Can the mind fake the universe?

Objective reality and the laws of physics themselves arise from our observations in accordance with the new concept, which turns what we consider to be fundamental.

Sophie Hebden
FQXi Awardees: Markus Muller ¹
January 18, 2019


Creation of the cosmos.
Credit: Yuri Akurs, iStock

Marcus Muller could have been mistakenly accused of being the greatest individualist in the world. The radically new view of quantum physics on reality, which he proposes, seems to lead to the fact that the perceived world emerges from our observations. He admits that this is a very difficult idea to understand. “No one has yet come up with a science fiction story that somehow illustrated it,” says Muller, “from our theory, it follows that only observations are fundamentally real.”


Marcus Muller
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Muller , who works at the Institute for Quantum Optics and Quantum Information in Vienna, Austria, and his colleague and philosopher Michael Caffaro from the University of Western Ontario, Canada, question one of our basic assumptions: reality is objective and independent of us. Mueller and Kuffaro do not argue that the world is illusory or unreal, but argue that there is something more fundamental behind this, and that their approach can explain the origin of reality and how fundamental physical laws arise.

Quantum theory has already made physicists take the role of an observer seriously. For example, before we measure a quantum system, it can have contradictory properties, for example, be in two different energy states. When we make observation, we force the system to assume a certain state, associating the act of observation with reality itself. Muller and Caffaro argue that they simply follow this path, bringing it to its logical conclusion. Their goal is to develop a basis for describing reality without assuming the existence of ordinary objects with properties determined by physical laws ² . But how to solve the ambitious task of building the Universe without any building blocks or instructions for assembling it?

“What does mathematics mean, that there are no laws of nature? It's like asking, what if you only have math? Could this give you something that allows you to predict what you will see, that is, some probabilities of observation, without assuming anything else? ”Says Muller,“ This was my starting point. ”

A mathematical method that can help do this is already available. The concept of "algorithmic probability" is already used by those who work on artificial intelligence and machine learning. It describes the probability of observation occurring across the full range of possibilities, and programmers use it to create robots that can “learn” from observing the environment and make decisions based on past results ³ .

Dump in the brain

Using this approach, Muller received a coherent description of reality from the descriptions of sets of observations made one after another. He begins with an observation that is coded in some way. This method itself does not matter, so let's say we use binary strings with zeros and ones. Observation can be a dump of data at some point in time, describing your state as a long string of bits. Muller borrows a mathematical tool from the field of artificial intelligence and asks: how likely is it that a random computer program will produce these bits by pure chance? This is called the algorithmic probability of this observation.

Muller postulates that what is happening depends on the algorithmic probability due to what has been observed in the past, and argues that this process can shape reality itself. New observations that do not fit into observations in the past, perhaps worlds with five or six dimensions are discarded because their probability is much smaller than the observed world with three spatial dimensions. Observations are consistent with what we have seen in the past, and which correspond to the description of the world in the usual sense, with the usual laws, are the most likely. Consequently, from our observations we get the "emergent world" ⁴ .

“It turns out that algorithmic probability is a very useful concept,” says Muller. Physical laws and patterns arise in the same way as the correct answers that robots give as a result of learning. “Laws tend to stabilize, and you observe these patterns around you and the world with such laws,” Muller explains. “It has the same mathematical basis.”

Renato Renner , a theoretical physicist at the Federal Institute of Technology, Zurich, Switzerland, notes that in physics there is a long history of attempts to formulate theories from the first person ⁵ . But unlike most attempts, Müller managed to develop a “well-defined theory, within which non-trivial results can be obtained,” Renner says. “This is just great!”. "Speaking simply, Muller provided a quantitative version of Occam's razor : it assigns high probabilities to future possible events that have the simplest explanation."

Boltzmann brain

Along with explaining why the laws of nature exist at all, Muller's approach may also solve some notorious puzzles in cosmology and quantum theory. One of the strangest is known as the " problem of the Boltzmann brain ." This concept dates back to the end of the 19th century, when the physicist Ludwig Boltzmann published a theory stating that the entropy or disorder of a closed system always increases. Think of the hot coffee in the drawer: the mess in this system will increase over time, as the heat energy of the coffee will dissipate in the surrounding air. But there is always the possibility that part of the system will fluctuate from disorder to order.

Boltzmann believed that the extraordinary complexity of life on Earth, including our brain, is the result of these random fluctuations, and that they can occur anywhere in the Universe. He predicted the emergence of self-aware entities, later called the Boltzmann brains, spontaneously appearing and disappearing. What is even more strange, cosmologists in recent years have calculated that many models of the Universe assume that the number of Boltzmann brains should significantly exceed the number of normal human ones. How can you be sure that you are not a Boltzmann brain, and that your next appearance will not occur in the depths of space?

Mueller's theory gives an encouraging answer: to continue to exist as usual on Earth is much easier than suddenly being in space. And if something is easier in the information-theoretic sense, then the algorithmic probability says that it is more likely.

Ideas are not yet fully developed - Muller has not published them in a peer-reviewed journal. But the concept aroused great interest, and invitations to the conference flooded. Rob Speckens , a theoretical physicist at the Perimeter Institute in Canada, believes that the theory of algorithmic information will find many applications in physics in the future, and applauds Muller for being one of the few people who accepted the challenge. “This is very original and suggestive material,” he said.

But in theory there are rough spots, said Rudiger Schack , a mathematician from Royal Holloway, University of London, UK, who works on an alternative interpretation of quantum theory, which also gives the observer a central role, called QBism (on wiki ). Although Shaq admires the mathematical rigor of the project, he is concerned about the lack of a clear definition of agents — people observing in Müller’s theoretical constructs. "The agents of Muller's theory are strangely reduced entities defined by a random process," says Schack. "The defining feature of agents should be that they make choices and act." In Müller’s theory, by contrast, the concept of action, as well as the world in which agents operate, are secondary consequences of the theory. “It doesn't suit me,” summarizes Shaq.

Müller agrees that the concept of “agent’s actions” is not part of the fundamental description in his theory, but he doesn’t see any disadvantage in this. “The choice of action is a secondary concept that should not be a fundamental part of any physical theory,” says Muller, “Just like emotions or free will. This view is consistent with traditional thinking, for example, in cosmology. "

Renner, who saw the preliminary version of Muller’s work, claims that this is one of the most interesting articles he has read in the last couple of years ( arXiv: 1712.01826 ⁶ , a short version of the article arXiv: 1712.01816 ) that makes one think. “In view of the conceptual problems that we face in our current physical theories, especially in quantum theory,” says Renner, “such radically different approaches, in my opinion, are extremely necessary.”

Translation Author's Notes

1. FQXi - Virtual Institute for Fundamental Research. It supports research in the field of fundamental physics and cosmology through the allocation of grants. More than $ 100,000 was allocated to support this project.

2. The author of the article, following the developers of the theory, uses the term objective reality, but it is more likely a reality perceived by sense organs, described by the laws of physics. Initially, the theory introduces definitions of two types of existence of objects: P-existence and M-existence. On the basis of P-existence, a P-world is defined, which can be interpreted as the existence of objective reality in the metaphysical sense of this concept. M-existence can be generally understood as the existence of some kind of universal computing environment, which, when applied to a human observer, can be interpreted as the computing neural network environment of the brain. Although the authors of the theory do not carry out such parallels in an explicit form, and generally try not to abuse wide generalizations in their work, which is typical of works on a similar subject.

3. Perhaps the approach outlined in the article will interest specialists working on the problems of AI, for this reason the hubs included “Artificial Intelligence” and “Algorithms” hubs. On Habré, on the topic of algorithmic complexity and algorithmic probability, there are quite a few publications from which the publications of the user aideus on the use of these concepts in the field of AI are highlighted, see 1 , 2 , 3 . Perhaps all this is of little relevance in the light of recent advances using ANN in the development of AI, however.

4. Emergent in the sense of the emergence of a new holistic quality, previously absent in parts.

5. The most close in spirit to this work are the publications of A. Kaminsky on subjective physics . In general, this topic includes works and discussions related to the role of the observer and, in particular, his consciousness in physics, starting with discussions on the issue of measurements in the CM during its creation, and ending with the prophecies of Uncle Roger :) in our time. According to the author of the translation, the problem of the observer has a substantially interdisciplinary character, and cannot be fully solved only within the framework of physics.

6. The article turned out to be somewhat watery, as is sometimes the case with articles of popular science :), so for those interested, added the translation of the abstract of the work itself: