
#1
Jan2913, 01:04 PM

P: 85

Hi everybody,
i didn't wanted to create two separate threads so merged them into one. i got confused watching Brian Green explaining QM on one of his shows. He compared distribution in double slit experiments with throwing a ball on a roulette. He said that casino doesn't have to know where ball on roulette wheal is going to land, but casino knows that in the long run that he is going to get some kind of distribution. In other words, when we shoot electrons through double slit, we can't know for sure where it will go but we know that it will follow normal distribution. But in principle ball and roulette table follows Newtonian laws and if we had all the data we need, we could say with 100% certainty where will ball land. Does the same principle apply in QM i.e. if we had all the data we need we could say where the electron land? If that is the case then is QM truly random? On the other hand if we had all the data and we still couldn't predict where electron will land then it seems to me that QM is truly random. Also does qm behaving random drives stake through the heart of fatalism and predeterminism? Second question is about many worlds theory. Here is video where Sean Carroll explains a many world theory, and he uses example of a car choosing which why to go. Now, i hope that this many world theory has nothing to do with actual cars choosing which way to go i.e. when actual car chooses which way to go he doesn't create a new world, but rather all of this is on a microscopic level. Thank you. 



#2
Jan2913, 02:05 PM

Sci Advisor
PF Gold
P: 5,147

There is a formulation of QM called Bohmian Mechanics that asserts that it is possible, in principle, to determine the results with complete certainty, thus restoring determinism. However, they say there are practical limitations that make it impossible to achieve this. This is not a generally accepted viewpoint, although it is considered an acceptable interpretation since the ultimate predictions of Bohmian Mechanics are the same as QM. 



#3
Jan2913, 05:08 PM

PF Gold
P: 11,056

If you can predict an event or sequence of events with a certain level of accuracy, how can it be truly random?




#4
Jan2913, 05:29 PM

P: 85

Is QM truly random and many world theory 



#5
Jan2913, 11:25 PM

P: 82

In the case of "truly random", which usually just means "notpseudorandom", your definition is sort of the opposite of actual usage. Quantum effects are even used as school books examples of actual real world truly random processes like random number generators powered by radioactive decay. 



#6
Jan3013, 12:33 AM

Sci Advisor
PF Gold
P: 2,066

No one can say if QM is truly random or not because deterministic systems can mimic randomness. We have tests that can determine if something is pseudorandom (ie created by a deterministic process) and it has passed all those. But those tests are not 100% reliable  some very complex pseudorandom number generators pass it. So the best we can say today is as far as we can tell it's truely random but cant say for sure  nor do I think is it possible to ever do so.
Regarding MWI  yes it occurs at the quantum level but since what happens at the quantum level determines the classical under that interpretation there would be a world where the car went a different way. Personally I think the MWI is mystical mumbo jumbo  but hey its a valid interpretation and all interpretations IMHO suck in their own unique way  even the one I hold to  so simply choose the one that sucks the least  its your choice. Thanks Bill 


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