I don't get Shrodinger's cat scenario, or by extension, quantum physics.

[skimple]

"Well, some researchers were once conducting such an experiment, but when they opened up the box, the cat was nether alive nor dead, but was in fact completely missing, and they called me to investigate. I was able to deduce that nothing very dramatic had happened. The cat had merely got fed up with being repeatedly locked up in a box and occasionally gassed and had taken the first opportunity to hoof it through the window. It was for me the work of a moment to set a saucer of milk by the window and call 'Bernice' in an enticing voice - the cat's name was Bernice you understand -"

Dirk Gently

 

[GagHalfrunt]

The problem with Schrödinger's cat is that Schrödinger never meant it as a real thought experiment. It was a sarcastic parody of what he felt were the problems with how scientists were approaching quantum mechanics at the time. After it gained traction and got to be viewed as a real thing he was sorry he ever came up with it.

 

[SlitheryDee]

It doesn't make sense because the cat itself should be an observer. It knows whether it's alive or dead, so it can't be in both states.

It works if it's stipulated in the scenario that in this case the cat is not an observer, just for the purposes of the thought experiment.

 

[ImpulsE69]

All I know is that cat better not piss in the trunk. You'll never get that smell out.

 

[Paratus]

 

[Jaskalas]

Ok, whatever. Maybe the measuring device is somehow affecting the state of the photon before it reaches the slit, which explains the differences in patterns.

Yeah, I thought the same thing. It's an obvious conclusion.
Then comes along The Quantum Eraser experiment which claims the "effect" can happen before the "cause". It breaks all logic and reason.

Perhaps the Quantum Eraser does not show us the breaking of time... but merely of space. What if the photon has some property or.. element of itself that instantly reaches its destination? Or... at least move fast enough to appear "instant" in such a small space as our experiment. Thereby, our intent to observe it with a delay is broken.

I propose that the photon actually interacts with the observer at any point along its path BEFORE it reaches the double slit.

 

[SMOGZINN]

It doesn't make sense because the cat itself should be an observer. It knows whether it's alive or dead, so it can't be in both states.

It works if it's stipulated in the scenario that in this case the cat is not an observer, just for the purposes of the thought experiment.

Yes, the cat is a non-observer object for this thought experiment. Sometimes this thought experiment is rephrased as a sandwich. You have to eat the sandwich to know if it has been poisoned or not.

 

[GagHalfrunt]

Yes, the cat is a non-observer object for this thought experiment. Sometimes this thought experiment is rephrased as a sandwich. You have to eat the sandwich to know if it has been poisoned or not.

C'mon, think this through. If you thought there was a 50/50 chance that the sandwich was poisoned you would not eat it to check. You'd get somebody else to eat it.

 

[ioni]

In a real life situation you'd also know the cat is dead when it stops meowing and clawing at the box.

No, he's not dead. He's sleepin.

 

[Charmonium]

Then comes along The Quantum Eraser experiment which claims the "effect" can happen before the "cause". It breaks all logic and reason.

If you've ever heard of Bell's Theorem, it proves that any system of quantum mechanics has to either violate locality (local causality) or counterfactual definiteness (close the refrigerator door but light is still on).

QM has been repeatedly shown to violate locality.

 

[flopper]

Sooo... the idea is that there's a cat in a box with some poison that could be released at any random time. Until we look inside the box, we don't know if the cat is alive or dead. Thus, when it is in the box, it can exist in two superimposed states, both alive and dead.

I totally don't get this. It seems to me that saying the cat is BOTH alive and dead is simply a way for us to say that we have no idea what's actually going on. We don't *know*.

What's actually going on is that the cat is actually in one of two states, alive or dead. Just because we don't *know* what state it's in doesn't mean that it's *not* in one of these two states. Opening the box and observing it shouldn't magically force it into being in one of two states.

Like... just because we don't know precisely how much fossil fuel we have left on this planet doesn't mean that there isn't a precise amount. It's just that we don't know. We don't know the exact coordinates of a bird flying overhead as we speak, but that doesn't mean that a bird's *not* there, flying overhead, at a certain coordinate. We just don't know about it.

Considering that I don't get this, I have a hard time wrapping my head around quantum mechanics and quantum computing. A single quantum bit (qubit) can be in multiple states at the same time instead of a 0 or a 1, like a classical bit. But how does this make sense? To me, all it means is we have no way of knowing what state it is actually in. It's still in a certain state at any point in time, we just don't know what it is. In quantum computing, how is it possible to use our complete lack of information to do actual computing?

issue one, your using conceptual thinking on quantum states.
comparing the analogy of a quantum state vs a cat in a box = failed thinking.
The cat is always dead especially 90 years later.

quantum states can hold more information than one and zero, so this requries you to think differently about the quantum state vs an actual computers way to process information.
cant think the same way about a quantum state computer as you do with current technology.

 

[mikeymikec]

No, he's not dead. He's sleepin.

Or the cat is waiting for someone to open the box and claw their face off in revenge.

 

[Charmonium]

Zombie kitty is both dead and alive

38 posts and no one thought of this? Son, I am disappoint.

 

[SMOGZINN]

C'mon, think this through. If you thought there was a 50/50 chance that the sandwich was poisoned you would not eat it to check. You'd get somebody else to eat it.

That all matters on the type of sandwich...

 

[poofyhairguy]

The cat's well-being depends on the state of the atom (50% chance it decayed in a certain time), and QT proved (double slit experiment etc.) that atoms have no (better: take on a) "real" state UNLESS, and only then, once we look at it.

So if we can't observe the behavior and know what is going on what can we know for certain? If we can never confirm or deny any part of it, we are just as ignorant as when we began to seek the knowledge right?

I must be missing the point because what I understand from what you said is "don't waste your time studying quantum physics because humans can't know anything about the state of the atom with certainty anyway." Obviously that isn't the point (because people are studying it) so I feel a little lost.

 

[Humpy]

It makes me sad that there could be a dead/dying cat in a box.

 

[IronWing]

Imagine the horrors to be visited upon humanity should cats develop particle-wave duality.

 

[WHAMPOM]

It is just a thought experiment used to show the paradox in quantum physics.

 

[flexy]

The problem with Schrödinger's cat is that Schrödinger never meant it as a real thought experiment. It was a sarcastic parody of what he felt were the problems with how scientists were approaching quantum mechanics at the time. After it gained traction and got to be viewed as a real thing he was sorry he ever came up with it.

You are right, but the silly parody *does* do a good job showing the problem reconciling QT with our reality. After all, everything is made from atoms/particles. How could we accept QT weirdness on a particle level but reject it as "impossible" in the macro world? So..either/or. We can't separate the two.

 

[flexy]

It doesn't make sense because the cat itself should be an observer. It knows whether it's alive or dead, so it can't be in both states.

It works if it's stipulated in the scenario that in this case the cat is not an observer, just for the purposes of the thought experiment.

This is of course correct too but then the cat in the box is an analogy and we shouldn't overthink the experiment.

But there are valid questions that arise:

* Is a (conscious) observer actually necessary to collapse the wave function, to "make" the cat dead or alive, the photon a particle or a wave?

*IF* (and only if) the reality is created by the observer, does it mean us, us humans as being the observer, or would the cat be sufficient? (Or a fly, or a bacterium etc., say that's in the box)

It basically comes down to the essential philosophical question whether there is a reality WITHOUT someone observing it?

--> It gets even more bizarre. We haven't even seen the tip of the iceberg of QT weirdness.-***

Yesterday I read something that we, by observing cosmic background radiation, have CREATED (!) the Big Bang and the universe.

Never afraid to make the grand intuitive leap (remember his vision of the single electron weaving its way through space and time), Wheeler goes on to consider the whole universe as a participatory, self-excited circuit.

Starting from the Big Bang, the universe expands and cools; after thousands of millions of years it produces beings capable of observing the universe, and “acts of observer-participancy—via the mechanism of the delayed-choice experiment—in turn give tangible ‘reality’ to the universe not only now but back to the beginning.”

By observing the photons of the cosmic background radiation, the echo of the Big Bang, we may be creating the Big Bang and the universe. If Wheeler is correct, Feynman was even closer to the truth than he realized when he said that the two-hole experiment “contains the only mystery.”

Similar there are scientists who speculate that we accelerated the death of the universe by observing dark energy.

http://arstechnica.com/uncategorize...gy-may-shorten-the-life-span-of-the-universe/

 

[DrPizza]

More helpful:

https://www.youtube.com/watch?v=DfPeprQ7oGc

(Just ignore that the interference pattern doesn't align with the constructive and destructive interference of the waves. )

Ok, so to sum up the observations from the double slit experiment:

There, that wasn't so hard, was it? That's what the mathematics says should happen, and that's what happens when you do it experimentally. Reality's a bitch to figure out, isn't it.

 

[SMOGZINN]

*IF* (and only if) the reality is created by the observer, does it mean us, us humans as being the observer, or would the cat be sufficient? (Or a fly, or a bacterium etc., say that's in the box)

A more interesting question is if you have observed the state and made the wave function collapse, has it collapsed for me?

 

[Charmonium]

A more interesting question is if you have observed the state and made the wave function collapse, has it collapsed for me?

I wouldn't take the Copenhagen/Bohr interpretation too literally. Collapsing the wave function is just short hand for the fact that a particle enters its pure state (with respect to a particular measurement). Other interpretations are Everet's many worlds and de Broglie's pilot waves. The bottom line is that QM is too weird to allow us to have any conceptual analogs.

 

[disappoint]

Yeah, I thought the same thing. It's an obvious conclusion.
Then comes along The Quantum Eraser experiment which claims the "effect" can happen before the "cause". It breaks all logic and reason.

Perhaps the Quantum Eraser does not show us the breaking of time... but merely of space. What if the photon has some property or.. element of itself that instantly reaches its destination? Or... at least move fast enough to appear "instant" in such a small space as our experiment. Thereby, our intent to observe it with a delay is broken.

I propose that the photon actually interacts with the observer at any point along its path BEFORE it reaches the double slit.

Photons do not experience time. They never travel through the time dimension. From the perspective of the photon, there is no time dimension.

 

[blankslate]

:awe:

_________