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sPHENIX uses software that we’ve worked on at CERN to do some of their reconstruction!


I get what you’re saying, but the measurements are real. In some sense they are the truth.

In the article this refers to the finding that the quark is more complex than three valence quarks.

The measurements indicating that the three-quark-model is incomplete are overwhelmingly conclusive, so some degree of certainty in the language is warranted in my view.


Neutrons are just as complex, they’re much harder to study though.


If i remember correctly Feynman said in one of his lectures that we know the mass of the electron with much greater precision than the proton, which may mean that it electrons are easier to study. I don't know if this is still true though.


Oh yes and so much so! Electrons are point-like (not composite like a proton) and interact only electroweakly (not strongly).


> point-like

Oh, your going to love this theory.

https://fondationlouisdebroglie.org/AFLB-222/MARK.TEX2.pdf

In summary, There is a way to model electrons as a twisted self enclosed em field.

A decent digest summary of the paper is this video

https://www.youtube.com/watch?v=hYyrgDEJLOA (Huygens Optics: Are Electrons made of Light? )


And neutrons are neither.


If it was possible to build a direct neutron accelerator/collider, I suspect we'd get some new physics pretty quickly.

Analysing hand-me-down neutron events from indirect collisions isn't quite as useful.


At ISIS (Oxford neutron source)…

Spallation generation: High-energy protons (~800 MeV) hit a heavy target, releasing a wide spectrum of fast neutrons up to hundreds of MeV. These are then moderated down to useful energies for experiments.

It’s not the LHC, sure. But I don’t see any reason (apart from “why bother”) why they can’t do spallation in Geneva. OK maybe there’s a cooling problem…


Spallation is the easy part

But neutrons can't go around a tube being guided by magnetic fields


Well my point is that the energy of the spallation neutrons is monotonically related to the energy of the protons hitting the Tungsten target ... although somewhat lower. I would consider these 100s MeV partiles to be (quite) high energy in contrast to the thermal neutrons alluded to elsewhere. Sure the spallation is lossy, but the result is still pretty high. And the physics is somewhat different with neutron experiments vs. protons... iiuc


There absolutely are direct neutron experiments, but they are much lower energy and have a different focus, partly because neutrons being neutral means they’re very hard to accelerate.

There’s an ultra cold neutron source at Paul Scherrer that is used to measure if the neutron has an electric dipole moment. This is complementary to high energy experiments.


Neutrons are not that different from protons. The decay from neutrons to protons is pretty well understood, and there’s no reason to think that the nature of quark/gluon interactions in a neutron are significantly different from those in a proton. What kind of new physics are you imagining we’d get?

Of course more experimental data is a good thing, but in this case it doesn’t seem obvious that it would lead to anything really new.


Why do you say they're "pretty well understood" when there's been a long-standing unresolved discrepancy between lifetime measurement techniques?


I think they mean that what happens when a neutron decays is well understood. One of the neutron's down quarks change to an up quark, facilitated by a virtual W boson with negative charge. The W boson is very unstable and immediately decays into an electron and an electron anti-neutrino, both of which are ejected leaving behind the former neutrino which is now a proton because of that quark change.

When that happens is less understood, hence the discrepancies you mentioned.


The same QCD theory that's used to model the proton models the neutron. Theoretically, our understanding of both is on the same footing.

The comment I replied to talked about "new physics". That's a term that's used in physics to describe physics beyond the Standard Model. Better experimental data about neutron internals could certainly help constrain the neutron lifetime, but that would be likely to be experimental constraints on existing physics, not new physics in the sense that the term is normally used.


Didn’t they just drastically increase the price for non US citizens? I think it almost went up by 10x


I appreciate the opinion, but that precludes it from being used in repos that are not jj-first and happen to use submodules.


I got into jujutsu recently for the mega merge workflow.

The only thing I’m missing now is support for git submodules, especially when working with workspaces.

This requires me to keep using git worktrees with collocated jj in each of them, which is suboptimal.


Does jj’s own workspaces not help? I don’t use submodules so I don’t know.


Is selecting text in the PDF supported? I can’t get that to work in iOS Safari.


Text selection broken on Mac OS Safari as well. Worked in Chrome on Mac OS.


So far whenever jujutsu came up I didn’t find its features that convincing relative to git.

I have to say however that the mega merge workflow seems intriguing and might in fact be a solution to having to serialize my work like I do in git for now.

I think I’ll look into that.


What always disqualifies these projects for me is the fact that they need to use a headless browser to export to PDF. PDF export is the primary feature I need from these, and it’s a shame the export mechanism is still this slow and unreliable.


I found with that revealjs slides can be exported to pdf via their tools menu, and print it. It worked on Firefox. True that it’s a manual step. But no need to rely on a headless browser as soon as you don’t want to script it.

https://quarto.org/docs/presentations/revealjs/presenting.ht...


Yea.

Having intentionally stayed away from going down the PDF rabbit hole, but now confronting it again recently … what’s the deal with how sparsely populated the space is with solid and (relatively) light weight rendering solutions/back-ends?

Am I missing something or am I right in thinking that there’s a kinda pandoc/FFmpeg shaped hole in the document tooling space that no one wants to (or can’t) fill? Where tex and chrome based solutions are arguably just too heavy for a number of needs but all we really have?


The problem is that Markdown is not really a markup language, since it only defines the content and structure, but has no way to specify how it will be displayed. To go from content (Markdown) to rendered presentation (PDF) you need a proper markup languaje (HTML/Tex) to be able to specify its layout.


The reason it's hard to render straight from Markdown isn't because it's not a markup language like html - because Markdown is just syntactic sugar for a subset of html. Because of that, it's usually easier to just use the abundant html tooling to render it. The problem is that html needs CSS to render nicely - and any tool used to render CSS+HTML is almost by definition a browser engine.


Exactly, I would've hoped someone could come up with a way to render markdown directly into a PDF, without roundtripping via tex and having to handhold the styling process in the way that's required now.


This is why I still use beamer and pandoc.


This is a fantastic analogy!


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