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Kindle Notes & Highlights
by
Heinrich Päs
Read between
January 31 - April 30, 2023
Because if we pay attention to the full story, we will see that particles do not compose the world; it is the other way around.
The most fundamental description of the universe has to start with the universe itself.
As I will argue in this book, once quantum mechanics is applied to the entire cosmos, it uncovers a three-thousand-year-old idea: that underlying everything we experience there is only one single, all-encompassing thing—that everything else we see around us is some kind of illusion.
Decoherence is the agent protecting our daily-life experience from too much quantum weirdness. And it realizes the rest of Heraclitus’s tenet: “from One all things.”
cosmic history may be understood as what we experience, created by our perspective onto a fundamental “quantum reality.”
“It is quite wrong to try founding a theory on observable magnitudes alone. In reality the very opposite happens. It is the theory which decides what we can observe.”33 Einstein’s argument is known to philosophers as the “Duhem-Quine thesis”: in order to extract an experimental result from an observation, it is necessary to understand what is happening during the measurement and how exactly the measurement apparatus and our perception function. “You must appreciate that observation is a very complicated process… Only theory, that is, knowledge of natural laws, enables us to deduce the
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If theory determines what we can observe, Heisenberg thought, shouldn’t it also determine what we can’t observe?
“Opposites [such as particles or waves] do not contradict but rather complement each other.”
In the Copenhagen philosophy, the act of measurement played a crucial role. According to Heisenberg, “Everything observed is a selection from a plenitude of possibilities,” and only what was finally observed was considered “real.”42 This notion of a reality produced by the act of observation later fueled Wheeler’s speculation about our creating the universe.
Copenhagen physicists didn’t understand classical physics as a limiting case of a more fundamental quantum or projector reality; rather they saw quantum mechanics as an instrument to obtain knowledge about classical objects experienced on-screen.
According to Bohr’s and Heisenberg’s Copenhagen interpretation, quantum mechanics was no longer a theory about nature. It was a theory about the experimentalist’s knowledge about nature:
According to the Copenhagen physicists, atomic objects obtained their reality from the act of measurement. For Bohr, reality was like a movie shown without a film or projector creating it:
the struggle between Heisenberg and Schrödinger about particles versus waves boils down to the argument about whether a can of Coke is a circle or a rectangle. At some point, Bohr stepped in and judged that circle and rectangle are two complementary ways to experience the can, but we have to stick to the language of circles and rectangles and aren’t allowed to talk about cans as cylinders.
Schrödinger’s cat illustrates a “macroscopic quantum superposition” and has become the classic example of quantum weirdness ever since.
In a lecture given at the University of Chicago in the spring of 1929, Heisenberg detailed that quantum mechanics could be considered either as a noncausal process “in terms of space and time” or as a causal process beyond space and time.
What makes the projector reality special then? As we will see, it is its capability of merging several objects and even, in the extreme case, all objects in the universe into one.
the idea that matter originates from information, that “every particle, every field or force, even the spacetime continuum itself—derives its function, its meaning, its very existence entirely—even if in some contexts indirectly—from the apparatus-elicited answers to yes or no questions, binary choices, bits.”
“The point is that the universe is a grand synthesis, putting itself together all the time as a whole… It is a totality.”
“a comprehensive view of the physical world [would] come not from the bottom up—from an endless tower of turtles standing one on the other—but from a grand pattern linking all of its parts.”
we experience this fundamental unity as many separate objects.
entanglement is the reason why we seem to live in a classical reality. It is—quite literally—the glue and creator of worlds.
Bohr, who understood the quantum wave only as a description of knowledge rather than a description of reality.
Entanglement is quantum mechanics’ way of integrating parts into a whole. Individual properties of constituents cease to exist for the benefit of a strongly correlated total system. Or, in the words of string theory pioneer Leonard Susskind, “It would not make sense for a mechanic to say, I know everything about your car but unfortunately I can’t tell you anything about any of its parts. But… in quantum mechanics, one can know everything about a system and nothing about its individual parts.”
Entanglement provides the glue that allows quantum mechanics to constitute a monistic philosophy, the radical notion that there is but a single object comprising everything that exists—if quantum mechanics can be understood as a theory about nature and not, as the Copenhagen physicists maintained, a theory about knowledge.
fundamental reality is: “it is a grand synthesis, putting itself together all the time as a whole… It is a totality.”
For the Copenhagen physicists, the reality behind particles and waves was none of their business. It was the “tao that can’t be named,” the things in heaven above.
Instead of realizing that the monism embraced in ancient philosophies is indeed a crucial concept for modern physics, the Copenhagen physicists reclassified the foundation of physics as religion.
“The causal law is not an empirical assertion which can be proved or disproved by experience but the very basis of all experience.”59 Unafraid of any authorities, she “decided to fight the matter out” directly with Heisenberg.
apparent causality violation experienced in quantum processes was nothing but an artifact of the on-screen reality: “Quantum mechanics has therefore not contradicted the law of causality at all, but has clarified it and has removed from it other principles which are not necessarily connected to it.”
quantum mechanics consisted of two processes: first, the deterministic smooth evolution of quantum waves according to Schrödinger’s equation, and then the sudden indeterministic collapse during the measurement collapse.
Hermann argued that quantum mechanics in fact provides the causal reasons for the state of an observed system, albeit only in relation to the specific observation, and that the nondeterministic feature was a property of the projection, not of the film roll.
Rather than confining the formalism of quantum mechanics to our everyday prejudice, as attempted in hidden variable theories, the many worlds interpretation would expand the realm of reality.
Hidden variable theory essentially strives to confine the potentialities of quantum mechanics to comply with our perceived notion of reality. The many worlds interpretation instead widens our notion of reality to comply with what quantum mechanics predicts.
IF “ALL IS ONE,” WHY DO WE EXPERIENCE THE WORLD AS plurality? Where do matter and structure originate, and what actually happens during a quantum measurement?
“A new scientific truth does not triumph by convincing its opponents and making them see the light,” Max Planck wrote, “but rather because its opponents eventually die.”
“[Einstein] put his feeling colorfully by stating he could not believe that a mouse could bring about drastic changes in the universe simply by looking at it.”
Ironically, Everett’s theory became famous as the “many worlds interpretation” of quantum mechanics. In fact, it was an entirely monistic description of quantum reality.
Bohm argued that while in classical physics “the world can be analyzed into distinct elements,” quantum physics implies “the indivisible unity of all interacting systems.”
One can argue that physics doesn’t describe reality full stop; that was Bohr’s approach. Or one can try to confine physics to what is experienced, as Bohm advocated. Or, finally, one can extend the notion of reality to what the equations of quantum mechanics produce.
Everett proposed a quantum mechanical approach to everything that would start with a universal wave function for the universe:
“quantum cosmology,”
Everett took quantum mechanics seriously as a theory about nature, not as a theory about knowledge, as the Copenhagen interpretation suggests.
According to Everett, in a quantum measurement, all possible results are equally realized, albeit in different “relative states,” in his own terms, or in parallel universes or “many worlds,” in Bryce DeWitt’s later rephrasing.
Since the quantum potentialities do not collapse into a single outcome, no collapse needs to be transmitted with infinite speed.
Schrödinger had pondered such implications, only to dismiss them at once: “The idea that… all really happen simultaneously seems lunatic… just impossible.… If the laws of nature took this form… we should find our surroundings rapidly turning into a quagmire, or sort of featureless jelly.”
Everett went as far as comparing the observer with an amoeba that reproduces via cell division, or “splitting,” and concludes, “Our amoeba does not have a life line but a life tree.”
As soon as Everett finished his thesis, the problems began. “No one could fault his logic, even if they couldn’t stomach his conclusions… The most common reaction to this dilemma was just to ignore Hugh’s work,”
“quantum cosmology”
While Everett’s theory doesn’t provide any experimental signatures different from the Copenhagen interpretation, it is essential to make sense of modern physics, from cosmology to its most advanced technical applications. Yet, despite such virtues, Everett’s interpretation remained an outsider’s view.
Everett put this point straight, when asked about it in 1977 by the young French physicist Jean-Marc Lévy-Leblond: “The question is one of terminology: to my opinion there is but a single (quantum) world, with its universal wave function. There are not ‘many worlds,’ no ‘branching,’ etc., except as an artifact due to insisting once more on a classical picture of the world.”
