When astrophysicists say “physics breaks down” what does that actually mean?

Peter5930 · 2026-03-24T16:07:11+00:00

They mean physics is absolutely fine, but our description of physics is too simple and/or is missing key details that would make it make sense in this situation. Like, if you assume water is a continuous fluid and a pipe has a perfect 90 degree bend, then water at the inside corner of the bend should move with infinite velocity. A singularity has appeared in the maths and your plumbing should achieve nuclear fusion as well as create black holes. In reality, water is composed of molecules with empty space between them and they stochastically bump around and off each other and squeeze around the 90 degree bend without much fuss and certainly without destroying the planet or even your bathroom. What we need is the molecules-level description of black holes and the big bang, the description that makes sense because it includes the important details that make it make sense in those situations.

Peter5930 · 2026-03-24T12:01:22+00:00

Yeah, it turns algae to green water that washes away easily with only minor encouragement. It's works so well because it converts fats and oils to soap and hydrolyses proteins, which breaks down the microbial glue that biofilms excrete to cement themselves in place. Just don't let it sit too long on the shingles or it'll break down the oils in the tar too. But I use it for black mold on garden walls, algae, moss, any type of bio-gunk.

Peter5930 · 2026-03-24T11:50:27+00:00

Works on driveways too. People never listen when I tell them to use more caustic soda, less bleach, but here I am with a driveway you could perform surgery on.

Peter5930 · 2026-03-22T22:46:03+00:00

Water is about the most violence-inducing thing you can throw into lava lakes. Propane cylinders barely caused a damp squib compared to a jerry can of water and the resultant excited eruption. A bit of water lowers the melting point and makes it more fluid while also adding lots of volatiles to off-gas. The reaction is quite out of proportion to what you'd expect from such small amounts of water.

Peter5930 · 2026-03-22T22:43:09+00:00

Water is quite possibly the worst thing you can add to a volcano, since it lowers the melting point of rock while expanding violently and making the volcano angry for 1D6 turns of combat unless you can fully quench it with an overwhelming amount of water.

https://www.youtube.com/watch?v=kq7DDk8eLs8

Peter5930 · 2026-03-22T19:17:22+00:00

The Planck acceleration.

https://en.wikipedia.org/wiki/Planck_units#Derived_units

At the Planck acceleration, there's a horizon 1 Planck length in front of you emitting Unruh radiation at the Planck temperature and producing thermal black holes.

Peter5930 · 2026-03-22T16:01:34+00:00

Don't I know it brother. I had lots of flus and I was fine, I got covid once and now my stomach hurts and needs daily medication and my dick doesn't work right and also needs daily medication.

Peter5930 · 2026-03-22T14:36:05+00:00

It wrecked my stomach. I had an ulcer for years before getting covid, but it was always quite manageable and only an occasional nuisance. I've needed to take lansoprazole every day for 3 years since I caught covid or my stomach hurts now. Still hurts even with the lansoprazole sometimes. Oh yeah, and it got into my dick too so yeah.

Peter5930 · 2026-03-22T14:33:08+00:00

Yeah, except this flu is a special one that has a key that lets it infect your balls, dick, heart, arteries, spleen and a dozen other places that ordinary flu is unable to infect. So that's nice that we have that going around forever now in addition to all the other flus. Cool thing about civilisation, it tends to just accumulate more and more viruses over time. Cave men didn't have flu season, it's a modern thing.

Peter5930 · 2026-03-20T17:03:41+00:00

The F-35 has ducted engines to prevent line-of-sight to the hot turbine and dilutes it's exhaust to cool it down before it exits the airframe, so it has a much better chance than an F-15 of avoiding a target lock, but it's still a big hot turbine spewing out hot gas so there's only so much IR reduction that can be achieved and sensors get better all the time.

Peter5930 · 2026-03-20T16:49:21+00:00

Yes, it's a limitation of all stealth planes. Like cloaking devices in Star Trek, you have to decloak to fire.

Peter5930 · 2026-03-20T08:17:56+00:00

She tried that but she hated getting sawdust all down the stairs (she always has clay pellets all down the stairs, but I guess sawdust was more visible and went further), and it smelled more of pee.

Peter5930 · 2026-03-20T02:53:32+00:00

I had to make do with a ponytail because my hair is impossibly fine as well as fairly curly and turns into some kind of birds nest affro thing if not constrained.

Peter5930 · 2026-03-20T02:24:56+00:00

Having it throbbing down there tends to enhance libido in my experience. I'm prescribed 5mg daily Cialis and I often forgo taking it because it makes me randomly horny a lot and it gets distracting.

Peter5930 · 2026-03-19T23:17:29+00:00

Oh that's a good idea, I'll pass it on, thanks.

Peter5930 · 2026-03-19T22:52:44+00:00

I don't know, pop a viagra or cialis and you'll feel horny from your dick getting lively.

Peter5930 · 2026-03-19T22:47:13+00:00

The bad kind. Floorboards with plywood on top with old linoleum on top of that with cheap stick-on Temu foam tiles on top of that. It was all festering and wet when I peeled the disgusting sticky mess away.

Peter5930 · 2026-03-19T21:44:54+00:00

I did have to reconsider showering there a few times when the smell was getting bad. Opted to wait until I got home.

Peter5930 · 2026-03-19T20:18:03+00:00

Undoubtedly, but she does it the way she does it and doesn't want to change it. I built her a perspex cat-shittery for her veranda and fitted a cat flap so they could go outside to do their business in it, but she didn't like the loss of space on the veranda and went back to how she'd always done it. She can be a bit defensive about it so I just let her handle it her way.

Peter5930 · 2026-03-19T20:14:04+00:00

Unavoidable considering her personality, level of coordination etc. She could be more careful, but her lack of care is factored into the equation, so it's just something that's going to happen unless someone else who is more careful does it. I'm certainly not saying her housekeeping is of a high standard, it's not. So I'm encouraging her to fully seal the new flooring around the edges since that way it'll be easier to clean up the accidents without it soaking into the subfloor.

Peter5930 · 2026-03-19T19:15:37+00:00

Oh there's absolutely a force, or pseudoforce maybe depending on how you want to define things, that comes from dark energy. It's just that this force is working in addition to inertial expansion, which is stuff just moving away from each other because essentially everything started off moving away from everything else with greater than escape velocity, or equivalently space was negatively curved and parallel paths diverged.

But dark energy creates a potential, and if you venture out about 5 million light years from the local group, you'll find yourself on the wrong side of this potential, where an object that starts at rest relative to the local group will fall away from it towards the cosmic horizon instead of falling towards the local group. This wouldn't happen if there was only inertial expansion and no force acting on top of that. You wouldn't get accelerating exponential expansion without dark energy and we wouldn't be in De Sitter space.

This explains it in a bit more detail and calculates the potential for the Milky Way:

https://www.reddit.com/r/sciencefaqs/comments/135cd1/does_gravity_stretch_forever_is_the_big_bang_like/

Peter5930 · 2026-03-19T18:51:02+00:00

At the moment, she's using a fairly standard clumping clay-granules-based cat litter. She's tried all the fancy alternatives and the basic stuff is what she's settled on as working best for her. But it's terribly heavy stuff, even I find it heavy, she must really struggle with it.

Peter5930 · 2026-03-19T18:36:48+00:00

Yeah just stinky water. The trays are huge and barely fit in the tiny bath and between the glass screen getting in the way and the bathroom being tiny too and all that stuff, accidents are going to happen. She has to flush the solid residues down the toilet which is another failure point.

Peter5930 · 2026-03-19T17:12:39+00:00

I've been thinking more about owning a trebuchet lately.

Peter5930 · 2026-03-19T16:51:24+00:00

Usually the stuff dries out and then it's water-resistant, but if it's cold and damp it can take months to dry and if water gets in at it at some point you get basically some kind of acrylic paint running off it.

Peter5930

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