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Can you explain schrodinger's cat?

Thaumaturgy
Posts: 166
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6/4/2012 10:04:14 AM
Posted: 4 years ago
It's a cat. No one understands cats. The best thing one could do is probably just go ahead and collapse the waveform for once and for all then go buy a dog. A MUCH better pet.
lewis20
Posts: 5,093
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6/4/2012 10:08:36 AM
Posted: 4 years ago
That video was actually a pretty good explanation as long as you have a little bit of background in the area.
Which part don't you understand?
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Thaumaturgy
Posts: 166
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6/4/2012 10:17:30 AM
Posted: 4 years ago
The idea is, as I understand it (mind you my use of QM is limited to the higher order chemical applications, so digging this deeply into it is not something I do that often), but generally the idea is that the radioactive isotope whose decay essentially defines the life or death of the cat, when unobserved, exists in a "superposition" of states: decayed and undecayed.

This apparently falls out of the Schroedinger Equation and is called "superposition".

The weirdness of the thought experiment is that it directly couples the quantum world with the non-quantum world. How does one know which state the cat is in? If I am not mistaken, it is not possible to say because the element itself is both decayed and undecayed and hence the cat is both dead and alive.

This leads to a couple of different schools of thought: the Copenahagen interpretation in which the observer (or the act of observation, not necessarily a "conscious observer") defines when the "waveform collapses" into one state or another. The other school is Everett's "Many Worlds" interpretation which means an entirely new universe is spawned every time a superposition of states exists. Open the box and you see a dead cat while in a new universe you see a live cat.
(BTW: does anyone remember the song "Novocaine for the Soul" by the Eels? The lead singer for the Eels is the son of Hugh Everett the physicist who came up with the "Many Worlds" hypothesis...just so ya know. There's a cool Nova documentary where they talk with Everett the younger about his efforts to get to know more about his father as an adult.)

There's a couple other schools of thought as I understand but I don't know much about them.
tBoonePickens
Posts: 3,266
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6/4/2012 10:43:57 AM
Posted: 4 years ago
At 6/4/2012 9:57:54 AM, Jon1 wrote:


I don't get it *_*

If a tree falls in the forest and there is no one there to hear it, does it make a noise?
WOS
: At 10/3/2012 4:28:52 AM, Wallstreetatheist wrote:
: Without nothing existing, you couldn't have something.
tBoonePickens
Posts: 3,266
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6/4/2012 12:10:35 PM
Posted: 4 years ago
At 6/4/2012 10:43:57 AM, tBoonePickens wrote:
At 6/4/2012 9:57:54 AM, Jon1 wrote:


I don't get it *_*

If a tree falls in the forest and there is no one there to hear it, does it make a noise?

A) "The state of superposition cannot be observed." -Video @ 2:36
B) ie, The state of superposition cannot be verified.
C) ie, superposition is unfalsifiable.
WOS
: At 10/3/2012 4:28:52 AM, Wallstreetatheist wrote:
: Without nothing existing, you couldn't have something.
Ren
Posts: 7,102
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6/4/2012 1:21:20 PM
Posted: 4 years ago
Read through this thread: http://www.debate.org...

You will get precisely what you asked for, + a lot more.

Then, perhaps, we can pick up where with wherever you'd like to go from there! ^_^
WriterDave
Posts: 934
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6/4/2012 1:49:22 PM
Posted: 4 years ago
My understanding is this: The cat has a fifty-fifty chance of dying in the given time period, based on whether a particle decays, which is unpredictable. Schrodinger wrote that based on the then widely accepted models of quantum mechanics, one is forced to say that the cat is BOTH alive and dead, which is absurd, so we should disregard that part of quantum mechanics.

To his dismay, the other QM physicists said, "Hey, you're right! What other metaphysical implications can Schrodinger's cat-in-the-box entail?" And Schrodinger did a facepalm, and we're still having fun with the cat today.

What it actually MEANS depends on who you ask.
Writer. Liberal atheist. Official "Official of the FREEDO Bureaucracy" of the FREEDO Bureaucracy.

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Wnope
Posts: 6,924
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6/4/2012 2:06:41 PM
Posted: 4 years ago
I had a thought.

Couldn't the cat and box themselves lead to decoherence of the superposition even without someone observing?
tBoonePickens
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6/4/2012 2:52:08 PM
Posted: 4 years ago
At 6/4/2012 2:06:41 PM, Wnope wrote:
I had a thought.

Couldn't the cat and box themselves lead to decoherence of the superposition even without someone observing?

Can one actually observe a superposition?
WOS
: At 10/3/2012 4:28:52 AM, Wallstreetatheist wrote:
: Without nothing existing, you couldn't have something.
WriterDave
Posts: 934
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6/4/2012 4:00:29 PM
Posted: 4 years ago
At 6/4/2012 2:06:41 PM, Wnope wrote:
I had a thought.

Couldn't the cat and box themselves lead to decoherence of the superposition even without someone observing?

According to the Objective Collapse interpretation, in which the wave function collapses when it meets or exceeds a particular physical threshold, yes. I'm not sure how many people subscribe to that interpretation, though.
Writer. Liberal atheist. Official "Official of the FREEDO Bureaucracy" of the FREEDO Bureaucracy.

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Wnope
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6/4/2012 7:03:32 PM
Posted: 4 years ago
At 6/4/2012 2:52:08 PM, tBoonePickens wrote:
At 6/4/2012 2:06:41 PM, Wnope wrote:
I had a thought.

Couldn't the cat and box themselves lead to decoherence of the superposition even without someone observing?

Can one actually observe a superposition?

Perhaps not, but from what little I know, aren't there certain conditions that don't involve interference from an agent (such a higher temperatures) which influence coherence?
Wnope
Posts: 6,924
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6/4/2012 7:04:31 PM
Posted: 4 years ago
At 6/4/2012 4:00:29 PM, WriterDave wrote:
At 6/4/2012 2:06:41 PM, Wnope wrote:
I had a thought.

Couldn't the cat and box themselves lead to decoherence of the superposition even without someone observing?

According to the Objective Collapse interpretation, in which the wave function collapses when it meets or exceeds a particular physical threshold, yes. I'm not sure how many people subscribe to that interpretation, though.

What's the popular version these days? That we perceive wave collapse but it does not actually happen in an objective sense?
Ren
Posts: 7,102
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6/4/2012 7:26:51 PM
Posted: 4 years ago
At 6/4/2012 2:52:08 PM, tBoonePickens wrote:
At 6/4/2012 2:06:41 PM, Wnope wrote:
I had a thought.

Couldn't the cat and box themselves lead to decoherence of the superposition even without someone observing?

Can one actually observe a superposition?

Actually, yes.

It's been macrocosmically observed on a couple of occasions, usually involving electrical currents through mismatched conductors, for example: http://www.nature.com...

Kind of solidified the stance that physicists are most often accepting nowadays.

That said, technically, Wnope, it depends on whether the cat measures itself. :P Seeing, methinks, might be one way.
Wnope
Posts: 6,924
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6/4/2012 7:38:20 PM
Posted: 4 years ago
I've come across "Consistent Histories" interpretation, and I have to say it is much more satisfying than Copenhagen. What are your feelings on it (Ren or tboone)?
Thaumaturgy
Posts: 166
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6/4/2012 9:53:04 PM
Posted: 4 years ago
At 6/4/2012 12:10:35 PM, tBoonePickens wrote:
A) "The state of superposition cannot be observed." -Video @ 2:36
B) ie, The state of superposition cannot be verified.
C) ie, superposition is unfalsifiable.

Superposition apparently falls out of the mathematics. Apparently superposition is an outcome of the nature of the Schroedinger equation which is "linear" and as such any "linear combination of solutions" to it will also be a solution to the equation.

So it is a necessary part of the math, not necessarily something someone "observed".

Also remember that antimatter was something that fell out of Dirac's equation and it later was found to be real.

Not sure if one "falsifies" a mathematical relationship.
Thaumaturgy
Posts: 166
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6/4/2012 9:55:44 PM
Posted: 4 years ago
At 6/4/2012 1:49:22 PM, WriterDave wrote:
My understanding is this: The cat has a fifty-fifty chance of dying in the given time period, based on whether a particle decays, which is unpredictable. Schrodinger wrote that based on the then widely accepted models of quantum mechanics, one is forced to say that the cat is BOTH alive and dead, which is absurd, so we should disregard that part of quantum mechanics.

To his dismay, the other QM physicists said, "Hey, you're right! What other metaphysical implications can Schrodinger's cat-in-the-box entail?" And Schrodinger did a facepalm, and we're still having fun with the cat today.

What it actually MEANS depends on who you ask.

I think the reality is a bit more subtle than just the 50/50 chance concept. I believe that it relates to the literal "superposition of states" of the atom. Both decayed and undecayed with are linked directly to a macro-scale object (the cat). I think this bothered Schroedinger so he came up with the thought experiment to point out this problem, but I think it is more than just "You don't know until you look in the box", it is more of a case of the true "quantum weirdness" factor.
Thaumaturgy
Posts: 166
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6/4/2012 9:57:04 PM
Posted: 4 years ago
At 6/4/2012 2:06:41 PM, Wnope wrote:
I had a thought.

Couldn't the cat and box themselves lead to decoherence of the superposition even without someone observing?

I believe Bohr was not necessarily a fan of the need of some conscious "observer", and realized even just the geiger counter itself, in the act of "measuring" the decay could collapse the waveform. (But I'm a bit hazy on this)
Ren
Posts: 7,102
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6/4/2012 10:52:35 PM
Posted: 4 years ago
At 6/4/2012 7:38:20 PM, Wnope wrote:
I've come across "Consistent Histories" interpretation, and I have to say it is much more satisfying than Copenhagen. What are your feelings on it (Ren or tboone)?

Wow, it is extremely interesting. It was also essential. Something tells me that this was established as a means disambiguate the difference between forced computational superposition, and actual operational superposition.

What I mean is, in the quantum world, where particles are always in flux, there is actual superposition, where particles do exist in several places at the same time. Or, it appears in the same place twice within the same moment, if that makes sense.

In the Newtonian physical world, matter is not in such flux, generally speaking, so using Galilean transformations, systems can be predicted reliably. However, this breaks down when one considers aspects of systems that enter into the quantum world, such as the movement of energy throughout these systems. This results in a degree of uncertainty when attempting to describe these systems comprehensively. Enter Consistent Histories, where an algebraic framework is applied to a predetermined distribution on the quantum level, then extrapolated to a larger framework on the Newtonian level.

I think that's rather brilliant, and necessary, to distinguish the difference between actual superposition, and computational superposition. In this way, the determination of a trajectory does not require the collapse of a wave equation into a linear equation, and instead, simply the combination of separate dynamics.

This can help bridge the gap between Newtonian and Quantum physics. This is kind of big, actually.

It also establishes once and for all -- although electrons and photons can exist in two places simultaneously, or the same place twice at the same time, a circumstance with a given probability needn't exist in every state that it can possibly exist until it's measured.
Ren
Posts: 7,102
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6/4/2012 10:54:18 PM
Posted: 4 years ago
This is something I've been thinking about a lot, and couldn't make up my mind. I mean, generally speaking, given quantum realities, I was literally leaning toward Newtonian superposition as a reality, but it did seem kind of funky, and some real doubt was fostered when I realized that there are two different types of superposition that seem to be used synonymously in conversation, when they're not.

In other words, I began to suspect that it was an equivocation, and this is pretty solid evidence of that.
WriterDave
Posts: 934
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6/4/2012 11:37:46 PM
Posted: 4 years ago
At 6/4/2012 7:04:31 PM, Wnope wrote:
At 6/4/2012 4:00:29 PM, WriterDave wrote:
At 6/4/2012 2:06:41 PM, Wnope wrote:
I had a thought.

Couldn't the cat and box themselves lead to decoherence of the superposition even without someone observing?

According to the Objective Collapse interpretation, in which the wave function collapses when it meets or exceeds a particular physical threshold, yes. I'm not sure how many people subscribe to that interpretation, though.

What's the popular version these days? That we perceive wave collapse but it does not actually happen in an objective sense?

AFAIK, Copenhagen and Many-Worlds are the top two contenders these days. But I'm not aware of any polling on the subject among physicists. :-)
Writer. Liberal atheist. Official "Official of the FREEDO Bureaucracy" of the FREEDO Bureaucracy.

Edit To Civilize, with FAQs: http://bit.ly...
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mattrodstrom
Posts: 12,028
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6/5/2012 5:00:43 AM
Posted: 4 years ago
At 6/4/2012 10:04:14 AM, Thaumaturgy wrote:
go buy a dog. A MUCH better pet.

hey, hey, hey... you mean a much Different pet.

Cats are cool too. just different.

If you went away for vacation for a week or two and left your dog outside when you came back it'd either be half dead or replaced with a summons by ASPCA..

when I was little and we'd leave the cat out we'd come back and my cat'd be fat and happy (granted, we have more birds and squirrels around since he's been dead)
"He who does not know how to put his will into things at least puts a meaning into them: that is, he believes there is a will in them already."

Metaphysics:
"The science.. which deals with the fundamental errors of mankind - but as if they were the fundamental truths."
mattrodstrom
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6/5/2012 5:01:57 AM
Posted: 4 years ago
At 6/5/2012 5:00:43 AM, mattrodstrom wrote:
when I was little and we'd leave the cat out we'd come back and my cat'd be fat and happy (granted, we have more birds and squirrels around since he's been dead)

we did have the neighbor put food on our back porch.. but she said he never ate it :/
"He who does not know how to put his will into things at least puts a meaning into them: that is, he believes there is a will in them already."

Metaphysics:
"The science.. which deals with the fundamental errors of mankind - but as if they were the fundamental truths."
tBoonePickens
Posts: 3,266
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6/5/2012 10:50:59 AM
Posted: 4 years ago
At 6/4/2012 7:03:32 PM, Wnope wrote:
At 6/4/2012 2:52:08 PM, tBoonePickens wrote:
Can one actually observe a superposition?
Perhaps not, but from what little I know, aren't there certain conditions that don't involve interference from an agent (such a higher temperatures) which influence coherence?
If I am not mistaken it's actually the COLDER temps that do this; unless I am not understanding you correctly.

At higher temps, the distinct constituents of matter separate and group themselves into the 4th state of matter: plasma. This state closely resembles the initial state (Alpha State) of the early Universe: all electrons go to one side and all the protons to the other (a Grouping Order extreme.)

Contrast this with matter at extremely low temps: distinct constituents of matter merge grouping themselves into the 5th state of matter: BEC. This state closely resembles the final state (Omega State) of the Universe: all the atoms in the BEC become a singular thing (a Symmetry Order extreme.) Once the Universe reaches the Omega State (absolute zero), all things within the Universe will loose any distinction between each other; thus becoming a singular undivided whole.

I've come across "Consistent Histories" interpretation, and I have to say it is much more satisfying than Copenhagen. What are your feelings on it (Ren or tboone)?
It's funny you should say that, as I was reviewing all of the QM interpretations listed in Wiki...and then my head started to hurt!

I did skim the Consistent Histories, and also find it preferable over Copenhagen. What aspects of it curry favor with you?

I can tell you which interpretation is my preferred interpretation: de Broglie–Bohm theory. It is a hidden variable theory that satisfies Bell's Inequality by denying locality...and that's where it get's me: non-locality. It's a tough one to reconcile! I think Didn't Einstein refused to give up locality in his view of QM?

*****************************************

At 6/4/2012 7:26:51 PM, Ren wrote:
At 6/4/2012 2:52:08 PM, tBoonePickens wrote:
Can one actually observe a superposition?

Actually, yes.
Nah ah. Contradictions cannot exist!

It's been macrocosmically observed on a couple of occasions, usually involving electrical currents through mismatched conductors, for example: http://www.nature.com...
"...there has been no experimental demonstration of a quantum superposition of truly macroscopically distinct states."
Quote from your own link!

Kind of solidified the stance that physicists are most often accepting nowadays.
Try again.

**************************************************

At 6/4/2012 9:53:04 PM, Thaumaturgy wrote:
Superposition apparently falls out of the mathematics. Apparently superposition is an outcome of the nature of the Schroedinger equation which is "linear" and as such any "linear combination of solutions" to it will also be a solution to the equation.
Don't know what you mean by falls out of mathematics.

So it is a necessary part of the math, not necessarily something someone "observed".
In other words: it's necessary on paper but not in reality. That was my point.

Also remember that antimatter was something that fell out of Dirac's equation and it later was found to be real.
Ah yes! Back in the days when theories actually predicted stuff! However, I don't think that this is an apt analogy because antimatter isn't (and wasn't) a contradiction like superposition is.

Not sure if one "falsifies" a mathematical relationship.
I am not sure I understand you, and I think that you may not have understand me. To clarify: superposition (ie something that is in 2 mutually exclusive states simultaneously) is UNOBSERVABLE because once observed it (wave function) collapses into a singular outcome (ie no contradiction.) Ergo, one could NEVER observe a superposition because the act of observing it (ie measuring it) causes it NOT to be a superposition. It is unverifiable because there is no way to verify that there actually is a superposition.

Why does this matter?

(A) In a way it really doesn't matter because falsifiability isn't really a requirement in Physics (ie the Universe doesn't care.)

(B) Superposition, like so many things quantum (virtual particles, etc.), is only necessary on paper but not in reality. Full circle back to my point!
WOS
: At 10/3/2012 4:28:52 AM, Wallstreetatheist wrote:
: Without nothing existing, you couldn't have something.
Ren
Posts: 7,102
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6/5/2012 11:19:12 AM
Posted: 4 years ago
At 6/5/2012 10:50:59 AM, tBoonePickens wrote:

"...there has been no experimental demonstration of a quantum superposition of truly macroscopically distinct states."
Quote from your own link!

Kind of solidified the stance that physicists are most often accepting nowadays.
Try again.

???

That was a statement of need -- a gap in the research. They follow that by stating:

"...there has been no experimental demonstration of a quantum superposition of truly macroscopically distinct states. Here we present experimental evidence that a superconducting quantum interference device (SQUID) can be put into a superposition of two magnetic-flux states: one corresponding to a few microamperes of current flowing clockwise, the other corresponding to the same amount of current flowing anticlockwise."

This research is meant to fill that gap, thereby rendering proof that superposition is not purely quantum or theoretical.
tBoonePickens
Posts: 3,266
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6/5/2012 12:55:42 PM
Posted: 4 years ago
At 6/5/2012 11:19:12 AM, Ren wrote:
"Although much progress has been made in demonstrating the macroscopic quantum behavior of various systems such as superconductors, nano-scale magnets, laser-cooled trapped ions, photons in a microwave cavity and C60 molecules, there has been no experimental demonstration of a quantum superposition of truly macroscopically distinct states. Here we present experimental evidence that a superconducting quantum interference device (SQUID) can be put into a superposition of two magnetic-flux states: one corresponding to a few microamperes of current flowing clockwise, the other corresponding to the same amount of current flowing anticlockwise."

This research is meant to fill that gap, thereby rendering proof that superposition is not purely quantum or theoretical.
Naha, magnetic flux states are NOT macroscopic.
WOS
: At 10/3/2012 4:28:52 AM, Wallstreetatheist wrote:
: Without nothing existing, you couldn't have something.