I'm out of touch and 5 years old, so please someone explain to me, but I thought the galaxies were bound together by divets in spacetime based on their mass dictated by the Higgs field. Now its dark matter binding the galaxies together?
Biggest dark matter detector spots a single weird particle
141–150 of 154 posts
Re: Biggest dark matter detector spots a single weird particle
#142i have zero knowledge of physics, but I just can't believe something like dark matter exists. My intuition is that some math just isn't correct and falls apart at the scales of the observable universe. No idea what equations are used for getting to the reslut of having 85% unexplained matter in the universe, but I really assume there's just a constant missing or our math in general just inaccurate or not considering…
> I just can't believe something like dark matter exists. That's a lot like a blind person saying they can't believe light exists. It takes only a small amount of knowledge of physics to understand why and how dark matter might be possible, even likely. So small, in fact, that I can describe it in this comment. The tl;dr is that all the senses you experience - sight, touch, smell, taste, and hearing - depend on the e…
>it could just have a very small degree of interaction that we can't easily detect, which is what the OP experiment is counting on.
It's an open question, right, whether dark matter has no interaction or just very little interaction with normal matter? If there's none, this experiment will detect nothing but noise.
I'm confused why, if dark matter exists and has mass (since it interacts gravitationally), there's no noticeable missing results from high-energy events that create particles. Shouldn't dark matter particles be generated by, say, cosmic ray collisions? Or black hole decay?
Re: Biggest dark matter detector spots a single weird particle
#143I read their preprint[1] and they did a thorough job. They investigated a number of the things I'd suspect if I were looking for mis-reconstructed events or weird backgrounds. So it's certainly interesting! That said, particle physics history is full of 3 sigma particle "discoveries" that disappeared with more data. They're collecting more, so hopefully we'll learn more in a few more years. [1] https://lz.lbl.gov/wp-…
> That said, particle physics history is full of 3 sigma particle "discoveries" that disappeared with more data. The idea is that because 3 sigma means a ~1/1000 chance of the thing being explained by random chance, 1 in 1000 experiments will produce a bogus 3 sigma result, and we do many thousands of experiments.
and also because a result always has the caveats of "if we did our experimental design and math right". A 1/1000 rate of experimental/code design errors will double the number of incorrect 3 sigma results.
Re: Biggest dark matter detector spots a single weird particle
#144Earlier quoted context omitted.
> I just can't believe something like dark matter exists. That's a lot like a blind person saying they can't believe light exists. It takes only a small amount of knowledge of physics to understand why and how dark matter might be possible, even likely. So small, in fact, that I can describe it in this comment. The tl;dr is that all the senses you experience - sight, touch, smell, taste, and hearing - depend on the e…
>it could just have a very small degree of interaction that we can't easily detect, which is what the OP experiment is counting on. It's an open question, right, whether dark matter has no interaction or just very little interaction with normal matter? If there's none, this experiment will detect nothing but noise. I'm confused why, if dark matter exists and has mass (since it interacts gravitationally), there's no n…
> It's an open question, right, whether dark matter has no interaction or just very little interaction with normal matter? If there's none, this experiment will detect nothing but noise.
Correct. What this experiment (LUX-ZEPLIN) is looking for is the effects of xenon nuclei being "bumped" - recoiling - due to something undetectable. It doesn't matter what interaction mediates the recoil - it could even be a so-far-undiscovered interaction. They're just looking for evidence of the recoil happening. But if the only interaction is gravity, they won't detect anything, since gravity is too weak for us to detect the effects of at that scale.
> I'm confused why, if dark matter exists and has mass (since it interacts gravitationally), there's no noticeable missing results from high-energy events that create particles.
Particle physicists actively look for this, e.g. in reactions in particle accelerators. But not finding evidence of that only places constraints on how strongly dark matter can couple to ordinary matter, it doesn't rule it out.
> Shouldn't dark matter particles be generated by, say, cosmic ray collisions?
Not necessarily. Just being energetic doesn't guarantee anything. There's a bit of a chicken-and-egg issue here: without knowing more about dark matter, we can't predict what reactions might produce it. That's why experiments like LUX-ZEPLIN make as few assumptions as possible - all it requires is that some mechanism for energy transfer from dark matter to matter exists.
> Or black hole decay?
Black hole decay has never been observed. Since it's purely theoretical, no matter how well-justified it is, it doesn't really help in the search for dark matter. There's no reason that Hawking radiation couldn't include dark matter, in fact if dark matter exists it probably would, but we have no way to detect that.
Even if say black hole collisions (which have been indirectly observed) produced dark matter, we wouldn't really have any way of detecting it at the distances in question.
Re: Biggest dark matter detector spots a single weird particle
#145Earlier quoted context omitted.
The mainstream TV news report that I saw about this ended with a comment about how we should continue to fund this detector. Made me wonder if the nature of this release involved forces other than purely scientific ones. Apparently funding has already been cut for the successor to the LUX-ZEPLIN detector.
Particle physics is not a particularly large community. There is a hand-countable number of experiments like this, and the folks working on each of them know the folks working on each of the others. The collaborations executing each experiment are comprised of scientists employed by multiple independent institutions, both public and private, typically across national borders. Internally, the collaborations have a dem…
I'm not suggesting distortion or misrepresentation of the published result. The actual preprint is quite clear on the nature and limitations of the result, and there's no reason to think that what they're reporting didn't happen as described.
However, the context here is that the DOE has already paused funding for the experiment's successor, XLZD, for an unspecified amount of time which realistically, is probably going to depend on the next US presidential election. At the same time, the DOE encouraged the LZ project to develop scenarios for continuing to operating beyond its current end date of 2028.
Now, here's what the NBC Bay Area report I mentioned[0] ended with:
> "All the more reason, they say, to keep these machines running. [...] They'd like to keep the machines running, they wanna keep doing this research, they're applying for funding now, so fingers crossed, we'll have more updates on this [...]"
The media attention this received was not the organic result of some journalist noticing the preprint or the talk at TeVPA in Japan. There was a major wave of synchronized official press releases, coinciding with the TeVPA talk, from Berkeley National Lab[1], Brown University[2], SLAC[3], Brookhaven[4], Stanford[5], University of Sydney[6], and others including UMass Amherst and Imperial College London.
Now, these institutions are all involved in the collaboration somehow, so it makes sense that they would coordinate press releases for a major result. The question is whether this result warrants such treatment. It's a single event at 2.6 sigma global significance. Promoting it in this way was a choice, and I'm pointing out that it seems quite possible - in fact I'd say extremely likely - that that choice was made with the funding situation top of mind.
[0] https://www.youtube.com/watch?v=bf3aW0xTEEc
[1] https://newscenter.lbl.gov/2026/09/01/lz-sees-surprising-res...
[2] https://www.brown.edu/news/2026-09-01/lz-dark-matter-results
[3] https://www6.slac.stanford.edu/news/2026-09-01-lz-sees-surpr...
[4] https://www.bnl.gov/newsroom/news.php?a=123133
[5] https://news.stanford.edu/stories/2026/09/dark-matter-detect...
[6] https://www.sydney.edu.au/news-opinion/news/2026/09/03/lz-ex...
Re: Biggest dark matter detector spots a single weird particle
#146I read their preprint[1] and they did a thorough job. They investigated a number of the things I'd suspect if I were looking for mis-reconstructed events or weird backgrounds. So it's certainly interesting! That said, particle physics history is full of 3 sigma particle "discoveries" that disappeared with more data. They're collecting more, so hopefully we'll learn more in a few more years. [1] https://lz.lbl.gov/wp-…
This sort of thing is really useful for helping people to understand what the purpose of scientific publication is. It's not about presenting finished products to society, it's more like a Discord where you communicate new findings with other authors. Often the reason for a communication is because you found something weird, and you want other people to know about it so they can help you confirm or rule it out as bad…
People who stare down noise to see the truth.
Re: Biggest dark matter detector spots a single weird particle
#147i have zero knowledge of physics, but I just can't believe something like dark matter exists. My intuition is that some math just isn't correct and falls apart at the scales of the observable universe. No idea what equations are used for getting to the reslut of having 85% unexplained matter in the universe, but I really assume there's just a constant missing or our math in general just inaccurate or not considering…
Here's a serious question: If you start with "I don't know anything about what I'm going to talk about...", why even post?
I wouldn't go into a neurological medical thread, and post "I'd guess it doesn't even exist" as a solution for Alzheimer's. But you just did the same, analogously.
Re: Biggest dark matter detector spots a single weird particle
#148Earlier quoted context omitted.
Or this[2] 2007 Science paper on ultra high energy cosmic ray source candidates ("anisotropy") that we had to retract because significance started dropping almost the day the paper was approved. It was a fascinating experience as a junior member to follow the collaboration internal conversation and investigation on this, because a lot of extremely principled scientists were clearly deeply worried about losing their h…
Wow haha, that is a lot of authors! Never seen this before!
As another comment points out: that's nothing compared to high energy/particle physics!
The Pierre Auger Observatory certainly is a large collaboration for the astroparticle physics domain though. It's a big international collaboration.
Quick anecdote: my name (S Mueller) is not on that paper's author list because we had a rule that you had to be in the collaboration for a year before getting authorship. You stayed on for a year after leaving. Very reasonable! At the time I was nonetheless a bit bummed about missing out on the big Science paper. I guess I'm on the retraction though ;)
Re: Biggest dark matter detector spots a single weird particle
#149> Such behavior could require dark matter to be more complicated than just a single new type of particle. For example, the dark matter particle might have some internal structure, like an ordinary atom, so it would only interact if hit hard enough to excite it to a higher energy internal state I get a little shiver imagining that the dark matter might be something like ordinary atoms. Imagine that other 85% of the un…
I've heard this referred to as a "dark sector", or "hidden sector": https://en.wikipedia.org/wiki/Hidden_sector The scary thought is that, were it true that there is voluminous richly-interacting dark matter, we would be the actual dark sector.
On this the same line of thoughts, so far we have 0 proof that all dark matter is _the same_. We observe gravity effects but IIRC they very little tell us about their own homogeneity. We very well could have a few parallel sectors, one of which is ours.
Re: Biggest dark matter detector spots a single weird particle
#150Earlier quoted context omitted.
Particle physics is not a particularly large community. There is a hand-countable number of experiments like this, and the folks working on each of them know the folks working on each of the others. The collaborations executing each experiment are comprised of scientists employed by multiple independent institutions, both public and private, typically across national borders. Internally, the collaborations have a dem…
I'm not suggesting distortion or misrepresentation of the published result. The actual preprint is quite clear on the nature and limitations of the result, and there's no reason to think that what they're reporting didn't happen as described. However, the context here is that the DOE has already paused funding for the experiment's successor, XLZD, for an unspecified amount of time which realistically, is probably goi…
Thanks for clarifying, and my apologies if I came off as argumentative --- what you _are_ suggesting makes sense and is a reasonable thing to wonder about.
But I don't see anything particularly strange or coordinated is happening. From the collaboration's perspective, it's quite stressful having this event. They've already unblinded, so it would be unethical to do anything other than report what they found. If they publicize it and it's a mistake, then that's a big blow to their credibility. But if they withhold it and it's real, then they miss making the discovery and/or bias their future analyses on larger datasets without disclosing that to the community. So they are in a tough spot, and are safest to just tell the world what they saw.
This is getting media attention because it would be a big deal to the general public if this ends up being a real. Someone in the field wouldn't claim that it's real, but the possibility is catnip to folks looking for a sensational headline. That the press releases are synchronized in time is because the result was just released right now and they're all doing their commentaries right away --- for something like this, each institution independently negotiates a release with the local researchers who are involved. They all promise to wait until the result is officially released, out of respect for the scientific process, like you say, but the different institutions aren't coordinating with each other. They're just all respecting their own researchers.
Is a 2 or 3 sigma fluctuation worth a lot of press? Personally, I don't think so. But we don't know if it's a fluctuation yet, and no institution is going to pass on having made it clear, if this does turn out to be real, that they were involved.
All that being said: I would very much like these folks to continue to receive funding. They are professional and do excellent work, as demonstrated here.