Jump to content
Elite Engineer

Is "Schrodinger's Cat" the wrong interpretation for Copenhagen Interpretation?

Recommended Posts

1 hour ago, Bender said:

Why should there be only one that is different? 

It's offered as a superposition of states.

Share this post


Link to post
Share on other sites

I'm not sure where you are going with this, so I'll guess. What about the baryon number of the radioactive isotope used?

Share this post


Link to post
Share on other sites
2 minutes ago, Bender said:

I'm not sure where you are going with this, so I'll guess. What about the baryon number of the radioactive isotope used?

Well I'm completely flummoxed with this so that makes two of us.

:)

What about it?

Share this post


Link to post
Share on other sites
10 minutes ago, studiot said:

Well I'm completely flummoxed with this so that makes two of us.

:)

What about it?

You asked for one quantum number that is different between the two humongous groups of quantum states describing dead of living cats. I provided one.

Still not sure what you want with it. :)

Share this post


Link to post
Share on other sites
1 hour ago, swansont said:

It's offered as a superposition of states.

Does that mean that it has to be only one state? I had assumed that the superposition of a live cat and a dead cat would involve a huge number of superposed states. And that was one reason for the implausibility of the scenario.

Share this post


Link to post
Share on other sites
3 minutes ago, Bender said:

What about it?

What about it means show me a calculation to determine that it is different.

Share this post


Link to post
Share on other sites

Suppose eg Radon 210 is used, which decays to Polonium 206. In the states with a living cat, the baryon number is 210. In the states with a dead cat, the baryon number is 206.

Share this post


Link to post
Share on other sites
17 minutes ago, Bender said:

Suppose eg Radon 210 is used, which decays to Polonium 206. In the states with a living cat, the baryon number is 210. In the states with a dead cat, the baryon number is 206.

How does that involve the uncertainty principle?

Share this post


Link to post
Share on other sites
2 minutes ago, studiot said:

How does that involve the uncertainty principle?

I thought this was about superposition?

Share this post


Link to post
Share on other sites
2 minutes ago, Strange said:

I thought this was about superposition?

Well the title of this thread quotes Schroedinger's cat, which is a proposition about applying the HUP in the situation described.

The so called Copenhagen Interpretation offers the superposition.

 

There does seem to be some misunderstanding about superposition and I am suprised at Bender since the meaning is the same as in Engineeering, where I feel sure he is familiar with it.

Another name for it is simultaneous equations.

Share this post


Link to post
Share on other sites
5 minutes ago, studiot said:

How does that involve the uncertainty principle?

How doesn't it?

I have the impression you want to get to some point, but I don't know what that point might be. 

Share this post


Link to post
Share on other sites
2 minutes ago, studiot said:

Well the title of this thread quotes Schroedinger's cat, which is a proposition about applying the HUP in the situation described.

I can't see how HUP applies to Schroedinger's Cat:

"The scenario presents a cat that may be simultaneously both alive and dead,[2][3][4][5][6][7][8] a state known as a quantum superposition, as a result of being linked to a random subatomic event that may or may not occur. "

https://en.wikipedia.org/wiki/Schrödinger's_cat

There is no mention of the uncertainty principle in that article. Can you explain how it is relevant?

Share this post


Link to post
Share on other sites
1 hour ago, Strange said:

Does that mean that it has to be only one state? I had assumed that the superposition of a live cat and a dead cat would involve a huge number of superposed states. And that was one reason for the implausibility of the scenario.

I don't know how the quantum state of an atom correlates with a live or dead cat.

48 minutes ago, Bender said:

Suppose eg Radon 210 is used, which decays to Polonium 206. In the states with a living cat, the baryon number is 210. In the states with a dead cat, the baryon number is 206.

Not sure what that has to do with a quantum state.

23 minutes ago, studiot said:

Well the title of this thread quotes Schroedinger's cat, which is a proposition about applying the HUP in the situation described.

No, not the HUP.

Share this post


Link to post
Share on other sites

Just so we are all discussing the same thing...

When a quantum particle is not being observed/detected, it is described by a wave function.
The wave function is a 'complex valued probability amplitude' encoding all possible states ( position, momentum, spin, etc. ), such that the probability of observing any given state ( upon detection and collapse of the wave function ) is the absolute value of the square.
And those probabilities must add up to 1.
Because of this, two valid wave functions can be added to produce a similarly valid wave function.
 

Considering the fact that an observation/detection is simply an interaction ( collision with Phosphor on a screen, for example ), I find it hard to believe that all of the billion, billion, billion atoms of a cat can avoid interacting, and stay in the 'superpositioned' indeterminate state such that the whole cat is in an indeterminate state of superposition.
Not alive or dead; those aren't valid degrees of freedom.

( and I don't see a relation to HUP either )

 

Share this post


Link to post
Share on other sites
6 hours ago, studiot said:

There does seem to be some misunderstanding about superposition and I am suprised at Bender since the meaning is the same as in Engineeering, where I feel sure he is familiar with it.

If it is wave functions you want, I'm afraid I have no formal education in QM and not familiar enough with the mathematics to write down the wave function of multi-particle systems, such as a decaying isotope.

 

6 hours ago, swansont said:

Not sure what that has to do with a quantum state.

The experiment usually involves a decaying isotope to determine the fate of the cat. In a decaying isotope the alpha particle is either inside or outside the nucleus.

 

3 hours ago, MigL said:

Just so we are all discussing the same thing...

When a quantum particle is not being observed/detected, it is described by a wave function.
The wave function is a 'complex valued probability amplitude' encoding all possible states ( position, momentum, spin, etc. ), such that the probability of observing any given state ( upon detection and collapse of the wave function ) is the absolute value of the square.
And those probabilities must add up to 1.
Because of this, two valid wave functions can be added to produce a similarly valid wave function.
 

Considering the fact that an observation/detection is simply an interaction ( collision with Phosphor on a screen, for example ), I find it hard to believe that all of the billion, billion, billion atoms of a cat can avoid interacting, and stay in the 'superpositioned' indeterminate state such that the whole cat is in an indeterminate state of superposition.
Not alive or dead; those aren't valid degrees of freedom.

( and I don't see a relation to HUP either )

 

Obviously, interaction is not a sufficient criterion for collapse, as is evidenced by two slit experiments with molecules or entanglement of phonons (where billion billion billion atoms interact in a crystal lattice)

Besides, there is no evidence that wave functions actually collapse. It could be no more than a mathematical construct.

Share this post


Link to post
Share on other sites
5 hours ago, Bender said:

 The experiment usually involves a decaying isotope to determine the fate of the cat. In a decaying isotope the alpha particle is either inside or outside the nucleus.

That's to give you a random event to put the cat into the superposition, since whether or not the decay has occurred decides whether you've killed the cat. 

5 hours ago, Bender said:

 Obviously, interaction is not a sufficient criterion for collapse, as is evidenced by two slit experiments with molecules or entanglement of phonons (where billion billion billion atoms interact in a crystal lattice)

The phonons are entangled, not the atoms. The atoms interacting is not the issue. It has to be an interaction with the quantum states in question.

5 hours ago, Bender said:

Besides, there is no evidence that wave functions actually collapse. It could be no more than a mathematical construct.

Wave functions are a mathematical construct. 

Share this post


Link to post
Share on other sites

https://en.wikipedia.org/wiki/Schrödinger's_cat

Quantum mechanics is founded on uncertainty principle. It seemed to me a while ago that there seems to be two sorts of uncertainty here.

(1) Uncertainty caused by limitations in technology available to measure positions and speeds etc of very small objects.

(2) Uncertainty caused by innate fuzzyness of very small objects such as electrons etc which have a partly-wave nature.

Each of these 2 sorts of uncertainty could have its own probability function.

Before the atom decays, the matter is limited to the insides of that atom's nucleus, and quantum mechanical rules apply to it.

Then the atom decays, and the matter becomes more and more wide-scale as the alpha particle flies, and knocks electrons out of many atoms, etc, until a Geiger-counter-type detector detects it, and etc as in the usual scenario. By then, most of the matter is on such a wide scale that it is now Newtonian, and the cat is definitely alive or definitely dead, and the main remaining uncertainty is Type 1, including uncertainty caused by the human eye being unable to see inside the closed box..

Edited by Anthony Appleyard

Share this post


Link to post
Share on other sites
29 minutes ago, Anthony Appleyard said:

https://en.wikipedia.org/wiki/Schrödinger's_cat

Quantum mechanics is founded on uncertainty principle. It seemed to me a while ago that there seems to be two sorts of uncertainty here.

There is nothing about the HUP in that article, and QM was not "founded" on the uncertainty principle. The HUP was introduced in 1927. QM had been in development for years at that point.

 

29 minutes ago, Anthony Appleyard said:

(1) Uncertainty caused by limitations in technology available to measure positions and speeds etc of very small objects.

(2) Uncertainty caused by innate fuzzyness of very small objects such as electrons etc which have a partly-wave nature.

Each of these 2 sorts of uncertainty could have its own probability function.

Schrödinger's cat is based on superposition.

 

Share this post


Link to post
Share on other sites

Exactly.
Shrodinger's cat is based on the superposition of states ( dead or alive ??? ) inherent in the wave function ( of the cat ???).
And when the box is opened, thereby collapsing the wave function through an interaction, The cat's quantum state ( ??? ) is 'fixed' as dead or alive.

Dead or alive are not quantum states, and the wave function of a cat in superposition is nonsensical.

Edited by MigL

Share this post


Link to post
Share on other sites
7 hours ago, swansont said:

That's to give you a random event to put the cat into the superposition, since whether or not the decay has occurred decides whether you've killed the cat. 

Isn't a decaying isotope in superposition as long as it doesn't interact? (and after that if wave functions don't collapse)

 

7 hours ago, swansont said:

The phonons are entangled, not the atoms. The atoms interacting is not the issue. It has to be an interaction with the quantum states in question.

Isn't that rather arbitrary? Who get's to decide which interactions count and which don't? 

7 hours ago, swansont said:

Wave functions are a mathematical construct.

That doesn't mean they collapse.

 

2 hours ago, MigL said:

Dead or alive are not quantum states, and the wave function of a cat in superposition is nonsensical.

The original description of the wave function of the cat collapsing when the box is opened, is indeed nonsensical.

However, I would like to know why you think a cat in superposition is nonsensical. Obviously dead or alive are not quantum states, but they could be macroscopic properties of myriads of compex quantum states.

Edited by Bender

Share this post


Link to post
Share on other sites
1 minute ago, Bender said:

Isn't a decaying isotope in superposition as long as it doesn't interact? (and after that if wave functions don't collapse)

Even if "Decayed" and "Not decayed" could be quantum states, the example is not relying upon that.

1 minute ago, Bender said:

Isn't that rather arbitrary? Who get's to decide which interactions count and which don't? 

It's not arbitrary at all. It's crucial to the problem.

1 minute ago, Bender said:

That doesn't mean they collapse.

Collapse is a descriptive term. You go from a superposition to a single eigenstate. The colloquial expression is that the wave function has collapsed.

1 minute ago, Bender said:

The original description of the wave function of the cat collapsing when the box is opened, is indeed nonsensical.

However, I would like to know why you think a cat in superposition is nonsensical. Obviously dead or alive are not quantum states, but they could be macroscopic properties of myriads of compex quantum states.

What atomic state correlates to being alive or dead? Is it spin orientation, orbital angular momentum, or the energy level?

Share this post


Link to post
Share on other sites
58 minutes ago, swansont said:

Even if "Decayed" and "Not decayed" could be quantum states, the example is not relying upon that.

Why not? Obviously the cat (and everything around it) can only be in superposition if the isotope can be.

 

59 minutes ago, swansont said:

It's not arbitrary at all. It's crucial to the problem.

Please illuminate me. In my mind, there are billions of atoms interacting, and then the billion-and-first (billion-and-oneth?) particle arrives and spoils the party. Why?

1 hour ago, swansont said:

Collapse is a descriptive term. You go from a superposition to a single eigenstate. The colloquial expression is that the wave function has collapsed.

Ok. Is there any evidence that systems ever go to a single eigenstate?

 

1 hour ago, swansont said:

What atomic state correlates to being alive or dead? Is it spin orientation, orbital angular momentum, or the energy level?

Either "none" or "a bunch", depending on whether systems revert to single eigenstates or not.

Share this post


Link to post
Share on other sites

I am sorry to repeat my message, but I have realized that I may have been a bit confusing:  by force of habit I used the word "matter" to mean "topic", although the word "matter" has another main meaning in this forum's purpose, and it was too late for me to edit my previous message

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

https://en.wikipedia.org/wiki/Schrödinger's_cat

Quantum mechanics is founded on an uncertainty principle. It seemed to me a while ago that there seems to be two sorts of uncertainty here.

(1) Uncertainty caused by limitations in technology available to measure positions and speeds etc of very small objects.

(2) Uncertainty caused by innate fuzzyness of very small objects such as electrons etc which have a partly-wave nature.

Each of these 2 sorts of uncertainty could have its own probability function.

Before the atom decays, the relevant events are limited to the insides of that atom's nucleus, and quantum mechanical rules apply to them.

Then the atom decays, and the relevant events become more and more wide-scale as the alpha particle flies, and knocks electrons out of many atoms, etc, until a Geiger-counter-type detector detects it, and etc as in the usual scenario. By then, most of the relevant events are on such a wide scale that they are now Newtonian, and the cat is definitely alive or definitely dead, and the main remaining uncertainty is Type 1, including uncertainty caused by the human eye being unable to see inside the closed box.

Edited by Anthony Appleyard

Share this post


Link to post
Share on other sites

To come back to the Original question,

Quote

Is "Schrodinger's Cat" the wrong interpretation for Copenhagen Interpretation?

 

The short answer is yes except that Shrodinger's Cat is not an interpretation. Application might be a better word?

Here is some very cogent thinking from John Gribbin.

I have highlighted the important part for this thread, but also the whole article on models is

copenhagen1.jpg.d44b198a11555e2699844bd394c91545.jpg

copenhagen2.jpg.9c59cc6a6b8a6ae9941474b6dcc4e6bd.jpg

 

 

Share this post


Link to post
Share on other sites
15 hours ago, Bender said:

Why not? Obviously the cat (and everything around it) can only be in superposition if the isotope can be.

It's irrelevant to the problem. You can write down states of an atom or nucleus and represent it as a superposition. There isn't anything absurd about that. It's chosen because it's random. 

15 hours ago, Bender said:

Please illuminate me. In my mind, there are billions of atoms interacting, and then the billion-and-first (billion-and-oneth?) particle arrives and spoils the party. Why?

It spoils the party if it does something to affect the phonon state in that example. Not all interactions will cause decoherence.

15 hours ago, Bender said:

Ok. Is there any evidence that systems ever go to a single eigenstate?

Happens all the time. Superposition and its removal is integral to how an atomic clock works. When we detect photons coming from our atoms, we know what transition they've made, and what state they are in.

15 hours ago, Bender said:

Either "none" or "a bunch", depending on whether systems revert to single eigenstates or not.

Those weren't your options.

43 minutes ago, studiot said:

To come back to the Original question,

 

The short answer is yes except that Shrodinger's Cat is not an interpretation. Application might be a better word?

Here is some very cogent thinking from John Gribbin.

I have highlighted the important part for this thread, but also the whole article on models is

copenhagen1.jpg.d44b198a11555e2699844bd394c91545.jpg

copenhagen2.jpg.9c59cc6a6b8a6ae9941474b6dcc4e6bd.jpg

 

 

The thing about interpretation is that they either make sense, or they don't (or they are somewhere on a spectrum between the two). There's a subjective element — it's whether they make sense to you. Because that's the function of an interpretation: to help you understand what's going on in the QM. It's like a toy model, and you use what works.

So, the Copenhagen interpretation is the right model to use if it helps you understand the example. The many-worlds interpretation is the right model to use if it helps you understand the example. Shut-up-and-calculate is the right model to use if it helps you understand the example.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.