
Constructor Theory Solves the Riddle of Life - zbravo
http://aeon.co/magazine/science/constructor-theory-solves-the-riddle-of-life/
======
powera
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.

~~~
andbberger
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](https://en.wikipedia.org/wiki/Constructor_theory#Motivations)

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

~~~
jhallenworld
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.

~~~
andbberger
It's a salient prior.

------
pizza
Some reading that disagrees with Constructor Theory:
[http://motls.blogspot.com/2014/05/constructor-theory-
deutsch...](http://motls.blogspot.com/2014/05/constructor-theory-deutsch-and-
marletto.html)

Looking forward to reading comments that disagree with this disagreement.

~~~
Xcelerate
Lubos is normally a little too ornery for me, but I thoroughly enjoyed that
post. Constructor theory (or at least that article about it), seems like
superficial nonsense. Kind of in the same way that programming languages
become bloated with concepts like "Object Factory Factories" and "Singletons"
and delegates, etc.

------
jerf
Well... it may solve the riddle of life, but that article sure doesn't explain
how at all. This is a criticism of the article, not the theory, as my point is
that the article is not describing this well enough to be critical of a theory
that I still don't have any idea about.

~~~
scrumper
I wasn't left that much the wiser after reading this either. In short, I think
"constructor", "recipe", "knowledge" are some pretty heady concepts which
could use a lot more explanation.

I _think_ what it's trying to say is that constructors are resilient (i.e.
long lived, through virtue of replication) 'structures' expressed in matter
capable of stably holding and repeatably acting on digital information. And
once you have a basic constructor, assemblages of these can provide
successively higher levels of organizational power. Their digitally error-
corrected resilience differentiates them from flash-in-the-pan analog
chemistry, and once you have that longevity of structure you can start to have
life. I think.

I don't know. I mean, yes, intuitively, life as an emergent property of
recursive layers of self-organizing structures makes more sense than life as
the continuation of a random walk through chemistry, but whatever constructor
theory is, it's not deeply explained here. What are its implications? How does
it actually compare to alternative theories?

------
dangerlibrary
Previous conception: We accept that the laws of physics must be compatible
with the observation X (in the article's case, life), but they do not explain
why X exists.

Constructor Theory: All things not explicitly forbidden by the laws of physics
can exist. The answer to "Why does life exist?" is: "because the laws of
physics do not explicitly prevent it."

Seems like an interesting take. I'm not convinced that it's at all useful, but
it's not obviously flawed or vacuous.

Sidenote: I've never felt that the existence of life was as mystifying a
physical problem as the existence of black holes, or expanding space time, or
stars. Why people are mystified by life but blithely accept the existence of
distant fusion reactors the size of our solar system is beyond me.

~~~
white-flame
"The laws of physics do not explicitly prevent space unicorns living on the
far side of the moon."

Yeah, I don't see this as all that useful, either. It also still doesn't in
any way advance discovering what process brought things into being, it only
accepts that it happened, which everybody already accepted.

~~~
dangerlibrary
We kind of already understand the physical processes that brought things into
being, though. A mix of random chance and physical laws happened to create the
right environment for hydrogen and oxygen and carbon and nitrogen to exist in
the same place at stable temperatures for a couple billion years, and we got
life. The question is "can we accept the fact that this process took place
without being designed."

Constructor theory says, in short: "Yep. We can also accept the existence of
space unicorns, for a physically possible definition thereof. Probably not on
the far side of the moon though, since we've been there and would've seen
them."

~~~
qq66
>" A mix of random chance and physical laws happened to create the right
environment for hydrogen and oxygen and carbon and nitrogen to exist in the
same place at stable temperatures for a couple billion years, and we got
life."

That sentence just skipped over the most important part of the whole question!
:)

~~~
dangerlibrary
I don't think either constructor theory or any alternative theory addresses
anything I skipped.

Either you accept that the initial state that lead to life was constructed, or
you accept that it was not constructed and are faced with the problem that
constructor theory intends to address. These theories attempt to explain why
the initial state for the universe was conducive to life/stars/black
holes/whatever - everything I described is long after the fact.

~~~
qq66
Oh, I don't think "constructor theory" answers any interesting questions. I
just think that there is a very interesting question about how we get from
primordial soup to self-replicating cells that we don't have a good answer for
yet.

------
daveloyall
I can't follow the article.

I'll assume it means this:

    
    
        //Old theory
        u = new Universe();
        //TODO: populate...
    

...

    
    
        //New theory
        r1 = Replicator.getInstance();
        r2 = Replicator.getInstance();
        r3 = Replicator.getInstance();
        u = new Universe(r1,r2,r3);
    

:)

------
contravariant
I'm not too impressed with this 'constructor theory' so far. For instance they
claim:

>In constructor theory, physical laws are formulated only in terms of which
tasks are possible (with arbitrarily high accuracy, reliability, and
repeatability), and which are impossible, and why – as opposed to what
happens, and what does not happen, given dynamical laws and initial
conditions. A task is impossible if there is a law of physics that forbids it.
Otherwise, it is possible – which means that a constructor for that task – an
object that causes the task to occur and retains the ability to cause it again
– can be approximated arbitrarily well in reality.

This seems to be false, as there is no physical law preventing entropy from
decreasing but there _is_ a physical law which prevents the existence of a
'constructor' capable of decreasing entropy.

>Moreover, it is a fundamental idea of constructor theory that any
transformation that is not forbidden by the laws of physics can be achieved
given the requisite knowledge. There is no third possibility: either the laws
of physics forbid it, or it is achievable.

Either they are saying something is achievable if and only if there is a
constructor for it, which is false (see previous point), or they are claiming
something is achievable if and only if the laws of physics don't forbid it,
which makes this 'fundamental idea' vacuous.

~~~
AnimalMuppet
If you can build a constructor for it, it's possible. OK, I'm fine with that.
If you know it's impossible, then you can't build a constructor for it. Also
fine.

But where it sounds like this is going is: If you don't know it's impossible,
then it must be possible to build a constructor for it. That assumes that
_everything_ that we don't currently know is impossible must be possible.
That's... quite an assumption.

Worse, that assumption is swept under the rug rather than explicitly stated.

Or I could be misjudging their position...

~~~
contravariant
I think there's also a (again silent) assumption that a constructor can be
constructed, which is again non-trivial, and actually seems to be false. And
if it is false then that seems like a major flaw, at least I don't really see
how a non-constructable constructor is more convenient than the physical laws
it is supposed to represent.

I also suspect you'll encounter something like the halting problem when trying
to figure out _which_ constructors aren't constructable. At worst you'll
encounter constructors where this question is unanswerable (e.g. can you
construct a constructor, which constructs all constructable constructors that
can't construct themselves?).

------
mkehrt
This...seems like nonsensical pseudoscience.

~~~
wbhart
After reading the article I was left with the distinct impression that
"constructor" is a name for something they suppose must exist to solve their
problems and that the mere act of giving it a technical sounding name allows
them to say they've solved the problem of the origin of life, since now they
may say "constructor theory solves that problem".

~~~
Nevermark
And its not even an original mistake. Our ancestors also used words (like
"god") to answer (i.e. stop asking) questions about the origin of life.

But I for one look forward to worshiping the Great Constructor.

~~~
cronjobber
Nice theory. Fly in the ointment: Our ancestors didn't stop asking, quite
obviously, given that we ended up here.

~~~
Nevermark
Actually a lot of ancestors did stop asking. I think that is established fact,
not theory, as even today it is easy to find people who disbelieve even basic
science when it contradicts a religious view.

But fortunately, as you point out, not everyone stops asking questions.

------
hyperion2010
Unfortunately this seems like a rather weak tool for addressing the issue, we
have had conceptually similar tools (though not attempt has really been made
to formalize them) for a long time, and many border on the anthropic
principle. The reason for the weakness is that there is no guidance for how
one is to go about testing whether some constructor actively violates a
physical law. In addition this doesn't at all help us delimit the space of all
possible constructors.

Fundamentally the issue is that constructor theory seems to require us to
write down every possible constructor and gives us no way to validate whether
they will work, not particularly useful from a theoretical perspective since
it is essentially equivalent to having to do an exhaustive search of the
space. True, but tautological and rather useless since it doesn't provide any
insight into the relative importance of initial conditions (or previous
history) and the fundamental forces in delimiting what is possible in any
given universe.

We want to be able to describe the probabilities of any particular
configuration of matter coming to be at some point in time in the universe as
a function of the initial conditions and the forces that govern it (statmech
can sort of do this for simple systems). This simply assigns probability 1 to
everything and leaves as an exercises for the reader how to check whether such
assignments are consistent with the laws of nature.

------
panic
A scientific theory has to do more than explain existing phenomena: it has to
make predictions which can be tested. What are some testable predictions of
constructor theory?

------
jheriko
> In short, the theory presupposes the possibility of certain accurate
> physical transformations, and these are just what no-design laws of physics
> fail to provide in their starter kit.

this statement is strictly untrue. it seems to assume that this behaviour is
not going to be selected for, when very trivially it is...

natural selection isn't special to life... it applies to everything, again for
obvious reasons.

its a very, very simple consequence of existence. those things that survive
longest survive longest. its so simple its hard to explain. its no more
complicated than the action of a sieve, which stops clumps from going through
due to physical constraint - a form of natural selection.

------
metaphorical
Carl Sagan once said: "If you want an apple pie from scratch, you must first
invent the universe".

As I understand it from this article, it is saying: "Once you invent the
universe, then an apple pie will exist... given enough time." ?

~~~
Nevermark
"Once you invent the universe, then an apple pie will exist... given enough
time."

An interesting conjecture but not exactly provable! I assert that a universe
is a necessary but not sufficient condition for apple pies.

~~~
Yen
The article is a bit hard to parse, here's my take on it

Given a universe, in which the exact arrangement of particles that make up an
apple pie is not physically impossible, it is physically possible for an apple
pie to arise through the evolution of the universe, without requiring 'outside
input'. (i.e., design or influence by some entity outside the universe).

Furthermore, while it would be stupendously unlikely for an apple pie to arise
completely by chance (imagine the odds of all the right atoms just _happening_
to collide in the right way at the right time), it's not nearly as unlikely
that some kind of self-replicator should arise, and this self-replicator could
eventually generate an apple pie, or something of similar complexity.

------
statik_42
This seems almost like a scientific way of stating Murphy's law with an
addendum: anything that can happen, will happen..eventually.

