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A Physicist Trying to Fix Quantum Mechanics
- lisper 6y agoTL;DR: Physicist Angelo Bassi is trying to experimentally test the GRW collapse model [1], which is in fact experimentally testable. Personally, my money is firmly on the side of these experiments failing, but I would not bet my entire life savings on it. These experiments may well succeed, and if they do, that will be the biggest breakthrough in physics in 100 years. It's great that someone is actually testing this. [1]https://en.wikipedia.org/wiki/Ghirardi%E2%80%93Rimini%E2%80%93Weber_theory https://en.wikipedia.org/wiki/Ghirardi%E2%80%93Rimini%E2%80%...
- hatmatrix 6y agoInteresting that such a potentially grand idea is published unceremoniously in a specialized journal (Physical Review D).
- lisper 6y agoFoundations work has historically not been taken very seriously within the physics community.
- leephillips 6y agoPhysicists generally publish their physics in physics journals. There is usually no public ceremony involved.
- deerpig 6y agoPhysical Review D is not a light weight journal. You don't get published there unless you are being taken seriously in the scientific community.
- seiferteric 6y agoNice! This is my favorite theory since it's so conceptually simple (I can actually understand it) but that of course has no bearing about it being reality.
- systemvoltage 6y ago> The imprecise talk of “observer” and a “measurement” that plagues the orthodox interpretation is thus avoided because the wave function collapses spontaneously. Why? Measurement is just a photon you shoot at something. Or electron. Wikipedia is saying we cannot define what an observer is and what constitutes “measurement” - sure we do, measurement interacts with the quantum mechanical system because we need to use something - a photon or an electron or some particle to see how it interacts with the system.
- gotostatement 6y agoI'm not knowledgable of QM. But I don't think that's necessarily true, because photons/electrons are interacting with the system at all times, but the wave function doesn't collapse until we actually observe the result of one of those photons/scatters/whatever, right?
- systemvoltage 6y agoSame, not too knowledgeable but I thought this was no longer a mystery.
- gotostatement 6y agomy point is that, a photon bouncing off the system doesn't suffice as a measurement, because photons and electrons are always interacting with the system, but the measurement/wave function collapse doesn't occur until there's some other type of observation that occurs, e.g. a photon that's specifically sent and read by the experimenter
- aeternum 6y agoSuppose you fire a photon through a polarizing filter. If the photon's polarization is orthogonal to the filter, it will be blocked however if not orthogonal, the photon can pass through with some probability. Does putting the photon through the filter count as a measurement?
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- andrewon 6y agoagreed. More physicists (but not all) should be doing something like this. This is what tenure system for.
- pdonis 6y agoAngelo Bassi has a number of papers on arxiv.org: https://www.google.com/search?q=angelo+bassi+site%3Aarxiv.org https://www.google.com/search?q=angelo+bassi+site%3Aarxiv.or... This one seems relevant to the topic of the NY Times article: https://arxiv.org/abs/1310.8600 https://arxiv.org/abs/1310.8600
- Mugwort 6y agoI disagree that quantum mechanics needs fixing. What it requires is understanding. Many people even ones with PhDs don't really have a deep understanding of QM. Ask a grad student or even a professor of physics what is essentially different about QM verses classical mechanics. I almost always get one of two answers. QM has operators acting on a Hilbert space (rigged HS). It's so mysterious because we have to replace everything with operators. well... Have they heard of the Koopman–von Neumann formulations of classical mechanics? It's CM formulated using HS and ops. https://en.wikipedia.org/wiki/Koopman%E2%80%93von_Neumann_classical_mechanics https://en.wikipedia.org/wiki/Koopman%E2%80%93von_Neumann_cl... Another answer is uncertainty. QM has uncertainty. Well... so does classical mechanics! So what is different? That's a very long answer but one thing is the Exclusion principle. Besides the KvN formulation is it possible to do QM using the equations of CM in the same form? yes, it is. The Wigner Moyal Weyl formulations of QM. Look it up or Moyal star products. Lastly, the collapse of the wave function. Already done long, long ago by John von Neumann in his book on Quantum Mechanics. The correct formulation involves the subtle concept of decoherence. Von Neumann's trace operators are used in extreme cases where standard calculations (which involve a tiny bit of cheating) won't work, e.g. black hole entropy. What's wrong with QM? So far nothing! It's possible someone might find a flaw but it hasn't happened. The problem is mostly US. We don't understand all the implications of what we already possess. The enormous amount of myth making and lack of understanding surrounding QM obfuscates what the true problems are which in 99% of cases is the most physicists simply haven't studied von Neumann carefully enough.
- AnotherGoodName 6y ago>QM has uncertainty. Well... so does classical mechanics! Wait what? I mean sure, at scale CM is not feasible to compute (eg. n body problem). But our inability to precisely compute the otherwise completely predictable events is not the same as QM which can give true randomness.
- fspeech 6y agoQM is essentially deterministic. Neither CM or QM allows for true randomness. Maybe at this stage it is only a philosophical issue. In the end Statistical Mechanics and Thermodynamics are what truly rule the world. There is no hard and fast rule on when QM should kick in. We adjust the rule based on the need, which is why we largely don't need to deal with foundational issues while interpreting the world in QM framework.
- whatshisface 6y agoThe idea that quantum mechanics stops working at macroscopic scales is totally unnecessary, as the fact that this appears to happen has already been explained with decoherence, which emerges naturally from the fundamental laws. However, I guess there's something to be said for checking every imaginable possible modification of present theories. As far as I know the only modification that's truly motivated is adding gravity to the standard model, which nobody knows how to do, so the next best thing is to imagine extra terms and then try to swat them out with experiments.
- lisper 6y ago> The idea that quantum mechanics stops working at macroscopic scales is totally unnecessary Except to explain our everyday experience of a single classical world. Then something in QM has to give.
- 8bitsrule 6y agoI've long suspected that part of the problem is that we don't yet have the right mathematics. The math we do have allows very accurate predictions ... it's right in that sense ... and some (clouded) insight. Epicycles did work for the solar system. But the modern solution was much simpler.
- lisper 6y agoThe Schroedinger equation and the associated linear algebra are pretty fleepin' simple. Turning the crank can be hard but the underlying concepts are already about as simple as they could be.
- AnimalMuppet 6y agoObjection, your honor. Assumes facts not in evidence.
- archgoon 6y ago>Except to explain our everyday experience of a single classical world. Which the parent says is explained via decoherence. Why do you feel that decoherence does not account for the observed phenomenon?
- throwaway_jobs 6y agoThis reminds me of Carl Sagan, who basically said while people believe the beautiful math and wave functions are the fundamental reality and a universal language, he didn’t actually believe this and thought there was something more and very simple behind the math we use to understand/explain our observations and make predictions.
- Koshkin 6y agoProblem is, math is the only “microscope” we have a hope to peer with into the fundamental reality. On the other hand, the wave function is just as real as, say, the number “3” is.
- stared 6y ago> the wave function’s numbers have no obvious meaning A lot of things in physics (or in other model in science, for that matter) have cannot be measured directly. (I think "has no meaning" is a stretch here.) I can go for ages talking about things in physics that are less intuitive than simple, non-relativistic, quantum mechanics (Poynting vector, anyone?) But think about something simple and concrete: electric potential. You cannot measure it. But you can measure its difference.
- mcnamaratw 6y agoI am not disagreeing with your overall point, but they sell meters that measure electric potential. We measure it all the time.
- AnimalMuppet 6y agoNo, they measure the electric potential difference between two points. This is why, for example, you ground your scope probes.
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- mcnamaratw 6y agoOnly the potential difference is physically meaningful. The absolute potential has no effect on anything. You can add 1000 V or 10^6 V to everything and you get exactly the same physics.
- corty 6y agoThere are some systems (Schottky junctions iirc) where you can semidirectly sample a wave function via a voltage.
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- wavegeek 6y agoGiven the (according to me) fact that many worlds (more aptly named the Relative State Interpretation) is true and correct, one can confidently predict that no "collapse" will be found. That, and the fact that people have been looking for actual collapse of the wave function for many decades.
- lambdatronics 6y agoThe MWI is a cop-out. The problem of nonlocality just gets handed off to whatever process forks the parallel universes - it has to ensure that every universe has consistent outcomes for both halves of a Bell experiment, for instance. The probabilities in QM should be viewed as subjective, but physicists hate subjectivity, so they talk about hypothetical ensembles. It baffles me that Everett took those ensembles and decided they were real universes.
- rubidium 6y agoHere here! I just met one other person on the internet who sees that the emperor has no clothes. The adherence and attractiveness of MWI to so many CS programmers (and a few physicists) is mind boggling to me.
- akvadrako 6y agoThe MWI van violate Bell inequalities locally by using post-selection; that’s trivial to show. When the universe splits at two distant measurements it isn’t until those outcomes are brought into contact that the matching of worlds needs to happen.
- engineeringwoke 6y agoI know there's math that makes this seem real, but logical arguments make it sound silly. Does the universe split every time the wave function collapses in any form, for all measurements of all atoms in the universe? Isn't that essentially infinite? And how would you prove it if any of this was real?
- nwallin 6y ago