Open letter to Sabine Hossenfelder
Quantum physics, free will, and computability
Sabine Hossenfeller is a particle physicist who launched a campaign a few years ago to bring her colleagues’ heads out of the clouds and closer to experimental observation, to avoid getting Lost in Math. Subsequently, a talent for explaining science in an entertaining way without sidestepping complexities has led to runaway popularity for her Youtube channel.
This year, she has written an ambitious popular book about the scientific Big Picture. When she talks about physics and cosmology, she gets things right (AFAIK). But where she dips into biology, I think she displays her ignorance. She misunderstands aging completely — but that’s my bailiwick, and perhaps I’m hypercritical. Most concerning to me is that she seems unaware
That living things can learn and remember and form strategies and conclusions without neurons. Plants and paramecia learn and remember without neurons. Planaria remember what they learn even if you cut off their heads. Monarch butterflies transmit their migration maps to offspring in the 6th generation.
That there is a nascent science of quantum biology, and there are experiments suggesting that our brains are constructed so as to exploit quantum indeterminacy.
That there is a credible literature of parapsychology, with reproducible proof of telepathy and a physicist of impeccable credentials who has demonstrated the effect of human intention on what quantum physics regards as purely random.
More surprisingly (in view of her background), Sabine seems committed to the idea that quantum mechanics is a reductionist theory in which individual particle behaviors explain everything at a larger scale. As I’ve said before, a multiparticle wave function is not reducible to probability amplitudes for individual particles; rather it is a single probability amplitude in the space of all possible configurations. Thus, quantum mechanics is essentially holistic. How can we reconcile this with Sabine’s taunt: “If you say ‘holism’, I hear ‘bullshit’”?
Sabine has been effective in calling out the physics community for promoting ideas that are so abstract we can never know if they are on the right track; but she has been unaware that this same community is suppressing publication of experimental findings that are deeply subversive to current paradigms.
“The future is fixed, except for the occasional quantum event that we cannot influence.”
There is a robust literature indicating that human intention can influence the events that QM regards as “random”.
In this passage from Chapter 4, she throws down the gauntlet:
The available evidence tells us that the whole is the sum of the parts. Not more and not less. Countless experiments have confirmed for millennia that things are made of smaller things, and if you know what the small things do, than you can tell what the large things do. There is not a single known exception to this rule…I accept this as “best current knowledge”.
Reductionism, according to which the behavior of an object can be deduced from the properties, behaviors, and interactions of the object’s constituents, is…one of the best-established facts about nature….reductionism may fail in some subtle ways that I’ll discuss later.
We have never observed an object made of particles whose behavior falsified reductionism, though this could have happened countless times. We have never seen a molecule that didn’t have the properties you’d expect, given what we know about the atoms it is made of.
The human brain contains about … 10^27 atoms. Even with today’s most powerful supercomputers, no one can calculate just how all these atoms interact to create conscious thought. But we also have no reason to think it is not possible. For all we currently know if we had a big enough computer, nothing will prevent us from simulating a brain item by item.”
“In contrast, assuming that composite systems – brains, society, the universe as a whole – display any kind of behavior that is not derived from the behavior of their constituents is unnecessary. No evidence calls for it. It is as unnecessary as the hypothesis of God. Not wrong, but ascientific.”
I’m inspired to write to you because
in your new book, you make a very clear statement identifying your scientific worldview with physicalism
you indicate that physical explanations are essentially bottom up (reductionism)
you’re an open-minded person
you’ve built your reputation on a foundation of empiricism
you influence a large following of scientists and non-scientists alike
I would like to point you in the direction of a credible body of evidence that suggests that there is a non-physical realm with consequences in the physical world.
I would argue that quantum physics is essentially holistic, and that the reason that we are habituated to thinking from the bottom up is that calculations of a wave function with more than three particles (two in the cm frame) are intractable
Hence this letter is in two parts.
Part One: Evidence that what QM regards as “random” is not truly random, but is correlated with purely mental activity.
The most direct evidence was compiled by Robert Jahn and Brenda Dunn at the PEAR lab, within the Princeton University School of Engineering, during the period 1975 - 2005. During the early part of this time Dr Jahn was Dean of the School. His PhD is in physics.
In one long-running experiment, they asked students and people who walk in off the street to sit in front of a screen and try to mentally influence the output of quantum random number generator, either higher or lower. Over 30 years of data collection, the difference between “high” and “low” trials was 5 sigma.
The unique things about this experiment were, (1) that it directly examines the question whether what QM regards as “random” is influenced by a realm of thought, outside what we regard as “physical”; and (2) that the experiments were designed by someone with the highest level of sophistication in statistical methods and experimental design, also a deep understanding of quantum mechanics.
In other respects, the results were unexceptional. The effect of mind on quantum systems was replicated in the 2010’s in the lab of Dean Radin, another very competent scientist with sophisticated understanding of the pitfalls in parapsychological research. The best- established experiment in parapsychology is the Ganzfeld protocol for detecting telepathy with overwhelming statistical significance over 50 years of independent replication. This comprehensive review by Etzel Cardena summarizes 140 years of research that establishes the reality of mind-matter interactions beyond a scientific doubt.
It’s too late, alas, for Robert Jahn; but maybe you would interview Dean Radin on your podcast. Like you, he is an excellent science communicator. I think he understands your perspective and has adopted a broader one.
Part Two: Quantum theory is holistic in its essence, but our impression is skewed by the intractable difficulty of calculating anything .
Theoretical calculation is easier than experimental measurement. This is one of the things that makes theories valuable. It’s a property of theory that’s built into our scientific thinking at a deep level. But in quantum mechanics, it’s not true. We can easily measure the ground state energy of a neon atom, but the full (non-relativistic) computation is utterly intractable because the wave function lives in a 30-dimensional space. All the computer memory in the world couldn’t hold the information in this one wave function. If every atom in our galaxy stored a bit of information, that would be about enough storage capacity to record this wave function for a single atom.
Under the circumstances, what can we really claim to know about N-particle quantum systems?
The equations of Newtonian physics grow in complexity quadratically with the number of particles. In contrast, a quantum wave function for an N-particle system is an object that lives in a 3N dimensional space. If you require 1,000 pixels of resolution for the wave function, then adding each additional particle increases computational intensity by a factor of a billion. Today’s most powerful computers can map the wave function of an isolated helium atom, but anything larger is utterly intractable.
The underlying mathematical laws necessary for a large part of physics and the whole of chemistry are thus completely known, and the difficulty is only that the exact application of these laws leads to equations much too complicated to be soluble. — P. A. M. Dirac
Hence, everything we know about physical chemistry is based on quantum heuristics. We model an N-electron atom as though it were a hydrogen atom with N orbitals, constrained by Pauli exclusion, but otherwise ignoring electron-electron interactions, or treating them as perturbations. Instead of a single wave function in 3N dimensional space, we approximate with N quasi-independent wave functions in 3-dimensional space.
We model the electrons in a solid with a Slater determinant, again treating electron-electron interactions with a mean field approximation.
I don’t want to knock this approach, because it has yielded a world of insights over the last century, and physical chemistry is to some extent a true predictive science. And yet, we should be aware that we are unable to do the calculations that we would wish to do.
Thus any claim that the universe is, in principle, predictable is subject to this caveat. The computer needed to predict the behavior of even one molecule is larger than the universe.
Actual quantum mechanics is a holistic theory. The only reason we think of it as a theory about individual particles is that individual particles are all we know how to calculate.
When we observe a macroscopic object, what is it that we actually know? I would argue that the most direct answer to this question is that we are observing something about the entangled state of some 10^25+ particles. The observation creates the state. How does our observation of a rock or a chair or a house or a cloud affect the system? It certainly creates an entangled macro state, but we have no science to explore the relationship between the observed state and the individual particles that constitute the system from a reductionist perspective.
Does the holistic nature of quantum theory matter in any practical way? I think it probably does. That’s why we didn’t predict high-temperature superconductivity. That’s why we don’t understand how cold fusion works.
How have biological systems evolved to take advantage of quantum effects that physicists have yet to discover? Quantum biology is yet a very young science, but it has discovered a few extraordinary and unexpected effects. The chlorophyll molecule has been engineered by nature to use quantum tunneling to convert sunlight to electricity more efficiently than any human-engineered solar cell. Sensors in a bird’s brain precess in the presence of the earth’s magnetic field, providing real-time clues about motion and orientation.
And what is the relationship of mind to brain? When we introspect, what are we observing about the quantum state of our brain? Can thinking be described as an observer embodied within a physical system of nerves? Is this getting uncomfortably close to Cartesian ideas about a soul than inhabits a body? I offered some of my thoughts on the subject in this space last spring.
Dr Hossenfelder, you have earned a reputation as an empiricist, committed to founding all knowledge in the outcome of experiments. For you, this path has led to a paradigm in which all phenomena in the world find their most fundamental explanation in terms of microscopic behavior of particles. You outline a hierarchy that is standard in science, but rarely articulated as explicitly and clearly as you have done:
Sociology and politics emerge (softly) from psychology
Psychology emerges from chemistry and physics of the brain
Brain phenomena, like all biological phenomena, can be explained in terms of chemistry and physics
Chemical properties of atoms and molecules are a consequence of the physical properties of constituent atoms.
Thus physics of particles is the foundation of all knowledge
But more than a century ago, no less a mind than William James adopted the perspective of radical empiricism, and it led him to a very different view of the world. To him, it was obvious that his own awareness of sensory data and thoughts in his mind was the thing of which he had the most direct experience. He died a generation before the first debates about whether the mind plays a role in collapse of the wave function, but in the most direct sense, he anticipated the idea that mind must play a fundamental role in physics.
James famously argued that the human brain is not a computational system but a transponder that channels consciousness from an abstract realm and enables it to interact with matter. There is experimental support for this idea in recent observations that biological systems without neurons can learn, including paramecia and pea plants. You can train a planaria worm in a maze, cut off its tail, and when the tail regrows a head, the worm will remember its training.
You have argued that wave function collapse is a process of decoherence as a small system with a well-defined quantum state comes into contact with a larger one that has only a macro state. I’d guess that a plurality of physicists agree with you. But it is certainly a respectable position among physicists that consciousness “exists” as a different kind of entity than particles or fields, and it is consciousness that collapses the wave function. Bohr, von Neumann, Wigner, Bohm, and arguably Wheeler and Schrödinger took this position.
In light of all that we know about telepathy, about children who remember past lives, about precognition, about near-death experiences, about plants that can learn, about experience that seems to happen outside the context of a brain, isn’t it an attractive hypothesis that consciousness is a real phenomenon, apart from space and time, but interacting with physical matter?
— Josh Mitteldorf