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Quantum particles feel the influence of gravitational fields they never touch

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Re: Quantum particles feel the influence of gravitational fields they never touch

#41

Post by pdonis »

martopix wrote: post #32
pdonis wrote: post #23

Earlier quoted context omitted.

> They measured a bigger gravitational effect on the particle No, they didn't. They measured a phase shift in the particle's wave function. There is no "gravitational force" in free fall, and the particles were in free fall. > gravity decreases with distance squared The Newtonian gravitational force does, but the Newtonian gravitational force is irrelevant for an experiment conducted in free fall, as this one was. Th…

> There is no "gravitational force" in free fall, and the particles were in free fall. what is free fall in a reference frame is a particle subject to a force in another reference frame.

No, it isn't. Free fall is invariant: attach an accelerometer to the object and it reads zero. That is true regardless of your choice of reference frame.

Re: Quantum particles feel the influence of gravitational fields they never touch

#42

Post by pdonis »

kenjackson wrote: post #33
pdonis wrote: post #22

Earlier quoted context omitted.

The "filter out the effects of gravitational forces" means that the measured particles were in free fall; in free fall there is no gravitational force.

Is that the common way you'd express that they were measured in free fall -- that the effects were "filtered" out? That seems like an odd way of saying it, but I'm not a physicist.

I don't think it's a very good way of expressing that the objects were in free fall, no. Nor, as far as I can tell, does the actual paper (as opposed to the pop science article) use such an expression.

Re: Quantum particles feel the influence of gravitational fields they never touch

#43

Post by cashsterling »

squeaky-clean wrote: post #25

I know this is a trope that comes up in half of the posts involving a journal article, but scientific journal pricing is so confusing to me. I can pay $30 for digital access to a 4 page article (it says Vol 375 pg 226-229). Or I can pay $15 and get the entire issue of Vol 375 in print? Or I can pay $80/yr to join AAAS and get "50 issues of Science", but which issues? I assume they mean the upcoming year of issues, bu…

i think a possible startup idea would be to start a "Github for science" (replace "science" with any academic or interest area really). Encourage folks to post their papers in latex or markdown. Post their data, code, mechanical and electrical drawings, videos and pictures of their experimental setup, videos explaining their research, videos performing the experiment?, and so on. Allow others to comment on research with questions, concerns, suggestions for enhancement, or link it to their own supporting work, etc. Allow other researchers to fork people's research (but all forks link back to the original to give full attribution). The core focus is open up access to academic papers and research, foster better communication between people, and set a higher bar for communication of research.

Going the non-profit route: I think it would be cool for the site to be federated/distributed so universities & countries could host replicated nodes. It would be best if somehow the software system development and hosting costs could be underwritten by governments and universities.

Going the for-profit route: The site could have an inexpensive PRO account to help support the site and software development. The site could be add supported, but zero tracker, with adds that would be small and content-based purely on the content of the paper topic.

Add Examples: Reading an article on Julia numerical programming... maybe show an add for the upcoming JuliaCon or Julia Computing

Reading a metallurgy analysis paper... maybe show a small add for an x-ray fluorescent system for metal composition analysis or advertise an upcoming metallurgy conference

... the idea being that these adds are (1) not targeted at users, just targeted at content, (2)small, dismiss-able, and not annoying (3) hopefully actually useful and interesting to the reader.

The site could also sell "advanced API access" to interested parties for knowledge management/search on fast trending research and topical areas, research community graph analysis (maybe for recruiting?)... kind of the LinkedIn layer of the site.

Re: Quantum particles feel the influence of gravitational fields they never touch

#44

Post by amelius »

notfed wrote: post #35
sandworm101 wrote: post #29

I don't see the new. All this tells me is that entangled particles react to things that impact some but not all of their various superpositions/entanglements. Sounds like basic double-slit stuff to me. The particle that goes through the slit A reacts to its partners going through slit B. The particle that passed through gravity field A reacted to its partners going through field B.

Quantum mechanics news hasn't been giving us anything new for decades. Every modern article is about a new speculation, or at best an or experiment that reconfirms what we already knew. Yet, articles will never cease to use click-bait to make you think a revolution has occurred.

There was an article about China reaching quantum supremacy some time ago, so I suppose we achieved something.

Re: Quantum particles feel the influence of gravitational fields they never touch

#45

Post by monocasa »

bubblecheck wrote: post #37

(Per the article): Is it correct to describe superposition as the probability of, e.g., an electron being in one of two places? In such an example, is it instead correct to say that superposition is a probability distribution of infinitely many possible locations?

It depends. In the general case a superposition is a probability field with infinitely many options once the waveform collapses, but the specifics of the experiment might discretize that practically into two options.

Re: Quantum particles feel the influence of gravitational fields they never touch

#46

Post by dang »

quantum_state wrote: post #36

Completely misleading and eye ball gripping “article’ …

Quite possibly, but a comment like this is only helpful if it explains how the article is misleading—i.e. if it provides more correct information on the topic. Otherwise it's just another low-quality dismissal, which we're trying to avoid here.

https://news.ycombinator.com/newsguidelines.html

Re: Quantum particles feel the influence of gravitational fields they never touch

#47

Post by dekhn »

diontron wrote: post #7
JaimeThompson wrote: post #6

Earlier quoted context omitted.

What about the use of quantum physics in things like semiconductors?

semiconductors don't "use" quantum physics, quantum physics just tries to explain how they work. semiconductors still exist without requiring quantum physicists to come in and try and steal credit for something they had no influence on whatsoever.

This is sort of a profoundly different way of looking at it. The creation of the first semiconductors was closely tied to the development of quantum theory around electrons in metal. Bell labs hired up Shockley, Bardeen and a bunch of other solid state physicists (when it started to become obvious that the US needed to build computing devices that were faster and more rugged than vacuum tubes) and it was their knowledge of quantum physics that enabled them to solve key problems in the development of the transistor.

QM is still the best theory for semiconductors and a lot of semiconductor improvement happens by applying quantum physics.

The important part to recognize is that this is a part of QM that doesn't involve entanglement or wave function collapse, but definitely relies heavily on quantum tunnelling. All of this is well documented by the primary literature in the field.

Re: Quantum particles feel the influence of gravitational fields they never touch

#48

Post by Koshkin »

pdonis wrote: post #21
changoplatanero wrote: post #3

I'm not sure how it's possible to "never touch" a gravitational field given that they extend throughout the universe and are impossible to be shielded.

As is unfortunately common in pop science writeups, the article gives a garbled description of what the Aharonov-Bohm effect actually is. The key point is not that "the field never touches the particles". The key point is that the potential , rather than the field, has an observable effect. In classical gauge theories, the potential itself is not considered to be observable; only the field (the gradient of the potent…

> description

Importantly, it's "famed" and "eerie."

Re: Quantum particles feel the influence of gravitational fields they never touch

#49

Post by mikewarot »

pdonis wrote: post #21
changoplatanero wrote: post #3

I'm not sure how it's possible to "never touch" a gravitational field given that they extend throughout the universe and are impossible to be shielded.

As is unfortunately common in pop science writeups, the article gives a garbled description of what the Aharonov-Bohm effect actually is. The key point is not that "the field never touches the particles". The key point is that the potential , rather than the field, has an observable effect. In classical gauge theories, the potential itself is not considered to be observable; only the field (the gradient of the potent…

You're right, most descriptions of Aharonov-Bohm fail to mention Electromagnetic Potential, and just describe it as quantum woo. I'd love to have an actual quantum detector, like a SQUID, to do some physics experiments with.

Re: Quantum particles feel the influence of gravitational fields they never touch

#50

Post by mikewarot »

ianai wrote: post #9

Sounds more like a demonstration of an ability to detect the influence of gravitational fields at scales previously unavailable. Specifically, in testing something called the "Aharonov-Bohm influence/[effect]" previously demonstrated within EM fields and now for gravity. Quote: """ The study not only reveals a famed physics effect in a new context, but also showcases the potential to study subtle effects in gravitati…

The wavelength of an atom (DeBroglie Wavelength) is much lower than that of a photon of visible light, so it follows that anything that makes the path of one beam even slightly longer, such as putting a mass near it, would be far more detectable in this manner.

There might be a small, very hard to detect optical interference shift if the experiment were re-run with a coherent laser beam.

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