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."<p>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.
Some reading that disagrees with Constructor Theory: <a href="http://motls.blogspot.com/2014/05/constructor-theory-deutsch-and-marletto.html" rel="nofollow">http://motls.blogspot.com/2014/05/constructor-theory-deutsch...</a><p>Looking forward to reading comments that disagree with this disagreement.
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.
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.<p>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."<p>Seems like an interesting take. I'm not convinced that it's at all useful, but it's not obviously flawed or vacuous.<p>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.
I can't follow the article.<p>I'll assume it means this:<p><pre><code> //Old theory
u = new Universe();
//TODO: populate...
</code></pre>
...<p><pre><code> //New theory
r1 = Replicator.getInstance();
r2 = Replicator.getInstance();
r3 = Replicator.getInstance();
u = new Universe(r1,r2,r3);
</code></pre>
:)
I'm not too impressed with this 'constructor theory' so far. For instance they claim:<p>>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.<p>This seems to be false, as there is no physical law preventing entropy from decreasing but there <i>is</i> a physical law which prevents the existence of a 'constructor' capable of decreasing entropy.<p>>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.<p>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.
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.<p>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.<p>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.
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?
> 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.<p>this statement is strictly untrue. it seems to assume that this behaviour is not going to be selected for, when very trivially it is...<p>natural selection isn't special to life... it applies to everything, again for obvious reasons.<p>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.
Carl Sagan once said: "If you want an apple pie from scratch, you must first invent the universe".<p>As I understand it from this article, it is saying: "Once you invent the universe, then an apple pie will exist... given enough time." ?