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Quantum Reality: Beyond the New Physics (1987)

door Nick Herbert

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This clearly explained layman's introduction to quantum physics is an accessible excursion into metaphysics and the meaning of reality.nbsp;nbsp;Herbert exposes the quantum world and the scientific and philosophical controversy about its interpretation.
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“A gravity wave is a ripple in the curvature of space-time. Einstein’s general theory of relativity predicts that gravity waves ought to be generated wherever huge masses accelerate - for instance, in binary star systems. If Einstein is right, gravity waves from all parts of the sky pass through the Earth every day. A gravity wave slightly warps every object in its path, squeezing it in one direction and stretching it in the orthogonal direction. Because of the ubiquity of gravity waves, every object we see is continually pulsing to the gravitational rhythm of distant stars.”

In “Quantum Reality” by Nick Herbert

“Bell’s theorem has immensely clarified the quantum reality question. For instance we now know for certain that no local model can explain quantum facts. Bell’s theorem has important consequences for all models of quantum reality including the Copenhagen Interpretation, and its effects continue to reverberate in physics circles.”

In “Quantum Reality” by Nick Herbert

“It’s beginning to look as if everything is made of one substance - call it ‘quantumstuff’ - which combines particles and wave at once in a peculiar quantum style all its own.”

In “Quantum Reality” by Nick Herbert

“The manner in which an electron acquires and possesses its dynamic attributes [e.g., ‘position’; to distinguish them from the ‘static’ attributes mass, charge, and spin] is the subject of the quantum reality question. The fact of the matter is that nobody really knows these days how an electron, or any other quantum entity [or ‘quon’ by using Nick Herbert’s coinage], actually possesses its dynamic attributes.”

In “Quantum Reality” by Nick Herbert

“In its most up-to-date version Bell’s theorem reads: ‘The quantum facts plus a bit of arithmetic require that reality be non-local. In a local reality, influences cannot travel faster than light. Bell’s theorem says that in any reality of this sort, information does not around fast enough to explain the quantum facts: reality must be non-local.[...] Bohm’s model is an example of such a world. In this model an invisible field informs the electron of environmental changes with a superluminal response time. [...] Bell’s theorem proves that any model of reality, whether ordinary or contextual, must be connected by influences which do not respect the optical speed limit. If Bell’s theorem is valid, we live in a superluminal reality. Bell’s discovery of the necessary non-locality of deep reality is the most important achievement in reality research since the invention of quantum theory.”

In “Quantum Reality” by Nick Herbert

“Thus Eberhard’s proof [of no-communication between quantum entities] permits nature to send perfectly encrypted messages along FTL channels but denies humans access to such channels so long as their actions are bound by the rules of quantum theory. [...] Skeptical scientists [and SF authors] compare the attempt to construct real superluminal communicators based on strong quantum correlations in the face of Eberhard’s impossibility proof with attempts which flourished in the last century to devise perpetual motion machines in the face of the law of energy conservation.”

In “Quantum Reality” by Nick Herbert

In 2015 gravitational waves were “observed by the LIGO consortium.” It was a only a question of time but it took physicists 30 years since Nick’s book...

I first read this book in high-school when it came out. I didn’t understand much of it back then. For a few months I’ve been binge reading my way through Quantum Mechanics books, and I wanted to see whether Nick’s vision still held up after so many eons. Nick’s ability to give us a vision of Quantum Reality is still like no other. Nick’s take on Bohmian Mechanics was the first one I read that seemed to make some sort of sense. Pilot-wave theory is Bohmian mechanics. De Broglie realized pilot-wave theory was incorrect and went back to his original double solution theory. To refer to pilot-wave theory in order to refute de Broglie is not only misleading, it is incorrect, since de Broglie himself realized pilot-wave theory to be incorrect. In de Broglie's double solution theory there are two waves. There is the wave-function wave which is statistical, non-physical and is used to determine the probabilistic results of experiments. There is also a physical wave in the chaotic sub-quantic medium which guides the particle. Today, the chaotic sub-quantic medium is the chaotic super-solid dark matter. There is evidence of the super-solid dark matter every time a double-slit experiment is performed as it is the super-solid dark matter that waves. Wave-particle duality is a moving particle and its associated wave in the super-solid dark matter. In a double slit experiment the particle always travels through a single slit and the associated wave in the super-solid dark matter passes through both. As the wave exits the slits it creates wave interference which alters the direction the particle travels as it exits a single slit. Over time the particles form an interference pattern. Strongly detecting the particle exiting a single slit destroys the cohesion between the particle and its associated wave, the particle continues on the trajectory it was traveling and does not form an interference pattern. It is the chaotic nature of the super-solid dark matter which causes the Casimir effect which Nick does not use as experiment.

Re-reading this now I got the impression Nick seems to be a proponent of deBroglie.Bohmian Mechanics. I never thought the weird wave-particle mashup of dBB could work out. It has other problems, such as needing a relativity-violating preferred frame or foliation to handle strong correlations. The strong correlations might be too much for even FTL signalling to handle, if complications like intervening wave plates are in place. Also, Copenhagen does have a core thesis: fully identical starting conditions can lead to various results. Deterministic dBB however, implies that identical starts lead to singular identical results. Various initial distributions might typically develop to expected multiple outcomes, but shouldn't we expect some convergence toward repetitive outcomes as initial preparations become more fully alike? Put aside basic atomic physics for a minute. Can dBB handle muon decay, Delayed-Choice-Experiments, K-electron capture, intrinsically (?) ambiguous number of photons in QFT or as reflected from accelerating mirrors, or Hawking radiation? Can it gracefully handle the banality of a photon or electron deciding whether to take a right-angle turn at a partially-reflecting mirror? This expands to the general problem of speeding tiny nuggets banging into microscale structure. One strange irony: pilot waves "guiding" particles is reminiscent of the criticism that mental influences break conservation laws. Still, dBB and proposals like GRW deserve credit for their less-shaky arguments although I don’t believe in them. Nick’s surreality shouldn't be surprising to me though, considering lots of physicists nowadays still apparently believe in the completely unphysical Copenhagen interpretation. Although I'm mystified at their skepticism about non-locality considering Copenhagen is itself non-local. Of course, “anyone-who-knows-anything-about-QM” knows that "non-locality" in this context does not refer to FTL signalling. Nick even writes about supra-luminal “communication” and I have lot’s of problems with this..

I’ve seen being bandied about that “non-locality is unavoidable in any interpretation". Simply not true. What they mean is "non-local realism" which is an entirely another beast. What we know is that the universe can't be local AND realist at the same time...and not even that, given the possibility of a super-deterministic scenario, as Bell himself admitted. Unfortunately Pilot Wave theory does have some problems of its own and adds some unneeded complexity to the interpretation of quantum mechanics which goes against the principal of Occam's razor. John Bell and Von Neumann have given Pilot Waves a lot of evidence to overcome as they completely dismiss the idea of a hidden variable theory or at the very least that hidden variable theories do not have any sense of locality to them which is yet another problem since local properties are common property to exploit in the mathematics of physics. Any type of pilot wave theory is a hidden variable theory which is something that sits very uncomfortably with many mainstream physicists. Especially since due to Heisenberg there is no way to ever measure the hidden variables that this type of pilot wave theory would need to make its deterministic predictions and then yet again we run into Occam's Razor. Also invoking spooky action at a distance is a very strong thing to invoke. Quantum Field Theory and others have attempted and succeeded to remove this idea from the theory. Now Entanglement does seem spooky, but what are the underlying principals of Entanglement and could they be explained with modifications to our current theories rather than invoking spooky action at a distance. Even though many physicists are OK with this idea, I am not and spooky action at a distance is equivalent at least in my mind to having no explanation at all. Bohr was at least honest when he said he has no explanation for that mechanism. Bohm seems to invoke more spooky stuff which makes this stuff more mysterious than it should be. The universe doesn't have to be deterministic either. There is no law in physics that states that the universe must be deterministic. If it did pilot wave theory would definitely be a shoe in. However the universe doesn't seem to be deterministic at all at least on the scales of the size of atoms and smaller. This isn't to say that I like the interpretations of quantum mechanics myself. As a matter of fact I don't like them at all. However the Copenhagen is more feasible or at the very least present fewer problems for physics as a whole. The Copenhagen one goes a little further by not even attempting to touch the subject of how it works but rather to just give us a way to predict this quantum weirdness (“Shut-up-and-Calculate”). Philosophy really shouldn't be a consideration here as we could all be brains in jars for all we know but that does nothing to help us with solving this problem.

Now I'm more interested in determining what the wave function actually is and then perhaps we can garner some insight into what the wave function is even describing. The wave function is inherently a complex function and that poses many problems in interpreting it as we don't know what to do with it other than square it to get a probability amplitude which is just fine for making a measurement or doing a calculation, or making a prediction but it tells us nothing about the nature of the wave function itself. What do the complex number in this function even mean? What is the real world analog for a complex or imaginary number? How can we use the behaviours of real waves to potentially find out this information about complex waves? These are all really hard questions to answer and perhaps they have no easy or obvious or comfortable answers but those answers will help guide us to a better interpretation of quantum mechanics.

I can see a way out of this conundrum for dBB. dBB uses its Guiding Equation to describe something that Copenhagen dismisses as random: the actual location of the particle in question. That location is what is referred as the "hidden variable" of Bohmian Mechanics. What dBB makes explicit is that this location is not a local function of a particular particle - it is a global property of the inherently non-local wave function itself. And it MUST be non-local, since the wave function manifests NOT in physical 3D space, but in complex-valued configuration space. PWT uses its Guiding Equation to describe something that Copenhagen dismisses as random: the actual location of the particle in question. That location is what is referred as the "hidden variable" of Bohmian Mechanics. What BM makes explicit is that this location is not a local function of a particular particle - it is a global property of the inherently non-local wave function itself. And it MUST be non-local, since the wave function manifests NOT in physical 3D space, but in complex-valued configuration space. That is also the answer to your questions about the interpretation of the complex nature of the wave function. All things we can directly observe in 3D space must be real-valued solutions of the wave function. For example, the probability density function, which squares wave function complex coefficients, a mathematical operation that can only produce positive real numbers. But behind the scenes is the tricky part that the complex nature of the wave function explains. Real-world probabilities are positive numbers from 0-100%. But in the double-slit experiment we see wave interference effects that mutually cancel out, resulting in near-zero probability of finding a particle in certain locations. How can these positive-valued probabilities negate each other? The answer might lie in the complex-valued probability amplitudes of the wave function. In configuration space, these amplitudes are not exclusively positive-valued, they range over negative and imaginary coordinates as well. When probability amplitudes from overlapping waves are combined, they can and do cancel out, a straightforward result of complex mathematics. It is that result that is squared to produce the positive-valued probability density function, which in physical 3D space always ranges from 0-100%.

I can see some people in the back of he room wanting to ask a few questions. Here they’re with my answers:

1. “Is there an interpretation of the measurement problem in the double slit experiment in pilot wave theory? As in, what's the equivalent to Copenhagen's "collapse of the wave function"? If the pilot wave is considered a physical entity, why does measurement/decoherence suppress the interference pattern?” Answer: According to Bohmian Mechanics, each time a measurement is made, the wave function of the measuring device becomes entangled with the wave function of the measured particle. That mutual entanglement is what Copenhagen refers to as the "collapse" of the measured particle's wave function. (But note how Copenhagen excludes the measuring device, thus creating its notorious self-inflicted "measurement problem".) The Pilot Wave is NOT a "physical entity" manifested in 4D spacetime, it propagates non-locally in complex-valued Configuration Space (the domain where the quantum wave function is defined). If it manifested in 4D spacetime, the Pilot Wave would become a local phenomenon subject to relativistic propagation effects, contradicting the non-local nature of Bohmian Mechanics;
2. “How does this interpretation account for the disappearance of the interference pattern when the slit the photon went through is detected?” Answer: The photon always goes through one slit, but when you have two slits available the WAVE can go through both and affect the photon accordingly. Closing a slit blocks off the wave and changes how the photon is affected;
3. (follows from 2). “Yes, but what i mean is, when a detector is placed to definitively determine which slit a photon passes through, the interference pattern disappears. And further, if a scrambler is placed down the line to prevent that measurement, the interference pattern emerges, even though no modification was made where the photon travels. I'm not talking about closing a slit.” Answer: The pilot wave guides the particle. The wave however is always affected by both slits just like any other wave would. So if you're placing detectors to try and detect the particle, you will in fact affect the wave passing through the slits. Since the wave guides the particle, the particles path is also altered. In that case, it results in the particle going through only one slit, since the detector (in a sense) is blocking off that path for the wave. This also explains 'weak measurement' in that if you place a detector so that you still can't tell where the particle is at but can narrow it some, the pattern begins to change. Pilot wave theory interprets that as interfering with the pilot wave to a lesser extent. Copenhagen interprets this as collapsing part of the wave function in that only part of the possible states is excluded from the possible outcome. If you are not familiar with waves there is quite a lot of literature or you can do the same setup as I did a long time ago (with oil) and observe the "particles" and the behaviour on macro scale. For all intents and purposes it's pretty accurate representation of what is going on on subatomic scale but it's incredibly slowed down and scaled up. if you do enough runs you can even compare that it really corresponds with the odds you get with the classical "quantum" statistical equations but you can see how each particle arrives and what influences the movement and how. The double slit experiment is great way how to spend afternoon (or a week). I have studied quantum physics, but pilot wave theory are among the most advanced thing you can find in the field. So I can only say there is an explanation to the quantum eraser with the pilot waves theory, it has to do with hidden variables, but anything deeper than that, I'm not gonna dive into a book about pilot waves theory to answer that. The problem is that this theory is being discuss among the smartest and knowledgeable scientists on earth, and they've yet to reach an agreement themselves, so I'm not gonna even try to argue about if it's right or not. So either you dive into the study yourself or you should just take it as a scientific news like me;
4. “Can dBB account for all or more experiments than previous established theories?” Answer: Yes it can. It's basically just a mathematical transformation of the traditional quantum mechanics. Writing equations in a new form. So everything Copenhagen interpretation predicts, BM can reproduce with the same result. For your original question, the answer is the collapse of the wavefunction, same in both theories, only in BM there is more "explanation" on the cause of the collapse so collapse is no longer a basic hypothesis (In Copenhagen interpretation it's simply observation causes collapse and that's an axiom so no more questions asked. While in BM its the observer's wavefunction and the system's wavefunction cannot be decoupled and they as a whole evolve according to the Schrodinger Equation, so if you only look at a part of the wavefunction which is the observed system it behaves as if it collapses. In fact, strictly speaking, in dBB the whole universe wavefunction evolves as a whole which never collapse, and cannot be taken apart. But for a system that's independent enough, with nobody looking at it, the factorization of the wavefunction makes it look like the system itself evolves according to the Schrodinger Equation, like a little universe of itself.) Experimental physicists even performed a second experiment after the original double slit experiment called the delayed choice quantum eraser experiment which showed that even with a detector as long as the path information is impossible to know it acts as a wave but if they knew the path information then the result provided a pattern of 2 bands and not an interference pattern a wave would produce. From that you basically see that the detector is not a factor in the wave turning into a particle and vice-versa;
5. “Could the vibrating oil analogy also describe how Pilot Wave Theory works with Quantum Field Theory? The surface of the oil is the quantum field, and the droplets bouncing on top of it are the particles that emerge from the field. Or am I misunderstanding something?” Answer: No. Quantum field theory has pretty much declared any pilot wave interpretation dead. Photons, for instance, don't even have a wavefunction, and cannot be talked about as having any definite position at all (this also kills many worlds interpretations, by the way). The correct picture is one where particles can be created and destroyed all the time -- but when I say "particle" I should really say "wave". Quantum field theoretical particles are wavelike in all aspects except for the fact that they come in discrete units. So one unit of light of wavelength 530 nm, two units of light of wavelength 435 nm... these "units", though they look and behave in all aspects just like plane waves, we call "photons".
6. “Relativity proves that all reference frames are equivalently valid from the observer's perspective at speeds less than the speed of light. It's math breaks down at speeds greater than c. Relativity says NOTHING about speeds greater than c and it certainly does not prove faster than light travel causes causation or backwards time travel problems. Using the principle of relativity at speeds greater than c is far outside of the scope of relativity and anything ever tested. Just try doing the math for it. Your statement is the equivalent of being a fish and forming laws about how fish swim underwater then trying to use those same principles to explain that nothing can fly in air. Forcing a theory to uphold a principle thought up by humans in a realm outside of any experiment ever done on that principle is arrogant and unwarranted. We simply do not know. Also we can't distinguish between reference frames meaning we can't find a universal clock. However, relativity never proved there was no such thing. In fact relativity allows an observer to prefer their own reference frame over all others. There is no reason nature can't have a single reference frame all FTL effects occur on (or actually what physicists call a foliation). This would not violate relativity in any experiment we've ever thought of because there would still be no way to distinguish between reference frames at speeds less than c. It does violate the principle of relativity which is why it's said that pilot wave theory violates relativity. HOWEVER, you can violate a principle of nature in a theory no matter how well experimented on as long as this violation is outside of the domain of all experiments. The speed of light is a very special boundary so it may be a boundary where the laws of physics change. Perhaps all particles including light move at speeds v ( )
  antao | Oct 16, 2019 |
This book is really comprehensive towards the most commonly accepted ontologies, and goes over several of the major quantum oddities (the measurement problem, nonlocality, etc.) and gives the standard response from each ontology.

The term "quantumstuff" is really a solid way to talk to non-physicists about wave-particle duality, and I found the detail given to the neorealist perspective refreshing. ( )
  cartomancer | Sep 5, 2013 |
ספר מרתק על הניסיונות השונים, שמונה במספרף לתאר את המציאות שמאחורי תורת הקוונטים. החל מגרסת קופנהאגן (אין מציאות) דרך אינשטיין והריאליסטים (מציאות רגילה, חסרים משתנים) וכלה בעולמות מקבילים.
דגש רב (מדי?) על משפט בל שטוען לקיום קשרים מהירים ממהירות האור ולא לוקליים.
קריאת הספר רק הגבירה את הרגשתי עד כמה אינני יודע. ( )
  amoskovacs | Dec 11, 2011 |
This is a great book by Nick Herbert. This is a book that deals with the interpretation of Quantum Physics. But its importance is that it deals not with a 'spiritual' or 'mystical' understanding of quantum physics but with how scientists and physicists themselves interpret quantum physics. It is a book of pure science and there is no quantum mysticism involved here.

Nick Lembert discusses basically eight different interpretations of quantum physics. These include the Copenhagen interpretation, Feynman's interpretation, the 'multiple worlds' interpretation, etc. All these interpretations are the work of the greatest physicists in quantum physics. These are the ways in which the scientists understand how physics work. They are not important in getting the results of quantum dynamics, the maths of quantum physics works independently of which interpretation we may choose to believe.

And this is where Herbert shows the craziness of quantum physics: although all these interpretations are radically different from each other, they can all explain quantum physics equally well. Neither we, the non-physicists, nor the greatest physicists in the world, really know what actually is going on in this strange little world, whether the particles are behaving according to the Copehnhagen interpretation, the multiple world explanation, etc. Herbert handles this very well, we get a sense of why Feynman said, 'just shut up and calculate'. Scientists dont understand the basic reality of quantum physics either!

Another very useful thing I took away from the book was the explanation of the wave equations of Quantum Physics. Herbert does a fine job of showing what exactly waves are and how physics describes the particles as waves and what this means. This again shows up the mysteriousness of Quantum Physics in another way.

All in all, I would call this a very important book to understand the general principles of quantum physics, one that is vital because it sets out the different interpretations in a very clear and comprehensible manner. ( )
  PJMazumdar | Jul 15, 2010 |
Great exposition of quantum mechanics. The most memorable for me was his telling of all the different types of waveshapes that can be considered as representations. He used the analogy of a synthesizer to great effect. ( )
  br77rino | Apr 10, 2010 |
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This clearly explained layman's introduction to quantum physics is an accessible excursion into metaphysics and the meaning of reality.nbsp;nbsp;Herbert exposes the quantum world and the scientific and philosophical controversy about its interpretation.

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