Skip to comments.Physicists scoop information from Schrodinger's cat box [Quantum Mechanics]
Posted on 01/22/2014 2:53:50 PM PST by ETL
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Schroedinger’s girlfriends would make an interesting study, too.
Well, to be honest, I'm actually a little annoyed with you. You promised that you would be asking stooooopid questions, yet all you've been doing is asking great ones! And if you don't cut it out...
Variation on the cat experiment: instead of a cat, the physicist stuffs one of his grad students into the box. Does the grad student observing his own state collapse the wave function only from his own viewpoint, with his state being a wave function from the viewpoint of the physicist until he opens the box?
And if the grad student, upon being stuffed in the box, has vowed to kill the physicist if he survives the box, is the physicist's existence a wave function until the head of the department opens the lab door to check on him?
One theory is that events that will happen in the future (the observation), have effect on the past; so the act of observation is somehow already bound up with the future observed state. (Not a very coherent explanation, I know.)
A good, and highly readable, book on the weirdosity of quantum events is "In Search of Schrödinger's Cat".
I would just call campus security.
Now, to drive you a bit crazy, I'll add one more thing.
As I said in a previous post, a human does not cause the uncertainty in where an electron really is. The uncertainty is caused by the light-electron interactions.
The human just notices the uncertainty.
So where is the electron? It is exists somewhere within its movement blur. Right? Wrong! It exists everywhere within its movement blur. It exists everywhere it possibly could be.
And the same goes for every object. So let's suppose it's night, and you are inside, far from any window. Where is the moon?
It is everywhere it could possibly be! Could the moon have been struck by a meteor and fallen into the sun? Possibly. So "part" of the moon's "existance" really is in the sun.
Only when you observe the moon does it come into being in one place. All other possiblities become zero. So in this part of quantum mechanics, human observation really does change things!
This was all stated mathematically by Schrodinger. And it's so weird that Einstein refused to believe in any of it. Experiments have since proved that Schrodinger was right and Einstein was wrong.
Another great book by John Gribbin is The Matter Myth which he co-wrote with my favorite science author, Paul Davies.
Schrodinger’s Kittens and the Search for Reality: Solving the Quantum Mysteries - by John Gribbin
All are wonderfully written for the intermediate level reader. These two guys really have a knack for making the complex comprehensible.
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.
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?
You’re welcome. Thanks for pinging your mob over here. :)
“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.”
Once we have measured the system, we know its current state and this stops it from being in one of its other states. 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.
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".
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. 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. An alternative version of the uncertainty principle, more in the spirit of an observer effect, 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."
Please ping me to the Quantum Mechanics / pix of cats in boxes threads!
Fascinating questions. Delightful even. And fun to think about. But sadly, it would take someone well above my pay grade to answer them.
Awww, had a collapse of the wave function?
Thanks for the ping!
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.
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.
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
Is that Navy talk?
Excellent! Amazon is my go-to place for... well, just about everything.
Physicist (courtesy ping) hasn’t posted since last March.
In fact, the mere act of opening the box will determine the state of the
cat, although in this case there were three determinate states the cat
could be in: these being Alive, Dead, and Bloody Furious.
—Terry Pratchett, Lords and Ladies
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