An ultra-precise clock shows how to link the quantum world with gravity
quantamagazine.org
quantamagazine.org
Just in case there is anyone here who didn't read the article (surely not?), for whom this summary might not convey the full astoundingness of the procedure, what they are actually measuring is the difference in the passage of time itself, due to gravity, when a millimeter higher up than the other.
It could be that time dilation is caused by some underlying physical system having a bottleneck, thus causing the slowdown. The underlying physical system has to evaluate all possible states for a particle in superposition, even if working in parallel. Then i would guess a particle in superposition should always experience the biggest possible slowdown.
To your point, maybe, I wonder if they had to factor in the relative velocity difference of the top and bottom of the cloud due to the rotation of the earth at their latitude (or just do the experiment at the south pole). At the equator, assuming a cloud of 1mm diameter, it would be 2π mm/day, which according to a sloppy google search is 2.425675e-16c.
The team here measured the gravitational redshift by comparing the clock-rates inferred from atoms at the top and bottom of a cloud of atoms that was itself smaller than a grain of rice.
I've spent much of my career building precision gravity-sensing systems -- I'm happy to assure you that this news is very cool. Clocks are an awesome way to learn a lot of new things about gravity, particularly because they measure differences in potential, rather than differences in acceleration. In the past two decades, we have seen atomic clocks begin to become sensitive to terrestrial gravity. In the next two decades, we are likely to see clocks begin to open up previously-impossible measurements.
The measurement described here is a wonderful stepping-stone on that path.
800 nanokelvins down to 100 nK! Brrr! [https://arxiv.org/abs/2109.12238 "Atomic sample preparation", pdf p. 16, and top of p. 3]
Maybe it's soon time to plan updates to PARCS/ACES/SAGAS.
Time travels sliiiiiightly faster by my feet than by my head. So how does all of me stay put together? I would expect that even if the shift was really tiny, as soon as part of my body is not in the same time reference point as another part, it would go * poof *.
This is not how the physical reality works, in particular the first assumption doesn't hold. There is no global time. The mapping of 4-space is not only observer-dependent (special relativity) but it also is arbitrary, subject to mathematical constraints outside the level of this discussion (general relativity). Although perhaps it shouldn't be outside this discussion, because your definition of time is one that is not possible.
As an aside, it really grinds my gears when I see popular science articles describing astronomical observations as being "in the past". Pretty much by definition everything that affects us must be in our causal past light cone, so in a strict sense that statement doesn't say anything at all. But it does try to say something, it tries to make astronomical observations seem different from everyday observations. In particular, people have this intuitive but non-physical idea on "now" happening around us, and these articles try to give the impression that "now" in those faraway astronomical objects is different, as if the notion of "now" (either here or there) would be a real physical thing, when only the observer's now is physically meaningful. They implicitely talk about THE faraway "now" when the whole point of GR is that there isn't a unique such thing.
Articles get this backwards. The fact that light comes from the past is true both for astronomical phenomena and for everything else, that's not what's interesting, what's interesting is precisely that coordinate mappings can't be unique and by mixing ontologically different categories of "now", they obscure this idea further.
It would be quite difficult to play a video game hosted on the moon, for instance, because the moon is not part of our "now".
If the human brain ran at a slower speed, then our "now" would have a larger effective radius.
When you talk about equal-time coordinates in GR, the notion of now is non-unique, and this is interesting, but popular articles fail to convey this.
When you talk about the human notion of now, the notion of now is local, it's not that this notion of now in astronomical phenomena is different, it's that it can't be defined at all. Popular articles not only fail to convey this, but give the impression that it can be defined. It can't, and that is what is interesting.
There are multiple levels of category error happening simultaneously. The confusion between equal-time surfaces, and neighbourhoods (4-volumes) around points, along with the conflation of a point with its neighbourhood. And from these popular articles fail to convey the interesting properties of either -- the observer's choice in defining surfaces, and that 4-neighbourhoods can't be extended arbitrarily far while preserving their topological properties.
Writing an accurate "popular" article about GR might be impossible, because the topic is so far beyond human experience that only a fraction of the population could ever hope to hold it in their heads.
You can teach people that the concept of "now" is observer-dependent, but as long as we're stuck on Earth, that information is pretty useless. Software engineers working on stuff like global databases and video game synchronization might benefit somewhat from that way of thinking, but they're about as uncommon as physicists.
This GR thingy holds for every observation, even those here on Earth, but there the time-delay is small enough that we can ignore it. But if you think of it as the first stretch on a very long gradient all the way out to the stars where that difference becomes more manifest then what these researchers have just done is shown you is to prove that the gradient exists on every level of scale, likely all the way down to the interaction of two atoms in a gravity field, but for now we have it down to a mm or so.
This is a super impressive result and it makes this concept a lot more accessible than the 'Earth time is special' vs 'interstellar distances are in the past'. They're all in the past from the point of an observer, even if that observer is a few mm away from the event.
I assume the second one was supposed to be feet...
GR works equally well with all topologies of spacetime and we're just assuming that it's 3+1. The Kaluza-Klein theory adds a small 4th dimension and derives most of the EM equations out of GR. So I wonder if we just need to make a better guess what the timelike dimensions look like.
Entire topic is too big for my brain, but I think the cool kids these days consider classical theories of any sort to be uninteresting, that the universe is really an infinite dimensional quantum state, and that GR and everything else emerges from that. https://arxiv.org/abs/1801.08132
The answer to those questions is always “yes”, unless you’ve spent years of research to come up with <idea>.
This difference causes tidal forces in your body. These tidal forces are minuscule compared to any other everyday interaction that you do. I haven't done the calculation, but I would wager that the tidal effect of even 1 hour over a lifetime is completely dwarfed by everyday interactions and effectively invisible in human everyday life.
when I give it more thought, it feels to me that when we say time, we're really say how fast things move relative to other things, and that makes it easier to reason about how different parts of your body are not upset about experiencing time differently
So "adds up quickly" is relative (heh) in this case, and inconsequential in absolute terms, at human scale.
Somehow I found this so encouraging. At a time when it seems even some scientists are just itching for a chance to get in front of the media with very preliminary studies, it is nice to see a team that seems to value actually getting the science right and getting others expert opinions before making a media blitz.
Edit: maybe because these two forces have very different magnitude it is not possible to measure it
In fact gravity is even self-interacting with itself. ie. Gravitational fields themselves influence the propagation of gravitational fields. If this wasn't the case we'd observe gravitational waves from distance objects earlier than the speed of light. Which would be a problem for all our current models of physics if true.
Generally the space between us and distant objects isn't actually a perfect vacuum. It should have an index of refraction greater than 1, and it should vary by frequency. Light from a distant object should arrive here spread out in time by frequency, and the earliest should arrive a little later than something moving at the speed of light would arrive.
Is there something like the index of refraction for gravity waves? If not then we should see gravity waves from an event before we see any light from the event. If there is, then it should be possible for gravity waves to arrive before, at the same time, or after light from the same event depending on the frequency of the gravity wave and the light.
We have measured the relative speed of gravity and light. The difference is constrained to be no more that about 10^-15 times the speed of light. This us based on a signal that travelled 130 million light years.
Of course going faster than light which is being slowed by absorption and re-emission isn't the same as breaking the speed of light since light itself is going slower than the speed of light in this case.
So yes you're right that it isn't exactly the same arrival time but we're not talking about curvature differences here, we're talking about physical interactions that the light undergoes that gravity doesn't.
That said, I’m still trying to come to terms with the fact that breaking this speed limit just means that causality would be potentially broken. Isn’t that just something we axiomatically believed based on experience and we just haven’t observed otherwise?
Because of how the three dimensions of space and one dimension of time are put together, you can think of there being a balance or trade between motion in space and motion in time. If you aren't moving in space, you're moving through time at the maximum possible "rate". The more rapidly you move through space, the slower you move through time. This trade bottoms out at "c", at which point you're not moving through time at all. (Since motion is impossible without time passing, "c" itself is unachievable; you can only approach it asymptotically. Something about massless particles makes "motion" not a thing in the first place, I think, meaning they can actually propagate at exactly "c" as seen by an observer.)
You can visualize this as a dial on an X-Y graph which starts out pointing in the Y direction, and as you speed up, it turns more toward the X direction. When you're pointing completely in the X direction, you're moving "at the speed of light", purely in space and not at all through time. If you turn the dial even further, you're trading some of that speed back for motion in time... but in the opposite direction.
Of course, this is all super-handwavey; most importantly, velocity has to be measured relative to an observer, so all of this about rates has to be anchored relative to an observer. (But this is also precisely why massless particles propagate at the same rate regardless of observer -- insert timey-wimey Doctor Who reference.)
Greg Egan has a lovely trilogy, Orthogonal, set in a universe where space and time don't have this trade (formally, the sign on the time variable in some critical equation is flipped to match the spatial dimensions). He has some great material on the exact physics of such a world. [0]
Maybe the gravity emanates from outside the event horizon, but then why would it pull us inside?
Thanks
>The final conclusion of our analysis is that there appear to be no physically acceptable stable solutions of the MTZ system
https://arxiv.org/pdf/0710.1735.pdf
Basically it's a huge hole in black hole theory right now. It should be made clear though that both gravity is self interacting and black holes do exist. It's just when you get down to specifics it's a case of "we don't know how to make this work".
I assume punching a hole in spacetime, punches an equivalent hole in maths aswell
Let me ask a few simpler questions first, my main question is at the end
This punched hole might be like measuring angles with a differential. When the difference between the measured points hits zero, the other end of the equation hits infinity and the angle becomes meaningless
So would a true vertical curvature in spacetime equivalently require an infinite amount of mass?
They say that at the event horizon the deformation is so strong that from a black hole all paths lead inwards. But isn't gravity commutative? A.k.a. coming from inside, vertical curvature is reached. But if the curvature is vertical, then presumably there is also no way into a black hole?
---
So main question; could we just say that vertical curvature is impossible, and black holes are simply extreeeeme curvature to the extent that a 1.7second difference between light waves and gravitational waves over 130million years is enough to stop light escaping, but not gravity?
Is that solution too simple, what am i missing?
Thanks
Instead since light is redshifted as it exits a gravity well a better thought would be "is the almost but not quite black hole red-shifting light to the point of being impossible to detect?". After all light with almost 0hz frequency is basically non-interactive. It has a similar outcome. You could then have an 'almost black hole' that looks just like a real black hole but allows gravity to escape. https://arxiv.org/abs/2102.07769
> You could then have an 'almost black hole' that looks just like a real black hole but allows gravity to escape
I wondered if that answer to the conundrum could apply to all black holes. I suppose not
For real black holes, I suppose we should say they are not true singularities where the event horizon curvature goes vertical, but simply that curvature goes beyond the speed of light, so the maths still makes sense
Thanks that is a lot more logical
So then the effect of gravity from a real black hole would be like the effect of a messy person after they've left the room, and the reason why the effect of a black hole is felt for much longer is because of time dilation, and gravity doesn't experience redshift?
> astro-ph/2102.07769
This is about a particular model of dark matter that unlike in the standard cosmology is hot and has a particular radial profile within galaxies and outside galaxies undergoes a phase change to a uniformly distributed cold dark matter.
Tracing the gravitational collapse consequences of a theory whose characteristic matter distribution does not concord with observation (it breaks when the radial symmetry breaks, as in galaxy-galaxy mergers, lumpy galaxy clusters, and so on) is interesting but doesn't say much about astrophysics.
The preprint itself was the basis of a workshop talk on speculative physics, and the workship was literally titled in the form of a question ("What Comes Beyond Standard Models?")
FWIW, I had never before this heard of Bled Workshops in Physics, and I still don't know (after poking around in citeseer and the like) whether it is an event in Slovenia, or just named after Bled, Slovenia.
> hep-th/0710.1735
I don't understand why this is in hep-th rather than gr-qc as it is manifestly about a semiclassical model, with a peculiar form of quantum matter used to study gravitational collapse.
The paper is essentially an obituary for an idea for a toy quantum field on a classical curved spacetime that might work better than the simplest toy quantum field that has been in use since at least Hawking's 1974 work. The original work [hep-th/0205.319] introduces this toy model containing analogue to electromagnetism, and found that they could only form black holes under certain conditions. These additional complications, your linked paper's authors argue, aren't helpful even under those certain conditions, leading to things like naked singularities away from the horizon (p.20).
The paper's central purpose is to narrow the viability of this family of toy matter; in the authors' words (p.2.), "In this work we address the following question: Are there other static, spherically symmetric black hole solutions for the MTZ model, satisfying the dominant and strong energy condition between the event and cosmological horizon, besides MTZ1 and MTZ2? Using a combination of analytical and numerical methods we conclude that the answer to this question is negative." (In the very next paragraph they point out that MTZ2 has already been shown to be unstable with the addition of spherically symmetric masses, and that they will show that MTZ1 has the same problem).
The final paragraph of p.20 is pretty damning, and declares the low-energy-string-theory MTZ idea dead. ("M" is also one of the authors of the obituary). And so this raises my second question:
Why did you link this paper?
In my view does not support your statement that there is "a huge hole in black hole theory right now", but am certainly interested on what motivated your choice of that paper in the context of the questions tsegratis asked. Neither paper seems to go anywhere near answering those questions.
Lots of answers at link, most amusing one is:
> The total mass of the black hole must reside, completely, and only, in the self-energy of the curvature of spacetime around the hole!
> The answer to your question, then, is this: information about the mass of a black hole doesn't have to escape from within the black hole because there is no mass inside the black hole. All the mass is distributed in the field outside the hole. Therefore, no information needs to escape from inside
It seems the general answer is that fields and particles are not the same thing, and black holes can generate fields...
Since time stops within a black hole singularity, is entering one a good tip for escaping the end of the universe?
Below is some interesting background, on how a field is static, already defined at the creation of the black hole, and particles, if they happen, are just communicating changes in the field:
> A particle is an excitation of a field, not the field itself. In QED, if you set up a static central charge, and leave it there a very long time, it sets up a field E=kqr2. No photons. When another charge enters that region, it feels that force. Now, that second charge will scatter and accelerate, and there, you will have a e−−>e−+γ reaction due to that acceleration, (classically, the waves created by having a disturbance in the EM field) but you will not have a photon exchange with the central charge, at least not until it feels the field set up by our first charge, which will happen at some later time
> Now, consider the black hole. It is a static solution of Einstein's equations, sitting there happily. When it is intruded upon by a test mass, it already has set up its field. So, when something scatters off of it, it moves along the field set up by the black hole. Now, it will accelerate, and perhaps, "radiate a graviton", but the black hole will only feel that after the test particle's radiation field enters the black hole horizon, which it may do freely. But nowhere in this process, does a particle leave the black hole horizon
> On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ∼1.7 s with respect to the merger time.
So there is a delay between arrival of gravitational waves and accompanying gamma ray burst, but I couldn't tell you if that's purely because light travels slower than it would in a perfect vacuum, because the gravitational waves are generated before the gamma ray burst, or a bit of both. The GRB being less than two seconds long, I would guess they both happened at close to the same time, and it does have a speed difference.
Coming from an object 130 million light years away, 1.7 seconds is a very small difference in speed.
If there was something that didn't obey fundamental changes to spacetime itself we'd observe things like gravitational waves in a completely different location and time to their visual counterparts. We do not see any evidence of this. So for any theory that states a change in the fabric of spacetime itself you can guarantee that everything must conform to that change.
This is a handy feature, since when a high-redshift candidate event is detected by LIGO or Virgo, various telescopes can search the inferred location on the sky, looking for a trailing component. A neutron star-black hole merger, for instance, will have a such a component. So will a star falling apart in proximity to a black hole (a "tidal disruption event"). The spread for closer events isn't so big: detection of the LIGO/VIRGO G298048 (sourced about 140 million light years away, so very low redshift) event's gamma rays trailed by about about 1.7 seconds after the gravitational waves.
We can draw a direct comparison with neutrinos. Although they are not massless, and thus obey a different wave equation, they are very very very light, so we in multi-messenger astronomy we can treat them as if they effectively move at the speed of light. (In fact, supernova multi-messenger astronomy is a strong constraint on the difference between the speed of light and the speed of neutrinos).
Neutrinos also couple with gas and dust very very weakly, and so a neutrino signal and a gravitational wave signal will arrive at nearly the same time, with the electromagnetic components arriving later.
> ... curvature ... curvature of spacetime ... Gravitational fields themselves influence the propagation of gravitational fields
While you're right that different solutions of the Einstein Field Equations of General Relativity do not superpose linearly (around a Schwarzschild black hole, a very low-mass particle behaves very differently from a one with enough mass to have a gravitational self-force: https://arxiv.org/abs/0902.0573 for gory details) it's probably easy to be misled by mixing a field view of General Relativity ("GR") with a geometry ("curvature") view.
We can take an effective field theory view of GR and say that there is some chosen background (e.g. Minkowski spacetime) that is perturbed by a non-rotating point mass, the combination of the two (Minkowski + perturbation) generates the Schwarzschild spacetime. We can then add another mass, a second perturbation, and see what the combination of three (Minkowski + perturbation_1 + perturbation_2) does. This is the approach of https://en.wikipedia.org/wiki/Post-Newtonian_expansion and as can be seen in the diagram on that page, it is only valid when the two masses are fairly far apart. It is hard not to think of the perturbations as fields in the sense that you seem to be thinking about. Unfortunately this has its limits. As you bring the masses closer together (increasing compactness, moving downwards on the Y axis in the diagram), obviously wrong predictions tend to creep in, destroying one's confidence in the idea that in a system with multiple gravitating masses, each generates its own independent gravitational field which can somehow be combined (or which somehow propagate through some background).
In the most popular General Relativity reference book, Misner, Thorne & Wheeler's Gravitation, the authors discuss the expression "prior geometry", meaning some aspect of the curvature which is externally fixed or non-dynamical. General Relativity is a theory with "no prior geometry", and they make a brief argument about this. While some decades later we are much better with post-Newtonian expansion approaches (which do fix a prior geometry, which is then studied using perturbation methods), and can ignore "no prior geometry" as much more than a slogan in many cases, unfortunately we cannot do so for all of them.
For highly relativistic problems (objects moving near c; "escape velocities" near c), one must resort to the full theory of General Relativity, either solving the exact form, a good approximation (see https://pos.sissa.it/081/015/pdf), or a numerical solution where neither of the previous two forms are known or to "hide" divergences in analytical approaches.
Additionally, for speculative modelling of highly relativistic systems we may wish to require that the model enjoy the manifest https://en.wikipedia.org/wiki/Background_independence of the full theory of General Relativity, which in a practical sense means that all possible observers will agree on the point-coincidences of the system independent of the choice of observer's system of coordinates or relative motion (object "A" and object "B" are in contact at the same point in spacetime for all observers; you don't have fast-moving observers calculate them never to have been in contact; you don't have rotating observers calculating them as never-in-contact; you don't have observers in deep space disagreeing with planet-bound observers about whether "A" and "B" come into contact, etc).
Approximations instead fix some aspect(s) into a background, and in some strongly relativistic systems, one may have to introduce counter-terms ("ghosts") for families of observers that are not ideal Eulerian observers within that background.
(Einstein has a good argument about this in Chapter XXXII ("The Structure of Space According to the Theory of General Relativity") in his 1934 book, https://www.ibiblio.org/ebooks/Einstein/Einstein_Relativity.... whose "not-even-quasi-Euclidean" argument is extended in Appendix 4 and accompanied by a further fourteen pages as Appendix Chapter 5 ("Relativity and the Problem of Space") in the (not-as-freely-available) 2nd edition https://doi.org/10.4324/9780203518922 )
… or something like that.
It's a matter of perspective. Our Solar System's mass is 98% in the Sun. Earth is tiny and small and, as a GR object, is moving very slowly, and that only according to how its particles were set in motion at the beginning of time.
As others have said, gravitational lensing is a real thing, but that is a cosmological effect, and we are completely at the whim of the Initial Conditions for these opportunities.
(If there are real engineering applications for GR, especially in optics, I would be delighted and grateful to learn more!)
Large-frame optical Sagnac gyroscopes for precision geodesy:
https://www.frontiersin.org/articles/10.3389/fspas.2020.0004...
And some detail on the GINGER project, "Sagnac Effect, Ring Lasers, and Terrestrial Tests of [post-Newtonian] Gravity" (clarification mine), https://www.mdpi.com/2075-4434/3/2/84/htm
I imagine there is some literature on higher order modes in dispersion compensating fibre spools placed over underground flows (magma, water) but don't really have time to think about what decade practical engineering problems might emerge.
Of possible interest to you, quoting preface of following: "These few words should make it clear that quantum optics, experimental gravitation and measurement theory are not nearly as far apart as one might first have thought. However, there has traditionally been little contact between physicists working in these various fields." (which is a little less true now because of e.g. LIGO) https://link.springer.com/book/10.1007%2F978-1-4613-3712-6
Next, I'm pretty sure that the emissions spectra of galactic magnetars (https://en.wikipedia.org/wiki/SGR_1935%2B2154 , one of Arecibo's last big detections, §2.1 of https://arxiv.org/abs/2103.06052v1 ) are far from the cosmological scale (see https://arxiv.org/abs/1507.02924 n.b. figure 24).
> gravitational lensing ... is a cosmological effect
Also pretty sure the Magellanic Clouds, other non-naked-eye Milky Way satellites, and some galactic targets aren't "cosmological", https://en.wikipedia.org/wiki/Gravitational_microlensing#Obs...
Finally, it strikes me as unfair to to invoke Initial Conditions as a way to discount the relevance of gravitational observations. What, if not Intial Conditions, determines the frequency of your HeNe laser? Where did the neon in particular come from? (spoiler: https://en.wikipedia.org/wiki/Neon#Occurrence) And that helium is mostly a cosmological effect! ("The vast majority of helium was formed by Big Bang nucleosynthesis one to three minutes after the Big Bang. As such, measurements of its abundance contribute to cosmological models.")
Strong evidence that God loves helium, and considers it a good party trick to have some on hand! But I always thought He was generated from fusing two H into an He in a Sun somewhere.
Do note that current quantum field theories do not work in curved space-time, so this may turn out to be wrong in certain crucial ways.
In general curved spacetimes. But that includes a lot of obvious unphysicality.
Modelling our universe, QFT in CS (the subject of textbooks, after all, like Birrell and Davies) works just fine away from strong curvature, all of which as far as we can tell is shrouded behind an event horizon or not-practically-observable in the very early universe.
You don't have to take my word for it. See https://en.wikipedia.org/wiki/Robert_Wald 's first three slides (after the title slide) at http://gravity.psu.edu/events/abhayfest/talks/Wald.pdf )
tl;dr: it is a fine effective theory, but not a good candidate for a fundamental theory.
(Also in your first paragraph you are implicitly carving up spacetime in to space + time, and not taking that into account in what you write about "straight lines". However, you've got one part right namely (paraphrasing the start, up to the second comma, of your parenthetical) the spacetime interval of a null geodesic).
“Take the case where a massive object is put into a superposition of two possible locations at the same time. General relativity says that any object with mass should bend the fabric of space-time. But what if that object is in a superposition? Is the geometry of space-time also in a superposition?”
I don’t have a PhD in anything let alone physics, but it seems to me that answering the above question could potentially lead to a reformulation of GR in a way that gracefully incorporates quantum mechanics, which is worth getting excited about.
But yes, you’re correct that the nuance is lost on me. Still, there seem to be plenty of people who find it interesting.
Seems like there is a lot of theory discussions around the Internet but not seeing any experimental evidence one way or the other in the first few results.
The curious thing in my opinion is how this will effect quantum computing. If gravity causes decoherence, then it is likely difficult to maintain coherence in large qubit devices that aren't in microgravity.
The first problem is that a quantum theory of gravity is not straightforward. It's not "just" a spacetime with superposition, it probably has an even richer structure, the way QED has a richer structure than an EM field with superposition. And from the little hints we have it might have "spin 2" representation, and thereshould be some quantum very complicated field that acts like the metric GR field at low energies. But not only there are many possibilities for that, they are also very complicated, basically untreatable, or have infinite degrees of freedom in their definition itself.
The second problem is that there is no current way of experimentally probing such behavior. You say put a massive object in superposition, but to have observable effects you need to have so massive an object that is tens of orders of magnitude above "impossible".
This experiment is nice but it probes "just" the gravitational field of the Earth (a ~10^25 kg object). It is very nice for accurate time measures, and maybe for measuring gravitational fields, it comes nowhere near to probe quantum gravity effects, just quantum effects coupled to classical gravity (classic in the sense of GR but not quantum)
For example, I get entanglement. I can get answers to questions like "Is FTL comm possible? No." or "What is a practical application for entanglement? Quantum radar - sorting your initial emission from jamming." etc.
This though? Just too abstract (for me).
On the other hand, when they publish an economics article here, with the interests and the rates and the valuations of the options and whatnot, I understand almost nothing. I can't force myself to care about those things.
[1] I recommend kurzgesagt, Sabine Hossenfelder and PBS Space Time
That said, I do think that in general popular science articles are pretty bad, and laymen are mostly getting confusion out of them. And I do (probably?) agree with you that the people upvoting these submissions are pretty confused and I am not sure why are they upvoting them. Personally, I wouldn't post such articles here but as long as people seem to happily engage with one another I don't see any problem with such articles.
To a first approximation there are the same proportion of people knowing physics here (arguably an offtopic subject) as there are people knowing real type theory (definitely an ontopic subject), so the niche aspect of it can't be a deciding factor on what to post.