Bell's Experiment Explained for 5th Graders

[MEMoirist]

Can someone please explain, using the language of a fifth-grader, what Bell's experiment looked like? I'd also appreciate links that put this information in lay-people's terms. Thanks.

 

[JesseM]

Check out [post=3237782]this post[/post] where I give a simple analogy for the type of reasoning Bell uses to show QM is incompatible with local realism, if you can follow that I can explain a little more about the type of physics experiments that this is meant to be analogous to.

 

[MEMoirist]

Thank you, but what I was hoping for was something more basic.

I see diagrams of a photon shooter sending twin photons in opposite directions. For ease of communication, let us say that the shooter sends them left and right.. When photons are twins (entangled by virtue of their originating pion), each spins in an opposite direction (let’s say up and down), so that their total spin always remains zero.

After the photons have traveled a few miles, you put some sort of spin detector in the path of one of the left twin. By determining the spin of the left particle, you automatically know the spin of the right twin and it will always spin in opposite directions. This much I understand.

But, I don’t understand what all of the excitement is about if that’s all there is to it. Do photons normally change their spin as they encounter friction or whatever? Is their natural spin east-west so that a north-south spin would be unnatural?

Now, it would be easy to get excited if there some sort of manipulation being applied to the left twin that is instantly matched by the right twin? If so, what manipulation is being applied and what is being matched? If I change the path of the left photon by using a mirror, does the right photon also change paths? Now THAT would be exciting!

Diagrams don’t show what happens beyond the filters.

Thanks.

 

[JesseM]

Thank you, but what I was hoping for was something more basic.

Did you try reading it through? The reasoning is actually pretty basic in that post, but if you have questions about any part of it I can explain.

I see diagrams of a photon shooter sending twin photons in opposite directions. For ease of communication, let us say that the shooter sends them left and right.. When photons are twins (entangled by virtue of their originating pion), each spins in an opposite direction (let’s say up and down), so that their total spin always remains zero.

After the photons have traveled a few miles, you put some sort of spin detector in the path of one of the left twin. By determining the spin of the left particle, you automatically know the spin of the right twin and it will always spin in opposite directions. This much I understand.

But, I don’t understand what all of the excitement is about if that’s all there is to it.

That's not all there is to it, if your read my analogy through you'll see why. The idea is that the experimenters have multiple detector settings (they can measure spin along different axes), and they choose randomly which one to use on each trial. On some trials they happen to choose the same setting and they always get identical (or opposite, depending on the type of particle and how it was prepared) results on these trials, but the "weird" part is the statistics they get on the trials where they chose different settings. In terms of my analogy, this is just like how Alice and Bob choose randomly which of the three boxes to scratch on their cards, and on any trial where they both choose the same box they always find the same fruit revealed when they scratch it. But if you just imagine that the two cards were printed with an identical set of hidden fruits behind all three boxes, some simple arithmetic shows that on the trials where they chose different boxes to scratch, you should expect that they'll see the same fruit at least 1/3 of the time; this is known as a type of "Bell inequality". It's violated in my imaginary scenario by the fact that they actually find the same fruit only 1/4 of the time when they scratch different boxes, and similarly in QM if you pick the right combination of three detector angles, you can get it so they have a 100% chance of same (or opposite) result when they pick the same angle, but only 25% chance of same (or opposite) result when they pick different angles.

 

[DrChinese]

Thank you, but what I was hoping for was something more basic.

I see diagrams of a photon shooter sending twin photons in opposite directions. For ease of communication, let us say that the shooter sends them left and right.. When photons are twins (entangled by virtue of their originating pion), each spins in an opposite direction (let’s say up and down), so that their total spin always remains zero.

After the photons have traveled a few miles, you put some sort of spin detector in the path of one of the left twin. By determining the spin of the left particle, you automatically know the spin of the right twin and it will always spin in opposite directions. This much I understand.

But, I don’t understand what all of the excitement is about if that’s all there is to it. ...

Now, it would be easy to get excited if there some sort of manipulation being applied to the left twin that is instantly matched by the right twin? If so, what manipulation is being applied and what is being matched? If I change the path of the left photon by using a mirror, does the right photon also change paths? Now THAT would be exciting!
...

The situation as you describe ("what all of the excitement is about...") was as it was in 1935 after EPR. It was a stalemate, no clear answer. Then Bell came along - there is more to it! He showed that the natural extension to EPR did not actually work. Since there is perfect matching (or anti-matching according to the setup) when the same angles are selected, the conclusion is that these must be effectively predetermined. That won't work for certain specific angle settings OTHER THAN matching angles. Recall that the QM prediction is cos^2(left-right) for light. When (left-right)=0, then the value is 100%. When it is 120 degrees, it is 25%.

So it turns out that the 25% value is inconsistent with predetermination. There are other values too. Even though the 100% value is consistent. So Bell's Theorem is that QM's predictions are NOT consistent with predetermination in all cases. That predetermination is often labeled "Local Realism". It consists of 2 assumptions, Locality and Realism.

 

[DrChinese]

P.S. What JesseM said... that explains in more detail. The key thing is that Local Realism requires assumptions OVER and ABOVE QM. Those assumptions lead to specific mathematical requirements that were overlooked for many years after EPR in 1935.

 

[MEMoirist]

Let’s start again.

I think you may be saying that to SEE what Bells experiment looked like, (my intended question) the first drawing would have a box (pion splitter) in the middle and a photon interrupter on the right and a photon interrupter on the left. (Because I’m an idiot with a serious case of dyslexia, I’m trying to create a visual for myself.)

Let’s start with these questions. Please answer them numbered so that I can understand where your answer meets my question. Try to go with “yes” and “no” or # for now. Once I have the basics down, the rest may make sense.

1) How many boxes with a pion splitter in the middle would I need to draw to show the possible pairings created by the left and right photon interrupters?

2) Can I view the interrupters as mirrors because I know what mirrors are and I’m not so certain what a polarizer is or does. Would that destroy the results?

3) Are you saying that there MUST be two photon interrupters for the experiment to be valid? Can the the right side simply take measurements while the left side manipulates the photon?

4) Are you saying that each interrupter MUST be actively trying to manipulate the photon (or not)?

5) Are you saying that photon interrupter on the left MUST operate independently from photon interrupter on the right?

6) Are you saying that photon interrupters may only redirect photons in one of three directions. UP, DOWN, or NOT AT ALL (Meaning that the mirror lays down so that there can be no manipulation)?

7) In Classical Physics, chances of each side choosing the same orientation are what?

8) In Quantum Mechanics, chances of each side choosing the same orientation are what?

9) Is #8 the right question?

If you could put your answers into shorter sentences and shorter paragraphs, it would be easier to understand. And if you could avoid mixing metaphors (cherries/lemons=+/-) it would be easier to visualize. Also, if you could take the time to use words rather than acronyms, it would be helpful. I’m only in fifth grade, remember. Terms like QM, EPR, cos/\2 left right for light are WAY beyond me, but I believe you can explain this to me without them. You’re so close. We’re even entangled

 

[JesseM]

Let’s start again.

I think you may be saying that to SEE what Bells experiment looked like, (my intended question) the first drawing would have a box (pion splitter) in the middle and a photon interrupter on the right and a photon interrupter on the left. (Because I’m an idiot with a serious case of dyslexia, I’m trying to create a visual for myself.)

There are many different types of Bell-style experiments, I'm not that familiar with the specifics of most so I haven't seen one with a "pion splitter" or a "photon interrupter", can you link to whatever you're talking about?

If you could put your answers into shorter sentences and shorter paragraphs, it would be easier to understand.

OK, but if I can make a request, if you have trouble understanding any sentence or idea could you please quote the ones that you don't understand and ask me to elaborate, rather than just asking me to start over from the beginning?

And if you could avoid mixing metaphors (cherries/lemons=+/-) it would be easier to visualize.

Why not start by trying to just visualizing the analogy on its own, without trying to understand for now how it connects to a Bell experiment? Just imagine the lotto cards sent to Alice and Bob at different locations, forget what they might stand for in terms of particles. It sounds like you're just shutting down without trying to follow it, because it isn't quite the sort of explanation you had in mind. But trust me, if you take the time to understand the analogy on its own, it really will make understanding the Bell experiment much easier.

Also, if you could take the time to use words rather than acronyms, it would be helpful. I’m only in fifth grade, remember. Terms like QM, EPR, cos/\2 left right for light are WAY beyond me, but I believe you can explain this to me without them. You’re so close. We’re even entangled

Sorry about that, I should have mentioned that "QM" is the common abbreviation for "Quantum mechanics". That's the only acronym I used, but of the others DrChinese mentioned, EPR stands for a thought-experiment about entanglement that Einstein, Podolsky and Rosen came up with. In that paper they were trying to argue for "hidden variables" to explain the correlations in quantum entanglement. What Bell did was to show that even a hidden variables theory can't explain these correlations, as long as you assume that the particles can't influence one another faster than light (by the way "FTL" is also a common acronym used for faster-than-light). It's not that important that you know about the EPR paper though, it's just part of the history. As for cos^2, that's just a mathematical term, it stands for the square of the cosine of an angle. This term appears in the equation for the probability both experimenters will get the same result when they set their detectors to different angles, but you don't really need to know the details to start with.

 

[DrChinese]

If you could put your answers into shorter sentences and shorter paragraphs, it would be easier to understand. And if you could avoid mixing metaphors (cherries/lemons=+/-) it would be easier to visualize. Also, if you could take the time to use words rather than acronyms, it would be helpful. I’m only in fifth grade, remember. Terms like QM, EPR, cos/\2 left right for light are WAY beyond me, but I believe you can explain this to me without them. You’re so close. We’re even entangled

First, welcome to PhysicsForums, MEMoirist! There are a lot of great members here who will try to answer your questions.

Second, I need to be honest that there is some background you will need to understand a Bell test in experimental terms. Without understanding this, it may not seem to prove anything. So if you will take some time to review some of the links we provide, even if they seem advanced, it will help. I know you are asking for a 5th grade explanation, but this will not really be possible.

Third, we hope you have arrived here with an open mind. If you choose to reject decades of theory and experiment, then there will be little we can do to assist. Regarding Bell, there are probably about 100 new scientific papers per month written on the subject. About half of these involve theory, and half are reports of experimental results. At this time, there are NO experimental reports which demonstrate anything at variance with the long established theory (back to about 1927) of Quantum Mechanics (QM).

I have written several web pages to help fill in background on the subject. I would recommend these 2 in particular:

Bell's Theorem with Easy Math:
http://drchinese.com/David/Bell_Theorem_Easy_Math.htm

Bell's Theorem: An Overview with Lotsa Links:
http://www.drchinese.com/Bells_Theorem.htm

 

[MEMoirist]

thanks for your help. I think I've got it. Here's my go at explaining.

First you need a photon shooter and two interceptor boxes. The interceptor boxes have three switch positions, A, B, and C. They also have two lights, Red and Green.

Line the boxes up end to end, set their switch positions to the same position, and shoot a single photon through them. Both lights will light up either red or green. The same colors will appear on each box 100% of the time. You never know in advance which color will appear, but you can predict with 100% certainty that both lights will be the same color.

Now randomly change the switches so that they are no longer always the same for both boxes. There is no longer a 100% certainty that the two colors will be the same.

Now take the same photon shooter and the same two interceptor boxes with the three switch positions, but this time you will also need a photon splitter. The splitter is a mirror that slices the photon in half, sending one half in one direction and the other half in another direction. You need to split photons in half so that they are both absolutely identical—perfect twins from the moment of their birth. (This eliminates he possibility of outside variables that scientists just don’t like when they look at experimental data.)

You need to place your interceptor boxes in the path of the photon trajectories. (In reality, the photons are sent through fiber optic cables so that the two interceptor boxes are miles away from one another, but I wanted to be able to visualize what is happening at its core level.) If you start shooting photons out of your shooter, and the switches on the two interceptors boxes are switched randomly to either A B or C, with neither box (or box’s operator) knowing what the other is doing, you should get matching colors on the two distant boxes 55% of the time.

When the experiment is run millions and millions of times, the actual result is 50% of the time. This is a mathematical and statistical impossibility. It is simply not possible to have this outcome--at least not in the world of particles.

So what happened?

The relationship between the twin photons caused the colors to agree 50% of the time, apparently to keep it in balance. If, instead of using the colors red and green, you were to use the numbers +1 and -1, with a 50% agreement, You would get “+1” 50% of the time and “–1” 50% of the time. This nets out to zero, which makes for some interesting curiosities to be considered about the world that we live in.

When the equipment was adjusted so that there was an almost imperceptible amount of time between the photons' arrival at the interceptor boxes and the switching of the interceptor box’s switches, the only way to arrive at a 50% agreement rate is for one photon to change its character to match its twin instantaneously, OR, one photon or something else had to change its instructions to the boxes, telling them how to light up, and they had to do this in zero time. OR, some part had to "have known" what would happen and compensate accordingly, which means that someone or some thing reached back in time, or that a common moment of now connects all particles, making the universe itself the local reality and all places within it non-local.

How did they decide which twin would change its instructions to the interceptor box? Did the interceptor boxes agree among themselves and adjust themselves accordingly? This seems to be the question, if my understanding is valid. There is at least one other-dimensional experience involving itself in the conversation and it appears to be aware, a condition that implies sentience.

If my understanding is correct, this relates to an article by Dr. Bern of Cornell that will be published this year. In a laboratory setting, he changed the order of what happens when you give a test, putting the practice after the test rather than before it. He shows that a certain type of student was able to reach through time and improve test scores by practicing after the test.

This new world makes SO much more sense than the last one!

 

[JesseM]

thanks for your help. I think I've got it. Here's my go at explaining.

First you need a photon shooter and two interceptor boxes. The interceptor boxes have three switch positions, A, B, and C. They also have two lights, Red and Green.

Line the boxes up end to end, set their switch positions to the same position, and shoot a single photon through them. Both lights will light up either red or green. The same colors will appear on each box 100% of the time. You never know in advance which color will appear, but you can predict with 100% certainty that both lights will be the same color.

Now randomly change the switches so that they are no longer always the same for both boxes. There is no longer a 100% certainty that the two colors will be the same.

Now take the same photon shooter and the same two interceptor boxes with the three switch positions, but this time you will also need a photon splitter. The splitter is a mirror that slices the photon in half, sending one half in one direction and the other half in another direction.

A mirror doesn't split a single photon into a pair of entangled photons, to do that you need something like spontaneous parametric down-conversion.

You need to place your interceptor boxes in the path of the photon trajectories. (In reality, the photons are sent through fiber optic cables so that the two interceptor boxes are miles away from one another, but I wanted to be able to visualize what is happening at its core level.) If you start shooting photons out of your shooter, and the switches on the two interceptors boxes are switched randomly to either A B or C, with neither box (or box’s operator) knowing what the other is doing, you should get matching colors on the two distant boxes 55% of the time.

Why 55%? I guess from your next comment you are talking about what would be predicted by a theory that obeyed local realism, not what is predicted by quantum physics. If so, probably you're talking about the local realist prediction that over the course of many trials, the frequency of getting the same color should be greater than or equal to 5/9, which is 55.555... %. But do you understand the reason for this prediction? This is really the most important part if you want to understand Bell's theorem. It has to do with the idea that, under local realism, we should expect that each photon just had an identical set of three predetermined responses to the three settings A,B,C. Again it's equivalent to the idea in my lotto card analogy that each card had an identical set of hidden fruits under each box (if you prefer, we could say that under each box is either a green patch or a red patch, to make the connection to the quantum experiment more clear).

When the experiment is run millions and millions of times, the actual result is 50% of the time.

Yeah, the idea is that you get a number smaller than the minimum predicted under local realism. It could be 50% or it could be something else, would depend on the exact details of the experiment. You didn't explain what's inside the "interceptor box" and I don't think there's any standard piece of lab equipment that goes by that name, I would imagine that inside the box is supposed to be something like a polarizer that has a certain chance of allowing the photon to pass through (so it goes towards a detector which causes the green light to come on) and a certain chance of reflecting the photon at some other angle (so it goes towards a different detector which causes the red light to come on). In that case, the probability that the two boxes will show the same color depends on the specific choice of angles for the polarizers in settings A, B, and C.

The relationship between the twin photons caused the colors to agree 50% of the time, apparently to keep it in balance.

No, nothing to do with keeping a balance, it could have been 53% or 37% depending on the angles of the polarizers in the three settings A, B, C. The only thing you really need to know is that in quantum physics it can be less than the local realist prediction of 5/9 = 55.555...%

When the equipment was adjusted so that there was an almost imperceptible amount of time between the photons' arrival at the interceptor boxes and the switching of the interceptor box’s switches, the only way to arrive at a 50% agreement rate is for one photon to change its character to match its twin instantaneously, OR, one photon or something else had to change its instructions to the boxes, telling them how to light up, and they had to do this in zero time. OR, some part had to "have known" what would happen and compensate accordingly, which means that someone or some thing reached back in time, or that a common moment of now connects all particles, making the universe itself the local reality and all places within it non-local.

Yes, all of these would be ways of explaining how the photons managed to create those strange statistics...although I don't quite understand that very last part where you say "a common moment of now connects all particles, making the universe itself the local reality". By the way there is one other solution you didn't mention, which is that it might be that when each photon reaches the detector, the detector (and the experimenter watching it) splits into multiple parallel versions, like parallel universes. In this case until there has been time for the two experimenters to communicate (using a signal moving at the speed of light or slower) it isn't necessary to decide which parallel copy of the left-hand experimenter is part of the same "universe" as which parallel copy of the right-hand experimenter. So in a way this scenario does allow you to preserve locality, at the expense of the belief that there is a unique reality about what happened with each measurement (so it could be said to violate the "realism" part of "local realism"). This is basically the type of solution preferred by those who advocate the many-worlds interpretation of quantum mechanics, you can read my post [post=1647627]here[/post] for some more info on how this interpretation is argued to preserve locality.

If my understanding is correct, this relates to an article by Dr. Bern of Cornell that will be published this year. In a laboratory setting, he changed the order of what happens when you give a test, putting the practice after the test rather than before it. He shows that a certain type of student was able to reach through time and improve test scores by practicing after the test.

There are a lot of claims to show psychic phenomena like this but they never seem to hold up under further scrutiny, and this isn't something that would be possible according to any mainstream interpretation of quantum mechanics.

 

[MEMoirist]

A mirror doesn't split a single photon into a pair of entangled photons, to do that you need something like spontaneous parametric down-conversion.

I tried beginning with pions (pi mesons) which is an already entangled pair of photons, but you didn’t know what I was talking about. If you didn’t know what I was talking about, then my classmates wouldn’t. That’s why I came up with an understandable way of splitting photons. I was trying to simplify to aid my getting to the point as opposed to obfuscate to make myself look smart. Does it really make that much difference if my classmates know that I have used “Spontaneous parametric down-conversion”, a non-linear cyrstal (neither of which they or I have ever heard of before) or a mirror? This is for a 5th grade science project, for *!#@’s sake! I’ll just change the name to “beam splitter”, but you could have said that at the outset and saved yourself a whole lot of words.

be greater than or equal to 5/9, which is 55.555... %.

OK, sorry about the missing decimal points. Perhaps my teacher would have nicked a few points of my grade for leaving them out. What would the experiment have to look like for you to arrive at a figure of 8/9 (which is 88.88888888888888888….%)

This is really the most important part if you want to understand Bell's theorem. It has to do with the idea that, under local realism, we should expect that each photon just had an identical set of three predetermined responses to the three settings A,B,C. Again it's equivalent to the idea in my lotto card analogy that each card had an identical set of hidden fruits under each box (if you prefer, we could say that under each box is either a green patch or a red patch, to make the connection to the quantum experiment more clear).

You tell me that I don’t yet understand Bell’s theorem, but you fail to explain what I am missing. You can talk about those lotto cards as many times as you want but I still don’t get it. Do you know what you are saying?

Yeah, the idea is that you get a number smaller than the minimum predicted under local realism. It could be 50% or it could be something else

How would you design an experiment to produce a result of your suggested 37%? How would you design it to produce a result of 22%? Remember, my first question did not ask for the math. It asked for the experiment in the language of a 5th grader. And if you MUST use your stupid lotto cards, would you please use shorter sentences and smaller words so that I can turn your words into drawings? I may be smart but I have dyslexia. I have to take your words, cut and paste them into a word processor, enlarge the type, and then reconstruct your sentences and paragraphs, all the while looking up words that I don’t understand. Then, when I can do that, I often find that you don’t make your point. It is has become easier to look elsewhere for answers. I hope that you aren’t a teacher.

This is basically the type of solution preferred by those who advocate the many-worlds interpretation of quantum mechanics, you can read my post here for some more info on how this interpretation is argued to preserve locality.

I am quite familiar with the idea of multi-dimensional realities, and the metaverse. I know how locality can be preserved as an aspect of non-locality. I didn’t understand the post you pointed me to though. Too bad that you think of me as dumb just because I don't know things that you know. I promise you that I know things that you don't know. Does that make you dumb?

There are a lot of claims to show psychic phenomena like this but they never seem to hold up under further scrutiny, and this isn't something that would be possible according to any mainstream interpretation of quantum mechanics.

If you don’t understand how Dr. Bern’s research relates to any mainstream interpretation of Quantum Mechanics, then you don’t understand how this relates to the Bell Theorum and you don’t understand how it relates to the two-slit experiment where the wave pattern collapses when it is being observed. If you don’t know these things, do you really know this topic as well as you are trying to convice me that you do? Do you know what a multi-dimensional reality looks like? If you can’t use simple words and ideas, is it because you don’t really know what you are talking about. You state your hypothesis with such certainty but you offer no proof, nor do you give me any reason to question my suggestions.

Jesse, I’m not expecting to win the Nobel Prize for my science project. I’d be happy enough to win the science fair.

I’ll look someplace else for help.

 

[DrChinese]

... When the equipment was adjusted so that there was an almost imperceptible amount of time between the photons' arrival at the interceptor boxes and the switching of the interceptor box’s switches, the only way to arrive at a 50% agreement rate is for one photon to change its character to match its twin instantaneously, OR, one photon or something else had to change its instructions to the boxes, telling them how to light up, and they had to do this in zero time. OR, some part had to "have known" what would happen and compensate accordingly, which means that someone or some thing reached back in time, or that a common moment of now connects all particles, making the universe itself the local reality and all places within it non-local.
...

Pretty good up to this point, I think you have learned a lot!

The stuff about the upcoming article makes no sense. In fact a message from the future arrived to assure me that wouldn't happen.

The point you are supposed to be at is: either the universe is non-local, or the future affects the past, or quantum objects do not have properties independent of observation, or similar. In other words, at least one of the local realistic assumptions is incorrect.

 

[DrChinese]

...Too bad that you think of me as dumb just because I don't know things that you know. I promise you that I know things that you don't know. Does that make you dumb?

If you don’t understand how Dr. Bern’s research relates to any mainstream interpretation of Quantum Mechanics, then you don’t understand how this relates to the Bell Theorum and you don’t understand how it relates to the two-slit experiment where the wave pattern collapses when it is being observed. If you don’t know these things, do you really know this topic as well as you are trying to convice me that you do? Do you know what a multi-dimensional reality looks like? If you can’t use simple words and ideas, is it because you don’t really know what you are talking about. You state your hypothesis with such certainty but you offer no proof, nor do you give me any reason to question my suggestions.

Jesse, I’m not expecting to win the Nobel Prize for my science project. I’d be happy enough to win the science fair.

I’ll look someplace else for help.

Completely inappropriate commentary. JesseM spent time trying to assist you. I'm not sure what's going on, but something is quite fishy here.

 

[JesseM]

I tried beginning with pions (pi mesons) which is an already entangled pair of photons but you didn’t know what I was talking about.

Actually, pi mesons are a different type of particle from photons.

If you didn’t know what I was talking about, then my classmates wouldn’t. That’s why I came up with an understandable way of splitting photons. I was trying to simplify to aid my getting to the point as opposed to obfuscate to make myself look smart. Does it really make that much difference if my classmates know that I have used “Spontaneous parametric down-conversion”, a non-linear cyrstal (neither of which they or I have ever heard of before) or a mirror? This is for a 5th grade science project, for *!#@’s sake! I’ll just change the name to “beam splitter”, but you could have said that at the outset and saved yourself a whole lot of words.

You're getting awfully defensive, I wasn't trying to criticize you or tell you what you could or couldn't do in a science project, I was just pointing out that this part wasn't accurate because I thought you might like to know. Aren't you posting here because you want feedback on whether what you say is right or not? If you want it to be simple but don't want it to be inaccurate, you could just say something like "there's a kind of crystal that can split one photon into two identical photons".

OK, sorry about the missing decimal points. Perhaps my teacher would have nicked a few points of my grade for leaving them out. What would the experiment have to look like for you to arrive at a figure of 8/9 (which is 88.88888888888888888….%)

Again I wasn't criticizing, I genuinely wasn't sure why you said 55%. Then it occurred to me that maybe you were talking about one particular way of stating a Bell inequality, in which the probability of getting the same result over all trials is greater than or equal to 5/9. I was more used to seeing it stated in terms of the probability for getting the same result on only those trials where they picked different settings (leaving aside the trials where they picked the same settings, where there's a 100% chance of same result). In that case the probability is greater than or equal to 1/3, so that's the number I was more used to seeing. Again not a criticism or saying you should do it different, just explaining why I wasn't sure initially where you had gotten that number, and double-checking to make sure my guess about where you got it was right.

You tell me that I don’t yet understand Bell’s theorem

I didn't really say that, I just asked if you understood how they arrived at the 55% figure, and said that this is "the most important part if you want to understand Bell's theorem". If you did understand you could just say "yes, I already understand where that number comes from".

but you fail to explain what I am missing.

I did try to explain it, I said "It has to do with the idea that, under local realism, we should expect that each photon just had an identical set of three predetermined responses to the three settings A,B,C." If you have trouble understanding what I mean by "predetermined responses", then just ask (it has to do with the idea that there are "hidden variables" that determine how the photon will behave...again it's easier to understand with an analogy, like the hidden fruits behind the three boxes of the lotto card)

You can talk about those lotto cards as many times as you want but I still don’t get it.

I can't help you to "get it" if you don't tell me specifically what you don't get about it, that's why I asked before "if I can make a request, if you have trouble understanding any sentence or idea could you please quote the ones that you don't understand and ask me to elaborate, rather than just asking me to start over from the beginning?" If you want to try to understand, then just read through and copy and paste the first sentence you can't follow in the explanation, then I'll explain in more detail and we can continue from there. But if the issue is that you just don't want to put the effort to try to follow it, then I can't help you.

But look, maybe if you just care about what you need for the presentation, then it's not important to you to understand where the 55% comes from. You could just say something like this:

"Imagine the photon moving to the left reaches the interceptor box on the left, which is on setting A. Now, what is it that determines whether the green light or the red light comes on? We might imagine that it just has to do with the properties of that one photon, and has nothing to do with what's going on with the other photon and the other box. But physicists can show that if that were true, then the probability both boxes would light up the same color must be greater than or equal to 55%."

In this case you aren't claiming to know why the assumption (it just has to do with the properties of that one photon, and has nothing to do with what's going on with the other photon and the other box) leads to the conclusion (the probability both boxes would light up the same color must be greater than or equal to 55%), you're just stating it as a fact. If you think that's all that's needed then go for it! Again I don't want to say anything about what you should or shouldn't do for a presentation, that's your call. I'm just saying that if you want to understand Bell's theorem, I don't think you can really understand it without having a general idea of why that assumption leads to that conclusion.

How would you design an experiment to produce a result of your suggested 37%? How would you design it to produce a result of 22%?

Same way you'd get it to produce the result of 50%, by picking the right combination of angles for the polarizers in settings A, B, C. I don't actually know what the minimum possible fraction is since I haven't checked the math on that, but certainly it would be possible in quantum physics to get results larger than 50% but still smaller than 55%.

Remember, my first question did not ask for the math. It asked for the experiment in the language of a 5th grader.

Then you can just say something like "in quantum physics it's possible to design an experiment where you get the same result less than 55% of the time, for example it might be 50%." That way you don't have to go into details, or suggest that 50% is the unique correct answer in quantum physics.

And if you MUST use your stupid lotto cards, would you please use shorter sentences and smaller words so that I can turn your words into drawings? I may be smart but I have dyslexia.

OK, if I rewrite the whole thing with shorter sentences, will you promise to actually look through it carefully and tell me the first sentence you don't understand, like I asked? I don't want to rewrite the whole thing and just have you give another general dismissive reaction.

If you want to "turn my words into drawings", would it help if I just posted some drawings? I'm more of a visual thinker than a verbal one myself, maybe that's why my sentences aren't always as clear as they could be. But communication is a lot easier if you ask for further explanation in a nice way, rather then getting angry and making disparaging comments about what I said.

Anyway it may be that you aren't that interested in knowing the reasoning behind the 55% if it isn't necessary for your presentation. If that's the case, no problem, I just offered up the lotto card thing because you asked for help in understanding Bell's theorem.

I didn’t understand the post you pointed me to though. Too bad that you think of me as dumb just because I don't know things that you know. I promise you that I know things that you don't know. Does that make you dumb?

Again you're being really defensive, I never suggested I thought you were dumb, and if you are in 5th grade your writing is more advanced than most that age (I didn't realize you were saying you were literally a 5th grader before, maybe in part because your writing seemed too sophisticated, I thought you were just asking us to imagine you as a 5th grader as a way of making sure we kept our explanations simple). The post I linked to was mostly just meant to give references to physics papers in case you didn't trust what I was saying about the many worlds-interpretation. If you're looking for more of a conceptual explanation for how the many-worlds interpretation explains these results, I can go into that too once we've cleared up the lotto card analogy. But again, only if you're interested.

If you don’t understand how Dr. Bern’s research relates to any mainstream interpretation of Quantum Mechanics, then you don’t understand how this relates to the Bell Theorum and you don’t understand how it relates to the two-slit experiment where the wave pattern collapses when it is being observed.

Actually it's a common confusion that human consciousness is relevant to the two-slit experiment (don't feel bad because many articles about it give this impression). Even if you just had a machine making measurements at the slits, and no human ever looked at what the machine had recorded, this would still destroy the wave pattern on the screen behind the slits. In fact if you're sending a particle with electric charge through the slits, like an electron, then you have to do it in a vacuum because if the electron interacts with air molecules as it travels, even that works the same way as an "observation" and destroys the wave pattern on the screen.

Anyway, trust me that Dr. Bern's claims are something something very few physicists would take seriously at all, the idea of humans being able to affect particles just by thinking is seen by almost all physicists as fringe science.

 

[DrChinese]

This is for a 5th grade science project, for *!#@’s sake! ...

And you are a 5th grader. Riiiiiiiiiiiiiiiiiiiiight.

By the way, this is the wrong place for homework help. Try:

https://www.physicsforums.com/forumdisplay.php?f=152

 

[DrChinese]

JesseM,

Article:

http://www.dbem.ws/FeelingFuture.pdf

And the refutation:

http://www.ruudwetzels.com/articles/Wagenmakersetal_subm.pdf

Both being published in the Journal of Personality and Social Psychology, I believe. Sad when the APA (that's the American Psychological Association) ventures into physics and apparently, doesn't know it might need a bit of help in the matter. And embarrassing, I'm sure, to a few over at the APA.