Schrodinger's cat

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Schrodinger's cat

Postby ajjbotes on April 19th, 2017, 3:29 pm 

Hi. I recently came across mention of Schrodinger's cat and I have a lot of questions. Where can I read up on the topic in more or less plain english? I last touched Physics 101 35 years ago. Physics aside, I must say the version I heard did not seem logical.
Thanks for the help.
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Re: Schrodinger's cat

Postby Braininvat on April 19th, 2017, 9:04 pm 

That was actually Schrodinger's point: that the cat could not exist in two distinct states at the same point, and that this superposition of macro-scale objects was plain ridiculous. Schrodinger made up the thought experiment to poke fun at the Copenhagen interpretation of quantum physics. Try this link.....

http://www.iflscience.com/physics/schr%C3%B6dinger%E2%80%99s-cat-explained/
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Re: Schrodinger's cat

Postby ajjbotes on April 20th, 2017, 4:06 am 

Thanks for the link, it clarified a lot. Now however, I'd like to know why , at the quantum level(?), the argument of superposition is true.
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Re: Schrodinger's cat

Postby handmade on May 17th, 2017, 8:03 am 

Braininvat » April 19th, 2017, 8:04 pm wrote:That was actually Schrodinger's point: that the cat could not exist in two distinct states at the same point, and that this superposition of macro-scale objects was plain ridiculous. Schrodinger made up the thought experiment to poke fun at the Copenhagen interpretation of quantum physics. Try this link.....

http://www.iflscience.com/physics/schr%C3%B6dinger%E2%80%99s-cat-explained/



I know you might not want to hear this but I am sorry to say the whole thought experiment of the cat in the box is observer affect and does not mean anything but subjective imagination. Firstly the cat is placed in the dangerous situation , the box is designed to make a subjective awkward scenario setup. If the box was transparent there is no question is the cat alive or dead in the box.
We make predictions because our ''box'' we occupy is transparent.
The box in the cat scenario represents darkness, darkness removes any visual observation.


The cat in the box is alive and dead at the same time, why? because we can not see the cat.
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Re: Schrodinger's cat

Postby handmade on May 17th, 2017, 8:09 am 

ajjbotes » April 20th, 2017, 3:06 am wrote:Thanks for the link, it clarified a lot. Now however, I'd like to know why , at the quantum level(?), the argument of superposition is true.

It is about uncertainty, things we can't see like the cat in the box we can't be 100 percent certain of.
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Re: Schrodinger's cat

Postby ajjbotes on May 17th, 2017, 8:19 am 

Re: Schrodinger's cat

New postby handmade on May 17th, 2017, 3:03 pm

Braininvat » April 19th, 2017, 8:04 pm wrote:
That was actually Schrodinger's point: that the cat could not exist in two distinct states at the same point, and that this superposition of macro-scale objects was plain ridiculous. Schrodinger made up the thought experiment to poke fun at the Copenhagen interpretation of quantum physics. Try this link.....

http://www.iflscience.com/physics/schr%C3%B6dinger%E2%80%99s-cat-explained/




I know you might not want to hear this but I am sorry to say the whole thought experiment of the cat in the box is observer affect and does not mean anything but subjective imagination. Firstly the cat is placed in the dangerous situation , the box is designed to make a subjective awkward scenario setup. If the box was transparent there is no question is the cat alive or dead in the box.
We make predictions because our ''box'' we occupy is transparent.
The box in the cat scenario represents darkness, darkness removes any visual observation.


The cat in the box is alive and dead at the same time, why? because we can not see the cat.

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Alright. But without getting too technical, being alive excludes being dead. Box or no box, the cat cannot be both at the same time. All that the box accomplishes is hiding the cat from (normal) sight so that we cannot easily tell (with sight), whether the cat is alive or dead. It is what it is. Our (in)ability to determine status does not influence the status at all.
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Re: Schrodinger's cat

Postby handmade on May 17th, 2017, 8:52 am 


Alright. But without getting too technical, being alive excludes being dead. Box or no box, the cat cannot be both at the same time. All that the box accomplishes is hiding the cat from (normal) sight so that we cannot easily tell (with sight), whether the cat is alive or dead. It is what it is. Our (in)ability to determine status does not influence the status at all.


I assure you when this scenario was devised , they did not have our means of technological achievements. We have all sort of ways now that we could tell if the cat was dead or alive. Remember these type things were wrote years ago by ''small minded'' science and not of the now technology days.
It is not the point to show whether the cat is dead or alive though, it is just the point of showing uncertainty. However I can now be certain the cat is dead or alive by using modern technology to ''see''.

I would not spend to much time wrapped up in these type scenarios, they are pretty ''crappy'' and easily to show problems with them .
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Re: Schrodinger's cat

Postby bangstrom on May 18th, 2017, 4:09 am 

handmade » May 17th, 2017, 7:52 am wrote:
I assure you when this scenario was devised , they did not have our means of technological achievements. We have all sort of ways now that we could tell if the cat was dead or alive. Remember these type things were wrote years ago by ''small minded'' science and not of the now technology days.
It is not the point to show whether the cat is dead or alive though, it is just the point of showing uncertainty. However I can now be certain the cat is dead or alive by using modern technology to ''see''.

I would not spend to much time wrapped up in these type scenarios, they are pretty ''crappy'' and easily to show problems with them .

Contrary to some opinions expressed so far, the tale of Schroedinger’s cat is still very much alive and we now have the technology to test the veracity of its bizarre implications. Modern experiments support the quantum view over that of the classical ‘common sense’ interpretation demonstrated by the cat in the box scenario. Experiments have demonstrated that quantum systems remain in superposition until observed or interacted upon by the external world, at which time the superposition is forced into one or another of the possible definite states. So Schroedinger’s cat is both dead and alive until observed.

Objects in the macro world, like cats, do not behave the same as individual particles because everyday objects consist of countless billions of particles so we only see average effects.

“Do not keep saying to yourself, if you can possibly avoid it, "But how can it be like that?" because you will get "down the drain", into a blind alley from which nobody has yet escaped. Nobody knows how it can be like that.”- Richard Feynman
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Re: Schrodinger's cat

Postby ajjbotes on May 18th, 2017, 6:51 am 

I still fail to see how observation determines status/outcome/whatever. What precisely is observation in this context?
Say that (continuing with the cat in a box example) there is a camera recording the cat inside the box. Would that then determine the alive/dead status of the cat?. What if nobody sees the footage on the camera? Once again, what precisely counts as observation?
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Re: Schrodinger's cat

Postby Braininvat on May 18th, 2017, 9:34 am 

When a quantum system is not perfectly isolated from other particles, quantum decoherence occurs. This means a system as complex as a cat in a box cannot maintain a state of superposition. Please ignore Handmade's posts.

https://en.m.wikipedia.org/wiki/Quantum_decoherence

In other words, the box is self-observing. Even if the bit of radioisotope only interacted with another particle, it would decohere.

Schrodinger's thought experiment has passed its freshness date.
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Re: Schrodinger's cat

Postby ajjbotes on May 18th, 2017, 11:51 am 

Okay, now without me tackling a quantum physics handbook, give me an example where superposition does occur, and what makes us think that it does.? Why is no other explanation possible?
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Re: Schrodinger's cat

Postby Braininvat on May 18th, 2017, 12:38 pm 

Paging mitchellmckain, who is better equipped to answer such questions.
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Re: Schrodinger's cat

Postby bangstrom on May 19th, 2017, 4:47 am 

Braininvat » April 19th, 2017, 8:04 pm wrote:That was actually Schrodinger's point: that the cat could not exist in two distinct states at the same point, and that this superposition of macro-scale objects was plain ridiculous. Schrodinger made up the thought experiment to poke fun at the Copenhagen interpretation of quantum physics. Try this link.....

http://www.iflscience.com/physics/schr%C3%B6dinger%E2%80%99s-cat-explained/

Braininvat » May 18th, 2017, 8:34 am wrote:When a quantum system is not perfectly isolated from other particles, quantum decoherence occurs. This means a system as complex as a cat in a box cannot maintain a state of superposition. Please ignore Handmade's posts.

https://en.m.wikipedia.org/wiki/Quantum_decoherence

In other words, the box is self-observing. Even if the bit of radioisotope only interacted with another particle, it would decohere.

Schrodinger's thought experiment has passed its freshness date.


Review your link again. It implies nothing about the Schroedinger’s thought experiment being “past its freshness date” and Schroedinger’s cat is still relevant because it cautions how actions on the atomic scale do not behave the same as actions on the macro scale.

http://www.iflscience.com/physics/schr% ... explained/


The article says, “While it is true that modern experiments have revealed that while quantum superposition does work for tiny things like electrons, larger objects must be regarded differently.”

Decoherence would be a major problem if anyone tried to perform Schroedinger’s experiment for real but that misses the point. Nothing about the experiment is intended to be real any more than Einstein’s trains moving at relativistic speeds.

That is not to say that decoherence is not a serious problem in all experiments involving entangled particles and superposition. It is hard to demonstrate entanglement and to demonstrate that it has been maintained over the distance of an experiment. This limits the distance of an experiment and, if I recall, the long distance record is now about 100 km which is good but disappointing considering that entanglement can theoretically span the visible universe.

The above article also links to a video from “Sixty Symbols.”
https://www.youtube.com/watch?v=CrxqTtiWxs4

If you follow this video to the end it explains how the Copenhagen interpretation, mocked by Schroedinger, gives an accurate account of how matter behaves at the quantum level and superposition is an observable effect. It states near the end of the video, “We have done experiments and, at the quantum level, that’s how matter behaves.”
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Re: Schrodinger's cat

Postby bangstrom on May 20th, 2017, 7:17 am 

ajjbotes » May 18th, 2017, 10:51 am wrote:Okay, now without me tackling a quantum physics handbook, give me an example where superposition does occur, and what makes us think that it does.? Why is no other explanation possible?

I don’t know of any easy to understand examples of superposition that make sense without going into a bit more than the usual amount of detail but examples of quantum teleportation involve superposition states and more depth than examples of superposition alone so examples of teleportation may be a better place to start. Also, quantum teleportation is likely to become a useful tool in computer design so it is more than a curiosity.

I found this video that explains quantum teleportation.
http://www.popularmechanics.com/science ... ion-works/

My impression of the video is that it appears to have been written by someone with a strong mathematical background trying to explain teleportation without the math. It still looks like math to me and may appeal to the mathematodes but I find it overly complex. Given time, I can try to present a simpler (for me) narrative explanation of teleportation. Still the video does give a clear explanations for some of the important points.

Other explanations for superposition are possible but the Copenhagen interpretation is the most likely the best. The “Many-Worlds” interpretation is another explanation. It is too speculative for most but SF writers love it. Cramer’s Transactional Interpretation is my personal favorite and that’s another story.
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