Hacker News

Top stories

Live mirror
30 storiesupdated just nowView source snapshot
  1. F-Droid 2.0: A New Chapter for Android Freedom(f-droid.org)
    64comments
  2. GitHub has not removed malicious imitation software after 3 weeks(successfulsoftware.net)
    19comments
  3. Dynamic Abliteration: Non-Destructive Refusal Suppression via Engram Steering(blog.madhukaraphatak.in)
    30comments
  4. The science of Monkey Island: can grog dissolve a metal mug that fast?(jgeekstudies.org)
    15comments
  5. Two-tier encryption in the UK(macanorak.com)
    225comments
  6. I Have a Confession: I Built This Site with AI – Please Forgive Me(dynamicallytyped.org)
    24comments
  7. Enjoy Every Sandwich(bradmontague.substack.com)
    55comments
  8. Nokia Design Archive (2025)(aalto.fi)
    86comments
  9. Linux support is coming to Snapdragon X2 Series(qualcomm.com)
    237comments
  10. LinkedIn wins court order blocking mass scraping of user data(therecord.media)
    8comments
  11. QR Codes That Route to the Appropriate App Store(matthuggins.com)
    5comments
  12. Ideas on modernizing the open-source desktop(lwn.net)
    381comments
  13. RAM: the forgotten history (2024)(coredump.cx)
    2comments
  14. ArXiv receives multiyear commitments to support it as an independent nonprofit(arxiv.org)
    37comments
  15. WaveDigger: Dig into wireless signals to discover their physical locations(github.com/christianrowlands)
    2comments
  16. What Is RLCD? The Secret Behind Jev(di-zhang-llm.github.io)
    3comments
  17. When the Debugger Lies(danielmangum.com)
    16comments
  18. The newest ESP32 can run Linux and it's getting close to a Raspberry Pi(xda-developers.com)
    69comments
  19. VSCode's SSH Agent Is Bananas (2025)(fly.io)
    186comments
  20. Coulomb's law remains tricky to test at home(chillphysicsenjoyer.substack.com)
    9comments
  21. Contrastive Language Models(contrastive-lm.notion.site)
    40comments
  22. The "Windows XP Box" (2003)(mini-itx.com)
    43comments
  23. The Year of Internal Tools(geocod.io)
    12comments
  24. Fixing the Portobello Police Station Clock(pointinthecloud.com)
    112comments
  25. Humans Are Reading Your ChatGPT Chats, Lawsuit Claims(openclassactions.com)
    7comments
  26. Virtio-nvgpu: Near-native Nvidia GPU access inside a KVM guest(github.com/nestrilabs)
    59comments
  27. Hackers influence ChatGPT and Gemini to direct users to scam centers(medium.com/arielsimon)
    33comments
  28. Best LLM for every budget, updated daily(terrydjony.com)
    83comments
  29. Why 'What's Opera, Doc?' looks like that(animationobsessive.substack.com)
    22comments
  30. Owners mourn spoiled food after firmware update bricks Samsung smart fridges(arstechnica.com)
    204comments

Coulomb's law remains tricky to test at home

14 pointsby 2d agochillphysicsenjoyer.substack.com
9 comments
1h agoHN ↗

Good idea, you could do a monte carlo method where you throw many packing peanuts at the cat (or many cats!) and count how many stick, divide by how many you threw, et voila

1h agoHN ↗

But it's not at all obvious to me why the exponent a is 1 in nature

i think we can rule out any exponent just by dimensional analysis if you allow powers of q, then K has ambiguous units. Same reason you cant exponentiate unitful quantities

More specifically I think we can rule out even exponents by anti-symmetry of charge. That is q^2n = (-q)^2n which know is ruled out by experiment.

1h agoHN ↗

Why would the universe care about dimensional analysis? Besides, the outside constant would do the unit conversion from whatever the right-hand side produces to units of force.

1h agoHN ↗

you have free constant k in front of the equation

any dimensional analysis gets consumed by its unknown dimensionality

---

q^2n = (-q)^2n which know is ruled out by experiment.

doesn't mean equation can't be using absolute values ("number of electrons/protons") and just applying needed sign at the end

1h agoHN ↗

Supposedly, one way to make two equal charges is to charge one thing and then put it in contact with the other thing, so that the charge splits by symmetry. But then how would we check that indeed we have two equally charged things?

same as with making guaranteed flat surface - you make 3 and measure each pair

33m agoHN ↗

How do you make 3 equal charges by splitting a charge in such a manner?

1h agoHN ↗

It's probably easier to verify Gauss's Law, which then gives you Coulomb's law for free.

Direct verification of inverse square laws is hard! For electromagnetic interactions (ie Coulomb's law) you can use scattering. If you want to do a static experiment (Coulomb's Law the hard way or gravity) you probably need a torsion pendulum experiment. AFAIK the best in the world at that are at UW in the Eöt-Wash group: https://www.npl.washington.edu/eotwash/torsion-balances

53m agoHN ↗

Could you use an electromagnet and a metal ball to create a fixed charge? If you change the current in the electromagnet, that would change the intensity of the magnetic field. With the metal ball fixed in place nearby and a careful curve for the change of current, you could potentially have a constant charge remaining on the ball.