# Schrödinger's cat & Wigner's friend, An execize in logic..

#### Hicup

DP Veteran
Disclaimer: I saw no area to post on the metaphysical, so i posted it here. If there is a more appropriate place please move it there, just let me know where so i can find it.

What follows is an exercise in pure logical deduction based on parameters that are not necessarily well defined, but accepted as part of the standard model in particle physics.

Copenhagen interpretation says that a system stops being a superposition of states and becomes either one or the other when an observation takes place. Schrödinger through his cat, Link showed meta-physically, that a state can be any number of states, but not necessarily observed directly for it to be true. In my opinion, the realization and cognizant function of the observer, is only directly related to the state of the observer, and thus, any other interaction that changes the existential state of that interacted with.

Take Wigner's friend, but go further than that; assuming that "friends" need not be tied quantumly as entirely dependant of each other for it to be true. In this scenario, the friend carries through the wave-function of the state. The state being whatever the cat's state was after opening the box. Now applying Everetts Many World Interpretation, we now have a dilemma; the dilemma being that if Everett is correct and parallele universes exist, then what would happen if Wigner's friend met it's identical (Parallele universal) Wigner?

For example, whether the cat is dead or alive is directly related to the instant observation, and thus, as a direct extrapolation, said to be only static when observed; or observable only when directly measured. For instance, if Wigner was the observer and the cat was dead, he carries the wave-function to that of the cat being dead at that monent of observation. At this time, a parallele universe is set in motion, where at the parallel moment of the observation, Wigner would have obsered a living cat. Now, Wigner's friend, likewise, observes the cat being dead, like the instant (Wigner alive scenario) observation, and he too begins a parallel universe where the cat is alive. Now, assuming there are no barriers to dual wave-functions beng carried on identically in the same universe, then time becomes the issue of observation.

This refutes Schrödinger's cat because both universes require that time separate the two oberservations, but time itself does not preclude the interaction of the parallel friend of Wigner, nor the parallel Wigner himself, yet, it must, if one assumes that parallel states are dependant on the instant of time, and decoherent of each other. If one agree's that this is absurd, then it is true that the Copenhagen interpretation is in fact true and states become such only when directly measured or observed.

Thoughts?

Tim-

#### Hicup

DP Veteran
I'm embarrassed to be posting to my own thread first. Come on. I know there are some scientists out here. I've read some very intelligent posts, grounded in the scientific method on this forum. My exercise has holes, and I invite criticism.

Tim-

#### iangb

##### Lurker
DP Veteran
I'm embarrassed to be posting to my own thread first. Come on. I know there are some scientists out here. I've read some very intelligent posts, grounded in the scientific method on this forum. My exercise has holes, and I invite criticism.

Tim-
I'm having difficulty understanding the contents of your OP. Sentences like "Take Wigner's friend, but go further than that; assuming that "friends" need not be tied quantumly as entirely dependant of each other for it to be true." don't make any kind of grammatical sense, so I'm having to guess at your main meaning...

As far as I'm aware, Schrodingers cat is an often-misunderstood thought experiment. From what I can remember, Schrodinger originally proposed it to demonstrate the absurdity of needing a human observer in order to collapse a waveform - the point of the thought experiment is that the cat won't be 'half alive/half dead', because it can observe itself. More than that; the geiger counter itself detecting the decaying particle (in order to release the poison) is an act of 'observation'.

In fact, Schrodinger's Cat implies that a wavefunction will remain in flux until it physically interacts with something else, at which point it will collapse down to the particle state. If you run Young's double slit experiment with single photons and extremely sensitive photographic film, you will see interference fringes regardless of whether anyone is watching the experiment as it takes place or not.

#### Redress

##### Liberal Fascist For Life!
DP Veteran
Unless you put photon detectors at the slits of course.

2-slit experiment > *

Schrodinger's Cat shows the problem of applying quantum theory, which works on a subatomic level, to objects which are not on that level.

#### iangb

##### Lurker
DP Veteran
Unless you put photon detectors at the slits of course.

2-slit experiment > *

Schrodinger's Cat shows the problem of applying quantum theory, which works on a subatomic level, to objects which are not on that level.
The largest objects that have demonstrated wave/particle duality (in Young's double-slit experiment) have been buckyballs. That properly blew me away when I found out. They're huge!

#### Redress

##### Liberal Fascist For Life!
DP Veteran
The largest objects that have demonstrated wave/particle duality (in Young's double-slit experiment) have been buckyballs. That properly blew me away when I found out. They're huge!

WTF is a buckyball?

Edit: Never mind, looked it up, and LoL at the name of them.

#### Hicup

DP Veteran
iangb -
I'm having difficulty understanding the contents of your OP. Sentences like "Take Wigner's friend, but go further than that; assuming that "friends" need not be tied quantumly as entirely dependant of each other for it to be true." don't make any kind of grammatical sense, so I'm having to guess at your main meaning...

Hmm.. You're right, it does sound awkward. I think that I assumed you looked at the link, and rather than having to explain the postulate of Wigner's Friend, what followed would be understood. It should read: "Take Wigner's friend, but go further than that; assuming that the "friends" need not be tied together quantumly and or entirely dependant of each other, for it to be true." This is suggesting that it is possible for Wigner who left, and comes back - meets up with his friend, who already knows the result of the experiment, and Wigner is determined, by the first observation to hear only one answer . The only difference is that Wigner's friend, Wigner meets, is the one that had the opposite result than the one (this) Wigner is expected (destined) to learn of. Meaning, at the moment the observation is made, and determined, the function of the wave moves outward with the direction of "space-time". Past the observer (Wigner's friend) outward further and further until the observation is determined for the entire universe. One question I have, is, if the appearance of how we perceive time as a measurement of change, is physically how time really is. (Meaning we have it right) Then does time play a role in the determination? If it does, then how is any observation of the cat, the counter, or Wigner's friend, have any relevance in the wave function of the particle?

My postulate, is that, if one accepts that there are in infinite number of space time continuums (Which conventional physics seems to be heading) then the observation of the cat being dead or alive is what triggers the separation of timelines. The criticism of Schrödinger, in his experiment, is that the cat, and as you point out, the Geiger counter are measurements, and thus, move the determination further up, which results in the human observer merely getting second hand news. Essentially the system is not closed, if it can be measured.

But given the above, and if the effects of observing the particle are felt at the speed of space-time, it is logically consistent to conclude that, an observer wouldn't "feel" the effects of the determinate particle immediately, or everywhere at once in the universe. What I mean by this is, is at the moment the particle is measured, everything in the universe that is determined (Destined) to interact with that space time continuum must have something physically that ties it to the timeline. What is this physical thing? If the particle is potentially observable in one place, once observed, it ceases to have any other potential of being observed directly, elsewhere. Unless, it can be in two places at the same space time? If it can be in two places at once, then so too can two versions of Wigner's friend. What's stopping either version of Wigner's friend interacting with the opposite (destined) determined version of Wigner? Essentially, the Wigner that was supposed to hear the bad news, got swapped with the Wigner that got the good news? If this can happen, then we prove that the particle is everywhere at once, if it can't happen, because at the moment the cat, the counter, or Wigner's friend made the measurement, the determination was set, then we prove that in the first instant the universe, as we know it, is set, (Observed) everything else is determined. If the universe is determined then Schrödinger's Cats fate, has already been determined, and the experiment is useless.

This postulate brings up some interesting questions. Does space time have a speed limit? Can there be free will? Is the simple act of a measurement enough to tie a particle physically with a particular space time continuum? If tied to a space time continuum, once observed, then wouldn't that fixed timeline begin at the very first instant?

Thoughts?

Tim-

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#### iangb

##### Lurker
DP Veteran
iangb -
My postulate, is that, if one accepts that there are in infinite number of space time continuums (Which conventional physics seems to be heading) then the observation of the cat being dead or alive is what triggers the separation of timelines. The criticism of Schrödinger, in his experiment, is that the cat, and as you point out, the Geiger counter are measurements, and thus, move the determination further up, which results in the human observer merely getting second hand news. Essentially the system is not closed, if it can be measured.

But given the above, and if the effects of observing the particle are felt at the speed of space-time, it is logically consistent to conclude that, an observer wouldn't "feel" the effects of the determinate particle immediately, or everywhere at once in the universe. What I mean by this is, is at the moment the particle is measured, everything in the universe that is determined (Destined) to interact with that space time continuum must have something physically that ties it to the timeline. What is this physical thing? If the particle is potentially observable in one place, once observed, it ceases to have any other potential of being observed directly, elsewhere. Unless, it can be in two places at the same space time? If it can be in two places at once, then so too can two versions of Wigner's friend. What's stopping either version of Wigner's friend interacting with the opposite (destined) determined version of Wigner? Essentially, the Wigner that was supposed to hear the bad news, got swapped with the Wigner that got the good news? If this can happen, then we prove that the particle is everywhere at once, if it can't happen, because at the moment the cat, the counter, or Wigner's friend made the measurement, the determination was set, then we prove that in the first instant the universe, as we know it, is set, (Observed) everything else is determined. If the universe is determined then Schrödinger's Cats fate, has already been determined, and the experiment is useless.

This postulate brings up some interesting questions. Does space time have a speed limit? Can there be free will? Is the simple act of a measurement enough to tie a particle physically with a particular space time continuum? If tied to a space time continuum, once observed, then wouldn't that fixed timeline begin at the very first instant?

Thoughts?

Tim-
The point of the many-worlds idea is that it eliminates (to some extent) the idea of a waveform being in flux. Every quantum interaction instantaneously creates a world/universe where each different possible outcomes is determined; so in the thought experiment, two universes are created; one where that cat will live, one where it will die. You just don't know which universe you are in until you open the box.

Traditionally, the 'speed of space-time' is the speed of light. That isn't necessarily true when you start talking about quantum, but in general that's the case: if our sun were to spontaneously vanish this instant, Earth would continue to feel it's gravitational pull for another 7 minutes or so (the same amount of time it takes light to get to us from the sun).

As for 'free will' - our brain can be considered to be a mass of quantum interactions. 'Free will', should it exist, is the ability to choose which universe you want to go into.

#### spud_meister

##### Veni, vidi, dormivi!
DP Veteran
if our sun were to spontaneously vanish this instant, Earth would continue to feel it's gravitational pull for another 7 minutes or so (the same amount of time it takes light to get to us from the sun).

it wouldn't, gravity isn't a wave, it acts instantly, like magnetism.

DP Veteran
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#### Hicup

DP Veteran
You just don't know which universe you are in until you open the box

But what you never open the box? What universe are you in now?

Tim-

#### iangb

##### Lurker
DP Veteran
But what you never open the box? What universe are you in now?

Tim-
Another one altogether!

#### Hicup

DP Veteran
it wouldn't, gravity isn't a wave, it acts instantly, like magnetism.

Well, we know what gravity does, and we've developed pretty good models that predict it very well, but we still do not know what it is. All of the forces in the universe seem to have a particle that is associated with it. For gravity, we hypothesize that the graviton particle is there, although no one has witnessed it. However, we "are" looking for them. We don't know how matter gains mass, or why it seems to be completely arbitrary. The whole point, or one of the main ideas behind building the LHC, is to find the Higgs Boson. The "God" particle.

If the Sun vanished, it would take roughly 8 minutes for us on the Earth to even know it had happened, both gravitationaly, and observing the light, or lack thereof.

Some physicists are suggesting that there may not have always been a speed limit for the speed of light. I've read some very interesting papers on this. The standard model of creation has some holes in it, certainly, but with inflation, dark matter, dark energy, and now dark flow, we think we're still on the right track. What is dark matter, dark energy, and dark flow? Got me.. But scientists are trying desperately to find out. The "dark" represents our ignorance, and is aptly named.

Tim-

#### Hicup

DP Veteran
Another one altogether!

But is the cat alive or dead? According to you, opening the box tells you which universe you're in, but the cat already knows. In fact, in the first instant, way before the cat, and way before human life, the particles were fixed. Now we perform the experiment in the here and now. Is the cat still considered to be both alive and dead until you open the box; even though the outcome has already been set by the first instant of the universe. If yoo'd agree that it isn't set, then you must accept that the standard model of QM, QED is missing something.

Tim-

#### iangb

##### Lurker
DP Veteran
But is the cat alive or dead? According to you, opening the box tells you which universe you're in, but the cat already knows. In fact, in the first instant, way before the cat, and way before human life, the particles were fixed. Now we perform the experiment in the here and now. Is the cat still considered to be both alive and dead until you open the box; even though the outcome has already been set by the first instant of the universe. If yoo'd agree that it isn't set, then you must accept that the standard model of QM, QED is missing something.

Tim-
No, the cat is definitely alive or dead, no matter if you open the box or not. Like I said, you're in one of those universes already, you just don't know which one.

"Another one altogether" referred to the fact that you deciding to open the box was probably as the result of another quantum interaction, hence more branching universes.

EDIT: It's worth pointing out that this is just the 'many-worlds' interpretation. It doesn't even have to go that far; we can have a probabilistic waveform that exists until physical interaction occurs, at which point it collapses to a particle-point - and the cat dies or lives based on whether that physical interaction is the particle decaying, or the box being opened.

#### USViking

DP Veteran
Disclaimer: I am not a Scientist.

Disclaimer: I saw no area to post on the metaphysical, so i posted it here. If there is a more appropriate place please move it there, just let me know where so i can find it.

Metaphysics is a branch of Philosophy. There is a section
of this board titled "Religion & Philosophy".

Quantum Mechanics is a branch of Physics. This section
of the board titled "Science and Technology"is an appropriate forum.

What follows is an exercise in pure logical deduction based on parameters that are not necessarily well defined, but accepted as part of the standard model in particle physics.
Copenhagen interpretation says that a system stops being a superposition of states and becomes either one or the other when an observation takes place.

OK.

Schrödinger through his cat, Link showed meta-physically, that a state can be any number of states, but not necessarily observed directly for it to be true.

Schroedinger himself did not take his famous "Cat" seriously
in a physical sense. What he was trying to accomplish with
"Kitty" was imposition of a reductio ad adsurdum on the rival
Copenhagen school.

In Schroedingers view Copenhagen was forced to accept that "Kitty"
had to be either:

(1) Alive and dead simultaneously, or

(2) "Smeared out" (Schroedinger's expression) in a continuum of states
extending from life to death.

Unfortunately for Schroedinger (but fortunately for "Kitty") his Copenhagen
opponents stuck to their guns and carried the day, and for decades Physics
generally accepted that the act and agent of measurement have special status.

In my opinion, the realization and cognizant function of the observer, is only directly related to the state of the observer, and thus, any other interaction that changes the existential state of that interacted with.

You have lost me here.

Take Wigner's friend, but go further than that; assuming that "friends" need not be tied quantumly as entirely dependant of each other for it to be true. In this scenario, the friend carries through the wave-function of the state. The state being whatever the cat's state was after opening the box.
You have lost me here also.

Eugene Wigner proposed an extreme interpretation of Quantum Mechanics
of his own, namely that existence was observer-based, a la Bishop Berkeley:
Esse Est Percipi. Under this interpretation what Schrodinger intended as
“burlesque” (his word)is accepted as a fact of nature.

Now applying Everetts Many World Interpretation, we now have a dilemma; the dilemma being that if Everett is correct and parallele universes exist, then what would happen if Wigner's friend met it's identical (Parallele universal) Wigner?

The argument falls apart at this point because the parallel universes
cannot IN PRINCIPLE communicate after they split:

Wigner's “Friends” are forever completely sundered IN PRINCIPLE.

In fact MW was meant as an mutually exclusive alternative to the
Copenhagen-Wigner interpretations.

For example, whether the cat is dead or alive is directly related to the instant observation, and thus, as a direct extrapolation, said to be only static when observed; or observable only when directly measured. For instance, if Wigner was the observer and the cat was dead, he carries the wave-function to that of the cat being dead at that monent of observation. At this time, a parallele universe is set in motion, where at the parallel moment of the observation, Wigner would have obsered a living cat. Now, Wigner's friend, likewise, observes the cat being dead, like the instant (Wigner alive scenario) observation, and he too begins a parallel universe where the cat is alive.

OK, I think.

Now, assuming there are no barriers to dual wave-functions beng carried on identically in the same universe (emphasis added), then time becomes the issue of observation.
MW assumes that there are just such barriers, and that they are insurmountable
IN PRINCIPLE.

This refutes Schrödinger's cat because both universes require that time separate the two oberservations, but time itself does not preclude the interaction of the parallel friend of Wigner, nor the parallel Wigner himself, yet, it must, if one assumes that parallel states are dependant on the instant of time, and decoherent of each other. If one agree's that this is absurd, then it is true that the Copenhagen interpretation is in fact true and states become such only when directly measured or observed.
I am lost again.

Thoughts?
I think we are little if any closer to identifying the correct interpretation of QM
than we were more than 80 years ago.

It has been one of the most intractable problems in the history of science.