I Quantum mechanics is random in nature?

[entropy1]

So, I take it the formalism leaves room for a deterministic as well as a strictly random interpretation. My take on that is that you can't get strict randomness from determinism, but you can get determinism overlaying strict randomness (in the formalism at least). So randomness is the more fundamental factor in my view. My preference goes to strict randomness. However, the formalism leaves it open to interpretation.

 

[Zafa Pi]

"Individual events resulting from identical preparations are not reproducible. ...
Whether this nonreducibility is due to nondeterminism in nature, or merely to limitations (practical or fundamental) in the preparation procedure, is a question we cannot, and need not, answer here. The statistical approach is applicable in any case." Ballentine, page 44. (My emphasis)

Randomness (undefined), intrinsic?, lack of knowledge?, unknown algorithm?, which is the fairest of them all? I won't tell, I can't tell, and neither will the great John Bell.
Keep chasing fairies, ladies and gentlemen, it's good exercise.

 

[Jilang]

Well, the first part of your question is a matter of interpretation, the answer would be yes in MWI and no in BM.
The second part I guess is also yes, except of course a brick will serve just as well.
If an atom decays somewhere in the interstellar space far away from everything else, then, until the pieces actually hit something else (and it may take a while), it exists in superposition of decayed and non-decayed. When an atom or a decay product collides with another particle it gets entangled with it. It still remains in superposition but now it involves another atom as well. Eventually the number of other particles involved becomes sufficiently large for the process to be irreversible but it will take much longer. (well, that is how I understand it)

It's an interesting idea, but how likely is it that pieces flying apart would spontaneously recombine?

 

[davenn]

It's an interesting idea, but how likely is it that pieces flying apart would spontaneously recombine?

depends on the particles
eg ...
for alpha particle decay, very easily ... The alpha particle is just a helium nucleus and with readily recombine with free electrons
to form a stable Helium atom

 

[Zafa Pi]

depends on the particles
eg ...
for alpha particle decay, very easily ... The alpha particle is just a helium nucleus and with readily recombine with free electrons
to form a stable Helium atom

I thought that alpha and beta decay refer to atom that undergoes radioactive decay by emitting an alpha particle or an electron. The alpha particles and electrons themselves are not decaying.

 

[atyy]

A Geiger counter counts decays and not "non-decays". The Geiger counter doesn't cause the decay but registers it. Maybe I don't understand the question right, but isn't this obvious?

How can you show that the Geiger counter does not cause the decay?

Above you claimed that philosophical speculations are irrelevant for physics. Why is it relevant for physics that the Geiger counter caused or did not cause the decay? If you cannot show that the Geiger counter does not cause the decay, then it is you that is promoting the irrelevant philosophical speculations.

 

[davenn]

I thought that alpha and beta decay refer to atom that undergoes radioactive decay by emitting an alpha particle or an electron. The alpha particles and electrons themselves are not decaying.

yes that's correct, and I didn't state anything to the contrary,
but that wasn't the comment/question I was answering

 

[davenn]

How can you show that the Geiger counter does not cause the decay?

I counter that with ... can you show us that it does ??

I agree with vanhees71 ... the counter is just reacting/detecting particle emission

 

[DrChinese]

How can you show that the Geiger counter does not cause the decay?

There are plenty of ways to demonstrate this. For example, the number of clicks increases in the presence of radioactive material, but is absent when there is no such material nearby.

Your comments have veered well off the thread subject.

 

[atyy]

I counter that with ... can you show us that it does ??

I agree with vanhees71 ... the counter is just reacting/detecting particle emission

That is not a counter, since I never claimed (in the minimal interpretation) that it does. In the minimal interpretation, whether it does or does not is irrelevant.

 

[atyy]

There are plenty of ways to demonstrate this. For example, the number of clicks increases in the presence of radioactive material, but is absent when there is no such material nearby.

Your comments have veered well off the thread subject.

And do decays occur when there is no Geiger counter to register them?

 

[vanhees71]

How can you show that the Geiger counter does not cause the decay?

Above you claimed that philosophical speculations are irrelevant for physics. Why is it relevant for physics that the Geiger counter caused or did not cause the decay? If you cannot show that the Geiger counter does not cause the decay, then it is you that is promoting the irrelevant philosophical speculations.

If the observation would cause a radioactive substance to decay, it wouldn't decay, if nobody is "looking". This is obviously not true according to observations, because fortunately radioactive substances decay, no matter whether you look at them, and it's pretty hard to prevent it from decaying (there are examples like bound beta decay, where the Pauli principle has dramatic effects, but that's not the point here).

 

[atyy]

If the observation would cause a radioactive substance to decay, it wouldn't decay, if nobody is "looking". This is obviously not true according to observations, because fortunately radioactive substances decay, no matter whether you look at them, and it's pretty hard to prevent it from decaying (there are examples like bound beta decay, where the Pauli principle has dramatic effects, but that's not the point here).

But this seems to lead to the conclusion that the moon is there when nobody is looking!

 

[vanhees71]

Well, several conservation laws tell you that the moon is there when nobody is looking. This is one of those pseudoproblems you can think about if you are a philosopher ;-)).

 

[DrChinese]

And do decays occur when there is no Geiger counter to register them?

This question has nothing whatsoever to do with quantum mechanics. You may as well ask if rocks stick to the Earth when there is no scale to weigh them.

 

[atyy]

Well, several conservation laws tell you that the moon is there when nobody is looking. This is one of those pseudoproblems you can think about if you are a philosopher ;-)).

So particles have trajectories?

 

[atyy]

This question has nothing whatsoever to do with quantum mechanics. You may as well ask if rocks stick to the Earth when there is no scale to weigh them.

Do they?

The question is intinmately related to quantum mechanics. The usual answer is that in the minimal interpretation, quantum mechanics is silent on such issues. If we are also silent on such issues, then quantum mechanics is random - that is one version of Bell's theorem.

If the moon is there when we are not looking, then Bell's theorem says nothing about whether quantum mechanics is fundamentally random.

 

[vanhees71]

So particles have trajectories?

How do you come to this conclusion?

 

[DrChinese]

Do they?

The question is intinmately related to quantum mechanics. The usual answer is that in the minimal interpretation, quantum mechanics is silent on such issues. If we are also silent on such issues, then quantum mechanics is random - that is one version of Bell's theorem.

If the moon is there when we are not looking, then Bell's theorem says nothing about whether quantum mechanics is fundamentally random.

That you ask "do they" shows that this discussion has veered away from quantum mechanics.

To the question of whether a Geiger counter is the cause of atomic decay, the answer is: of what relevance is the answer to observed randomness of quantum behavior?

Bell says nothing about whether quantum mechanics is fundamentally random regardless of whether particles have observable attributes when not observed.

 

[vanhees71]

It's utter nonsense! No matter if you put a counter somewhere in Chernobyl radioactive elements decay according to their half-life. You can measure today and then take away the counter and measure again in 10 years at the same place. Then you'll see that the stuff decayed, no matter whether your counter was there or not.

 

[atyy]

That you ask "do they" shows that this discussion has veered away from quantum mechanics.

To the question of whether a Geiger counter is the cause of atomic decay, the answer is: of what relevance is the answer to observed randomness of quantum behavior?

The answer is relevant to the randomness of quantum behaviour.

If we are agnostic about whether the moon is there when we are not looking, we are taking an operational view of quantum mechanics. Under the operational view, assuming signal locality, Bell's theorem guarantees operational randomness.

But if the moon is there when we are not looking, then we are assuming reality. Assuming reality, Bell's theorem guarantees nonlocality.

Thus the answer to the question in the OP depends intimately on how we answer the question as to whether the moon is there when we are not looking.

 

[vanhees71]

Also in quantum theory there are conservation laws telling you that the moon doesn't vanish, only because nobody is looking at her. This is now REALLY and empty discussion. Bell used this example to ridicule the collapse idea. He's also asking whether you need a "conscious observer", and what that might mean. Has there be the first collapse, when human beings made an observation or is an amoeba, making an observation enough?

 

[Grinkle]

Thus the answer to the question in the OP depends intimately on how we answer the question as to whether the moon is there when we are not looking.

In what sense is it practical to not look? To look means to interact with some other particle. It doesn't mean to look in the animal sense and to comprehend.

 

[vanhees71]

When I look at the moon my eyes just detect light that's reflected by the moon no matter whether I look at her or not.

 

[atyy]

How do you come to this conclusion?

If the moon is always there, then a particle is always there too. That means a particle has a trajectory.

 

[DrChinese]

Assuming reality, Bell's theorem guarantees nonlocality.

Your premise is flawed. There is no element of Bell's Theorem that says: IF realism, THEN non-locality. Nor does it imply: IF non-locality, THEN not realism.

Bell implies (assuming QM is correct): Realism and locality cannot BOTH be correct. (It is not "one or the other", although that is possible. BOTH may be bad assumptions.)

Even in Bohmian Mechanics, where the idea is that there are root causes for quantum behavior: true randomness cannot be ruled out. There is just too much unknown to make a firm statement about that point. How would you ever tell the difference?

 

[atyy]

In what sense is it practical to not look? To look means to interact with some other particle. It doesn't mean to look in the animal sense and to comprehend.

The observer is privileged in quantum mechanics, and so to look is subjective, not an objective interaction with some other particle.

 

[atyy]

Your premise is flawed. There is no element of Bell's Theorem that says: IF realism, THEN non-locality. Nor does it imply: IF non-locality, THEN not realism.

Bell implies (assuming QM is correct): Realism and locality cannot BOTH be correct. (It is not "one or the other", although that is possible. BOTH may be bad assumptions.)

Even in Bohmian Mechanics, where the idea is that there are root causes for quantum behavior: true randomness cannot be ruled out. There is just too much unknown to make a firm statement about that point. How would you ever tell the difference?

You are missing my big point - Bell's theorem guarantees randomness under the operational view of quantum mechanics.

 

[vanhees71]

If the moon is always there, then a particle is always there too. That means a particle has a trajectory.

Come on! This is really an ageold discussion answered by modern QT clearly being wrong. You have only probability distributions for position and momentum!

 

[DrChinese]

You are missing my big point - Bell's theorem guarantees randomness under the operational view of quantum mechanics.

No, it doesn't. It is silent on that point, and I can't imagine what relevance that is to this thread. It is only INTERPRETATIONS of QM that have anything to say about randomness.

 

[atyy]

Come on! This is really an ageold discussion answered by modern QT clearly being wrong. You have only probability distributions for position and momentum!

You cannot have simultaneous canonically conjugate position and momentum, but that does not rule out a trajectory. A person who says the moon is there when he is not looking at it is a closet Bohmian.

 

[atyy]

No, it doesn't. It is silent on that point, and I can't imagine what relevance that is to this thread. It is only INTERPRETATIONS of QM that have anything to say about randomness.

No it really does! That's one of the main points about Bell's theorem - under the operational view, it guarantees randomness - and randomness is the subject of this thread.

 

[vanhees71]

What has Bohmian mechanics to do with that? I think, we should stop the discussion here. I admit, I shouldn't have gotten involved again.

 

[atyy]

Here is how Bell's theorem can guarantee randomness https://arxiv.org/abs/0911.3427

 

[DrChinese]

Here is how Bell's theorem can guarantee randomness https://arxiv.org/abs/0911.3427

Sorry, that reference has nothing to do with your assertion (beyond a casual reading of the title). I would challenge you to provide a suitable source that says that Bell's Theorem guarantees the world is - or is not - random. Short of that, it is time for you to drop this line, as it represents personal speculation on your part.

It is clear that any Bohmian would assert that Bohmian mechanics is viable and explains randomness in observations. Whether you agree with that or not, it is also clear that all suitable observations of quantum behavior demonstrate what appears to be random behavior. So we gain nothing past this.

 

[atyy]

Sorry, that reference has nothing to do with your assertion (beyond a casual reading of the title). I would challenge you to provide a suitable source that says that Bell's Theorem guarantees the world is - or is not - random. Short of that, it is time for you to drop this line, as it represents personal speculation on your part.

It is a theorem, not my personal speculation.

 

[DrChinese]

It is a theorem, not my personal speculation.

Please: what is that theorem and where is it published in peer reviewed literature?

 

[atyy]

Please: what is that theorem and where is it published in peer reviewed literature?

Read the reference. And stop distorting what I am saying.

 

[DrChinese]

1. Read the reference.

2. And stop distorting what I am saying.

1. The reference is unsuitable, and saying "read it" is ridiculous when you can quote whatever you think supports your assertion.

Other theorems are other theorems. Really not much to discuss about that. And there are no other theorems, the reference included, that proves whether there is or is not randomness in nature. What we have to tell us about that is observation, which clearly supports randomness in nature. But there are counter-interpretations that are viable.

If you will not support your assertions with suitable references, you can probably predict the next appropriate step. Your line of reasoning has derailed meaningful discussion of this topic.2. You are stating your position clearly, and it is incorrect. Bell is silent about the role of randomness in quantum mechanics. There is nothing in the accepted literature that says otherwise.

 

[atyy]

1. The reference is unsuitable, and saying "read it" is ridiculous when you can quote whatever you think supports your assertion.

Other theorems are other theorems. Really not much to discuss about that. And there are no other theorems, the reference included, that proves whether there is or is not randomness in nature. What we have to tell us about that is observation, which clearly supports randomness in nature. But there are counter-interpretations that are viable.

If you will not support your assertions with suitable references, you can probably predict the next appropriate step. Your line of reasoning has derailed meaningful discussion of this topic.2. You are stating your position clearly, and it is incorrect. Bell is silent about the role of randomness in quantum mechanics. There is nothing in the accepted literature that says otherwise.

Stop distorting my position! I have said that if we take the operational view of quantum mechanics, Bell's theorem does guarantee randomness.

The reference I provided is suitable.

 

[Drakkith]

Thread locked, pending moderation.