions
can work. With a finite number of N structures in a compartment one
will break symmetries such as chiral symmetry at a level of
1/sqrt(N). Small molecules can escape the compartments via pores in
the random structure while large molecules get trapped inside.
Saibal
LC
On Monday, January 4, 2021 at 12:28:18 PM UTC-6 use...@rudnyi.ru
wrote:
"How do you get from chemicals to code? How do you get a code
without
designing one?"
"What You Must Do to Win The Prize
You must arrange for a digital communication system to emerge or
self-evolve without "cheating." The diagram below describes the
system.
Without explicitly designing the system, your experiment must
generate
an encoder that sends digital code to a decoder. Your system
needs to
transmit at least five bits of information. (In other words it
has to be
able to represent 32 states. The genetic code supports 64.) "
https://www.herox.com/evolution2.0
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