Tried reading the paper [1]. I understand the authors are academics, which is why I'm surprised the paper reads like a layman's attempt at a contributing to a "theory of everything", or at best, an inquiry written by a 18th century European philosopher of science.

- "identification of conceptual equivalencies among disparate phenomena were foundational to developing previous laws of nature" - what exactly is a "conceptual equivalence"? You mean models? Unifying disparate observations into models is basic science. Not sure why it is highlighted here as some important insight.

- "The laws of classical physics emerged as efforts to provide comprehensive, predictive explanations of phenomena in the macroscopic world" - followed by a laymen's listing of physical laws, then goes on to claim "conspicuously absent is a law of increasing “complexity.”"

- then a jumble of examples including gravitation, stellar evolution, mineral evolution and biological evolution

- this just feels like a slight generalization of evolution: "Systems of many interacting agents display an increase in diversity, distribution, and/or patterned behavior when numerous configurations of the system are subject to selective pressure."

At this point, I gave up.

[1] https://www.pnas.org/doi/10.1073/pnas.2310223120

"Complexity" is a hugely problematic term when used in this way - remember that entropy and complexity are related, but they are not interchangeable. A complex system can have lower entropy than a simpler system, and conversely, a system can have high entropy but be relatively simple. By mingling these terms without specifying objective reference points, it all just comes out as word salad.

This paper just reads like an attempt at sounding smart while actually saying little.

Coincidentally, I'm reading Walker's book "Life as No One Knows It: The Physics of Life's Emergence" on the same topic. (Walker is one of the researchers in the article.) Summary: I don't like the book. The book was motivating me to write an article "Books I don't like", but I'll comment here instead :-)

The book describes "Assembly Theory", a theory of how life can arise in the universe. The idea is that you can quantitatively measure the complexity of objects (especially chemicals) by the number of recursive steps to create them. (The molecule ATP is 21 for instance.) You need life to create anything over 15; the idea of life is it contains information that can create structures more complex than what can be created randomly. The important thing about life is that it isn't spontaneous, but forms an unbroken chain through time. Explaining how it started may require new physics.

If the above seems unclear, it's because it is unclear to me. The book doesn't do a good job of explaining things. It looks like a mass-market science book, but I found it very confusing. For instance, it's unclear where the number 21 for ATP comes from, although there's an analogy to LEGO. The book doesn't define things and goes into many, many tangents. The author is very, very enthusiastic about the ideas but reading the book is like looking at ideas through a cloud of vagueness.

The writing is also extremely quirky. Everyone is on a first-name basis, from Albert (Einstein) to Johnny (von Neumann) and Erwin (Schrödinger). One chapter is written in the second person, and "you" turn out to be "Albert." The book pushes the idea that physics is great and can solve everything, covering physics "greatest hits" from relativity and quantum mechanics to gravitational waves and the Higgs boson. (The underlying theme is: "Physics is great. This book is physics. Therefore, this book is great.") The book has a lot of discussion of how it is a new paradigm, Kuhn's paradigm shifts, how it will move astrobiology beyond the pre-paradigmatic phase and unify fields of research and so forth. It's not a crackpot book, but there are an uncomfortable number of crackpot red flags.

I'm not rejecting the idea of assembly theory. To be honest, after reading the book, I don't understand it well enough to say which parts seem good and which parts seem flawed. There seem to be interesting ideas struggling to get out but I'm not getting them. (I don't like to be negative about books, but there are a few that I regret reading and feel that I should warn people.)

Douglas Adams was right all along then.

"There is a theory which states that if ever anyone discovers exactly what the Universe is for and why it is here, it will instantly disappear and be replaced by something even more bizarre and inexplicable. There is another theory which states that this has already happened."

Amateur speculation, but informed by professionals: I think this tendency toward complexity is situational, not fundamental. Specifically, it's a product of this stage of the universe having lots of available energy. More complex structures are favored when/because they can consume more energy and increase entropy more effectively. The complexity will probably start fading when the hydrogen-fusion party dies. The second law will continue on its way.

I'm fairly sure this is already in the usual canon of statistical mechanics.

"When one compares a hotplate with and without a Benard cell apparatus on top, there is an overall increase in entropy as energy passes through the system as required by the second law, because the increase in entropy in the environment (at the heat sink) is greater than the decreases in entropy that come about by maintaining gradients within the Benard cell system."

This reminds me of Teilhard de Chardin's take on complexification, as laid out in his seminal book Le Phénomène humain. See e.g., this article[0] for a simple overview of the hypothesis. For further reading, I recommend the excellent new translation by Sarah Appleton-Weber, The Human Phenomenon[1].

[0] <https://onlinelibrary.wiley.com/doi/pdf/10.1002/%28SICI%2910...>

[1] <https://www.liverpooluniversitypress.co.uk/doi/book/10.3828/...>

I never trust the sense of new scientific ideas I get from popular press articles. But this comes across as highly questionable, “Intelligent Design” redux stuff. Sure there are some interesting points about information theory etc, but overall it sounds like a lot of scientists desperately cribbing concepts they don’t actually understand from other fields and misapplying them to oversimplified computer simulations someone who barely understands Python wrote 20 years ago, and assuming the simulation, which has built-in, accidentally hard-coded selection factors, is the same as reality.

Seriously, phrases like “selection for function”, unified theories of biology and physics, and big ideas about the second law of thermodynamics are major red flags.

Sentences like this, i.e. "everything turns more complex", must be formulated much more precisely in order to become true.

The article talks a lot about biological evolution, but in that case the only claim that is likely to be true is that the complexity of the entire biosphere increases continuously, unless a catastrophe resets the biosphere to a lower complexity.

If you look only at a small part of the biosphere, like one species of living beings, it is extremely frequent to see that it evolves to become simpler, not more complex, because a simpler structure is usually optimal for constant environmental conditions, the more complex structures are mainly beneficial for avoiding extinction when the environmental conditions change.

“The law that entropy always increases holds, I think, the supreme position among the laws of Nature. If someone points out to you that your pet theory of the universe is in disagreement with Maxwell's equations - then so much the worse for Maxwell's equations. If it is found to be contradicted by observation - well, these experimentalists do bungle things sometimes. But if your theory is found to be against the Second Law of Thermodynamics I can give you no hope; there is nothing for it to collapse in deepest humiliation.” ― Arthur Eddington, New Pathways in Science

I remember reading somewhere that maybe the purpose of life is to increase entropy in the universe. If that is true and we haven't found any sound evidence of life elsewhere, I don't know.

The law of increasing complexity holds at least for the software that I write, so yeah—plausible...

This seems to be in a similar vein to constructor theory / assembly theory:

https://en.wikipedia.org/wiki/Constructor_theory

https://en.wikipedia.org/wiki/Assembly_theory

The thing that is often missed in debates about entropy and Universe is that the classical notion on entropy is not compatible with General Relativity. Richard Tolman almost 100 years ago proposed an extension that was compatible.

One of the consequences of that extension was a possibility of a cyclic universe. On expansion one sees that classically defined entropy increases but then it will decrease on contraction.

These days that work is pretty much forgotten, but still it showed that with GR heat dearth of the universe was not the only option.

Isn't that like saying that "some things take time"? Complexity also takes time to develop through a myriad probabilities. We even define complexity along the concept of things taking time or equivalent space/memory. As the authors say, functional information of physical systems is very difficult to quantify. Until then, this is another formulation of the anthropic principle , but with complexity instead of humanity.

Pretty cool. I often wondered if the universe was evolving similar to natural selection via a reinforcement learning process. Wave function collapses to the value that maximizes some objective function.

How would you test for it though? I've seen enough residual data from RL processes to almost see semblences of patterns that could be extracted and re-applied at a macro scale.

Likely could be due to laws of math in this universe where more is always desired more then less.

This theory is absurd. They're unjustifiably generalizing from a single system--biological evolution on Earth[1]. There are literally no other places in our solar system even that are rapidly evolving to more complexity. Lots of dead rocks, hot and cold, and a bunch of boiling gas balls. Incidentally, none of these are turning into Cybertron. As it turns out, the chemistry that we know to be necessary for self-replicating things just doesn't work there. (Maybe there are other chemistries that will work, we don't know). So this specific chemistry and this specific set of conditions to kick off and indeed allow self-replication to continue are pretty damn important to understanding how it works.

A "new force of nature"? It's just so pretentious. Some interesting biases of a selection process driven by copious excess energy doesn't make for a new force of nature. Otherwise we'd be positing all kinds of absurdities that are not directly explained by particle physics are woo woo a new force of nature--fashion choices (hey, copy, select, mutate there too).

[1] And no, I don't think that the computer simulations of evolution they carry out are any additional evidence. So you made a computer program with a copy/select/mutate loop in it. Big deal. I can make a computer simulation about anything.

so at heat death of the universe, things will be more complex? i think not. There is clearly a limit to complexity, where that is when that is we don't know.

How does one measure complexity 'in the universe'?

It is following the Fundamental theorem of software engineering, another level of indirection.

"In this new view, biological evolution appears not as a unique process that gave rise to a qualitatively distinct form of matter — living organisms. Instead, evolution is a special (and perhaps inevitable) case of a more general principle that governs the universe. According to this principle, entities are selected because they are richer in a kind of information that enables them to perform some kind of function."

Sounds like they're struggling to accept that the cosmos is not conscious and it doesn't design, and possibly confuse the fantasies we construct to, as it might be phenomenologically put, make sense of our environment, with the environment itself.

In ancient abrahamic cosmology it was proposed that the cosmos was designed, and first it was stone and water and so on, and then the biological matter was put in there, segmenting stone, hippopotamus and human into a kind of cosmological hierarchy of ethical and divine importance. Famous ancient greek philosophers imagined that there was another world shaping ours, geometrically purer and to people with a particular taste perceived as obviously more beautiful and holy.

Different strains of similar thinking survived in parts of the world for a long time, and had a renaissance due to european colonialism spreading it with a diverse set of tools.

One of the strongest views that followed is a cosmological dualism, the belief that there is something like soul or mind that is different from matter, usually paired with the belief that this is how truth enters the world and that truth is otherworldly, etherical.

Modern physics turned out to be absolutely brutal towards ideas like these. For a hundred years experiment upon experiment just smashed such segmentations and expectations against a growing mountain of experiential evidence. As of yet we have no evidence of the cosmos being governed by laws and selection, it just is what it is and the supposed laws are human interpretations, hopes and fantasies.

Protestant christianity is in an especially bad place due to this development, since it bets all it has on mental phenomena being more real than matter. Catholics and muslims can fall back on arguing that the divine is unknowable and that the effects of certain acts and traditions are socially beneficial, which sometimes puts them at odds with or makes them absolutely incompatible with worldly regimes of power. Protestant ideology on the other hand, can be fitted in with basically any regime, material conditions just aren't that important, ethically or otherwise.

Looking at the micro-perspectives we didn't find geometrical simplicity, instead we found weird, messy fields and almost-existences, putting all sorts of expectations about the foundations of the cosmos into question. Maybe it'll change, but at the moment there's no evidence for some grand principle or cosmic selector or whatever. One might argue something here about cosmic constants or the symmetry Dirac sussed out but that's still just pushing human experience into an algebra.

The expectation that life is somehow special is wrong. There is, as far as we can see, no difference in the quarks in a dog and those in a rock. The argument that 'DNA encodes more information' is childish, there are repetitive structures everywhere, like in the crystalline structures in a piece of rock. Protein sacks carrying their own emulation of a particular old ocean on a particular planet and flubbing around on land, carefully putting in salts and carbon and so on to keep it going, is neither more or less complex, neither more or less "information dense" in itself, than a photovoltaic panel pushing electrons to light up a screen.

There is a good book from the nineties on this topic, https://en.wikipedia.org/wiki/Ilya_Prigogine#The_End_of_Cert.... One should be very suspicious of people that talk about being cosmically selected, or about natural laws.

> a system can have high entropy but be relatively simple.

Good examples of these are anything that Kolmogorov-compresses well. For example, by almost any measure the output of a pseudo random number generator has high entropy. Yet it has low information density (low complexity), as the program that generates the sequence, plus its state, is really small.

Yes indeed. As I understand it, entropy is about states that are more likely.

I wonder if it always increases though? Eventually there will be enough entropy that any change may cause it to reduce or oscillate? (At universe / reachable universe scale).

that is why the complex is distinct from the complicated

Walker gave a talk recently at Long Now on Assembly Theory that sounds like it did a better job of getting the point across:

https://longnow.org/ideas/informational-theory-life/

I felt similar reading that book. She seems very clear that she wants to develop paradigmatic physics, and wants Assembly Theory to be paradigmatic, but there's not a lot of meat on the bone.

> It's not a crackpot book, but there are an uncomfortable number of crackpot red flags.

How do you know it's not a crackpot book? All evidence you mentioned here seems to support that conclusion.

Where did you read this? "Purpose" is a very loaded word. If life has any purpose at all, it's to reproduce and propagate one's genes. Additional entropy just sounds like an inevitable side-effect of that.

It tracks, though "attaining a higher state of entropy" is just what Universes generally do it seems, given our n of 1 Universes we've started to evaluate.

Though, I'm not sure if life is the best at it, when compared to say a black hole. Some smart apes burning off fossil fuels seems pretty insignificant in comparison -- or even seeing what our own Sun does in a few seconds.

File that under, "The Earth will be fine in the long run, it's humans that are f'd" George Carlin pov. Maybe when we start building Death Stars (plural)

I read somewhere that life is more efficient at dissipating energy and faster at increasing entropy than non-living physical/chemical phenomena. Citation needed.

I think it was from Sean Caroll's book The Big Picture.

The statement is a category error, but that criticism distracts from the very valuable insight he does provide regarding entropy, life and complexity.

He did a series on minutephysics explaining it quite well, worth a watch. He does explain why complexity increases as entropy increases (with some additional qualification).

https://www.youtube.com/playlist?list=PLoaVOjvkzQtyZF-2VpJrx...

I have lost the book, but I think I read this in "What is Life? And Other Scientific Essays" by Erwin Schrödinger. If I recall, it was one of the "Other Scientific Essays."

POSIWID. Life on earth's primary "purpose" if observed from space would be to dissipate low-entropy solar radiation, using it to build temporary structures out of carbon.

It is puzzling why life isn't more common. Perhaps dissipative self-organizing structures are everywhere - stars, solar systems and galaxies themselves maintain their order by dissipating energy. They just don't look like "life" to us.

We are only relatively recently have good enough tooling to even talk about discovering bio- and technosignatures in the atmosphere of exoplanets. I'm really hoping that we will find some undeniable evidence in my lifetime.

Surely you mean accelerate entropy.

I presume the end-state of entropy would be the same (excluding ways to escape the universe).

I mean purpose is assigning too much agency, but it's relatively easy to show cells are entropy pumps - they survive by producing a lot more entropy in their environment then is recovered from dying.

The authors here are claiming, as your quote states, that biological evolution is just one instance of a more general phenomenon. I'm not sure that's contrary to the views you're expressing. You wrote:

> The expectation that life is somehow special is wrong. There is, as far as we can see, no difference in the quarks in a dog and those in a rock

But the authors' examples do include the "speciation" of minerals! As I read it, the authors describe:

- some initial set of physical states (organisms, minerals, whatever)

- these states create conditions for new states to emerge, which in turn open up new possibilities or "phase spaces", and so on

- these new phase spaces produce new ad hoc "functions", which are (inevitably, with time and the flow of energy) searched and acted upon by selective processes, driving this increase of "functional information".

I don't think it's saying that living things are more complex or information dense per se, but rather, that this cycle of search, selection, and bootstrapping of new functions is a law-like generality that can be observed outside of living systems.

I'm not endorsing this view! There do seem to be clear problems with it as a testable scientific hypothesis. But to my naive ear, all of this seems to play rather nicely with this fundamentally statistical (vs deterministic) picture of reality that Prigogine described, with the "arrow of time" manifesting not just in thermodynamics and these irreversible processes, but also in this diversification of functions.