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Tue Jan 8, 2019, 04:31 AM

Our current best guess how life comes from non-life.

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2015GC005783

https://books.google.de/books?id=h0L2BwAAQBAJ&pg=PA15&lpg=PA15&dq=shockwave+synthesis+life&source=bl&ots=sc9DBk_m-4&sig=TfiwKU1hOvkMcwzbrG2APaQz8Og&hl=en&sa=X&ved=2ahUKEwjV5v7I7N3fAhWPx4UKHZtyB-oQ6AEwFXoECAkQAQ#v=onepage&q=shockwave%20synthesis%20life&f=false

Shockwave synthesis.

The problem is that life is a state of matter with less entropy than non-life. But entropy increases over time. So how do we get to a state with less entropy?

What most people don't know: The laws of thermodynamics are only valid in a thermodynamic equilibrium. Systems out of equilibrium move towards that equilibrium with a certain speed. But if you change things so fast that the system cannot go to equilibrium, it's possible to break the laws of thermodynamics.

During shockwave-synthesis you have soundwaves travelling through e.g. a chemical solution. If the frequency is high enough (e.g. from a really short, really strong event, e.g. an impact), molecules can do chemical reactions while not being in thermodynamic equilibrium with the rest of the liquid.

With this, it's possible for simple molecules to react to complicated molecules.

A current theory is that a meteorite impacted on Earth and that this impact synthesized the first building-blocks of life.





If these complicated molecules happen to find other complicated molecules that in combination enable chemical processes that keep these molecules intact and even enable the synthesis of more identical molecules, then you have life.

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Response to DetlefK (Original post)

Tue Jan 8, 2019, 05:20 AM

1. I'm not sure I believe Life has less entropy than non-life

I mean, does a mouse have less entropy than a perfectly regular crystal of salt?

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Response to Loki Liesmith (Reply #1)

Tue Jan 8, 2019, 07:14 AM

3. Entropy is the question how many ways there are to create a certain situation.

In a crystal it's easy to switch two atoms without changing the crystal as a whole. An organic compound has many different kinds of atoms and there are far less options for switching two random atoms without changing the system.

That's why a crystal has a high entropy and life has a low entropy.

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Response to DetlefK (Reply #3)

Tue Jan 8, 2019, 09:43 AM

5. Respectfully I think that's exactly backwards

A crystal should ideally have very low entropy. Ice has a lower entropy than liquid water and much lower than, say water vapor.

Furthermore if, per Shannon, information is entropy, then a mouse should have much higher entropy than a crystal as it takes many more variables to describe the mouse than the crystal.

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Response to Loki Liesmith (Reply #5)

Tue Jan 8, 2019, 09:55 AM

7. To elaborate a bit more

Life should occupy a middle regime between highly ordered activity and random fluctuation. It should be at a point somewhere between high entropy and low entropy. Perhaps even a critical point or a phase transition between the two regimes.

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Response to Loki Liesmith (Reply #5)

Tue Jan 8, 2019, 09:58 AM

8. Yes... ice has less entropy than water or vapor.

Because liquid water and vater have more options how to create a certain situation. Ice can only exist if the molecules are at certain positions. Liquid water and vapor remain liquid water and vapor if the molecules are out of place.

Again: The margin of error is very small for a living being. There are only very few ways how you can switch out atoms or move them around without ruining everything.

Complicated systems have a low entropy, simple systems have a high entropy. Entropy is a measure for the LACK of information, not for information itself.

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Response to DetlefK (Reply #8)

Wed Jan 9, 2019, 12:50 AM

9. You have it backwards.

Entropy is determined by how much information you need to fully describe the system. Very ordered systems require very little information to describe them. If you want to describe every atom in a crystal, all you need to do is describe where one atom is, and the structure and orientation of the crystal, and then you can figure out where every other atom is. If you want to describe where every atom in a living being, that takes a LOT of information.

Once common misconception that I see (I teach physics...) often in students is that when people describe entropy as disorder vs. order, they don't mean that it's randomness vs intricacy, what it means is that things that have regular patterns in them are low entropy and things with irregular arrangements have higher levels of entropy.

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Response to Salviati (Reply #9)

Wed Jan 9, 2019, 10:28 AM

10. Wikipedia.

Entropy is related to the number of ways a certain situation can be realized. The more microscopic ways there are to create the same macroscopic situation, the higher the entropy of this macroscopic situation.
https://en.wikipedia.org/wiki/Entropy

I believe, you forget that though atoms are not unique, they are treated as unique individuals in this context.

Let's say, we have a crystal consisting of 4 metal-atoms. There are 4!=24 ways to build that crystal. If we have a crystal of 2 Na and 2 Cl-atoms, there are 2!*2!=4 ways to build that crystal.

Let's say we compare an ice-crystal and a water-droplet. The ice-crystal is an ice-crystal only if the water-molecules are at the right locations. The water-droplet is still a water-droplet if the water-molecules are slgihtly out of position.
=>
There are more ways to make a water-droplet than to make an ice-crystal.
=>
Liquid water has more entropy than ice.

Let's say we have a non-living matter and living matter. The non-living matter stays non-living matter if a few atoms are slightly out of place. The living matter dies if too many atoms are out of place.
=>
There are less ways to make living matter than there are to make non-living matter.
=>
Living matter has less entropy than non-living matter.

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Response to DetlefK (Original post)

Tue Jan 8, 2019, 06:35 AM

2. I heard a geologist say if you have two rocks that collide you can have life.

It was a show on PBS about evolutionary biology. He gave examples. I'm going with that idea. Sounds implausible but he has me believing.

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Response to DetlefK (Original post)

Tue Jan 8, 2019, 08:48 AM

4. May The Force be with you!

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Response to DetlefK (Original post)

Tue Jan 8, 2019, 09:53 AM

6. **SIGH** Entropy must increase or stay constant WITHIN A CLOSED SYSTEM. (badly mistitled OP)

This is a FAR more important qualification than any requirement for equilibrium -- in fact the equilibrium argument is superfluous. Complex life evolved freely -- wantonly -- on Earth because Earth is anything BUT a closed system. The Sun constantly beams down a torrent of energy onto the Earth's surface. Virtually all of this radiation is eventually re-radiated back into space, where it expands virtually unimpeded into an effectively infinite volume, creating all the entropy that could ever be required, and allowing the local decrease in entropy that is absolutely characteristic of every living organism. In the process of being absorbed, flowing from one point to another, and eventually being lost again, that energy does useful work on the Earth's surface, including creating energetic molecules which plants and animals alike rely on for survival. That accumulation of 'negentropy' is perfectly allowed by the laws of thermodynamics in an open system. If we were to regard the Sun, the Earth, AND all the radiation emitted by the Sun as a closed system (it isn't perfectly, but close enough) then entropy is increasing massively overall, and the fact that a little turbulence in the flow of energy has produced all the complexity of life on earth is not even a jot in the entropy balance.

The suggestion that an impact is involved is also completely unnecessary. We have known since the days of the Miller-Urey experiment that radiation alone is sufficient. All the faddish theories about "life formed in outer space" will eventually be discarded as being as untenable as they are unnecessary. The attraction of these theories is romantic, not scientific -- there are no holes in any theories demanding an extraterrestial origin of life.

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Response to eppur_se_muova (Reply #6)

Wed Jan 9, 2019, 03:12 PM

11. Plus heat flow, and chemical energy, from thermal vents powered by the Earth's internal heat

(and radioactivity, which I believe is credited with keeping the centre of the Earth hot a lot longer than it otherwise would have remained), which may be a better candidate than radiation, since the capture of electromagnetic energy is a relatively advanced feature of life.

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Response to muriel_volestrangler (Reply #11)

Thu Jan 10, 2019, 08:47 AM

12. Correct, I should have said heat and radiation *on a planetary surface/ocean* is the best candidate.

And of course, Urey's experiment added electric discharges (lightning) as well.

Darwin's "warm little pond" still makes infinitely more sense than expecting molecules to find each other in near-vacuum, where the concentrations may be smaller by factors exceeding 10^20.

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