The anti-Bohm antagonists clearly still resent Bell's advocacy of non-local hidden variable theories. Evidently they weren't content to shut up and calculate.
The collapse of the wave function is likely to be a nonlinear process requiring computer simulation. Any such simulation *must* make use of a random number generator. However modification of the very accurate Schroedinger equation is prohibited. There are two ways to resolve these apparently contradictory requirements. The first is to note that we need a nonlocal theory according to John Bell. Play around with the Minkowski formalism, and it will be seen that there are two ways to travel faster than light. I propose that the Schroedinger equation described an oscillation in one of the ways, and we can have orthogonal tachyonic Brownian motion in the other way. TBM comes into action during the nonlinear interaction between the wave function and the electromagnetic field, and a computer simulation which uses it will not have an issue with Schroedinger’s cat. Suppose we program a good quality simulation of the interaction between an alpha particle and two molecules of nitrogen trifluoride. There will be a time reversal button which enables us to retrace the simulation back to the start. Normal behaviour of this system is isentropic. Now use the same code with two molecules of nitrogen tri-iodide. Something radical can happen for which we need a new ingredient to get the destruction of unitarity and the big rise in specific entropy that can be expected. That ingredient is TBM. I suggest that two molecules of tri-iodide is the simplest possible detector. Someone might find something a bit simpler, but it won’t affect the argument. Our simulation will need to run in at least twenty four dimensions of configuration space just counting the atoms of the two molecules. This is more than my desktop computer can handle. The second way to resolve the conflicting requirements is just to throw away the Schroedinger equation for all objects heavier than the Planck mass. The replacement theory is classical dynamics plus a bit of ordinary Brownian motion on the same scale as the quantum mechanical Uncertainty Principle. This is a handwaving argument of course, but there is at least an aetiology of tachyonic Brownian motion to appeal to. I don’t think TBM itself has any aetiology. If we have an electron in a potential well, then the electron is modelled by the Dirac equation plus tachyonic Brownian motion. The well is considered to be a dimple in a heavy object, so it has a bit of classical BM which is much more disruptive than TBM. The well can deliver on the collapse of the wave function. Correlated TBM in the wave function and the electromagnetic field can deliver on Bell’s over-correlation, like a natural Vernam cipher. So I have a hypothesis on how to solve the measurement problem in a computer simulation. We will just have to see if it can be made to work. Any computer simulation I produce will be very much in the public domain so other people can have a go with other ideas.
OMG. I only have two years of college physics, but I feel like I’m understanding this better than some of the guys in the audience asking questions. Who are these people? 1:03:47
Funny. I’ve listened two or three lectures now on Bell, and up until seeing it written out on the slide 15:12 . I though they had been talking about ‘vehicles’ not ‘beables’ Vehicles made sense to me because they were things that could carry an observation to an observable. Beables is an awful term.
58:50 This is the most serious issue about pilot wave theories. In the real world there's no preferred reference frame and all observations vindicate Relativity. Some people are trying to fix the problems with Bohmian mechanics by going back to pre-Einsteinian aether ( Fitzgerald, Lorentz , Larmor) but this won't work, for the simple reason ( among others..) that in that case one cannot explain kinematically the usual, well confirmed relativistic effects ( time dilation etc).
@@DjamilLakhdar-Hamina Because Bohmian mechanics postulates an invisible ghost field that somehow knows what experiment you are carrying out. In return it gives you nothing that you can't do much easier without the ghost. ;-)
It looks like most people here are more interested in the presentation style than the substance. Not that there was any substance. Bohmian mechanics is bullshit. ;-)
@@benli5777 I did. It does exactly the same as Copenhagen, except that it sends you five times around the block and once into the department for supernatural phenomena to fetch a mysterious and unmeasurable guide field. ;-)
Great job as always Dr Maudlin. As a side note, it's amazing how people insist on supplying justification for people saying that some people just don't listen...I guess it's full employment for Dr Maudlin though. Does the questioner ruffled by tachyons not understand that the goal is to produce a theory with an ontological description that correlates with reality, not just a tool for predicting experimental outcomes. Who cares that non-relativistic quantum mechanics explains the data by assigning no propagation speed. Is the gravitational force communicated instantaneously? How about the electromagnetic force? So we can go back to Newtonian gravitational theory? If not, then what characteristics of a particle aside from being massless and chargeless allows particles at the quantum level to travel faster than photons? If there are no restrictions on propagation, then why do photons have a constant finite speed? The point is, the questioner seems unconcerned by describing our shared reality using theories that contradict each other. The whole point is to avoid this embarrassment.
I don't know about you guys, but standard quantum mechanics doesn't have observers, either. It has reversible and irreversible energy transfers, though. ;-)
Bell's postulate resembles a human being and the cells he is made of. "Macroscopic objects are made of local beables at microscopic scale." If beable is the property of being an individual, then Bohr position is not bizarre at all. My pencil is not the sum of the molecules contained in it. My pencil has the individuality of being my pencil. Silly is my example, but coherent and in agreement with Bohr. As a mathematical beable, the open set (0<x<1) is not composed of uncountable beables. It has properties, measurable properties, different from those of its component beables, whatever they might be.
Seen beable as the property of individuality, helped me understand Bell's program. A photon is a beable, so is the electron it surrounds. I am a beable.
ONE-INFINITY Singularity Apature of entangled wave-packaging formation is the simplest way to recognise Euler's e-Pi-i infinitesimal relative-timing by holographic AM-FM relative-timing modulation shaping, and all wave cause-effect is totally interpenetrating at this CentreofLogarithmicTime, projection-drawing Communication = . dt axial-tangential zero-infinity Entanglement limit. Looking through the Observer's nothing in No-thing vertex "hole in Time" vortex of fractal point-line-circle conic-cyclonic coherence-cohesion i-reflection, instantaneous reference-framing of transverse trancendental Pi-bifurcation containment.
33:50 - Wait a minute - how can the wave function have any impact on the beables? You don't GET anything tangible from the wave function without applying an observable operator. If beables are functions of the wave function, then there *is* a way to observe aspects of the wave function without going through the usual process and, one would presume, without collapsing it.
The Wave Function is the only thing that exists in Quantum Theory. Nothing else even exists. The Born Rule is something introduced externally to explain experiments but it is an ad-hoc addition that has no relation to the basic principles.
I think it is so impressive how experimentalists can find ways to solve problems and increase efficiency, making their measurements dramatically more revealing. Combining ions and electrons in one experiment, having two entangled pairs, and making practical use of quantum state teleportation, entangling ions, and even choosing R/L circular polarization are all facets of this team's amazing inventiveness.
With respect to quantum mechanics, it's mostly explained by the Schrödinger equation, yes, but that explanation is just a relationship between variables, it doesn't tell us what nature is made of, and how it works, in the atomic regime. To really understand nature, which is the mission of physics, requires interpretations of that equation. Bohr's Copenhagen interpretation embodies surprising mysticism in its axioms. This gives it a baggage that prevents easy understanding, as Merwin and Feynman famously pointed out. That is why discovering the Bohm interpretation is so important to physics students and to physicists: it reveals that nature in the tiniest scale is just as deterministic as our familiar classical physics. The only difference is that in the tiny scale, the nonlocality of nature is a major effect. Properties are not just confined to a single particle in tiny scale, but they potentially include all of the space around the particle, with no "inverse-square" falloff of influence. That is a BIG difference, and accounts for all the strange experimental results in quantum mechanics.
@@lepidoptera9337 I never said I didn't understand the accepted standard interpretation of QM. I said it is unnecessarily mystical. It caused Dr. Feynman, Nobel prize winner, to say that nobody understands QM. David Bohm's explanations are clear and understandable.
@@david203 There is nothing mystical about Copenhagen, you just didn't think about it carefully enough. And, yes, Feynman made a poor joke about superposition that everybody who doesn't want to study quantum mechanics in detail uses as a free get out of jail card for their intellectual laziness. ;-)
Honestly, I couldn't follow all the notation. It would be nice to have a more intuitive explanation of weak measurement, since it is such an important and valuable experimental technique. Here is what I understand: given a double-slit experiment with single particle traversals, we are interested in tracing back the expected values of the particle positions from their endpoints on the screen, all the way back to each slit, which are considered the particle sources, where each particle has a unique position with respect to one edge of the slit. Apparently, we do this through some sort of statistical average of an estimate of the particle velocity at each point from slit to screen, and repeat to generate the full Bohm family of trajectories. But I have no idea how the position or velocity of a particle can be measured weakly, that is, without destroying the particle or disturbing its measured position or velocity. I can imagine measuring its magnetic field (works for electrons but not for photons or neutral atoms) from a distance, but that is just a guess. I can't tell from the mathematics what is actually happening in a weak measurement. I see all the talk about the hyperbolic cosecant as irrelevant, since that is just a technique to take wide-ranging data and squeeze it down to one of two alternatives (in this case, one of two eigenvalues). It says nothing about how the data are measured without being disturbed by the measurement. The presentation at ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-ZUTF-R6xt2o.html is a bit helpful, in talking a bit more clearly about pre and post- selected states, but not by much. It seems that we first measure spin in the x direction, then in the 45° direction, then in the y direction and take the inner product of the three measurements, then normalize to correct for the larger amplitude of the 45° measurement. Did I get that right? I doubt it. I don't see how this disturbs the particle less. Even more helpful is the presentation by Aharonov himself, at ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-lcrGVf1L7L4.html . Here the explanation is much clearer, and we can see that the comparison between epsilon (the strength of the measurement) and epsilon squared explains why the measurement doesn't disturb the particles when epsilon is small, yet gives just enough information over a whole ensemble to produce a reliable result.
I didn't understand the whole animation thing, where a conditional wave function was illustrated, along with wave function collapse. I thought that in Bohm theory the great thing was that the universe includes the experiment AND the pointer device, so there IS NO environment. This means that there IS NO wave function collapse at any time. The pointer moves as part of the experiment, and shows the result without any decoherence. No?
That's right, the overall wave function always evolves according to the Schrödinger equation. But when you want to focus your attention on a subsystem only, you can define a wavefunction for it as shown. And right at 34:33 you can see how a collapse of this subsystem wavefunction comes about, not via a separate postulate like in standard QM but as a part of the overall dynamics. One of the humps of the subsystem wavefunction gradually vanishes because the horizontal green line does not cut the right blue blob of the overall wavefunction anymore.
At 28:24 Albert says that we can have no empirical way of using Bohm's particle trajectories. But this is only currently true, when electrons, photons, and atoms are generated in beams with only the crudest of (statistical) positions in spacetime. Certainly we will soon be able to manipulate single electrons and single photons, in which case the experimental results validating Bohm's deterministic trajectories will have eminent practical application. Imagine being able to aim a single electron at a silicon target and knowing for sure what effect it will have on the doping of a tiny area of the target, based on knowing the quantum guiding force and the exact initial position of the particle. We won't be limited to statistical patterns (distributions), but we'll be able to correct the aiming of the particle (with variable but known precision) to account for the device geometry by knowing its wave function.
Okay. I have to say: yes, we seem to make only local measurements in QM experiments, and infer QM nonlocality using them, granted. But why does that enforce the creation of two types of beables in the new theory, local and nonlocal? Why can't Bohm's idea that all wavefunctions are subsets of the Universe's wavefunction, specifically that the experiment must include the measuring device in its wave function, be joined by the idea that all beables are nonlocal? Yes, in practical terms one might measure a nonlocal beable locally, but why did Maudlin not propose that beables only be of one type: nonlocal? I don't get it.
Why is the uncertainty principle often presented as part of quantum mechanics, when it is entirely a classical law? So long as time exists and is relevant to experiments, the position of a particle and its momentum or energy are going to be dependent on each other simply because of the way they are defined! Specifically, speed is the derivative of position with respect to time. That is its classical AND quantum definition! Dependency on each other means that there could be a lower bound on the accuracy of knowing/measuring both at the same time. Jean-Baptiste Joseph Fourier showed that measurements in the time and frequency domains are always going to have a kind of reciprocal precision: you only need one measurement to determine position in time, but you need multiple measurements to determine speed in time. It is that simple. So, no matter what position or frequency/momentum values you choose, the error of their product will have a lower bound, right? But that's just the Heisenberg uncertainty principle. It has nothing to do with quantum mechanics, just the simultaneous measurement of two dependent functions.
The Heisenberg uncertainty principle is not a classical law, despite of Fourier's findings. Classical theories always attribute precise/single theoretical numerical values for ANY observable to ANY physical system (leaving thermodynamical systems aside) at ANY time. This includes observables like position and momentum. This attribution is done independently from any real measurement of observables. Additionally, classical theories themselves do not put any fundamental limitations on the precision obtainable by a real measurement of observables. Hence, you don't have a Heisenberg uncertainty principle in classical theories. One reason why you actually won't get arbitrary precision by real measurements even in a classical description, is due to uncountable many uncontrollable environmental disturbances during a measurement. Another reason why you never could get arbitrary precision by real measurements, even if you could control all of the environmental disturbances, is because classical theories are actually not capable of fully describing physical reality. Quantum theories attribute precise/single theoretical numerical values for A given observable to physical systems only in very exceptional circumstances, namely in case of physical systems that are in an eigenstate of the operator corresponding to that observable. In all other cases (the overwhelming majority of non-eigenstates), quantum theories attribute theoretical distributions of numerical values for that observable. Again, this attribution is done independently from any real measurement of observables. In case of eigenstates, quantum theories themselves do not put any fundamental limitation on the precision obtainable by a real measurement of the observable. In case of non-eigenstates, quantum theories however put a fundamental limitation on the obtainable precision, because they do not attribute a single numerical value for that observable in the first place, but already a whole distribution of values. Most physical systems are in a state, that is simultaneously a non-eigenstate of the operator corresponding to the observable for position and a non-eigenstate of the operator corresponding to the observable for momentum. For these states, quantum theories simultaneously attribute a theoretical distribution of position values and a theoretical distribution of momentum values. Again, this attribution is done independently from any real measurement. Heisenberg's uncertainty principle now states, that the product of the width of these two theoretical distributions is always bigger than a global nonzero constant. This is a pure quantum mechanical result that you don't get in classical theories. In classical theories there are simply no states that attribute distributions of values for observables. It is only single numerical values that are being attributed by classical theories, hence no uncertainties the likes of Heisenberg's.
@@alexanderkohler6439 I didn't have time to read your long posting, but you are quite wrong in claiming that Fourier mutual precision is not identical to Heisenberg mutual precision. In Fourier, the two measurements, time and frequency, are related in the same way as in Heisenberg the two measurements, location and momentum, are related. I'm really sorry you don't understand this, but Heisenberg uncertainty is not magic and is not special quantum mysticism. It is just due to the inverse precision relationship between any function x and its related function dx/dt.
@@david203 I did not claim that. I said the Heisenberg principle was not a classical law. It is not a classical law, because you simply don't have that type of uncertainty relationship between position and momentum in classical theories. In addition, classical measurements of positions and momenta have nothing to do with distributions of signals in the time and frequency domain that Fourier cared about and that you try to reference. Sure, for the latter you have the same sort of uncertainty relationship between the variances of the respective signal distributions in time and frequency as you have it for the variances of the respective distributions in position and momentum in quantum (not classical) theory. And yes, the mathematical reason for this similarity is the same: It is the Fourier transform that relates the two distributions in either of these pairs. But that does not change anything with respect to the fact, that you don't have that uncertainty relationship in classical theories which makes the Heisenberg principle a result of quantum mechanics and not of classical mechanics. In classical mechanics positions and momenta are always well defined without any uncertainties. When you describe a pendulum in terms of classical mechanics you can always specify the position and the momentum of this pendulum at any time with arbitrary precision, i.e. no uncertainties. Fourier's result about signal distributions in time and frequency does not change that.
@@alexanderkohler6439 I'm sorry, none of this is correct, and I'm under time pressure to complete a project. The reason you can measure speed and momentum simultaneously in classical mechanics is that the "uncertainty" in precision is too small to measure with instruments of our size. It only becomes apparent at dimensions of the atom, which is unthinkably small. We'll have to agree to disagree and I hope you get a chance to learn this stuff someday.
@@david203 Classical mechanics is a mathematical theory that exists independently from any measurements one might or might not perfom in the real world. This theory uses mathematical objects like symplectic manifolds (phase spaces) and precise coordinates (position and momentum) on these manifolds in its goal to describe the state of systems that you find in the real world. These mathematical objects are not aware of any uncertainties in position and momentum that you actually observe in the real world when you "look" very closely. This is why there is no Heisenberg principle in classical mechanics as a mathematical theory. This is why classical mechanics as a mathematical theory ultimately fails in its goal to give a correct description of the real world. This is why you need to have another mathematical theory that uses other mathematical objects than classical mechanics does in order to achieve the goal of getting a correct description of the real world. That theory has to use mathematical objects that are inherently aware of these uncertainties that you observe in the real world. There actually is such a mathematical theory, called quantum mechanics which incorporates all this. The Heisenberg principle is a result of that mathematical theory called quantum mechanics. The Heisenberg principle is not a result of the mathematical theory called classical mechanics.
I don't feel a need to look up "free will." I know exactly what *I* mean when I say it. I mean that I have agency. I can act as a source of causation in the world, through my own personal choices. I just don't buy that those actions are "pre-determined" in some way and via some never properly explained mechanism I just "think" they're my choices. Among other objections, if physics can already take care of all that stuff, why am I even here aware of it at all? That claim has always felt like a cop out to me (but it's not the only cop out in science on issues of mind).
Predetermination doesn't mean that someone who doesn't know you tells you what to do. Predetermination means that your actions and thoughts can all be explained based on what events have happened to you, to make you who you are. Does that help?
According to Bell we need a nonlocal theory. Five minutes spent playing around with the Minkowski formalism will suggest that there is more than one way to travel faster than light. After another five minutes we might think about associating one of these ways with wavelike behaviour, and the other way with particle-like behaviour. If someone can show that I have the associations the wrong way round, I would be delighted. Otherwise it's a matter of working out how to make use of tachyonic Brownian motion in a computer simulation which will allow us to do numerical experiments with detectors made of antimatter.
There is absolutely no way to travel or send information faster than light. This was proven by Einstein and has never been disproven. There is no such thing as "tachyonic Brownian motion" and no tachyons have ever been discovered.
Interesting to hear he tends to view the wave function as epistemic, rather than ontic. I feel the same way; also that much more is needed to 'understand' whatever is going on. As a physicist, I've been digesting the many interpretations of QM for almost six decades, and still vacillate.
Nobody asks you to shut up and calculate in physics courses. Most students are simply not interested in thinking about the why the theory is the way it is.
1. Thinking about how to use a random number generator in any computer simulation of quantum mechanics. 2, Modification of the received equations of quantum mechanics is prohibited. 3. If points 1 and 2 appear to contradict each other, then the answer is that we can have tachyonic Brownian motion which is orthogonal to everything else. 4. The simulation needs to be able to shift information faster than light. Use of an RNG allows a Vernam cipher to be set up to do this. 5. Doing a computer simulation of Bell's inequalities with one detector made of antimatter.
Every point in the field has the same information. When an observer passes through it , yesterday (the past) interacts with tomorrow (the future, ,delayed choice) and it make the Now ( the observers perspectives at that time) three collapse's of the same state making a virtual background we see,
Inside our atmosphere brane we have a multiverse of points and many worlds Every point has it is own time frame.it is one point being everything at the same time in the virtual background
