Double Slit Experiment - radioactive particles

In summary, the conversation discusses the concept of measurement and its impact on the behavior of particles, particularly in relation to interference patterns. It is explained that the act of measurement forces a particle to make a decision, causing the wave function to collapse and resulting in a definitive outcome. The speaker also mentions that the presence of a measuring device can interfere with the results, and that this is a fundamental issue in understanding the measurement problem. The conversation also touches on the difference between radioactive particles and electrons, as well as the structure of measuring devices and their effects on the wave function.
  • #1
ProTerran
29
0
Hello,
Quick question:
Will radioactive particles give interference pattern if there is no measuring device?
 
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  • #2
By measuring device do you mean the screen the particles are projected on? How would you see the interference pattern if there is no measuring device?
 
  • #3
No, I mean the device, whose task is to determine through which slit the radioactive particle pass by.
The point is that in case of the radioactive particles measuring device can be passive, which means that measurement does not affect the measured object.
 
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  • #4
There is no such thing as a "passive" measurement device. So, if you can determine "which path" information there won't be an interference pattern.
 
  • #5
You mean that there is no a passive measurement devices, because an act of measurement collapses a wave function?
So, if there is a measuring device and information about a particle passing by slit isn't store anywhere, then will an interference pattern occur?
 
  • #6
He's trying to say that the very act of measurement collapses the wave function, so ANY measuring device would interfere with the results.
 
  • #7
Thanks for your reply.
I'm trying to make some sens out of this but it is pretty hard, because there is so many contradiction.
Let me ask you question in order to clarify issue regarding the measurement problem:
By saying "act of measurement" you mean:
1. the measurement device;
2. reviving an information.________
Sorry for my bad english
 
  • #8
Before I chip in, I should warn you that I'm not a proper physicist or anything, so I could very well be wrong. If I am I am sure someone will correct me though.

With regards to the measurement problem, the way I've made sense of it is that before a particle interacts in a given situation there are certain properties that you can't know exactly, such as position. Not just because it's too hard to measure them, but because the particle itself doesn't even have an exact position or whatever. In order to make a measurement you force the particle to make some sort of interaction, and so it has to make up its mind what it's doing. So it's not just because humans want to look at it, the particle has been forced to make a choice because of an interaction, and so the wave function for all of this fuzzy information has to collapse. Before the interaction, the particle has made no commitment about what is going to happen to it, so to speak. So any time a particle has to "make up its mind" the wave function collapses, and when you measure something, you force the particle to make up its mind. A particle will choose what information it has when it interacts, and a measurement device makes particles interact so that we can see this information. The measurements have been made whether we look at them or not, so storing the measurements without looking would be no different to making the measurements and looking - either way the particles in question have interacted with the measuring device. It's the interaction that collapses the wave function, not us looking at it.

Like I said, I'm pretty sure this is all right, but I am still very much on the learning curve myself, so anyone please correct me if I am wrong.
 
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  • #9
Thanks, it sounds ok to me, but still I am a little confused (btw, I'm not a physicist too).
At the beginning of this topic I have mentioned about the radioactive particles. What makes radioactive particles different from electrons? You don't need to send photons or other particles to get information about it's position because radioactive particle is already sending them.
What also bothers me in your description is why structure of the measuring device is so much different from the structure of the plate with slits that it collapses the wave function to one particular state? I guess that leads us again to the problem of measurement and what exactly it is.
 
  • #10
ProTerran said:
Hello,
Quick question:
Will radioactive particles give interference pattern if there is no measuring device?

It's quite simple, if we have made a measurement or we know which slit the particle/photon has gone through then we will have a 'wave pattern' ahead of us onto the screen.On the other hand add another slit and repeat the experiment,this time you'll notice the appearance of interference pattern,all due to the uncertainty of which slit it has gone through because we did not define a position to the wave function.The larger the particle is the less noticeable are the 'pattern/fringe differences'.

Regards,
ibysaiyan
 
  • #11
jbar18 said:
Before I chip in, I should warn you that I'm not a proper physicist or anything, so I could very well be wrong. If I am I am sure someone will correct me though.

With regards to the measurement problem, the way I've made sense of it is that before a particle interacts in a given situation there are certain properties that you can't know exactly, such as position. Not just because it's too hard to measure them, but because the particle itself doesn't even have an exact position or whatever. In order to make a measurement you force the particle to make some sort of interaction, and so it has to make up its mind what it's doing. So it's not just because humans want to look at it, the particle has been forced to make a choice because of an interaction, and so the wave function for all of this fuzzy information has to collapse. Before the interaction, the particle has made no commitment about what is going to happen to it, so to speak. So any time a particle has to "make up its mind" the wave function collapses, and when you measure something, you force the particle to make up its mind. A particle will choose what information it has when it interacts, and a measurement device makes particles interact so that we can see this information. The measurements have been made whether we look at them or not, so storing the measurements without looking would be no different to making the measurements and looking - either way the particles in question have interacted with the measuring device. It's the interaction that collapses the wave function, not us looking at it.

Like I said, I'm pretty sure this is all right, but I am still very much on the learning curve myself, so anyone please correct me if I am wrong.

Actually in QM the particles are said to have any of the probable outcome i.e are in any of the quantized state until the wave-function is collapsed,which is of course by measuring. (I maybe wrong)
 
  • #12
ProTerran said:
Thanks, it sounds ok to me, but still I am a little confused (btw, I'm not a physicist too).
At the beginning of this topic I have mentioned about the radioactive particles. What makes radioactive particles different from electrons? You don't need to send photons or other particles to get information about it's position because radioactive particle is already sending them.
What also bothers me in your description is why structure of the measuring device is so much different from the structure of the plate with slits that it collapses the wave function to one particular state? I guess that leads us again to the problem of measurement and what exactly it is.

Forget radioactive particles, they have nothing to do with the issue. Most quantum particles will exhibit interference through a suitable sized double slit. So let's use photons (particles of light) as an example.

Assume you send photons through a double slit apparatus with polarizering filters behind each of the slits. If the polarizers are aligned parallel, you DO get an interference pattern. If the polarizers are aligned anti-parallel (crossed), you do NOT get an interference pattern. When they are crossed, you have the ability to determine which slit so the pattern disappears.

If you consider this result, you will see that the presence of the polarizer itself does NOT cause the pattern to appear or not. It is the ability to obtain knowledge of the path by the relative orientation of the 2 polarizers. So I would say it is incorrect to say that the measurement apparatus disturbs the results, since it is the same apparatus either way.
 
  • #13
Well put Dr Chinese.

The perpendicular Vs parallel --> seems to suggest that interference pattern happens only between photons (or to be more accurate...between the Maxwell light wave) that are polarized in the same direction?

Maybe a perpendicular polarizer introduces some sort of phase difference?
 
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1. What is the Double Slit Experiment and why is it important?

The Double Slit Experiment is a classic physics experiment that demonstrates the wave-like behavior of particles. It involves a beam of particles, such as electrons or photons, being passed through two parallel slits and observed on a screen. The resulting pattern on the screen shows interference, indicating that the particles behave as waves. This experiment is important because it challenges our understanding of the fundamental nature of particles and has implications for quantum mechanics and the nature of reality.

2. How does the Double Slit Experiment work with radioactive particles?

The Double Slit Experiment can be performed with various types of particles, including radioactive ones. In this case, a radioactive source is placed in front of the two slits, and the particles emitted from the source are passed through the slits and observed on the screen. The resulting interference pattern shows that even radioactive particles exhibit wave-like behavior, further supporting the wave-particle duality concept in quantum mechanics.

3. What is the role of the observer in the Double Slit Experiment?

The role of the observer in the Double Slit Experiment is crucial. The act of observing or measuring the particles changes their behavior, causing them to lose their wave-like properties and behave as discrete particles. This is known as the collapse of the wave function. The observer's presence and interaction with the particles highlight the mysterious and complex nature of quantum mechanics.

4. Can the Double Slit Experiment be used to determine the exact path of a particle?

No, the Double Slit Experiment cannot determine the exact path of a particle. This is because the act of measuring or observing the particles changes their behavior, making it impossible to determine their exact path. This is also known as the uncertainty principle in quantum mechanics, which states that the more precisely we know a particle's position, the less we know about its momentum, and vice versa.

5. What are the real-world implications of the Double Slit Experiment?

The Double Slit Experiment has significant implications for our understanding of the nature of reality and has led to many technological advancements, such as the development of transistors and the understanding of quantum computing. It also challenges our classical view of the world and highlights the mysterious and complex nature of quantum mechanics. Further research and understanding of this experiment could potentially lead to revolutionary discoveries in various fields, including physics, technology, and philosophy.

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