Watching the double-slit experiment affects the results?

[bhobba]

Reality doesn't exist until it is looked at experimentalists say
http://www.sciencedaily.com/releases/2015/05/150527103110.htm

There has never been an experiment that disagrees with the QM formalism. Not one - ever. If there was it would mean an instant Nobel prize because you have overturned one of our foundational theories. In the formalism what's going on when not observed the theory is silent about. We have interpretations where its exists independent of observation and ones where it isn't and even ones where people argue what it means. Without even reading you link (other science advisers have so I won't bother) I can tell you it is wrong if its saying that.

Thanks
Bill

 

[bhobba]

Our experiment confirms Bohr’s view that it does not make sense to ascribe the wave or particle behaviour to a massive particle before the measurement takes placehttp://www.nature.com/nphys/journal/v11/n7/full/nphys3343.html#ref1

Since Dirac published (probably sooner but then for sure) his transformation theory (its the theory that basically goes by the name QM today) at the end of 1926 it has been known that this wave particle stuff is a crock of the proverbial - it is neither wave or particle - it is quantum stuff. If you have an observation where it behaves LIKE a wave what's going on when not observed QM says nothing. Same if it behaves LIKE a particle. Its built into the foundational axioms of QM. You can't escape it.

Please, please be careful of anything that uses quotes from the early founders of QM - things have moved on a lot since then:
http://www.fisica.ufmg.br/~dsoares/cosmos/10/weinberg-einsteinsmistakes.pdf

As Weinberg explains, while it is generally said Bohr won the magnificent Einstein-Bohr debates they were in fact both wrong. Those debates are compelling reading for anyone interested in physics but are of historical interest - we understand things better now.

Thanks
Bill

 

[bhobba]

You seem to assume computers are somehow made of classical particles and exist apart of anything quantum but this is demonstrably wrong.

That is not assumed at all.

The modern conception of observation is its a purely quantum phenomena due to the entanglement of what's being observed with what's doing the observing. There is broad agreement that's all that's going on. Do not be fooled by long drawn out discussions on this forum about certain subtleties in this such as the so called factorisation problem.

In fact in modern times its becoming clear entanglement is the aspect of QM that separates it from classical physics:
http://arxiv.org/abs/0911.0695

Thanks
Bill

 

[bhobba]

The above means the same as -- 'measurements are almost always done by a collapsed wavefunction(aka 'computer') with results being analyzed only at a later time' ... this is explaining the unexplained by utilizing the unexplained to explain the unexplained. AKA circular reasoning. Hence it can not be an argument against the OP.

A computer is not a collapsed wave-function - where you get such from has me beat. In fact collapse isn't even part of the QM formalism - only some interpretations.
https://en.wikipedia.org/wiki/Interpretations_of_quantum_mechanics

Before going down this conciousness path I strongly suggest you read the source that started it all - Von Neumann's - Mathematical Foundations of Quantum Mechanics. His analysis falls to pieces with the modern technology of the computer and is reduced to almost laughable status. Note almost here - it is impossible to refute conciousness being involved in the same way its its impossible to refute solipsism. But pretty much everyone exposed to it rejects it which is why its a very backwater interpretation these days.

Thanks
Bill

 

[bhobba]

On the other hand, yep, no matter what device we use to run an experiment, someone eventually will have to look at the results of that experiment. .

That's not true and in fact leads to conciousness being involved as quite absurd.

Imagine a double slit where the results is recorded to computer. The results are copied a million times into memory and separated by vast distances. If you adopt conciousness being involved you will have to say all those copies collapse the moment any of those results are viewed. You can probably create a consistent world view along those line - but a very very weird one.

Thanks
Bill

 

[Jakaha]

OK, sorry, I must have mixed up a couple of videos in my mind.

This particular video only says that the decision to observe may be delayed AFTER the photon has passed the slits but BEFORE it hits the result screen.

around 17:27

 

[bhobba]

This particular video only says that the decision to observe may be delayed AFTER the photon has passed the slits but BEFORE it hits the result screen.

In fact its a demonstration of the modern view of observation and entanglement/decoherence being synonymous. All they show is in simple cases decoherence can be undone. If conciousness etc was actually involved you wouldn't expect that.
https://www.physicsforums.com/threa...and-the-delayed-choice-quantum-eraser.623648/

Thanks
Bill

 

[Atla]

That's not true and in fact leads to conciousness being involved as quite absurd.

Imagine a double slit where the results is recorded to computer. The results are copied a million times into memory and separated by vast distances. If you adopt conciousness being involved you will have to say all those copies collapse the moment any of those results are viewed. You can probably create a consistent world view along those line - but a very very weird one.

Thanks
Bill

I'm not saying that consciousness is involved, nor do I say that collapse is real - the idea of "collapse" is still pure unexplained sci-fi, nothing else.

On the other hand, it's also perfectly possible to have millions of copies of the results, and they are still in a "superposition" state or whatever from every human's point of view. It is a very very weird world view, but the only logical conclusion. However I'm also not saying that looking at them collapses them all, and for everyone.

 

[Strilanc]

OK, sorry, I must have mixed up a couple of videos in my mind.

This particular video only says that the decision to observe may be delayed AFTER the photon has passed the slits but BEFORE it hits the result screen.

around 17:27

Wow, that's... really bad. They actually have an animation of a person opening their eyes off to the side of the experiment, and the waves wink into particles as a result. The actual experiment is nothing like that at all. It's more like... deciding whether or not to throw away or use the information needed to split the blips making up the non-interference-pattern into two groups where each group contains an interference pattern.

 

[bhobba]

On the other hand, it's also perfectly possible to have millions of copies of the results, and they are still in a "superposition" state or whatever from every human's point of view. It is a very very weird world view, but the only logical conclusion. However I'm also not saying that looking at them collapses them all, and for everyone.

No one is saying conciousness causes collapse isn't a valid view - it is. That however is different from saying it is involved.

Thanks
Bill

 

[Bruno81]

That is not assumed at all.

It is.

The modern conception of observation is its a purely quantum phenomena due to the entanglement of what's being observed with what's doing the observing.

Modern? We are not discussing fashion and entaglement helps nothing in resovling the MP.

There is broad agreement that's all that's going on. Do not be fooled by long drawn out discussions on this forum about certain subtleties in this such as the so called factorisation problem.

That's wrong, there isn't agreement of any sort. That's wishful thinking.

In fact in modern times its becoming clear entanglement is the aspect of QM that separates it from classical physics:
http://arxiv.org/abs/0911.0695

Aspect. I am an aspect of shoes manufacture(i wear shoes) but i am not the factory.

 

[Bruno81]

In fact its a demonstration of the modern view of observation and entanglement/decoherence being synonymous. All they show is in simple cases decoherence can be undone. If conciousness etc was actually involved you wouldn't expect that.
https://www.physicsforums.com/threa...and-the-delayed-choice-quantum-eraser.623648/

Thanks
Bill

Can be undone if which path info is available.

 

[Bruno81]

computer is not a collapsed wave-function - where you get such from has me beat.

Are you a physicist? What is a 'computer' from the point of view of qft?

 

[bhobba]

It is.

You wrote:

You seem to assume computers are somehow made of classical particles and exist apart of anything quantum but this is demonstrably wrong.

Everything is quantum and all I have been saying is based on that.

The rest of your reply shows a distinct lack of knowledge of modern QM (eg that decoherence has nothing to do with the MP is - well way off the mark - it doesn't solve it but explains a number of its parts), but let's pin this fundamental issue down first ie why you think I am making that assumption.

In case you are interested in getting such knowledge I suggest the following:
https://www.amazon.com/dp/3540357734/?tag=pfamazon01-20

It for example carefully explains the measurement problem. It has a number of parts - decoherence explains all but one - the problem of outcomes.

Thanks
Bill

 

[bhobba]

Are you a physicist? What is a 'computer' from the point of view of qft?

I have a Bachelors degree in applied math and functional analysis. I am self taught in physics from many sources. Of relevance to this thread are the following:
https://www.amazon.com/dp/9810241054/?tag=pfamazon01-20
https://www.amazon.com/dp/3540357734/?tag=pfamazon01-20

Precisely why do you think QFT has anything to do with describing macro objects with QM? Its obvious it has nothing to do with it, but if you have a reason I am all ears.

How do classical objects emerge from the quantum? Interaction with the environment:
http://vvkuz.ru/books/zurek.pdf

Thanks
Bill

 

[Nugatory]

the idea of "collapse" is still pure unexplained sci-fi, nothing else.

It's also not a required part of the theory of quantum mechanics. It's one way of using natural language to talk about what the mathematical formalism is telling us, and it is very convenient for reasoning about some systems (single photon encounters polarizer, single particle flies through Stern-Gerlach device) but gets in the way when reasoning about other systems (spacelike-separated measurements of entangled systems).

 

[Bruno81]

To the OP - this will go round in circles till forever because there is just ONE thing that is science here - the mathematical formalism of quantum theory.

Unfortunately, it's completely incomprehensible and taken at face value hints at solipsism/idealism or some other weird -ism.

The unfortunate effect of this situation is that a handful of useful equations that give tested predictions are garnered with one million volumes of BS assumptions, theories and wild speculation that sometimes pass for science and established fact to the untrained and gullible eye. While the formalism is likely 100% correct and will remain so for a considerable amount of time, the theories surrounding it are likely all 100% wrong from start to finish and will remain so for a considerable amount of time.

 

[DrClaude]

I think this thread has run its course.

Thread closed.