[extropy-chat] the many worlds of Hugh Everett, III

scerir scerir at libero.it
Tue Oct 24 08:51:27 UTC 2006

Damien Broderick:
> [...] why he (H.Everett) didn't significantly develop
> relative state theory in the 25 years--half his
> life--after publishing it.

The 1970 Varenna summer course (on the Como lake) was
dedicated to the 'Foundations of Quantum Mechanics' (not 
an interesting subject, at that time!), following 
a suggestion from Franco Selleri (marxian-realist 
physicist). It had 84 participants, and its 
proceedings (editor B.d'Espagnat, 1971) reveals 
a diversified spectrum of subjects (such as measurement, 
hidden variables, non-locality, interpretations) and 
people (Wigner, Jauch, Shimony, d'Espagnat, Bell, 
de Broglie, Selleri, Bohm, de Witt I suppose, etc.),
and philosophies. 

It is perhaps correct to say that, untill then, the
Everett's 'relative state' interpretation (which is 
different from the modern 'many worlds' interpretation)
was largely unknown, at least in Europe.

Leaving aside technical problems (like the memory
capacity of the observer in the 'relative state'
interpretation, or the normalization of probabilities
within the 'branching', or the conservation of
energy and the formation of 'many worlds', etc.) 
the difficult problem, with Everett's interpretation,
was its 'ontology'. 

Because it was a 'realistic' interpretation [1] in which 
the states are physical states and not just available 
informations about the preparation of quantum systems 
(like in the orthodox interpretation).

I think the above has something to do with your question, 
and with Everett's story.


[1] Not easy to define realism, in general quoting
E.P.R. is a must here "if, without in any way disturbing 
a system, we can predict with certainty (i.e. with 
probability equal to unity) the value of a physical quantity, 
then there exists an element of physical reality 
corresponding to this physical quantity." 

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