Schrödinger's Cat

[xcrissxcrossx]

Ever hear of Schrödinger's cat? A cat is placed in a sealed box. Attached to the box is an apparatus containing a radioactive atomic nucleus and a canister of poison gas. This apparatus is separated from the cat in such a way that the cat can in no way interfere with it. The experiment is set up so that there is exactly a 50% chance of the nucleus decaying in one hour. If the nucleus decays, it will emit a particle that triggers the apparatus, which opens the canister and kills the cat. If the nucleus does not decay, then the cat remains alive. According to quantum mechanics, the unobserved nucleus is described as a superposition (meaning it exists partly as each simultaneously) of "decayed nucleus" and "undecayed nucleus". However, when the box is opened the experimenter sees only a "decayed nucleus/dead cat" or an "undecayed nucleus/living cat."[/b] Basicly, the cat dies and stays alive at the same time. How do you think it works?

[Burns]

I've never been able to understand this. I mean, if the canister opens and kills the cat, it's dead whether someone sees it or not. Just like if a tree falls in the woods and there's no one around to hear it, it still makes a noise. I know it's all quantum theory and whatnot, but just because a human doesn't witness it, doesn't mean it doesn't happen. My hubby and I have gotten into so many arguments about that goddamned tree! lol

[xcrissxcrossx]

I've never been able to understand this. I mean, if the canister opens and kills the cat, it's dead whether someone sees it or not. Just like if a tree falls in the woods and there's no one around to hear it, it still makes a noise. I know it's all quantum theory and whatnot, but just because a human doesn't witness it, doesn't mean it doesn't happen. My hubby and I have gotten into so many arguments about that goddamned tree! lol [/b] I expected Burns to be the first one to post. But anyways i agree. especially about the tree. haha.

[Peregrinus]

From a previous thread in Philosophy: A fairly detailed discussion of quantum mechanical measurment and Schroedinger's Cat begins near the middle of pg. 1 The fact is that until we understand the nature of a quantum mechanical observation, no one can say with certainty whether the cat is collapsed into an alive or dead state before the box is opened or whether up until that moment, the cat, like the Geiger counter and the state of atomic decay, exists in a literal superposition of states, neither and both alive and dead. It's not the same as a tree falling in a forest. In quantum mechanics, before a system is observed, its collapsed state is not simply unknown, it is unknowable.

[Burns]

I was hoping Peregrinus would reply to this thread - she always has good explanations for this kind of stuff!

[Peregrinus]

Glad to help This post actually made me think of the cover of my old QM textbook, which quite explicitly illustrates Schroedinger's cat conundrum. Front cover: Kitty is alive and well. Back cover: Kitty has perished - a helpless victim of the unyielding quest for scientific knowledge. Opened front and back cover: Draw what conclusions you will. This is what happens when physicists get their hands on a ClipArt CD.

[Kaniaz]

The scary part is, what happens to the little post-it note we see in the first picture? Spooky goings on when you invoke the power of half-zombie cats. EDIT: And for those who like their finer arts, a (brief) explanation of quantum mechanics is provided in poem form.

[OpheliaBlue]

haha peri and Kaniaz

[Peregrinus]

The scary part is, what happens to the little post-it note we see in the first picture? Spooky goings on when you invoke the power of half-zombie cats.[/b] You know, I made a deal with the zombie cat when I got the book that he wouldn't start messing with the text, taking advantage of a superposition of states when the book was closed... but I guess he figured I only made that deal with the live half of him. Damn sneaky cat. And for those who like their finer arts, a (brief) explanation of quantum mechanics is provided in poem form. [/b] Well that's just about the best damn explanation of quantum mechanics I've ever read! If only they'd printed that in my textbook instead of all of those tedious partial differential equations...

[Tsen]

There's a T-Shirt about Schroedinger's Cat on thinkgeek.com ... Anyway, the real question is whether the cat counts as an observer or not--and precisely WHAT defines an observer. Anyway, for the most part, we really will have to wait until they do more research, since we can't settle the question by arguing about it.

[151]

This is a great example of education getting in the way of the obvious. Too bad quantum mechanics doesnt support itself very easily. By the way I wish smart people were more productive. Think of how wonderful it would be if we tackled lifes questions in proper order. 1. find food and water 2. cure cancer 3.decide if pluto is a planet 4.put a cat in a radioactive box Ok what I meant was life and death are not eigenstates. I think Schrödinger was just trying to make a point.

[Peregrinus]

Ok what I meant was life and death are not eigenstates. I think Schrödinger was just trying to make a point. [/b] Yes, he was trying to make a point, and no, life and death are not eigenstates. However, the state of decay of an atomic nucleus is an eigenstate, and because the cat is in a box with a vial of poison and decaying nucleus, its system state (alive or dead - a combination of the eigenstates of its constituent particles) becomes coupled with that of the nucleus. But really, the "point" of the whole hypothetical experiment was to question the nature of quantum mechanical observation. I think understanding the very nature of the physical universe is a fairly important and "productive" undertaking, but hey, if you think classifying rocks is more important, be my guest. The IAU could use a bit of help right now (BTW, is your SN a reference to rum - "But why is all the rum gone?! - or something else?)

[151]

I also think understanding the very nature of the physical universe is a fairly important and "productive" undertaking. I just believe the world would be better served if humanity had more focus and a better sense of urgency when setting its priorities. I would wager that many of the worlds best minds are hard at work this very second to discover the hidden truths of QM. If I was king O' the world I would request the great minds of our age solve some more pertinent problems. Such as cancer, making environmentally friendly energy sources financially beneficial to the world and so on and so forth. But what do I know. If "minds" were not allowed to work in a field they chose they might choose not to work at all. It could very well be true that our current system is by far the best. I still wouldnt mind being King o' the world sorry I forgot, 151 is my off road motorcycle racing number. I do like a good mohito though Here is an interesting tid bit. At this point you "peregrinus" have 151 post in the philosophy forum!

[Slight]

I have this book of Stephen Hawking, in which he explains the example. He claims, that philosophers are holding on to the classical term of reality - an object can only have one specific history. Quantuum mechanics now "offers", that an object can not only have one history, but all that are possible. Most of the time the probability of having one specific history wipes out the probability of having another. But in some cases the two probabilities empower each other; like in Schroedinger's cat experiment, where the cat is dead and alive at the same time - those two historys can exist next to each other; because quantuum mechanics "allows" an object to have all historys possible. Now - I still don't get it.

[Peregrinus]

I just believe the world would be better served if humanity had more focus and a better sense of urgency when setting its priorities. Such as cancer, making environmentally friendly energy sources financially beneficial to the world and so on and so forth. [/b] Despite my above, slightly snarky remark about the IAU and rock classification, I do know what you mean, although I still hold that pure physics is a worthy pursuit. The fact that it doesn't concretely benefit the suffering masses of humanity or immediately contribute to solving the vast social, political, economic, and environmental problems which we have with such blind persistence created for ourselves over the entire course of our history is actually the primary reason I decided not to pursue it with my graduate studies. In any case, regardless of a person's chosen profession, I believe that we all have an obligation to use our talents and skills to improve our environment (both social and natural) and the lives of those around us, whether through our work, hobbies, or charity. No one needs to be a savior or a saint - we all just have to get off of our asses once in a while and care. Here is an interesting tid bit. At this point you "peregrinus" have 151 post in the philosophy forum! [/b] But now I've ruined the symmetry Ok, did I just imagine wombing's drunken post, or did he delete it? (*Does RC, just in case*)

[wombing]

*laughs* i've come to realize that if i make a post and can't even remember what i just said, it's probably not worth polluting the net with. tis a habit i'm trying to break. hence the deletion about 30 seconds after i posted. your reply was much more concise and well-spoken anywho... -- oh, and SLIGHT, i love your sig.

[Peregrinus]

i've come to realize that if i make a post and can't even remember what i just said, it's probably not worth polluting the net with. tis a habit i'm trying to break. [/b] Fair 'nough.