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Ricky
SFN Die Hard
USA
4907 Posts |
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Dave W.
Info Junkie
USA
26022 Posts |
 Posted - 06/10/2005 : 20:30:01 [Permalink]
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quote:
Originally posted by woolytoad
Well, w.r.t the cat in particular, yes is it mostly just a math thing. But superposition of states do occur.
Oh, no, I agree that superpositions of states do occur, on a quantum level, but not to the cat itself.quote:
Take Young's double slit experiment. You will still get the diffraction pattern if you used a light source so dim that only a single photon was shot towards the slits at one time. Which shows that a single photon goes through both slits! Young's experiment carried out with detectors inside the slits, will result in no interference pattern. The act of making a measurement will change the quantum state of the system we want to measure!
Technically, no: the act of moving the detectors changes the system we want to measure so that the quantum states in one have little relation to the quantum states in the other. With detectors at the slits, the photons cannot interfere with themselves.
Of course, the double-slit experiments point out the dual wave/particle nature of particles, whereas Schrodinger's Cat points out the effect of observation (correctly defined, you're right, as "any interaction," despite what the "God as universal observer" proponents want to hear) on the wave function. Two different things.
By the way, Giltwist, if the cat decided to take a nap during the experiment, gravity won't be noticably affected by its death. Not that I know many cats which would be calm enough trapped in a box to sleep, but you never know. The point being: a change in the center of gravity of the experiment would not be a reliable "death detector." |
- Dave W. (Private Msg, EMail)
Evidently, I rock!
Why not question something for a change?
Visit Dave's Psoriasis Info, too. |
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H. Humbert
SFN Die Hard
USA
4574 Posts |
Posted - 06/10/2005 : 20:42:32 [Permalink]
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quote:
Originally posted by Dave W.
quote:
Originally posted by woolytoad
Well, w.r.t the cat in particular, yes is it mostly just a math thing. But superposition of states do occur.
Oh, no, I agree that superpositions of states do occur, on a quantum level, but not to the cat itself.
Yeah, perhaps it was unclear what I was arguing.
I can accept that photons, etc. can exist in mulitple localities or "states." My only problem is when this fact of nature is somehow extrapolated to the universe writ large.
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"A man is his own easiest dupe, for what he wishes to be true he generally believes to be true." --Demosthenes
"The first principle is that you must not fool yourself - and you are the easiest person to fool." --Richard P. Feynman
"Face facts with dignity." --found inside a fortune cookie |
| Edited by - H. Humbert on 06/10/2005 20:45:37 |
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Giltwist
Skeptic Friend
USA
69 Posts |
Posted - 06/10/2005 : 20:47:36 [Permalink]
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quote:
a change in the center of gravity of the experiment would not be a reliable "death detector."
Granted, but on that principle you'd think you'd be able to create a system that was without ever have to involve the sort of active sonar method described with the tennis balls. Wouldn't that just blow the socks off Heisenburg? If you could passively monitor by gravity, you would be able to get both position and velocity, wouldn't you? |
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Dude
SFN Die Hard
USA
6891 Posts |
Posted - 06/10/2005 : 21:00:43 [Permalink]
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Gravity will probably play a major role in answering some of the questions that remain concerning quantum physics.
I read a recent article that suggested the reason why larger objects don't readily demonstrate superposition states (the way a photon does with the double slit) is that interaction with gravity forces the collapse of the wave function much more rapidly, preventing the observation of interference.
I'm not sure if I'm explaining that right, but the article was in Discover magazine.
http://www.discover.com/issues/jun-05/cover/
Interesting read.
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Ignorance is preferable to error; and he is less remote from the truth who believes nothing, than he who believes what is wrong.
-- Thomas Jefferson
"god :: the last refuge of a man with no answers and no argument." - G. Carlin
Hope, n.
The handmaiden of desperation; the opiate of despair; the illegible signpost on the road to perdition. ~~ da filth |
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H. Humbert
SFN Die Hard
USA
4574 Posts |
Posted - 06/10/2005 : 21:08:06 [Permalink]
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Ah, thanks, Dude! That was the article I was talking about.
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"A man is his own easiest dupe, for what he wishes to be true he generally believes to be true." --Demosthenes
"The first principle is that you must not fool yourself - and you are the easiest person to fool." --Richard P. Feynman
"Face facts with dignity." --found inside a fortune cookie |
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Dave W.
Info Junkie
USA
26022 Posts |
Posted - 06/10/2005 : 21:30:50 [Permalink]
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quote:
Originally posted by Giltwist
Granted, but on that principle you'd think you'd be able to create a system that was without ever have to involve the sort of active sonar method described with the tennis balls. Wouldn't that just blow the socks off Heisenburg? If you could passively monitor by gravity, you would be able to get both position and velocity, wouldn't you?
Gravity is thought to be carried by particles called gravitons. In other words, it also is "active sonar," since everything with mass emits and interacts with gravitons. |
- Dave W. (Private Msg, EMail)
Evidently, I rock!
Why not question something for a change?
Visit Dave's Psoriasis Info, too. |
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woolytoad
Skeptic Friend
313 Posts |
Posted - 06/11/2005 : 08:11:53 [Permalink]
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I am duly corrected by Dave. I am confusing some aspects of Young's experiment with SQUID experiments:
http://www.amherst.edu/~jrfriedman/Scientific%20American/scientific-american%20edited.html
quote:
Originally posted by H. Humbert
quote:
You can achieve a sufficient level of isolation to keep some quantum properties unaffected though.
Not sure what you mean here. Can you explain?
Ever looked up how a quantum computer works? Each qubit can exist as a 0, 1, or both 0 and 1. That is, a superposition of quantum states. As discussed previously, any sort of interaction is an observation. So how do you keep the superposition of states from collapsing? I don't know the entire answer, but IIRC, they use spin because its a little easier to keep isolated from things that would effect it. |
| Edited by - woolytoad on 06/11/2005 08:28:18 |
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