Which-way detector unlocks some mystery of the double-slit experiment

Jan 21, 2011 By Lisa Zyga feature
With a filter over the right slit, electrons are more likely to undergo inelastic scattering and act like a spherical wave. Electrons passing through an uncovered slit are more likely to undergo elastic scattering and act like a cylindrical wave. The two different waves do not have a phase correlation and so, even if an electron passed through both slits, it could not create an interference pattern. Image credit: Frabboni, et al. ©2011 American Institute of Physics.

(PhysOrg.com) -- One of the greatest puzzles of the double-slit experiment – and quantum physics in general – is why electrons seem to act differently when being observed. While electrons traveling through a barrier with two slits create interference patterns when unobserved, these interference patterns disappear when scientists detect which slit each electron travels through. By designing a modified version of the double-slit experiment with a new "which-way" electron detector at one of the slits, a team of scientists from Italy has found a clue as to why electron behavior appears to change when being observed.

As one of the most famous experiments in quantum physics, the double-slit experiment demonstrates how the quantum world is very different from the classical world. When macroscale objects are shot at a barrier with two slits, the objects travel straight through the slits and leave two straight lines on the wall behind the barrier. But when are used instead of macroscale objects, they do not leave two straight lines on the wall but an of many lines. Because the interference pattern remains even when the electrons are shot one at a time, the experiment seems to suggest that each electron somehow travels through both slits at the same time and interferes with itself, like a wave instead of a particle.

The second unusual part of the double-slit experiment is that the electrons stop creating an interference pattern when scientists set up a detector near one of the slits to determine which slit(s) an electron is passing through. Under these circumstances, the electrons simply create two straight lines, the same as classical particles.

Throughout the years, scientists have demonstrated different versions of the two-slit experiment. In the new study, physicists Stefano Frabboni from the University of Modena and Reggio Emilia and the CNR-Institute of Nanoscience in Modena, Italy; Gian Carlo Gazzadi from the CNR-Institute of Nanoscience; and Giulio Pozzi from the University of Bologna have presented another version of the two-slit experiment using a transmission electron microscope.

“Over the last few years, we tried to use our expertise in transmission electron microscopy and focused ion beam specimen preparation to realize some basic experiments related to some of the ‘mysteries’ of quantum mechanics, as pointed out by Feynman in his celebrated lectures and books,” Frabboni told PhysOrg.com.

First, the scientists used focused ion beam milling to make two nanoslits on a barrier. Then they modified one of the slits by covering it with a filter made of several layers of “low atomic number” material to create a which-way detector for the electrons passing through.

Although the electrons (which were shot one by one) could still pass through the filtered slit, the filter caused more of the electrons to undergo inelastic scattering rather than elastic scattering. As the physicists explained, an electron undergoing inelastic scattering is localized at the covered slit, and acts like a spherical wave after passing through the slit. In contrast, an electron passing through the unfiltered slit is more likely to undergo elastic scattering, and act like a cylindrical wave after passing through that slit. The spherical wave and cylindrical wave do not have any phase correlation, and so even if an electron passed through both slits, the two different waves that come out cannot create an interference pattern on the wall behind them.

The physicists also found that the thickness of the filter determined the interference effects: the thicker the filter, the greater the probability for inelastic scattering rather than elastic scattering, and so the fewer the interference effects. They could make the filter thick enough so that the interference effects canceled out almost completely.

“When the electron suffers inelastic scattering, it is localized; this means that its wavefunction collapses and after the measurement act, it propagates roughly as a spherical wave from the region of interaction, with no phase relation at all with other elastically or inelastically scattered electrons,” Frabboni said. “The experimental results show electrons through two slits (so two bright lines in the image when elastic and inelastic scattered electrons are collected) with negligible interference effects in the one-slit Fraunhofer diffraction pattern formed with elastic electrons.”

In a separate study, the physicists covered both slits to see if two spherical waves would create an interference pattern. They found that, in the very faint inelastic intensity, no fringes seem present, whereas interference fringes are recovered, at a very low intensity, when the elastic image is taken.

Overall, the results suggest that the type of scattering an electron undergoes determines the mark it leaves on the back wall, and that a detector at one of the slits can change the type of scattering. The physicists concluded that, while elastically scattered electrons can cause an interference pattern, the inelastically scattered electrons do not contribute to the interference process.

Explore further: Thermoelectric power plants could offer economically competitive renewable energy

More information: Stefano Frabboni, Gian Carlo Gazzadi, and Giulio Pozzi. “Ion and electron beam nanofabrication of the which-way double-slit experiment in a transmission electron microscope.” Applied Physics Letters 97, 263101 (2010). DOI:10.1063/1.3529947

4.3 /5 (52 votes)

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fmfbrestel
5 / 5 (5) Jan 21, 2011
um.. ok.. Can someone please tell me the point of this experiment? It doesn't seem like they really learned anything that wasn't known before the experiment?

If you want to hear a very good explanation of quantum strangeness, you should search the google tech talks for "quantum conspiracy" (the title is meant to be ironic). The speaker does a very good job of making much of the counter-intuitive nature of quantum mechanics seem intuitive.
Skeptic_Heretic
4.9 / 5 (8) Jan 21, 2011
So this experiment isn't being explained properly.

The filter acts in place of a photon detector and forces wave function collapse through expected interaction.

I'm not understanding what the goal of this was. I'm fairly sure that we already knew that inelastic scattering did not provide wave action.
nuge
2.6 / 5 (5) Jan 21, 2011
um.. ok.. Can someone please tell me the point of this experiment? It doesn't seem like they really learned anything that wasn't known before the experiment?

If you want to hear a very good explanation of quantum strangeness, you should search the google tech talks for "quantum conspiracy" (the title is meant to be ironic). The speaker does a very good job of making much of the counter-intuitive nature of quantum mechanics seem intuitive.


I think it was Bohr himself who once said that if you think quantum mechanics makes sense, you haven't really understood it. Something like that, anyway.
fmfbrestel
5 / 5 (2) Jan 21, 2011

I think it was Bohr himself who once said that if you think quantum mechanics makes sense, you haven't really understood it. Something like that, anyway.


Way overused quote. We know much more about quantum interactions now then we did then.

Anyway, the thesis of the presentation i refered to is this: entanglement is mathematically identical to measurement which is why you cant communicate faster then light speed with a quantum setup -- because the entanglement "collapses" (although that term is not really accurate) the interference.
WhiteJim
2.8 / 5 (13) Jan 21, 2011
Electrons slit effect is macro manifestation of the uncertainty principle. Precise location of quantum particle cannot be known but for a degree of uncertainty. Uncertainty relates to distance from center of most probable thus producing a wave-like location to describe the actual particle location which cannot be known for certain. This three dimensional wave or cone of its motion centered on the most probable location which would be the denser. Since the particle through the slits is at a variety of chances with a cone shape representation, the interference pattern is related to the slits location from each other and the size of the cone of probability. On changing one slit sufficiently the probabilities change accordingly to the point that only one slit receives from any single cone eliminating the pattern.
Rather than considering the electron as a point or a wave then consider it to be in the shape of a cone of probability.
I.M.O.
Moebius
1.4 / 5 (14) Jan 21, 2011
Sounds to me like they are putting more meat into the word 'seeming' which should always go in front of the word paradox. A paradox, like infinity, can't exist. A paradox is always an error of assumption or a lack of knowledge, it can't exist, thus all paradoxes only seem to be paradoxes.

This also seems to me to be a misunderstanding in physics. Of course observing something changes it at the molecular level, observing it affects it physically. It's like the difference between passive and active sonar. There is no analogy to passive sonar in the quantum realm, it is all active and it affects what is being observed physically, not magically. This seems to me what this experiment is showing.
antialias_physorg
4.3 / 5 (14) Jan 21, 2011
The point of the experiment, as I see it, is to have a tunable which way detector. We know that if we absolutely nail down the path the electron takes (by a 'hard' which way detector) then interference doesn't happen.

What this experiment shows is that if you use a 'soft' filter (i.e. one that only forces your electron into a certain type of behaviour with a probaility lower than one) then you will only get gradual interference. It also shows which type of filter is more effective at localizing the electrons (i.e. which type takes more information out of the flight path and hence reduces the interference pattern most): those that force elastic or those that force inelastic scattering.

I'd say this is a good step forward.
gshanemiller
1.5 / 5 (4) Jan 21, 2011
What did this experiment have to say about an electron's wave interfering with itself? Nothing, right? So it's still the major question on that table.
gwrede
1.8 / 5 (13) Jan 21, 2011
I think the only thing this experiment shows is, the Italians are as clueless about this as everybody else. If there were any understanding, it would be in textbooks, and they wouldn't do this experiment.

I think the double slit experiment is the easiest one that shows us nobody understands this properly. (And inventing the wave function and its collapse doesnt count as understanding -- that's just observing and inventing math to match it.)
retrosurf
4.7 / 5 (25) Jan 21, 2011
The discussion in this thread has been helpful for my understanding.

The absence of global warming contrarians and creationist propagandists probably contributes to that.

YouAreRight
2.7 / 5 (6) Jan 21, 2011
@qwrede
... that's just observing and inventing math to match it ...


Err, isn't that what physics is all about. Observing somthing then developing an abstract(maybe mathmatical) model to predict future events?
You can never truley say you know somthing to 100% accurracy and therefore understand it absolutely.

That's not to say we aren't extremely accurate though. From memory Feynman's analogy was. When someone asks, how far away is the moon from me; the question arrises do you mean from your neck, or the top of your head. That was from at least 30yrs ago.

I think @antialias_physorg has the right idea about this experiment.
NickFun
1.3 / 5 (16) Jan 21, 2011
Ever since PhyOrg published that story about the two Italians who discovered cold fusion I have been dubious about the stories published here.
fmfbrestel
4.5 / 5 (2) Jan 21, 2011
Ever since PhyOrg published that story about the two Italians who discovered cold fusion I have been dubious about the stories published here.


Someone is new the site. :) get used to it. If you really want to really know about almost anything on here, you are going to have to do some google searches.
rah
1.7 / 5 (11) Jan 21, 2011
Keep moving folks...nothing to see here.
PS3
1 / 5 (6) Jan 22, 2011
was reading on entanglement. doesn't that prove at least one more dimension with how they communicate.
Moebius
2.1 / 5 (18) Jan 22, 2011
I think the only thing this experiment shows is, the Italians are as clueless about this as everybody else. ....


So if it was done by americans you would have said the americans are as clueless as everyone else? I hate all generalizations.
dedereu
1.5 / 5 (8) Jan 22, 2011
This experiment shows that the measurement is not made by the observing human, as proposed by some interpretation of quantum mechanics, but by loosing energy incoherently with the the environnement and loosing the coherence of the wave function, result nearly evident, because you cannot have interferences witout coherent oscillations.
But the mystery of quantum machanics is not better understood, how can a qantum system be in many states in the same time (millions or billions of places at the same times for diffracting particles like photons, electrons and molecules) being both a wave and a particle and collapse at only a single place when loosing energy and coherence, among such a trillions of places over all our universe on a sphere of 10 billions years for a photon emitted by an atom in a galaxy 10 billions years ago !! !!
antialias_physorg
5 / 5 (8) Jan 22, 2011
It's not a wave or a particle. Get this out of your head. Stuff has particle-LIKE beahviour (i.e. behaviour that WE think idealized particles would have) and wave-LIKE behavior (i.e. behavior which WE associate with an ideal model of a wave).

The mystery is why people continue to cling to the notion that there are such things as idealized particles and idealized waves at all.
MZavros
5 / 5 (2) Jan 22, 2011
Uh... am I missing something? Replacing a detector with a filter? I don't see anything new here. Anybody? Bueller?
Noumenon
3.7 / 5 (83) Jan 23, 2011
It's not a wave or a particle. Get this out of your head. Stuff has particle-LIKE beahviour (i.e. behaviour that WE think idealized particles would have) and wave-LIKE behavior (i.e. behavior which WE associate with an ideal model of a wave).

This is correct. There is no reason to suppose that realty should conform to our a-priori notions or epistemological means of ordering experience, on a scale far removed from that which the mind has evolved. Therefore any understand, in the classical intuitive sense, is out of the question from the start. Heisenberg's matrix mechanics is equivalent to Schrodinger's visualizable wave picture, but doesn't imply the false hope.
Noumenon
3.6 / 5 (84) Jan 23, 2011
It's not a wave or a particle. Get this out of your head. Stuff has particle-LIKE beahviour (i.e. behaviour that WE think idealized particles would have) and wave-LIKE behavior (i.e. behavior which WE associate with an ideal model of a wave).

This is correct. There is no reason to suppose that realty should conform to our a-priori notions or epistemological means of ordering experience, on a scale far removed from that which the mind has evolved. Therefore any understand, in the classical intuitive sense, is out of the question from the start. Heisenberg's matrix mechanics is equivalent to Schrodinger's visualizable wave picture, but doesn't imply false hope.

P.S.,.. AGW is non-sense.
Ethelred
1.8 / 5 (6) Jan 24, 2011
What did this experiment have to say about an electron's wave interfering with itself? Nothing, right?
No, not right at all.
Although the electrons (which were shot one by one)
Read more carefully. This is only the umpteenth one by one test. ALL of the one electron or on photon at a time tests have had the test energy packet interfering with itself unless there a detector of some kind.

Ethelred
Ethelred
2.1 / 5 (7) Jan 24, 2011
I think @antialias_physorg has the right idea about this experiment.
I think it shows more than that.

It shows the idea that a sentient observer is needed is nonsense. There was no actual detector. Just a quantum filter that effected the wave's path probabilistically. The greater the filtering the less the interference.

What intrigues me is something that the experiment might not have the sensitivity to show. Does a SINGLE electron show a BOTH some interference and some direct path effects? In the terms of the experiment and quantum mechanics there should be BOTH spherical and columnar waves from the filtered side with EACH electron tested.

Ethelred
vikashbajaj
3 / 5 (1) Jan 24, 2011
Double slit experiment is basically used to study the interference of light, where a screen is placed at a distance (approx. 0.5m-1m) and we get patterns on the screen. The patterns are termed as fringes. The bright fringe(a bright line) tells that contructive interference took place at that line and a dark fringe would demonstrate the destructive interference.
this experiment is also used for quantum phy, in place of a normal screen, a different screen is used to detetect the electrons.
In this experiment, when a slit is a line, cylindrical wavefronts are formed and in the case where filter has been used, the eectrons undergo inelastic collision and the eletron which go through the filter now has a point shaped slit which forms spherical wavefront.
i hope m correct abut what m saying, if not plz correct me.

Vikash
neiorah
2 / 5 (3) Jan 24, 2011
I hate that dullards advertise on this site in the areas meant for serious comments on the subject posed
Noumenon
3.5 / 5 (84) Jan 24, 2011
It shows the idea that a sentient observer is needed is nonsense. There was no actual detector. Just a quantum filter that effected the wave's path probabilistically. The greater the filtering the less the interference.
Wrong, there IS a detector made by a sentient being. There doesn't appear to be anything fundamentally new here. The electron 'feeling out' possible paths is still being affected by what is in effect an observation, because the experimenters know the effect of the filter and incorporate this knowledge into the final analysis.
Ethelred
3.6 / 5 (9) Jan 24, 2011
Wrong, there IS a detector made by a sentient being.
Wrong. There is NO detector for the electron's path. And it doesn't matter if the sensor was made by a sentient being. There was NO OBSERVER. Just a dumb sensor.
There doesn't appear to be anything fundamentally new here.
Actually there is. A quantum electron filter that should both pass and not pass the electron at the same time. Can't help if the sensor can't make use of that.
The electron 'feeling out' possible paths is still being affected by what is in effect an observation,
Non sentient. Feeling out is a poor choice of words unless you insist on forcing sentience where there isn't any.
because the experimenters know the effect of the filter and incorporate this knowledge into the final analysis.
That is like the Creationists demanding lab tests and then claiming they don't mean anything because a human made the lab.

Ethelred
Noumenon
3.5 / 5 (84) Jan 24, 2011
Wrong, there IS a detector made by a sentient being.

Wrong. There is NO detector for the electron's path. And it doesn't matter if the sensor was made by a sentient being. There was NO OBSERVER. Just a dumb sensor.
The experimenters know the thickness of the filter therefor in effect it is an observation. Your definition of 'observation' is far too narrow here. Any equipment designed and used to interface with a qm system coupled with an attempt at rationalizing the results, IS an observation! 
Noumenon
3.6 / 5 (83) Jan 24, 2011

The electron 'feeling out' possible paths is still being affected by what is in effect an observation,

Non sentient. Feeling out is a poor choice of words unless you insist on forcing sentience where there isn't any.
The phrase 'feeling out' describes what a qm entity 'appears' to be doing,... used by Feynmen, Penrose, and others. Obviously this experiment shows that the electron somehow 'considers' both slits before 'deciding' upon which one or both it will go through. These terms of course are not meant as literal.
Noumenon
3.6 / 5 (84) Jan 24, 2011
because the experimenters know the effect of the filter and incorporate this knowledge into the final analysis.

That is like the Creationists demanding lab tests and then claiming they don't mean anything because a human made the lab.
I'm not claiming it doesn't mean anything, and am not religious. The salient point here is that a conceptualization of Reality does not leave it in it's original form, it becomes altered. Reality as it is in itself is not in the same form as it is conceptualized. This is why qm can not be intuitively rationalized. This is why the 2-slit experiment is so bizarre. The above filter does not fix this problem.
Noumenon
3.7 / 5 (82) Jan 24, 2011
An analogy wrt 'feeling out' paths is the principal of least action. How does a system 'know' to take the path of the smallest Lagrangian? Of course it doesn't know anything, but WE conceptualize it AS IF it must 'feel out' ahead of time, because that's how WE would determine it, given our make up.
Ethelred
2.6 / 5 (5) Jan 24, 2011
Your definition of 'observation' is far too narrow here.
Rubbish. That is just your Kant based silliness.
IS an observation!
The filter was the observer. No human involved.
The phrase 'feeling out' describes what a qm entity 'appears' to be doin
There is no entity.
Obviously this experiment shows that the electron somehow 'considers' both slits before 'deciding' upon which one or both it will go through.
There is no decision.
These terms of course are not meant as literal.
Then don't use them. The fact is the equations are wave equations. Waves are effected by the paths. Change the path and you change the wave. In this case the path is probabilistic due the quantum nature of the filter.
The salient point here is that a conceptualization of Reality
There is no conceptualization involved in the path the electron takes.

More
Ethelred
2 / 5 (4) Jan 24, 2011
Reality as it is in itself is not in the same form as it is conceptualized.
There is no experimental reason to assume there isn't an objective reality. Just that Kant crap you push.
This is why qm can not be intuitively rationalized.
Speak for yourself.
This is why the 2-slit experiment is so bizarre.
Not to me.
The above filter does not fix this problem.
There is no problem except for a poor choice models in YOUR head. Most likely due to Kant AND that silliness called the Copenhagen Model.
a system 'know' to take the path
It doesn't. It takes them all.
, but WE conceptualize it AS IF it must 'feel out'
You do that. I don't.
how WE would determine it
You, not me.

Ethelred
Noumenon
3.6 / 5 (84) Jan 24, 2011
You're responding to half-sentences now?, what's next syllables?
This is why the 2-slit experiment is so bizarre.

Not to me.

The above filter does not fix this problem.

There is no problem except for a poor choice models in YOUR head. Most likely due to Kant AND that silliness called the Copenhagen Model.

Right, to paraphrase a famous physicist, 'if you're not bewildered and astonished by qm, you don't understand it'. You think that a mind evolved to function on the macro scale can rationally apply it's a-priori intuition to all reality?
a system 'know' to take the path

It doesn't. It takes them all.
The Copenhagen, epistemological, Kant, interpretation is several orders of magnitude more rational than "many-worlds".
AJMeyer
2 / 5 (5) Jan 24, 2011

"With a filter over the right slit, electrons are more likely to undergo inelastic scattering and act like a spherical wave. Electrons passing through an uncovered slit are more likely to undergo elastic scattering and act like a cylindrical wave. The two different waves do not have a phase correlation and so, even if an electron passed through both slits, it could not create an interference pattern."

This is interesting, because with coherent light, a slit producing a cylindrical wave and a tiny hole producing a spherical wave will produce an interference pattern.

Do the experiment yourselves with a small laser pointer.

So why do electrons behave differently?

A.J.
Noumenon
3.7 / 5 (81) Jan 24, 2011
@Meyer.
There is no tiny hole, both slits are rectangular. If the electron interacts with the filter, a measurement is in effect performed, which causes the electrons wavefuction to collapse (state reduction), to a observable value. From there the wavefuncion evolution starts over, but since it's already at the slit the wave is spherical (not conformed to the slit geometry).

The case you mention does not apply because they are only firing one electron (or photon) at a time. It won't interfere with itself for the above reasons.
Ethelred
1.7 / 5 (6) Jan 25, 2011
You're responding to half-sentences now?, what's next syllables?
Little things for little minds. You and MS Word Grammar botch seem to be equivalent on this.
'if you're not bewildered and astonished by qm, you don't understand it'.
To reiterate what someone else already pointed on this thread that is OLD and out of date. Someone said the same thing about evolution. That too is obsolete.
You think that a mind evolved to function on the macro scale can rationally apply it's a-priori intuition to all reality?
Who the hell is going on intuition? YOU maybe. Not me. I am using reason.
The Copenhagen, epistemological, Kant, interpretation is several orders of magnitude more rational than "many-worlds".
Utter nonsense. FIRST Kant didn't know anything about this. SECOND the Copenhagen Model and the Many-Worlds model are mathematically the same. So you are full of it. THIRD the Copenhagen Model is what is confusing you and others.

More
Ethelred
2.6 / 5 (5) Jan 25, 2011
The Many-Worlds Model, at least as expanded by me,EXPLAINS things. Like why there is something instead of nothing. Which gives it an advantage over the Copenhagen silliness about collapsing waves being effected by the alleged sentience of a set atoms and not being effected by a non-sentient set. Pure silliness. Right up there with the Geocentric thinking.

AND FOURTH I was going on the Wave model the other day. Not the Many Worlds but both the get the same results. I use them both at will.

As Dr. Feynman said about his brother and algebra 'the idea is to get the answer'.

Yes the Many-Worlds Model disturbs people. So did the Copenhagen Model. People just got used to it even though it didn't explain anything the math didn't. The Many Worlds Model DOES.

If you have two models of the Universe and both produce the same numbers with the same equations then the one that tells you MORE is the better model.

Try getting out of that Norwegian rut.

Ethelred
Noumenon
3.7 / 5 (81) Jan 25, 2011
First, we are speaking about interpretations here, and MWI is an interpretation.

Second, the role of science is no longer to "explain" things. THAT is out dated. It is to formulate a model that will allow for predictions. That is all. This is the point my associating Kant with Bohr ideas on the interpretations, it is a rational reason why we can't have an intuitive (classical) understanding of qm.

To deny wavefunction collapse is to associate a independent reality to it as some existent entity, that maintains a temporal existence even after a state reduction to an observable state.,...
Noumenon
3.7 / 5 (80) Jan 25, 2011
,... There are several problems with this. One is that it is presumed that the wavefunction is a physical entity even though it is not possible to observe it in such a form, but only in a collapsed state (eigenvalue). Like wise the splitting into multiple universes at each interaction is unobservable, so again as such there is no scientific validity in proposing the existence multi-universes, unless it is merely regarded as a mathematical scheme.
Skeptic_Heretic
5 / 5 (2) Jan 25, 2011
Second, the role of science is no longer to "explain" things. THAT is out dated. It is to formulate a model that will allow for predictions.
In order to predict, you must be able to post hoc explain as well. The two skill sets are perfectly congruent.
This is the point my associating Kant with Bohr ideas on the interpretations, it is a rational reason why we can't have an intuitive (classical) understanding of qm.
I think it is more a matter of social framework and background. Grow up reading the I Ching and you'll have a more intuitive, but not perfectly so, understanding of QM than you would reading the more linear social commentaries and foundational documents, like the KJV, Torah, etc.
To deny wavefunction collapse is to associate a independent reality to it as some existent entity, that maintains a temporal existence even after a state reduction to an observable state.,...

He's not denying it. He's denying the CI stance on it.
Noumenon
3.7 / 5 (82) Jan 25, 2011
Which gives it an advantage over the Copenhagen silliness about collapsing waves being effected by the alleged sentience of a set atoms and not being effected by a non-sentient set. Pure silliness.
It appears silly because you fail to grasp it.

A qm system is a singular wavefucntion and may include whatever set of atoms you like as a system,.. the point is it is NOT observable until it is forced to take on a known form,.. I.e. a measurement designed and interpreted by a mind. There is no mystical magic here, it is purely logical.
Noumenon
3.7 / 5 (80) Jan 25, 2011
He's not denying it. He's denying the CI stance on it.
What? I thought that was the entire premise of MWI, that the wavefunction never actually collapses, that all possibilities exist in other universes, or some such cartoon thumb sucking? Correct?
Skeptic_Heretic
5 / 5 (2) Jan 25, 2011
He's not denying it. He's denying the CI stance on it.
What? I thought that was the entire premise of MWI, that the wavefunction never actually collapses, that all possibilities exist in other universes, or some such cartoon thumb sucking? Correct?

No. The MWI states that at wave form collapse all possibilities occur, resulting in the split, this includes a potential for the wave form to not collapse, so technically it never does, but it does, in every possible configuration as well.
Basically the MWI removes the superposition and satisfies it with the equivalent of brute force.

I see the CI as being artificially limited based on presupposition.
Noumenon
3.7 / 5 (79) Jan 25, 2011
Little things for little minds. You and MS Word Grammar botch seem to be equivalent on this.
What does this mean? I post on my iPhone, so perhaps the auto-word correct gave the wrong word?
Noumenon
3.7 / 5 (81) Jan 25, 2011
Yes, SH, that's what I understood, that "all possibilities occur" in MWI. Unobservable and speculative. Where as CI would say that forcing the "thing" modeled by the wavefuncion to take up a OBSERVABLE state, disturbs the "thing" in such a way that the model must start over with the given observed info as it's new state. It's the interfacing of what is observable with reality. Observable of course by definition involves a mind.
Skeptic_Heretic
5 / 5 (2) Jan 25, 2011
Yes, SH, that's what I understood, that "all possibilities occur" in MWI. Unobservable and speculative.
How is it unobservable? And as for speculative, it is certainly less speculative than saying that an object has all possibilities until it is observed. "If a tree falls in the woods, with no one to hear it, does it make a sound?" Yes. In all cases thus far, it does.
It's the interfacing of what is observable with reality. Observable of course by definition involves a mind.
Meaning that all of reality doesn't exist prior to the existence of a sentience, and that is nonsense. You create the need for a presupposition of sentinece in reality which can't be unless sentience is a supernatural element. Otherwise there would be no reality to give rise to sentience. And the supernatural is absolutely unobservable.
Noumenon
3.7 / 5 (81) Jan 25, 2011
@SH, you completely misunderstand what I'm saying. I never entered into idealism, i.e. that a independent reality doesn't exist except as conceived in thought. Look up my screen name for example.
is certainly less speculative than saying that an object has all possibilities until it is observed
Again I never said that an object has all possibilities. An object exists in Noumenal reality until it is conceptualized by being observed, upon which it is conformed by the intellectual faculties necessary for a thing to be known by a mind. I'll have to try to explain better later.

I can see how this seems like word salad, but Kant is the epitome of reason.
Ethelred
2.6 / 5 (5) Jan 25, 2011
First, we are speaking about interpretations here, and MWI is an interpretation.
Model. So is Copenhagen.
Second, the role of science is no longer to "explain" things. THAT is out
Nonsense. Literally.
It is to formulate a model that will allow for predictions.
Which is explaining things.
This is the point my associating Kant with Bohr ideas on the interpretations, it is a rational reason why we can't have an intuitive (classical) understanding of qm.
Since I have a rational reason that is false. Classical and intuitive are different things and NEITHER is required for rationality.
To deny wavefunction collapse is to associate a independent reality to it
Damn straight. Most scientists, especially those that actually DO things believe in an objective reality. Only people that have polluted their brains with out of date philosophy think otherwise.
some existent entity,
Entity doesn't enter into it.

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Ethelred
2.3 / 5 (3) Jan 25, 2011
that maintains a temporal existence even after a state reduction to an observable state
That is word wooze based on the model I don't use. There is no state reduction in my thinking. None is needed.
One is that it is presumed that the wavefunction is a physical entity even though it is not possible to observe it in such a form,
We detect the results and the equations are wave functions. It is silly to assume the wave functions don't fit something that is real. To assume that is to assume you are wasting your time even getting up in the morning.
but only in a collapsed state (eigenvalue)
There is no collapse.
Like wise the splitting into multiple universes at each interaction is unobservable
The math works. So I have reason to assume it is real. The Copenhagen Silliness IGNORES the math.
there is no scientific validity in proposing the existence multi-universes
It is mathematically valid. Science is based on math. Read between the lines.

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Ethelred
2 / 5 (4) Jan 25, 2011
unless it is merely regarded as a mathematical scheme
Again that is silly since when we assume the math matches reality we get somewhere. When we pretend that it doesn't we get the Copenhagen non-model.

SH
He's not denying it
Actually I am denying a collapse. The math is wave based and the Many Worlds has no collapse either. In the MW model ALL possibilities are real and the math fits that.
never actually collapses
Yep.
some such cartoon thumb sucking?
No. The cartoon stuff is a collapse. See Maroon Cartoons.

SH
all possibilities occur
Which is not collapsing as the concept behind a collapse is that only ONE state is real.
What does this mean?
It means you and the Grammar Check in MS Word agree. This is not a good sign as competent writers think MS's Grammar Check is deranged. I sell the thing and few people that can write like the Grammar Check.

Definition of being able to write. It flows and you don't have to open a vein.

Ethelred
Skeptic_Heretic
not rated yet Jan 25, 2011
Definition of being able to write. It flows and you don't have to open a vein.
But if you're doing said writing with the interface of a smart phone, you may want to open a few veins.
SH, you completely misunderstand what I'm saying. I never entered into idealism, i.e. that a independent reality doesn't exist except as conceived in thought. Look up my screen name for example.
Irrelevant, pushing for the CI engages this line of reasoning.
I can see how this seems like word salad, but Kant is the epitome of reason.
And this is why Kant is not the epitome of reason.
Noumenon
3.7 / 5 (79) Jan 25, 2011
It means you and the Grammar Check in MS Word agree. This is not a good sign as competent writers think MS's Grammar Check is deranged. I sell the thing and few people that can write like the Grammar Check.

Definition of being able to write. It flows and you don't have to open a vein.

I still fail to get your point here. Could you give an example? I write on my iPhone, posting on an forum, and have limited time to convey a difficult philosophy to people who believe in alternate universes, and must wirte in a condensed fashion. Maybe I understand you now.

I'll have to respond later to the several misunderstandings you put on display, above, but in short, I never denied an objective reality, and 'intuitive understanding' and 'classical' should be familiar to anyone who knows modern physics history.

Anyway are you not the one who said 'the only difference between me and the cranks was that I was a better writer'?
frajo
3.7 / 5 (3) Jan 25, 2011
MWI is an interpretation.
Model. So is Copenhagen.
Models are, unlike interpretations, falsifiable.
Second, the role of science is no longer to "explain" things. THAT is out
Nonsense. Literally.
It is to formulate a model that will allow for predictions.
Which is explaining things.
Only if model==reality is assumed.
Most scientists, especially those that actually DO things believe in an objective reality.
That's not equivalent to the assumption model==reality.
Only people that have polluted their brains with out of date philosophy think otherwise.
This is a subjective metaphysical position with an ad-hominem flair. To be "out of date" is not a rational argument.
Noumenon
3.7 / 5 (79) Jan 25, 2011
,.. not to mention, he is proclaiming Kant out of date, yet does not demonstrate he understands it, nor it's application I'm making use of.
Skeptic_Heretic
4 / 5 (1) Jan 25, 2011
,.. not to mention, he is proclaiming Kant out of date, yet does not demonstrate he understands it, nor it's application I'm making use of.

You don't need to understand the ins and outs of hunting with spears to know it is an outdated practice when it comes to hunting deer.

Such is the application of Kant to science.
Noumenon
3.7 / 5 (80) Jan 25, 2011
Well, if you don't know what a spear is,....
Skeptic_Heretic
5 / 5 (2) Jan 25, 2011
Well, if you don't know what a spear is,....

You still know how to hunt. And this back and forth shows the problem. Kant is subtly prone to the same fault of Plato. The requirement to redress shortcommings in explanation sans metaphysics, which are unreasonable.

It always requires a predefining mechanism of unobservation, but that's the problem. Nothing that exists is unobservable. We may have a limited refernce frame, but our myopic existence doesn't have a defining metric upon reality.
Noumenon
3.7 / 5 (81) Jan 25, 2011
You still know how to hunt
Yes, but if a guy is beating the deer over the head with the spear rather than shooting it, he really shouldn't be making determinations of it's value. I think Ethelred understands more than he let's on, he just likes to represent me as a metaphysic crank, so his alternate universes seems reasonable by comparison.
Skeptic_Heretic
5 / 5 (2) Jan 25, 2011
Yes, but if a guy is beating the deer over the head with the spear rather than shooting it, he really shouldn't be making determinations of it's value. I think Ethelred understands more than he let's on, he just likes to represent me as a metaphysic crank, so his alternate universes seems reasonable by comparison
Well seeing as you're sort of "polishing Kant's apple" so to speak, I'd tend to agree with him.
Noumenon
3.7 / 5 (79) Jan 25, 2011
,..
Noumenon
3.7 / 5 (81) Jan 25, 2011
It always requires a predefining mechanism of unobservation, but that's the problem. Nothing that exists is unobservable. We may have a limited refernce frame, but our myopic existence doesn't have a defining metric upon reality.

I can’t agree. The ‘defining metric’ are the conditions for *understanding to be possible in the first place,.. that a-priori intellectual intuitions determine the form of the experience and so understanding, i.e time, space, and causality are such conditions the mind conforms reality to. There is no time entity out there, this is added by the mind, …it is a condition for understanding to be possible.
 
Reality as it is in itself, unconceptualized, must differ from phenomenal reality because phenomenal reality contains the subjective component, i.e. conditions required for knowledge to be possible.
 
*I mean here intuitive understanding (i.e.
Noumenon
3.7 / 5 (81) Jan 25, 2011
Of course there is an existing objective reality apart from a mind,.. this is what I call Noumenal reality. It is merely that our classical understanding, phenomenal reality, is conditioned by the processes of the mind. Qm is not intuitively rational because Noumenal reality does not care for such intuitions of the mind.
Noumenon
3.7 / 5 (77) Jan 25, 2011
Kant is subtly prone to the same fault of Plato. The requirement to redress shortcommings in explanation sans metaphysics, which are unreasonable
Actually Kant's purpose in his Critique was to deliniate metaphysics from knowledge,.. i.e. metaphysics cannot be a source of knowledge!
rah
1 / 5 (4) Jan 25, 2011
I kant understand what y'all are talking about.
Skeptic_Heretic
3 / 5 (2) Jan 26, 2011
I can't agree. The 'defining metric' are the conditions for *understanding to be possible in the first place... that a-priori intellectual intuitions determine the form of the experience and so understanding, i.e time, space, and causality are such conditions the mind conforms reality to. There is no time entity out there, this is added by the mind, it is a condition for understanding to be possible.
And this is demonstrably wrong.

You keep pumping Kant and stating he seperated the physical from the metaphysical. If that was the case, Kant wouldn't have fallen so hard on his face when he tried to create an objective moral framework.
Noumenon
3.7 / 5 (80) Jan 26, 2011
How is that 'demonstrably wrong'? I don't are about his moral framework. I only mention his core epistemology to explain why the Bohr point of view makes sense,.. that physics shouldn't be expected to "explain" things so that it is intuitively satisfying, i.e. it is pointless to propose MWI or that wf-collapse is a 'problem'.

Kant was not correct about several things. All that I'm taking from him is that there cannot be a one-to-one correspondence between reality as it-is-in-itself, and reality as Conceptualzed. The latter is necessarily limited by a-priori faculties of the mind. These intuitions are necessary for ordering experience given the way the mind functions, but results in conceptual artifacts that are not discoverable in themselves apart from there application.
Noumenon
3.7 / 5 (80) Jan 26, 2011
As I said Kant's entire purpose was to determine what can be a source of knowledge. Philosophy requires precise definitions, so there is a difference between knowledge and understanding >1900. For exampe, QM is able to make predictions despite being intuitively inconsistent but IS a form of knowledge. Kant could not have anticipated this and was wrong about it, however, he was correct that such knowledge is not intuitively comprehensible. Feynman is still correct in saying 'no one understands [QED]', despite it's great accuracy. The MWI adds a metaphysical problem in order to take away a supposed problem. As I stated above, if it's just a mathematical means of removing the 'kink' then ok, but that is not explaining anything comprehensible.
Noumenon
3.7 / 5 (80) Jan 26, 2011
The way I view Bohr's point is that 'this is just the way we can get results', 'no need to expect anything further', 'no need to expect intuitive satisfaction', 'there are no more variables to apply'. Shouldn't this attitude be regarded as anti-interpretation or lack of one? After all, accordingly the collapse is not viewed as a problem in itself.
Skeptic_Heretic
not rated yet Jan 26, 2011
that physics shouldn't be expected to "explain" things so that it is intuitively satisfying

and...
The way I view Bohr's point is that 'this is just the way we can get results', 'no need to expect anything further'

Which would be intuitively satisfying. It's a lot easier to say "if we can't see it, it's not real" as opposed to casual reproduction being the norm.

Bohr found CI intuitively satisfying. You're defeating your own arguments here.
Noumenon
3.7 / 5 (79) Jan 26, 2011
What are you talking about!?!?!! The CI was anything but 'intuitively satisfying',... in fact this is why Schrodiner, Einstein, and many others opposed it! The exact opposite is the case.
Noumenon
3.7 / 5 (79) Jan 26, 2011

...I mean by a-priori Intuitions not common usage, but those elements of thought necessary for ordering experience,... space, time, causality,.. which cannot be used to rationalize qm, which is why the gulf between 'classical' physics and qm. Einstein still expected some underlying classical understanding but this subsequently was shown to not exist.
Skeptic_Heretic
5 / 5 (1) Jan 27, 2011
What are you talking about!?!?!! The CI was anything but 'intuitively satisfying',... in fact this is why Schrodiner, Einstein, and many others opposed it! The exact opposite is the case.
The CI is intuitively satisfying from all relevant aspects (read:mathematical). The MWI is brutally painful to rationalize, however that doesn't make it incorrect.

I'm not sure why you're even trying to argue this. Noumenal reality is metaphysics within Kant's framework. It's magic sky fairy crap that was relevant considering Kant was raised in an age when everyone believed in a magic sky fairy. Kant is not the pinnacle of reason and rationale.

That title belongs with Diogenes.
Noumenon
3.7 / 5 (79) Jan 27, 2011
I'm not sure why you're even trying to argue this. Noumenal reality is metaphysics within Kant's framework. It's magic sky fairy crap that was relevant considering Kant was raised in an age when everyone believed in a magic sky fairy. Kant is not the pinnacle of reason and rationale.


Kant is the most influential philosopher of modern times. The existence of Noumenal reality is just logic if you believe in objective reality as it is apart from being conceptualized.

And again CI is NOT intuitively satisfying,.. THAT's WHY IT WAS CONTROVERSIAL.
Noumenon
3.7 / 5 (79) Jan 27, 2011
,..i.e. the state reduction breaks the deterministic Schrodinger equation.
Skeptic_Heretic
not rated yet Jan 27, 2011
Kant is the most influential philosopher of modern times.
He WAS influential, but never the most influential by most descriptions. Kant effectively finalized the work begun by Luther.
The existence of Noumenal reality is just logic if you believe in objective reality as it is apart from being conceptualized.
No, noumenal reality is allegedly an objective characterization of reality, however Kant argues that there is no objective reality, or that it can't be known because we're sentient, sans sentience we would be unable to grasp it, therefore Kant believes in nonsense. He was an unduly elevated Ayn Rand, and Rand is heralded as the worst philosopher ever (other than Derrida that is).
Noumenon
3.7 / 5 (80) Jan 27, 2011
No, noumenal reality is allegedly an objective characterization of reality, however Kant argues that there is no objective reality, or that it can't be known because we're sentient, sans sentience we would be unable to grasp it, therefore Kant believes in nonsense.


Kant never said "there is no objective reality". He believed in objective reality. Later philosophers took his ideas into idealism, which he rejected.

Noumeal reality cannot be known by definition. Phenomenal reality is REAL but contains a subjective component or "colouring" again by definition,... since phenomenal reality is reality as known by a mind.
Noumenon
3.7 / 5 (79) Jan 27, 2011
Rand is heralded as the worst philosopher ever

I fail to see what Rand has to do with this discussion,... but yes, Rand is a "right-winger", laissez-faire capitalist, anti-big government, anti-union, political philosopher. So, ya she is not going to be liked by the opposition. Personally I don't know much about her Objectivism, but I have a feeling that is not the reason she is "heralded as the worst philosopher ever", if indeed that is even the truth.
Skeptic_Heretic
not rated yet Jan 27, 2011
Kant never said "there is no objective reality". He believed in objective reality.
He believed in an objective reality that cannot be observed due to the bias of the subjective self.

He later insinuated that anything unobservable by the subjective self by definition doesn't exist.

Creating this conflict he developed the framework of noumenal existence, in which it exists, objectively, but cannot be measured. Which he previously stated "could not exist". It is the most masterfully crafted and most well obfuscated form of circular claptrap that created Kant's rationality framework, and subsequently sunk his "objective basis of morality". Kant's argument was wholly against empiricism, and he argued it with such vigor that he violated his own argument.

I think most people read only a few arguments by Kant, as reading his entire compendium of works would "drive one mad" according to his contemporaries and many modern philosophers.
Noumenon
3.7 / 5 (79) Jan 27, 2011
He later insinuated that anything unobservable by the subjective self by definition doesn't exist.

Factually incorrect. He was NOT an idealist.

He believed in an objective reality that cannot be observed due to the bias of the subjective self.

Again, factually incorrect. He made the distinction between Noumenal reality and phenomenal reality in order to analyze epistemology,. i.e. our knowledge of reality differs from Reality as it is in itself, due to the act of conceptualization,.. due to a-priori conditions for understanding to be possible, given the nature of mind.

I think most people read only a few arguments by Kant, as reading his entire compendium of works would "drive one mad" according to his contemporaries and many modern philosophers.


I have read Copleston's entire history twice, several volumes multiple times, as well as "The Critique of Pure Reason" itself twice. Your characterization of Kant shows me that the above lines pertain to you precisely
Noumenon
3.7 / 5 (80) Jan 27, 2011
You create the need for a presupposition of sentience in reality which can't be unless sentience is a supernatural element.


In the MWI it is required that a experimenter have a consistent awareness-state that forces the impression that there is one 'universe' in which the state reduction takes place. This is according to Everett himself.
Skeptic_Heretic
not rated yet Jan 28, 2011
1000 characters is utterly insufficient for this conversation. I'll PM you my email address.
Skultch
not rated yet Jan 28, 2011
1000 characters is utterly insufficient for this conversation. I'll PM you my email address.


If you guys get anywhere interesting and conclusive, copy/paste me a PM, would ya? :)
Noumenon
3.7 / 5 (79) Jan 28, 2011
Lol, we'll get this solved, damn it!
donjoe0
1.6 / 5 (9) Jan 31, 2011
I'll just drop in on your little kantian squabble to note that nuge doesn't know what he's talking about and Moebius got everything right with his first intervention. Also, Ethelred makes more sense than Noumenon. :)

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