My friend talks Quantum...

[-Fran-]

I started a thread about this in the general woo forum, but someone pointed out that there will maybe be more people here who can answer my questions, so I will try here as well. A friend of mine sent me this as a part of an on-going discussion via mail (my translation) and I feel it is not quite right, but lack the knowledge to reply in a good way.

No no no! There is no objective reality. That's an illusion and a model that can no longer explain the universe. These ideas are called Quantum Physics and are soon a 100 years old. Niels Bohr explain with the Copenhagen Interpretation (yeah, you can google that) that we have an effect on what we study. The thing is that the quantum level is so tiny that it obeys completely different laws than our "reality" but they are still what builds our universe (as particles or waves, not both at the same time). Why not both at the same time? Because we have something that is called The Observer Effect (yeah you can google that). You see what you expect to see. That is science that has been proven empirically. The old philosophical question about if the tree that falls in the wood can be heard if noone is there to listen gets a totally new meaning in Quantum Physics. According to Quantum Phsyics there isn't even a tree then...

These are the questions I want to ask about these claims (though there are sure more that can be asked):

Is saying there is no objective reality with such certainty an extraordinary claim?

Is the Copenhagen Interpretation completely accepted by all of science, or are there others?

The thing is that the quantum level is so tiny that it obeys completely different laws than our "reality" but they are still what builds our universe

He seems to claim that reality does not then obey different laws after all since it is made up of the particles that does obey different laws = our reality is an illusion, and only seem to be what it is because of the observer effect. Is there something to it, or does he misunderstand what science says about QM? I am really not sure what he actually tries to claim here

Does the observer effect have anything at all to do with how humans interact with the world around them on a macro scale?

What the *bleep* has the fallen tree to do with it all?

Can anyone help me straighten this out?

 

[sol invictus]

Is saying there is no objective reality with such certainty an extraordinary claim?

Quantum mechanics is a precise mathematical theory about the world. If quantum mechanics is correct (which it almost certainly is), it tells us what objective reality is and the claim is false (in fact it's the opposite of the truth).

Is the Copenhagen Interpretation completely accepted by all of science, or are there others?

Yes - the CI is not even the interpretation most widely accepted by physicists. But regardless, your friend's statements about it are wrong. For example, "You see what you expect to see" - that sounds like he has confused "expectation value", a technical term in QM, with "expect" in the common sense. In any case the statement is false.

He seems to claim that reality does not then obey different laws after all since it is made up of the particles that does obey different laws = our reality is an illusion, and only seem to be what it is because of the observer effect. Is there something to it, or does he misunderstand what science says about QM? I am really not sure what he actually tries to claim here

It is certainly the case that the laws of QM are "weird" and non-intuitive. The laws of physics as they apply to macroscopic, human sized objects are relatively easy to understand, because they correspond to our ordinary experience. The laws of physics as they apply to electrons are not. But there is only one set of laws - it's just that they behave qualitatively differently in different regimes.

Does the observer effect have anything at all to do with how humans interact with the world around them on a macro scale?

Calling it an "observer" effect is misleading. It doesn't make any difference to the physics whether the thing doing the "observing" is a human being, a dog, a robot, or a rock. When a large system interacts with a small system, the wavefunction of the small system collapses. The only requisite feature of the system is that it be large, not that it be an "observer".

 

[Philippe Leick]

I am really not sure what he actually tries to claim here

Neither am I, but I'll try to help anyway. Of course, the question of whether there is an objective reality is more of a philosophical than a scientific one. But there certainly isn't any contradiction between quantum mechanics and objective reality.

Is saying there is no objective reality with such certainty an extraordinary claim?

Yes. Defintely yes. Quantum Mechanics (QM) says no such thing. There's an underlying reality, which some people may think of as strange or counterintuitive, but it is still an objective, quantum reality.

Is the Copenhagen Interpretation completely accepted by all of science, or are there others?

No, although Copenhagen is still popular, there are others. Anyway, the Copenhagen Interpretation isn't what your friend claims it to be. Also, the interpretations of QM aren't all that important, since they all make the same claims about phenomena that can be observed. You can think of it this way: they differ according to what is supposed to happen "behind the curtain".

Does the observer effect have anything at all to do with how humans interact with the world around them on a macro scale?

No... at least, not really. To make things clear: there is a "quantum observer effect", irrelevant for everyday life, which can be simplified thus: quantum systems (electrons, for example) interact with the devices used to measure their behavior. They may behave differently, depending on the measurement devices used. The effect can be significant, since quantum systems are generally quite small, and measurement devices can be rather large.
You could also say that there's an everyday observer effect: "measurements" can influence the system being measured. Just think of crash tests being done to test the safety of new car models... The car isn't the same after the measurement. Nothing special about that, but not exactly the quantum "observer effect".

Keep in mind that the quantum "observer effect" has everything to do with the devices used to measure the properties of the system, and with the system itself, but absolutely nothing to do with the consciousness of the researchers!

What the *bleep* has the fallen tree to do with it all?

That's rather complicated to answer, but again, your friend's got it wrong ("According to Quantum Physics there isn't even a tree then..."). First, the quantum effects he's misunderstood don't apply to trees. Second, if they did (which they don't!), the tree would be in some indeterminate state: "fallen/not fallen". Only a measurememt can tell us whether it's actually fallen or not. But since a tree is a large, complex object, it's interacting all the time with it's surroundings, which is kind of like being constantly measured. Which, in a nutshell, is one of the reasons that the tree is an everyday and not a quantum object.
And even quantum objects obey some natural laws (quantum mechanics), which certainly don't say that "everything goes". For example, they can't just disappear when nobody's looking. They can only hide

Hope this helps. I'll try to check back if you post some more questions.

 

[Philippe Leick]

When a large system interacts with a small system, the wavefunction of the small system collapses.

So you are a proponent of the Copenhagen interpretation, Sol Invictus

Your comments are also spot on.

 

[shadron]

As a supplement to Sol's (and now I see also Phillippe's - Hello, and welcome, Phillippe) statement, the wiki article on the Copenhagen Interpretation says:

Alternatives

The Ensemble Interpretation is similar; it offers an interpretation of the wave function, but not for single particles. The consistent histories interpretation advertises itself as "Copenhagen done right". Consciousness causes collapse is often confused with the Copenhagen interpretation.
If the wave function is regarded as ontologically real, and collapse is entirely rejected, a many worlds theory results. If wave function collapse is regarded as ontologically real as well, an objective collapse theory is obtained. Dropping the principle that the wave function is a complete description results in a hidden variable theory.
Many physicists have subscribed to the null interpretation of quantum mechanics summarized by the sentence "Shut up and calculate!". While it is sometimes attributed to Paul Dirac[15] or Richard Feynman, it is in fact due to David Mermin[16].

A list of alternatives can be found at Interpretation of quantum mechanics.



...


According to a poll at a Quantum Mechanics workshop in 1997, the Copenhagen interpretation is the most widely-accepted specific interpretation of quantum mechanics, followed by the many-worlds interpretation.[7] Although current trends show substantial competition from alternative interpretations, throughout much of the twentieth century the Copenhagen interpretation had strong acceptance among physicists. Astrophysicist and science writer John Gribbin describes it as having fallen from primacy after the 1980s.

If I knew enough to know, I'd subscribe to the SU&C interpretation, just because it sounds skeptical . The many-worlds idea is a favorite of science fiction, as it yields lots of richness for time-travel and alternate universes.

Alternatives

The Ensemble Interpretation is similar; it offers an interpretation of the wave function, but not for single particles. The consistent histories interpretation advertises itself as "Copenhagen done right". Consciousness causes collapse is often confused with the Copenhagen interpretation.
If the wave function is regarded as ontologically real, and collapse is entirely rejected, a many worlds theory results. If wave function collapse is regarded as ontologically real as well, an objective collapse theory is obtained. Dropping the principle that the wave function is a complete description results in a hidden variable theory.
Many physicists have subscribed to the null interpretation of quantum mechanics summarized by the sentence "Shut up and calculate!". While it is sometimes attributed to Paul Dirac[15] or Richard Feynman, it is in fact due to David Mermin[16].

A list of alternatives can be found at Interpretation of quantum mechanics.



...


According to a poll at a Quantum Mechanics workshop in 1997, the Copenhagen interpretation is the most widely-accepted specific interpretation of quantum mechanics, followed by the many-worlds interpretation.[7] Although current trends show substantial competition from alternative interpretations, throughout much of the twentieth century the Copenhagen interpretation had strong acceptance among physicists. Astrophysicist and science writer John Gribbin describes it as having fallen from primacy after the 1980s.

If I knew enough to know, I'd subscribe to the SU&C interpretation, just because it sounds skeptical . The many-worlds idea is a favorite of science fiction, as it yields lots of richness for time-travel and alternate universes." target="_blank">WP

 

[sol invictus]

Your comments are also spot on.

Thanks, yours too, and welcome.

So you are a proponent of the Copenhagen interpretation, Sol Invictus

My wavefunction has long since peaked and decohered along the Everett interpretation.

I used collapse as a shorthand - what really happens in a spin measurement is that the total wavefunction "collapses" to a state where it is peaked sharply along both possibilities (spin is x and measuring device reads x plus spin is y and measuring device reads y).

 

[-Fran-]

Quantum mechanics is a precise mathematical theory about the world. If quantum mechanics is correct (which it almost certainly is), it tells us what objective reality is and the claim is false (in fact it's the opposite of the truth).



Yes - the CI is not even the interpretation most widely accepted by physicists. But regardless, your friend's statements about it are wrong. For example, "You see what you expect to see" - that sounds like he has confused "expectation value", a technical term in QM, with "expect" in the common sense. In any case the statement is false.



It is certainly the case that the laws of QM are "weird" and non-intuitive. The laws of physics as they apply to macroscopic, human sized objects are relatively easy to understand, because they correspond to our ordinary experience. The laws of physics as they apply to electrons are not. But there is only one set of laws - it's just that they behave qualitatively differently in different regimes.



Calling it an "observer" effect is misleading. It doesn't make any difference to the physics whether the thing doing the "observing" is a human being, a dog, a robot, or a rock. When a large system interacts with a small system, the wavefunction of the small system collapses. The only requisite feature of the system is that it be large, not that it be an "observer".

Thanks for these explanations!! I brought these things up in a reply for him. I wrote a quite lengthy reply, and I am sure I probably messed up something in there, but I think I might at least have got the very basics down on why what he said is not quite right. I have not got any reply from him yet though.

 

[-Fran-]

Neither am I, but I'll try to help anyway. Of course, the question of whether there is an objective reality is more of a philosophical than a scientific one. But there certainly isn't any contradiction between quantum mechanics and objective reality.


Yes. Defintely yes. Quantum Mechanics (QM) says no such thing. There's an underlying reality, which some people may think of as strange or counterintuitive, but it is still an objective, quantum reality.


No, although Copenhagen is still popular, there are others. Anyway, the Copenhagen Interpretation isn't what your friend claims it to be. Also, the interpretations of QM aren't all that important, since they all make the same claims about phenomena that can be observed. You can think of it this way: they differ according to what is supposed to happen "behind the curtain".


No... at least, not really. To make things clear: there is a "quantum observer effect", irrelevant for everyday life, which can be simplified thus: quantum systems (electrons, for example) interact with the devices used to measure their behavior. They may behave differently, depending on the measurement devices used. The effect can be significant, since quantum systems are generally quite small, and measurement devices can be rather large.
You could also say that there's an everyday observer effect: "measurements" can influence the system being measured. Just think of crash tests being done to test the safety of new car models... The car isn't the same after the measurement. Nothing special about that, but not exactly the quantum "observer effect".

Keep in mind that the quantum "observer effect" has everything to do with the devices used to measure the properties of the system, and with the system itself, but absolutely nothing to do with the consciousness of the researchers!


That's rather complicated to answer, but again, your friend's got it wrong ("According to Quantum Physics there isn't even a tree then..."). First, the quantum effects he's misunderstood don't apply to trees. Second, if they did (which they don't!), the tree would be in some indeterminate state: "fallen/not fallen". Only a measurememt can tell us whether it's actually fallen or not. But since a tree is a large, complex object, it's interacting all the time with it's surroundings, which is kind of like being constantly measured. Which, in a nutshell, is one of the reasons that the tree is an everyday and not a quantum object.

And even quantum objects obey some natural laws (quantum mechanics), which certainly don't say that "everything goes". For example, they can't just disappear when nobody's looking. They can only hide

The little rascals

Hope this helps. I'll try to check back if you post some more questions.

Thanks!! This was big help and I managed to compose a rather lenghty reply to him. As I said above in a comment, I am not sure I managed to get all of it right, after all I don't claim to actually understand QM, and I told him that too. But I hope I managed to get it enough clear that neither does he... I've got no answer from him yet though, I was being nice, but maybe he got miffed with me anyway, well... If he do reply I might come back with more questions, depending on what he says, if it's all right?

 

[-Fran-]

As a supplement to Sol's (and now I see also Phillippe's - Hello, and welcome, Phillippe) statement, the wiki article on the Copenhagen Interpretation says:



If I knew enough to know, I'd subscribe to the SU&C interpretation, just because it sounds skeptical . The many-worlds idea is a favorite of science fiction, as it yields lots of richness for time-travel and alternate universes. ^{. The many-worlds idea is a favorite of science fiction, as it yields lots of richness for time-travel and alternate universes." target="_blank">WP}

Thanks! I brought this up too in a reply to him.^WP