Schrodinger's Cat

[Danneskjold]

The setup is this:

A cat is in a box with some sort of thing that has an exactly 50% chance of killing it or leaving it completely unharmed.

The basic claim, as I understand it, is that a cat exists in multiple states, that being both dead and alive, at once as long as nobody has observed it. Once it is observed, its state is decided. I'm trying to figure out what water this holds if any. Any ideas?

[Dragonfly]

The setup is this:

A cat is in a box with some sort of thing that has an exactly 50% chance of killing it or leaving it completely unharmed.

The basic claim, as I understand it, is that a cat exists in multiple states, that being both dead and alive, at once as long as nobody has observed it. Once it is observed, its state is decided. I'm trying to figure out what water this holds if any. Any ideas?

The Schrödinger cat thought experiment is based on the quantummechanical notion of superposition of states. The most famous example is no doubt the double slit experiment: a beam of photons or electrons passes through two narrow slits, close to each other and hit a screen (or some other kind of detector), producing an interference pattern (light and dark bands, or bands of detector hits and empty bands). This is of course the expected behavior of light, but the fact that such interference is also produced with "real" particles like electrons shows that such particles also can behave in a wave-like manner. The weird part of the experiment is that when you decrease the intensity of the beam so that only one photon or one electron at a time passes the slits, you still get an interference pattern. This goes against our classical intuition: one thinks that an electron has to go through one of both slits, but how can it then interfere with itself? Somehow it must "know" the existence of the other slit, or pass through both slits at the same time. In QM we can describe a physical system by a state vector, for example state A can describe an electron passing through slit 1 and state B an electron passing through slit 2. A situation in which interference occurs will then be described by a state C which is the superposition of states A + B. This superposition state doesn't tell us through which slit the electron passes, it only can tell us the probability that the electron will hit the screen (detector) at a certain place, and that probability is calculated by adding the possible pathways coherently, in some places there will be constructive interference (bright band, lots of hits) and on other places destructive interference (dark band, no hits). Now we might try to find out which path an electron follows by placing a detector near one of the slits. But then an interesting thing happens: as soon as we know the path of the electron, no matter how subtle our measurement may be, the interference pattern disappears and there is no longer a superposition C of states, but only state A or state B. So we may distinguish two kinds of states: single states like A or B, which correspond to our classical intuition (a particle goes via path 1 or via path 2) and superposition states, where we don't know which path is followed. This isn't merely a lack of knowledge of the "real situation": the interference effect shows that in a sense the particles are delocalized over the two paths.

Schrödinger's cat example was meant as an illustration of the problem that it was not clear at the time why superposition of macroscopic states could not exist, as it seemed to follow automatically from the QM formalism. We now know that such coherent superpositions of states can only exist when they are isolated, not interfering with the environment. Such an isolation is reasonably well possible with microscopic systems involving a few particles, but becomes increasingly difficult to maintain with larger system and is virtually impossible with macroscopic systems: even under the best conditions there are always stray electrons, photons, molecules which act as the pathway detector in the two-slit experiment: information leaks away to the environment, destroying the coherence. This decoherence in fact happens extremely fast, so in a system with a real cat any possible coherent superposition between the two states which would lead to a dead cat and to a cat that is alive is destroyed long before anyone looks into the box. The calculation of the probability of the outcome is still the same, but now no longer refers to a coherent state (a rather mysterious combination of a dead cat and a cat that is alive), but to a statistical ensemble of dead/alive states, which means that if we repeat the experiment many times, we'll find in approximately 50% of the cases that the cat is dead and in 50% that the cat is alive, corresponding to our classical intuition.

In the early years of QM it was thought that it was the measurement of the system that destroyed the superposition of states (the so-called collapse of the wavefunction), which lead to much confusion about what exactly a "measurement" is, and the idea that it had something to do with information reaching a consciousness. Now it is true that an appropriate measurement will destroy a superposition (like the measurement in the double-slit experiment), but in many cases the superposition has already been destroyed by decoherence long before, one could say that the environment has made a measurement of the system. Decoherence is therefore also a very big problem for the construction of a quantum computer, which is based on the superposition of states, and it is than also still an open question whether such a computer is feasible on any practical scale.

[bmacwilliam]

"The weird part of the experiment is that when you decrease the intensity of the beam so that only one photon or one electron at a time passes the slits, you still get an interference pattern."

In other words, in a very real sense, the single electron must have been in two places at one time. In order to create an interference pattern, the electron must pass through both slits and interfere with itself.

"Now it is true that an appropriate measurement will destroy a superposition (like the measurement in the double-slit experiment), but in many cases the superposition has already been destroyed by decoherence long before, one could say that the environment has made a measurement of the system."

Also, I've heard it described as the POSSIBILITY of conscious observation changes the outcome and collapses the probability function, NOT the observation itself - wierd stuff.

Edit: Actually I don't remember how or if the consciousness matters in all of this - I'll have to look that up, but what was very interesting was that the observational POSSIBILITY was important, not the observation itself.

In other words "What quantum mechanics tell us is that nothing is real and that we cannot say anything about what things are doing when we are not looking at them. "

So it seems the Copenhagen interpretation of QM is not compatible with Objectivism.

Bob

Edited February 7, 2007 by Bob_Mac

[bmacwilliam]

"I'm trying to figure out what water this holds if any. Any ideas?"

To answer this question is pretty simple but the implications aren't. It holds water completely in the sense that experiments show results that have no common sense or conventional explanation. Basically if QM (Copenhagen) is correct, the cat is truly both alive and dead. Or at least, no knowledge of the system inside the box will ever be sufficient to predict the outcome - it is truly indeterminate. This is very different than us just not knowing because we haven't looked yet. The actual act of observation forces the cat into one state or the other.

Certain things can be in two places at once. Observation, and the possibility of observation, affects reality. Even logic itself is affected.

"it may be that it is not enough to say that a statement is either true or false, we may have to introduce a three-valued quantum logic which allows the additional status of 'undecided'. "

Some "things" can travel faster than light. The idea of non-locality has been shown where particles "communicate" over large distances totally instantaneously.

Anyway, physicists argue about all aspects of this stuff, and not much seems clear to me other than this:

Causality is not what we think it is...

Time is not what we think it is...

Distance/motion is not what we think it is...

and the list goes on...

Mostly as I see it, contrary to O'ism.

Edit: I have argued, and I still believe, that Quantum Mechanics is not compatible with Objectivism, and even with just an undergraduate education in QM I can confidently conclude that an Objectivist Physicist is a contradiction in terms, but I've been challenged on this. There are alternate interpretations, but none that really "hold water" in the sense that QM does. Personally,I believe Physics first when it contradicts philosophy.

Bob

Edited February 7, 2007 by Bob_Mac

[Laure]

I don't know QM, but I've heard that QM has been applied in real technology and that it "works" so I guess it's at least partially true. I wonder if the real problem is with how people explain it, the wording they use. I would love to encounter an Objectivist Physicist who could explain QM in a way that made sense, but then, at a microscopic scale sometimes common sense doesn't seem to apply.

As for Schrodinger's Cat, I don't see why we can't say "We cannot know the state of the cat until we look in the box", and NOT "The cat is both alive and dead, and the act of our looking at it causes it to become one way or the other" - which makes absolutely no sense.

[Dragonfly]

To answer this question is pretty simple but the implications aren't. It holds water completely in the sense that experiments show results that have no common sense or conventional explanation. Basically if QM (Copenhagen) is correct, the cat is truly both alive and dead. Or at least, no knowledge of the system inside the box will ever be sufficient to predict the outcome - it is truly indeterminate. This is very different than us just not knowing because we haven't looked yet. The actual act of observation forces the cat into one state or the other.

No, that is not the conclusion - see my previous post. In macroscopic systems decoherence will very quickly destroy such coherent superpositions, even long before they'd reach cat-sized systems, so the cat is really either dead or alive. Such superpositions do occur however at atomic scales and can be created with clever experiments for somewhat bigger systems, which are therefore called "cat states". Such cat states would for example be an essential part of a quantum computer.

Certain things can be in two places at once. Observation, and the possibility of observation, affects reality. Even logic itself is affected.

Not so fast... that a wavefunction is non-local is not the same as saying that an electron is a two places at the same time, that would be trying to reduce it to some kind of classical (even if rather weird) interpretation, the position of the electron is just not defined. And that the possibility of observation changes the outcome of an experiment indicates that the role of consciousness is a red herring.

Some "things" can travel faster than light. The idea of non-locality has been shown where particles "communicate" over large distances totally instantaneously.

Here you should also be careful with the interpretation of the EPR/Bell experiments, this is rather tricky stuff. But it is certain that it is not possible to use EPR correlations to transmit information faster than light, and the principle of special relativity is not violated.

[Dragonfly]

I don't know QM, but I've heard that QM has been applied in real technology and that it "works" so I guess it's at least partially true.

You bet it can be applied in real technology! The computer that you use to type your messages wouldn't exist without QM (neither would a lot of other things that you use daily). It is by far the most successful physical theory ever, with all its predictions experimentally confirmed with a sometimes astounding accuracy. The big problem is that the results are sometimes so counterintuitive, but as all experiments confirm its predictions, the only logical conclusion is that reality itself is counterintuitive if we look closely enough. That can be explained by the fact that we have evolved and grown up in a world in which such weird behavior is invisible, and that is the world that has formed our intuition (for example that things are always perfectly localized), that can be so strong that we're unwilling to give it up, even when confronted with uncontrovertible evidence to the contrary.

I wonder if the real problem is with how people explain it, the wording they use. I would love to encounter an Objectivist Physicist who could explain QM in a way that made sense, but then, at a microscopic scale sometimes common sense doesn't seem to apply.

Well, that's exactly the point, we can't sugarcoat the pill. Every attempt to give an interpretation that seems to take away some weird aspect, will result in the emergence of some other weird aspect (which is often underplayed by the proponent of that interpretation); that's the law of conservation of weirdness.

As for Schrodinger's Cat, I don't see why we can't say "We cannot know the state of the cat until we look in the box", and NOT "The cat is both alive and dead, and the act of our looking at it causes it to become one way or the other" - which makes absolutely no sense.

See my other posts with regard to the poor beast.

[Michael Stuart Kelly]

Dragonfly,

I like your explanations. They are fact-based. I admit to being not well read about QM, but the more I read about it, the more I believe that the reality of the subatomic field (and macroscopic field) presents new principles, and new applications of old ones, that are not present at midrange where human beings exist.

I think it is a mistake to take a general principle like causality (which is so all-inclusive that it is almost meaningless when it is taken as a stand-alone principle), see how it works midrange, then try to force observed subatomic behavior into it. I see nothing wrong with noting that something always causes something else at a subatomic level. What causes what is the big question and I see nothing wrong with discovering such causality by the usual methods of speculation/hypothesis/theory and trial-and-error.

Michael

[James Heaps-Nelson]

Objectivist metaphysics is based in identity, not causality. There are any number of epistemological assumptions we take from the macroworld to the micro:

1. Separability of entities from their surrounding space.

2. Constancy of things like time, length and velocity.

3. The same event can't have two different outcomes.

Incidentally, although QM and relativity have been puzzled over by many Objectivists. However, I think that many subatomic events that are strictly a result of Standard Model considerations are just as puzzling:

Why does one atom radioactively decay and not another?

Why can the same particle collision yield two separate sets of byproducts that obey physical conservation laws of energy, charge, angular momentum etc.

In any case, most Objectivists use an entity-action causation model, because for most things it is better than a Humean event-event model. The only place I've seen entity-action causation fleshed out in the Objectivist literature is in Peikoff's discussion in OPAR concerning dropping a rubber ball on the pavement and substituting an egg.

Jim

Jim

[Ellen Stuttle]

[T]hat's the law of conservation of weirdness.

That made my day. Love it! And I know another resident of this house who will love it also when I tell it to him.

Ellen

___

[Brant Gaede]

I don't know QM, but I've heard that QM has been applied in real technology and that it "works" so I guess it's at least partially true.

You bet it can be applied in real technology! The computer that you use to type your messages wouldn't exist without QM (neither would a lot of other things that you use daily). It is by far the most successful physical theory ever, with all its predictions experimentally confirmed with a sometimes astounding accuracy. The big problem is that the results are sometimes so counterintuitive, but as all experiments confirm its predictions, the only logical conclusion is that reality itself is counterintuitive if we look closely enough. That can be explained by the fact that we have evolved and grown up in a world in which such weird behavior is invisible, and that is the world that has formed our intuition (for example that things are always perfectly localized), that can be so strong that we're unwilling to give it up, even when confronted with uncontrovertible evidence to the contrary.

I wonder if the real problem is with how people explain it, the wording they use. I would love to encounter an Objectivist Physicist who could explain QM in a way that made sense, but then, at a microscopic scale sometimes common sense doesn't seem to apply.

Well, that's exactly the point, we can't sugarcoat the pill. Every attempt to give an interpretation that seems to take away some weird aspect, will result in the emergence of some other weird aspect (which is often underplayed by the proponent of that interpretation); that's the law of conservation of weirdness.

As for Schrodinger's Cat, I don't see why we can't say "We cannot know the state of the cat until we look in the box", and NOT "The cat is both alive and dead, and the act of our looking at it causes it to become one way or the other" - which makes absolutely no sense.

See my other posts with regard to the poor beast.

Dragonfly: Are you saying that QM theorizing led to real technology that would not now exist save for that theorizing?

BTW: My four cats are not involved with this discussion. They don't want anything to do with QM.

--Brant

[Dragonfly]

Dragonfly: Are you saying that QM theorizing led to real technology that would not now exist save for that theorizing?

Certainly. All modern solid state electronics is an application of QM, as are lasers, MRI, electron microscopes, nuclear energy systems and atomic bombs. Without the theory these wouldn't exist, and I think you may classify those as real technology.

BTW: My four cats are not involved with this discussion. They don't want anything to do with QM.

Can't blame them. But not all physicists are like Schrödinger.

[bmacwilliam]

Not so fast... that a wavefunction is non-local is not the same as saying that an electron is a two places at the same time, that would be trying to reduce it to some kind of classical (even if rather weird) interpretation, the position of the electron is just not defined. And that the possibility of observation changes the outcome of an experiment indicates that the role of consciousness is a red herring.

Some "things" can travel faster than light. The idea of non-locality has been shown where particles "communicate" over large distances totally instantaneously.

Here you should also be careful with the interpretation of the EPR/Bell experiments, this is rather tricky stuff. But it is certain that it is not possible to use EPR correlations to transmit information faster than light, and the principle of special relativity is not violated.

Man, I'm rusty on this stuff and I gotta reread my old texts some day but I agree. The fundamental issue is that indeed you cannot apply anything "classical" to the concept of "where" the electron is or how it possibly interferes with itself.

If I remember correctly, a cause/effect relationship happens supraluminally (sp?) but information does not travel faster. However, I do think that there was a relativity violation here no? Damn, I gotta dust off those books!

Bob

[bmacwilliam]

I don't know QM, but I've heard that QM has been applied in real technology and that it "works" so I guess it's at least partially true. I wonder if the real problem is with how people explain it, the wording they use. I would love to encounter an Objectivist Physicist who could explain QM in a way that made sense, but then, at a microscopic scale sometimes common sense doesn't seem to apply.

I've only seen it explained "away" by Objectivists, using alternative theories (hidden variables usually) that makes absolutely no sense to me. This however doesn't mean that it doesn't actually make sense :-)

Bob

[John Dailey]

~ To paraphrase an old friend: "The cat's dead, Jim; 'dead', as we know it." - He would NOT add "...on the Other hand..."

~ What I'm surprised at, is why no one's empirically set up such an experiment (ok, with a malaria-carrying mosquito; even PETA might not hassle that one) with a camera-and-digital-recorder constantly monitoring (ie: recording, not 'observing') the box's internal dynamics, and whenever a particle is emitted, then a playback to and past that point is...observed. --- Or, have they and I missed hearing about it? Would the argument about the cat's being dead/alive apply to the recorder having recorded/not-recorded it?

~ I've heard of beating a dead horse, but god, this poor cat!

LLAP

J:D

P.S: Is everyone REALLY sure that the cat was really still in there after the box was closed? :devil: Considering some of the conflicting views, this presumption itself might be false.

[John Dailey]

~ A last quick thought on this unobservable cat-in-the-box: In Search of Schrodinger's Cat by John Gribbin is a good lay-person's intro to the whole subject.

~ Wiki has some good info on the contrary arguments also.

~ "He's dead, Jim"-vs-"IT'S ALIVE!" -- what a conundrum...before opening Cat-ora's Box.

LLAP

J:D

[Paul Mawdsley]

The big problem is that the results are sometimes so counterintuitive, but as all experiments confirm its predictions, the only logical conclusion is that reality itself is counterintuitive if we look closely enough.

Either this or our intuitions are counter reality. If our intuitions are counter reality, then we must change the principles on which our intuitions are based.

...that's the law of conservation of weirdness.

I burst out laughing when I read this. My 7 year old son walked into the room as I was laughing and asked what was so funny. How do you explain "the law of conservation of [quantum] weirdness" to a 7 year old? I've given myself until the weekend to work on that one.

Well, that's exactly the point, we can't sugarcoat the pill. Every attempt to give an interpretation that seems to take away some weird aspect, will result in the emergence of some other weird aspect (which is often underplayed by the proponent of that interpretation)

Man, am I stubborn! I can't put this thing down until I find an interpretation that untangles the paradoxes, takes away the weird aspects and does this without underplaying any of the evidence.

...I admit to being not well read about QM, but the more I read about it, the more I believe that the reality of the subatomic field (and macroscopic field) presents new principles, and new applications of old ones, that are not present at midrange where human beings exist.

I think it is a mistake to take a general principle like causality (which is so all-inclusive that it is almost meaningless when it is taken as a stand-alone principle), see how it works midrange, then try to force observed subatomic behavior into it. I see nothing wrong with noting that something always causes something else at a subatomic level.

The principles of reality work all the way down or they are not principles of reality. Is causality a principle of reality or not? Causality is all inclusive because it is a principle of reality. It is only meaningless if we have not discovered its meaning in reality. The concept of causality presented explicitly by Rand and Branden (until now Peikoff hasn't interested me enough to read his work) is the bare bones outline that states there is a necessary connection between identity and action. The principles that underlie real entities and real actions must be discovered via a process of observation, abstraction and induction. Without fleshing out what things actually are and how they actually behave, the concepts of identity and causality are virtually meaningless.

What causes what is the big question and I see nothing wrong with discovering such causality by the usual methods of speculation/hypothesis/theory and trial-and-error.

The point that is made in modern physics is that, if you can't observe, measure or quantify anything beyond the mathematical limit defined by Heisenberg's uncertainty principle, you have nothing to base "speculation/hypothesis/theory and trial-and-error" on. The only way to conceivably go beyond the quantum limit without flying off into pure fantasy is to clearly identify the principles of identity and causality that consistently govern all other observable entities and actions, and use these principles as a guide to shaping theoretical underlying variables that can explain why physics works as it does. This is the job of philosophy (although, not necessarily philosophers).

I don't know QM, but I've heard that QM has been applied in real technology and that it "works" so I guess it's at least partially true. I wonder if the real problem is with how people explain it, the wording they use. I would love to encounter an Objectivist Physicist who could explain QM in a way that made sense, but then, at a microscopic scale sometimes common sense doesn't seem to apply.

I've only seen it explained "away" by Objectivists, using alternative theories (hidden variables usually) that makes absolutely no sense to me. This however doesn't mean that it doesn't actually make sense :-)

Bob

Okay, let's have some fun. I want to take a shot at an interpretation of the double slit experiment that untangles the paradoxes, takes away the weird aspects and does this without underplaying any of the evidence. I want to give Dragonfly ample target to shoot at (which will give me more information to play with). I want to attempt an interpretation of the double slit experiment that uses the accepted language of modern physics without getting into any discussion of hidden variables (even though my thinking has taken me into an exploration of the possible nature of hidden variables).

I tend to prefer thinking of the double slit experiment in terms of electrons passing through the slits rather than photons because I get very hung up on how photons are described in modern physics. The "wavicle" idea just bugs me. I have no problem with everything having both wave and particle attributes. I don't think the popular image of a photon even comes close to reality. The image of an electron comes much closer in my mind.

If we were to imagine the double slit experiment as an isolated system, the only things we would need to consider are the electron emitter, the electron, the screen with 2 slits, the detector screen, and the geometry of space/time. How can we paint a non-paradoxical picture of quantum reality with a very local and causal description when we observe apparently non-local effects, that bring causality into doubt?

If we do not think about the effects the other elements might have on space/time geometry, we would expect the electron to follow the simple paths described by classical physics. We would see no interference fringes. But there is more to this system than just a particle, its momentum and its trajectory. The presence of the other elements of the system affect the geometry of space/time. Here, I am not talking about the gravitational effect of things on this geometry. I am talking about the electro-magnetic effect on this geometry. In particular, I am talking about the effect of the emitter's constituents on this geometry.

Not only is the electron emitter the point of origin of electron and its trajectory, it is the point of origin of oscillations in the EM field or in the geometry of space/time. The atoms that make up the emitter at the point of origin have a vibrational energy that is related to their temperature. This vibrational energy is transferred to the EM field and travels as a wave at the speed of light. Three things are very important to identify: the electron travels as a particle; the vibrational energy that radiates from the atoms in the emitter travels as a wave; and since both have the same point of origin, they are both intimately connected as part of a dynamic system.

Now, one thing we have discovered about EM waves, just like water waves and sound waves, they exert a measurable pressure, or force, that can move particles. If that pressure is radiated directly outward from its source (perpendicular to the wave front), there will be no observable effect on the particle that has the same origin. If, however, this same wave passes through the double slits, it creates the typical interference pattern we have all seen in highschool physics labs. The nodes in the interference pattern create subtle points of higher and lower pressure that affect the trajectory of the electron. The electron will tend to take the path that maximizes its degrees of freedom, or reduces potential energy. The result is quantum jumping into pressure troughs between points of high pressure and the fringing observed on the detector screen.

There is no need to assume strange physics with unmeasurable waves (as do some hidden variable theories). We just have to consider the effect regular EM waves from regular atoms would have in the system. We don't have to assume wave/particle dualism. There are particles and the geometry of space/time is waving. We don't have to assume non-local causation. We just have to swallow the idea of the geometry of space/time without questioning it too much. (If we question it too much we will be forced into considering hidden variables.)

The EPR/Bell experiments can also be interpreted from this perspective. Any 2 particles that have the same point of origin and the same speed but are moving in different directions would be connected by any wave that has the same point of origin. Any measurement of one of the particles will disturb the EM wave that connects it to its twin and will affect the outcome of the measurement of the twin even over vast distances. The collapse of an EM wave would be like the bursting of a balloon. It instantaneously changes the geometry of space/time by ceasing to exist.

Another point to mention is that a measurable prediction can be made from the above interpretation of the double slit experiment. The frequency of EM waves that come from the electron emitter would be determined by the temperature of the emitter. The measurable pressure produced by the wave should be reduced as the frequency goes down. If the double slit experiment were conducted by varying the temperature of the emitter, there should be a corresponding variation in the intensity of the fringes. Those fringes furthest away from the path predicted by classical physics should reduce in intensity as the temperature is reduced because the interference waves carry less energy, or pressure, to change the particle's trajectory. This would not be predicted by the current interpretation of QM. (Of course, the system would need to be isolated from other wave sources to control for extraneous variables.)

Paul

Edited February 9, 2007 by Paul Mawdsley

[bmacwilliam]

"The image of an electron comes much closer in my mind."

More later, but images of electrons cause me as much consternation as anything else. For example, an "orbiting" electron (the term orbit is not a good one because it doesn't really describe what's going on) has a probability distribution that is zero at the centre. In effect, the electron can travel from A to B without traversing a point in between. It doesn't go around it though, it travels through it, but without ever actually being there.

So the questions that arise because of this are numerous. Wave properties help to some extent. I can picture an electron as a 3-D standing wave with a node at the nucleus, but that's not good enough. Other properties are not explainable like this.

"If the double slit experiment were conducted by varying the temperature of the emitter, there should be a corresponding variation in the intensity of the fringes. Those fringes furthest away from the path predicted by classical physics should reduce in intensity as the temperature is reduced because the interference waves carry less energy, or pressure, to change the particle's trajectory."

Not sure about this. Doesn't the energy of the waves determine the geometry of the interference pattern, not the intensity? What I mean is I don't think it matters how energetic the individual emissions are with respect to pattern intensity.

Bob

Edited February 9, 2007 by Bob_Mac

[Dragonfly]

Not only is the electron emitter the point of origin of electron and its trajectory, it is the point of origin of oscillations in the EM field or in the geometry of space/time. The atoms that make up the emitter at the point of origin have a vibrational energy that is related to their temperature. This vibrational energy is transferred to the EM field and travels as a wave at the speed of light.

The photons ("EM-field") emitted by vibrating molecules have a wavelength that is many orders of magnitude larger than that of the electron, so they can't have any effect on the interference of electrons. Anyway, the wave-character of electrons has been established beyond any doubt, we use this feature for example in electron microscopes, which make much larger magnifications possible than with light microscopes as the wavelength of electrons is much smaller than that of visible light. Really, if you want to change the theory, you'll have to learn it first, especially if your version goes against that of thousands of the brightest minds who have worked on it for many decades. Speculation is fine, but speculating without any real knowledge of the field is worse than useless.

[Dragonfly]

Not sure about this. Doesn't the energy of the waves determine the geometry of the interference pattern, not the intensity?

That's correct. The interference pattern isn't dependent on the intensity of the beam, single photons or single electrons will give the same pattern as an intense beam of photons/electrons (it only takes longer). It's the energy of the particles that determines the wavelength and thereby the interference pattern.

[bmacwilliam]

Let me see if I get this right (at least in non-math lingo)- another way of looking at weirdness...

QM accurately predicts correlations (electron spins, and photon properties) that have been experimentally confirmed - lots of times.

These observations violate Bells Theorem which then I believe means that AT LEAST one of the following must be false:

1.) Locality (supraluminal connections between widely separated particles is not possible)

2.) Logic works

3.) Reality exists independent of observation

One or more of these must be wrong, not according to theory, but according to observation. And if I remember correctly, there's good arguments that they ALL might be wrong (or at least 2 out of three).

QM theory violates this, but so does REALITY and hence the deep problem. FWIW, logically Bell's Theorem is not that tough to understand, and violations truly make one think "What the *&@#^! is happening????"

Bob

Edited February 9, 2007 by Bob_Mac

[bmacwilliam]

Objectivist metaphysics is based in identity, not causality. There are any number of epistemological assumptions we take from the macroworld to the micro:

1. Separability of entities from their surrounding space.

2. Constancy of things like time, length and velocity.

3. The same event can't have two different outcomes.

I'll venture out on a limb and say that I think that all three have been experimentally violated - in one case more than a hundred years ago.

Bob

[Paul Mawdsley]

Really, if you want to change the theory, you'll have to learn it first, especially if your version goes against that of thousands of the brightest minds who have worked on it for many decades. Speculation is fine, but speculating without any real knowledge of the field is worse than useless.

That's the spirit!

I wasn't trying to go against "thousands of the brightest minds who have worked on [QM] for many decades." I was trying to incorporate what they have said into a perspective that does not require paradoxes, dualities and the giving up of our ability to visualize a causal reality. Many of those bright minds also had similar interests. Maybe if you didn't automatically assume my thinking is "worse than useless," you might try to understand what I was saying and find some value in it. While I respect the minds of the many physicists that have contributed to the emergence of the modern view, I think there is something physicists might gain from philosophy. Until philosophy and physics can find a common ground without one negating the evidence and rational integrations of the other, I don't think either can claim to have it all figured out. And maintaining a polemic between the two will definitely not improve things.

The photons ("EM-field") emitted by vibrating molecules have a wavelength that is many orders of magnitude larger than that of the electron, so they can't have any effect on the interference of electrons.

I wasn't talking about the electrons absorbing the energy from a photon. Of course, in such a case absorption must be quantized. I was talking about the geometry of space/time being distorted by the presence of EM waves. This distortion can be considered somewhat analogous to the distortion of geometry captured in general relativity. Where, in general relativity, mass causes a large scale distortion of geometry, I am suggesting that we can think of electro-magnetic phenomena in general, and EM waves in particular, as causing a small scale distortion of geometry. In such a case, quantum jumps could be considered the result of straight line motion in curved space/time on a micro scale. Since it is not the absorption of energy from the photon that causes the electron to change its trajectory, it doesn't matter that the "vibrating molecules have a wavelength that is many orders of magnitude larger than that of the electron." It is the effect these vibrating molecules and their associated EM waves have on geometry that causes the interference pattern of electrons on the detector screen.

Anyway, the wave-character of electrons has been established beyond any doubt, we use this feature for example in electron microscopes, which make much larger magnifications possible than with light microscopes as the wavelength of electrons is much smaller than that of visible light.

I never said the electron does not have measurable wave characteristics. In fact I said, "I have no problem with everything having both wave and particle attributes." I just don't think the particular wave characteristics of the electron itself is necessarily important for understanding the electron's behaviour in the double slit experiment. It is by assuming that it is the electron's own wave characteristics which cause the interference pattern that we run into the paradoxical thinking of the electron having quantum superpositions instead of trajectories. Causal theories of QM tend to look for the wave characteristics of the double slit experiment outside of the electron's own wave characteristics. My problem with causal theories of QM is that they ultimately rely on unmeasurable wave forms or some such thing. One thing you have shown me is that modern physics creates a self-consistent view of existence. My only problem is that it is incomplete because it requires we explain away certain realities such as volition and causality. I am just looking to create a causal theory of the double slit experiment that places the nature and source of the interference waves outside the electron but inside something readily observable and measurable such as the atoms of the emitter. If this were possible it would be one step toward bringing physics and philosophy together by maintaining, once again, that all actions are causally necessitated.

Paul

[Paul Mawdsley]

Objectivist metaphysics is based in identity, not causality. There are any number of epistemological assumptions we take from the macroworld to the micro:

Causality is a corollary of identity. You can't have one without the other just as you can't have some thing without it behaving in some way. Causality is the necessary connection between what the thing is and what it does. Objectivist metaphysics has to be based on both.

1. Separability of entities from their surrounding space.

This is the particle aspect of entities. That a thing also has a wave character does not violate this. However, it may mean Objectivism needs to expand its metaphysics, epistemology, ethics, etc. to include the interconnectedness of existence, including social existence. But then would it be Objectivism?

2. Constancy of things like time, length and velocity.

That our measure of time, length and velocity is relative to our motion does not mean that we cannot conceive of an absolute reality, nor of these being an expression of an absolute identity. It just means we have to conceive of these absolutes by wearing the philosopher's hat rather than the physicist's. The physicist is restricted by what he can measure and quantify. The philosopher is not.

3. The same event can't have two different outcomes.

To what scales are we willing to measure two events the same? From a philosophical point of view, there is no problem to suppose the existence of hidden variables at micro scales. From a macro perspective, the whole universe could be considered a system with no event occurring in isolation. Can it ever be said to be the case that all elements of this system are identical in two separate events?

[James Heaps-Nelson]

I should have said Objectivism does not specify a requirement for causality other than a preference for an entity-action framework in most cases. We have to ascertain the causality by looking at things. If things act funny, we have to incorporate that in our causality model.

Jim