Emergence is a popular hot topic word these days, and has been offered by @Markus Hanke in another thread in relation to gravity.

So the question arises "Can the Genie be put back in the bottle ?"

Or is emergence reversible or irreversible or even irrelevant as one Physicist has written a book he believes to show ?

Note this choice is non binary and cannot be addressed by classical logic alone.

Physics Fixes Everything

This reveals something surprising: the term emergence is redundant. In its weak form it is so weak that it applies to everything.  In its strong form it is so restrictive that it is like the belief that there are pixies in your garden, impossible to exclude but not worth spending your time on.  Emergence either applies to all systems or to none.  Rather than telling us something about the nature of the world, it is an illusion, an artefact of our cognitive limitations. 

My list of choices is always irreversible / sometimes irreversible / never irreversible but I will add irrelevant out of deference.

Obviously your answer has implications for gravity and many other phenomena.

8 minutes ago, studiot said:

Emergence is a popular hot topic word these days, and has been offered by @Markus Hanke in another thread in relation to gravity.

So the question arises "Can the Genie be put back in the bottle ?"

Or is emergence reversible or irreversible or even irrelevant as one Physicist has written a book he believes to show ?

Note this choice is non binary and cannot be addressed by classical logic alone.

My list of choices is always irreversible / sometimes irreversible / never irreversible but I will add irrelevant out of deference.

Obviously your answer has implications for gravity and many other phenomena.

I may be being thick but I don’t understand what is meant in this context by putting the genie back in the bottle. Surely an emergent property is just the consequence, at larger scales, of a sufficiently large aggregate of entities at a smaller scale? Things like the bulk properties of a liquid being due to the aggregate behaviour of large assemblies of constituent molecules.

I suppose you can get rid of (“reverse”) the emergent phenomenon by disaggregating them, but that seems a bit obvious. Can you expand a bit?

I thought emergence was the other way around: You can't predict the result, you can only afterwards say "A leads to B by observing what B is.

I would venture there are differing types of 'emergence'.
The one type that immediately comes to mind is Thermodynamics and fluid flow emerging from particle statistics, which is essentially observer scale dependence.
The 'genie' is never let out of the bottle, we are just investigating a different scale, so no need to put the 'genie' back in.

I can also envisage an emergent property that arises from interactions of some other properties, such that the original interacting properties are no longer available for investigation, and this, irreversible.
I can't think of one such emergence off the top of my head, and I don't currently have time to research one, as I have to attend the wedding of the son of a deceased close friend, but this seems like an interesting topic, so I had to quickly post.

Well, three different posts with three different views of 'emergent'.

Exactly as @MigL predicts.

I think the reversibility issue is a very big deal indeed, since if the paper Markus referred to is correct that gravity is emergent, and if you can reverse the its emergence you could reverse or negate gravity.

I note no one has addressed the proposals put forward in the passage I quoted.

1 hour ago, StringJunky said:

I thought emergence was the other way around: You can't predict the result, you can only afterwards say "A leads to B by observing what B is.

2 hours ago, exchemist said:

I may be being thick but I don’t understand what is meant in this context by putting the genie back in the bottle. Surely an emergent property is just the consequence, at larger scales, of a sufficiently large aggregate of entities at a smaller scale? Things like the bulk properties of a liquid being due to the aggregate behaviour of large assemblies of constituent molecules.

I suppose you can get rid of (“reverse”) the emergent phenomenon by disaggregating them, but that seems a bit obvious. Can you expand a bit?

My understanding of emergence is somewhere between exchemist's aggregate description and that of StringJunky.

I agree the emergent phenomenon is sometimes surprising but I don't agree that it is never calculable or predictable.

I have to confess my answer to the question, at least at the moment is sometimes reversible.

Perhaps some examples (all welcome here) might help clarify matters.

1) If a bake a sponge cake is the result of the baking unpredictable ?

It is irreversible.

Is is emergent ?

2) If I take a pile of bricks or blocks and arrange them in a certain way a structure emerges which has the additional property of spanning gaps and supporting loads moving across that gap.

That is how arch bridges are built. This property only becomes extant when the last block is placed.

If I place the blocks in any other configuration the property does not emerge.

However it is reversible.

I could dismantle the arrangement and even re erect it somewhere else, as many times as I wish.

And so long as I kept to the correct configuration the spanning and load bearing property would reemerge each time.

So is emergence a one time, one shot phenomenon ?

Or must it repeat every time the correct configuration occurs ?

Many thanks for the thoughts and replies so far.

2 hours ago, studiot said:

Well, three different posts with three different views of 'emergent'.

Exactly as @MigL predicts.

I think the reversibility issue is a very big deal indeed, since if the paper Markus referred to is correct that gravity is emergent, and if you can reverse the its emergence you could reverse or negate gravity.

I note no one has addressed the proposals put forward in the passage I quoted.

My understanding of emergence is somewhere between exchemist's aggregate description and that of StringJunky.

I agree the emergent phenomenon is sometimes surprising but I don't agree that it is never calculable or predictable.

I have to confess my answer to the question, at least at the moment is sometimes reversible.

Perhaps some examples (all welcome here) might help clarify matters.

1) If a bake a sponge cake is the result of the baking unpredictable ?

It is irreversible.

Is is emergent ?

2) If I take a pile of bricks or blocks and arrange them in a certain way a structure emerges which has the additional property of spanning gaps and supporting loads moving across that gap.

That is how arch bridges are built. This property only becomes extant when the last block is placed.

If I place the blocks in any other configuration the property does not emerge.

However it is reversible.

I could dismantle the arrangement and even re erect it somewhere else, as many times as I wish.

And so long as I kept to the correct configuration the spanning and load bearing property would reemerge each time.

So is emergence a one time, one shot phenomenon ?

Or must it repeat every time the correct configuration occurs ?

Many thanks for the thoughts and replies so far.

Well in the examples that spring to my mind at least, emergent properties most certainly can be derived from the behaviour of the small scale entities responsible. That is what statistical thermodynamics is all about, surely? Macroscopic properties of bulk matter are derived, quantitatively, from the statistical behaviour of molecules.

10 hours ago, studiot said:

Emergence is a popular hot topic word these days, and has been offered by @Markus Hanke in another thread in relation to gravity.

An important topic indeed I would just like to add here that “emergent gravity” is a term from existent literature, I merely used it since it seems to fit with the research program in question.

10 hours ago, studiot said:

Emergence either applies to all systems or to none.

I don’t agree with this. For example, one wouldn’t expect to see emergence in a simple harmonic oscillator; but if you had eg a very large ensemble of double pendulums all somehow influencing one another, it might be a different story. I think the complexity of the systems plays a role, and perhaps also the types of dynamics within it (linear? Non-linear? Chaotic?). Of course these terms need to be made precise.

5 hours ago, exchemist said:

Well in the examples that spring to my mind at least, emergent properties most certainly can be derived from the behaviour of the small scale entities responsible.

I think we must carefully distinguish weak from strong emergence here. There are no known examples of strong emergence, but plenty of examples of weak emergence - also gravity would fall into this latter category.

6 hours ago, Markus Hanke said:

16 hours ago, studiot said:

Emergence either applies to all systems or to none.

I don’t agree with this. For example, one wouldn’t expect to see emergence in a simple harmonic oscillator; but if you had eg a very large ensemble of double pendulums all somehow influencing one another, it might be a different story. I think the complexity of the systems plays a role, and perhaps also the types of dynamics within it (linear? Non-linear? Chaotic?). Of course these terms need to be made precise.

My apologies, I didn't make it properly clear, that this was a quote from a brand new book "Physics Fixes Everything"

I do not support this view, but I thought it should be included as the trend seemed to be moving this way.

6 hours ago, Markus Hanke said:

I think we must carefully distinguish weak from strong emergence here. There are no known examples of strong emergence, but plenty of examples of weak emergence - also gravity would fall into this latter category.

In fact classifying notions into weak and strong versions also seems to be gaining popularity, another trend I do not support.

If I were to classify emergence I would tend towards static emergence v dynamic emergence, a well trodden classification.

To my mind emergence is something that occurs reliably and repeatedly in a system only in certain specialised circumstances as opposed to the many other circumstances that can and do pertain for that system.

10 minutes ago, studiot said:

If I were to classify emergence I would tend towards static emergence v dynamic emergence, a well trodden classification.

I must admit I haven’t heard of this. Could you briefly explain the basic distinction here?

4 minutes ago, Markus Hanke said:

I must admit I haven’t heard of this. Could you briefly explain the basic distinction here?

My example of the arch bridge would be an example of static emergence.

A possible example of dynamic emergence might be the maths schoolmaster's favourite surprise.
"The contact point with the ground in a rolling wheel is not moving since it has a forward velocity as part of the system exactly equal and opposite to its backward velocity by virtue of its rotation."

My trying to be too brief again.
I meant that I was applying tried and tested classifications static and dynamic to emergence, not that such application is well trodden.

Complex systems, such as those of exchemist, would be of the dynamic type.

In a way the emergent property is a result of dynamic equilibrium of constant change.

Edited Sunday at 10:27 AM2 days by studiot

13 hours ago, exchemist said:

Well in the examples that spring to my mind at least, emergent properties most certainly can be derived from the behaviour of the small scale entities responsible. That is what statistical thermodynamics is all about, surely? Macroscopic properties of bulk matter are derived, quantitatively, from the statistical behaviour of molecules.

.... where the number of components/participants tends towards infinity. I have read. Like how many water molecules to make the liquid we know?

Edited Sunday at 11:47 AM2 days by StringJunky

18 hours ago, MigL said:

I can also envisage an emergent property that arises from interactions of some other properties, such that the original interacting properties are no longer available for investigation, and this, irreversible.
I can't think of one such emergence off the top of my head, and I don't currently have time to research one

Mass is an emergent property of leptons, quarks and W/Z bosons that arises from an interaction ( Higgs mechanism ) where the original interactors are no longer available. If Gravity was part of the original GUT SuperForce ( ToE ), it would have similarly emerged through a previous symmetry break, albeit a different emergence than the one suspected by @Markus Hanke .
This seems very different ( to me ) from the statistical emergence of Thermodynamics or the 'ganged' behavior of harmonic oscillators.

Whether you choose to call the difference reversible vs irreversible, or weak vs strong emergence, the difference is evident.

Our very definition of 'emergence' needs clarification.
I mean, statistical, grouped or ganged, behavior does lead to differing properties of the system because of non-linear or chaotic factors, but we can also investigate the behavior of the individual components of that system, by simply changing scales, to gain some idea of how they contribute to the system's behavior.

On 7/26/2026 at 4:39 AM, Markus Hanke said:

An important topic indeed I would just like to add here that “emergent gravity” is a term from existent literature, I merely used it since it seems to fit with the research program in question.

I don’t agree with this. For example, one wouldn’t expect to see emergence in a simple harmonic oscillator; but if you had eg a very large ensemble of double pendulums all somehow influencing one another, it might be a different story. I think the complexity of the systems plays a role, and perhaps also the types of dynamics within it (linear? Non-linear? Chaotic?). Of course these terms need to be made precise.

I think we must carefully distinguish weak from strong emergence here. There are no known examples of strong emergence, but plenty of examples of weak emergence - also gravity would fall into this latter category.

If there are no known examples, in what sense is strong emergence a real phenomenon?

2 hours ago, exchemist said:

If there are no known examples, in what sense is strong emergence a real phenomenon?

It seems more a philosophical conjecture than anything else.

In strong emergence higher-level properties of a system arise from lower-level parts, but cannot be deduced, predicted, or reduced to those parts even in principle. That's the standard criterion for "strong." It posits that there are irreducible traits and potential downward causation (our old friend from all those consciousness threads).

There's also the novelty aspect: a strongly emergent property introduces a genuinely new quality or dimension of reality that does not exist in the individual components (again, hello Hard Problem of Consciousness and that whole rabbit hole).

Is there a macro-level whole which exerts a causal effect back down on its micro-level constituent parts? I guess for some the whole strong emergence conjecture gets traction when some phenomenon seems to resolutely defy a complete bottom-up explanation and then requires new fundamental laws or concepts operating at a more holistic domain.

Anyone?

Edited yesterday at 08:21 PM1 day by TheVat

9 minutes ago, TheVat said:

It seems more a philosophical conjecture than anything else.

In strong emergence higher-level properties of a system arise from lower-level parts, but cannot be deduced, predicted, or reduced to those parts even in principle. That's the standard criterion for "strong." It posits that there are irreducible traits and potential downward causation (our old friend from all those consciousness threads).

There's also the novelty aspect: a strongly emergent property introduces a genuinely new quality or dimension of reality that does not exist in the individual components (again, hello Hard Problem of Consciousness and that whole rabbit hole).

Is there a macro-level whole which exerts a causal effect back down on its micro-level constituent parts? I guess for some the whole strong emergence conjecture gets traction when some phenomenon seems to resolutely defy a complete bottom-up explanation and then requires new fundamental laws or concepts operating at a more holistic domain.

Anyone?

Hmm, itchy beard time, then. 😉

3 minutes ago, exchemist said:

Hmm, itchy beard time, then. 😉

Haha, yes. David Bohm is maybe the poster child for strong emergence, attempting to take all the mysteries and roll them together. His implicate order does make for some entertaining reading, as he flips strong emergence on its ear and suggests what looks like emergence is actually the unfolding of an underlying, primary reality. Scratch away!

1 hour ago, TheVat said:

There's also the novelty aspect: a strongly emergent property introduces a genuinely new quality or dimension of reality that does not exist in the individual components

In other words, a pin to the bubble of Naturalism, Realism, Causal Closure, & the Principle of Sufficient Reason

So no biggie then.

1 hour ago, TheVat said:

Haha, yes. David Bohm is maybe the poster child for strong emergence, attempting to take all the mysteries and roll them together. His implicate order does make for some entertaining reading, as he flips strong emergence on its ear and suggests what looks like emergence is actually the unfolding of an underlying, primary reality. Scratch away!

This was one of Write4U’s obsessions on the other forum. it isn’t science, though. Whereas weak emergence is.

17 hours ago, sethoflagos said:

In other words, a pin to the bubble of Naturalism, Realism, Causal Closure, & the Principle of Sufficient Reason

So no biggie then.

Yep, at the end of the day we're all methodological naturalists.

17 hours ago, exchemist said:

This was one of Write4U’s obsessions on the other forum. it isn’t science, though. Whereas weak emergence is.

Yep, science remains reductionist because it works. Though I guess there have been rumblings from condensed matter physicists that high temp superconductivity might provide something like strong emergence. Not my field, so I have no idea how compelling their case is.

ETA: apparently, in condensed matter physics, it's something called strong correlation which is seen as a type of strong emergence.

https://cmsa.fas.harvard.edu/event/strongly-correlated-quantum-materials-and-high-temperature-superconductors-series/

29 minutes ago, TheVat said:

Yep, at the end of the day we're all methodological naturalists.

Question:

If we lacked today's understanding of chemistry, might we not view fire as a strongly emergent property of large heaps of dried organic matter and air? We could see it initiated by a tiny spark of incandesence from a flint only to spawn this monster that seemed to 'magically' generate its own downwardly causative, self-sustaining incandescence that clearly was present in neither the heaps nor the air prior to ignition.

Strong emergence has also been invoked in sudden generation of improved technologies during periods of economic growth.

Perhaps even dark energy is strongly emergent (if there is such an animal) as it does apparently seem to appear literally out of nowhere to influence the remainder of the universe.

I don't actually think these will prove to be valid examples. But one thought that occurs to me that all three exhibit the exponential growth I associate with positive feedback systems. Need to think about it a bit more, but is this a characteristic of over-determined systems - those with too many 'causes' for the existing 'effects'?

8 minutes ago, sethoflagos said:

we lacked today's understanding of chemistry, might we not view fire as a strongly emergent property of large heaps of dried organic matter and air? We could see it initiated by a tiny spark of incandesence from a flint only to spawn this monster that seemed to 'magically' generate its own downwardly causative, self-sustaining incandescence that clearly was present in neither the heaps nor the air prior to ignition.

Cool example. And so as our knowledge of oxidation grows, we find that the macro-level "monster," becomes an instance of overdetermination and thus a redundant thing which is scientifically absurd.

Perhaps consciousness, as seen in the "downward causation" theorizing could suffer the same fate as the ancient's fire demon? The macro-property just becomes a redundant cause alongside the micro-properties in the firing neurons and so on....so the macro-effect is then considered overdetermined. The macro-property, fire monster or thinking of the color orange is stripped of its causal power, collapsing into...uh oh...epiphenomenalism.

26 minutes ago, TheVat said:

epiphenomenalism

Bet you can't get that one past Emily!

Don't tempt me! LoL.