Constructor Theory: A New Explanation of Fundamental Physics - Chiara Marletto and Marcus du Sautoy

Constructor theory holds promise for revolutionising the way fundamental physics is formulated and for providing essential tools to face existing technological challenges.

Physicist Chiara Marletto proposes a new way of thinking about laws of nature. Thinking about which laws are possible or impossible may generate an alternative way of providing explanations, and therefore new scientific theories.

In this talk, Chiara is in-conversation with Marcus du Sautoy to explain this fascinating, far-reaching approach (known as Constructor Theory) which holds promise for revolutionising the way fundamental physics is formulated and for providing essential tools to face existing technological challenges, from delivering the next generation of information-processing devices beyond the universal quantum computer to designing AIs.

Chiara Marletto is a Research Fellow working at the Physics Department, University of Oxford. Within Wolfson, she is an active member of the Quantum Cluster and of the New Frontiers Quantum Hub.

Her research is in theoretical physics, with special emphasis on Quantum Theory of Computation, Information Theory, Thermodynamics, Condensed-Matter Physics and Quantum Biology. Some of her recent research has harnessed a recently proposed generalisation of the quantum theory of information — Constructor Theory — to address issues at the foundations of the theory of control and causation in physics. These include applications to defining general principles encompassing classical, quantum and post-quantum theories of information; and to assessing the compatibility of essential features of living systems, such as the ability to self-reproduce and evolve, with fundamental laws of Physics, in particular with Quantum Physics. They also include the definition of a new class of witnesses of non-classicality in systems that need not obey quantum theory, such as gravity; and a scale-independent definition of irreversibility, work and heat, based on constructor-theoretic ideas.

Marcus du Sautoy is the Charles Simonyi Professor for the Public Understanding of Science at the Oxford University, a chair he holds jointly at the Department of Continuing Education and the Mathematical Institute. He is also a Professor of Mathematics and a Fellow of New College. He was made a Fellow of the Royal Society in 2016. In 2006 he gave the CHRISTMAS LECTURES, entitled THE NUM8ER MY5TERIES.

This talk was filmed on 27 May 2021.

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[proximacentaur]

Really interesting. I'd suggest using the YouTube 'chapters' feature to make the structure of the discussion more explicit and navigable. There were some great nuggets in there. I like the conversational style as an alternative to PowerPoint driven lectures. Hope to hear more on this subject.

[shayneoneill]

As best I understand it, Constructor theory isn't so much a physical "theory" in the same sense as relativity or QM is, rather its more a methodology of doing physics, a heuristic, that is hoped to uncover new physics. Its a *very interesting* methodology, and as a philosophy grad, I'm rather fascinated by it, because they appear to be using that trusty old philosophy trick of taking hard to answer questions and flipping them on their head and sayiing "Ok, approaching this question head on is proving rather difficult. So lets look at *wrong* answers (counterfactuals), and start using them to carve out a smaller search space for the right answer.This ties in with information theory, and my understanding is the theory provides a way to bridge information theory, which is reasonably well understood, your computers are based on it, into physics via those counterfactuals. It seems to be that they've taken that philosophy (and math!) observation that processes essentially are a transformation between an input to an output space, they are essentially a function (For instance addition transforms an input space of two numbers into an output space of one number). So if we apply this to physics, physical processes transform input states to output states, and its that observation that this appears to be living.

[SuperGnarley]

Chiara Marletto's work is philosophically loaded and can be hard to understand for those who aren't familiar with the work of people like Karl Popper, David Deutsch and John von Neumann. I see many criticisms in the comments, so I just want to urge you to consider this fact before dismissing her work completely.

[palfers]

17 minutes in and I'm still wondering wtf this new theory is.

[nicholastaylor]

Despite what history might suggest, philosophy cannot make anything happen or stop anything from happening. However, something does stop impossible things from happening. How exactly does energy conservation work? Maybe we subconsciously think in terms of money conservation, but this requires exact measurement and the only way that can happen is if money consists of discrete units, so measurement is the same as counting. Say there's a machine that delivers a teddy bear if you put in 100 coins. If you have only 99 coins then however much you try - no teddy bear. If you can borrow a coin then you can tunnel through and get the bear, put you have to make good the debt. So what is it that actually, as opposed to in principle, stops the impossible from happening? Alternatively, maybe lots of impossible things do happen, but on such a small scale that they average out or cancel out before an effect emerges at any level we can measure. Richard Feynman presented an idea of this kind in his lectures explaining reflection of light. Then you have to explain what is special about the result, least action or whatever, or how adding up immaterial 'amplitudes' actually makes something material happen. That the math works out so well must be telling us something.

[Bestape]

Is there a "counterfactual" :o) more fundamental than (Am I alive or am I dead?){I'm thinking therefore I am.}?

[larrylar]

I still don't understand any better why they do construction during traffic hours.

[rexis]

I listened to the lifeboat analogy over and over, but I still don't understand what point she's trying to convey. It seems very obvious why we would have a lifeboat on a ship. In addition to the physical forces like gravity and all momentum, we must follow biological imperatives. Preservation of life is a biological imperative. Our brains evolved to store memory so we could learn from history and avoid accidentally killing ourselves in the future. I am assuming the first lifeboat wasn't invented before the first sunken ship.

[GlynWilliams]

Interesting but for me, it's difficult to grasp.

[geoffreymak]

An interesting idea, but what have they discovered from this theory? Any new predictions? I hear her giving new names to old concepts but not much else…

[RupertBruce]

This reminds me of the change in thought process needed for test-driven development (TDD). The tests are the counter-factuals and define what the code should do but the implementation is subject only to the constraints of the system as long as it passes the tests.

[circadian_axis]

I wish we had more examples and demonstrations to follow along with

[Gringohuevon]

As a squirrel would say. A lot of noise but no nuts

[miloblue]

After listening a while, and not finding the new theory, I think the title might better read: 'Philosophical Objections to Physics Theories'

[bntagkas]

i have listened to several presentations about constructor theory, in which all have failed to simply explain what it is and what its trying to do and how to achieve that. there are 2 possibilities: one is that this woman and others into it are entirely incompetent, how do you expect to redefine physics if you cant even explain properly what you are trying to do, other possibility is and more likely in my book, this is an actual scam, its nonsesne, and trying to get funding to those few who are "working" on it. by how this theory is so early their creators havent been able to explain it properly a single time, let alone produce a single result, yet have a disproportionate time in media giving interviews about it, i think its more likely this is a scam trying to get attention and confuse not smart money men into investing in it.

[julyanjohns]

i've spent 50 years studying different scientific areas of interest and have been able to get an understanding of them over time. constructor theory has been going for years now and still no one can define it, explain what it actually is, or give concrete provable examples.

it's classic emporor's new clothes, and it's embarrassing for the RI to treat it like it's a true theory. it's like chiara's vanity project that got out of control and no one wants to admit it's vague bollox without any systematic foundation or disprovable axioms.

[fritsgerms]

Very grateful for the RI channel. Most content is incredible and I have bought many books of the speakers. But I don’t like this format as it’s not structured and I found the interviewer to be distracting. This is meant as constructive feedback.

[_vicary]

Why would I feel like these two people doesn't even know what they're talking about? The ungrounded excitement, the inaccurate terminologies... Am I the only one being dump here?

[rogerfroud]

I'm afraid that's just word soup to me. It's way too abstract for me to have any idea of what they're talking about. Maybe it's useful... who knows...

[MegaJohny]

Pretty lady with pretty name with a lot of words, but man.. I do not understand half of it and can't comprehend at all how all of this explains anything of fundamental physics.
On what merits does this theory actually stand?