✎ Emergence [The Physics Travel Guide]

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====== Emergence ======

<blockquote>I tend to assume that space-time and everything in it are in some sense emergent <cite>[[https://www.quantamagazine.org/edward-witten-ponders-the-nature-of-reality-20171128/|Ed Witten]]</cite></blockquote>

<blockquote>Symmetries are caused by things, not the cause of things <cite>p. 124 in "A different Universe" by R. Laughlin</cite></blockquote>

Laughlin's book is about a lot of things - it touches on many subjects. But mostly, it is about the problems with reductionism and about the age of emergence (collective phenomena) which he champions. He contends that physics - and though he alludes to it, I don't think he comes out and says it completely so I will: all of 'science' - has been entirely focused on taking things apart - breaking them down into their most primitive constituents in an effort to understand and control them. In physics we see this in string theory for example - the constant quest for a 'theory of everything'. He contrasts this with the organizational properties of 'massive objects' (such as proteins and semi-conductors) and demonstrates that understanding the parts doesn't provide understanding of the 'wholes' - and in many cases, the 'whole' constructs provide detailed accuracy of things like scientific constants that flabbergast scientists when they discover them.

A case in point has to do with Laughlin's work with the Hall effect (which has to do with what happens when a magnet is placed next to a current flow.) Laughlin's Nobel work was related to a discovery that Klaus von Klitzing made involving low temperature semiconductors and the Hall effect - in field effect transistors at low temperature the Hall resistance becomes quantum mechanical and is revealed in 'quantum' stairsteps. Von Klitzing's insight was that these quantum staristeps were a combination of fundamental constants: the quantum of electric charge e, Planck's constant h, and the speed of light c - all of which we think of as the fundamental building blocks of the universe. Here's what Laughlin has to say about this:

//This fact has the obvious implication that you can measure the building blocks with breathtaking accuracy without dealing with the building blocks directly. This is deeply important and deeply upsetting to most physicists. The more thoughtful of them find it impossible to believe until they study the numbers, end even then suspect something to be amiss. But nothing ever is... The impact this discovery had on physics would be hard to overstate. I remember the day my colleague Dan Tsui brought the von Klitzing paper and ... urged everyone to thing about where this astonishing accuracy could have come from. No one had an explanation. We all knew that von Klitzing's samples were imperfect... These [imperfections] are known to influence other electrical measurements... But this explanation turned out to be wrong. As a result of theoretical work done after the fact, including some of my own, we now understand that imperfection has actually the opposite effect, namely to cause the perfection of the measurement - a dramatic reversal worthy of the finest Greek drama. The quantum Hall effect is, in fact, a magnificent example of perfection emerging out of imperfection... Collective phenomena are both common in nature and central to modern physical science, so the effect is in this sense neither unprecedented nor hard to understand. However, the extreme accuracy of the von Klitzing effect makes its collective nature undeniable, and therein lies its special significance.//

He goes on to say that this discovery was a watershed event in science - in which physical science stepped out of reductionism into the age of emergence. Laughlin and his colleagues went on to show that there are even quantized steps within the Hall effect which divide the fundamental electrical charge e into thirds and thus "proved the existence of new phases of matter in which the elementary excitations - the particles - carried an exact fraction of e." A further demonstration of emergence.

<cite>http://pullonsupermanscape.typepad.com/pull_on_supermans_cape/celestial/ and "A Different Universe" - by Laughlin</cite>
</blockquote>

<blockquote>the concept of togetherness has suffered in the sciences, and
especially, in physics, where all of the effort has been on describing the individual,
typically by breaking its description down to that of even smaller
individuals. While, without any doubt, this has been a useful endeavour,
it unfortunately has evolved in a rigid doctrine, leaving no space for anything
else. The most extreme manifestation of this dogma is the use of the
term ‘theory of everything’ in particle physics. We will provide an alternative
conceptual template for a theory of everything, supported not only by
scientific examples, but also by everyday ones.
Biology evolved from chopping up individual animals in laboratories, to
considering them in the context of other other animals and varying environments.
the result is the theory of evolution of species. Similarly, our
current (still very poor) understanding of the human brain makes it clear
that the human brain should not be studied as something in isolation, but
as something that fundamentally requires interaction with other brains [30].
In contemporary audio equipment, music consists of nothing but a strings
of zeros and ones. Instead, the entities that truly make up music are pitch,
sound, rhythm, chord progression, crescendo, and so on. And in particular,
music is not just a bag of these, since their intricate interaction is even
more important than these constituents themselves. The same is true for
film, where it isn’t even that clear what it is made up from, but it does
include such things as (easily replaceable) actors, decors, cameras, which all
are part of a soup stirred by a director. But again, in contemporary video
equipment, it is nothing but a string of zeros and ones.
In fact, everything that goes on in pretty much all modern devices is
nothing but zeros and ones. While it was Turing’s brilliance to realise that
this could in fact be done, and provided a foundation for the theory of
computability [38], this is in fact the only place where the zeros and ones are
truly meaningful, in the form of a Turing machine. Elsewhere, it is nothing
but a (universal) representation, with no conceptual qualities regarding the subject matter.
<cite>https://arxiv.org/abs/1602.07618</cite>
</blockquote>

<blockquote>
A much less controversial case of emergence of vacuum properties is the special relationship seen between the forces of electricity and nuclear decay on the one hand, and the masses of two special elementary particles, called W and Z bosons, on the other.lo The physical idea behind this relationship is that a superconducting fluid-more precisely, a multicomponent abstraction of such a fluid-pervades the universe and modi es the electric force to create the weak nuclear force, somewhat as a laboratory superconductor modi es electric forces. This fluid also has sloshing motions, which, like sound in a solid, are quantized and thus show up experimentally as particles.llThe corresponding sloshing motion o f the superconductor, called a plasmon, is seen routinely in electron microscope experiments.12 Not only are the W and Z bosons observed to exist, but their slight mass difference is exactly the value required by the observed differences between the nuclear and electric force strengths. Whether such a uid really exists is still somewhat controversial because the Higgs particle, a more sophisticated sloshing motion of the uid, has not yet been observed. The reason is almost certainly the technical limitations of existing accelerators, and most physicists expect the Higgs particle to be found soon.

Many other aspects ofthe vacuum look suspiciously emergent. There is, for example, the great simplicity of its quantum-field-theoretic description, which is unusual because such descriptions in ordinary matter tend to be complicated except when they emerge-as they do in superconductor or superfluid. There is also the hierarchy of scales, the tendency of phenomena at progressively longer lengths and times to be sequentially subordinate.

<cite>"A different Universe" by Robert Laughlin</cite>
</blockquote>

----

**Recommended Articles:**

* A great explanation of emergence for laymen is [[https://www.ribbonfarm.com/2015/10/29/quasiparticles-and-the-miracle-of-emergence/|Quasiparticles and the Miracle of Emergence]] by Brian Skinner

**Recommended Books**

* "A different Universe" by Robert Laughlin
  * "The devil in the details" by Battermann
<tabbox Student>

<blockquote>”we call emergent behavior . . . the phenomena that owe their
existence to interactions between many subunits, but whose existence cannot be deduced
from a detailed knowledge of those subunits alone”

<cite> D. L. Cox and D. Pines. Complex Adaptive Matter: Emergent Phenomena in Materials. MRS Bulletin. 30, 425 (2005).  </cite></blockquote>

Most important Essays:

*  ”More is Different”  P. W. Anderson
  * "The Theory of Everything" by Laughlin and Pines

See also

* https://www.perimeterinstitute.ca/videos/emergent-gauge-fields-and-their-condensation-quantum-spin-liquids
<tabbox Researcher> 
<blockquote>
Despite all this evidence that the reductionist paradigm in physics is in trouble, subnuclear experiments are still generally described in reductionist terms. This is especially curious considering that much of the thinking built into the standard model reflects the idea that the vacuum is a phase and that the laws of physics are reasonably simple and straightforward at the nuclear scale-but not beyond-because they are universal properties of that phase. Nonetheless, instead of low-energy universality, physicists speak of e ective eld theory. Instead of phases, we speak of symmetry-breaking. Instead of phase transitions, the unification of forces. The situation reminds me of a hospital where no one ever dies but instead experiences "negative patient care outcome" or "failure to achieve wellness potential."14 In either case the confusion is ideological. The death of a patient is an unthinkable failure of the hospital's mission to preserve life. The subordination of understanding to principles of phase organization is a similarly unthinkable failure of one's mission to master the universe with mathematics. In situations that matter, mythologies are important powerful things, and sometimes we humans go to enormous lengths to see the world as we think it should be, even when the evidence says we are mistaken.

<cite>pp. 113-114 IN A different Universe, by R. Laughlin </cite></blockquote>

*  [[http://agenda.albanova.se/conferenceDisplay.py?confId=575|Emergent Phenomena in Condensed Matter and Particle Physics]] by Witten
  * [[https://arxiv.org/abs/1710.01791|Symmetry and Emergence]] by Edward Witten
  * [[https://arxiv.org/abs/0707.4568|Emergent Quantum Mechanics and Emergent Symmetries]] by Gerard 't Hooft
  * [[https://www.youtube.com/watch?v=XM4rsPnlZyg|Duality and emergent gauge symmetry]] by Nathan Seiberg
  * [[https://arxiv.org/abs/0711.0273|The Emergence of Spacetime, or, Quantum Gravity on Your Desktop]] by R. Loll and also "[[https://www.researchgate.net/file.PostFileLoader.html?id=53156f63d039b1f0128b45c6&assetKey=AS%3A272469355630607%401441973164908|The self-organizing quantum universe]]" by J Ambjørn et. al.
  * DYNAMICAL STABILITY OF LOCAL GAUGE SYMMETRY by D. FOERSTER
  * [[http://iopscience.iop.org/article/10.1088/1742-6596/361/1/012002/pdf|Quantum Theory as an Emergent Phenomenon: Foundations and Phenomenology]] by Stephen L. Adler. (A draft of his book on this topic, can be found here: https://arxiv.org/abs/hep-th/0206120)
  * [[https://arxiv.org/abs/0805.2156|Causality as an emergent macroscopic phenomenon: The Lee-Wick O(N) model]] by Benjamin Grinstein, Donal O'Connell, Mark B. Wise
  * See http://dao.mit.edu/~wen/pub/cosmos.html for papers how gauge symmetries can emerge.
  * [[https://arxiv.org/abs/0809.0151|More Really is Different]] by Mile Gu et. al. 
  
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