MalbertKerman

That only holds in the near field of the reflecting surface, which is roughly (it's a fuzzy boundary so who cares about a 2 pi here or there) where the ratio of distance to width of the surface is less than the ratio of the width of the surface to the wavelength. For wavelengths around 10^-2 m and surfaces around 10^0 m, that means distances within 10^2 m. Much further than that and the reflected wave is spreading out and falling off as 1/r^2. A radar working at ranges of tens or hundreds of kilometers is firmly in the far field.

There's still a strong angular dependence in the reflection amplitude; 1/r^2 fall-off does not imply isotropic distribution.

Why does detection scale as the 4th root of the RCS?

Because the power returned to the antenna scales as the -4th power of the distance to the target, and detection depends on that power being greater than some threshold. If the fourth power (rather than the square) is surprising, think of the reflection as re-transmitting the power that arrived at the target. The incident power on the target goes as RCS/r^2, and the power that makes it back to the original antenna gets another factor of 1/r^2, so the return scales as RCS/r^4.

To me, all-lowercase text comes across one of two ways:

(a) I felt speed was far more important than readability (reasonable for rapid-fire short messages or constrained typing ability such as a flip phone, also a common way to imply "fuck you, my time is more important than yours" in longer forms such as email), or

(b) i'm 14 and e e cummings is so deep (blogs)

I don't know whether to feel proudly clever or frighteningly jaded at having spotted this one by "industry standards." Nice.

then wouldn't that require a razor's edge of criticality?

Yup. From the device description in its decommissioning plan:

  The CFX was a sub-critical assembly of uranium-2-35 surrounding a Cf-252 source. The function of the U-235 fuel was to multiply the neutrons coming from the Cf-252 source, which fissions spontaneously. The CFX was designed never to exceed a Keff of 0.99. The CFX assembly yielded sufficient neutron fluxes for applications such as neutron activation analysis.

And quality educational content like "Hokay, so, here's the Earth, chilling. 'Wow, that's a sweet Earth,' you might say. ROUND!"

The hard part isn't having a telescope, but analyzing the images for objects that have moved between successive observations. Digital astrophotography and analysis software have been getting steadily cheaper and better, which leads to more amateur comet hunters each watching more sky, which has rapidly improved the odds of catching rare objects.

I'm not sure how the progress of institutional and amateur observations compare. Obviously the big guys benefit from the same technological advancement, but I don't know whether the fraction of new objects discovered by amateurs has been growing or not. I suspect the odds of the first interstellar object being found by an amateur were still pretty long.

100 days with zero emissions

By my back of the envelope math, burning 600000 kcal should produce couple hundred kg of CO2. You could also make that crossing in less than a third of the time under sail, with about a third of the daily calorie consumption, for maybe a tenth of the CO2 output.

MCUs particularly from microchip had really good documentation

Oh how the mighty have fallen. I've only worked on one major project with a Microchip MCU (PIC32MK), but their documentation and support were terrible. No detailed documentation, just a driver library with vague, sketchy API docs and disgustingly bug-ridden code. Deadlocking race conditions in the CAN driver, overflow-unsafe comparisons in timers, just intern-level dumbassery that you couldn't fix without reverse engineering the undocumented hardware. Oh, and of course what documentation did exist was split into dozens of separate PDFs, individually served, many of which were 404 unless you went hunting for older versions or other chips in the product line. It certainly cured me of any desire to touch another Microchip product.

How fitting that it ends with September, whether that's September 30th, 2025 or September 11718th, 1993.

No (Betteridge, 2009).

I did get a lot of that in the lower level math courses, where it kinda felt like the math faculty were grudgingly letting in the unwashed masses to learn some primitive skills to apply [spit] to their various fields, and didn't really give a shit if anybody understood anything as long as the morons could repeat some rituals for moving x around on the page. I didn't really understand integrals until the intermediate classical mechanics prof took an hour or two to explain what the hell we had been doing for three semesters of calculus.

But when I did go past the required courses and into math for math majors, things got a lot better. I just didn't find that out until I was about to graduate.

and I was annoyed that nobody had just told me that because I would have gotten it instantly.

Right?! In my path through the physics curriculum, this whole area was presented in one of two ways. It went straight from "You don't need to worry about the details of this yet, so we'll just present a few conclusions that you will take on faith for now" to "You've already deeply and thoroughly learned the details of this, so we trust that you can trivially extend it to new problems." More time in the math department would have been awfully useful, but somehow that was never suggested by the prerequisites or advisors.

It's quietly reversing the traditional "We approximate the cow to be a sphere" and showing how the spherical math can, in fact, be generalized to solutions on the cow.

The jump from spherical harmonics to eigenfunctions on a general mesh, and the specific example mesh chosen, might be the finest mathematical joke I've seen this decade.

The hard part is not realizing that one should stop caring. It's learning how to stop caring. For most of us, caring is an automatic, reflexive response, and changing it is not a trivial matter.

On my personal 2017-vintage i5-7200U, GIMP opens in under 5 seconds. On the computer I had for my last job, a 2023-ish i7, about 30 seconds. The problem was the shitheap of corporate security software that bogged down the zillion file access operations during application startup, not the app itself.

To be fair, the quality of software has dramatically dropped, apps now take 10 seconds to load, memory usage is maxed, games crash and people needed to reinstall their OS so frequently that Microsoft literally added a "reset PC" option..

Are you talking about the 90s or now? Because those were all at least as true then as now. Everything took forever. You needed more RAM every month. Everything crashed constantly. I had to reinstall Win98SE so many fucking times that I can still type F73WT-WHD3J-CD4VR-2GWKD-T38YD from memory.

The amount of suck in commercial software is constant. Companies always prioritize adding the shiny-looking features that sell software to rubes over improving things like memory use, response time, and general quality of life until the quality of life is actually bad enough to drive customers to another vendor, so it's perpetually bad enough to keep the average customer right on the edge of "oh fuck this, I'm switching to something else."

Somebody just discovered E. E. Cummings and thought "I'm gonna be original just like that guy!"

Combustion cycles that run the turbopump exhaust into the main combustion chamber are called "staged combustion." The Soviets had staged combustion engines putting payloads in orbit in 1960, and the US flew its first in 1981.

SpaceX's advance was going from oxygen rich (where all of the oxidizer and a fraction of the fuel run through the preburner and turbine, as used in the Soviet/Russian engines) or fuel rich (vice versa, used in the Space Shuttle) to full flow (which has both oxygen- and fuel-rich preburners and all of the propellants flow through one turbine or the other).

The rocket folks call them "turbopumps" rather than "turbochargers," and most of them are powered by a separate combustion apparatus (with non-obvious terminology: if, after going through the turbine, the gas will then end up in the main combustion chamber then it's called a preburner, but if the gas will be discharged outside the main combustion chamber then it's called a gas generator).

There is one type that comes closer to a turbocharger's operation: the "tap-off cycle" runs the turbine on gas drawn from the main combustion chamber rather than using a separate combustor. Tap-off cycle engines aren't common but Blue Origin and Firefly are using them.

There are 25 unique responses in that 1000-line file.

And aligned to a properly synchronized cardinal grammeter.

Ye olde Rutherford experiment nicely illustrates the points of 'yes it is all empty space'

No, it does not. It illustrates that the portion of an atom that strongly scatters alpha particles occupies a small fraction of the atom's volume. Asserting that alpha particle scattering is the only correct definition of the threshold between emptiness and non-emptiness is an awfully strange position to take.

When interacting with other electrons at energy scales relevant to human life, i.e. maybe ten electron volts and down, an electron cloud is somewhere between solid (core electrons especially in heavy atoms) and squishy (valence electrons). Give a rock the ol' "I refute it thus!" and your toes will report that that rock's electrons are quite competently occupying their space.

Ask an alpha particle at nuclear energy scales a million times greater, and that electron cloud is like a swarm of gnats to a speeding car. The electrons only interact with the alpha electromagnetically, and it takes another object that interacts through the strong nuclear force to really bother a nucleus (most of the time).

Ask a neutrino, and it will tell you that all the nuclei in the Sun are but a wisp of fog.

This is a good example of how approximations valid in one regime fail in another but are not therefore useless. Rutherford's experiment reveals that there is more going on with matter than what can be probed by fingers and microscopes and chemical reactions, but it in no way invalidates those other observations.

To be fair, what he proposed isn't (immediately obviously) mutually exclusive with your points. If it were true it would be almost impossible to detect experimentally.

The obviousness or lack thereof is subjective, but the exclusivity is firmly established. The absolute indistinguishability of particles is deeply woven into quantum mechanics; you don't get a Pauli exclusion principle without it, for example. If the particles remembered their previous lives, and an electron that used to be tied to an iron nucleus weren't completely identical to one that used to be stuck to a carbon nucleus, all of quantum mechanics as we know it would be impossible.

I don't know if it's generational or a matter of background. For me, as the sort of person who knows exactly where to find the SCE power switch, it would be impossible to conceive of this font as ugly. So much ingenuity has been expressed, so much craftsmanship given material form, so many feats of industry and exploration and mundane utility accomplished through those shapes that I find them definitively beautiful.

If some community teaches Rules of Beauty which these characters contravene and are thereby deemed ugly, that says more about the merit of such Rules than anything else.

That ampersand, though... okay. You can have that one.

It's only true for a single junction. https://en.wikipedia.org/wiki/Shockley%E2%80%93Queisser_limi...

Multi-junction cells beat that limit, but they're still horribly expensive to manufacture which confines them to niche uses like spacecraft.

Refrain from making decisions until all possible stakeholders can weigh in

Create overly-ambitious timelines and set impossible-to-keep deadlines

Send unnecessary meeting invites then cancel them last-minute

Don't use collaborative software, just email things back and forth

Introduce burdensome software license approval processes

Leave off the phone or video call information from a calendar invite

Forget government, this is a summary of standard operating procedure at my last (large, private sector) employer. Maybe they weren't all idiots, they were just fighting the man.

Just like the original Simple Sabotage Manual, this is worth reading just to reflect a painfully clear image of your own organization's dysfunction (and possibly your own role in it).

"Bent pipe" dumb repeaters are still common for geostationary satellites, AFAIK. Being future-proof against anything except spectrum reallocation (modulation and protocol upgrades can be implemented just by changing equipment on the ground) is valuable for things with long lifespans and high replacement costs.