Does Conscious Observation Affect the Outcome of the Double-Slit Experiment?

[bobos1997]

Hello there,

My question is: Is there a double slit-experiment done with all of the measuring equipment in place and all of the equipment activated but without a conscious observer? Proving there is no differentation pattern regardless of a conscious observer.

Thanks in advance

 

[Nugatory]

My question is: Is there a double slit-experiment done with all of the measuring equipment in place and all of the equipment activated but without a conscious observer? Proving there is no differentation pattern regardless of a conscious observer.

Not only has that been done, it has never been done any other any way.

First consider the ordinary classical double-slit experiment, the thing that Thomas Young did back before the battle of Waterloo and more than a century before quantum mechanics was discovered: We shine coherent light on the barrier with two slits and an interference pattern appears on the screen behind it. This is easily explained; light is electromagnetic waves and waves interfere when there are two paths from source to target. There's no quantum mechanics involved, and because humans can see light Young was able to look directly at the screen and see the interference pattern. Obviously his observing the experiment didn't make the interference pattern go away (and it would be somewhat bizarre to think that it might).

But that's not the quantum mechanical double-slit experiment.

In the quantum-mechanical experiment, we send particles (usually photons, but it's been done with electrons) one at a time towards the barrier. Each particle hits the screen at a single point; the interference pattern only appears over time as we find that more particles strike some regions of the screen than others. However, we humans cannot see a single electron or a single photon striking the screen so we cannot observe any of this. Instead we have to use some sort of non-conscious equipment to record where each particle lands. This equipment may be an array of particle detectors, or it may be a singe particle detector that we move around to see where the rate of particle arrival is highest; when the experiment was first done we used ordinary photographic film that sent off to be developed after it had been struck by an interesting number of particles. Thus, the results are all there and completely recorded before any conscious observer has gone anywhere near them.

 

[bobos1997]

Thanks you,

So just to get this clear. Its the obtaining of the data that makes the wave collapse in the double slit experiment?
Has there ever been an experiment where the data, stating through which slit the particle actually went, was deleted before the particle hit the screen? If so what where the results?

I am sorry if this is bothering someone it is just so confusing.

 

[Nugatory]

It won't be so confusing if you remember that just about everything you read about the role of consciousness is wrong - it's an urban legend that started early in the 20th century and like so many urban legends has taken on a life of its own.

Its the obtaining of the data that makes the wave collapse in the double slit experiment?

You'll need a much more precise definition of exactly what you mean by "obtaining the data" before that question can be answered with a simple yes or no.
However, with some handwaving... If something thermodynamically irreversible (like a grain of silver iodide in a sheet of photographic film being exposed and changing state, or a photon detector sending a pulse of electricity down a wire, or a the measurement results being burned into a CD-ROM that we then drop into a shredder) happens, then it's happened whether someone is watching or not and it can't be made to unhappen.

 

[bobos1997]

Hmm I see, but why is it wrong if I may ask?

This video has me thinking it is not wrong...
My thoughts are based on the first 3minutes of the video (but i have watched all of it).



I am not sure if the video is bullshit or if I have misunderstood the video. But in either of these cases please tell me why and possibly present some proof.
I am not trying to taunt anyone...

 

[Nugatory]

Hmm I see, but why is it wrong if I may ask?

Because it matches neither the predictions of the theory as we understand it today nor any experiment that has actually been done. It does match the way some physicists understood the theory almost a century ago, but we've learned a fair amount since then.

This video has me thinking it is not wrong...

Delayed choice eraser experiments are one of the reasons why I said that "obtaining the data" must be very precisely defined. You can't erase thermodynamically irreversible events such as a detector clicking or a spot appearing on a piece of photographic film.

You also can't understand quantum mechanics from dubious internet videos, which is why Physics Forums has its rule about acceptable sources. Although there is no substitute for a real textbook with real math, there are some books that cover some of this ground gently and without the math. Try Giancarlo Ghirardi's "Sneaking a look at god's cards" for an overview of QM and David Lindley's "Where does the weirdness go" for an explanation of quantum decoherence and why we are able to discard the idea that consciousness was involved in collapse.

 

[bhobba]

My question is: Is there a double slit-experiment done with all of the measuring equipment in place and all of the equipment activated but without a conscious observer? Proving there is no differentation pattern regardless of a conscious observer.

Nugatory is correct - you can't really do it any other way.

But in the sense I think you mean it - yes - many times eg you have a photographic plate that registers the photons as they arrive one at a time (things are arranged so only at the most one photon is in the apparatus at any time). Days later you view the pattern that built up after the plate is developed.

Thanks
Bill

 

[PeterDonis]

Thread closed for moderation.

Edit: Some off topic posts have been deleted and the thread has been reopened.

 

[nnope]

Try Giancarlo Ghirardi's "Sneaking a look at God's cards" for an overview of QM and David Lindley's "Where does the weirdness go" for an explanation of quantum decoherence and why we are able to discard the idea that consciousness was involved in collapse.

This whole consciousness story is super annoying. To put it to a close in my mind, consciousness does not play a role in QM and although some scientists may have believed so in the past out of misunderstanding It can no longer hold in today's understanding of QM, right?
I want to confirm this because I'm tired of reading posts of people claiming this and then going on to make it religious.

Thanks!

 

[Mentz114]

This whole consciousness story is super annoying. To put it to a close in my mind, consciousness does not play a role in QM and although some scientists may have believed so in the past out of misunderstanding It can no longer hold in today's understanding of QM, right?
I want to confirm this because I'm tired of reading posts of people claiming this and then going on to make it religious.

Thanks!

Read posts #4 , #6 and #7 above and rest assured. I agree that it is annoying but the popular videos and books promote the 'mystical' interpretations because those draw more viewers.

 

[nnope]

Read posts #4 , #6 and #7 above and rest assured. I agree that it is annoying but the popular videos and books promote the 'mystical' interpretations because those draw more viewers.

Im relieved thanks heaps!

 

[bobos1997]

Thank u for all the comments.

The point of discussion seems to be, that one side states that the creation of information/data that lasts in time is the factor that causes the wave to collapse and the other side states it is the observation of this data that causes the wave to collapse.

This seems to be somewhat the same as the ancient philosophical thought experiment: If a tree falls in a forest and no one is around to hear it, does it make a sound? With the major difference that in this discussion the abstract matter of the creation of data/information that lasts in time, sticking to the analogy, creates the soundwaves. In addition to this the laws of quantum-physics are somewhat non-instinctive. One could presume these two differences make people more likely to pick the side which states there is 'no sound' until it has been observed by a conscious being

When there is data/information that lasts in time, it can, at one point be observed by a conscious being and when something is observed by a conscious being it is always a form of data/information. This implies that that proving or disproving either theorie is impossible.
Therefore it is true that rationally c.q. not using a form of argumentum ad verecundiam that both theories are equally plausible.

Both theories have appealing properties. The 'theorie of consciousness' is constant and therefore never has to be changed. In addition it gives more cosmological 'meaning' to our existence as conscious beings. The 'theorie of data/information' on the other side fits better within the current scientific paradigma which has brought us as a species great knowledge and also gives us a way of looking forward into finding out more about what exactly is going on in this experiment.

Personally I am inclined to choose the data/information perspective, for without it, physics would not exist.
I now realize this reply and this topic do not belong on the physics forum, but my mind has, after months of thinking, nevertheless been put to rest. Thank you all!

P.S.
Despite my personal opinion I realized the consciousness side shines a light on maybe the most famous philosofical statement, which in addition to the 'consciousness theorie' is undeniably true.

''I know that I know nothing''
Socrates

 

[bhobba]

The point of discussion seems to be, that one side states that the creation of information/data that lasts in time is the factor that causes the wave to collapse and the other side states it is the observation of this data that causes the wave to collapse.

I don't know how many times it has been said, collapse is an interpretational thing - even defining it exactly is no easy task - we had a discussion amongst the science advisers and the best we could come up with was the Born Rule which really isn't saying much. Its the 'meaning' behind the Born Rule that determines if you have collapse or not and that meaning is just a matter of opinion - its not scientific.

Here is what causes a 'point' to appear of the photographic plate. The state at the plate interacts with it and via dehoherence it leaves a 'mark' on the plate. The position of the mark can't be predicted - we can only predict probabilities. The central mystery, and even if its an actual mystery is debatable, is exactly how is a particular position of that mark selected - we don't know. Me and many others think it's simply a primitive of the theory - all theories have them, this one is no better or worse than any other in physics or mathematical modelling in general. It's just how nature is, but opinions vary. Each interpretation has it's own take - read about them if you are interested in that sort of thing - they all have value in that they all shed some light on the formalism - but none are better, or worse, than any other - some like consciousness causes collapse simply grate on a lot of people (I am one - but it's not scientific - if it is in accord with experiment - that's all that counts) - its not something that can be decided by the only gold standard of science - experiment.

Basically your musings are just personal opinions on metaphysically how you view the world and relate how you judge various 'interpretations'. You are allowed to do that, but its not science - its more like philosophy which is not what this forum discusses.

Thanks
Bill