Quasiparticles and the Miracle of Emergence

http://www.ribbonfarm.com/2015/10/29/quasiparticles-and-the-miracle-of-emergence/

by simulate • 11 years ago

50 16 11 years ago

oofabz• 11 years ago

I wonder if all the things we think of as particles, like electrons and protons, are actually quasiparticles on top of more fundamental mechanics.

simcop2387• 11 years ago

From my limited understanding that's largely how things work out with some (most or all?) string theories. The fundamental mechanics are those of vibrating stings and the particles/quasiparticles are emergent behavior off of the different types of vibrations and different types of strings.

ZeroFries• 11 years ago

According to holon theory, everything that can be considered a "whole" (eg: a particle) emerges from a stack of parts which in turn can be considered wholes which emerge from their own stack of parts. This goes all the way up and all the way down.

Eg: A cell emerges from proteins (among other parts) which emerge from amino-acids, which emerge from molecules, which emerge from atoms, which emerge from particles, which emerge from more fundamental particles, which emerge from probability fields, which emerge from probability fields, etc...

mathgenius2• 11 years ago

This is Laughlin's thesis in his book [1]. The idea is that the mathematics of renormalization as used by the particle physicists, is the same mathematics used to describe quasiparticles. It seems physicists in general have not had much to say in response to this idea.

[1] http://www.physicscentral.com/explore/writers/laughlin.cfm

tfgg• 11 years ago

It seems physicists in general have not had much to say in response to this idea

Huh? My impression is that the notion that the current laws of physics are an effective field theory of some more fundamental theory is pretty widespread and mainstream.

selimthegrim2• 11 years ago

They've had plenty to say. Laughlin's only acolyte is a fellow named Chapline who is known for his unusual theories about black holes. Laughlin has nothing to say about Lorentz invariance.

For a real stab down Laughlin's direction, done 100,000 times better with testable predictions, check out G. Volovik's book "The Universe in a Helium Droplet"

srunni• 11 years ago

Also see: https://en.wikipedia.org/wiki/The_Unreasonable_Effectiveness... (full article: https://www.dartmouth.edu/~matc/MathDrama/reading/Wigner.htm...)

pierrec• 11 years ago

Emergent structures have the property of being possible to generalize about and simulate to some extent by simpler means than the modeling of their most fundamental components. When this is not the case, it means the large scale result of the fundamental components is chaotic.

But if such a chaos were to characterize any given scale of any universe, intelligent life at that scale would be impossible. When the author asks, "How can the same sorts of simple equations keep appearing at every scale of nature that we look for them?", my (perhaps simplistic) answer is that if chaos were to entirely characterize a given scale, that scale would be too remote from ours to be observable. Chaos would be the barrier to observation.

So, I would venture that emergence as we observe it in the universe is not that surprising or miraculous, but inevitable. Though I may be wrong and/or not the first to provide this "explanation".

Retra• 11 years ago

"Emergence" is such a useless word. Everything is emergent. Temperature is the emergent consequence of small-scale particle motions. Orbits are the emergent consequence of particles moving in potential wells. Intelligence is the emergent consequence of neuron chemistry. Traffic is the emergent consequence of driver's goals.

It's especially irritating because people like to say things like this:

"Emergent structures have the property of being possible to generalize about and simulate to some extent by simpler means than the modeling of their most fundamental components. When this is not the case, it means the large scale result of the fundamental components is chaotic."

Our brains require abstractions to function because our brains are subsets of reality. You simply cannot pack all of existence into your brain to conceive the whole thing at once. So everything -- every perceivable phenomenon or relation that exists in any possible experience -- is going to be modeled. This means that there does not exist anything that "when broken into its components" is made of fewer abstract components than the whole. That's contradictory nonsense.

Which means you can't assume that "when it happens," you'll get a chaotic universe (or whatever you meant by that.) It's got nothing to do with scale, since choosing to call one thing 'fundamental' and another an 'emergent whole' is no less of an abstraction that swapping them around. You could just as easily say the motion of particles is an emergent property of the temperature of the whole, and you'd be no less wrong about it. It's a dualistic relation.

Which makes "emergence" a pointless concept. There is no "absolute simple" for you to take as a fundamental abstraction from which other things emerge. And I'm pretty sure the concept has never actually been used to solve a single problem. Not even hypothetically.

powertower• 11 years ago

You can consider a "lack of an electron" as the same thing as an "Electron hole quasiparticle".

The problem is this only holds 100% true in the abstract thought and specific mathematical frameworks (and their formulas) you are working in.

While you can do the math, and get the right results, it does not necessarily make it real outside of the human brain.

The majority of quasiparticles are just another way of looking at things. Some are totally human creations, others are combined effects, and some emergent phenomena.

gradys• 11 years ago

While you can do the math, and get the right results, it does not necessarily make it real outside of the human brain.

Following this same logic, nothing is necessarily real outside of the human brain.

No experiment you can do, including simply observing human-scale events with your eyes, necessarily tells you anything about the "real" world. Everything that has ever been done in science amounts to doing the math and getting the right results.

This is a rift in the philosophy of science: is science telling us real things about the real world, or is it just producing models that happen to fit data generated from experiments?

I take the latter position, but rather than concluding from this that I should no longer use the term "the real world", I find it more useful to simply redefine "the real world" to be the set of models that are consistent with data generated from experiments. This means that if multiple models that explain the same phenomenon are all consistent with the data, all of the models are equally "real".

baq• 11 years ago

one interesting related question is "is math real?" does math exist without human brain? i mean there's a reason why mathematicians prefer the word 'discover' instead of 'invent', but can something that theoretically could exist without a universe to belong in be real? there's a lot of interesting reading at https://en.wikipedia.org/wiki/Philosophy_of_mathematics if you've got time to spare.

lambdapie• 11 years ago

When high level behavior that can be described by simple equations emerges from low level laws, we call it physics. When it doesn't, we call it chemistry, biology, geology, etc. (EDIT: how could I forget econoimics :-))

There is only one thing which is more unreasonable than the unreasonable effectiveness of mathematics in physics, and this is the unreasonable ineffectiveness of mathematics in biology.

— Israel Gelfand

selimthegrim2• 11 years ago

Quasiparticles and the Miracle of Emergence

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