What Is Constructor Theory? | Hacker News Reader

What Is Constructor Theory?

constructortheory.org

32 pointsSchiphol21 comments

Maybe a good start to something, but this page doesn't get deep enough into it to show why this is a worthwhile framework.

Did you see the Research page?

The menu icon didn’t show up until I turned my iPad to portrait. The Research page takes a long time to load.

So weird! I'm on a desktop. The research page looks like it has loaded, and looks as if they still don't have anything to report... for several seconds.

I recently read an interview with one of the website creators and it was fascinating: the basic premise is to reason about physics from the perspective of what is impossible/fixed.

The example given in the interview was relativity, which arose when Einstein asked the simple questions “what if c IS fixed?” (it was an open question at the time) and “what if only light can travel at c?”

Mathematical treatment of those questions led to SR and SR led (eventually) to GR.

It’s an intriguing approach: posit a fixed limit or impossibility and see where the math takes us (inventing/applying new math as necessary). Some avenues will be useless, others may be fruitful.

After a quick skim the constructor theory seems like restating laws of physics as logical relations instead of functions.

So instead of saying f(3)=4 you say relation f is fulfilled for arguments 3 and 4.

Is this all or did I miss something?

Relations are more general and expressive, but ultimately you can always turn a relation into a function of 1 more dimension, so don't think it's a breakthrough.

From a brief read (there aren't many details on the website) it sounds like they are trying to reformulate physics along the lines of object orientation. I'm not sure how this is going to handle fields (such as gravitational fields) or how this is supposed to be better.

"With support of the Templeton World Charity Foundation". The Templeton is highly controversial:

https://en.wikipedia.org/wiki/John_Templeton_Foundation#Rece...

How is this different from Lagrangian mechanics? It seems as though the author is substituting "action" in Lagrangian mechanics for "task" and calling it a new theory.

Dunno, but I wonder if there are even "tasks" in CT that don't use energy. I think even a proton will lose energy through redshifting.

I think they are trying to explain the connection between the past and the future. Classical models only describes the effect of the past into the future.

At first I thought it was Constructal Theory, a theory that is about flow of anything, people, heat, etc., by Andre Bejan [0], a well-known engineer at Duke.

Constructor Theory has piqued my interest in terms of solving problems or framing problems by what is possible as opposed to what is impossible or excluded by a physical law.

[0] https://mems.duke.edu/faculty/adrian-bejan

Quanta also had a recent article about this:

https://www.quantamagazine.org/with-constructor-theory-chiar...

Apologies for a stupid question, but how can you roll a dice without using any energy yourself? Or is it meant to work in some model where there is no such thing as energy (as opposed to the one when you need to lift it)

Is it just my browser or is the research page empty?

I didn’t know it was there. The menu didn’t show in landscape on my iPad. ‘Research’ takes some time to fill the page.

>Its fundamental statements are about what tasks are possible, what are impossible, and why. This allows one to incorporate more of physical reality, including entities, such as information, that have inherently been regarded as approximate and derivative as a result of the traditional physics take on things.

This is a typical crank website that tries to pass off metaphysics as physics.

>The researchers are David Deutsch, Chiara Marletto, and collaborators in Oxford Physics, Wolfson College, ISI Turin and CQT Singapore.

Great, now Oxford is running crank websites...

why? You don’t explain.

I'd agree that at first glance this reads like crank material and the question to answer is "why not?" instead of "why?". It is extremely vague and doesn't parse into anything that seems meaningful.

If something seems that way to you, and you want to say to others that it seems that way, you could explain why.

It’s not like it was developed by random nobodies, and it’s not like the default assumption should be that some work is the result of cranks (the default assumption should be agnosticism towards it)

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

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

The implication is that almost any practicing physicist would parse this as crank-ish, so we can discuss it operating from the shared position that it needs to be defended to be worth spending time on. Similar to how most physicists are not going to spend any time responding to random crank emails, because they parse as cranks; the burden of credibility is on the writer.

Credentials offer some credibility, but imo not enough to make this seem worth spending time on.

Anyway, if I had to put the criticism into words: the entire page is weird jargon that doesn't appear to solve any problems that we have, puts a simple problem into inscrutable metaphysical terminology, and the authors didn't feel like they needed to provide any examples of their model being useful or providing any insights. So my reaction is to ignore it until they do the work of showing why we should care.

I don't really get constructor theory, but if this is a crank website it has to be the one with the best pedigree.

David Deutsch has done a lot of impressive work, like coming up with the first universal quantum algorithm and providing a model that proves quantum mechanics is local.

I'm not basing my judgement on the pedigree, I'm basing it on the content. What constructor theory is about is assigning and re-assigning concepts and language to existing physical theories. That's called "metaphysics," a practice that believe it or not predates physics. (Philosophers have been formally assigning concepts and language to informal physical theories long before the first formal physical theory was articulated.) It's not like Deutsch is in bad company, Aristotle also wrote about metaphysics.

Nonetheless, that does nothing to change the fact that crank websites almost always share three elements: they are works of metaphysics but claim to be physics, they have way more popular writing than academic writing (in this case, see the size of the media page vs the empty publications page), and they have a website advertising them (that's actually pretty unique to cranks, for some reason). I don't really have an axe to grind, it's just that the linked page is a typical crank website.

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