Questions tagged [schroedingers-cat]
136 questions
55
votes
10 answers
Is Schrodinger's Cat itself an observer?
In Schrodinger's Cat thought experiment,
why doesn't the cat itself qualify as an observer?
Reading through the replies there seem to be two suggestions for what can take the role of observer:
any "large" body
any "living" thing (or should that…
Malcolm Storey
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54
votes
6 answers
Isn't the detector always measuring, and thus always collapsing the state?
I have a radioactive particle in a box, prepared so as to initially be in a pure state
$\psi_0 =1\ \theta_U+ 0\ \theta_D$
(U is Undecayed, D is Decayed).
I put a Geiger counter in the box.
Over time (t), the theory says that the state should evolve…
Juan Perez
- 3,082
47
votes
9 answers
Extension of Schrödinger's cat thought experiment
My question is quite simple. In the thought experiment of Schroedinger's cat: When the scientist measures the state of the cat, its wavefunction collapses into either the alive or dead state. But wouldn't then the scientist in turn be in a…
Loreno Heer
- 624
31
votes
7 answers
When will a wave function collapse if the observer was only a camera and the video was watched later in time?
If the only observer for the Schrödinger's cat experiment was a camera filming the box from the outside while the box was opened automatically without direct human intervention, and the only observation performed was through watching the recorded…
human
- 437
30
votes
12 answers
How can Schrödinger's cat be both dead and alive?
So, this goes to something so fundamental, I can barely express it.
The Schrödinger's Cat thought experiment ultimately asserts that, until the box is opened, the cat is both dead AND alive. Now, this is obviously ludicrous. The cat either died or…
White Prime
- 527
19
votes
4 answers
Schrödinger's cat; why was it necessary?
Could someone please explain to me the idea that Schrödinger was trying to illustrate by the cat in his box? I understand that he was trying to introduce the notion of the cat being both alive and dead at the same time. But why was it necessary to…
Sarah Jayne
- 625
17
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9 answers
What experimental proof of quantum superposition do we have?
My question is both naive and subtle. Naive because I don't know much more than the layman about physics and in particular quantum physics. Subtle because physics is an attempt to model the world, and as a computer scientist, with a strong interest…
b_habegger
- 287
13
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13 answers
Can I infer that Schrödinger's cat is dead without opening the box, if I wait a thousand years?
Say I have Schrödinger's cat in a sealed box. It is $\frac{1}{\sqrt{2}}\left(|dead\rangle+|alive\rangle\right)$.
Given that cats have a lifespan of ~20 years, if I wait a thousand years, I should be able to infer with 100% certainty that the cat is…
Allure
- 23,373
12
votes
7 answers
What counts as "observation" in Schrödinger's Cat, and why are superpositions possible?
So if I understood correctly, Schrödinger's Cat is a thought experiment that puts a cat inside a box, and there's a mechanism that kills the cat with 50% probability based on a quantum process. The argument is that the cat now must be in a…
ithisa
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Why is Schrödinger's cat in a superposition and not a mixture if you model decay with Fermi's golden rule?
I am teaching quantum information for undergraduate math students and as a perspective I thought it would be cool for them to discuss Schrödinger's cat a bit.
More precisely I'd like to come up with some explaination of how the cat gets to the…
12
votes
8 answers
Is the Copenhagen interpretation falsifiable?
According to the Copenhagen interpretation, physical systems generally do not have definite properties prior to being measured. The Schrödinger's cat is both dead and alive, until an observation is made.
Is this interpretation falsifiable? If it's…
asmani
- 530
10
votes
2 answers
Can Schrödinger's cat be revived?
According to Quantum Mechanics, Schrödinger’s cat is in a superposition state of $\frac{1}{\sqrt{2}}(\left|A\right> + \left|D\right>)$, where $\left|A\right>$ and $\left|D\right>$ correspond to alive and dead state respectively. An external observer…
wei
- 101
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Schrödinger's cat and the difficulty of macroscopic superposition state
The Schrödinger's cat was regarded as peculiar since we seldom encounter a superposition state in macroscopic scale: $$ \mid \mathrm{dead \,\,cat} \rangle + \mid \mathrm{alive \,\, cat}\rangle $$
We more often describe an unknown cat as
$$ \mid…
user26143
- 6,571
9
votes
3 answers
Determining the probability of outcomes in a measurement
While showing us the Schrodinger's cat experiment, my physics teacher defined:
$$\varphi_\text{alive} = \begin{bmatrix}1\\0\end{bmatrix},\qquad \varphi_\text{dead} = \begin{bmatrix}0\\1\end{bmatrix}, \qquad \hat{O}\varphi =…
user176139
- 93
9
votes
2 answers
How to check whether Schrödinger's cat was in superposition of states?
Suppose we can make an arbitrarily precise preparation of a Schrödinger's cat (and isolate it arbitrarily well so that decoherence is not a problem). If we prepare lots of cats in this state, what measurement can tell us whether these cats were in a…
Ruslan
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