Paul WV

Beckley, WV

#303 Mar 18, 2012
polymath257 wrote:
<quoted text>
Is a water wave a 'real, material object'? A water wave will interfer with itself if it goes through two openings in a barrier and won't do so if there is a barrier between the openings. The electron probability wave is just as 'real' and 'material' as a water wave. But the same types of interference patterns can be seen for water waves as for probability waves (although on much different scales).
As far as I can tell, you are getting confused by terms like 'real' and 'material' that are rather vague. This is probably due to your philosophical position and provides a good example of how philosophical assumptions lead to confusion. Unless there are *very* precise definitions of these (and many other ) concepts, you will find yourself running around in circles as philosophers tend to do.
Most phycists tend not to use the word 'material' any longer, except when applied to macroscopic phenomena--far above the level of subatomic particles. It is a word that tends to confuse rather than clarify.
Though you think science has settle the question, it is not settled as demonstrated by this article from 2011:

" http://www.nature.com/news/quantum-theorem-sh... ;

You have not yet provided any links backing your postion.
Paul WV

Beckley, WV

#304 Mar 18, 2012
polymath257 wrote:
<quoted text>
Is a water wave a 'real, material object'? A water wave will interfer with itself if it goes through two openings in a barrier and won't do so if there is a barrier between the openings. The electron probability wave is just as 'real' and 'material' as a water wave. But the same types of interference patterns can be seen for water waves as for probability waves (although on much different scales).
As far as I can tell, you are getting confused by terms like 'real' and 'material' that are rather vague. This is probably due to your philosophical position and provides a good example of how philosophical assumptions lead to confusion. Unless there are *very* precise definitions of these (and many other ) concepts, you will find yourself running around in circles as philosophers tend to do.
Most phycists tend not to use the word 'material' any longer, except when applied to macroscopic phenomena--far above the level of subatomic particles. It is a word that tends to confuse rather than clarify.
We are arguing like some Greek philospohers did over how many teeth does a horse have, when one wise man said: "Let's count them." Has the experiment I suggested been performed?

“Think&Care”

Since: Oct 07

Location hidden

#305 Mar 18, 2012
Paul WV wrote:
<quoted text>
Though you think science has settle the question, it is not settled as demonstrated by this article from 2011:
" http://www.nature.com/news/quantum-theorem-sh... ;
You have not yet provided any links backing your postion.
I just read the relevant scientific article on arxiv for this. Funny, it seems to be saying exactly what I've been saying: that the wave function is a physical property of the system. It says any attept to *merely* see it as statistical rather than physical is contradictory to QM. Again, that is what I have been saying.

Once again, the wave function describes the probabilities of detecting electrons (or other quantum particles) and is as real as any other wave. This article does not contradict this statement in any way.

“Think&Care”

Since: Oct 07

Location hidden

#306 Mar 18, 2012
Paul WV wrote:
<quoted text>
We are arguing like some Greek philospohers did over how many teeth does a horse have, when one wise man said: "Let's count them." Has the experiment I suggested been performed?
The biggest issue with your, exact, experiment is making the appropriate barrier. To have an interference pattern requires the slits to be *very* close together. Any material to make your barrier between the slits would have to be at least that thin. Every material that is that thin is transparent to light (or electrons), so the requirements that it be a 'barrier' in the sense of not allowing electrons or light to pass across is impossible to create. Because of this, there would be an interference pattern.

Unless you have an idea of how to get around this issue, there is no way to do exactly what you asked.

Now, what we *can* do is have a variety of ways of attempting to detect which slit the photon or electron goes through. Such experiments have been done and they consistently destory the interference effect.

“Think&Care”

Since: Oct 07

Location hidden

#307 Mar 18, 2012
The arxiv article was actually very interesting. Here are a couple of quotes:

"
It may be useful to summarize the assumptions that
are necessary for the result. Three can be identified. The
first is that if a quantum system is prepared in isolation
from the rest of the universe, such that quantum the-
ory assigns a pure state, then after preparation the sys-
tem has a well defined set of physical properties. This
assumption is necessary for the question we address to
make sense: if such physical properties donít exist, it
is meaningless to ask whether or not the quantum state
is among them. Note that while there are well-known
obstacles to identifying physical properties of individual
systems when they are entangled with other systems,
these problems do not arise here, since each system is
in a pure state.
The second assumption is that it is possible to prepare
multiple systems such that their physical properties are
uncorrelated. Experimentalists aim to achieve this either
by building and operating different copies of the same ex-
perimental apparatus, or by reusing the same apparatus
after a sufficient time period has elapsed that they are
confident the later run is independent of the earlier.
The third assumption is that measuring devices re-
spond solely to the physical properties of the systems
they measure. We do not assume underlying determin-
ism. Even given a full specification of &#955;, it may only
be possible to make probabilistic predictions about the
outcome of a measurement."

I'll point out that a 'physical property' may only give probabilistic information in this article. The conclusion they reach is that the quantum state of a system (the wave function) is such a physical property.

"In some versions of quantum theory, on the other hand,
there is no collapse of the quantum state. In this case, af-
ter a measurement takes place, the joint quantum state of
the system and measuring apparatus will contain a com-
ponent corresponding to each possible macroscopic mea-
surement outcome. This is unproblematic if the quantum
state merely reflects a lack of information about which
outcome occurred. But if the quantum state is a phys-
ical property of the system and apparatus, it is hard to
avoid the conclusion that each marcoscopically different
component has a direct counterpart in reality."

In other words, based on the assumptions above, a multiple-worlds viewpoint, similar to that of Everett's, is strongly supported by this reasoning.
Paul WV

Beckley, WV

#308 Mar 18, 2012
polymath257 wrote:
<quoted text>
I just read the relevant scientific article on arxiv for this. Funny, it seems to be saying exactly what I've been saying: that the wave function is a physical property of the system. It says any attept to *merely* see it as statistical rather than physical is contradictory to QM. Again, that is what I have been saying.
Once again, the wave function describes the probabilities of detecting electrons (or other quantum particles) and is as real as any other wave. This article does not contradict this statement in any way.
This Theorem has just been proposed in November 2011, but you say it's nothing more than what you've been posting here?

“Quantum Junctn: Use Both Lanes”

Since: Dec 06

Tulsa, Oklahoma USofA

#309 Mar 18, 2012
Paul WV wrote:
<quoted text>
Then again, an atheist is lost.
Then again, you Genuine Catholicsô are guilty of participating in a systematic child-rape ring.

“Think&Care”

Since: Oct 07

Location hidden

#310 Mar 18, 2012
Paul WV wrote:
<quoted text>
This Theorem has just been proposed in November 2011, but you say it's nothing more than what you've been posting here?
It is *supporting* what I have been posting here, yes. The argument made in the article is yet another nail in the coffin of classical intuition. I did not previously know this argument and it is quite interesting, but the conclusion is *far* from being surprising except to those who want to think of electrons as little balls flying through space and quantum states as simply 'mathematical abstractions'. Just like Bell's theorem, it shows the difficulties when we attempt to hold to outmoded ideas like that the wave function is not real, yet only gives probabilities of detection.
Paul WV

Beckley, WV

#311 Mar 18, 2012
polymath257 wrote:
<quoted text>
It is *supporting* what I have been posting here, yes. The argument made in the article is yet another nail in the coffin of classical intuition. I did not previously know this argument and it is quite interesting, but the conclusion is *far* from being surprising except to those who want to think of electrons as little balls flying through space and quantum states as simply 'mathematical abstractions'. Just like Bell's theorem, it shows the difficulties when we attempt to hold to outmoded ideas like that the wave function is not real, yet only gives probabilities of detection.
So if a wavefunction for an electron goes into two boxes, as going through two slits of the two slit experiment, in which box is the electron to be found?

“Think&Care”

Since: Oct 07

Location hidden

#312 Mar 18, 2012
Paul WV wrote:
<quoted text>
So if a wavefunction for an electron goes into two boxes, as going through two slits of the two slit experiment, in which box is the electron to be found?
There is no way to tell. The most you can know is the *probability* of detecting the electron in each box. Assuming everything is symmetrical, there would be a 50/50 chance of detecting an electron in each box. This is what it means to be a *probability wave*.

“Think&Care”

Since: Oct 07

Location hidden

#313 Mar 18, 2012
Paul WV wrote:
<quoted text>
So if a wavefunction for an electron goes into two boxes, as going through two slits of the two slit experiment, in which box is the electron to be found?
Just a follow-up to this.

Suppose we set up this experiment, with everything being symmetrical, so the probability of detecting an electron is 50/50 for each box.

Now, we put the intensity of our electron beam so low that only one electron goes through at a time.

One electron goes through. There is NO WAY to tell ahead of time which box it will appear in.

Second electron goes through. There is NO WAY to tell ahead of time which box it will appear in.

Third electron goes through. There is NO WAY to tell ahead of time which box the electron will appear in.

However, as we send more and more electrons through the device and into the boxes, about 50% will appear in one box and 50% in the other.

Make sense yet?

“Think&Care”

Since: Oct 07

Location hidden

#314 Mar 18, 2012
Paul WV wrote:
<quoted text>
So if a wavefunction for an electron goes into two boxes, as going through two slits of the two slit experiment, in which box is the electron to be found?
Now, suppose we have an asymmetrical arrangement where the probability wave is such that the box on the left has a 30% chance of having an electron appear in it and the box on the right has a 70% chance.

Again, we turn the intensity of the beam down so low that only one electron goes through at a time.

First electron goes through. There is NO WAY ahead of time to tell which box it will appear in.

Second electron goes through. There is NO WAY ahead of time to tell which box it will appear in.

Etc.

But, as we send more and more electrons through the device, we will find about 30% show up in the left box and 70% show up in the right box.

“Think&Care”

Since: Oct 07

Location hidden

#315 Mar 18, 2012
Paul WV

Beckley, WV

#316 Mar 18, 2012
polymath257 wrote:
<quoted text>
Now, suppose we have an asymmetrical arrangement where the probability wave is such that the box on the left has a 30% chance of having an electron appear in it and the box on the right has a 70% chance.
Again, we turn the intensity of the beam down so low that only one electron goes through at a time.
First electron goes through. There is NO WAY ahead of time to tell which box it will appear in.
Second electron goes through. There is NO WAY ahead of time to tell which box it will appear in.
Etc.
But, as we send more and more electrons through the device, we will find about 30% show up in the left box and 70% show up in the right box.
How do you set up the experiment for only 30% chance in one box and a 70% in the other box?

It can be demonstrated that if an elecron wave goes into two boxes it is in the two boxes until an observer finds it in one of the boxes. So what happened to it in the other box? Did the electron go into another world or does the observer create reality?

“Think&Care”

Since: Oct 07

Location hidden

#317 Mar 18, 2012
Paul WV wrote:
<quoted text>
How do you set up the experiment for only 30% chance in one box and a 70% in the other box?
Setup the beam so that is sp[lit that way.
It can be demonstrated that if an elecron wave goes into two boxes it is in the two boxes until an observer finds it in one of the boxes.
Incorrect interpretation. The electron does not have a definite position until there is an interaction with a complex enough environment. This could be an observer, or it could be detection equipment. Until it has that interaction, to talk about its position (an observable) is inherently problematic. It does not *have* a definite position.
So what happened to it in the other box? Did the electron go into another world or does the observer create reality?
To some extent, that depends on your interpretation of QM whether there are multiple worlds. If you take QM seriously, which I do, then there is a 'split' on each measurement (Everett interpretation). However, it is not consciousness that produces the 'split', but measurement. So it is certainly NOT that an 'observer creates reality'.

“Think&Care”

Since: Oct 07

Location hidden

#318 Mar 18, 2012
Paul WV wrote:
Did the electron go into another world or does the observer create reality?
The electron was not 'in both boxes'. Its position was not defined. It had a probability of being in either box.

Now, the philosophical question is whether all possible outcomes are actual outcomes 'somewhere'. I'm not sure to what extent that is even a meaningful question. How would you test it?

If you do an analysis of the equations of QM, the result is that a measurement makes the wave function 'split' into two (or more) terms. The full wave function has all of these terms, but after the measurement, the different terms do not interact with each other. This is interpreted as there being 'multiple worlds': one for each term in the wave function. Furthermore, the dynamics are such that if you only look at one term, the overall equations of QM hold for just that one term, so each 'world' also obeys QM. Things 'act' like there is a 'collapse' of the wave function to each term.

Now, to avoid this epistomological mess, many people like to think of the wave function 'actually' collapsing, but doing so outside of the rest of QM. So, while epistomologically 'cleaner', this picture is ontologically much worse and, in fact, introduces inconsistencies, as the paper mentioned above point out. To me, it seems better to have a consistent picture with fewer axioms that actually is consistent with measurement that an inconsistent picture with more assumptions. But perhaps that is just me.
Paul WV

Beckley, WV

#319 Mar 18, 2012
polymath257 wrote:
<quoted text>
The electron was not 'in both boxes'. Its position was not defined. It had a probability of being in either box.
Now, the philosophical question is whether all possible outcomes are actual outcomes 'somewhere'. I'm not sure to what extent that is even a meaningful question. How would you test it?
If you do an analysis of the equations of QM, the result is that a measurement makes the wave function 'split' into two (or more) terms. The full wave function has all of these terms, but after the measurement, the different terms do not interact with each other. This is interpreted as there being 'multiple worlds': one for each term in the wave function. Furthermore, the dynamics are such that if you only look at one term, the overall equations of QM hold for just that one term, so each 'world' also obeys QM. Things 'act' like there is a 'collapse' of the wave function to each term.
Now, to avoid this epistomological mess, many people like to think of the wave function 'actually' collapsing, but doing so outside of the rest of QM. So, while epistomologically 'cleaner', this picture is ontologically much worse and, in fact, introduces inconsistencies, as the paper mentioned above point out. To me, it seems better to have a consistent picture with fewer axioms that actually is consistent with measurement that an inconsistent picture with more assumptions. But perhaps that is just me.
Experiments show that if you open slits at the same time on two boxes into which a single electron wave function was placed you find that the single electron was distributed in the two boxes. However if you open the boxes not at the same time and find the electron in one box it is not in the other box and vica versa. So how can the electron be spread out over both boxes if you chose to do the interference experiment or be in only one box if you decide to open the boxes separately to see which box the electron is in? Does the electron being in only one box or both boxes determine which experiment you choose to perform or does your choice change reality and places the electron in only one of the boxes? Note: When the electron is observed as a particle it changes into a particle for all observers and not just the one doing the observing.

“Think&Care”

Since: Oct 07

Location hidden

#320 Mar 18, 2012
Paul WV wrote:
<quoted text>
Experiments show that if you open slits at the same time on two boxes into which a single electron wave function was placed you find that the single electron was distributed in the two boxes. However if you open the boxes not at the same time and find the electron in one box it is not in the other box and vica versa. So how can the electron be spread out over both boxes if you chose to do the interference experiment or be in only one box if you decide to open the boxes separately to see which box the electron is in?
Again, you are not understanding the experiment. In the first case, the electron is 'distributed in the two boxes' in the sense that the wave function showed positive probability in both. Upon measurement that probability is reduced to an actuality of the electron being in one box or the other.

The fundamental problem is, once again, that you are clinging to classical ideas. in this case, you assume the electron has a definite position and that it is in one box or the other, even if we are not measuring position. That is simply not the case. There is a probability of finding the electron in both boxes. Yes, there are experiments where the probability wave in both boxes is relevant to the outcome. In those, the end probabilities are determined from the intermediate probabilities involving the boxes. It is only at an actual measurement that the probabilities become actualities.
Does the electron being in only one box or both boxes determine which experiment you choose to perform or does your choice change reality and places the electron in only one of the boxes?
No, the electron does not have a definite position before the measurement. The measurement makes the probability become an actuality where the electron is in one box or the other.
Note: When the electron is observed as a particle it changes into a particle for all observers and not just the one doing the observing.
Yes, once there is an interaction with a sufficiently complex environment, the probability becomes an actuality.

As far as I can see, your problem is two-fold:
1) You assume that an electron has a definite position at all times.
2) You assume there is a 'cause' for the electron being in one box or the other.

Both of these assumptions are *false* in the context of QM.
Paul WV

Beckley, WV

#321 Mar 18, 2012
polymath257 wrote:
<quoted text>
Again, you are not understanding the experiment. In the first case, the electron is 'distributed in the two boxes' in the sense that the wave function showed positive probability in both. Upon measurement that probability is reduced to an actuality of the electron being in one box or the other.
The fundamental problem is, once again, that you are clinging to classical ideas. in this case, you assume the electron has a definite position and that it is in one box or the other, even if we are not measuring position. That is simply not the case. There is a probability of finding the electron in both boxes. Yes, there are experiments where the probability wave in both boxes is relevant to the outcome. In those, the end probabilities are determined from the intermediate probabilities involving the boxes. It is only at an actual measurement that the probabilities become actualities.
<quoted text>
No, the electron does not have a definite position before the measurement. The measurement makes the probability become an actuality where the electron is in one box or the other.
<quoted text>
Yes, once there is an interaction with a sufficiently complex environment, the probability becomes an actuality.
As far as I can see, your problem is two-fold:
1) You assume that an electron has a definite position at all times.
2) You assume there is a 'cause' for the electron being in one box or the other.
Both of these assumptions are *false* in the context of QM.
The experiments "demonstrate" the electron is either in both boxes or one box depending on which experiment you "chose" to do. It is the observerís choice of experiments which determines whether the electron is in both boxes or only one box. This is a well confirmed experimental fact. Your problem is that you cannot see the enigma and so choose to ignore the experimental evidence that contradicts what you want to believe; much like you do with the idea of God.

“Think&Care”

Since: Oct 07

Location hidden

#322 Mar 18, 2012
Paul WV wrote:
<quoted text>
The experiments "demonstrate" the electron is either in both boxes or one box depending on which experiment you "chose" to do. It is the observerís choice of experiments which determines whether the electron is in both boxes or only one box. This is a well confirmed experimental fact.
No, you are misunderstanding these experiments. The well confirmed experimental fact is that QM is upheld in every case. Instead of the electron being 'in both boxes', the probability wave is. The electrons are only detected at the *end* of the experiment, when the wave has had a chance to interfer (or not).
Your problem is that you cannot see the enigma and so choose to ignore the experimental evidence that contradicts what you want to believe; much like you do with the idea of God.
No, you are misunderstanding what happens in these experiments. Let me focus on a specific example: the quantum 'bomb detector':

http://en.wikipedia.org/wiki/Elitzur%E2%80%93...

In this experiment, a photon is passed through a half-silvered mirror, which allows the photon to go one of two paths: either by a bomb or a different path that avoids the bomb. If the bomb is a 'dud', a photon taking the path by the bomb will not be absorbed, while if the bomb is 'usable', the photon will certainly be absorbed and the bomb will explode. If the photon takes the path away from the bomb, the bomb does not explode in either case.

After, the two paths are brought back together, allowing interference to happen. There are two detectors: A and B. The experiment is adjusted so that interference from the two paths is complete, sending a signal to A and not to B. If only one path is taken, both A and B fire with equal probability. Such a setup can be done in practice.

What happens? Classically, there is no way of knowing there is a usable bomb without it exploding: the path around the bomb gives no information, but the path by the bomb will make the bomb explode. There is no way to determine a bomb is usable and NOT to explode it.

Quantum mechanically, the *probability wave* starts going through *both* paths no matter what. If there is a dud, both paths are fully taken, there is complete interference, and only detector A fires. But if there is a usable bomb, the part of the probability wave going past the bomb is blocked, so no interference happens. In that case, A fires half the time and B fires half the time. But now, if B fires, we *know* the bomb is usable even though it did not explode! We end up detecting half of the usable bombs.

This experiment (obviously not with bombs) has been done and the results agree with quantum mechanics.

This shows the 'reality' of the probability wave even if the photon 'does not go past the bomb'. In reality, the probability wave goes through both paths and either interfers or does not depending on whether there is a bomb. This happens even if only one photon is 'in the aparatus' at a time.

Notice that it is NOT consciousness that determines the results here.

If you have another, specific, experiment that you think shows the electron (or photon) is 'actually' in two places at a time as opposed to the probability wave being so, please give a link.

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