Anderson's 1972 More is Different

Latest revision as of 15:06, 18 September 2008

He is making the argument for the non triviality of the sciences in courser levels than physics. He invokes the idea of symmetry breaking.

I'm not entirely clear yet what is meant by symmetry breaking. Is a system symmetrical if it can be in all possible states, or perhaps if it spends equal amount of time in every possible state?

" In the absence of anything more complicated than a collection of free molecules, the symmetry laws are never broken, on average. We need living matter to produce an actual unsymmetry in the populations. "

"By symmetry we means the existence of different viewpoints from which the system appears the same" I think he is using a very loose and abstract sense of 'viewpoint'

It is hard for me to get around what he means by symmetry and broken symmetries. he seems to be using it in many different senses and is also switching scales freely.

"Temporal regularity is a means of handling information, similar to information-bearing spatial regularity."

The idea of symmetry seems to be tied up in the idea of objects having interactions. Presumable, a collection of non interacting atoms will not display any broken symmetries. A crystal involves particles restricting each other's states. This account makes sense of the quote that talks about symmetry breaking involving rigidity. It seems that high symmetry corresponds to many states, but that connection doesn't concretize anything for me.

And finally we get to 'complication' where increasing complication corresponds to fewer symmetries. 'going up in the heirarchy' corresponds to increasing complication. This involves TBD meanings for 'complication', 'heirarchy' and, more nit pickingly, 'going up'

"The relationship between a system and its parts is intellectually a one way street" Huh?

This paper is difficult to reconcile with the Fodor. Fodor's way out of extreme extensions of reductionism is the type-token distinction. Anderson is also paving a way out of the extreme claims of reduction, but is there a sense in which both their accounts are the same? Well, type token is saying that there is something that all experiences of pain have in common, even though each instance of pain is totally physically different. Anderson's symmetry's are patterns that can be abstracted out of the physical details. Perhaps there is a connection.

I'll have to reread this later in the week

Yes, I will.

Ok, second reading. Here is an important quote: "The crystal very suddenly and unpredicatbly displays an entirely new and very beautiful symmetry" I think that here he is using the non techincal definiation of symmetry. "symmetrical as it is, a crystal is less symetrical than perfect homogeniety" That is confusing, it gets into scale because perfect homogeniety is an approximation. Unless I don't yet have the sense of symmetry that he is providing.

He does eventually distinguish between repealing, violating and breaking symmetry

He hints at the emergence of periodicity at scales where it is exhibited. I expect I will have a perspective on that by the end of the semester, from dynamical systems. How would i phrase this in terms of broken symmetrys? The symmetry of the continuity of time is broken.