The Case for Strong Emergence by Sabine Hossenfelder

Dear Sabine,

Because you are by far my favorite author on the curious state of current physics, and because I would love to have your comments on my essay, I'm a little at a loss how to respond to this beautifully-written piece. Though I don't disagree with you at any point, what was in my mind throughout was your blog-post from a couple years ago on "The Unbearable Lightness of Philosophy." Actually (as a philosopher) I'm very pleased that you take philosophical arguments seriously. But really - free will?

Surely the conscious decisions we make are the result of neurons firing in our brains, or more generally, the result of things going on beneath the level of our self-awareness. That seems like a very good thing to know about ourselves, if it makes us a little more humble. And if there were any meaningful issue about our choices being "free" - which I doubt - you'd think this is where it would arise.

But I can't see why it makes any difference to anything whether the behavior of neurons is predictable from physical principles. It's hard to see how it could be, if it's not even possible to predict when an atom will emit a photon. But what does it matter whether or not what happens in my brain is computable?

I have no problem with reductionism - except for the "ism" part. That seems to imply that this is the only kind explanation science needs, which is obviously wrong. Take biology, for example. I see no reason to doubt that everything that happens in a living cell is done by the laws of physics. On the other hand, none of these very complex molecules and patterns of interaction would exist if it weren't for the ability of cells to replicate themselves and so evolve. Nothing like this happens in physics or chemistry, so it's clearly "emergent." But that's not because it's independent of the laws of atomic physics. On the contrary, if those laws weren't so precisely uniform and reliable, self-replication would be inconceivable.

So my question is, how does distinguishing between "weak" and "strong" emergence contribute to our understanding of situations like this? I wouldn't call self-replication a "truly new fundamental law," but it is a truly fundamental functionality, on which a whole new world of possibilities is founded. It's completely new, and also completely dependent on lower-level functions.

In my current essay I try to imagine the foundations of physics in a similar light, asking about the functionality of a universe that's able to define, measure and communicate all its own information. It would mean a lot to me to know if the argument of my first three pages makes sense to you.

Conrad

Dear Sabine,

I looked for your paper because I read and enjoy your backreaction blog, so I felt your astute science writing would be insightful.

Although you acknowledge that modern theoretical physics "is almost certainly incomplete" you avoid venturing into "what" it is that is more fundamental than the well-known 25 fundamental SM particles.

The discussion of how "emergence" is defined in this context was enlightening, and the examples in condensed matter 'verrry interesting (but not fundamental)'.

Here I think that the examples of strong emergence should consider cosmology, i.e. General Relativity. This is a relevant issue for insight into the research topic. I am certain that causality is a fundamental property of particles, as Seiberg has found. So I began my essay by considering the well-founded causal formulation of particles as given by the No-Boundary Wave Function.

I also discussed the fundamental requirements to establish consistency between GR and (causal) particle theory. But in your essay you suggest (without evidence) that non-renormalizable theories are "sick". But the only reason that renormalization is used is that L'Hopital's Rule doesn't work- the mathematical singularity assumed forces an infinity/infinity situation. Of course, the singularity also compels one to arbitrarily assign quanta and scalar metrics (mass and energy).

In short, the current theory violates mathematical 'laws' which there is thus strong motivation to correct... a very good starting 'point' is to not assume a particles representation geometry is a point.

It turns out that all of these criteria can be met at once, but yes, you have to let go of renormalization. The traditional approaches that keep it and seek unification via new particles just don't work out.

That said I invite you to read and comment on my essay: https://fqxi.org/community/forum/topic/3092 and hope that its insights spark an interest.

Best,

Wayne Lundberg

p.s. as a footnote, I am sure that a person's perception of free will is best discussed in the context of particle theory by considering the scale of space-time averaging. Clearly weak-scale particle theory has little bearing since the quantum algebraic states average out at micro-condensed matter scales, long before a human scale. Consider again, if you will, to be fair, just how much free will really means when you use a space-time average of say, 2 Earth orbital diameters and 10000 years. That yields a rather different result, no?

The analogy to particle theory works pretty well when you compare a human's decision tree at, say, an intersection. Compare that to a particle interaction's "channels".

Dear Sabine,

This is a well-written essay that uses examples and a sense of humor to let the reader "in".

First a small technical point, when you say "energy" you really mean "energy density". The person who says, "go" and the person who pushes the bottom use more energy than the collision between two protons at CERN, but energy density is far higher with the protons.

Now the major problems: Radioactive decay is independent of atomic interactions (except for cases like electron capture). There is a disconnect between the first two energy density or resolution levels, namely: nuclear and atomic. There is a difference between sound, wind and thermal vibrations, which cannot be seen at the atomic scale, collisions due to sound and thermal vibrations would be the same without information of a collective mode. Any sound or electromagnetic wave that is orders of magnitude larger wavelength than the atomic scale would have the same problem. The conservation of linear and angular momentum seen in fluids would have a similar problem. At the atomic level all is reversible, a hydrogen atom at the ground state returns to a hydrogen atom in the ground state with no record of the thermal dynamic state of the collective.

Sincerely,

Jeff Schmitz

Hi Dr Sabine Hossenfelder

Wonderful start... "As everyone knows, physicists have proved that free will doesn't exist. That's because we are made of tiny particles which follow strict laws, and human behavior is really just a consequence of these particles' laws. ..... nice flow and good logic.... Best wishes to your essay

Here in my essay energy to mass conversion is proposed................ yours is very nice essay .... I highly appreciate hope your essay and hope for reciprocity ....You may please spend some of the valuable time on Dynamic Universe Model also and give your some of the valuable & esteemed guidance

Some of the Main foundational points of Dynamic Universe Model :

-No Isotropy

-No Homogeneity

-No Space-time continuum

-Non-uniform density of matter, universe is lumpy

-No singularities

-No collisions between bodies

-No blackholes

-No warm holes

-No Bigbang

-No repulsion between distant Galaxies

-Non-empty Universe

-No imaginary or negative time axis

-No imaginary X, Y, Z axes

-No differential and Integral Equations mathematically

-No General Relativity and Model does not reduce to GR on any condition

-No Creation of matter like Bigbang or steady-state models

-No many mini Bigbangs

-No Missing Mass / Dark matter

-No Dark energy

-No Bigbang generated CMB detected

-No Multi-verses

Here:

-Accelerating Expanding universe with 33% Blue shifted Galaxies

-Newton's Gravitation law works everywhere in the same way

-All bodies dynamically moving

-All bodies move in dynamic Equilibrium

-Closed universe model no light or bodies will go away from universe

-Single Universe no baby universes

-Time is linear as observed on earth, moving forward only

-Independent x,y,z coordinate axes and Time axis no interdependencies between axes..

-UGF (Universal Gravitational Force) calculated on every point-mass

-Tensors (Linear) used for giving UNIQUE solutions for each time step

-Uses everyday physics as achievable by engineering

-21000 linear equations are used in an Excel sheet

-Computerized calculations uses 16 decimal digit accuracy

-Data mining and data warehousing techniques are used for data extraction from large amounts of data.

- Many predictions of Dynamic Universe Model came true....Have a look at

http://vaksdynamicuniversemodel.blogspot.in/p/blog-page_15.html

I request you to please have a look at my essay also, and give some of your esteemed criticism for your information........

Dynamic Universe Model says that the energy in the form of electromagnetic radiation passing grazingly near any gravitating mass changes its in frequency and finally will convert into neutrinos (mass). We all know that there is no experiment or quest in this direction. Energy conversion happens from mass to energy with the famous E=mC2, the other side of this conversion was not thought off. This is a new fundamental prediction by Dynamic Universe Model, a foundational quest in the area of Astrophysics and Cosmology.

In accordance with Dynamic Universe Model frequency shift happens on both the sides of spectrum when any electromagnetic radiation passes grazingly near gravitating mass. With this new verification, we will open a new frontier that will unlock a way for formation of the basis for continual Nucleosynthesis (continuous formation of elements) in our Universe. Amount of frequency shift will depend on relative velocity difference. All the papers of author can be downloaded from "http://vaksdynamicuniversemodel.blogspot.in/ "

I request you to please post your reply in my essay also, so that I can get an intimation that you replied

Best

=snp

Dear Sabine Hossenfelder

Just letting you know that I am making a start on reading of your essay, and hope that you might also take a glance over mine please? I look forward to the sharing of thoughtful opinion. Congratulations on your essay rating as it stands, and best of luck for the contest conclusion.

My essay is titled

"Darwinian Universal Fundamental Origin". It stands as a novel test for whether a natural organisational principle can serve a rationale, for emergence of complex systems of physics and cosmology. I will be interested to have my effort judged on both the basis of prospect and of novelty.

Thank you & kind regards

Steven Andresen

Dear Sabine Hossenfelder,

i am glad and amused that you came to the conclusion that it mustn't be the case that the behaviour of particles completely reigns over your thoughts.

It is funny what people are able to believe when extrapolating some knowledge about nature. And your introductory sentence from your abstract is funny too, in my humble opinion.

Reminds me of a kind of self-conversation like this

"Once I thought my thoughts about particle physics were completely determined by particle physics... but then I realized that my toughts about mathematics were completely determined by mathematics, because I realized that mathematics and particle physics are one and the same".

"So, now I know that my toughts about mathematics are completely determined by particle physics and vice versa, since I realized that my toughts about rules are completely determined by rules.. but then I realized that my thoughts about thoughts are completely determined by my toughts ... and now I conclude that particle physics is completely determined by my thoughts and that solipsism is true."

Hi Sabine,

very interesting essay.

I have two comments though:

First I disagree that reductionism means that "Large things are made of smaller things", I would argue that more fundamental things can actually be bigger than less fundamental things, see my essay.

More important, though, your essay got me started to rethink what really is meant by „strong emergence". So while I initially agreed with your definition of strong emergence meaning physical laws that can not be derived from a more fundamental theory I'm now wondering how this corresponds to the extreme case of strong emergence I'm dismissing in my own essay, namely that the emergent theory could allow for phenomena that are strictly forbidden in the more fundamental theory, as, for example, the occurence of a biological organism being able to run faster than the speed of light. Could such a case of strong emergence be justified by the example you are providing? Am I misunderstanding „strong emergence"? Are there different kinds of strong emergence? Or is your example actually a subtle case of weak emergence? One may argue for this conclusion by objecting that your argumentation is purely mathematical, for example there might exist a physically (albeit not mathematically) equivalent theory which would allow for the continuation from higher to lower resolution missing in the original model.

Best regards! Heinrich

quote

Effective field theories work with quantum field theories, that is the type of theory that we

presently use to describe nature at the highest resolution probed so far. The key equations of the

framework (the "renormalization group equations") connect a theory at high resolution with a

theory at low resolution. That is, the theory at low resolution is always weakly emergent. It can

be derived - at least in principle - from the theory at high resolution.

In practice the derivation of the low-resolution theory can only be done for simple systems,

but from a philosophical standpoint this isn't relevant. Relevant is merely that physicists do

have equations that define the theory on low resolution from the theory at high resolution.

Effective field theories can fail [9] in the sense of methods becoming inapplicable, and there

are certain theorems that can fail (such as the decoupling of scales), and there are some approximations

that might become invalid (such as weak coupling), and so on. These are practical

problems for sure. But in principle, none of this matters. Because even if we don't know how

to do a single calculation, the theory is still there. It doesn't go away

end of quote

Please describe how you would apply these criteria to the early universe, i.e. the pre Planckian to Plackian regime

I did an essay due to these considerations, too

You can review it, and I welcome your comments. I put it in December 21st

thanks for your essay. it was a good read

Andrew

Hi Sabine,

Nice essay! I'm a bit skeptical that anything we tend to call "free will" has anything to do with any of this, but you still make many interesting points about strong emergence and reductionism. (For a nice modern take on Free Will, I highly recommend Jenann Ismael's new book, "How Physics Makes us Free". )

Two questions for you:

1) The only vague overlap between our essays is the paragraph where you argue that boundary constraints aren't a counter-example, because in the case of a conducting plate you can replace the boundary constraint with the microscopic details of the plate. But you seemed to imply that the same argument would go through for *cosmological* boundaries. To me, this seems like a very different issue. It's not at all clear that one could talk about the microscopic details of the cosmological boundary in the same way. What would you say to a claim that the cosmological boundary is both fundamental and an example of top-down causation?

2) You finesse the question about the "size" of a quantum system by talking about center of mass energies, which I suppose is fine from an operational perspective. But near the end, when you try to dispute that entanglement is an example of top-down causation, you imply that there is such a thing as the "microscopic constituents" of two entangled particles. What do you have in mind here? We've recently had a conversation about this, and how there's often no way to come up with a spacetime representation of the pieces of an entangled state, so there's really no way to assess whether it's "microscopic" or not, living in a higher dimensional configuration space as it does. For example, for a two-qubit state, there are additional parameters (such as the "concurrence", a measure of entanglement) that don't seem to live anywhere at all, or have any size associated with them. So you might need to sharpen up this argument, using your operational language from before, if you don't want to have to defend and define the two "microscopic constituents" of an entangled state. (Or else help me figure out what those constituents might actually be! :-)

Cheers! -Ken

I have a query that concerns randomness and order in Nature. We find lot of logic in the design of universe we happen to belong. How come that all physical processes are governed by randomness rather than any order when one works the probabilty of occurence of the event in our sensors. We tried an experimnet where we mixed in smaller and smaller proportions of regular or ordered events to the normal random events. Our analysis showed that even when moxed regular pulses to a rather miniscular level, chi square test clearly indicated that we have done something not natural or purely random in nature. All this goes to show that we can not affect the Nature and its processes that we try to understand and explain using Physics or sciences in general. Also, i worry if the so-called constants we have designated like strenghts of four force fields/ velocity of light, etc.have changed in magnitude ever since the creation of the Universe billions of years back. Can we design an experiment where we look for an event in the far receeded universe and see if it follows a variation in the value of a physical constant?

May i make a request you and your friends on this site, to kindly visit our essay in the contest and critically examine our contention regarding the role of Consciousness in sciences! Can one talk about human consciousness as well as consciousness of the Universe itself too?

For 1), I meant something like a constraint at the Big Bang, but you'll probably have to slog through my essay to really understand what I'm getting at.

For 2), I don't see how configuration space helps you figure out what the "parts" even are. If there's no basis in which the entangled state separates out into parts, then I don't see how one can talk about parts at all, let alone assign a resolution to them. There is simply no standard answer to the question "how are the parts are entangled?" that doesn't simply list the entire nonlocal entangled state. It gets worse after 2 particles; in principle, if you take QM seriously, there are no "parts" whatsoever -- just a giant entangled structure, and that way lies Many Worlds. Really, one could make the case that GR talks about "smaller structures" than QM and QFT, because GR has a description that separates out into small parts, while QM and QFT don't.

Cheers! -Ken

Dear Sabine,

I thoroughly enjoyed your eloquent essay and agree with much of it. I also look forward to getting and studying your book when it comes out this summer. I wrote a fairly extensive reply to your comments on my essay, arguing that nonlinear dynamics, while in principle not incompatible with reductionism, for all practical purposes obviates it as a fundamental tool. My reply is too lengthy (and not all that relevant) for inclusion here, but you might like to read it.

Again, thanks for your comments and for a very thought-provoking essay.

Best,

Bill

Sabine,

I like your style. Your approach is clear and objective, showing what I consider real modesty about your approach, a healthy attitude that recognizes the need for objectivity in science. Your self-mocking statement concerning free will sets a playful tone that keeps readers interested to the end. Certainly we need to admit the failings of current theory, the inconsistency of dark matter, for example, and your recognition that fundamental depends on current knowledge something I mention about discoveries leading to evolution of that which we consider fundamental. My definition of fundamental is more general, that which is necessary for existence, yours applies to physical theories. And right away you recognize there are other approaches. You use QCD as an underpinning theory; I use ToE, recognizing tools and the coming together of forces to uncover the fundamental - LIGO thinking sensitivities can be enhanced to record the BB and LHC for less than a second after the BB. Hope you can check out my essay, Sabine.

Jim Hoover

Hi Sabine,

1) You do not even give a reference to your earlier writings

in the essay! "No space for details" is no excuse: surely there

was space to briefly present the argument.

2) You did not quote Sean's book in the essay and I just checked: he does not

make the point. Thus my characterization of what you did in the essay

seems to be correct.

maurice

Dear Sabine - I have to apologize, rather embarrassed, because I hadn't realized that you've devoted quite a bit of time to this debate over free will. Having looked now at several of your posts and papers, I think I understand why you care about this issue - because many other people do, and they also feel the need to defend themselves against science. I agree that's very bad.

Still, this debate perpetuates several misconceptions about, for example, reduction and emergence. Karen Crowther has an excellent essay in this contest, and has another paper on "decoupling" these concepts, which are often treated as mutually exclusive. But I question whether they're really useful concepts at all, since probably every case in which one layer of natural order is built on another has unique features. A notion like "phase transition" makes sense - different cases can be usefully compared. What useful comparison can we make between the emergence of chemistry and the emergence of life, or of literature?

If "strong emergence" means that the emergent properties of large systems do not derive from the nature of lower-level systems, there's no good reason to believe in it, and whether or not we can prove it's false, there's plenty of reason to assume it's true. That doesn't mean the behavior of a neural net has to be predictable, even in principle.

But the real question is - what could "free will" possibly mean, that's "undermined" by its dependence on many, many layers of physical and biological systems, not to mention our own language and culture? Clearly I'm the one making choices about what I do, for the most part. Certainly these choices aren't independent of my past, or of the situation in the world around me. Some of these dependencies I'm aware of, others not. Does that mean I'm not the one who's choosing? What does "I" mean, in that case? If it turned out that my consciousness runs on spirit-magic instead of neurons, would that make it more "free"?

So my sense is that the prevalence of a "free will" debate reveals something unsound in our collective mental state, but doesn't help cure it. If only philosophy - which was once such a grand intellectual adventure - could find something helpful to do in the modern world!

May I humbly thank you for your insightful contributions to every other topic you pick up, in your blog.

Conrad

Sorry, I meant to say -- whether or not we can prove strong emergence is false, there's plenty of reason to assume it is.