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OpenCiv3: Open-source, cross-platform reimagining of Civilization III

https://openciv3.org/
391•klaussilveira•5h ago•85 comments

The Waymo World Model

https://waymo.com/blog/2026/02/the-waymo-world-model-a-new-frontier-for-autonomous-driving-simula...
749•xnx•10h ago•459 comments

Monty: A minimal, secure Python interpreter written in Rust for use by AI

https://github.com/pydantic/monty
118•dmpetrov•5h ago•48 comments

Show HN: Look Ma, No Linux: Shell, App Installer, Vi, Cc on ESP32-S3 / BreezyBox

https://github.com/valdanylchuk/breezydemo
131•isitcontent•5h ago•14 comments

Show HN: I spent 4 years building a UI design tool with only the features I use

https://vecti.com
234•vecti•7h ago•113 comments

Dark Alley Mathematics

https://blog.szczepan.org/blog/three-points/
28•quibono•4d ago•1 comments

A century of hair samples proves leaded gas ban worked

https://arstechnica.com/science/2026/02/a-century-of-hair-samples-proves-leaded-gas-ban-worked/
57•jnord•3d ago•3 comments

Microsoft open-sources LiteBox, a security-focused library OS

https://github.com/microsoft/litebox
302•aktau•11h ago•152 comments

Sheldon Brown's Bicycle Technical Info

https://www.sheldonbrown.com/
304•ostacke•11h ago•82 comments

Show HN: If you lose your memory, how to regain access to your computer?

https://eljojo.github.io/rememory/
160•eljojo•8h ago•121 comments

Hackers (1995) Animated Experience

https://hackers-1995.vercel.app/
377•todsacerdoti•13h ago•214 comments

Show HN: R3forth, a ColorForth-inspired language with a tiny VM

https://github.com/phreda4/r3
44•phreda4•4h ago•7 comments

An Update on Heroku

https://www.heroku.com/blog/an-update-on-heroku/
305•lstoll•11h ago•230 comments

I spent 5 years in DevOps – Solutions engineering gave me what I was missing

https://infisical.com/blog/devops-to-solutions-engineering
100•vmatsiiako•10h ago•34 comments

How to effectively write quality code with AI

https://heidenstedt.org/posts/2026/how-to-effectively-write-quality-code-with-ai/
167•i5heu•8h ago•127 comments

Learning from context is harder than we thought

https://hy.tencent.com/research/100025?langVersion=en
138•limoce•3d ago•76 comments

Understanding Neural Network, Visually

https://visualrambling.space/neural-network/
223•surprisetalk•3d ago•29 comments

FORTH? Really!?

https://rescrv.net/w/2026/02/06/associative
36•rescrv•12h ago•17 comments

I now assume that all ads on Apple news are scams

https://kirkville.com/i-now-assume-that-all-ads-on-apple-news-are-scams/
956•cdrnsf•14h ago•413 comments

Introducing the Developer Knowledge API and MCP Server

https://developers.googleblog.com/introducing-the-developer-knowledge-api-and-mcp-server/
8•gfortaine•2h ago•0 comments

PC Floppy Copy Protection: Vault Prolok

https://martypc.blogspot.com/2024/09/pc-floppy-copy-protection-vault-prolok.html
7•kmm•4d ago•0 comments

Evaluating and mitigating the growing risk of LLM-discovered 0-days

https://red.anthropic.com/2026/zero-days/
33•lebovic•1d ago•11 comments

I'm going to cure my girlfriend's brain tumor

https://andrewjrod.substack.com/p/im-going-to-cure-my-girlfriends-brain
30•ray__•1h ago•6 comments

Claude Composer

https://www.josh.ing/blog/claude-composer
97•coloneltcb•2d ago•68 comments

The Oklahoma Architect Who Turned Kitsch into Art

https://www.bloomberg.com/news/features/2026-01-31/oklahoma-architect-bruce-goff-s-wild-home-desi...
17•MarlonPro•3d ago•2 comments

Show HN: Smooth CLI – Token-efficient browser for AI agents

https://docs.smooth.sh/cli/overview
76•antves•1d ago•56 comments

Show HN: Slack CLI for Agents

https://github.com/stablyai/agent-slack
37•nwparker•1d ago•8 comments

How virtual textures work

https://www.shlom.dev/articles/how-virtual-textures-really-work/
23•betamark•12h ago•22 comments

Evolution of car door handles over the decades

https://newatlas.com/automotive/evolution-car-door-handle/
38•andsoitis•3d ago•61 comments

The Beauty of Slag

https://mag.uchicago.edu/science-medicine/beauty-slag
27•sohkamyung•3d ago•3 comments
Open in hackernews

Astrophysicists find no 'hair' on black holes

https://www.quantamagazine.org/astrophysicists-find-no-hair-on-black-holes-20250827/
63•rolph•5mo ago

Comments

pavel_lishin•5mo ago
> According to Albert Einstein’s general theory of relativity, the behavior of a black hole depends on two numbers: how heavy it is, and how fast it is rotating. And that’s it. Black holes are said to have “no hair” — no features that distinguish them from their fellows with the same mass and spin.

As far as I know, there's a third property that black holes have - electric charge. Would a sufficiently strong electric charge between two black holes be detectable, whether they both have the same charge, or opposing charges?

I suppose based on the article, the effects would only take places once the black holes got within 40km of each other...

momoschili•5mo ago
It has been proposed and is often studied in different contexts, but it seems unlikely that we will be able to measure it any time soon.
raverbashing•5mo ago
I think you might just need a comb and some pieces of paper
renewiltord•5mo ago
Judging by what the article says they can't be different

> In theory, there’s a third defining property: electric charge. But real, astrophysical black holes have negligible net charge.

fsmv•5mo ago
Black holes can have charge but a charged black hole would attract ions of the opposite charge strongly and would quickly neutralize. So it would be quite difficult to get a non-negligible charge on a black hole.
BurningFrog•5mo ago
So some very advanced and bored civilization could take black holes and shoot gigantic numbers of protons into it, and get a very positively charged black hole.

If you pump in enough charge that the electrical repulsion is stronger than the gravity attraction, you can then store them safely next to each other, for when you might need one.

marcosdumay•5mo ago
It also allows you to move the black hole around, somewhat freely.

It may be a very useful thing if it turns out that we can make small ones.

Terr_•5mo ago
> move the black hole around, somewhat freely [...] small ones

At the risk of spoiling the mystery of a 50-year-old short story, this happens in the The Borderland of Sol by Larry Niven.

JdeBP•5mo ago
If you enjoy that sort of thing, also read Killing Vector by Charles Sheffield.
pavel_lishin•5mo ago
I immediately thought of that story as I was reading the comment you replied to :P
BurningFrog•5mo ago
Flinging one at an enemy civilization could be a clean way to resolve conflicts!
Terr_•5mo ago
"Aside from permanently rending the very fabric of space and time itself, there was very little collateral damage."
waste_monk•5mo ago
Well, it's not like it's in short supply...
marcosdumay•5mo ago
It is practical? If you don't slow it down somehow it will pass through anything and go away through the other side.

Maybe you can time it to evaporate on your enemy, but that's an incredibly precise timing, and your enemy will literally be able to see it coming and deflect it.

prof-dr-ir•5mo ago
Cool. You would of course end up negatively charged yourself and therefore quite strongly attracted to the black hole.

So I would recommend moving your civilization to a Dyson sphere around the black hole before aiming your cluster of LHCs at it.

floxy•5mo ago
Don't forget color charge:

https://arxiv.org/abs/2310.16877

behnamoh•5mo ago
Yet another clickbait title by the quantamagazine. I'm afraid these "science popularization" techniques only make it more confusing for the general public. Just say the exact, scientific word and cut this bs.
renewiltord•5mo ago
No-hair theorem is just the name

https://en.m.wikipedia.org/wiki/No-hair_theorem

IAmBroom•5mo ago
Does the Hairy Ball theorem apply to hairless black holes?

Asking for a friend...

jleyank•5mo ago
If they finds "casual" names for scientific principles annoying, they're going to just LOVE the names for genes. hERG activity is a bad thing that gets drugs taken off the market (cardiac arrhythmia). hERG means "human ether-a-go-go-related gene". Scientists are human, and obviously playful at times.

It's not a recent thing. Check out quark names and their associated properties.

kgwgk•5mo ago
A few examples:

https://www.wikipedia.org/wiki/List_of_unusual_biological_na...

https://en.wikipedia.org/wiki/List_of_chemical_compounds_wit...

ordu•5mo ago
Yeah. The photo of a hairy astrophysicist claiming that if black holes have hair, it is shorter than 40 km seems like a petty way to spark a public interest.
mr_mitm•5mo ago
This is the first time I heard quanta magazine being accused of click bait. They show no ads and don't sell anything. What would be their motivation for using click bait?

Click bait used to mean things like "five reasons you always get sick - number three will SHOCK you" or "doctors hate this one weird trick!".

The title of this article isn't click bait at all. Black holes having hair or not is almost the technical expression, as evidenced by the "no hair" theorem. Physicists are quirky like that sometimes.

xeonmc•5mo ago

    The question of hairy black holes is intimately connected to the greatest puzzle in modern physics: How can general relativity be merged with quantum theory?
    
    Consider the situation where an object crosses a black hole’s point of no return, called the event horizon. According to general relativity, all outsiders will see is how the swallowed object contributes to the two numbers that describe the black hole: how much mass the object adds, and how much faster or slower it makes the black hole rotate.
The idea that anything within the event horizon should be treated as an opaque black box -- could it be reinterpreted as saying that any property which has dependence on spatial or temporal distribution within becomes an unknowable quantity? If so, can it be tied somehow to Quantum Mechanic’s idea of the removal of degrees of freedom by observation, since now certain quantities are not unobserved but rather unobservable in principle? I am asking this from a naive laymen’s point of view, so I may be conflating entirely unrelated ideas.
trjordan•5mo ago
Not exactly. Black holes are not lopsided, for instance. There isn't anything on "one side" of them, once the matter has crossed the event horizon.

Rotating black holes are pretty well modeled as a spinning ring: https://en.wikipedia.org/wiki/Ring_singularity

layer8•5mo ago
For one, observers inside the event horizon can still observe each other. From the point of view of an observer falling into a black hole, nothing unusual happens when they cross the event horizon. They still observe stuff falling in with them in the same way as before (assuming a large enough black hole so that the local curvature is negligible).

If Hawking radiation is real, it might also expose information from inside the black hole, possibly solving the information paradox. In that sense, the inside of a black hole would still be “observable” from the outside in the QM sense. But since we don’t know how quantum gravity works, that is an open question.

agent327•5mo ago
How can that be true? Inside the event horizon, there is only one direction: down. If light cannot escape, how can it happily bounce around, reflect on something, then reach your eyes? How could signals from your feet (say) even reach your brain, assuming a feet-first entry into the black hole?
layer8•5mo ago
When you cross the event horizon, you’re falling at close to the speed of light, relative to the event horizon. But due to relativity, light bouncing off the falling objects still propagates at light speed in all directions relative to the falling objects (including the falling observer). That light can’t move outwards, due to being inside the event horizon, and accelerates towards the singularity, but the observer accelerates to the singularity faster, relative to light being reflected outwards. The falling rest frame accelerates towards the singularity, but within that accelerating rest frame, light behaves normally between objects in that frame (assuming a large enough black hole so that the differences in radial distance between the objects is negligible).

Consider two cars driving on a highway at the same speed. If one of the cars decelerates, it appears to be moving backwards relative to the other car, while still continuing to move forward relative to the road. It’s similar for light and an observer falling towards the singularity. They both fall towards the singularity, but light being reflected backwards will fall a bit slower, thus appearing to move backwards relative to the observer, even though the light still moves forward toward the singularity.

thunderbong•5mo ago
Very well explained. Thank you
gus_massa•5mo ago
No. The "no hair theorem" has a condition that says "after a while", but people ignore it because it's a short time. So intermediately after the object entered the black hole will have bump and will emit gravitational waves and after a while it will be a perfect sphere (if it's not rotating, or a similar round elongated shape if rotating).

As far as I can understand, it totally unrelated to Quantum Mechanics.

griffzhowl•5mo ago
I think the short answer is that no one knows, because a proper answer would need an understanding of how black holes and quantum theory go together, which is not currently known.

The longer answer (if you want to get in to the extensive literature) is that your question seems to relate to the black hole information paradox https://en.wikipedia.org/wiki/Black_hole_information_paradox

Arwill•5mo ago
I think what is relevant here, is that there is a separation between the inside and the outside of the black hole. Since there is no communication between the two, on the inside it could be anything. And its not just the matter and space, even the laws of physics might be completely different. If it weren't so, then there had to be a "super-space" that communicates how ordinary space behaves on both the outside and the inside the black hole.
anuramat•5mo ago
with QM, the "unobservable" stuff is just guaranteed to not be there, eg a particle detected at (x,t) is definitely not at (x',t); so you are observing it "not existing there" -- collapse just makes the measurement at (x',t) redundant

meanwhile with black holes you know there is something, but you can't measure

in both cases you don't get any information, but in QM it's only because you already know everything there is to know about the system

could it end up being fundamentally the same thing? I don't see why not, but for it to make sense you'd have to get a nobel prize for grand unification theory first

also, collapse is not real and can't hurt you anyway, see many-worlds

datadrivenangel•5mo ago
Another blow against string theory.
importantstuff•5mo ago
You might want to consider the article more carefully, especially the section "Short Hair, Long Hair". The predictions of string theory are in no way falsified by the analysis conducted by these researchers.
IAmBroom•5mo ago
In fact, it's hard to find predictions of string theory that are falsifiable at all.
moralestapia•5mo ago
An interesting consequence of having "no hair" on them is that information on everything that falls in them is lost forever, which leads us to an information loss paradox. Not nice.
fpoling•5mo ago
You do not need a black hole for the information loss. Just shout a flashlight into empty space. Any information encoded in photons will be lost from the point of view of the sender.

And then the classical notions like information or entropy are not really compatible with General Relativity. Richard Tolman almost 100 years ago proposed interesting extension to the classical thermodynamics that is compatible and can potentially explain apparent paradox of information loss, but it is not known if that extension matches reality.

griffzhowl•5mo ago
> Any information encoded in photons will be lost from the point of view of the sender.

The crucial difference is "from the point of view of the sender". The black hole information paradox is that the information is lost from any possible receiver (even any possible ensemble of receivers surrounding the black hole). It's not the same thing

fpoling•5mo ago
The information is not lost from the point of view of receivers inside the black hole horizon.

Which again points out that the classical notion of information just does not work in a universe with multiple causally disconnected regions.

griffzhowl•5mo ago
What happens when the black hole evaporates then, and there is no more horizon? That's the black hole information paradox
butlike•5mo ago
Single point of ~infinite charge?
moralestapia•5mo ago
>The information is not lost from the point of view of receivers inside the black hole horizon.

Information is lost beyond the event horizon. There is no such thing as "point of view of receivers inside that black hole", everything collapses into a single point or some dimensionless thing or whatever. That's why it is called a singularity.

IAmBroom•5mo ago
I do not know of any theories that agree with this. In fact, most admit that "you wouldn't even notice (if somehow still alive) when you crossed the event horizon" - because the only thing that happens is the photons you emit go from taking billions of years to escape, to never escaping.

And that's not why it's called a singularity. It is NOT a single point, nor dimensionless. It has a well-defined dimensional size, the Schwarzwald Radius.

moralestapia•5mo ago
>I do not know of any theories that agree with this.

It shows.

You confuse "dimension" with "magnitude", for starters.

griffzhowl•5mo ago
> It shows.

Why be so extravagantly supercilious on the internet?

It's ironic because it seems you're not that familiar with general relativity, and confuse the entire region within the event horizon with the singularity.

Black holes have a causally connected region within the event horizon which is distinct from the singularity, so there can in fact be observers within the event horizon that are in communication with each other, and they can have a perspective, i.e. receive information. The simplest black hole model would be the Schwarzschild black hole (a static, spherically symmetric spacetime, which is empty apart from the central mass) with the Kruskal-Szekeres coordinates, which smoothly continue over the event horizon.

Here's a nice discussion by John Baez about what you might see as you cross the event horizon: https://johncarlosbaez.wordpress.com/2024/11/30/black-hole-p...

To some extent though, what really happens within the event horizon remains speculative, because we can't directly verify any of these predictions about what happens there without actually crossing the horizon ("What happens within the event horizon, stays within the event horizon"). We just make inferences based on the structure of our currently most predictive theory for gravitational phenomena outside event horizons (which is general relativity, ofc)

moralestapia•5mo ago
>and confuse the entire region within the event horizon with the singularity.

Can you point out where? I'm always open to learn.

Btw, I don't read Baez as I consider him trash.

griffzhowl•5mo ago
> Can you point out where?

Here:

> Information is lost beyond the event horizon. There is no such thing as "point of view of receivers inside that black hole", everything collapses into a single point or some dimensionless thing or whatever. That's why it is called a singularity.

I'd say you're missing out by not reading Baez. He's an extremely gifted thinker and communicator. He knows his stuff

alex1138•5mo ago
Black hole goes into a barbershop

Barber goes "You're kidding me, right?"

slipperydippery•5mo ago
Black hole goes into a barbershop.

Barber goes, "You're kiddiinnngggg mmmmmmeeeeeeeeee, riiiiiiiiiiiiiiiiiiiiiiiiiiiiiii...."

IAmBroom•5mo ago
The bartender says "We don't serve Tachyons here."

A Tachyon walks into a bar.

FergusArgyll•5mo ago
This reminds me of something I mull over; Greek style philosophy seems so smart, rational and correct until you actually observe the world. Imo the perfect example is elementary particles - the Greeks (mostly) were convinced that it's impossible for something physical to be elementary (cannot be further split) and logically it is hard to understand why can't we continue to split the particle?! but hey, we can't.

Physical beings which cannot be distinguished from one another would have made their heads spin...

JdeBP•5mo ago
Indeed. That's rotational frame dragging for you. (-:
wahern•5mo ago
Aren't quarks and, probably, electrons point-like particles? In that sense the fundamental subatomic particles aren't "physical" in the sense the Greeks would have thought of them, e.g. having a non-0 diameter, and in that way modern physics sort of vindicates their deductive reasoning. Their logic wasn't wrong, per se, it was their starting assumptions that were flawed (or at least incomplete), which is acceptable as far as deductive reasoning goes.
JdeBP•5mo ago
No. Because the GR/QM conflict comes up in the other direction that way. GR predicts infinities for zero-radius particles. Indeed, so too does classical electromagnetism. In any case, "quanta" does not really mean the same as the classical notion of point particles.

* https://youtube.com/watch?v=zPZrDbPAuKs

griffzhowl•5mo ago
To be fair to the Greeks, thay also came up with the idea of elementary particles. I think it's Democritus who's credited with the idea of "atoms".

It's been ages since I've read about him in any depth but I remember something about him having an idea that because of the indefinite divisibility of length then the elementary particles would have to have a diameter smaller than any given length, i.e. be infinitesimal, so they had quite sophisticated speculations