Does a Sensor interact with atoms in the double slit experiment?

[user079622]

1. Patterns changes depend sensor is on or off, so sensor must somehow interact with atoms?

2. What is sensor, how he works/detect atoms?

3. If sensor is plugged but human dont monitor his results, what is pattern of atoms?

 

[DrClaude]

1. Patterns changes depend sensor is on or off, so sensor must somehow interact with atoms?

2. What is sensor, how he works/detect atoms?

3. If sensor is plugged but human dont monitor his results, what is pattern of atoms?

1. Yes.
2. The details are not important. But for example, it could be a laser shining light on the atom, with a light detector on the other side to monitor its intensity.
3. Pattern is not affected by humans. In the example in 2, you could even remove the light detector and just have the laser. That would be enough to affect the pattern.

 

[PeroK]

1. Patterns changes depend sensor is on or off, so sensor must somehow interact with atoms?

2. What is sensor, how he works/detect atoms?

3. If sensor is plugged but human dont monitor his results, what is pattern of atoms?

Note that the lecture is significantly wrong. It says that if you have a single slit, then the particles act like particles and do not diffract. But, if you have two slits, then the particles act like waves, diffract and create an interference pattern.

I emailed Al-Khalili about it but I didn't get a response.

 

[user079622]

1. Yes.
2. The details are not important. But for example, it could be a laser shining light on the atom, with a light detector on the other side to monitor its intensity.
3. Pattern is not affected by humans. In the example in 2, you could even remove the light detector and just have the laser. That would be enough to affect the pattern.

If that is case, so there is not mystery here, sensor affect atom, not human consciousness.
Everything is logic.

 

[user079622]

Note that the lecture is significantly wrong. It says that if you have a single slit, then the particles act like particles and do not diffract. But, if you have two slits, then the particles act like waves, diffract and create an interference pattern.

I emailed Al-Khalili about it but I didn't get a response.

Do you agree with text below?

"An electron is never in two places at the same time. That's just an unfortunate mental model that has established itself in the public's imagination about quantum mechanics. In reality superposition is a mathematical property of the theory. It is not a physical property of quantum systems. "

 

[PeroK]

Do you agree with text below?

"An electron is never in two places at the same time. That's just an unfortunate mental model that has established itself in the public's imagination about quantum mechanics.

In reality superposition is a mathematical property of the theory. It is not a physical property of quantum systems. "

I agree with the first part. Not the second. Superposition is a key property of quantum systems.

A particle in QM is described by a state; not by its position. A particle can physically be in a superposition of two states.

The trick, which even the writers of popular science fail to master, is to stop thinking about a particle's position as the characteristic that determines and describes its existence.

 

[user079622]

I agree with the first part. Not the second. Superposition is a key property of quantum systems.

A particle in QM is described by a state; not by its position. A particle can physically be in a superposition of two states.

The trick, which even the writers of popular science fail to master, is to stop thinking about a particle's position as the characteristic that determines and describes its existence.

If sensor affect atom/electron than no mystery here..
In lots of text/videos they say that human consciousness change results.
Physics is not magic, everything is deterministic but problem we dont understand how it works

 

[DrClaude]

In lots of text/videos they say that human consciousness change results.

Not serious sources.

Physics is not magic, everything is deterministic but problem we dont understand how it works

No, as far as we can tell (i.e., quantum mechanics is a correct description of Nature), Nature is not deterministic, but inherently random.

 

[Nugatory]

In lots of text/videos they say that human consciousness change results.

And stuff like that is why we have the forum rules about acceptable sources; textbooks and peer-reviewed publication.

 

[pines-demon]

No, as far as we can tell (i.e., quantum mechanics is a correct description of Nature), Nature is not deterministic, but inherently random.

This is true (unless we take an interpretation different from Copenhagen interpretation)

 

[DrClaude]

This is true (unless we take an interpretation different from Copenhagen interpretation)

You prepare a spin-1/2 system to point along +z. You measure spin along x. In which interpretation(s) is the result of that measurement deterministic?

 

[pines-demon]

You prepare a spin-1/2 system to point along +z. You measure spin along x. In which interpretation(s) is the result of that measurement deterministic?

Plenty. You have Bohmian or superdeterminism for example. Even many-worlds tells you what happens deterministically but in a weird way.

 

[user079622]

Not serious sources.


No, as far as we can tell (i.e., quantum mechanics is a correct description of Nature), Nature is not deterministic, but inherently random.

When you say Nature, you mean microworld?
So microworld(particles) is inherently random and macroworld(fluids, planets, falling stones,projectiles etc) are deterministic?

@PeroK

Is something random just because humans don't know how to describe how something actually works?

 

[PeroK]

So microworld(particles) is inherently random and macroworld(fluids, planets, falling stones,projectiles etc) are deterministic?

The macroscopic world is highly unpredictable. Only simple systems like planetary motion are generally predictable. Some people claim that if you knew everything, then you could predict everything, but I don't see that at all. If I tell you that tomorrow after breakfast I'm going to toss a coin, then how do you go about predicting heads or tails? Where's the determinism there? People who claim coin tosses are deterministic always want to wait until the coin is in the air (!) before they can calculate the result. You might as well wait until it has landed and then just look to see.

There's no process you can even begin to describe what would lead you from my current state as a complex biological machine to the conclusion about precisely where, when and how I'll toss a coin tomorrow. I might even change my mind and wait until the next day - or not do it at all.

There's a well-established area of mathematical physics generally called chaos, which quantifies the level of unpredictability in systems, especially regarding sensitivity to initial conditions. This includes things like fluid turbulence, stock markets, human and animal behaviour and weather systems. Chaos can be shown to emerge from the simplest non-linear mathematical systems.

In many ways the inherent randonmess at the microscopic level is irrelevant to the unpredictability in complex, dynamic, macroscopic systems.

If you think you see determinism everywhere in nature, then you ought perhaps to take a closer look.

 

[user079622]

The macroscopic world is highly unpredictable. Only simple systems like planetary motion are generally predictable. Some people claim that if you knew everything, then you could predict everything, but I don't see that at all. If I tell you that tomorrow after breakfast I'm going to toss a coin, then how do you go about predicting heads or tails? Where's the determinism there? People who claim coin tosses are deterministic always want to wait until the coin is in the air (!) before they can calculate the result. You might as well wait until it has landed and then just look to see.

There's no process you can even begin to describe what would lead you from my current state as a complex biological machine to the conclusion about precisely where, when and how I'll toss a coin tomorrow. I might even change my mind and wait until the next day - or not do it at all.

There's a well-established area of mathematical physics generally called chaos, which quantifies the level of unpredictability in systems, especially regarding sensitivity to initial conditions. This includes things like fluid turbulence, stock markets, human and animal behaviour and weather systems. Chaos can be shown to emerge from the simplest non-linear mathematical systems.

In many ways the inherent randonmess at the microscopic level is irrelevant to the unpredictability in complex, dynamic, macroscopic systems.

If you think you see determinism everywhere in nature, then you ought perhaps to take a closer look.

" I might even change my mind and wait until the next day - or not do it at all."

The mind is determined to will this or that by a cause which is also determined by another, and this again by another, and so to infinity.
Man can do what he wants, but he cannot will what he wills.


But you dont know 100% initials conditions when you throw a coin.
And only because you will never know all initials condition with 100% accuracy, doesnt mean it is random.

 

[PeroK]

The mind is determined to will this or that by a cause which is also determined by another, and this again by another, and so to infinity.
Man can do what he wants, but he cannot will what he wills.

This is a science forum. You might try finding a new age mysticism forum for stuff like that!

 

[Nugatory]

Is something random just because humans don't know how to describe how something actually works?

The word “random” is used in two different ways, and it is important not to confuse them.

One is the randomness of a tossed coin: if we knew the state exactly, we could in principle use Newton’s deterministic laws to calculate the exact trajectory of the coin and hence whether it lands heads or tails. The physics is deterministic and the randomness comes from the unknown initial conditions.
The second is the randomness of many (@pines-demon has mentioned Bohmian mechanics and superdeterminism as exceptions) quantum mechanical interpretations: the randomness comes from the wave function only giving us probabilities of collapse to various outcomes. Because the wave function completely specifies the state there is no escaping the randomness.

There is of course the possibility that you mention: that there is some underlying “how it works” mechanism that we don’t know about. If we had such a theory, then the apparent randomness of quantum mechanics would be of the tossed-coin type. However…. In the absence of such a theory, this is just idle speculation…. Generations of physicists have spent the last century trying and failing to find such a theory, and generally the better they understand the problem the greater their skepticism that such a theory might exist… and finally the observed violations of Bell’s inequality show that any such theory must be at least as weird as quantum mechanics and will be inconsistent with our classical intuition of cause and effect.

 

[berkeman]

And with that helpful post by @Nugatory this thread is now closed. (and the OP is on a temporary vacation from PF)