Is there inherent, observable randomness in the universe?

[Darryl_P]

Before you tell me that Quantum Mechanics says there is, consider this:

The only way we can know about a particle's position is via our senses, the most appropriate of which is vision. For our eyes to detect something we need photons to transmit information.

In the case of particles on a small scale similar to photons it stands to reason that the ability of photons to transmit reliable information is restricted, just as you could not get a very accurate picture on your TV screen or digital camera if it only used 1 or 2 pixels instead of several million.

It is my understanding that this limitation of photons' ability to transmit information is the key to the uncertainty principle, and therefore what seems like inherent randomness in the universe really isn't. The particle is there, only we can never know for sure, no matter how accurate our measuring devices become. The limitation applies to us and not the universe.

Just as Sklansky is looking for evidence to support the existence of God via his threads on miracles, I am looking for evidence to support atheism ie. that randomness actually exists in the observable universe and not just in our minds.

I currently am a believer in God, but if I see convincing evidence about the above, then I would seriously begin considering atheism. Any help, info., links, etc. would be greatly appreciated.

[DougShrapnel]

Do I get any points if I where to demostrate that the universe itself is arbitrary?

[bluesbassman]

[ QUOTE ]
Before you tell me that Quantum Mechanics says there is, consider this:

The only way we can know about a particle's position is via our senses, the most appropriate of which is vision. For our eyes to detect something we need photons to transmit information.

In the case of particles on a small scale similar to photons it stands to reason that the ability of photons to transmit reliable information is restricted, just as you could not get a very accurate picture on your TV screen or digital camera if it only used 1 or 2 pixels instead of several million.

It is my understanding that this limitation of photons' ability to transmit information is the key to the uncertainty principle, and therefore what seems like inherent randomness in the universe really isn't. The particle is there, only we can never know for sure, no matter how accurate our measuring devices become. The limitation applies to us and not the universe.


[/ QUOTE ]

This interpretion of the uncertainty principle is incorrect. Randomness is a fundamental, inherent property of the universe, rather than a practical limitation on measurement devices. Here is a Wilkpedia link which explains exactly that:

Uncertainty Principle (http://en.wikipedia.org/wiki/Uncertainty_principle)

[ QUOTE ]

Just as Sklansky is looking for evidence to support the existence of God via his threads on miracles, I am looking for evidence to support atheism ie. that randomness actually exists in the observable universe and not just in our minds.

I currently am a believer in God, but if I see convincing evidence about the above, then I would seriously begin considering atheism. Any help, info., links, etc. would be greatly appreciated.

[/ QUOTE ]

Read the link I already provided. To the best of our knowledge, the universe is inherently nondeterministic. Accept it.

Regardless, whether the physical laws are ultimately deterministic or nondeterministic has nothing at all to do with whether "god" exists. Presumably, this "god" could have "designed" the universe to be nondeterministic. (In fact, some theists argue precisely that to rectify the contradiction between on omniscient god and free will.)

I'm an atheist not because of the uncertainty principle, but rather because the concept of "god" is arbitrary and meaningless.

[ QUOTE ]
The particle is there, only we can never know for sure, no matter how accurate our measuring devices become. The limitation applies to us and not the universe.

[/ QUOTE ]

I'm afraid you don't fully understand the results of the double slit experiment with single particles.

from http://www.space.com/searchforlife/quantum_astronomy_041111.html:

"So light is both a particle and a wave. OK, kind of unexpected (like Jell-O) but perhaps not totally weird. But the double slit experiment had another trick up its sleeve. One could send one photon (or “quantum” of energy) through a single slit at a time, with a sufficiently long interval in between, and eventually a spot builds up that looks just like the one produced when a very intense (many photons) light was sent through the slit. But then a strange thing happened. When one sends a single photon at a time (waiting between each laser pulse, for example) toward the screen when both slits are open, rather than two spots eventually building up opposite the two slit openings, what eventually builds up is the interference pattern of alternating bright and dark lines! Hmm… how can this be, if only one photon was sent through the apparatus at a time?

The answer is that each individual photon must – in order to have produced an interference pattern -- have gone through both slits! This, the simplest of quantum weirdness experiments, has been the basis of many of the unintuitive interpretations of quantum physics. We can see, perhaps, how physicists might conclude, for example, that a particle of light is not a particle until it is measured at the screen. It turns out that the particle of light is rather a wave before it is measured. But it is not a wave in the ocean-wave sense. It is not a wave of matter but rather, it turns out that it is apparently a wave of probability. That is, the elementary particles making up the trees, people, and planets -- what we see around us -- are apparently just distributions of likelihood until they are measured (that is, measured or observed). So much for the Victorian view of solid matter!"

This uncertainty isn't really a limitation due to our ability to measure precisely, but instead, until measured, the particle is in effect ("physically") everywhere at once (distributed according to its probability function). There has been no neat explanation of how this can be, only quantification of the consequences. To explain this behavior in a manner that humans can understand will (I believe) require a fundamental breaking down of everything we think we "know" about matter and the universe, on a scale that surpasses even relativity in its "weirdness". Bottomline is the universe is far more "strange" than we can fully understand right now -- but we have the tools to quantify and predict its behavior on a probability basis! (This doesn't necessitate "randomness", either, however. It could be deterministic based on causes we cannot observe at this time, like vibrations in another dimension for example.)

[Trantor]

[ QUOTE ]
Before you tell me that Quantum Mechanics says there is, consider this:

The only way we can know about a particle's position is via our senses, the most appropriate of which is vision. For our eyes to detect something we need photons to transmit information.

In the case of particles on a small scale similar to photons it stands to reason that the ability of photons to transmit reliable information is restricted, just as you could not get a very accurate picture on your TV screen or digital camera if it only used 1 or 2 pixels instead of several million.

It is my understanding that this limitation of photons' ability to transmit information is the key to the uncertainty principle, and therefore what seems like inherent randomness in the universe really isn't. The particle is there, only we can never know for sure, no matter how accurate our measuring devices become. The limitation applies to us and not the universe.

Just as Sklansky is looking for evidence to support the existence of God via his threads on miracles, I am looking for evidence to support atheism ie. that randomness actually exists in the observable universe and not just in our minds.

I currently am a believer in God, but if I see convincing evidence about the above, then I would seriously begin considering atheism. Any help, info., links, etc. would be greatly appreciated.

[/ QUOTE ]
Even as a "devout" atheist I would not say that proof of randomness in the universe would be a grounds for denying the existance of a God.

As a physicist I offer the following brief comments.

The inherent randomness of the universe exhibits itself at small scales where the most appropriate observational tool is most defiitely not the eye. When did you last see an atom?


The photon / uncertainty example you mention is a a sort of classical explanation of Heisenburg's uncertainty principle i respect of the double slit experiment but the uncertainty principle is not a result of this sort of observational interaction.

As to quantum mechanics, I'm afraid I have to refer to this as this is the explanation of how things are. It is inherent in this theory, the randomness you talk about. No test to date has disproved quantum mechanics and the inherent "randomness" of aspects of the theory.

Quantum electrodynamics, in particular, is the most accurate theory known to man at the present time.

The thhing to bear in mind is that uncertainty of quantum mechanics does not arise from the paucity of the measurement apparatus but is a fundamental of the theory (as understood today). There are efforts to remove the randomness by hidden variable theory but there is no demonstration that this view is correct.

So, the universe as presently understood appears inherently random in certain aspects, ie in regimes where quantum mechanics applies.

[kevyk]

Before the late 1960's, there were in fact two competing interpratations of the Heisenberg uncertainty principle. The 'realist' school believed, as you do, that a particle does have a definite position and momentum, but that they are unknowable (or at least not predicted by quantum theory). The competing 'Copenhagen' interpretation, which has become the accepted one, holds that a particle does not have a definite position or momentum until a measurement is taken.

Believe it or not, this is a testable proposition. In 1965, John Bell proposed an experiment to rule the "hidden variable theory" in or out. Wikipedia explains here (http://en.wikipedia.org/wiki/Bell%27s_theorem#Bell.27s_thought_experiment) and here (http://en.wikipedia.org/wiki/Bell%27s_theorem).

Repeated experiments have shown that the universe violates Bell's inequality and therefore does exhibit randomness.

[Darryl_P]

I am familiar with the double slit experiment, or at least the key point it makes about a particle having to go through both at once, and it is very interesing indeed, but as you said in your last few lines, I don't see how it proves inherent randomness since there could theoretically be a host of explanations involving knowledge we don't have yet, not all of which involve inherent randomness.

Instead I see humans invoking prob+stats the same way they do for everything else, ie. to give at least partial explanations for something they don't have full explanations for -- which is very good indeed and much better than nothing IMO.

[chezlaw]

[ QUOTE ]
Before the late 1960's, there were in fact two competing interpratations of the Heisenberg uncertainty principle. The 'realist' school believed, as you do, that a particle does have a definite position and momentum, but that they are unknowable (or at least not predicted by quantum theory). The competing 'Copenhagen' interpretation, which has become the accepted one, holds that a particle does not have a definite position or momentum until a measurement is taken.

Believe it or not, this is a testable proposition. In 1965, John Bell proposed an experiment to rule the "hidden variable theory" in or out. Wikipedia explains here (http://en.wikipedia.org/wiki/Bell%27s_theorem#Bell.27s_thought_experiment) and here (http://en.wikipedia.org/wiki/Bell%27s_theorem).

Repeated experiments have shown that the universe violates Bell's inequality and therefore does exhibit randomness.

[/ QUOTE ]
I'm not an expert but as I understand it Bell inequality is an attempt to show that there are random phenomena or the speed of light can be exceded.

Even if Bells test is passed (failed?) to any precision it could be that the speed limit is high enough to maintain deterministism in a way that conforms with relativity.

Imagine a computer simulation that runs much faster than the speed of light but simulates a universe with the speed of light constant as per relativity. QM could be a window into the nature of the simulation rather than evidence of randomness. [models could then be created that don't require a computer simulation].

This could all be rubbish.

chez

[Darryl_P]

[ QUOTE ]
When did you last see an atom?


[/ QUOTE ]

OK you have a point there. I suppose I should have said we use measuring instruments which need light to transmit the information much like our eyes do, as opposed to our other sensory organs. Or is this not true either?

[ QUOTE ]
There are efforts to remove the randomness by hidden variable theory but there is no demonstration that this view is correct.


[/ QUOTE ]

So you are saying that a minority of physicists believe there is an underlying deterministic process behind the uncertainty principle?

Is it safe to say, then, that inherent randomness of the universe has not been *proven* (at least to the extent that something can be proven in physics), even though it is widely (but not unanimously) believed among leading physicists?

[Darryl_P]

[ QUOTE ]
Repeated experiments have shown that the universe violates Bell's inequality and therefore does exhibit randomness.

[/ QUOTE ]

According to Trantor's post above it seems some physicists are still working on a hidden variable theory. I wonder why they weren't convinced!?

Based on all the responses so far I've clicked on some of your links and done some digging myself and I found a couple of interesting things:

1) A poll of 72 leading physicists conducted by the American researcher David Raub in 1995 and published in the French periodical Sciences et Avenir in January 1998 recorded the following results:

Yes, I think MWI is true 58%
No, I don't accept MWI 18%
Maybe it's true but I'm not yet convinced 13%
I have no opinion one way or the other 11%
link (http://www.absoluteastronomy.com/encyclopedia/m/ma/many-worlds_interpretation_of_quantum_mechanics.htm)

2) Q13 Is many-worlds a deterministic theory?
Yes, many-worlds is a deterministic theory, since the wavefunction obeys a deterministic wave equation at all times. All possible outcomes of a measurement or interaction (See "What is a measurement?") are embedded within the universal wavefunction although each observer, split by each observation, is only aware of single outcomes due to the linearity of the wave equation. The world appears indeterministic, with the usual probabilistic collapse of the wavefunction, but at the objective level, which includes all outcomes, determinism is restored.
Some people are under the impression that the only motivation for many- worlds is a desire to return to a deterministic theory of physics. This is not true. As Everett pointed out, the objection with the standard Copenhagen interpretation is not the indeterminism per se, but that indeterminism occurs only with the intervention of an observer, when the wavefunction collapses. (See "What is the Copenhagen interpretation?")
link (http://www.hedweb.com/everett/everett.htm#deterministic)

So the many-worlds interpretation, which is in contradiction with the Copenhagen interpretation, looks like it's widely believed among leading physicists. If it's the correct one, then QM is a lot of things, but it's not evidence of inherent randomness in the universe.

[Siegmund]

Even if you don't care for the Copenhagen interpretation, radioactive decay still appears to be a completely random process.

It has a characteristic rate for a given isotope - but beyond that, we are completely unable to predict in advance when a given atom will decay, and completely unable to influence that rate of decay. Maybe we just aren't able to look in the right place, to "see what time the fuse is set for?" No. The distribution of decay times is exponential; each atom has no memory at all of its past, just as likely to decompose its first minute whether it was freshly made in a reactor or has been around since before the formation of the earth.

[kevyk]

Hi Chez,

It has been a while since I studied this, but I don't believe that the Bell experiments inherently mean "there is no hidden variable or the speed of light can be exceeded." I believe that the results indicate that both are true.

First, consider the result that says before the measurement the particle's spin is indeterminate. I believe that this is a function of the fact that when the particle's spin is measured, it is with respect to a random set of axes. If the particle had a definite spin, it would spin about a definite axis. This would produce a quantifiable disparity in the number of times you counted it as "spin-up" vs. "spin-down" as opposed to a particle which is forced to decide by your measurement what axis it is spinning with respect to.

The experiments also uphold the quantum-mechanical prediction that entangled particles instantly "know" whether the other has been measured. Measurements of entangled particle B reveal that it knows A is "spin-up" before a light signal relaying that information could have arrived.

Most physicists get around this seeming violation of general relativity by noting that no information actually traveled faster than light. After all, the two spin-measurers don't know that locality has been violated until they can get together and compare notes--neither initially knows who made the first measurement.

Also, it's useful to note that some things (never physical objects) are known to move faster than light. An example: place a lamp in the middle of the universe, then move a shade across it at any speed. The shade will block a certain amount of visual angle per time, which means that if you move far enough away from the light, the edge of the shadow produced will be moving at faster than c. The point is, shadows aren't real things, so it doesn't mean much when they seemingly violate special relativity.

There are several nonlocal hidden-variable die hards out there, but it's my impression that they have to use pretty fanciful contortions to make their theories match experiment. I will look back over my old textbooks to see if I'm forgetting something, but that will have to wait until tomorrow evening (they're halfway across town at my parents' house).

Later,
Kevin

[Darryl_P]

[ QUOTE ]
Even if you don't care for the Copenhagen interpretation, radioactive decay still appears to be a completely random process.


[/ QUOTE ]

This is very interesting and looks to be a strong argument, but to me it again simply shows our own limitations, ie. our lack of understanding of what causes radioactive decay.

A weakening factor is that, unlike the uncertainty principle which claims we can NEVER know the position of certain particles, this example only shows that we DON'T AT THE MOMENT know what causes a particular atom to decay.

In my limited browsing I found this experiment (http://64.233.183.104/search?q=cache:cuTUOEfaMzYJ:redshift.vif.com/JournalFiles/V08NO2PDF/V08N2FAL.pdf+radioactive+decay+deterministic&hl=hu ) which shows that one type of decay may be caused by neutrinos, an assertion which, if true, would suggest that the seemingly random behavior of decaying atoms is only pseudo-random.

It also makes this statement:

"In contemporary physics, it is well-known and widely accepted that radioactive decay is governed by quantum-mechanical tunnel effects"

which I don't really understand, but if it's *governed* by QM, then doesn't its determinism/randomness depend on QM's determinism/randomness?

[Darryl_P]

[ QUOTE ]
Regardless, whether the physical laws are ultimately deterministic or nondeterministic has nothing at all to do with whether "god" exists. Presumably, this "god" could have "designed" the universe to be nondeterministic. (In fact, some theists argue precisely that to rectify the contradiction between on omniscient god and free will.)


[/ QUOTE ]

I agree that inherent randomness would not *prove* the non-existence of God, just as verification of a miracle would not prove God's existence. I didn't mean to claim that, though, only that my own belief system depends heavily on it. My reason for creating this thread is to find out more about determinism vs. randomness and not to try to convince anyone that my belief system is good or correct.

Having said that, I've noticed a lot of atheists rely on the ultimacy of randomness, though, and so if that were weakened, their beliefs could be weakened as well.

[David Sklansky]

"It has a characteristic rate for a given isotope"

Do we know what causes that rate?

[ QUOTE ]
I've noticed a lot of atheists rely on the ultimacy of randomness,

[/ QUOTE ]

No, you've seen a lot of theists argue against the ultimacy of randomness. But I have not read any atheist "rely on it", since they are not the ones making any broad-brushed claims (see theists) to need shaky foundations to rely upon.

[chezlaw]

Hi Kevin

Thanks for the thoughful reply. I'n not pushing any non-local agenda here and I'm well beyong my knowledge of QM and relativity.

However, QM and some of its wierder phenomena remind me strongly of something else that is compatible with classical physics, an efficient computer program that simulates a classical universe. [I'm not saying there is any reason to believe thats what going on but if my idea has merit then it means there must be a way of making QM, relativity and determinism consistent which need not involve a computer simulation].

The specific points you raise:
[ QUOTE ]
This would produce a quantifiable disparity in the number of times you counted it as "spin-up" vs. "spin-down" as opposed to a particle which is forced to decide by your measurement what axis it is spinning with respect to.

[/ QUOTE ]
The 'forced to decide by your measurement' is exactly how an efficient simulation would work. No efficient program would calculate values until they are needed. While all thats needed is the probability function then stick with that, when a value is required then collapse the probability function into a value using a deterministic pseudo-rnd. [it must be best to work this way as most of the time the value is never measured]


[ QUOTE ]
The experiments also uphold the quantum-mechanical prediction that entangled particles instantly "know" whether the other has been measured. Measurements of entangled particle B reveal that it knows A is "spin-up" before a light signal relaying that information could
have arrived.

[/ QUOTE ]
In the simulation this is easily understood. The up and down spins are entangled in a probability function but A must be up and B down (or vice verca) when/if they are given values.

Once the up/down of A is forced to be given a value (measured) then the up/down of B is forced to be given the opposite value at the same time, the same time being as fast as the computer can do it. This is necessarily many orders of magnitudes faster than the speed of light within the simulation, which gives the appearance of instant action at a distance.

Its a fanciful idea that came to me when I was working on some artificial life simulations. For efficiancy reasons, a just in time evaluation of values is almost neccesary. It also makes sense to impose a speed limit within the system which prevents a simple newtonian model.

Fanciful idea that floats or a dead duck?

chez

[kevyk]

[ QUOTE ]
No efficient program would calculate values until they are needed.[it must be best to work this way as most of the time the value is never measured]


[/ QUOTE ]

This is pretty much how the the equations of QM work. A particle's quantum state is represented by a probability density function (psi) in either position or momentum space. Psi can be represented as a vector in an infinite-dimensional Hilbert space, because all psi's are orthogonal to each other. "Measurements" are represented in this theoretical framework by non-commuting operators which return an eigenstate of psi. The fact that the operators don't commute (meaning that first operating on psi with the position operator, then with the momentum operator gives different results than the reverse) is in some sense the guts of QM.

Most interesting problems in QM involve particles or systems of particles which are in a superposition of quantum states, where psi = a*psi1 + b*psi2 + ..., in which case the probability of measuring the particle to be in state psi1 is a^2/(a+b+...)^2.

Where I think you go wrong is in saying that there's something deterministic going on in the measurement process. While you could be right, there's no evidence to support this, and QM works just fine without it.

You sound like you know probability and linear algebra pretty well--a book in introductory QM might be acessible to you. H.J. Griffiths has written a pretty good one.

[BruceZ]

[ QUOTE ]
"It has a characteristic rate for a given isotope"

Do we know what causes that rate?

[/ QUOTE ]

For alpha decay, the energy of the emitted alpha particle determines the probability that it can escape the strong electromagnetic attraction of the nucleus via a quantum mechanical phenomenon called barrier penetration. For different nuclei, the decay energy of the alpha particle varies so greatly that it causes the rate of decay to range over 24 orders of magnitude, from 2 million decays per second for Polonium 212 to over 10^18 seconds per decay for Uranium 238.

The total energy of the emitted alpha particle (4 - 9 MeV) is always much less than the nucleus' barrier potential (~30 Mev). The fact that the alpha particle can escape at all can only be understood as a quantum probabilistic phenomenon, whereby the particle’s wave function psi penetrates through the barrier region where classically the particle would not be allowed, and then affords the particle a non-zero probability of popping out on the other side.

[Trantor]

[ QUOTE ]
[ QUOTE ]
Even if you don't care for the Copenhagen interpretation, radioactive decay still appears to be a completely random process.


[/ QUOTE ]

This is very interesting and looks to be a strong argument, but to me it again simply shows our own limitations, ie. our lack of understanding of what causes radioactive decay.

A weakening factor is that, unlike the uncertainty principle which claims we can NEVER know the position of certain particles, this example only shows that we DON'T AT THE MOMENT know what causes a particular atom to decay.

In my limited browsing I found this experiment (http://64.233.183.104/search?q=cache:cuTUOEfaMzYJ:redshift.vif.com/JournalFiles/V08NO2PDF/V08N2FAL.pdf+radioactive+decay+deterministic&hl=hu ) which shows that one type of decay may be caused by neutrinos, an assertion which, if true, would suggest that the seemingly random behavior of decaying atoms is only pseudo-random.

It also makes this statement:

"In contemporary physics, it is well-known and widely accepted that radioactive decay is governed by quantum-mechanical tunnel effects"

which I don't really understand, but if it's *governed* by QM, then doesn't its determinism/randomness depend on QM's determinism/randomness?

[/ QUOTE ]

This is a fascinating subject and your questions go to the heart of the fundamental nature of the universe. i suggest you look for a book on basic quantum theory. not university texts but one of the many aimed at the non-science "layman".

They will give you a feel of exactly what you are enquiring about and an introductory book would easily and quickly answer these questions you have posed.

For example, for some events the probability of an event happening is calculable by quantum theory (so you might say determinable by quantum mechanics) but the actual outcome of of a given measurement is not.

The apparant randomness is not an uncertainty due to limits of our scientific knowledge to predict an event. We "know" (in that QM has been extensively tested and not found wanting)that the uncertainty is a fundamental character of the universe at small scales.

Quntum theory absolutely does not say you can never know the position of a particle, just to pick up on another point .

Anyway, I really would urge you to continue your investigations into this and other areas of science, if you haven't already!

[Trantor]

[ QUOTE ]


First, consider the result that says before the measurement the particle's spin is indeterminate. I believe that this is a function of the fact that when the particle's spin is measured, it is with respect to a random set of axes. If the particle had a definite spin, it would spin about a definite axis. This would produce a quantifiable disparity in the number of times you counted it as "spin-up" vs. "spin-down" as opposed to a particle which is forced to decide by your measurement what axis it is spinning with respect to.

[/ QUOTE ]

If the particle had a definite spin, ie as measured by some apparatus, then its spin is definite and if the axis of measurement were not aligned with the axis the measurement would have no spin component on that axis detected, if it was aligned it would measure all its spin along that axis. this is straightforward QM.


BUT, I'm not sure this is what you have in mind. If a spin is unmeasured and can be either up or down 50% then it can be up or down 50% relative to ANY orientation of axis. The uncertainty is not because we don't know the spin through absence of measurement but it is actually in some direction. It is in a supperposition of up and down relative to all orientations of axes.

[atrifix]

When quantum physics was first getting off the ground in the early 20th century, people were aware of statistics and indeterminism but thought it was just inaccuracy in our measuring devices--so no one proposed indeterminism as an actual theory, although they did use it in their calculations. The Heisenberg uncertainty principle states that these uncertainties are not caused by impairments in measuring devices, but are a fundamental part of the world. Many physicists had trouble coming to grips with this (Einstein is the most notable one), but repeated experiments in the later half of the century, involving single photons as well as single electrons, showed this to be more or less true.

Now, it may just be that our knowledge is limited. Nothing can ever be PROVEN in physics. It's possible that quantum mechanics will in fact be overturned for a deterministic theory. However, QM is the most successful physical theory to date, so it is probably correct given our current understanding.

Also, MWI is perfectly consistent with everything found so far in QM. If you consider many-worlds (possibly infinite) to be deterministic, then there is no contradiction.

[maurile]

[ QUOTE ]
So you are saying that a minority of physicists believe there is an underlying deterministic process behind the uncertainty principle?

[/ QUOTE ]
There are a few deterministic interpretations of QM (e.g., Everett's many-worlds interpretation), but most physicists think these are more far-fetched than the indeterministic interpretations.

[ QUOTE ]
Is it safe to say, then, that inherent randomness of the universe has not been *proven* (at least to the extent that something can be proven in physics), even though it is widely (but not unanimously) believed among leading physicists?

[/ QUOTE ]
Yes.

By the way, neither determinism nor indeterminism can ever be completely established. Where the universe looks random, it's always possible that there's an underlying pattern we just haven't discovered yet. Where the universe looks deterministic, it's always possible that the apparent pattern is accounted for merely by a series of (huge) coincidences.

[Darryl_P]

I wish I had a nickel for every time I've heard an atheist say to a theist "why can't you accept that it's just random?"

These guys think that's the end of the line. Something is random, here's the distribution, so we've explained it, end of story. If that's not ultimacy then I don't know what is.

Anyway, I thought it was agnostics who don't make any bold claims.

[ QUOTE ]
Anyway, I thought it was agnostics who don't make any bold claims.

[/ QUOTE ]

thought wrong

http://en.wikipedia.org/wiki/Atheist

[atrifix]

In the philosophical world, "weak atheism" is usually referred to as agnositicism, and "strong atheism" is usually just referred to as atheism. These are typically beliefs about an omnipotent, omniscient, omnibenevolent god, not just any gods in general.

[chezlaw]

[ QUOTE ]
Where I think you go wrong is in saying that there's something deterministic going on in the measurement process. While you could be right, there's no evidence to support this, and QM works just fine without it.

[/ QUOTE ]
I just wanted to see if it worked, I'm not making the mistake of saying something deterministic is going on, just that it could be and hence Bells work cannot prove that there are random events. [My main interest is that it gives me a way of thinking about QM that is reasonably intuitive]

QM looks so like late evaluation to me, which is independent of the determinism issue, that I don't see how QM could convince someone either way. Moving away from the computer analogy, it seems intuitive that as there is no use in evaluating states that are never used, any efficient universe should work this way.

The OP may notice he has now got the result he was after in the first place, although that's definitely not what motivates my interest.

Thanks for your help.

chez

[kevyk]

Here's the thought experiment that Bohm proposed:

Two entangled electrons (spin adds to zero) set off in opposite directions. At distance d to the right, electron 1 passes through a Stern-Gerlach magnet which is oriented to measure the spin as "up" or "down." It measures the spin of electron 1 to be "up." At distance 2*d to the left, electron 2 passes through another Stern-Gerlach magnet, which is oriented to measure a "right" or "left" spin. It measures the spin to be "right."

A "realist" looking at the first measurement would conclude that electron 2's "actual" spin was "down." The same experimenter looking at the second measurement would conclude that electron 1's "actual" spin was "left."

The point is that if each electron has an acutal, but unknowable spin, this result should not be possible. Yet, it is what actually happens when the experiment is conducted, and is the result predicted by the classical quantum theory. An electron's spin choice with repect to a given axis seems to be genuinely indeterminate before a measurement is made.

Of course, I will make the disclaimer that there are non-local hidden-variable theories which have not been ruled out--but the smart money seems to be on genuine randomness.

[Darryl_P]

[ QUOTE ]
Of course, I will make the disclaimer that there are non-local hidden-variable theories which have not been ruled out--but the smart money seems to be on genuine randomness.

[/ QUOTE ]

Are these non-local hidden-variable theories the ONLY ones that exclude true randomness or would the MWI accomplish it also? Or is the MWI a hidden-variable theory?

Philosophically speaking I don't see how the idea of the observer influencing the event being observed (which I have no trouble accepting) is incompatible with determinism. Or is there a reason why I should?

[chezlaw]

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Of course, I will make the disclaimer that there are non-local hidden-variable theories which have not been ruled out--but the smart money seems to be on genuine randomness.

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Would the computer simulation idea be a hidden-value theory?

I thought not, in which case hidden-value or genuine randomness are not the only options.

chez

[Trantor]

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Of course, I will make the disclaimer that there are non-local hidden-variable theories which have not been ruled out--but the smart money seems to be on genuine randomness.

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Are these non-local hidden-variable theories the ONLY ones that exclude true randomness or would the MWI accomplish it also? Or is the MWI a hidden-variable theory?

Philosophically speaking I don't see how the idea of the observer influencing the event being observed (which I have no trouble accepting) is incompatible with determinism. Or is there a reason why I should?

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WMI is not predicated on any hidden variable theory.

Observations (measurements) affecting the state of the system being measured (in a quantum measurement sense) is not incompatible with determinism....that is hidden variable theory, for example (which I'm not aware has been proved to be impossible but which most scientists in the field believe is wrong). Determinism in the sense that some (all?)probabalistic events of QM have a non-random mechanism that means they are non-probabilistic, in fact.

[Cyrus]

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When did you last see an atom?

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MMMMMM showed me his brainscan once.

Huge magnification.

[Trantor]

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I wish I had a nickel for every time I've heard an atheist say to a theist "why can't you accept that it's just random?"

These guys think that's the end of the line. Something is random, here's the distribution, so we've explained it, end of story. If that's not ultimacy then I don't know what is.

Anyway, I thought it was agnostics who don't make any bold claims.

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It's apparantly random because all science points that way. christian and atheist physicists all agree (except for the view trying to devise a hidden variable theory for example). religion has absolutely nothing to do with it, any more than religion should have had anything to do with the fact or fiction of the earth going round the sun!

[Darryl_P]

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christian and atheist physicists all agree (except for the view trying to devise a hidden variable theory for example).

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How about those who ascribe to the many-worlds interpretation as opposed to the Copenhagen interpretation? As I understand these are no insignificant fringe group.