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Let me first briefly introduce myself. I was trained as a

theoretician, and did QED and particle physics, albeit quite a few

years ago. But, for most of my adult life I've worked in business,

doing statistics, modeling, and consulting.

My question is: why is quantum probability, different from "classical

probability?" After years of working with probability I'm more

convinced than ever that the two are basically not different --

probability is probability. (Certainly the computational approaches

are quite different)

When I do a coin toss, I do not know what will happen, other than the

chances will be equal for either possible outcome. But when the coin

lands I know whether we are talking heads or tails, and the state of

my mind goes from the uncertainty of 50-50 chances, to full certainty

of the outcome. For practical purposes, the wave packet, the

probability function, collapses to the outcome, which ends up in

a "pure" state. In applications of probability to marketing,

medicine, sports, finance, and so on, we typically finesse the actual

collapse, knowing as we do the brain/mental processes that govern our

change of knowledge are a bit beyond our ken, at least for the

present.

When you do an electron scattering experiment, for example, once the

counters start registering events, you know what happened -- at time

t, counter A went blip, so we know with certainty that an electron

hit counter A. For that matter, when we make a classical computation

of the radiation patterns from an antenna with a new configuration,

we certainly will do measurements to determine the efficacy of our

computations. Once we do the measurements, we reduce an initial

uncertainty to certainty -- does this not reduce the wave packet?

So, my question is, once again, why is quantum probability different

from the probability that many, many nonphysicists use -- with great

success, and without ever worrying about any wave packet reduction?

Regards,

Reilly Atkinson

(Again I agree that the Schrodinger equation for the wave function,

and a stochastic dynamics equation for probabilities of consumer

purchasing behavior are very different -- conceptually and

mathematically. The issue is what the computational results mean.) - ormand2000 wrote:
>

IMHO, there is no real difference, using the MWI interpretation. And

> My question is: why is quantum probability, different from "classical

> probability?" After years of working with probability I'm more

> convinced than ever that the two are basically not different --

> probability is probability. (Certainly the computational approaches

> are quite different)

your examples are quite nice.

Any truly random events always represent branches of the multiverse,

whether the events are macroscopic or microscopic.

And of course in the MWI there is no collapse; by looking at the result

of the experiment we just find out which branch we are in, and we know

that the other branches are just as real.

-- Gary Oberbrunner - At 01:23 01/04/03 +0000, ormand2000 wrote:
>[snip] Once we do the measurements, we reduce an initial

But then you follow Heisenberg (at least with respect to some of

>uncertainty to certainty -- does this not reduce the wave packet?

his writing) taking the wave as a description of our (psychological

ignorance).

>So, my question is, once again, why is quantum probability different

Because quantum probability is given by the square of a "probability

>from the probability that many, many nonphysicists use -- with great

>success, and without ever worrying about any wave packet reduction?

amplitude", and we have evidence that that amplitude behaves

like a wave so that it interferes independently of

the observers. How could our "ignorance" interferes with reality?

Many World, or many minds helps to figure out what happens ...

Bruno