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From: <hal.domain.name.hidden>

Date: Thu, 29 Apr 1999 14:43:41 -0700

This is from http://xxx.lanl.gov/abs/quant-ph/9904004

: Observational Consequences of Many-Worlds Quantum Theory

:

: Authors: Don N. Page (CIAR Cosmology Program, University of Alberta)

: Comments: 10 pages, no figures, LaTeX

: Report-no: Alberta-Thy-04-99

:

: Contrary to an oft-made claim, there are observational distinctions

: between "many-worlds" quantum theories, in which the quantum

: state "branches" without collapsing, and "single-history" quantum

: theories, in which something like a single macroscopic history

: occurs through some process such as the continual collapse or

: reduction of the quantum state. The observational distinctions

: occur as a result of processes in which observers are created

: or destroyed. One example is whether you may expect to observe

: anything within this universe after a time long compared with your

: life expectancy. Other examples are whether we would be expected

: to observe an expanding universe today in certain theories of

: quantum cosmology, or what value we might expect to observe for

: the cosmological constant.

Ah, yes, living forever as a consequence of the MWI, our favorite topic.

The paper discusses the (in)famous quantum suicide, following the

conventional reasoning that an observer in the MWI would always find

the suicide machine failing.

There is also some discussion of the role of measure in probability:

"Consider a theory of quantum cosmology that gives a quantum state for

the universe in which there are different 'worlds' with greatly different

numbers of observers. For calculating how typical various observations

are, in a single-history theory one should weight the 'worlds' purely by

how probable they are, but in a many-worlds theory, one should weight the

'worlds' not only by their quantum mechanical measures (the analogue in a

deterministic many-worlds theory of the probabilities in an indeterminstic

single-histories theory) but also by how much observation occurs with

each 'world'. This distinction leads to different predictions as to

which observations would be typical within the two types of theories."

He suggests that in MWI you should multiply the QM measure of a universe

times the number of observers to get an effective measure of the

likelihood of being an observer in that universe. This gives a boost to

universes with lots of observers and could conceivably make the universe

be big even in a cosmology where it was overwhelmingly likely to be small.

(Read it yourself to see what I mean.)

Hal

Received on Thu Apr 29 1999 - 14:50:53 PDT

Date: Thu, 29 Apr 1999 14:43:41 -0700

This is from http://xxx.lanl.gov/abs/quant-ph/9904004

: Observational Consequences of Many-Worlds Quantum Theory

:

: Authors: Don N. Page (CIAR Cosmology Program, University of Alberta)

: Comments: 10 pages, no figures, LaTeX

: Report-no: Alberta-Thy-04-99

:

: Contrary to an oft-made claim, there are observational distinctions

: between "many-worlds" quantum theories, in which the quantum

: state "branches" without collapsing, and "single-history" quantum

: theories, in which something like a single macroscopic history

: occurs through some process such as the continual collapse or

: reduction of the quantum state. The observational distinctions

: occur as a result of processes in which observers are created

: or destroyed. One example is whether you may expect to observe

: anything within this universe after a time long compared with your

: life expectancy. Other examples are whether we would be expected

: to observe an expanding universe today in certain theories of

: quantum cosmology, or what value we might expect to observe for

: the cosmological constant.

Ah, yes, living forever as a consequence of the MWI, our favorite topic.

The paper discusses the (in)famous quantum suicide, following the

conventional reasoning that an observer in the MWI would always find

the suicide machine failing.

There is also some discussion of the role of measure in probability:

"Consider a theory of quantum cosmology that gives a quantum state for

the universe in which there are different 'worlds' with greatly different

numbers of observers. For calculating how typical various observations

are, in a single-history theory one should weight the 'worlds' purely by

how probable they are, but in a many-worlds theory, one should weight the

'worlds' not only by their quantum mechanical measures (the analogue in a

deterministic many-worlds theory of the probabilities in an indeterminstic

single-histories theory) but also by how much observation occurs with

each 'world'. This distinction leads to different predictions as to

which observations would be typical within the two types of theories."

He suggests that in MWI you should multiply the QM measure of a universe

times the number of observers to get an effective measure of the

likelihood of being an observer in that universe. This gives a boost to

universes with lots of observers and could conceivably make the universe

be big even in a cosmology where it was overwhelmingly likely to be small.

(Read it yourself to see what I mean.)

Hal

Received on Thu Apr 29 1999 - 14:50:53 PDT

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