Is nature really as strange as quantum theory says — or are there simpler explanations? Neutron measurements prove: It doesn’t work without the strange properties of quantum theory.
Quantum theory allows particles to exist in superposition states, defying classical realism. The Leggett-Garg inequality tests this by comparing quantum behavior against classical expectations. Recent neutron beam experiments at TU Wien confirmed that particles do violate this inequality, reinforcing the validity of quantum theory over classical explanations.
Quantum Superposition: Can Particles Be in Two Places at Once?
Can a particle be in two different places at the same time? In quantum physics, it can: Quantum theory allows objects to be in different states at the same time – or more precisely: in a superposition state, combining different observable states. But is this really the case? Perhaps the particle is actually in a very specific state, at a very specific location, but we just don’t know it?
The question of whether the behavior of quantum objects could perhaps be described by a simple, more classical theory has been discussed for decades. In 1985, a way of measuring this was proposed: the so-called “Leggett-Garg inequality.” Any theory that describes our world without the strange superposition states of quantum theory must obey this inequality. Quantum theory, on the other hand, violates it. Measurements with neutrons testing this “Leggett-Garg inequality” have now been carried out for the first time at TU Wien – with a clear result: the Leggett-Garg inequality is violated, classical explanations are not possible, quantum theory wins. The results have now been published in the journal Physical Review Letters.
Exploring Physical Realism
We normally assume that every object has certain properties: A ball is at a certain location, it has a certain speed, perhaps also a certain rotation. It doesn’t matter whether we observe the ball or not. It has these properties quite objectively and independently of us. “This view is known as ‘realism’,” says Stephan Sponar from the Atomic Institute at TU Wien.
We know from our everyday experience that large, macroscopic objects in particular must obey this rule. We also know that Macroscopic objects can be observed without being influenced significantly. The measurement does not fundamentally change the state. These assumptions are collectively referred to as “macroscopic realism.”
Quantum Theory and Macroscopic Realism
However, quantum theory as we know it today is a theory that violates this macroscopic realism. If different states are possible for a quantum particle, for example, different positions, speeds, or energy values, then any combination of these states is also possible. At least as long as this state is not measured. During a measurement, the superposition state is destroyed: the measurement forces the particle to decide in favor of one of the possible values.
Nevertheless, the quantum world must be logically connected to the macroscopic world – after all, large things are made up of small quantum particles. In principle, the rules of quantum theory should apply to everything.
So the question is: Is it possible to observe behavior in “large” objects that cannot be reconciled with our intuitive picture of macroscopic realism? Can macroscopic things also show clear signs of quantum properties?
Understanding the Leggett-Garg Inequality
In 1985, physicists Anthony James Leggett and Anupam Garg published a formula with which macroscopic realism can be tested: The Leggett-Garg Inequality. “The idea behind it is similar to the more famous Bell’s inequality, for which the Nobel Prize in Physics was awarded in 2022,” says Elisabeth Kreuzgruber, first author of the paper. “However, Bell’s inequality is about the question of how strongly the behavior of a particle is related to another quantum entangled particle. The Leggett-Garg inequality is only about one single object and asks the question: how its state at specific points in time related to the state of the same object at other specific points in time?”
Stronger Correlations Than Classical Physics Allows
Leggett and Garg assumed an object that can be measured at three different times, each measurement can have two different results. Even if we know nothing at all about whether or how the state of this object changes over time, we can still statistically analyze how strongly the results at different points in time correlate with each other.
It can be shown mathematically that the strength of these correlations can never exceed a certain level – assuming that macroscopic realism is correct. Leggett and Garg were able to establish an inequality that must always be fulfilled by every macroscopic realistic theory, regardless of any details of the theory.
However, if the object adheres to the rules of quantum theory, then there must be significantly stronger statistical correlations between the measurement results at the three different points in time. If an object is actually in different states at the same time between the measurement times, this must – according to Leggett and Garg – lead to stronger correlations between the three measurements.
Neutron Beams: Centimeter-Sized Quantum Objects
“However, it is not so easy to investigate this question experimentally,” says Richard Wagner. “If we want to test macroscopic realism, then we need an object that is macroscopic in a certain sense, i.e. that has a size comparable to the size of our usual everyday objects.” At the same time, however, it must be an object that has a chance of still showing quantum properties.
“Neutron beams, as we use them in a neutron interferometer, are perfect for this,” says Hartmut Lemmel, instrument responsible at the S18 instrument at the Institut Laue-Langevin (ILL) in Grenoble, where the experiment was conducted. In the neutron interferometer, a silicon perfect crystal interferometer that was first successfully used at the Atomic Institute of TU Wien in the early 1970s, the incident neutron beam is split into two partial beams at the first crystal plate and then recombined by another piece of silicon. There are therefore two different ways in which neutrons can travel from the source to the detector.
“Quantum theory says that every single neutron travels on both paths at the same time,” says Niels Geerits. “However, the two partial beams are several centimeters apart. In a sense, we are dealing with a quantum object that is huge by quantum standards.”
Violating the Leggett-Garg Inequality With Neutrons
Using a sophisticated combination of several neutron measurements, the team at TU Wien was able to test the Leggett-Garg inequality – and the result was clear: the inequality is violated. The neutrons behave in a way that cannot be explained by any conceivable macroscopically realistic theory. They actually travel on two paths at the same time, they are simultaneously located at different places, centimeters apart. The idea that “maybe the neutron is only traveling on one of the two paths, we just don’t know which one” has thus been refuted.
“Our experiment shows: Nature really is as strange as quantum theory claims,” says Stephan Sponar. “No matter which classical, macroscopically realistic theory you come up with: It will never be able to explain reality. It doesn’t work without quantum physics.”
Reference: “Violation of a Leggett-Garg Inequality Using Ideal Negative Measurements in Neutron Interferometry” by Elisabeth Kreuzgruber, Richard Wagner, Niels Geerits, Hartmut Lemmel and Stephan Sponar, 24 June 2024, Physical Review Letters.
DOI: 10.1103/PhysRevLett.132.260201
30 Comments
you know its all in your head dont you?
like, the world you see is a process of your brain?
Only between head knocks. (Look out for those, they may hurt!)
Is nature really as strange as quantum theory says — or are there simpler explanations? Neutron measurements prove: It doesn’t work without the strange properties of quantum theory.
Quantum theory allows particles to exist in superposition states, defying classical realism. The Leggett-Garg inequality tests this by comparing quantum behavior against classical expectations. Recent neutron beam experiments at TU Wien confirmed that particles do violate this inequality, reinforcing the validity of quantum theory over classical explanations.
VERY GOOD!
Ask researchers to think deeply:
1. What is the physical reality described by quantum theory?
2. Is quantum high-dimensional spacetime matter or low dimensional spacetime matter?
3. Can low dimensional spacetime matter be the substructure of high-dimensional spacetime matter?
4. Where does quantum gravity come from?
5. Can topological vortices generate gravity?
6. Do topological vortices have mass?
and so on.
Spin is crucial in the evolution of spacetime motion of cosmic matter.
Based on the ideal fluid physics characteristics of space, there is no eternal mass, but eternal fluid mechanics. In the interaction and balance of topological vortex fractal structures, spin creates everything (including gravity), and spin creates the world.
The universe does not make algebra, formulas, or fractions. The universe is a superposition, deflection, and entanglement of geometric shapes, is the interaction and balance of countless topological vortex fractal structures. In these interaction and balance, the past is difficult to change. For the future, some predictable, some unpredictable. But, the present moment is real, certain, and actionable. Physics should not ignore that low dimensional topological fractal structures are the material basis of high-dimensional spacetime.
Scientific research guided by correct theories can help humanity avoid detours, failures, and pomposity. Please witness the exemplary collaboration between theoretical physicists and experimentalists (https://scitechdaily.com/microscope-spacecrafts-most-precise-test-of-key-component-of-the-theory-of-general-relativity/#comment-854286). Some people in contemporary physics has always lived in a self righteous children’s story world. Whose values have been overturned by such a comical and ridiculous reality?
Misguided by the pseudo-scientific theory of Physical Review Letters (PRL), many researchers do not consider the similarities and differences between geometric shapes and physical reality in physics research, but indulge in imagination, and some scholars’ physics research seriously deviates from science, and they are almost unaware of the dirtiness and ugliness. Although mathematics is the language of science, it must be understood correctly.
1. Is Physical Review Letters (PRL) scientific?
2. Is Physical Review Letters (PRL) honest?
3. Is Physical Review Letters (PRL) trustworthy?
““Our experiment shows: Nature really is as strange as quantum theory claims,” says Stephan Sponar.” You have no other evidence, and it is a scientific result – against your personal opinion.
“Physical Review Letters (PRL), established in 1958, is a peer-reviewed, scientific journal that is published 52 times per year by the American Physical Society. As also confirmed by various measurement standards, which include the Journal Citation Reports impact factor and the journal h-index proposed by Google Scholar, many physicists and other scientists consider Physical Review Letters to be one of the most prestigious journals in the field of physics.[1][2][3]” [Wikipedia]
Physical Review Letters (PRL) firmly believe that two high-dimensional spacetime objects (such as two sets of cobalt-60) rotating in opposite directions can be transformed into two objects that mirror each other. Is it scientific?
CP violation opened the dirtiest and ugliest era in the history of physics (https://scitechdaily.com/microscope-spacecrafts-most-precise-test-of-key-component-of-the-theory-of-general-relativity/#comment-854286).
Like all of the journals in the Physical Review family, PRL is a member of the Physical Review family. Since Physical Review serves the research community, the difference between Physical Review Letters (1958) and Physical Review Journals (1956) cannot be an excuse for them to escape responsibility.
The Physical Review journals, encompassing both hybrid and open-access journals, features 17 peer-reviewed publications including Physical Review Letters, Physical Review X, and Reviews of Modern Physics. CP violation was published in Physics Review in 1956. All peer-reviewed publications of Physical Review family are responsible for clarifying this.
“Can a particle be in two different places at the same time?”
This is a wrong question because the concept “particle” is something we borrowed from macroscopic condensed matter that we try to project into the microscopic realm. There are no particles but fields are good representations of physical reality. Particles are only particular states of the fields. The world is of course objectively real if you stop to insist to envisage the physical reality in terms of concepts we acquired from our experience in macroscopic world.
Fields are good representations of physical reality. Particles are only particular states of the fields.
High Perspicacity!
You may enjoy particle physicist Matt Strassler’s take:
“In my role as a teacher and explainer of physics, I have found that the ambiguities and subtleties of language can easily create confusion. This is especially true when well-known English words are reused in scientific contexts, where they may or may not be quite appropriate.
The word “particle”, as used to describe “elementary particles” such as electrons and quarks and photons, is arguably one such word. It risks giving the wrong impression as to what electrons etc. are really like. For this reason, I sometimes replace “particle” with the word “wavicle”, a word from the 1920s that has been getting some traction again in recent years.”
“From the perspective of quantum field theory, as I’ve outlined here, a wavicle does have features of both waves and particles, but it also lacks features of both waves and particles. For this reason, I would personally prefer to say that it is neither one. I don’t think it’s useful to say that it is both wave and particle, or to say that it is sometimes wave and sometimes particle. It’s simply something else.”
[“Particles, Waves, and Wavicles” @ his blog]
I agree with your assessment, the experimental results only looks odd if you don’t expect what the quantum theory predicts. The old saw that real means “if I kick a large stone and it kicks back” works here. If the stone is a bit fuzzy between kicks, who cares!?
It looks to me like just another failure to factor-in gravity as the ambient radiant pulsing angular lines of attractive force that it is, capable of influencing small particles but not macroscopic objects.
If you are really interested in science, you can refer to https://arxiv.org/ftp/astro-ph/papers/0410/0410365.pdf.
If you are really interested in science and physics, you can refer to https://arxiv.org/ftp/astro-ph/papers/0410/0410365.pdf.
Thanks for the advice but after browsing some of what you linked me to, I still believe I demonstrated the true nature of gravity with reproducible experiments first uploaded to my YouTube video channel in 2012 and now at: “1Gravity:” https://odysee.com/@charlesgshaver:d/1Gravity:8 Think ‘boat propellers turning in bodies of water’ in place of wheels with invisible blades rotating in the earth’s ambient field of gravity.
VERY GOOD.
The physical phenomena observed in scientific experiments are always appearances, not the natural essence of things. The natural essence of things needs to be extracted and sublimated via experimental data.
Enjoy your every day.
@Bao-hua ZHANG: Just remember that arxiv is pre-publishing, not peer published results. S.A. Orlov has not arxiv published anything else, and there is no established “Theory of Vortex Gravitation”. I wouldn’t use it as a reference.
So your only interest was to promote or spam your non-published personal notions, which had nothing to do with the article results!? Please don’t.
The so-called academic journals (such as Physical Review Letters, Nature, Science, etc.) firmly believe that two high-dimensional spacetime objects (such as two sets of cobalt-60) rotating in opposite directions can be transformed into two objects that mirror each other. Are they scientific?
CP violation opened the dirtiest and ugliest era in the history of physics (https://scitechdaily.com/microscope-spacecrafts-most-precise-test-of-key-component-of-the-theory-of-general-relativity/#comment-854286). Is this your so-called peer published results?
The brainwashing effect of the Physics Review Letters (PRL) on its followers is truly amazing. If you are interested, you can continue to browse the comments of https://scitechdaily.com/quantum-gravity-unveiled-scientists-crack-the-cosmic-code-that-baffled-einstein/.
You are indeed an outstanding pupil and fierce follower of peer published results.
Good luck to you.
There is shown a graphic with two detectors at the experiment endpoints and one smaller detector at a midway point. No idea what how the two kinds of detector work here, but all detectors ultimately rely on electromagnetism, as a matter of principle.
I doubt nature is generating an energy-doubling failure of the conservation of energy principle, seems much more likely the splitter plate produces a split pair of energy packets from energy knocked out of it, and the combiner plate recombines that energy.
There is no energy doubling suggested here. The incoming flux of a (good) beam splitter is halved in each outgoing beam.
The energy of superpositions are not observed until the wavefunction superpositions are collapsed. But the experiment wavefunctions are not the neutron waves (wavicles, or “particles”) but their state functions (probabilities of being observed).
“There is no energy doubling suggested here.”
Incredibly perceptive! Where were you educated? Must know so I can move there and take a class!
Anyway, my preference is to consider regulated particle beams as streams of dipole pairings, alternating spin-up/spin-down pairings are naturally formed in the regulated beam. Nothing wrong with considering that as a possibility with a beam of neutrons.
Another possibility to consider may be that the front and back of the beam particle have opposing interactions with the splitters and the polarizing medium may be naturally set up to respond to each interaction in complementary ways. The particle could move along with one interaction while the other interaction travels alone on the other path.
“The particle could move along with one interaction while the other interaction travels alone on the other path.”
It’s a 50% pilot wave concept. The pilot particle is ultimately just there to observe the recombination, which would mean 50% of the time one leg picks up the gravity. The pilot would donate enough energy to track with the front half polarizer effect and the polarizer would donate the rest.
I mean basically I’m just a “realist,” particularly, but not necessarily, a “local realist,” when it comes to evaluating invisible stuff. Information without local realism is incomplete, in other words.
Polarizers are a perfect example a realism problem, to me. If light or energy is polarized by gravitational bending instead of pretending a constant speed, then there could exist the political catastrophe of ceding to Euclid an ultimate relevance in the universe. so, endless Einstein celebration politics would give all the more reason to keep the magic of particles interacting with polarizers spooky (unreal in practically every sense not left unexploited).
The suggestion would be that the polarizer generates a “virtual neutron” possibly modelled with an empty “vortex-shaped” field missing only a neutron with real mass at its core. As a vortex it may move independently of core spin rate. Since neutron don’t last very long there’s no obvious test of virtual particle dissipation without recombination.
“There is no energy doubling suggested here.”
Let’s just suppose for grins that you’re in two places at once and you always bring a fair scale with you instead of a biased selfish over-rewarded scale.
“the experiment wavefunctions are not the neutron waves (wavicles, or “particles”) but their state functions (probabilities of being observed)”
Suppose the “real” neutron, in-toto, can be divided into its internal context-free neutron state and its surrounding context-responsive vacuum state which is a wide-spread continually-updated propagating particle-vacuum energy feedback effect of sorts. Divide the particle and the polarizer each into two vacuum-state halves, front and back. Supposing the polarizer re-directing the particle with 0% or 50% probability may produce the same result. On the other hand the front half of a piloted particle-wave combination response of the polarizer may want to stick with the undeflected particle response. Ultimately it’s yet another otherwise-invisible dipole effect and a lot of original-neutron-less polarized vacuum excitation possibilities to consider.
Suppose there’s a particle consisting of a positively charged sphere covered by a negatively charged sphere. As long as the particle spins, the front behaves like the opposite of the back. One might suppose the anti-particle to such a particle would have the front and back reversed, with the layering of the charges reversed, also making the moving particle loosely “time-reversed” in that sense, as one particle half waves left to right and the other half waves right-to-left. The polarizer apparently has two self-cancelling internal opposing responses, collectively leaving it largely unaffected soon after the neutron passes, and continual vacuum feedback from two self-cancelling split external half-responses.
There is no energy doubling suggested here.
It’s okay, shameless eventual hit-and-runner, you just missed the big part in front where the article says: “Can a particle be in two different places at the same time? In quantum physics, it can…” – another reddit language problem thing from Mr. Norther Euro-socks the convenient viking black cat.
“There is no energy doubling suggested here.”
Where’s that, in Randy’s scholastic black flex lagoon?
“probabilities of being observed”
Chances of you being true to form and reappearing here are practically zero if you get shown up as a BS apologist for standard BS media tripe, so I’ll try to avoid that in the future.
Nice! It was expected in quantum physics that macroscopic objects behaves like microscopic objects, only that they are easier to disturb (observe). Feynman path integrals describe single particle paths in the manner of what the observed correlations say:
“It replaces the classical notion of a single, unique classical trajectory for a system with a sum, or functional integral, over an infinity of quantum-mechanically possible trajectories to compute a quantum amplitude.” [“Path integral formulation”, Wikipedia]