Jump to content

The Observer Effect


Luc Turpin

Recommended Posts

12 hours ago, studiot said:

 

Put simply The Correspondence Principle basically says that whenever a physical theory is displaced by new theory, the new theory must 'correspond' to the old theory. That is it must match the old theory in those realms of physics that have been tested (by experiment).

Variations/ corollaries of this are RTFM (read the frigging manual) and the so called Domain of Application that every lecturer says at the outset of a series of elctures and everyone promptly forgets about.

So what does this mean for the double slit ?

Well what has been tested ie what actually happens?

That is what do we actually observe and what does it depend on ?

What was the old theory and where does meet and where does it fail the observations ?

And what is the new theory  - obviously in this case the quantum theory - and how does it meet both the conditions the old theory satisfies and those it fails ?

 

Well I contend that too many modern explanations actually degrade the old theory in order to make it look bad.
And of course you have to ask which old theory ?

A wave theory ?

Well there were several levels of wave theory and elementary texts match the simple wave theory of Huygens and Fresnel against quantum statistics.

In fact there are several levels of wave theory, each more exact but more difficult

The first theories due to Grimaldi and Marcus we not of wave interference but wave diffraction.
Grimaldi actually coined the word diffraction.

Undergraduate level Physics today makes a distinction between diffraction and interference.

More advanced work does not. Instead the fully rigorous vector wave theory is based on Maxwell's equations and the boundary conditions associated with the obstacle (in this case the double slit). The boundary conditions are used to calculate a field scattered by the obstacle. The origins of this scattered field lie in currents induced in the obstacle by the incident field. The scattered field is vectorially combined with (allowed to interfere with) the incident field to produce the resultant diffracted field.

This is a very difficult approach, the simplest solutions being the Kirchoff -Sommerfield Integrals.

The normal undergraduate approximation theory is a scalar theory where the Huygens-Fresnel wavelets interfere to produce a new wavefront.

Even this is difficult and produces the Huygens-Fresnel Integral.

An alternative modern treatment involves solving the Helmholtz Equation to find the Gaussian Wave . This can be carried into laser territory.

The problem is that all these methods introduce their own difficulties, for example the backward wave in the Huygens method, which is simply ignored as it is not observed.

 

Bit it was necessary to move on from Grimaldis original (though a nobelworthy effort in 1665) to the nearly accurate version introuced by Young in 1801

 

The intensities and widths of Grimaldis laight and dark zones dod not correspond to observation, in particular the central one was too big.

twoslit1.thumb.jpg.3a5469eadbea4e26bb30c3a71d3ce3a2.jpg

 

 

Thank you for being my teacher; don’t know why you are doing it, but I appreciate it immensely (and learning a lot):

What I got from the text:

  • An old theory is replaced when it fails to explain new observations (experiment results).
  • ¬∑The new theory must explain observations covered by the old theory and attempt to explain new observations not covered by the old theory.
  • There are several levels of wave theories with each one adding more precision, but also difficulty (as in problems??)

Am I missing any important point?

Is there an underlining message that I am not getting? I feel compelled to think that the scientific process is a "perpetual forward moving work in progress". And, depending on your answer to the difficulty-problem question, may also be moving sideways at times to contend with difficulty. What I am getting also is that an answer to a question often times brings up another question, and so on.

 

1 hour ago, studiot said:

 

 

In other words when there is an interaction does a new wave function appear which now includes the 'observer' in the quantum system ?

 

And the answer to this question, if it was you to answer it would be no? right? 

1 hour ago, studiot said:

 

But I keep saying, and I hope you can now begin to see, that the double slit experiment is difficult and complicated for an good intructory explanation of QM.

Point well taken!

13 hours ago, Luc Turpin said:

No one wishing to take this one on?

Link to comment
Share on other sites

14 minutes ago, Genady said:

Why would I read a Scientific American Blog?

Becasue it's by Deepak Chopras's mates ?

 

I'm sorry Luc, that blog reminds me of the early days of the science of Geology.

Lots of discoveries were made by people whose motivation was to prove the glory of God.

 

Link to comment
Share on other sites

So, Scientific American is not a valid source of info; din't know; found them relevant at times!

And din't know as well that they were buddies of Deepak!

So, all that is in the blog is invalid?

I am surprised!

Will be more careful next time!

Apologies to both Genady and studiot for my naivety

Need to ponder what just happened here!

I often times read things while holding my nose, because I need to know what the other side is thinking.

Like in war or politic, I want to hear from both sides, even if one appears to be out of touch with reality.

 

Link to comment
Share on other sites

13 hours ago, joigus said:

We can't "measure the wave." We can use the postulated wave to predict the measurements. The measurements are those dots on a screen.

In fact, there is a theoretical principle, called "gauge invariance" --of which we're pretty certain-- that says there's a big chunck of this wave we cannot know in any way. Some people say it's junk, or a redundancy, etc.

Thanks for mentioning gauge invariance. Again I agree we can't measure the wave. I'm not going to pretend to know all that much in this subject, but attributing that aforementioned big chunk of the wave disappearing to a "collapse" just feels to me like a case of the tail wagging the dog; The "collapsing" to me is just a description of what's seen (because that's the only thing that could be seen) instead of something "being collapsed."

Link to comment
Share on other sites

42 minutes ago, AIkonoklazt said:

Again I agree we can't measure the wave.

Again? Sorry, you said we can a few times.

34 minutes ago, AIkonoklazt said:

but attributing that aforementioned big chunk of the wave disappearing to a "collapse" just feels to me like a case of the tail wagging the dog;

Doing a gauge transformation has nothing to do with collapse of the wave function. They are very different things for many reasons. Mentioning gauge invariance was meant to argue that the wave itself is ambiguous in its definition (gauge ambiguity). A further reason why we can't measure it.

43 minutes ago, AIkonoklazt said:

The "collapsing" to me is just a description of what's seen [...]

Well, not of what's seen. Of what could be, if somebody took notice, happend to be there, or came later and checked. You can rest assured when the tree falls in the forest it does make a sound, even though nobody's there to hear it.

 

Link to comment
Share on other sites

1 hour ago, AIkonoklazt said:

attributing that aforementioned big chunk of the wave disappearing to a "collapse" just feels to me like a case of the tail wagging the dog; The "collapsing" to me is just a description of what's seen (because that's the only thing that could be seen) instead of something "being collapsed."

It's not that it disappears. The probability of one state goes to 1 - we observe it in that state - and the rest go to zero. Probability is conserved; it has to add to 1. 

Link to comment
Share on other sites

57 minutes ago, joigus said:

Again? Sorry, you said we can a few times.

 

I stated its impossibility multiple times:

Quote

If we could actually measure all the values (of course, not possible)

Quote

 

If, as I've mentioned earlier, we can do the absolute impossible and measure all values of this wave instead of one, then it's not going to be a dot.

How? You can't. It's impossible.

 

 

Edited by AIkonoklazt
Link to comment
Share on other sites

On 12/5/2023 at 8:37 PM, AIkonoklazt said:

If we could actually measure all the values (of course, not possible) then there is no collapse. Thus my previous answer of "it's because of the limitation of the measurement," or the limitation of the measuring device, or ultimately just the limitation of the interaction between the measuring device and the "wave" being measured.

Let's take a simple case of only two possible values, e.g., electron spin. A measurement in UP/DOWN basis results in either UP or DOWN. Let's take an electron in the superposition state \( (\frac 1 {\sqrt 2}, \frac 1 {\sqrt 2}) \). Immediately after measuring say UP, its state is \( (1, 0) \). How can the limitations above explain this transformation?

Edited by Genady
Link to comment
Share on other sites

20 hours ago, Genady said:

Why would I read a Scientific American Blog?

 

20 hours ago, studiot said:

Becasue it's by Deepak Chopras's mates ?

 

I'm sorry Luc, that blog reminds me of the early days of the science of Geology.

Lots of discoveries were made by people whose motivation was to prove the glory of God.

 

Are-these articles better suited? Both from Nature!

Hope that they are not from Deepak's mates

I need guidance in interpretation; if you have time for this

The first appears to show human choices in QM (although weak; it think; may be an artifact)

And the second one appears to make use of a random number generator to ensure independance from human choices to close-off a loophole in the Bell test.

Right?

https://www.nature.com/articles/s41586-018-0085-3

https://www.nature.com/articles/s41586-023-05885-0

 

 

Link to comment
Share on other sites

10 hours ago, joigus said:

Sorry, my bad. If we did the impossible, what would be possible?

Observing without the observer effect. Certain interpretations of the observer effects would be shown correct, while others debunked. (probably already done both through other means, but could add this on top. I'm not well-informed on this subject.)

7 hours ago, Genady said:

Let's take a simple case of only two possible values, e.g., electron spin. A measurement in UP/DOWN basis results in either UP or DOWN. Let's take an electron in the superposition state (12‚ąö,12‚ąö) . Immediately after measuring say UP, its state is¬†(1,0) . How can the limitations above explain this transformation?

I don't know. Let's take something in my field. If you use an oscilloscope to measure a signal waveform, the scope necessarily becomes part of the circuit it's measuring. I don't know the quantum physical interaction is between the measured and the measuring apparatus, but it may have something to do with how the act of measurement is fusing observer+observed into one system.

Link to comment
Share on other sites

6 minutes ago, AIkonoklazt said:

Observing without the observer effect.

One way could be a filtering measurement, like the ones I suggested. All the interactions had to happen as consistency conditions for the particle to be "summoned" within the region of interest. So you can rest assured the spin, momentum, kinetic energy (a "diagonal" function of momentum if the particle is a free particle) have the values that are consistent with the experimental setup. You don't have to "touch" the particle ever again.

Other term to look up would be "weak measurement" (which has become quite fashionable as of late, I think).

People have been working on this for quite some time now, so I'm probably quite rusty on this.

Link to comment
Share on other sites

6 hours ago, Luc Turpin said:

 

Are-these articles better suited? Both from Nature!

Hope that they are not from Deepak's mates

I need guidance in interpretation; if you have time for this

The first appears to show human choices in QM (although weak; it think; may be an artifact)

And the second one appears to make use of a random number generator to ensure independance from human choices to close-off a loophole in the Bell test.

Right?

https://www.nature.com/articles/s41586-018-0085-3

https://www.nature.com/articles/s41586-023-05885-0

 

 

As far as I can understand from the abstracts, they are scientific. However, they don't seem to have a relation to this thread's topic.

Link to comment
Share on other sites

16 hours ago, Luc Turpin said:

Are-these articles better suited? Both from Nature!

Hope that they are not from Deepak's mates

I need guidance in interpretation; if you have time for this

The first appears to show human choices in QM (although weak; it think; may be an artifact)

And the second one appears to make use of a random number generator to ensure independance from human choices to close-off a loophole in the Bell test.

Right?

https://www.nature.com/articles/s41586-018-0085-3

https://www.nature.com/articles/s41586-023-05885-0

 

9 hours ago, Genady said:

As far as I can understand from the abstracts, they are scientific. However, they don't seem to have a relation to this thread's topic.

Indeed +1.

 

Luc, there are always those who try to 'push the envelope'.
This is good and part of the Ccientific Method.

But the successful ones which eventually add something to body of knowledge generally know the core of the subject they are hoping to expand.

 

And I thought that it was the core of Quantum Mechanics you are hoping the get to grips with not the fringes.

There is a whole Wikipedia article on the subject of Bell's Tests with quite a list of isolated esoteric experiments that generally have not been independently repeated.

It is this repeatability that is important so the as near as every time we go to the cupboard the same thing happens, rather than the odd instance where the mouse has got into the cookie jar.

 

Take entanglement. There are questions, but this happens every day all over the universe in an entirely predictable way.

We rely on it, our existence relies on it. This is the entanglement of two electrons in a molecular orbital forming a bond.

 

This exploration of conceivable, but fringe, effects has been going on for a long time in many disciplines.

In classical mechanics, it is known that a spinning top has two stable positions  - upright and upside down.
And that it is theoretically possible for the spinning top to spontaneously flip between these states.
Such flipping has been invoked to explain geological process from Noah's flood to plate techtonics on Earth, but we have never found evidence that this is what actually happened.

However such flipping has been observed as a frequent and regular occurence in the sub atomic world of bonding orbitals so is not 'pie in the sky'

 

 

 

Link to comment
Share on other sites

6 minutes ago, studiot said:

 

And I thought that it was the core of Quantum Mechanics you are hoping the get to grips with not the fringes.

 

Point well taken! We will keep to the basic ideas of QM here! And contemplate presenting elswhere fringe ideas! Let the learning continue!

Know so little and learning so much that I often get lost in all of it!

Link to comment
Share on other sites

1 hour ago, Luc Turpin said:

Point well taken! We will keep to the basic ideas of QM here! And contemplate presenting elswhere fringe ideas! Let the learning continue!

Know so little and learning so much that I often get lost in all of it!

I have posted core information several times, but you seem to have little to ask or discuss about it.

Lasr time spin and entanglement were new. Both are key quantum features.

 

I have also drawn on the classical world, where possible, as it is easier and also easier to not be suprised by parallel features there.

Edited by studiot
Link to comment
Share on other sites

1 minute ago, Genady said:

This is where I get lost.

Really? It's lame, but it's a play with words.

Just now, joigus said:

Really? It's lame, but it's a play with words.

Sorry, I meant a "play on words".

Was that the problem?

It's more of an alliteration, now that you mention it.

Link to comment
Share on other sites

1 minute ago, Genady said:

What envelope?

Quote
push the envelope
  1. (informal) to go beyond the limits of what is allowed or thought to be possible
    • He is a performer who consistently pushes the envelope of TV comedy.

As used by @studiot:

2 hours ago, studiot said:

Luc, there are always those who try to 'push the envelope'.

 

Link to comment
Share on other sites

25 minutes ago, studiot said:

I have posted core information several times, but you seem to have little to ask or discuss about it.

 

Because I am all over the place!  Will now focus more! Althought, I still have made attempts with past posts to summarize ideas that you presented.  As you might have noticed, I am more a summary king of person rather than a detailed one! It has its ups and down! Again, I 

 

1 minute ago, Genady said:

What envelope?

As in pushing the envelope; meaning testing limits and trying out new, often radical ideas, which I will be doing in other parts of Science Forums. 

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.