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maxnoe

1,386 karma · joined February 28, 2017

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maxnoe··on On caring for user data: NeoVim caused Vim undo files to be deleted
> The application must be able to restore or regenerate the data

That's a break of the contract then, right? The application was not able to regenerate or restore.

Cache is the wrong place for a persistent undo file.

maxnoe··on Cherenkov Radiation
Cherenkov radiation is UV to visible blue light, it travels at the speed of light in the medium, which is lower than the speed of light in vacuum.

Only the charged particle that induces the emission travels faster than the local speed of light.

maxnoe··on Cherenkov Radiation
Astronauts have reported having difficulty sleeping due to cosmic-ray-induced Cherenkov flashes in their eye bulbs.
maxnoe··on Cherenkov Radiation
Very shortly summarized, only if the particle is faster than the local speed of light, you get constructive interference between many atoms that were polarized by the moving particle.

For a slower than light particle, you also get emission, but it is completely random and thus does not give the well defined emission in a cone of Cherenkov radiation.

For a faster than light particle, the spherical suddenly line up to form a cone:

https://en.wikipedia.org/wiki/Cherenkov_radiation#/media/Fil...

maxnoe··on Cherenkov Radiation - traveling faster than light
Neutrinos are neutral particles, they do not carry an electromagnetic charge. They thus do not cause any Cherenkov light themselves.

What Neutrino detector measure is the Cherenkov light emitted by secondary particles that are created when a Neutrino interacts with the matter inside the detector.

E.g. a muon Neutrino reacts with a water molecule producing a muon, which is a charged particle and thus emits Cherenkov light.

maxnoe··on Cherenkov Radiation
The article has a section about what it can be used for, but only mentions the uses of the IAEA.

Of course I am biased because I work in the field, but the by far most wide reaching application of Cherenkov radiation is in the detection of high energy particles, particularly in astrophysics.

- Imaging Atmospheric Cherenkov telescopes detect the Cherenkov radiation emmited in the atmosphere when a high energy cosmic ray or gamma ray creates an air shower

- Water Cherenkov Detectors detect Cherenkov light when the secondary particles of these air showers reach water tanks on the ground

- Neutrino telescopes like kamiokande, Icecube and km3net detect Cherenkov radiation in water or ice produced by secondary particles produced by the rare interactions of Neutrinos in their detector volumes

Modern, high energy astrophysics is all about detecting different kinds of Cherenkov radiation and then reconstructing the original particle properties.

maxnoe··on CERN Transitioning to Debian After Being a Longtime RHEL Institution
For industrial computers and other embedded systems.

Computing AFAIK is very much still based on RHEL-based distros, Alma Linux specifically.

https://linux.web.cern.ch/

maxnoe··on Future euro banknote design proposals
Because he composed the anthem?
maxnoe··on New Framework Desktop Option with AMD Ryzen AI Max+ Pro 495 and 192GB Memory
Who blatantly ripped that off from Karl Marx...
maxnoe··on 'Complex numbers are not needed for quantum mechanics'
> The square root of -1 doesn't correspond to any quantity you could count or measure directly (you can't have negative one apple, for instance)

That must be the worst explanation of complex numbers I ever read. It's not even remotely connected.

maxnoe··on No leap second will be introduced at the end of December 2026
Unix time does not count elapsed seconds in real time since 1970-01-01T00:00:00, this is a common misconception.

Unix time assumes a fixed number of seconds per day. 86400. If a leap second is inserted, either end of June or end of December, the day is 86401 seconds long.

There are different implementations for how your Unix time will behave 24 hours before to 24 hours after the leap second. A timestamp might just repeat during the leap second or the system changes the length of a second in a time range around the leap second introduction to make up the difference. This is called smearing.

A simple example is the elapsed time between these two timestamps:

    2016-12-31 23:59:50
    2017-01-01 00:00:10
Unix time differs by 20 seconds (assuming the system/library doesn't use smearing). But actually elapsed time is 21 seconds, since

    2016-12-31 23:59:60
was the last added leap second. This timestamp cannot be represented by Unix time (again assuming no smearing, with smearing you could).
maxnoe··on No leap second will be introduced at the end of December 2026
No, the current rules are being relaxed because with the current ones, a negative leap second _might_ happen in the near future.

It did not happen yet. No negative leap second that should have been inserted was skipped.

See this chart here:

https://en.wikipedia.org/wiki/DUT1#/media/File:Leapsecond.ut...

You can see the the positive leap seconds as jumps upward once the graph reaches around -0.5 s.

We were never close to reaching +0.5 seconds with a positive trend and we are still relatively far away from that.

maxnoe··on Incident with Pull Requests, Issues, Git Operations and API Requests
GitHub Incident again/
maxnoe··on Can You Find the Comet?
Imaging Atmospheric Cherenkov Telescopes, we detect optical light emitted by high energy particle Cascades in the atmosphere to observe cosmic gamma radiation.

The particles need the atmosphere to interact, Cherenkov light is only emitted in an optical medium and because it's optical light we measure we are affected by satellites. Not as strongly as optical telescopes though, because the air showers last for only tens of nanoseconds.

maxnoe··on Zed 1.0
One would be support for ligatures
maxnoe··on Can You Find the Comet?
Our telescopes actually need the (or at least an) atmosphere to function.

There are some classes of observatories, which you cannot build in space but which are still affected by satellites to some degree.

maxnoe··on Flickr: The first and last great photo platform
> This is where I usually insert that 3,000 year old Gandalf meme.

Elrond?

maxnoe··on Tip: Web requests should not be measured in Hz [Hertz]
Copying my comment from the other recent thread:

The authority on the definition of SI units is very clear:

> The hertz shall only be used for periodic phenomena and the becquerel shall only be used for stochastic processes in activity referred to a radionuclide

Usually, no radionuclides are involved in web requests.

https://www.bipm.org/documents/d/guest/si-brochure-9-en-pdf

maxnoe··on Vera C. Rubin Observatory has Discovered 11,000 New Asteroids
Keep in mind that our current instruments are not really sensitive to most exoplanets that would be interesting for a sci-fi setting.

Current instruments are mostly good at finding large planets around small stars, we are basically blind to earth-like planets around sun-like stars.

See e.g. https://www.nobelprize.org/prizes/physics/2019/queloz/lectur...

maxnoe··on SI Units for Request Rate (2024)
Please don't.

The authority on the definition of SI units is very clear:

> The hertz shall only be used for periodic phenomena and the becquerel shall only be used for stochastic processes in activity referred to a radionuclide

Neither is usually the case for requests.

https://www.bipm.org/documents/d/guest/si-brochure-9-en-pdf

maxnoe··on SI Units for Request Rate (2024)
Yes, the year has pi * 1e7 seconds

1e5 / 3.14e7 ≈ 3e-3, milli, not micro

maxnoe··on Am I German or Autistic?
Or as Stephen Fry put it: "Nature, Nurture and Nietzsche", very fitting here.
maxnoe··on OnlyOffice kills Nextcloud partnership for forking its project without approval
There is a section in the GitHub Readme of Eurooffice with a justification of the fork:

https://github.com/Euro-Office#euro-office-liberates-the-onl...

maxnoe··on Microsoft's "fix" for Windows 11
"Most companies still do not publish Linux builds for creative software"

There, fixed it for you.

It's not like Linux is the blocker here.

maxnoe··on Why I may ‘hire’ AI instead of a graduate student
Absolutely not. You could argue this for entry level lectures, but not at the PhD level. PhD is learning how to do original research, how could you separate teaching that from doing that?
maxnoe··on TeX Live 2026 is available for download now
Ever tried latexmk for the automation?
maxnoe··on Chained Assignment in Python Bytecode
But this exact example is different, because the critical step of mutation is missing.

The initial line is the same, but:

    a = b = random.random()
    a += 1
    a == b # False
Only because floats are immutable and thus an implicit copy is made and lists are mutable so the same mutable instance is pointed to by both names.

This talk still applies despite its age: https://youtu.be/_AEJHKGk9ns?si=q5HjMOM9QS3_bFzH

maxnoe··on String theory can now describe a universe that has dark energy?
Science never proves a positive.

You can only disprove.

The only way to prove a positive if there is a finite number of possibilities and you have disproven all but one. But even then, someone could conceivably come up with an alternate description that preserves the current understanding but makes additional predictions or is a simpler model making the same.

As Feyman said: "We can never know if we are right, we can only be certain if we are wrong".

maxnoe··on Astrophotography visibility plotting and planning tool
If you are more into doing this locally than using a Webservice, have a look at astroplan based on astropy.

https://astroplan.readthedocs.io/en/stable/

maxnoe··on Some ecologists fear their field is losing touch with nature
If it disagrees with experiment, it's wrong.

https://youtu.be/EYPapE-3FRw?si=LjSNyltYaVUY5bzX

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