# RE: normalization

From: Jacques M. Mallah <jqm1584.domain.name.hidden>
Date: Wed, 2 Feb 2000 13:40:18 -0500 (EST)

On Wed, 2 Feb 2000, Higgo James wrote:
> Ah, so Jacques believes in QTI for cats

Hell no. You obviously didn't read what I wrote
carefully. Besides, my impression was that you no longer believe QTI.
As I explicitly made clear with the last computation (and as would
have been obvious anyway) the fact that the Cat's measure is reduced by
half, on average, shortens the Cat's life.
The 100% is only a *conditional* probability, given that the Cat
survived, that the Cat would survive. Hence it is pretty silly to compute
it. This goes to show why I said the Schrodinger's Cat example was a bad
one to use as it is conducive to letting people make such errors.

> > -----Original Message-----
> > From: Jacques M. Mallah [SMTP:jqm1584.domain.name.hidden]
> > Sent: Tuesday, 01 February, 2000 10:22 PM
> > To: everything-list.domain.name.hidden
> > Subject: Re: normalization
> >
> > On Tue, 18 Jan 2000 GSLevy.domain.name.hidden wrote:
> > > jqm1584.domain.name.hidden writes:
> > > > On Tue, 18 Jan 2000 GSLevy.domain.name.hidden wrote:
> > > > > jqm1584.domain.name.hidden writes:
> > > > > > The RSSA is not another way of viewing the world; it is a
> > > > > > category error.
> > > > >
> > > > > I use the RSSA as the basis for calculating what I call the
> > relative
> > > > > probability, in this group the first person probability, or,
> > equivalently,
> > > > > the probability conditional on the life of the observer. The ASSA
> > is by
> > > > > extension, the assumption for calculating the 3rd person
> > probability.
> > > > >
> > > > > Let us perform a thought experiment.
> > > > > Imagine that you are the scientist in the Schroedinger cat
> > experiment.
> > > >
> > > > Scratch that. Right now let's stick to the example with Bruno and
> > > > the 3 cities, because it's better for the current point.
> > > > Suppose Bruno, in 1999, wants to know if he is more likely to be
> > > > in Washington or in Moscow during 2001.
> > > > First of all, that is not a well defined question, because
> > > > "Bruno" must be defined. Suppose we define it to mean the set of all
> > > > Bruno-like observations, where by "Bruno-like" we can assume we know
> > what
> > > > qualifies.
> > > > But then the question becomes meaningless, because it is 100%
> > > > certain that he will be in *both* cities. A 3rd person would have to
> > > > agree with that, he is in *both* cities.
> > > > So let's ask a meaningful question. Among the set of Bruno-like
> > > > observations in 2001, what is the effective probability of such an
> > > > observation being in Moscow?
> > > > This is just a conditional effective probability so we use the
> > > > same rule we always use:
> > > > p(Moscow|Bruno in 2001) =
> > > > M(Moscow, Bru. 2001) / [M(Moscow, Bru. 2001) + M(Washington, Bru.
> > 2001)]
> > > > where M is the measure.
> > > > So in this case the conditional effective probability of him
> > > > seeing Moscow at that time is 10%, and in *1999* he knows he should
> > brush
> > > > up on his English because his future 'selves' will be affected by
> > that.
> > > >
> > >
> > > Fine, you have computed the third person probability.
> >
> > Bullshit. There is no such thing. As I said, a 3rd person would
> > say that he is in both cities for certain. What I computed was the
> > effective probability for Bruno's.
> >
> > > Unfortunately, your
> > > example does not have the option of having an independent observer, and
> > > therefore does not illustrate the concept I am trying to communicate.
> >
> > How can an example not have an option? Evidently your concept of
> > "independent observer" is closely tied to QM physics, and the fact that I
> > am discussing a different situation messes it up.
> >
> > is
> > > with an observer who is not threatened with death and a subject who is.
> > It is
> > > the only way to bring out the concept of relative probability or 1st and
> > 3rd
> > > person probability.
> >
> > I have another view, namely, that the example you mentioned
> > (Schrodinger's Cat) is conducive to letting you make your errors, and it
> > is the "only way" because your views don't work in a more general
> > situation.
> > But because you used the magic word, OK, I'll illustrate the same
> > methods I used above, using the Cat.
> >
> > As far as the human experimenter can tell, the experiment has a
> > 50% chance to kill the Cat.
> > Suppose the Cat, before the experiment, wants to know if he is
> > more likely to be alive or dead after the experiment.
> > First of all, that is not a well defined question, because
> > "the Cat" must be defined. Suppose we define it to mean the set of all
> > Cat-like observations, where by "Cat-like" we can assume we know what
> > qualifies.
> > Now let's ask a more precise question. Among the set of Cat-like
> > observations after the experiment, what is the effective probability of
> > such an observation being of a live Cat?
> > This is just a conditional effective probability so we use the
> > same rule we always use:
> > p(alive|Cat sees after experiment) = M(alive, Cat after) / M(alive, Cat
> > after)
> > where M is the measure.
> > So in this case the conditional effective probability of him
> > seeing that he is alive, given that he makes the observation after the
> > experiment, is 100%. This is the quantity that is analagous to the 10%
> > effective probability Bruno had for being in Moscow (in 2001), according
> > to the ASSA. (While the RSSA claimed 90% for Bruno, but would agree with
> > 100% for the Cat.)
> > OK. Obviously this was a rather trivial example of a conditional
> > effective probability. Let's ask one more question. Assume that the Cat
> > was 10 years old at the time of the experiment, and would have lived to 20
> > if he had not been subjected to the experiment. Over his lifetime, what
> > is the effective probability for him to be older than 10?
> > p(10+|Cat) = M(10+|Cat) / [M(10+|Cat) + M(<10|Cat)] = .5 / (.5 + 1) = 1/3
> >
> > - - - - - - -
> > Jacques Mallah (jqm1584.domain.name.hidden)
> > Physicist / Many Worlder / Devil's Advocate
> > "I know what no one else knows" - 'Runaway Train', Soul Asylum
> > My URL: http://pages.nyu.edu/~jqm1584/
>
>
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Received on Wed Feb 02 2000 - 10:44:44 PST

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