Quantum uncertainty, and Schrodinger's cat

[Speakpigeon]

Have a camera in the box don't need the observer or the box. The camera doesn't know util it has recorded the dead cat or decay.

Point is a camera was added as if to change the problem. It didn't. It changed the mechanism for observing.

From the point of view of the observer outside, the camera inside the closed box doesn't change anything. It would if the observer outside could watch what the camera would be recording but that's not the scenario we have discussed.
EB

 

[skepticalbip]

The thought experiment is that the cat's state mirrors the state of the radioactive particle. The cat alive mirroring the decay not yet having occurred. The cat dead mirroring the particle having decayed. What is the state of the cat (which mirrors the quantum event) while the quantum event is in superposition (both having decayed and not yet decayed) as you seem to say is reality?

As I said plenty of times, the idea is that there is no one cat. There is one cat dead and there is one cat alive, and there is a sort of superposition of the two whereby an observer outside the closed box doesn't know whether the cat would be dead or would be alive if he ever opened the box right there.

The multiverse “solution” is no solution. It only phrases the same question in different terms plus it adds many, many more problems that need to be answered before it can be taken seriously.

It would still have the cat (now two) both alive and dead. Is which is in our universe and which is in a parallel universe only decided when “the box is opened”? If so then you still have the Copenhagen interpretation – the cat (now two) both alive and dead and which is in our universe set by observation.

A major problem created would be that the idea would have the entire mass and energy of the universe created for every quantum event - the creation of that new parallel universe. This is a serious violation of conversation of mass and energy. How does this happen?

I don't pretend I understand the whole of it and I'd be certainly interested if you had an argument showing that the cat is definitely dead or alive even before the observer has a look-in, for example if there is a camera inside the closed box. To me, it's clear that if there can be a superposition of two cats, there can also be a superposition of two cameras, as I already said.

I have no argument or preference either way.

The camera in the box is just an “observer” which satisfies the condition of the Copenhagen interpretation so there is no superposition. This makes the lab dude outside irrelevant and the thought experiment itself irrelevant.

Still, I don't know that the observer would know that there is in the box just one camera or a superposition of two, one cat or a superposition of two, because the box is closed, which is the point of the experiment.
EB

I don’t even know what this means.

 

[Juma]

Second, I'm on record for criticising people, including scientists, who are happy to say that the same atom (or photon, or electron, or cat) is in two incompatible states. Still, I think basically they just don't pay attention to the way they talk. No big deal except that they confuse the man on the street.

Yet, even if we recognise that it is not the case that one atom is ever in two incompatible states, we could still have two real states at the "same time", each somehow issued from the same object (through entanglement I guess). My point is that if this is so then we no longer have one object but two, scientists careless with words notwithstanding. I also understand that this view of two objects in two different states but coming from one object is that of scientists working on the idea of parallel universes (or histories). I don't know who is right but I like the idea.

So an electron with measured spin in X will then somehow be 4 electrons with all properties the same except for the different Y and Z spins? How come they behave as one then? How come 1 of them mysteriously disappears and another appears if we measure the Z spin?

No, your identity game is just silly because it isnt needed. There os much less problem if we say thay it has all spinn states untill measured.

 

[fromderinside]

Have a camera in the box don't need the observer or the box. The camera doesn't know util it has recorded the dead cat or decay.

Point is a camera was added as if to change the problem. It didn't. It changed the mechanism for observing.

From the point of view of the observer outside, the camera inside the closed box doesn't change anything. It would if the observer outside could watch what the camera would be recording but that's not the scenario we have discussed.
EB

Indeed. That's why the insertion of a camera inside the box as was done earlier is useless and meaningless, as is, but the way, having a box containing a dying cat. All the paradigm did was change something as happening unexpectedly to something happening when the observer detected the event. In no way did the paradigm explain the mathematics of uncertainty in situations where the measured is smaller than is the ability to measure.

 

[Jesse]

It would still have the cat (now two) both alive and dead. Is which is in our universe and which is in a parallel universe only decided when “the box is opened”? If so then you still have the Copenhagen interpretation – the cat (now two) both alive and dead and which is in our universe set by observation.

No, the many-worlds interpretation says that nothing special happens at the moment of measurement, unlike the Copenhagen interpretation which postulates a "collapse" on measurement distinct from the normal deterministic equation for wavefunction evolution. Opening the box just means the outside observer becomes entangled with the system in the box, in the way that would be predicted by the standard deterministic equations of QM during any interaction between quantum systems (in the context of the Copenhagen interpretation, this is what happens with interactions that take place between measurements, so they don't involve any collapse--the many-worlds interpretation just says 'measurement' is no different from any other quantum interaction).

A major problem created would be that the idea would have the entire mass and energy of the universe created for every quantum event - the creation of that new parallel universe. This is a serious violation of conversation of mass and energy. How does this happen?

There are no parallel universes "created" at any distinct moments. There's just a single universal wavefunction, evolving deterministically according to the Schroedinger equation, which contains a superposition of very different position states (like "living cat" and "dead cat"). In QM energy conservation for an evolving wavefunction is expressed in terms of the idea that the expectation value for energy doesn't change from one moment to the next, and this would be true of the universal wavefunction too.

Here's good article on the many-worlds (or Everett) interpretation, and how it doesn't actually start from the premise of "parallel universes" but just from assuming the deterministic equation governing wavefunction evolution applies at all times: http://www.preposterousuniverse.com...y-worlds-interpretation-of-quantum-mechanics/

 

[Speakpigeon]

Still, I don't know that the observer would know that there is in the box just one camera or a superposition of two, one cat or a superposition of two, because the box is closed, which is the point of the experiment.
EB

I don’t even know what this means.

Sorry, I can't help, the English is good, you're on your own.
EB

 

[Speakpigeon]

The multiverse “solution” is no solution. It only phrases the same question in different terms plus it adds many, many more problems that need to be answered before it can be taken seriously.

It would still have the cat (now two) both alive and dead. Is which is in our universe and which is in a parallel universe only decided when “the box is opened”? If so then you still have the Copenhagen interpretation – the cat (now two) both alive and dead and which is in our universe set by observation.

I wouldn't expect the many-world interpretation to say that the two states of dead cat and cat still alive could come together again like it's possible for particles. However, just as there is no one cat once the box is closed, there will be no one observer once the box is opened. Instead there will be two observers, one looking at a dead cat, the other looking a cat still alive.

A major problem created would be that the idea would have the entire mass and energy of the universe created for every quantum event - the creation of that new parallel universe. This is a serious violation of conversation of mass and energy. How does this happen?

I wouldn't be too concerned about energy myself but I don't know what is the many-world interpretation's answer to that.

My intuition is that energy should be weighted according to the respective probabilities of each branch (or history or whatever). As you know, the total of them will give exactly 1.

Once you understand that you have to look at it as a mathematical problem rather than an ontological one it becomes a no brainer.
EB

 

[skepticalbip]

Once you understand that you have to look at it as a mathematical problem rather than an ontological one it becomes a no brainer.
EB

As a mathematical problem, the "Schrodinger's cat problem" is just a simple wave function – nothing more. Interpretations of what that wave function "means" in the real world are philosophical interpretations. Your appeal to a multiverse is philosophical not mathematical. It is your philosophical explanation that needs defending, not the math.

Those purely mathematical types who take probabilities as real would say, "shut up and calculate".

ETA:
Here's a "nerd shirt" I designed that explains the "debate":

 

[Kharakov]

Where is the male bovine BM?

 

[skepticalbip]

No, the many-worlds interpretation says that nothing special happens at the moment of measurement, unlike the Copenhagen interpretation which postulates a "collapse" on measurement distinct from the normal deterministic equation for wavefunction evolution. Opening the box just means the outside observer becomes entangled with the system in the box, in the way that would be predicted by the standard deterministic equations of QM during any interaction between quantum systems (in the context of the Copenhagen interpretation, this is what happens with interactions that take place between measurements, so they don't involve any collapse--the many-worlds interpretation just says 'measurement' is no different from any other quantum interaction).

A major problem created would be that the idea would have the entire mass and energy of the universe created for every quantum event - the creation of that new parallel universe. This is a serious violation of conversation of mass and energy. How does this happen?

There are no parallel universes "created" at any distinct moments. There's just a single universal wavefunction, evolving deterministically according to the Schroedinger equation, which contains a superposition of very different position states (like "living cat" and "dead cat"). In QM energy conservation for an evolving wavefunction is expressed in terms of the idea that the expectation value for energy doesn't change from one moment to the next, and this would be true of the universal wavefunction too.

Here's good article on the many-worlds (or Everett) interpretation, and how it doesn't actually start from the premise of "parallel universes" but just from assuming the deterministic equation governing wavefunction evolution applies at all times: http://www.preposterousuniverse.com...y-worlds-interpretation-of-quantum-mechanics/

Admittedly, I haven't tried to keep up with the multiverse enthusiast. It has been a while but the last I read was one of them explaining the plethora of real full universes, as real and complex as the one we experience. Their use of the multiverse was to explain that all the solutions derived in string theory that can not possibly apply to our universe were actually describing reality in some other universe that was every bit as real as ours. Essentially (from what I could determine) saying that string theory can not possibly yield any invalid solutions.

Your link was interesting, thanks.

 

[Underseer]

I would love to know what exactly can be an "observer", and how it makes it's "observations".

How does something observe when it has no eyes?

Are we twisting the definition of "observer"?

I think early QM scientists started with a proper observer (them ) but then generalised the notion to measurement and further to interaction. As I understand it, each term suits some scientists but not others.

So the term used may hint at a particular philosophical position.
EB

Sorry for the delayed response.

No, the thing that interacts with the particle being measured is what alters the state of the particle, so that is what counts as the "observer" mathematically.

In the case of Schrodinger's cat, the chemicals in the petri dish are what are interacting with the subatomic particle in question, so the chemicals are the observer. The human who opens the box is not the observer.

 

[Speakpigeon]

Whether a cat can be both alive and dead is a matter for biology not physics.

But all one has to do is produce a cat that is both alive and dead to demonstrate my error.

Biology is a matter of physics.

Define dead or alive in terms of QM equations please.
EB

 

[fromderinside]

First we need definitions of dead and alive. If by dead you only mean quit working the calculations can be found in any upper division physics text.

 

[Speakpigeon]

We all know what "dead" means. A dead cat is not a cat that quit working.
EB

 

[fromderinside]

What is the difference between a thing that has quit working permanently and a dead cat then?

 

[Bomb#20]

What is the difference between a thing that has quit working permanently and a dead cat then?

 

[Speakpigeon]

What is the difference between a thing that has quit working permanently and a dead cat then?

Precisely, we don't seem to know.


And, as a point on English, I quit working permanently and I'm not dead (as far as I can tell).
EB

 

[Speakpigeon]

What is the difference between a thing that has quit working permanently and a dead cat then?

Yeah, a bit like me.

Although I'm not entirely sure he's not dead.
EB