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Physicists scoop information from Schrodinger's cat box [Quantum Mechanics]
Christian Science Monitor ^ | January 21, 2014 | Eoin O'Carroll

Posted on 01/22/2014 2:53:50 PM PST by ETL

In a paper published in the current issue of the scientific journal Nature Communications and titled "Direct measurement of a 27-dimensional orbital-angular-momentum state vector," a team of physicists led by the University of Rochester's Mehul Malik describe how they circumvented a basic principle of uncertainty that requires that some states of a quantum system must be understood poorly if other states are to be understood well.

Determining a quantum state, such as the position of an electron or the momentum of a photon, is tricky, to say the least. That's because subatomic particles behave nothing at all like billiard balls, orbiting moons, or any other kind of object with which we humans are remotely familiar.

A photon, for instance, sometimes acts like a wave, diffracting, interfering, and scattering, as all good waves ought to. Yet sometimes it will also behave like a particle, for instance by bashing into an electron or by traveling with ease through a vacuum.

According to our current understanding, things at the quantum scale can exist simultaneously in these two modes, both as localized particles, with distinct measurable states, and as spread-out probabilistic waves, with multiple contradictory states.

One consequence of this "wave-particle duality" is that it imposes a fundamental limit on how much we can know about the universe. An unobserved electron, say scientists, exists as a wave of mutually contradictory states. As the German physicist Werner Heisenberg first pointed out in 1927, taking a measurement of one state, say, the electron's position, and you irreversibly alter its momentum, and vice versa. In the parlance of quantum physicists, the "wavefunction" of a system's probabilities "collapses" into a specific state when you observe it.

If the quantum-mechanical model sounds bizarre, that's because it is.

(Excerpt) Read more at csmonitor.com ...


TOPICS: Science
KEYWORDS: erwinschrdinger; quantummechanics; schrodinger; schrodingerscat; schrodingerslitter; stringtheory; uncertaintyprinciple
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To: Leaning Right
Only when you observe the moon does it come into being in one place. All other possibilities become zero. So in this part of quantum mechanics, human observation really does change things!

OK... what happens when TWO or more people see it at the same time? then what???

61 posted on 01/22/2014 5:05:13 PM PST by Chode (Stand UP and Be Counted, or line up and be numbered - *DTOM* -vvv- NO Pity for the LAZY - 86-44)
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To: 6SJ7; AdmSmith; AFPhys; Arkinsaw; allmost; aristotleman; autumnraine; backwoods-engineer; ...
Thanks ETL.


· List topics · post a topic · subscribe · Google ·

62 posted on 01/22/2014 5:15:03 PM PST by SunkenCiv (;http://www.freerepublic.com/~mestamachine/)
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To: SunkenCiv
e=mChode2 suck at String Theory...
63 posted on 01/22/2014 5:19:03 PM PST by Chode (Stand UP and Be Counted, or line up and be numbered - *DTOM* -vvv- NO Pity for the LAZY - 86-44)
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To: Chode
OK... what happens when TWO or more people see it at the same time? then what???

I was waiting for that question, and I knew you would ask it! It is night. You are inside and cannot see the moon. So the moon "exists" everywhere it possibly could be, including in the sun.

I am outside. I am observing the moon. It is where I see it, and nowhere else.

So where is the moon? Some physicists say it's where I, the actual observer, see it. Others say that your interpretation is equally valid, and so the question can have no definite answer.

With large objects it does not matter. For you, the moon is everywhere, but it is most probably in its normal orbit, where I see it. For you, the chances of it being anywhere else are real, but very low. So you wouldn't complain too much about my observation.

But as objects become smaller, the chances of a far-away observation increases. If the moon were the size of an electron, there would be a decent chance that it would be observed in the sun, then an instant later past Mars, then an instant later in its normal orbit.

Weird stuff. As I mentioned earlier, Einstein could not accept it. And that's one reason he made almost no useful contributions to science in the last 25 years of his life.

64 posted on 01/22/2014 5:31:51 PM PST by Leaning Right (Why am I holding this lantern? I am looking for the next Reagan.)
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To: Leaning Right

It appears the question is how does the electron know what you are measuring for and why does the electron show up for the test exactly how you want to measure it? Why does the electron want to please the tester? Could it somehow be communicating with us?


65 posted on 01/22/2014 5:37:13 PM PST by Nuc 1.1 (Nuc 1 Liberals aren't Patriots. Remember 1789!)
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To: SunkenCiv

You’re welcome. Thanks for pinging your mob over here. :)


66 posted on 01/22/2014 5:39:03 PM PST by ETL (ALL (most?) of the Obama-commie connections at my FR Home page: http://www.freerepublic.com/~etl/)
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To: Chode

“In science, the term observer effect refers to changes that the act of observation will make on a phenomenon being observed. This is often the result of instruments that, by necessity, alter the state of what they measure in some manner. A commonplace example is checking the pressure in an automobile tire; this is difficult to do without letting out some of the air, thus changing the pressure. This effect can be observed in many domains of physics.

The observer effect on a physical process can often be reduced to insignificance by using better instruments or observation techniques.

Historically, the observer effect has been confused with the uncertainty principle.[1][2]”

http://en.wikipedia.org/wiki/Observer_effect_%28physics%29


67 posted on 01/22/2014 5:40:08 PM PST by ETL (ALL (most?) of the Obama-commie connections at my FR Home page: http://www.freerepublic.com/~etl/)
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To: Chode
"The theoretical foundation of the concept of measurement in quantum mechanics is a contentious issue deeply connected to the many interpretations of quantum mechanics. A key topic is that of wave function collapse, for which some interpretations assert that measurement causes a discontinuous change into an eigenstate of the operator associated with the quantity that was measured. More explicitly, the superposition principle (ψ = Σanψn) of quantum physics says that for a wave function ψ, a measurement will give a state of the quantum system of one of the m possible eigenvalues fn, n=1,2...m, of the operator \hat{F} which is part of the eigenfunctions ψn, n=1,2,...n.

Once we have measured the system, we know its current state and this stops it from being in one of its other states.[3] This means that the type of measurement that we do on the system affects the end state of the system. An experimentally studied situation related to this is the quantum Zeno effect, in which a quantum state would decay if left alone but does not decay because of its continuous observation. The dynamics of a quantum system under continuous observation is described by a quantum stochastic master equation known as the Belavkin equation.[4][5][6]

An important aspect of the concept of measurement has been clarified in some QM experiments where a small, complex, and non-sentient sensor proved sufficient as an "observer"—there is no need for a conscious "observer".[7]

A consequence of Bell's theorem is that measurement on one of two entangled particles can appear to have a nonlocal effect on the opposite particle. Additional problems related to decoherence arise when the observer too is modeled as a quantum system.

The uncertainty principle has been frequently confused with the observer effect, evidently even by its originator, Werner Heisenberg.[1] The uncertainty principle in its standard form actually describes how precisely we may measure the position and momentum of a particle at the same time — if we increase the precision in measuring one quantity, we are forced to lose precision in measuring the other.[8] An alternative version of the uncertainty principle,[9] more in the spirit of an observer effect,[10] fully accounts for the disturbance the observer has on a system and the error incurred, although this is not how the term "uncertainty principle" is most commonly used in practice."

http://en.wikipedia.org/wiki/Observer_effect_%28physics%29

68 posted on 01/22/2014 5:42:51 PM PST by ETL (ALL (most?) of the Obama-commie connections at my FR Home page: http://www.freerepublic.com/~etl/)
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To: ETL

Please ping me to the Quantum Mechanics / pix of cats in boxes threads!


69 posted on 01/22/2014 6:26:34 PM PST by palmer (Obama = Carter + affirmative action)
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To: Nuc 1.1
why does the electron show up for the test exactly how you want to measure it? Why does the electron want to please the tester?

Fascinating questions. Delightful even. And fun to think about. But sadly, it would take someone well above my pay grade to answer them.

70 posted on 01/22/2014 6:37:01 PM PST by Leaning Right (Why am I holding this lantern? I am looking for the next Reagan.)
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To: Chode

Awww, had a collapse of the wave function?


71 posted on 01/22/2014 7:15:03 PM PST by MHGinTN (Being deceived can be cured.)
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To: ETL

Thanks for the ping!


72 posted on 01/22/2014 7:18:59 PM PST by Alamo-Girl
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To: MHGinTN
LOL!!! pretty much...
73 posted on 01/22/2014 7:22:17 PM PST by Chode (Stand UP and Be Counted, or line up and be numbered - *DTOM* -vvv- NO Pity for the LAZY - 86-44)
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To: Bobalu
Thanks for posting the pics! My favorite...

 

74 posted on 01/22/2014 7:44:00 PM PST by zeugma (Is it evil of me to teach my bird to say "here kitty, kitty"?)
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To: Chode
but checking the pressure of a tire is a MEASUREMENT not an observation, LOOKING a tire and seeing it is soft is an observation...

Now, this is an interesting parallel to the question... When you take the pressure of a tire, air escapes, so the pressure you get is different from the pressure that was in it before you measured it.

75 posted on 01/22/2014 7:46:25 PM PST by zeugma (Is it evil of me to teach my bird to say "here kitty, kitty"?)
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To: zeugma
there you go... better check it again to see how much air you let out to check it! repeat as necessary 8^)
76 posted on 01/22/2014 7:58:24 PM PST by Chode (Stand UP and Be Counted, or line up and be numbered - *DTOM* -vvv- NO Pity for the LAZY - 86-44)
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To: Leaning Right

Above my pay grade too FReeper. I heard about another experiment with two paired electrons. Forgive me my recall isn’t what it used to be but the basics are this, the spin of one electron was altered and the paired electron immediately reflected the change. The communication was far faster than the speed of light and the scientista performing the experiment concluded that everything appears to be interconnected and that when something happens the entire universe is aware of the event. Now that is an impressive idea.


77 posted on 01/22/2014 8:21:33 PM PST by Nuc 1.1 (Nuc 1 Liberals aren't Patriots. Remember 1789!)
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To: a fool in paradise; Slings and Arrows; Glenn; republicangel; Beaker; BADROTOFINGER; etabeta; ...
Ping for the kitty pix.


78 posted on 01/22/2014 8:39:53 PM PST by Slings and Arrows (You can't have Ingsoc without an Emmanuel Goldstein.)
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To: ETL

this description reminds me of manuevring board solutions when doing shipboard operatons - using vectors on speed and position measurement to determine future states of speed and position


79 posted on 01/22/2014 10:19:32 PM PST by reed13k (For evil to triumph it is only necessary for good men to do nothings)
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To: reed13k

Is that Navy talk?


80 posted on 01/23/2014 2:06:34 AM PST by ETL (ALL (most?) of the Obama-commie connections at my FR Home page: http://www.freerepublic.com/~etl/)
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