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Author Topic:   the underlying assumptions rig the debate
cavediver
Member (Idle past 3643 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 181 of 246 (323487)
06-19-2006 7:01 PM
Reply to: Message 147 by randman
06-19-2006 1:14 PM


Re: still no substance from you here
Does the waveform span more than one segment of time simultaneously in your view?
This is meaningless. You cannot formulate meaningful questions without actually understanding what you are talking about. I know you think you know what you are talking about but it has zero connect with real physics. You need to learn the basics, else you are going to continually spout gibberish that might, just might sound impressive to some in the lurker gallery.

This message is a reply to:
 Message 147 by randman, posted 06-19-2006 1:14 PM randman has replied

Replies to this message:
 Message 182 by randman, posted 06-19-2006 7:10 PM cavediver has replied

  
randman 
Suspended Member (Idle past 4899 days)
Posts: 6367
Joined: 05-26-2005


Message 182 of 246 (323495)
06-19-2006 7:10 PM
Reply to: Message 181 by cavediver
06-19-2006 7:01 PM


Re: still no substance from you here
Another dodge by you. Typical. You know what the question entails. It entails 2 specific areas.
1. If a present observation makes it clear that we can know what a photon's path is, it appears that the photon, prior to that observation even, follows a single route in a particle-like fashion as seen by no interference pattern.
So does the wave-function encompass or however else you want to say it the points in time prior to the observation? The reason this is a suitable question is because the photon appears in our world to have taken only one path. Keep in mind I am not asking about the many interpretations of whether the photon really does take all paths, but we only see it take one path because of our perspective. I am just talking about the world from the human perspective. The photon's path, even in the past, appears to reflect whether we can have knowledge of that path, correct?
Yes or no will suffice.
2. When "2 particles", for sake of argument, are entangled, they act as one system, correct? At least in some aspects, right? So we can say the wave-function perhaps encompasses both particles or both separated photons as an example (separated meaning appearing so from our perspective). So does the wave-function apply or exist or whatever else you want to say to mean encompass both locations or not?
Edited by randman, : No reason given.

This message is a reply to:
 Message 181 by cavediver, posted 06-19-2006 7:01 PM cavediver has replied

Replies to this message:
 Message 185 by cavediver, posted 06-19-2006 8:02 PM randman has replied

  
Percy
Member
Posts: 22391
From: New Hampshire
Joined: 12-23-2000
Member Rating: 5.2


Message 183 of 246 (323517)
06-19-2006 7:37 PM
Reply to: Message 175 by randman
06-19-2006 6:24 PM


Re: superluminal potentials still under debate
randman writes:
First off, you ought to reread what PaulK stated before assuming I am mischaracterizing his statements. This what he said:
No, my position is that at the quantum level the past is often not written in the first place. From this point of view the "delayed choice" experiments indicate that an indeterminate past can be forced into a determinate state - not that there was a determiante past which changed.
Uh, you better check your own coherence here. Clearly PaulK is not claiming that physicists viewed the experimental results as obvious evidence of causality breaking for which they sought an excuse in indeterminancy. That was your mischaracterization of his views. Another way of describing what you did is that you described his views while mixing in your own commentary without distinguishing which was which.
So let's take this further, along the path of a photon then, it may hit a spot due to circumstances that there is a means of registering the photon's path and so at that point, the photon in the past will have taken a single path. But later down the road, the means to determine which path the photon took could be erased or lost, and so the photon then, over the same stretch of space in the past, will have travelled in superposition and not a single path. In that manner, the past that we deal with does indeed demonstrably change.
The previous two paragraphs were fine, and the first part of this one is fine, too. Where you go wrong is in thinking there was a past that we knew that then changed. But we never knew that past. This is not a case of information we had that changed, but of information we never had. The lesson to be taken from the experiment isn't that causality is broken, but that you can't fool mother nature, who seems to know precisely whether an observation that actually yields information has taken place.
Whether someone knows about the path or not is not really germane to the discussion. In fact, the person that measures the photon when they can tell what it did will see the photon having taken only one path, and another person measuring the same photon but without the means even in principle of knowing from measurement what path the photon took, will see the same past as having shown the particle travel as a wave.
Well, that's a new one! Sounds dead wrong to me, like some weird combination of relativity and quantum theory, but I'll leave it to others to make informed comments.
And the quantum eraser experiment shows that this decoherence is not permanent. That's a key point you are missing here.
This is definitely wrong. For this to be true causality would have to be broken, and it's not.
--Percy

This message is a reply to:
 Message 175 by randman, posted 06-19-2006 6:24 PM randman has not replied

  
Percy
Member
Posts: 22391
From: New Hampshire
Joined: 12-23-2000
Member Rating: 5.2


Message 184 of 246 (323528)
06-19-2006 7:57 PM
Reply to: Message 177 by randman
06-19-2006 6:36 PM


Re: superluminality is a topic of research
randman writes:
There is nothing in entanglement that allows you to know anything about a distant place. You can't even know if the distant particle has even be measured. All you can do is measure your particle and know that if and when they measure theirs, it will have the opposite spin.
This is a contradiction. You admit you can know what a particle's spin is on the other side of the universe; hence you can know something about a distant place.
Say what? Are you even thinking before you type?
Similarly, you fail to realize harnessing the principle of entanglement is in it's infancy. You assume that such and such cannot be done, and ridicule that, but in reality, there are scientists working to see if it can be done all the time. A few years ago, Hawkings said time travel was impossible, and now says that though unlikely, it is possible.
Say what? Are you even reading before you type?
Remember me? I'm the guy who said we all look forward to scientific advances, but that it is important to make sure we plant our flag on solid ground and not in quicksand. I'm telling you not to grasp at the faintest hint of a scientific advance as if it were solidly established progress. By no stretch of the imagination can that be construed as telling science where it can and can't make progress.
Let me say this another way, because you seem to be having trouble grasping this point. What you are doing is finding slight indications (and even misinterpretations of counter-indications) of theories that you wish were true, and then you're claiming that these represent views solidly in the mainstream of science, and that we're all a bunch of dunderheads for telling you that you're wrong. And then you go beyond that and accuse us ridiculing scientific progress.
No one here is questioning what future scientific discoveries might bring. But it definitely is not an accepted view of the science that causality has been broken, and that's all we're telling you. We're not telling you we'll never discover that it's been broken. We're not telling you it's impossible for it to ever be broken. We're just telling you that your claim that science now accepts causality breaking is wrong. Dead wrong.
Right now, we don't really understand fully the mechanism of entanglement and so it is foolish to say that this mechanism cannot be used for such and such.
This gives me an opportunity to make my point yet another way. We're not saying we know that we'll never be able to harness entanglement for FTL communication. We're saying that it is not a view of science that this is possible. We all of us understand the principle of tentativity, and we know that current scientific views are open to change, and so we would never deign to do that. But we do happen to know what science thinks on this topic today, and it isn't anything like what you are claiming.
Lastly, what does superluminality have to do with my arguments in the OP?
If you don't want to talk about it, don't keep bringing it up. It was a side issue related to information until you brought up the ORNL paper and tried to argue that the possibility of superluminary communication was a widely accepted view, and you keep returning to the subject.
--Percy

This message is a reply to:
 Message 177 by randman, posted 06-19-2006 6:36 PM randman has replied

Replies to this message:
 Message 187 by randman, posted 06-19-2006 8:42 PM Percy has replied

  
cavediver
Member (Idle past 3643 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 185 of 246 (323533)
06-19-2006 8:02 PM
Reply to: Message 182 by randman
06-19-2006 7:10 PM


Re: still no substance from you here
Another dodge by you. Typical. You know what the question entails
Randman, I do not dodge, and I do not lie. If I tell you, your question is meaningless, that is what I mean. You have this idea that I have some predetermined idea of how I want the universe, and I'm twisting and evading any evidence that counters that idea. You could not be more wrong.
I study the universe. I have devoted over half of my life to it. And all I do is ask questions. I am only interested in truth. The reason I am so hard on you is becasue you insist on (unintentionally) making misrepresentations and misinterpretations of physics, not helped by much of what you have read from secondary and tertiary "literature".
If I see conclusive evidence of superluminal transfer, it will blow my mind. But I have seen many many claims by many many scientists over the years, and have yet to see anything worth noting.
For all of my life I "knew" that the universe was decelerating in its expansion. Towards the end of my life in academia I hear that the universe is possibly accelerating. Incredulity was quickly replaced by awe and fascination AS THE CONCLUSIVE EVIDENCE CAME IN.
So does the wave-function encompass or however else you want to say it the points in time prior to the observation?
Of course, the wave-function comes in from the infinite past. It evolves through time. That is the entirety of quantum mechanics: the evolution of wave-functions through time. Just like any other function (quantum or classical) defined over the universe, e.g. the metric, thhe em field, the strong field, the weak field, the fermionic matter fields, etc, etc.
the photon appears in our world to have taken only one path
Yes, "appears". The photon's path is not real. It is the result of a question/observation. It is not something in the past, it is the present "understanding" that tries to reconcile what has been observed with what "must have" happened in the past. But it is wrong/misguided. There is only the wave-function.
The photon's path, even in the past, appears to reflect whether we can have knowledge of that path, correct?
No, the "photon's path" IS our "knowledge", our misguided understanding.
So does the wave-function apply or exist or whatever else you want to say to mean encompass both locations or not?
The wave-function of the entangled pair extends over the entire universe.

This message is a reply to:
 Message 182 by randman, posted 06-19-2006 7:10 PM randman has replied

Replies to this message:
 Message 186 by randman, posted 06-19-2006 8:29 PM cavediver has not replied

  
randman 
Suspended Member (Idle past 4899 days)
Posts: 6367
Joined: 05-26-2005


Message 186 of 246 (323559)
06-19-2006 8:29 PM
Reply to: Message 185 by cavediver
06-19-2006 8:02 PM


Re: still no substance from you here
If I see conclusive evidence of superluminal transfer, it will blow my mind.
Well, why do you make this statement. The thread is not about "superluminal transfer", is it? In fact, the thread has nothing whatsoever to do with the idea. I addressed it as a side issue, since you guys brought it up, but continually bring you back to the same points over and over again, only to have had you, imo, dodge them.
Moreover, I have not stated even that there are superluminal particles, nor the opposite. Tachyons and things like that may be real or not. What I have stated is we have the likelihood of a deeper structure within the universe and you yourself speculated on additional dimensions. Now, since we don't know all about these dimensions, it is sort of silly, imo, to speculate that they cannot be used to cause things to occur in 4-D that otherwise would be impossible.
But regardless, that's not what the thread is about, and you know that. The following comments do relate however to the thread.
Yes, "appears". The photon's path is not real.
Fine, but it still leaves either an interference pattern or not in the world we live in, real or not.
Yes, "appears". The photon's path is not real. It is the result of a question/observation. It is not something in the past, it is the present "understanding" that tries to reconcile what has been observed with what "must have" happened in the past. But it is wrong/misguided. There is only the wave-function.
So are you saying all possible paths are always taken? Or are you saying the path of the photon prior to that point of observation is indeterminate?
No, the "photon's path" IS our "knowledge", our misguided understanding.
But it is our understanding of the past that this thread is about. That's something I think you are ignoring.
The wave-function of the entangled pair extends over the entire universe.
Thank you. That was easy, right? So we have something that operates according to rules, but somehow in a mode that can be multi-locational.
Of course, the wave-function comes in from the infinite past. It evolves through time.
What do you mean by "evolve throiugh time"? When we observe via measurements that the photon behaved like a particle, the wave-function didn't really change, or did it? In other words, what we are seeing is a discrete form within the wave-function, right?
Of course, maybe the It from Bit theory Zeilinger advances is right and it somehow did "spend" it's bit and evolved into a collapsed state. To be honest, I can't tell thus far where you stand on this.
But let's say by evolve, you mean it "collapses" or however else you want to say it, so that it from our measurements, one path is taken. That is due to the potential knowledge of it's path as the determining criteria, right?
Or do you disagree with that?
OK, let's say then that this changes and the ability to know what path the particle takes is scrambled, the particle then shows an interference pattern, right? Indicating wave-like propagation, right?
Well, looking at the quantum eraser experiment, what is the distance between when the particle can be measured and when the particle could not be measures was, say, a light-year apart. Isn't it true that someone that would observe or measure the photon in the first year see it taking a single route as a particle, and the person in the 2nd year would see it as taking all possible routes. So looking back on the same event, the photon's path, from 2 vantage points in time yields differing "realities", one with the photon taking one path and another with the photon taking all paths, right?
Edited by randman, : No reason given.

This message is a reply to:
 Message 185 by cavediver, posted 06-19-2006 8:02 PM cavediver has not replied

  
randman 
Suspended Member (Idle past 4899 days)
Posts: 6367
Joined: 05-26-2005


Message 187 of 246 (323570)
06-19-2006 8:42 PM
Reply to: Message 184 by Percy
06-19-2006 7:57 PM


Re: superluminality is a topic of research
You guys are the ones that bring up superluminality, not me, percy.
Moreover, you are ignoring this statement by Wheeler:
Stronger than the anthropic principle is what I might call the participatory principle. According to it we could not even imagine a universe that did not somewhere and for some stretch of time contain observers because the very building materials of the universe are these acts of observer-participancy. You wouldn't have the stuff out of which to build the universe otherwise. This participatory principle takes for its foundation the absolutely central point of the quantum:
No elementary phenomenon is a phenomenon until it is an observed (or registered) phenomenon.
Cosmic Search Vol. 1, No. 4 - FORUM: John A. Wheeler
Rather than pretend he didn't say this, or doesn't believe this, or trump up some unrelated BS about Paul Davies that has no relevance whatsoever, why don't you take a stab at explaining what you think Wheeler meant?
You are fond of saying no scientist says what I am saying, and yet right here Wheeler advances the observer-participancy principle, and repeats one of his sayings:
No elementary phenomenon is a phenomenon until it is an observed (or registered) phenomenon.
What experimental basis do you think he is alluding to when he says this is "the absolutely central point of the quantum:".
You keep telling me it isn't the central point of the quantum. Well, tell me why I should believe you. Tell me what you think Wheeler is really saying. Post something of substance related to the experiments he draws this from, please.
Edited by randman, : No reason given.

This message is a reply to:
 Message 184 by Percy, posted 06-19-2006 7:57 PM Percy has replied

Replies to this message:
 Message 190 by Percy, posted 06-20-2006 1:13 AM randman has replied

  
Iblis
Member (Idle past 3895 days)
Posts: 663
Joined: 11-17-2005


Message 188 of 246 (323571)
06-19-2006 8:43 PM
Reply to: Message 144 by Larni
06-19-2006 10:03 AM


Re: more on delayed-choice experiments
Larni writes:
Does this mean it is a wave until it gets messed with?
No, not exactly. I'm sorry, I realize some of the language I've used to describe this process could lead to that conclusion. It's not really a bad model, certainly better than this backward-in-time delusion, but it still implies that the photon is sometimes a particle and sometimes a wave, which is basically what the experiments disprove. It gets even worse when you realize that the ALWAYS a particle / ALWAYS a wave language I would be happy to replace it with is still technically false. What it actually is is a waveform, thats a unit of energy which has some of the properties we associate with a standing wave and some of the properties we associate with a solid particle.
If you are really trying to follow this argument then I guess the best thing I can do is to delve into what an "interference pattern" actually consists of. Randy is depending on his audience not knowing this part for a bit more than half his points; he's essentially making the argument that because an interference pattern was the original proof that light is a waveform rather than a substance, therefore all waves must produce an interference pattern under all circumstances, and anything that doesn't is de facto not a wave.
Let's go to the beach first, and watch ordinary water waves crashing together. When two crests meet, we end up with a single crest quite a bit higher than either original wave. Same with two troughs, we get an even deeper trough. These kinds of combinations are examples of constructive interference. On the other hand, when a crest meets a trough, we get a much smaller crest or a much shallower trough, depending on which wave had the most variance from the median. This is an example of destructive interference. Notice we havent specified any pattern yet?
Now let's find some nice still water somewhere and chuck a couple of pine cones in at the same time near one another. We are making our own systems of waves, so that we can watch the troughs and crests meeting one another and engaging in both constructive and destructive interference at once. This produces a particular kind of pattern, consisting of nodes (destructive interference) and anti-nodes (constructive interference), viewed in this case as ovals and lines. Unlike the waves that make them up, the nodes and anti-nodes don't seem to move around much, this is called a standing wave pattern. Notice that the phenomenon is caused by waves meeting one another and ends as soon as we run out of waves to meet and feed the system?
Now we are ready for the Young Double-Slit experiment. This is how we prove that light is more like a wave than a stream of particles. If we set up a bulletproof closed box with two slits in the front, and shoot at it with a machine-gun for a while, and then open it up, we find that the bullets that make it through the slits impact the back wall in two places, one behind each slit. On the other hand, if we use a big firehose to spray colored water at it, we find that the waves of water split when they hit the slits but recombine on the other side, and this recombination, consisting as it must of both constructive and destructive interference, leaves a nice pattern of nodes and anti-nodes in the single area affected on the far wall.
Now, if instead of all this wacky stuff we just shine light through the two slits, light being a wave, we get not two images on the far wall but one, and that one has lines of light and dark to it representing the constructive and destructive interference caused by the wave, which is split into two by the slits, recombining. This isn't terribly surprising as we already know light is a wave. It doesn't prove that the wave does not consist of particles either, remember we used water waves to set this standard and they do consist of particles. The machine-gun fire is the odd man out here, because the little individual bullets never form a wave.
No, the surprising part is if we contrive to send one single quantum of light at the slits. If it is a particle, it will have to go in one slit or the other. And if it isn't, then what the hell is it? Turns out it too is a wave. We know this because as long as we leave both slits open and allow the recombination to happen naturally, we get an interference pattern on the far wall. This is, kind of novel, in that all the natural waves we can measure at the beach or in our stereo or wherever move through something, little particles wacking into one another and imparting energy which is what is getting passed on in the wave. Light consists of energy doing this same phenomenon without any medium to be passing through. The photon is not, as we might have hoped, the medium by which energy is passed on, it's just the absolute smallest standing waveform that can exist in a universe shaped the way ours is.
This really annoyed the quantum physicists. It's like finally cracking open some sort of puzzle box and discovering there is another box inside the same size. First of all, obviously, another box is bad enough. But worse that that, the same size!?! How can it be the same size and still fit inside the other box? The photon is exactly like this. When we split it, we get two photons of the same size but half the frequency (twice the wavelength.) This is how waves behave, not particles. How can the smallest consistent unit of something not be a particle of some kind? What the hell is this stuff made out of, then?
So they tried to trick it. The original quantum-tricking double-slit experiment consists of sticking an arrangement of telescopes or cameras or polarizers or detectors of some kind into the box. Note that these are solid objects, the only solid in the path before this was the back wall. Anyway, it tricked them right back! With these additions to the experiment, the photon no longer produces an interference pattern on the back wall. This is said to "prove" that it is only a particle under these circumstances. This is about the point where Wheeler and his buddies get a little paranoid. It appears to know, whether we are looking at it, or not!!!
So they tried to trick it again. This is where the delayed-choice comes in. At the point in time where the photon is theoretically either passing through both slits or else just one, the detector array is not yet in place. It snaps into place just before the photon or photons would be arriving at either one or both sides of the detector, well before the back wall where the interference pattern either would or would not be displayed.
If we hold on to the classical idea of a particle either splitting in two or not splitting in two, with the additional fetish that it knows we are looking at it when we are looking at it, it should be split at this point, having traveled in through both slits, and we should be able to catch it being in two places at once. But no, it doesn't leave an interference pattern under these circumstances either. It appears to know, that we are going to be looking at it, before we actually do!!! Wheeler basically stops doing useful math at this point and begins building analogies out of party games where his guests conspire together to cheat him into thinking he knows things he doesn't. Very sad, and also super-funny
Adding in the "quantum eraser" solves the whole problem quite handily though. If we intentionally split the photon, so that we are quite sure it is going through both slits, and then pop up the detector array, it still doesn't produce an interference pattern on the back wall. It then becomes rather obvious what is happening. The interference pattern only appears as a result of the recombination of the split waveform, this only happens once during the experiment. Without the detector, it happens at the back wall. With the detector, it happens where? At the detector. On one side. Giving the impression that the waveform is sometimes a particle, even though it never is.
I'm sure this has been hard to follow, so now I'm going to oversimplify even more. If we block one of the slits, the interference pattern disappears. This does not prove the waveform has become a particle, it just proves it never had to recombine. It doesn't make any difference whether the slit is blocked when we generate the photon, what matters is whether it is blocked when the waveform tries to go through it. Exactly WHEN the blockage occurs doesn't effect the final result. What does effect the final result is exactly WHERE the recombination takes place. Interfering with the process before the wall is equivalent in result, but not in technique, to blocking one slit. Either way, there will be no interference pattern back there.
The final proof will be in the pudding though. The next step is to see if we can come up with a way to measure the interference pattern AT the detector. Based on the current logic, it should be there. But we don't know how to see it without stopping the wave. Actually stopping the wave will certainly produce the pattern though, which will tell us nothing. We need to come up with some way to stop it and not stop it at the same time. In order to do this, or at least keep doing stuff like this, we need for the public to invest big gobs of money in particle accelerators and supercomputers and time for us to use them and stipends to buy us whiskey. Seeing as how most of this gibberish isn't really interesting to investors as is, we use catch-phrases like "teleportation" and "quantum computing" and "superluminal" to keep them excited. But we draw the line at bad theology
(Yes I know, still reduced to inanities in the end. But at least these don't paint an intentionally false picture of the realities of Quantum Mechanics.)

This message is a reply to:
 Message 144 by Larni, posted 06-19-2006 10:03 AM Larni has replied

Replies to this message:
 Message 189 by randman, posted 06-19-2006 9:08 PM Iblis has not replied
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randman 
Suspended Member (Idle past 4899 days)
Posts: 6367
Joined: 05-26-2005


Message 189 of 246 (323580)
06-19-2006 9:08 PM
Reply to: Message 188 by Iblis
06-19-2006 8:43 PM


Re: more on delayed-choice experiments
It appears to know, that we are going to be looking at it, before we actually do!!! Wheeler basically stops doing useful math at this point and begins building analogies out of party games where his guests conspire together to cheat him into thinking he knows things he doesn't. Very sad, and also super-funny
So Wheeler is an ignoramus as well, eh? Hmmmm....why don't you let me know when your name is in the encyclopedia for your accomplishments in physics. At least I know I am keeping good company.
Britannica
Adding in the "quantum eraser" solves the whole problem quite handily though. If we intentionally split the photon, so that we are quite sure it is going through both slits, and then pop up the detector array, it still doesn't produce an interference pattern on the back wall. It then becomes rather obvious what is happening.
Does it? Those conducting the experiment disagree with what you claim is causing the interference pattern to appear or disappear. They didn't expect it to appear. They expect it to appear only if there is no way in principle to tell which way the photon went. But let's look at your explanation first.
Exactly WHEN the blockage occurs doesn't effect the final result. What does effect the final result is exactly WHERE the recombination takes place.
So you admit the delayed-choice works even before the choice is made?
So let's hear Mandel's take on what has changed to affect the final result.
The comparison of arrival times need not actually be performed to destroy the interference pattern. The mere "threat" of obtaining information about which way the photon travelled, Mandel explains, forces it to travel only one route. "The quantum state reflects not only what we know about the system but what is in principle knowable," Mandel says.
http://www.fortunecity.com/emachines/e11/86/qphil.html#
Zeilinger echoes this same observation:
A necessary condition for quantum interference is that the experiment must be performed in such a way that there is no way of knowing, not even in principle, which of the two slits the particle passed through on its way to the screen.
Home – Physics World
In other words, if we know, there is no interference pattern and if we do not know, the interference pattern appears. That's what these guys are saying, right?
Edited by randman, : No reason given.

This message is a reply to:
 Message 188 by Iblis, posted 06-19-2006 8:43 PM Iblis has not replied

  
Percy
Member
Posts: 22391
From: New Hampshire
Joined: 12-23-2000
Member Rating: 5.2


Message 190 of 246 (323688)
06-20-2006 1:13 AM
Reply to: Message 187 by randman
06-19-2006 8:42 PM


Re: superluminality is a topic of research
randman writes:
You guys are the ones that bring up superluminality, not me, percy.
Rather than pretend he didn't say this, or doesn't believe this, or trump up some unrelated BS about Paul Davies that has no relevance whatsoever, why don't you take a stab at explaining what you think Wheeler meant?
Remember, you're arguing for causality breaking. Where in your Wheeler quote do you see an argument for causality breaking?
The same is true of your Feynman quote. Where in that quote do you see an argument for causality breaking?
I think it's a mystery to everyone why you see arguments for causality breaking everywhere you look, but no one sees them but you.
It should tell you something that you can't find anyone anywhere making explicit statements that causality breaking has been demonstrated. I recall now that you went on and on a few months ago arguing that TalkOrigins misrepresented the two definitions of evolution, also something that only you could see. I think the support you find for your positions in material that actually provides no support is just some little habit you've somehow developed, and I'm not sure it makes any sense to try to raise evidence and rational arguments against it.
--Percy

This message is a reply to:
 Message 187 by randman, posted 06-19-2006 8:42 PM randman has replied

Replies to this message:
 Message 191 by randman, posted 06-20-2006 2:04 AM Percy has replied

  
randman 
Suspended Member (Idle past 4899 days)
Posts: 6367
Joined: 05-26-2005


Message 191 of 246 (323702)
06-20-2006 2:04 AM
Reply to: Message 190 by Percy
06-20-2006 1:13 AM


Read Iblis' last post
Percy, I suggest you read Iblis' last post, not because he agrees with me, but because of his derision of "Wheeler and his friends" who have the same view of what occurs in the 2-slit on his part in attacking their and my view because you guys, as usual, start off arguing no one in science agrees with or comes close to agreeing with the basic views I present, even though it is from these guys that I learned the science does show these things.
It's not only arrogant of you and others, but it's wrong and offensive. These could be good discussions, if you treated them with respect and intellectual honesty. Instead you guys resort to things like deriding men like Wheeler as looney, and similar tactics, and yet none of you, not one, can adequately offer any other plausible explanation for what occurs in these experiments.
I suggest you reread the quotes I provided from Wheeler, Mandel and Zeilinger and carefully consider what they are saying, not inserting some label of something you don't even understand, but actually consider what their claims are. They all claim that potential present knowledge affects what the past indicates, or put it another way, what occured in the past in our universe of experience. The photon's path is revealed in our universe of experience by what can be said about it.
Until you take the time to learn what they are talking about, you are just blowing hot air.
Why not take some time to see what they are talking about, and then we can have a much more fruitful discussion?
fyi, Wheeler's quote again (hint: he quotes someone else in it)
Stronger than the anthropic principle is what I might call the participatory principle. According to it we could not even imagine a universe that did not somewhere and for some stretch of time contain observers because the very building materials of the universe are these acts of observer-participancy. You wouldn't have the stuff out of which to build the universe otherwise. This participatory principle takes for its foundation the absolutely central point of the quantum:
No elementary phenomenon is a phenomenon until it is an observed (or registered) phenomenon.
Wheeler takes Bohr's statement and takes it to a new level asserting that "you wouldn't have the stuff out of which to build the universe" without observer participancy. Now that conclusion may or may not be a stretch, but he has a good reason based on these experiments for stating it.
The statement "No elementary phenomenon is a phenomenon until it is an observed (or registered) phenomenon," in the context of this entire quote about how the stuff that the universe consists of is made up of observer participancy is that the universe itself takes on real form only when it is an observed or registered phenomenon. I think some others were just saying no phenomenon is real, but Wheeler extends this to the building blocks of the real universe.
So what does this mean in respect to the past and why make such outlandish statements? The reason is that
"the central point of the quantum" is that discrete form, physical reality, only occurs after observation, and this does include the past.
Wheeler is the one that posed the original delayed-choice experiment as a thought experiment concerning a photon travelling from billions of light-years away. He specifically pointed out the conundrum of how the way we decide to measure the photon determines which path the photon took (in other words what the past was). Wheeler's solution to the causality here is to state the photon didn't exist until observation, and that's one perspective. I think cavediver even said:
The photon's path is not real.
But he didn't elaborate.
Wheeler is relying on the observation that how we observe the photon appears to dictate what path the photon took, and thus the past, indeterminate or determinate or however you want to look at it, is formed in part by the present potential knowledge (in the universe of our experience).
Edited by randman, : No reason given.
Edited by randman, : No reason given.

This message is a reply to:
 Message 190 by Percy, posted 06-20-2006 1:13 AM Percy has replied

Replies to this message:
 Message 197 by Percy, posted 06-20-2006 3:17 AM randman has replied
 Message 198 by Percy, posted 06-20-2006 3:20 AM randman has replied

  
PaulK
Member
Posts: 17822
Joined: 01-10-2003
Member Rating: 2.2


Message 192 of 246 (323709)
06-20-2006 2:24 AM
Reply to: Message 176 by randman
06-19-2006 6:26 PM


Re: Zeilinger's view
quote:
That's correct, but you have to realize that "our information changes" includes the information about what constitutes the past.
You have to realise that it DOESN'T include information that we already have - Zeilinger is quite clear about that. It doesn't even include information we're going to get in the future !g

This message is a reply to:
 Message 176 by randman, posted 06-19-2006 6:26 PM randman has replied

Replies to this message:
 Message 193 by randman, posted 06-20-2006 2:31 AM PaulK has replied

  
randman 
Suspended Member (Idle past 4899 days)
Posts: 6367
Joined: 05-26-2005


Message 193 of 246 (323712)
06-20-2006 2:31 AM
Reply to: Message 192 by PaulK
06-20-2006 2:24 AM


Re: Zeilinger's view
What do you mean by information we already have? Did you understand my question and analysis about the path of the photon at any particular stage.
All that matters is whether the potential for knowing the photon's path is, right? So if someone can know it's path, it will indicate and have travelled in the universe of our experience on one path, right?
But that same photon down the road if someone encounters it, and there is not the ability to determine it's path, then it will indicate in our universe a superposition and wave-like propogation, right?
So the same photon can and does probably, along the same path, travel only a single path in our universe, and then later can have travelled all paths, and back again, and so forth, for as long as the potential AT THAT POINT IN TIME to know it's path changes.
Do you understand that?

This message is a reply to:
 Message 192 by PaulK, posted 06-20-2006 2:24 AM PaulK has replied

Replies to this message:
 Message 194 by PaulK, posted 06-20-2006 2:44 AM randman has replied

  
PaulK
Member
Posts: 17822
Joined: 01-10-2003
Member Rating: 2.2


Message 194 of 246 (323713)
06-20-2006 2:44 AM
Reply to: Message 193 by randman
06-20-2006 2:31 AM


Re: Zeilinger's view
quote:
What do you mean by information we already have?
Exactly what I said. According to Zeilinger, information we already have is fixed - you can't change anything that we already know.
quote:
Did you understand my question and analysis about the path of the photon at any particular stage.
Did you understand the quotes I gave from Zeilinger ?
quote:
All that matters is whether the potential for knowing the photon's path is, right? So if someone can know it's path, it will indicate and have travelled in the universe of our experience on one path, right?
But that same photon down the road if someone encounters it, and there is not the ability to determine it's path, then it will indicate in our universe a superposition and wave-like propogation, right?
Not quite - according to Zeilinger you only get the wave-like behaviour if the path information is completely unavailable. If someone in the future is going to measure it then that is what will be seen - no matter what could be determined. You can only see the wave-like behaviour if the path information is irrevocably lost without anyone seeing it.
Read the quotes I gave again.

This message is a reply to:
 Message 193 by randman, posted 06-20-2006 2:31 AM randman has replied

Replies to this message:
 Message 195 by randman, posted 06-20-2006 2:52 AM PaulK has replied

  
randman 
Suspended Member (Idle past 4899 days)
Posts: 6367
Joined: 05-26-2005


Message 195 of 246 (323716)
06-20-2006 2:52 AM
Reply to: Message 194 by PaulK
06-20-2006 2:44 AM


Re: Zeilinger's view
According to Zeilinger, information we already have is fixed - you can't change anything that we already know.
Please substantiate that. Where does he say "information is already fixed"? The quantum eraser shows the exact opposite, that information can be erased.
You can only see the wave-like behaviour if the path information is irrevocably lost without anyone seeing it.
Nope, not at all. You exhibit a major misunderstanding of what the quantum eraser experiment shows. It shows that indeed you can see a change in the photon's path back again; that once collapsed, the photon's path can become uncollapsed.
And what is the determining factor? Whether we can know or not know it's path.
Edit to add. Zeilinger in following the Copenhagen interpretation does indeed think in terms of the elementary particle have a Bit and so once spent, it is fixed. This is, of course, because he believes the there is an interaction somehow with the observer, which is why he makes the comments not just on a mechanical observer but suggests the importance of whoever operates the experiment.
However, he does indeed think the past is formed by the present questions; the photon's path is determined by the observer's question, and so implies an actual connection between conscious observation and reality.
I don't deny that this could be true and do believe there is a connection between consciousness and physical reality, but I'd have to hear him out on this a little more to agree fully with you.
For example, what if the information is lost. Say the initial observers are all dead. Does the photon revert back to wave-like status in it's path?
In the quantum eraser experiment, it is clear that if one were to measure the photon at one point, it would have travelled along one path. I think in the context of what I am talking about, you are not seeing the significance of that. Imo, the causal effect of the photon at that point in time, whether observed or not, is likely to be the effect of the photon in a collapsed state, and history at that point in time would reflect that. Now, you can say it is indeterminate, like Wheeler, but if you do, you are also stating that perhaps a great deal of the past is indeterminate.
So when the photon enters a zone where at that point in time, it cannot be determined which path it took, the photon then will have taken all possible paths. Imo, the causal effect then is that in the past, it took all possible paths.
So we see the photon taking over the same stretch of path different physical manifestations depending on the observer's ability to know the path.
Moreover, are there any experiments that show someone measuring a photon without the one measuring the photon being able, even in principle, the photon's path? That would settle this issue between you and I here but may be hard to construct.
For example, if your claim is correct, we should see some photons that never exhibit wave-like behaviour at all, and I don't think that is the case.
Secondly, I am not sure Zeilinger beleives exactly what you think he does. I think you could be taking some things out of context. I read that paper and did not get that from him. It could, for example, that he beleives elementary particles can take on Bits somehow. So a collapsed photon for one observer could down the road be measured by another who has no way of knowing the photon's path before, and see the photon having taken all possible paths, even for the time period someone else measured it as a single path. If we are going with observer participancy, then this makes sense.
Otherwise, why don't we routinely see photons directed at 2-slits pass through only one slit as a particle instead of a wave? The idea that once a particle collapses into one path so to speak, that this path is fixed and the photon thus never acts as a wave is not correct, imo.
Edited by randman, : No reason given.
Edited by randman, : No reason given.
Edited by randman, : No reason given.

This message is a reply to:
 Message 194 by PaulK, posted 06-20-2006 2:44 AM PaulK has replied

Replies to this message:
 Message 196 by PaulK, posted 06-20-2006 3:04 AM randman has replied
 Message 204 by PaulK, posted 06-20-2006 3:49 AM randman has replied

  
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