Some recommended reading
Robert Wald reviews the 2010 book Many Worlds?: Everett, Quantum Theory, and Reality, based on a meeting at Oxford to commemorate the 50th anniversary of Everett's paper.
A central issue in the Everett interpretation is the status of the `Born rule', which asserts that, for state ψ, the probability of obtaining a particular outcome of a measurement is ||Pψ||2, where P is the projection operator onto the eigensubspace associated with the measurement outcome. In traditional interpretations, the Born rule is simply postulated as part of the collapse hypothesis. In the Everett interpretation, it is far from obvious that the Born rule even has any meaning—if all outcomes occur, how can one talk about the probability of a particular outcome? Given the importance of this issue, it is highly appropriate that four chapters of the book (by Saunders, Papineau, Wallace, and Greaves and Myrvold) are devoted to addressing probability and the Born rule from the Everett viewpoint, and three chapters (by Kent, Albert, and Price) are devoted to criticising these views.
See here for my thoughts on this.
The origin of the Everettian heresy (see also Byrne's excellent biography of Everett).
... These efforts gave rise to a lively debate with the Copenhagen group, the existence and content of which have been only recently disclosed by the discovery of unpublished documents. The analysis of such documents opens a window on the conceptual background of Everett’s proposal, and illuminates at the same time some crucial aspects of the Copenhagen view of the measurement problem. Also, it provides an original insight into the interplay between philosophical and social factors which underlay the postwar controversies on the interpretation of quantum mechanics.
... Here is a tentative chronology of the thesis versions and of the related papers:
(1a) Objective vs Subjective probability, short manuscript (first half of 1955).
(1b) Quantitative Measure of Correlation, short manuscript (summer 1955).
(1c) Probability in Wave Mechanics, short manuscript (summer 1955).
(2) Wave Mechanics Without Probability, second version of the dissertation (the long thesis) (winter 1955–1956), published as The Theory of the Universal Wave Function (1973).
(3) On the Foundations of Quantum Mechanics, final dissertation (winter 1956–1957), published as ‘‘Relative State’’ Formulation of Quantum Mechanics (July 1957).
A Commentary on ‘Common SNPs Explain a Large Proportion of the Heritability for Human Height’ by Yang et al. (2010). Why do Visscher and company have to speak so slowly and enunciate so carefully in order to be understood?
During the refereeing process (the paper was rejected by two other journals before publication in Nature Genetics) and following the publication of Yang et al. (2010) it became clear to us that the methodology we applied, the interpretation of the results and the consequences of the findings on the genetic architecture of human height and that for other traits such as complex disease are not well understood or appreciated ...
Turkheimer on heritability: Still Missing.
As a social scientist and twin researcher, I had to struggle with the biological and statistical genetics underlying the Yang et al. analyses, but the analysis of variance, the acausal “capturing” and “tracking” of one domain of variance with another came naturally to me. The situation was reversed for the geneticists who were the target audience of the paper: biologically based scientists, accustomed to genes that have an actual causal pathway to their outcomes. Over and above its technical brilliance, the real contribution of the Yang et al. article is to bring into focus this conceptual chasm between biological and quantitative genetics, and thus between the physical sciences and social science. Genomics is only now learning a hard lesson that social scientists had to learn a long time ago: sometimes prediction is just prediction. That is what the missing heritability problem is really about, and why it has not yet been solved
For more Turkheimer, see here. Note that although he emphasizes the difficulty of teasing out causality in a complex system, for some "engineering" applications (such as genetic engineering), prediction may be enough, as long as the correlations between genetic variant and phenotype are confirmed to be robust across a variety of environments. ;-)
See here for my thoughts on this.
The origin of the Everettian heresy (see also Byrne's excellent biography of Everett).
... These efforts gave rise to a lively debate with the Copenhagen group, the existence and content of which have been only recently disclosed by the discovery of unpublished documents. The analysis of such documents opens a window on the conceptual background of Everett’s proposal, and illuminates at the same time some crucial aspects of the Copenhagen view of the measurement problem. Also, it provides an original insight into the interplay between philosophical and social factors which underlay the postwar controversies on the interpretation of quantum mechanics.
... Here is a tentative chronology of the thesis versions and of the related papers:
(1a) Objective vs Subjective probability, short manuscript (first half of 1955).
(1b) Quantitative Measure of Correlation, short manuscript (summer 1955).
(1c) Probability in Wave Mechanics, short manuscript (summer 1955).
(2) Wave Mechanics Without Probability, second version of the dissertation (the long thesis) (winter 1955–1956), published as The Theory of the Universal Wave Function (1973).
(3) On the Foundations of Quantum Mechanics, final dissertation (winter 1956–1957), published as ‘‘Relative State’’ Formulation of Quantum Mechanics (July 1957).
A Commentary on ‘Common SNPs Explain a Large Proportion of the Heritability for Human Height’ by Yang et al. (2010). Why do Visscher and company have to speak so slowly and enunciate so carefully in order to be understood?
During the refereeing process (the paper was rejected by two other journals before publication in Nature Genetics) and following the publication of Yang et al. (2010) it became clear to us that the methodology we applied, the interpretation of the results and the consequences of the findings on the genetic architecture of human height and that for other traits such as complex disease are not well understood or appreciated ...
Turkheimer on heritability: Still Missing.
As a social scientist and twin researcher, I had to struggle with the biological and statistical genetics underlying the Yang et al. analyses, but the analysis of variance, the acausal “capturing” and “tracking” of one domain of variance with another came naturally to me. The situation was reversed for the geneticists who were the target audience of the paper: biologically based scientists, accustomed to genes that have an actual causal pathway to their outcomes. Over and above its technical brilliance, the real contribution of the Yang et al. article is to bring into focus this conceptual chasm between biological and quantitative genetics, and thus between the physical sciences and social science. Genomics is only now learning a hard lesson that social scientists had to learn a long time ago: sometimes prediction is just prediction. That is what the missing heritability problem is really about, and why it has not yet been solved
For more Turkheimer, see here. Note that although he emphasizes the difficulty of teasing out causality in a complex system, for some "engineering" applications (such as genetic engineering), prediction may be enough, as long as the correlations between genetic variant and phenotype are confirmed to be robust across a variety of environments. ;-)