A question about the observer effect

[PyramidHead]

I can't seem to find an answer about what exactly the observer effect means in the context of quantum mechanics. The popular science articles always seem to emphasize the "observer" part, but when I dig a little deeper, it seems to be less about observing and more about measuring. When I measure something visually, for example, whether I use my eyes or a camera lens, I take advantage of photons that strike nearby surfaces before being picked up by the detector. This physical interaction between the photons and whatever quantum phenomenon is being measured is what manifests as a collapse of the wave function, as I understand it. By my estimation, turning off the camera or averting my eyes should not make any difference to the outcome, as long as the photons that I would have used to make my measurement are still bouncing off of surfaces and interfering with the quantum phenomenon. Is this an accurate portrayal of the observer effect? In his newly translated book Ball Lightning, Cixin Liu (an author who is usually highly rigorous in his physical accuracy) seems to disagree, and implies that it is not the medium of measurement but the observational apparatus itself that causes wave function collapse. That is, in a well-lit outdoor area, a quantum phenomenon will be indeterminate if everyone closes their eyes or turns their backs, but will collapse into a particle if somebody is surreptitiously filming the experiment. Isn't this just nonsense? Or am I not giving quantum weirdness enough credit?

 

[steve_bank]

It is straightforward. A cup of cold water is warming to room temperature. If you put in a glass thermometer to measure water temperature you measure not just water, but a system comprised of the thermometer, cup, and water.

Measuring a voltage is similar. Put a digital meter across a resistor and the input resistance of the meter is in parallel with the resistor changing the voltage slightly. At the macro level we can usually access the measurement induced errors and often minimize them to the point it is not significant.

There are tiny thermal sensors with a small mass to measure the temperature of small objects. To avoid ditrbing the water temp in the cup of water we'd use a very small low mass sensor, much lower than the mass of the water.

At the quantum level it is different when dealing with particles. Using a particle to test a particle. Like shooting a bullet at a bullit. In QM experiments there can be a question as whether the observed effect is actual, or if it is induced by the intrusion of a measurement.An inability to separate measurement and observation. Such as the slit diffraction experiment.

The general conclusion is that there is no such thing as an independent observer. Physical observation requires energy transfer and a disturbance of the observation.

 

[steve_bank]

Imagine a rock out in the open. The atmosphere and the rock form a thermodynamic system.

Light from the sun eners the atmospher and hits the rock reflecting light. There are losses in the atmospher and absorption in the rock. The system output is reflected light.

If you put an optical sensor in the path of the reflected light you are disturbing the system If you step into the reflected light the photons absorbed by youre eyes are suntracted from the system output.

Schrödinger's Cat. He devised the thought exoeriment to show the absurdity of interpretaions of QM. They all become mryaphysical speculation. Does something exist if I do not look at it or think about it? A lot is made out of interpreting QM.

https://en.wikipedia.org/wiki/Schrödinger's_c

To further illustrate, Schrödinger described how one could, in principle, create a superposition in a large-scale system by making it dependent on a quantum particle that was in a superposition. He proposed a scenario with a cat in a locked steel chamber, wherein the cat's life or death depended on the state of a radioactive atom, whether it had decayed and emitted radiation or not. According to Schrödinger, the Copenhagen interpretation implies that the cat remains both alive and dead until the state has been observed. Schrödinger did not wish to promote the idea of dead-and-alive cats as a serious possibility; on the contrary, he intended the example to illustrate the absurdity of the existing view of quantum mechanics.[1] However, since Schrödinger's time, other interpretations of the mathematics of quantum mechanics have been advanced by physicists, some of which regard the "alive and dead" cat superposition as quite real.[8][5] Intended as a critique of the Copenhagen interpretation (the prevailing orthodoxy in 1935), the Schrödinger's cat thought experiment remains a defining touchstone for modern interpretations of quantum mechanics. Physicists often use the way each interpretation deals with Schrödinger's cat as a way of illustrating and comparing the particular features, strengths, and weaknesses of each interpretation.

Schrödinger wrote:[1][10]

One can even set up quite ridiculous cases. A cat is penned up in a steel chamber, along with the following device (which must be secured against direct interference by the cat): in a Geiger counter, there is a tiny bit of radioactive substance, so small, that perhaps in the course of the hour one of the atoms decays, but also, with equal probability, perhaps none; if it happens, the counter tube discharges and through a relay releases a hammer that shatters a small flask of hydrocyanic acid. If one has left this entire system to itself for an hour, one would say that the cat still lives if meanwhile no atom has decayed. The first atomic decay would have poisoned it. The psi-function of the entire system would express this by having in it the living and dead cat (pardon the expression) mixed or smeared out in equal parts.

 

[blastula]

It's the effect of any physical interaction with the object. It's a poorly named phenomenon, probably responsible for most of the quantum woo peddling.

 

[Juma]

Its not about generic measurement interference (as in thermometer adds to the mass of what should be measured etc) Its about the problem of ”wave collapse”.
At quantum scale phenomena moves/distributed as waves but interacts as particles.
When you interacts some properties becomes fixed and others indeterminated.
A short example:
As if you measure magnetc spin of an electron you can only measure it in one direction: let call that direction the y-axis, it becomes indetermined at directions ortogonal to this (x and z axises).
So if you
1) measure along Y and only picks the particles a specific spin (up or down)
2) measure along X and picks the particles with spin right
3) then measures again along Y you will have an even distributuon of up and down

Similar behaviour can be shown with position an velocity.
If the position is measured the velocity to acertain degree becomes undetermined to a corresponding degree.


The problem with this ”wave collapse” is that it cannot be observed.

So one (more or less woo) theory is that the collapse of the wave is identical to what we experience with our mind.

 

[fromderinside]

Oh come on. The 'wave' is not knowing the status of the cat. We know there is a cat and a box and poison. We can't see (know) whether the cat is dead until we open the box. Wave collapse may not be observed but it can be timed to after the closing of the box to before the moment of the opening of the box meaning. The fact of the cat's death must be a possibility for the entire time the box is closed, a range of possibility, a wave.

 

[PyramidHead]

It's the effect of any physical interaction with the object. It's a poorly named phenomenon, probably responsible for most of the quantum woo peddling.

So, if I'm understanding you, the presence of an object like a camera or a human being in the system is no more special (in terms of its ability to interfere with a quantum particle) than another object of similar size but lacking the ability to "observe"?

 

[Bronzeage]

It's the effect of any physical interaction with the object. It's a poorly named phenomenon, probably responsible for most of the quantum woo peddling.

So, if I'm understanding you, the presence of an object like a camera or a human being in the system is no more special (in terms of its ability to interfere with a quantum particle) than another object of similar size but lacking the ability to "observe"?

Everything we wish to measure is compared to something of a known quantity. This is easy at scales with which we are familiar. A tape measure doesn't change the length of anything, in most cases. One might try to measure a spider web thread, but touching the thread distorts it, so we hold the tape very close and estimate the measurement. No imagine the thread is waving in the wind. We have to move the tape in the same pattern as the moving thread. The more precisely we want to measure(precise means smallest unit of measurement possible within the system), the greater the chance we distort the thread. In the end, whatever measurement we observe, there is a chance it's not as accurate(repeatable measurement of same quantity) as the numbers tell us.

 

[PyramidHead]

It's the effect of any physical interaction with the object. It's a poorly named phenomenon, probably responsible for most of the quantum woo peddling.

So, if I'm understanding you, the presence of an object like a camera or a human being in the system is no more special (in terms of its ability to interfere with a quantum particle) than another object of similar size but lacking the ability to "observe"?

Everything we wish to measure is compared to something of a known quantity. This is easy at scales with which we are familiar. A tape measure doesn't change the length of anything, in most cases. One might try to measure a spider web thread, but touching the thread distorts it, so we hold the tape very close and estimate the measurement. No imagine the thread is waving in the wind. We have to move the tape in the same pattern as the moving thread. The more precisely we want to measure(precise means smallest unit of measurement possible within the system), the greater the chance we distort the thread. In the end, whatever measurement we observe, there is a chance it's not as accurate(repeatable measurement of same quantity) as the numbers tell us.

That makes perfect sense to me. My confusion stemmed from the novel I referred to in my OP, written by an author who usually is highly rigorous in his suggestions about physics even when they are outlandish. It's disappointing that he took the woo route in his description of the observer/measurement effect in this latest book, it took me out of the experience in a small way upon reading that part (as I wasn't sure if it was just a misunderstanding of mine) and now a big way in retrospect, knowing that his portrayal was just nonsense. I know bilby is a fan of Cixin Liu, so I'd be curious to hear his views on the book, and that aspect in particular, if he's read it.

 

[steve_bank]

Books mixing physics and a new form of mysticism began in the 70s.

QM is a set of mathematical processes and models that provide useful real results. Transistors and lasers. Beyond that it is speculation and philosophy.

When people hear 'Wave Equation; they jump yo the image of a physical wave propagating. It ios just math, no more mysterious than the Fourier Transform.

In past threads people claim QM proves many things, including life after death. Virtual particles prove something can come from nothing.

Star Trek influenced many people. It and other sci fi created false impressions of scientific concepts. The guy who played Riker said the cast referred to the science dialogue as 'science babble'.

 

[PyramidHead]

Books mixing physics and a new form of mysticism began in the 70s.

QM is a set of mathematical processes and models that provide useful real results. Transistors and lasers. Beyond that it is speculation and philosophy.

When people hear 'Wave Equation; they jump yo the image of a physical wave propagating. It ios just math, no more mysterious than the Fourier Transform.

In past threads people claim QM proves many things, including life after death. Virtual particles prove something can come from nothing.

Star Trek influenced many people. It and other sci fi created false impressions of scientific concepts. The guy who played Riker said the cast referred to the science dialogue as 'science babble'.

Yeah, or "tech talk" inserted into the script. I get that. I just wish there was a better consensus about stuff like the quantum eraser and delayed choice experiments, where the "which path"-determining event at least appears to be connected to the act of observing a measurement that was previously taken, and not the prior taking of the measurement itself (although my understanding of these experiments is very rudimentary).

 

[steve_bank]

Books mixing physics and a new form of mysticism began in the 70s.

QM is a set of mathematical processes and models that provide useful real results. Transistors and lasers. Beyond that it is speculation and philosophy.

When people hear 'Wave Equation; they jump yo the image of a physical wave propagating. It ios just math, no more mysterious than the Fourier Transform.

In past threads people claim QM proves many things, including life after death. Virtual particles prove something can come from nothing.

Star Trek influenced many people. It and other sci fi created false impressions of scientific concepts. The guy who played Riker said the cast referred to the science dialogue as 'science babble'.

Yeah, or "tech talk" inserted into the script. I get that. I just wish there was a better consensus about stuff like the quantum eraser and delayed choice experiments, where the "which path"-determining event at least appears to be connected to the act of observing a measurement that was previously taken, and not the prior taking of the measurement itself (although my understanding of these experiments is very rudimentary).

You are describing the measurement and interpretation problem at the quantum level. The slit particle diffraction experiment led to a duality in the models. With EM radiation when you look for a wave you find a wave, when you look for a partcl you get a photon. Is the duality a measurement limitation and the radiation is something different than we imagine, or does the radiation have a real duality? Unanswerable. We are limited by instrumentation.

Science begins with inaginatin and dreams. What we do not usually see is all then ideas that failed.

I think it was AC Clark or Asiimov who predicted communication satellite systems in the 40s. The original ST had small handled wireless devices, handheld computers,diagnostic medical technology, voice recognition and computer generated speech. Language translators and so on.

I watched a show on the movie First Contact. A team of scientists provided the science background for the alien wormhole transportation system. Knowing scfii is fiction doesn't mean you can't enjoy it, it requires the willing suspension of disbelief.

 

[steve_bank]

Its not about generic measurement interference (as in thermometer adds to the mass of what should be measured etc) Its about the problem of ”wave collapse”.
At quantum scale phenomena moves/distributed as waves but interacts as particles.
When you interacts some properties becomes fixed and others indeterminated.
A short example:
As if you measure magnetc spin of an electron you can only measure it in one direction: let call that direction the y-axis, it becomes indetermined at directions ortogonal to this (x and z axises).
So if you
1) measure along Y and only picks the particles a specific spin (up or down)
2) measure along X and picks the particles with spin right
3) then measures again along Y you will have an even distributuon of up and down

Similar behaviour can be shown with position an velocity.
If the position is measured the velocity to acertain degree becomes undetermined to a corresponding degree.


The problem with this ”wave collapse” is that it cannot be observed.

So one (more or less woo) theory is that the collapse of the wave is identical to what we experience with our mind.

It is position and momentum. The UP applies to any set of conjugate variables.

The wave function is a probability distribution. 'Collapsing' is metaphoric.

Flip a coin in the air. A wave function describes the probilities. When the coin hits the ground into a measurable state the wave function has collapsed into one of possible states.

10 light small balls are floating around in a column with airflow. There is a probability of a given state at any time, The act of measuring the state of the balls at any time selects the state. Measurement collapses the wave function.

 

[Jokodo]

In past threads people claim QM proves many things,

Indeed. Some even claim that energy, time and space have to be made of discrete minimal units because matter is.

 

[bilby]

Everything we wish to measure is compared to something of a known quantity. This is easy at scales with which we are familiar. A tape measure doesn't change the length of anything, in most cases. One might try to measure a spider web thread, but touching the thread distorts it, so we hold the tape very close and estimate the measurement. No imagine the thread is waving in the wind. We have to move the tape in the same pattern as the moving thread. The more precisely we want to measure(precise means smallest unit of measurement possible within the system), the greater the chance we distort the thread. In the end, whatever measurement we observe, there is a chance it's not as accurate(repeatable measurement of same quantity) as the numbers tell us.

That makes perfect sense to me. My confusion stemmed from the novel I referred to in my OP, written by an author who usually is highly rigorous in his suggestions about physics even when they are outlandish. It's disappointing that he took the woo route in his description of the observer/measurement effect in this latest book, it took me out of the experience in a small way upon reading that part (as I wasn't sure if it was just a misunderstanding of mine) and now a big way in retrospect, knowing that his portrayal was just nonsense. I know bilby is a fan of Cixin Liu, so I'd be curious to hear his views on the book, and that aspect in particular, if he's read it.

Sorry for the delay in responding - I was in the process of reading it when you PMed me, and I have deliberately been avoiding reading this thread until I finished in case of spoilers.

As I see it, Liu was employing the observer effect as a plot device - a way for the researchers to realize that they were being spied upon. When Ball Lightning is considered as a kind of prequel to Three Body, this makes a lot of sense from the narrative perspective. My first thought was that in such a 'noisy' environment, an uncollapsed waveform would be hugely implausible - but then, so is an electron the size of a soccer ball, or atomic nucleii that fuse at low temperatures and emit energy that effects very specific materials while leaving others unaffected. In short, it's science fiction, and the laws of physics can be whatever the author wants them to be. Liu has an excellent core of hard science in his work, but it necessarily takes a back seat to telling the story he wants to tell.

When a major thread of your novel is the exploration of quantum weirdness at macroscopic scales, it would be difficult and surprising to waste something as strange as the observer effect, by not having it too act rather differently and on a rather larger scale from its real world behaviour. I think it's excusable in this case, just as are the changes he makes to the other effects he appropriates. He isn't writing a textbook; He's speculating about how things would be if things were just a bit different. All SciFi does that - and IMO he does it better than most.

 

[Juma]

Its not about generic measurement interference (as in thermometer adds to the mass of what should be measured etc) Its about the problem of ”wave collapse”.
At quantum scale phenomena moves/distributed as waves but interacts as particles.
When you interacts some properties becomes fixed and others indeterminated.
A short example:
As if you measure magnetc spin of an electron you can only measure it in one direction: let call that direction the y-axis, it becomes indetermined at directions ortogonal to this (x and z axises).
So if you
1) measure along Y and only picks the particles a specific spin (up or down)
2) measure along X and picks the particles with spin right
3) then measures again along Y you will have an even distributuon of up and down

Similar behaviour can be shown with position an velocity.
If the position is measured the velocity to acertain degree becomes undetermined to a corresponding degree.


The problem with this ”wave collapse” is that it cannot be observed.

So one (more or less woo) theory is that the collapse of the wave is identical to what we experience with our mind.

It is position and momentum. The UP applies to any set of conjugate variables.

The wave function is a probability distribution. 'Collapsing' is metaphoric.

Flip a coin in the air. A wave function describes the probilities. When the coin hits the ground into a measurable state the wave function has collapsed into one of possible states.

10 light small balls are floating around in a column with airflow. There is a probability of a given state at any time, The act of measuring the state of the balls at any time selects the state. Measurement collapses the wave function.

No. There is no psi-function for flippin a coin. That is just macroscopic probability due to fact that we dont have enough knowledge about the forces in that specific system at that time.

The psi-wave is something else. Its an actual entity.

 

[steve_bank]

Its not about generic measurement interference (as in thermometer adds to the mass of what should be measured etc) Its about the problem of ”wave collapse”.
At quantum scale phenomena moves/distributed as waves but interacts as particles.
When you interacts some properties becomes fixed and others indeterminated.
A short example:
As if you measure magnetc spin of an electron you can only measure it in one direction: let call that direction the y-axis, it becomes indetermined at directions ortogonal to this (x and z axises).
So if you
1) measure along Y and only picks the particles a specific spin (up or down)
2) measure along X and picks the particles with spin right
3) then measures again along Y you will have an even distributuon of up and down

Similar behaviour can be shown with position an velocity.
If the position is measured the velocity to acertain degree becomes undetermined to a corresponding degree.


The problem with this ”wave collapse” is that it cannot be observed.

So one (more or less woo) theory is that the collapse of the wave is identical to what we experience with our mind.

It is position and momentum. The UP applies to any set of conjugate variables.

The wave function is a probability distribution. 'Collapsing' is metaphoric.

Flip a coin in the air. A wave function describes the probilities. When the coin hits the ground into a measurable state the wave function has collapsed into one of possible states.

10 light small balls are floating around in a column with airflow. There is a probability of a given state at any time, The act of measuring the state of the balls at any time selects the state. Measurement collapses the wave function.

No. There is no psi-function for flippin a coin. That is just macroscopic probability due to fact that we dont have enough knowledge about the forces in that specific system at that time.

The psi-wave is something else. Its an actual entity.

A wave function is a probability distribution. It describes behavior in a system. The coin is an example of what is meant by a wave function collapsing into a measurable state.

Nothing nautical or complicated. Using the words wave and collapse are loaded words conjuring up images, as with 'imaginary' numbers. Get past the jargon and underlying QM is basic math. It is the endless possibilities of interpretation that lead to confusion.

 

[Bomb#20]

Everything we wish to measure is compared to something of a known quantity. This is easy at scales with which we are familiar. A tape measure doesn't change the length of anything, in most cases. One might try to measure a spider web thread, but touching the thread distorts it, so we hold the tape very close and estimate the measurement. No imagine the thread is waving in the wind. We have to move the tape in the same pattern as the moving thread. The more precisely we want to measure(precise means smallest unit of measurement possible within the system), the greater the chance we distort the thread. In the end, whatever measurement we observe, there is a chance it's not as accurate(repeatable measurement of same quantity) as the numbers tell us.

That makes perfect sense to me. My confusion stemmed from the novel I referred to in my OP, written by an author who usually is highly rigorous in his suggestions about physics even when they are outlandish. It's disappointing that he took the woo route in his description of the observer/measurement effect in this latest book, it took me out of the experience in a small way upon reading that part (as I wasn't sure if it was just a misunderstanding of mine) and now a big way in retrospect, knowing that his portrayal was just nonsense. I know bilby is a fan of Cixin Liu, so I'd be curious to hear his views on the book, and that aspect in particular, if he's read it.

Sorry for the delay in responding - I was in the process of reading it when you PMed me, and I have deliberately been avoiding reading this thread until I finished in case of spoilers.

As I see it, Liu was employing the observer effect as a plot device - a way for the researchers to realize that they were being spied upon. When Ball Lightning is considered as a kind of prequel to Three Body, this makes a lot of sense from the narrative perspective. My first thought was that in such a 'noisy' environment, an uncollapsed waveform would be hugely implausible - but then, so is an electron the size of a soccer ball, or atomic nucleii that fuse at low temperatures and emit energy that effects very specific materials while leaving others unaffected. In short, it's science fiction, and the laws of physics can be whatever the author wants them to be. Liu has an excellent core of hard science in his work, but it necessarily takes a back seat to telling the story he wants to tell.

When a major thread of your novel is the exploration of quantum weirdness at macroscopic scales, it would be difficult and surprising to waste something as strange as the observer effect, by not having it too act rather differently and on a rather larger scale from its real world behaviour. I think it's excusable in this case, just as are the changes he makes to the other effects he appropriates. He isn't writing a textbook; He's speculating about how things would be if things were just a bit different. All SciFi does that - and IMO he does it better than most.

But saying it's "the observational apparatus itself that causes wave function collapse" isn't changing the effect or having it act a bit differently from its real world behavior. It matches the observed real world behavior to a T. That's why the infamous "it takes consciousness to collapse wave functions" interpretation of quantum mechanics is an interpretation, not a case of playing fast and loose with the science for the sake of the story, or for the sake of love of mysticism. A lot of hard-nosed first rate physicists have accepted that interpretation, most famously Eugene Wigner, who won a Nobel Prize. The consciousness interpretation is named after John von friggin' Neumann, although it's not clear whether he actually favored it or merely considered it an equally viable possibility. The physicists who accept that view do not do so because they're under the spell of new age woo peddlers. They do so because they feel pushed into it, much against their natural inclinations, by all the severe difficulties with all the alternative interpretations.

Of course it's shocking that something so prima facie ridiculous could come from serious science. But anybody who thinks that's all it takes to settle the matter should heed Niels Bohr's dictum: anybody who isn't shocked by quantum mechanics has not understood it. Not saying the consciousness hypothesis is right -- what do I know? Just saying people who treat the idea with the contempt it's getting in this thread are de facto claiming Wigner and von Neumann were idiots. They weren't idiots. They were smarter than all of us put together.

 

[steve_bank]

How can quantum physics be any more weird than anything else? People once thought radio waves passing through their house was weird, and scary.

 

[bigfield]

How can quantum physics be any more weird than anything else? People once thought radio waves passing through their house was weird, and scary.

Now we've gone the other way: I get annoyed because the house walls aren't completely radio-transparent and the Wi-Fi in the bedroom is rubbish.