Saturday, July 25, 2015

The nanoscale: The edge of emergence

One of the most profound concepts to come out of condensed matter physics is the idea of emergent properties - nontrivial properties of a system that are not trivially deducible from the microscopic aspects and interactions of the underlying degrees of freedom, and that become even better defined as the system size grows.  One example is the rigidity of solids:  A single carbon atom is not rigid; a small cluster of carbon atoms has a countable number of discrete vibrational modes; but a large number of carbon atoms coupled by sp3 bonds becomes a diamond, one of the hardest, most mechanically rigid solids there is, so stiff that compressive sound travels at 12 km/s, 35 times faster than in air.  Somehow, going from one atom to many, the concept of rigidity acquires meaning, and the speed of sound in diamond approaches a precise value.   

This idea, that something remarkable, exact, yet not at all obvious can emerge collectively and even generically, is why condensed matter physics is profound and not just "mopping up the details".  This is the heart of Bob Laughlin's first book, A Different Universe:  Reinventing Physics from the Bottom Down, and was articulated concisely by Laughlin and Pines in their "Theory of Everything" paper.  

I was recently rereading that book, and one chapter articulates Laughlin's basically dismissive take on nanoscience.  He refers to it as a "carnival of baubles" - his view is that otherwise smart people get sucked into playing around at the nanoscale because it's diverting and involves fun, cool toys (i.e., everything looks cool under an electron microscope!), instead of spending their time and effort actually trying to think about deep, fundamental questions.   Well, everyone is entitled to their opinion, but it won't surprise you that I disagree with much of that take.  Working at the nanoscale allows us to examine how emergence works in specific cases, sets the ground work for the materials and devices of future technologies (two topics I touch on in my book), and allows us to develop new probes and techniques precisely for asking (some subset of) deep questions.   Like being able to probe matter on ultrafast timescales, or over a huge temperature range, or in systems of unprecedented purity, pushing our control and manipulation of materials to the nano regime lets us ask new and different questions, and that's how we make progress and find surprises.  This isn't an infatuation with baubles (though everything does look cool under an electron microscope).  


DanM said...

You need to start sounding more like a curmudgeon if you want to win a Nobel Prize.

Douglas Natelson said...

I'll add that to the long, long list of things I need to do to be in line for a Nobel, Dan.

Anonymous said...

I find the title of this post a bit debatable; nanoscale (condensed) matter is not the edge of emergence - if with "the edge" you mean "the first edge", as in "at each scale new properties emerge". This does not happen first at the nanoscale. One can arguably make the case that the properties of an atom are emergent themselves.
Hence, the nanoscale would not be the (first) edge of emergence.

I do fully agree though with what you write in your post, and especially that "Working at the nanoscale allows us to examine how emergence works in specific cases."

Anonymous said...

It's ironic that Laughlin should claim that, given that the quantum Hall effect (and, indeed, the fractional version) was discovered by folks playing with such nanobaubles.

Anonymous said...

Laughlin is a nut (Inertial confinement fusion and civil engineering on the ocean floor, and fission waste doesn't matter? , c'mon is this guy serious?).

He's much to kind regarding nanotechnology.

Nanotechnology is completely useless.

Steve W said...

I guess it is worth noting that Laughlin's comments are now at least ten years old, and nanotechnology research has likely matured since then. However, I find the critique very true of SOME groups, especially at that time, and especially on the side of "nanochemistry". It always seems that science goes through certain trends where research in an area explodes, and only at the end of the initial burst do the useful aspects start to emerge. Everything is stamp collecting before that.