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.