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Re:Constructor Theory Solves the Riddle of Life by powera on Thursday July 16, 2015 @04:25PM (#9899691)
This article begs the question on "Biological replication and self‑reproduction are in fact such stupendously well‑orchestrated physical transformations that one must explain how they are possible under the simple, no‑design laws of physics such as ours. This additional explanation, which was not included in the theory of evolution, is essential for that theory to properly explain how living things arise without intentional design – to close the explanatory gap."

From my point of view, chemistry more or less explains how cells work, and we don't need a quasi-platonic explanation of how the universe is designed to allow for a grass-eating goat machine to explain this at all.

Re:Constructor Theory Solves the Riddle of Life by andbberger on Thursday July 16, 2015 @07:08PM (#9900415)
I couldn't agree more, this article is pseudoscience garbage.

The author appears to be one of the primary proponents of so called 'constructor theory'. I dug a bit into their research and it's setting off all of my skeptic alarms. Their primary research papers appear to be typeset in Word for christ sake.

To nitpick some particular aspects of the theory and article:

From the wikipedia article on constructor theory:

"Current theories of physics based on quantum mechanics do not adequately explain why some transformations between states of being are possible and some are not. For example a drop of dye can dissolve in water but thermodynamics shows that the reverse transformation, of the dye clumping back together, is not possible. We do not know at a quantum level why this should be so" [1]

An egregiously incorrect statement. This is basic statistical mechanics. The dye dropped into a solution diffuses and doesn't return back into the original drop is very simple: there are very few configurations of the dye/solution system where the dye is in a concentrated drop and a mind bogglingly large number of configurations where the dye is diffused throughout the solution. Nothing in physical law forbids the formation of a concentrated drop from a diffused solution - it's just ridiculously implausibly unlikely.

In fact, due to time reversal symmetry we know that the formation of the concentrated drop is explicitly allowed. Here's a little gedanken experiment: put a drop of dye in the solution and let it diffuse. After some time t, reverse all of the momenta of all of the atoms in the solution (you are God). At time 2t the dye will reform in the original concentrated droplet. But here's the zinger: keep watching and that droplet will again diffuse across the solution! Keep letting the clock run backwards and you'll probably never see the drop reform again.

One more note on that quote: the last sentence says that this is somehow forbidden by quantum mechanics. Again, this is bogus. Ensembles of large number of particles is the domain of statistical mechanics! Long discussion in of itself but the (semi)classical view is a very useful and valid perspective for many problems!

Now a comment about the article:

"Here’s where the puzzle arises. Biological replication and self‑reproduction are in fact such stupendously well‑orchestrated physical transformations that one must explain how they are possible under the simple, no‑design laws of physics such as ours. This additional explanation, which was not included in the theory of evolution, is essential for that theory to properly explain how living things arise without intentional design – to close the explanatory gap"

1. Absolute bullshit that one needs to 'justify' how certain physical states that _seem_ improbable are realized. Total garbage. Another core tenet of statistical mechanics is ergodocity [2] which states that ALL states of a system are will eventually be visited (if you have infinite time).

2. My major gripe: (non-equilibrium) statistical mechanics accounts can explain the formation of complexity (such as life)!! It is not mysterious or outside of the scope of our current framework!! By analogy consider a pot of water being heated by a hotplate from underneath: if the hot plate is on low the heat will diffuse up through the water in a disorganized manner; but, at some critical temperature convection rolls will form spontaneously in the water. They form because the increase in energy dissipation wins out over the reduction in entropy induced by their formation.

This is exactly the mechanism driving the formation of life! The existence of life is not mysterious, it's inevitable!

This article is complete and utter bullshit.

[1] https://en.wikipedia.org/wiki/Constructor_theory#Motivations

[2] https://en.wikipedia.org/wiki/Ergodic_hypothesis

Re:Constructor Theory Solves the Riddle of Life by semi-extrinsic on Thursday July 16, 2015 @07:48PM (#9900578)
> In fact, due to time reversal symmetry we know that the formation of the concentrated drop is explicitly allowed.

To take this further: you can physically do this with a similar system (replace diffusion with stirring) for very low Reynolds number flows, which are time-reversible. It's called the Taylor-Couette experiment, you can see it in action here: https://youtu.be/k7ZZtxdtmeQ

Re:Constructor Theory Solves the Riddle of Life by Confusion on Friday July 17, 2015 @02:26AM (#9901493)
I think you should realize David Deutsch is not the author of the piece and give him some more credit.

Statistical mechanics does not explain the existence of the life that currently exists. At most it proves complexity can come into existence. But not every state of the system has been visited and we don't have infinite time (and whether a billion years is sufficiently 'infinite' for some purpose first needs to be proven). The question is: is this life likely?

Re:Constructor Theory Solves the Riddle of Life by jhallenworld on Thursday July 16, 2015 @10:52PM (#9901078)
I agree with you except for the sentiment expressed by "Their primary research papers appear to be typeset in Word for christ sake."

I don't remember the name, but there was a computer architecture journal which had papers printed with dot-matrix printers (this was in the 80s). I would not discount the value of work due to this.

Re:Constructor Theory Solves the Riddle of Life by andbberger on Friday July 17, 2015 @04:45PM (#9905205)
It's a salient prior.
Re:Constructor Theory Solves the Riddle of Life by o_nate on Thursday July 16, 2015 @04:55PM (#9899836)
Explaining how a cell works is not the same as explaining how cells first came to exist. Once a cell exists, given certain conditions, it can replicate itself - we can explain each step in the process with reference to laws of chemistry. However, a different question is: How did this process get started? That's the question this article is addressing.
Re:Constructor Theory Solves the Riddle of Life by trhway on Thursday July 16, 2015 @05:32PM (#9899995)
>Explaining how a cell works is not the same as explaining how cells first came to exist

to me it became much clearer when i read somewhere (just dont' remember where) along these lines - imagine a "stick" shaped pretty simple organic molecules with one end being hydrophobic and the other hydrophilic (there are a bunch of such molecules known in organic chemistry). Having a soup of those molecules in water, some of the molecules would naturally clump together with hydrophilic ends outside and hydrophobic ends inside - kind of a small bubble. Now if on contact of a bubble with another molecule, the molecule is added into the bubble (similar like a bunch of magnets clumped together "assimilate" another magnet piece correctly orienting it), the bubble gets bigger and at some point it would naturally splits into 2 smaller bubbles (surface tension, etc...) and each bubble would continue the "assimilation"/growth and division in their turn as long as there are such molecules around... Of course it isn't even "pre-cell", it is just showing how natural physics laws can drive the initial pre-life stages.

Re:Constructor Theory Solves the Riddle of Life by Nevermark on Thursday July 16, 2015 @05:44PM (#9900058)
Another route starts with chemistry near deep sea vents where energy loaded compounds are continually spewing from hot water into cold water.

There will be a continual cascade of chemical changes at the vent, and if some random chemicals appear that increase the chances that each other are formed in that cascade, a self-reinforcing metabolic loop could occur.

The metabolic loop could optimize itself as it occasionally produced slightly more efficient self-reinforcing chemistry. Eventually this optimization might take advantage of self-organizing membranes to compress the metabolism into individual units, i.e. the first cells. At that point we would have "life".

Maybe that happened. Maybe not. But it is an alternate way for life to start in which distributed replication occurs before single replicators.

Re:Constructor Theory Solves the Riddle of Life by arjunnarayan on Thursday July 16, 2015 @07:50PM (#9900584)
> However, a different question is: How did this process get started? That's the question this article is addressing.

I consider this issue pretty much answered by Chapter 2 of the Selfish Gene, "the replicators". Link: http://www.evolbiol.ru/gene/index_2en.html#02

Re:Constructor Theory Solves the Riddle of Life by DougMerritt on Thursday July 16, 2015 @08:30PM (#9900721)
Please. I've always liked that book quite a lot, but Dawkins did not present (and did not claim to present) a theory of abiogenesis.

No one has ever presented an actual theory of abiogenesis, the current article notwithstanding, as opposed to some intriguing but speculative hypotheses that might (or might not) turn out to be part of an eventual theory (RNA world, clay catalysts, deep sea smokers, lipid membranes, etc. etc.)

Considering a totally open subject to actually be answered and finished is just saying you personally don't care to pursue the topic in more depth.

Re:Constructor Theory Solves the Riddle of Life by cristianpascu on Thursday July 16, 2015 @07:15PM (#9900445)
One thing that seems to be missed in, at least, formulating the problem of origin of life, is that cells don't reproduce themselves. No living organism reproduces itself. Cells split into two different cells and the mother cell ceaces to exist. What it's reproduced is the suite of processes that make possible the existence and multiplication of a certain kind of complex entities, what we call living organisms. It's processes themselves that pose the problem.

And thing is that laws of physics don't have it in themselves to give birth to processes when by 'process' we mean something more in line of a function, something that would not allow us to say that the Sun is a living organism, although there's processes happening inside a star.

Re:Constructor Theory Solves the Riddle of Life by euyyn on Thursday July 16, 2015 @08:24PM (#9900700)
The cell as an entity doesn't reproduce, but that's not bigger a problem than the fact that an animal as an entity doesn't reproduce either. The ideas of the extended phenotype work inward also: the genes that do reproduce are the genes that codify reproduction. All other genes and structures of the cell are merely helping that happen. They vary because that increased the long-term chances of reproduction happening.

From that point of view, there's no need to invoke processes, nor entities like organisms or cells: what's being reproduced are the genes to reproduce, and the laws governing it are just mathematics, like with a prion or a virus.