Philosophers, Physicists and Cranks

[godless dave]

The reason physicists don't try to explain consciousness is because it's a biological phenomenon.

 

[Tubbythin]

(my emphasis)

The statement in bold is incorrect. The whole point of MWI is that probabilities are the fraction of "worlds" in which an event occurs or does not occur. If you set up and participated in N quantum suicides each with 50/50 odds, your chances of survival would be 1/2^N both in MWI and in the more standard QM interpretation.

One of the things I've never really understood about MW is the interpretation of measurements when there is two possible outcomes but they are not 50/50. I'm not sure how to phrase my confusion in to a meaningful question though.

 

[The Man]

One of the things I've never really understood about MW is the interpretation of measurements when there is two possible outcomes but they are not 50/50. I'm not sure how to phrase my confusion in to a meaningful question though.

It is really just a simple matter of statistics, the more ways there are for one particular outcome to happen the greater its probability and although you may only have two particular outcomes to choose from they are not always equally probable.

In a deck of cards 12 of the 52 cards are face card (Jack, Queen or King). So if we consider the two possible outcomes as drawing a face card and drawing some other card the probability is 3/10 (12 face cards / 40 other cards).

ETA: In a MWI of a “quantum” deck of cards each of the 52 possible outcomes will happen, 12 where a face card is drawn and 40 where another card is drawn. Which one of these 52 worlds I might find myself, depends on the specific card I observe that has been drawn.

 

[Tubbythin]

It is really just a simple matter of statistics, the more ways there are for one particular outcome to happen the greater its probability and although you may only have two particular outcomes to choose from they are not always equally probable.

In a deck of cards 12 of the 52 cards are face card (Jack, Queen or King). So if we consider the two possible outcomes as drawing a face card and drawing some other card the probability is 3/10 (12 face cards / 40 other cards).

ETA: In a MWI of a “quantum” deck of cards each of the 52 possible outcomes will happen, 12 where a face card is drawn and 40 where another card is drawn. Which one of these 52 worlds I might find myself, depends on the specific card I observe that has been drawn.

But in the MWI the 12 face cards are indistinguishable. And the 40 numbered cards are also indistinguishable.
If the two probabilities were, say, 0.49 and 0.51 we'd have 98 more worlds than if the probabilities were 0.5 each?

 

[The Man]

But in the MWI the 12 face cards are indistinguishable. And the 40 numbered cards are also indistinguishable.
If the two probabilities were, say, 0.49 and 0.51 we'd have 98 more worlds than if the probabilities were 0.5 each?

Well that really depends on how one chooses to define a “quantum” deck of cards. Each card can either be unique and classifiable into different groups (face card, suit, grater then five ect..) or we could just classify the groups and say that any member of that group is indistinguishable from another member of that same group. In the latter consideration (indistinguishable) there would only be two possible worlds (face card or not) but you would still be 3 1/3 times more likely to find yourself in a world where you did not draw a face card (as there are that many more other cards then face cards). Much of this consideration of distinguishable and indistinguishable result form applying quantum aspects to something without quantum characteristic, a deck of cards, we could make a similar association of bosons and fermions. Not all bosons are indistinguishable and not all fermions are indistinguishable so a consideration where we might detect either a boson or fermion from some particle collision would result in not only those two separate outcomes, if we only look at the spin of the detected particle, but might result in a greater number of possible outcomes if we also look at some of the other aspects of the particle detected. However the probability of finding yourself in a world where you detected a boson would still depend on the ratio of fermions to bosons produced in that particle collision.

ETA: In MWI the number of possible “worlds” is the number of possible outcomes you might observe and therefore dependent on what you might choose to observe, which is one of my philosophical problems with MWI.

 

[Tubbythin]

I think my problem may be related to the fact there probably isn't a classical analogy (often the case in QM). You can talk about a deck of cards and the relative chances of getting a face card or a non-face card but this is based on counting the number of states with each outcome. In QM if you were to only measure if the outcome was face or non-face you only have two possible outcomes. So that gives two possible worlds. But one is more likely than the other. And yet they both occur at the same time. And then my brain gets tied in knots.

Not sure if this makes sense. I'm a little drunk so I might try again tomorrow.

 

[sol invictus]

Forget about QM for a moment, and think about what probabilities mean. They mean that if you repeated an experiment a bizzillion times, the results would converge to the probability distribution.

But that's precisely what MW says. It's really no more or less confusing than probabilities themselves are intrinsically.

 

[Tubbythin]

But you stated (with my bolding):

The whole point of MWI is that probabilities are the fraction of "worlds" in which an event occurs or does not occur.

For a single measurement with two possible outcomes (event and non-event if you like) there are two possible "worlds". One for event and one for non-event. To me, with the above statement, this suggests that with many worlds the probabilities should always be 50/50 for a single measurement with two possible outcomes.
So where is my understanding fundamentally wrong?

 

[sol invictus]

For a single measurement with two possible outcomes (event and non-event if you like) there are two possible "worlds". One for event and one for non-event. To me, with the above statement, this suggests that with many worlds the probabilities should always be 50/50 for a single measurement with two possible outcomes.
So where is my understanding fundamentally wrong?

It's wrong because you have an overly simplistic picture of worlds splitting off. You're imagining we should assign equal weight to every world. As you say if we did that we'd always get 50-50 odds for everything, which is nonsensical (since really there are splits happening constantly, many of which are extremely improbable events). So if we did things the way you're imagining, we'd constantly be tunneling through walls and such.

What really happens (supposedly) is that each time there's a "measurement" (really, a macroscopic interaction) the total wavefunction divides into at least two pieces, each sharply peaked around a possible outcome of the experiment. Mathematically there is no reason why the weight of those two peaks - i.e., the normalization of that piece of the wavefunction - needs to be equal.

Now, how should we interpret those weights? Well, suppose you did 1,000 identical experiments, each with 80% odds for for outcome A and 20% B. At the end you'd have many new peaks in the wavefunction - 2^1000 - each with a weight. The weights would be distributed in precisely the way one would expect if their absolute squares are probabilities.

In other words, we now have 2^1000 branches. If we assign equal weight to them all, your objection pertains - A and B occur with equal probability in a binomial distribution. But if we assign weights using our 80/20 rule at each branch, we get A and B in a binomial distribution with 80/20 probabilities.

MAybe it would help to think of each instance of the experiment above producing 5 worlds instead of 2, 4 of which are identical and correspond to outcome A and one to outcome B.

 

[blutoski]

Hi Blutoski

I was quoting from wiki

"Gardner has said that he suspects that the fundamental nature of human consciousness may not be knowable or discoverable, unless perhaps a physics more profound than ("underlying") quantum mechanics is some day developed." http://en.wikipedia.org/wiki/Martin_Gardner.

The only interpretation I made from this is

"1. The fundamentals of human conciousness is undiscoverable
2. It is discoverable only if a new physics mechanism is made available.
I suspect he refers to quantum mechanics as this is the best we have to offer at the moment.
"

Yes, and I was wondering why you brought it up. I thought it was an attempt to critique my statement that Gardner believes philosophers' interference in scientific operations to be detrimental. The passage doesn't really speak to this claim, so I have no idea why you submitted it to the discussion.

 

[Tubbythin]

MAybe it would help to think of each instance of the experiment above producing 5 worlds instead of 2, 4 of which are identical and correspond to outcome A and one to outcome B.

But thats only helpful when the two probabilities have a nice, simple denominator.

 

[Skwinty]

Yes, and I was wondering why you brought it up. I thought it was an attempt to critique my statement that Gardner believes philosophers' interference in scientific operations to be detrimental. The passage doesn't really speak to this claim, so I have no idea why you submitted it to the discussion.

Hi Blutoski
I raised the Gardner quote in response to Bens comment about science not answering questions about the fundamentals of conciousness.
I thought that Gardners statement clarified why science does not answer questions about conciousness.I include the last post where I felt I made that distinction for you.

Originally Posted by blutoski
And this supports your claim how?

Or are you just throwing out random quotes for our .sig files?

Hi Blutoski

"There has never been a physics theory which answered these sorts of questions. Galileo didn't do it, nor Newton, nor Einstein, nor Planck. All we've ever gotten from physics, to a pretty good approximation, is equations-of-motion. "

This was a statement from Ben m.
The issue was I believe, about physics answering the question "What is conciousness?". (See post 49) I then quoted Gardner in reply to Bens statement.Now , I have not read Martins books so I am unaware of the 3rd Reich and Diamat issue.

From what I have read about Gardner is that he majored in Philosophy
and I can understand his position about philosophy intefering with science in some aspects, but not as a general rule applying to all science or scientists. I would like to read his book "Introduction to the Philosophy of Science". Perhaps this will explain your statement "Gardner believes philosophers' interference in scientific operations to be detrimental."

 

[lenny]

Forget about QM for a moment, and think about what probabilities mean. They mean that if you repeated an experiment a bizzillion times, the results would converge to the probability distribution.

and when you cannot repeat the experiment a "bizzillion times"?

what do they mean then?

for instance, in a forecast that there is an 80% probability of rain a london heathrow airport tomorrow?

the return the for the earth's weather is longer than the lifetime of the sun (so you can never expect to do the experiment even twice!).

so what does it mean to say there is an 80% probability?

should a physicist worry about this question?

and if not, returning to the thread, might a philosopher who does worry about it potentially say something interesting/useful for the physicist?

at some point, physics might well leave most of the "what does it mean to say" questions to philosophy and let the science focus on the "how" questions.

every now and then, philosophy might come back a few years (or decades) later and say something useful, or even better something awkward.

 

[lenny]

being morally or philosophically problematic has no bearing on whether a scientific theory is an accurate description of reality.

agreed. and neither does understanding its history, or the details of its mathemaical formulation.

but understanding the historical, mathematical and philosophical issues may well contribute to our ability to interprete and improve the science.

 

[lenny]

Russell's maths was groundbreaking, his destruction of Hilbert's dream may have been disappointing but was certainly important. Was any of his philosophical musings of similar importance to anyone other than a philosopher.

"of similar importance" to showing that the maths of the day was fundamentally misguided? well perhaps not. but in asking for this you are raising the bar quite a bit higher than "useful to a scientist".

i'd suggest his later philosophical waffle on causality, which includes a nice demonstration that one cannot distinguish "deterministic" dynamics from "stochastic" dynamics by empirical observation, could have helped a goodly number of journeyman physicists stop banging their heads needlessly against various brick walls. (and his chicken could still be of value to many Bayesian scientists.)

the basic idea was well stated by mach much earlier (in Error and Measurement, i believe);i am not sure if you'd consider that "Mach the Scientist" or "Mach the Philosopher". but then i do not feel the distinction within individuals makes much sense...

 

[lenny]

The 'Should we do it?' question is indeed in the domain of philosophy but in moral philosophy not the philosophy of science. ... Unless they show some utility, what are they worth, certainly nothing to a scientist.

so what about a "how should we do it" question, say, in the statistical design of experiments.

i generally hate biological examples in physics arguments, but i fear this one fits best:

you are testing for the effectiveness of a new drug.

you design a clinical trial, but wish to stop the trial early if the drug is shown to be either useless or harmful. doing the statistics is straight-forward once you know the number of patients the trial impacts, and there is the rub: is the "number of patients" the number of people in the trial -or- the number of people who will have this disease in the next 50 years -or- other.

answering this question is critical to the design of the scientific experiment, yet it is arguably not a scientific question.

philosophers demonstrate utility here, for example.

 

[Skwinty]

(my emphasis)

The statement in bold is incorrect. The whole point of MWI is that probabilities are the fraction of "worlds" in which an event occurs or does not occur. If you set up and participated in N quantum suicides each with 50/50 odds, your chances of survival would be 1/2^N both in MWI and in the more standard QM interpretation.

Hi Sol,
thanks for that info. Does any one correct the mistakes in wikopedia?

 

[Acleron]

so what about a "how should we do it" question, say, in the statistical design of experiments.

i generally hate biological examples in physics arguments, but i fear this one fits best:

you are testing for the effectiveness of a new drug.

you design a clinical trial, but wish to stop the trial early if the drug is shown to be either useless or harmful. doing the statistics is straight-forward once you know the number of patients the trial impacts, and there is the rub: is the "number of patients" the number of people in the trial -or- the number of people who will have this disease in the next 50 years -or- other.

answering this question is critical to the design of the scientific experiment, yet it is arguably not a scientific question.

philosophers demonstrate utility here, for example.

I'm not sure of the validity of this example, a lot of work will have been done to arrive at the point of a phase II study. This research would not have been performed if there wasn't some sort of gain to be made.

However assuming that a drug had suddenly fallen into the hands of researchers with full toxicology already available, I presume you are asking how many people should be in the trial. That's pretty much already available through probability statistics, no philosophy of any description required.

Perhaps you are asking how many people should be tested given the number of people who will suffer from the disease over a period of time. Pragmatically, this question is answered by the severity of the disease, minor diseases, in terms of numbers, get studied less. But let's assume all the major diseases have been studied and we are into the area of not being able to easily find enough patients for a study, which minor diseases should we study? If a philosopher has an answer to that please give us the logic. If it's a logical answer, an equation should be available, so to make it easy, just supply the equation.

 

[sol invictus]

and when you cannot repeat the experiment a "bizzillion times"?

what do they mean then?

Not much, mathematically speaking. And yet I'm perfectly willing to make a bet once if I know the odds, so apparently they mean something.

for instance, in a forecast that there is an 80% probability of rain a london heathrow airport tomorrow?

I have never understood what those probabilities are supposed to mean. Is it that the model certainly predicts rain, but with enough theoretical/measurement uncertainty to bring the likelihood down to 80%? That it predicts rain at some point, but only an 80% chance it will be tomorrow? That it predicts rain over 80% of the area in question? Or rain, but only for 80% of the day? Or rain over 80% of a large area that includes Heathrow?

should a physicist worry about this question?

Yes.

and if not, returning to the thread, might a philosopher who does worry about it potentially say something interesting/useful for the physicist?

I doubt it.

 

[69dodge]

so what about a "how should we do it" question, say, in the statistical design of experiments.

i generally hate biological examples in physics arguments, but i fear this one fits best:

you are testing for the effectiveness of a new drug.

you design a clinical trial, but wish to stop the trial early if the drug is shown to be either useless or harmful. doing the statistics is straight-forward once you know the number of patients the trial impacts, and there is the rub: is the "number of patients" the number of people in the trial -or- the number of people who will have this disease in the next 50 years -or- other.

answering this question is critical to the design of the scientific experiment, yet it is arguably not a scientific question.

philosophers demonstrate utility here, for example.

I don't understand. What is the question?

What do you mean by "doing the statistics"? What statistics?