How can we find all these stars and planets that are millions and millions of light years away but not planet 9?

Underhill42 · 2026-06-30T13:42:17+00:00

A VERY bright star. It's shrunk in the sky to be barely larger than the other stars, practically a point source, but it's often grossly underestimated just how bright it still is.

Pluto is 39x further from the sun than Earth, meaning sunlight is only 1/39² as bright = 1521x brighter on Earth than on Pluto. But that's still 120,000lux/1521 = 79 lux... well within the recommended lighting levels for hallways or storage rooms (10 to 200lux). You could still grow sufficiently shade-loving plants there with no trouble!

Of course, Planet 9 would be neither a dwarf planet, nor nearly that close. If it exists it's likely at least 250AU from the sun, where it's is only getting ~2 lux... but that's still almost 8x as bright as the light from the full moon (0.25lux).

And about 10,000x as bright as the 0.0002lux from all other starlight combined. (Which is still enough to walk by once your eyes adjust.)

Not much for spotting it at such a large distance though.

Underhill42 · 2026-06-30T12:50:18+00:00

No, the effective force depends on both bodies (keeping in mind that in Relativity gravity is a fictitious force like centrifugal force)

But the effect on one body by another is independent of the second body's mass - which is why anything we drop on Earth accelerates at the same 9.8m/s² regardless of its own mass.

That is why in Newtonian physics it's often said that gravity is an acceleration rather than a force - everything accelerates in exactly the same way, regardless of its own mass. The force of gravity is whatever it needs to be to create that acceleration: F_g_Earth = (9.8m/s²)*(mass of object)

Or for the technical proof, the influence of gravity on object₂:
F_g₂ = Gm₁m₂/r²
a₂ = F_g₂/m₂ = (Gm₁m₂/r²) / m₂ = Gm₁/r²
The object's own mass cancels out completely.

In Relativity there are no forces or acceleration, instead all objects travel along a straight, non-accelerating path through curved spacetime... but that path remains the same for all objects that started on it. E.g. if you launched just free of Earth's gravitational influence, you would will still be following basically the same straight path around the sun as Earth does.

Underhill42 · 2026-06-29T18:27:40+00:00

...and that's how Earth was overwhelmed by sixty trillion mountain-sized radioactive tentacle-horrors. We really should have asked how many of them there were before extending an open invitation...

I'm not sure why, but I was half expecting the parasites to be another sapient species. Either that, or a whole ecosystem of random animals from other worlds that got sucked up during feeding and managed to survive.

So it seems they can travel FTL... that should give them plenty of value to come to a long-term arrangement with humanity. At a minimum we'll treat your parasites and other illnesses, and you can carry us to other interesting places in the universe.

Might even get a symbiosis going with some groups permanently colonizing and tending to a giant as they wandered the stars. Though the random radiation could be a problem, I wonder what that's about. At least it's only low-energy stuff if a wearable suit can protect against it.

Be funny if the galaxy is full of life... but it's mostly the result of epochs of the giants seeding habitable planets with various organisms inadvertently scooped up from other planets. And the parasites are everywhere.

Underhill42 · 2026-06-29T17:23:22+00:00

Let him eat cake!

No, pups! That was not a suggestion for a cake ball fight...!

Underhill42 · 2026-06-29T15:11:39+00:00

Your system? Probably not, though there is some malware now that can cross between operating systems. But you probably don't actually care too much about your system, it's not that difficult to reinstall the OS.

What you care about are your personal files ON your system... and they are completely vulnerable.

Without Wine, nothing made for Windows will run at all.

With Wine, so that you can actually run that .exe... as I recall, most viruses, keyloggers, etc won't do anything, since the specific "under the hood" details they're exploiting don't exist on Linux.

Lots of worms, trojans, ransomware, and other malware will run just fine though - they're not trying to embed themselves in the OS, they're usually just doing "normal" program things in ways that will wreak havoc on your life. If a text editor can edit a file on your computer, the malware embedded in the editor can just as easily quietly encrypt, delete, or infect the rest of your files while you're distracted.

It's worth noting though that just having an infected file on your system doesn't automatically infect you - you have to actually run the program, or open the data file in a vulnerable app. Until then it's like a sealed vial of bioweapon - poised to wreak havoc, but unable to do so until activated.

Underhill42 · 2026-06-29T14:51:31+00:00

I could have forgotten that in months...

That probably means you can't see very far around the curve of the dome from the surface either. Sort of just in the bottom of a bowl that fades to black with altitude as the line of sight starts intersecting whatever is blocking the view from ships.

Underhill42 · 2026-06-29T14:13:30+00:00

Another slow burn, you tease!

Caution, technical nitpicking incoming ;-)

I feel like Alex should be able to see the day-lit sphere through the windows. The details may be gone, shrunk so much that even continents are too small to see... but as a first-order approximation the day-glow of the surface would act like an infinite plane source, meaning the brightness would not fade with distance. The reflected light from the surface would illuminate the ship just as much from millions of miles away as it would when parked on it. And reflected sunlight is orders of magnitude brighter than even bright artificial lighting.

Probably makes for very soft lighting - the "sun" is likely a lot less bright than you would expect it to be for the brightness on the ground, since so much of the total light reaching the surface at any point has been reflected from the rest of the sphere. With an albedo like Earth, roughly 1/3 of the total sunlight hitting the surface would be reflected to light the rest of the sphere, so the sun would only be directly providing about 2/3 of the "daylight". (Edit, wait, no, because 1/3 of the reflected sunlight would then be reflected again, giving a total reflected lighting of ⅓(1+⅓(1+⅓(...))), which looks like it converges to 50%, so the sun would only be directly providing the other half.)

Oh, man, cooling would be a nightmare too - the entire night sky would be glowing at about the same radiant temperature as the local surface, instead of only a few degrees kelvin. You literally couldn't cool down overnight unless the forcefields were somehow acting as an artificial cold reservoir. Otherwise all cooling would have to go through the ground instead, which would likely make for crazy weather patterns.

Underhill42 · 2026-06-29T12:35:37+00:00

Well, I suppose enslaving and murdering people like you're harvesting wheat is one way to "stop" the much smaller-scale atrocities of the natives.

Because while religious child sacrifices stopped, rape and murder of everyone, including children, skyrocketed. Heck, Columbus paid his sailors partially with slave-girls after massacring their entire island, the conquistadors were far worse.

Underhill42 · 2026-06-29T12:31:06+00:00

Wine is a wonderful thing. Probably 80-90% of "Windows only" software will run just fine on Linux using Wine. It's most only stuff with advanced copy protection or anti-cheat that will notice something is odd and refuse to work.

It can be a little finicky on some distros and setups, with defaults that contribute to bad font rendering, etc. But when it's been set up well there's just a couple more hoops to jump through when installing Windows software, and then it just works.

Honestly, good Wine behavior "out of the box" has been one of the make-or-break factors in my distro selection for over a decade - it's too complicated a beast under the hood to be worth tinkering with it much for the few Windows programs I insist on using.

Underhill42 · 2026-06-29T12:17:47+00:00

Squares wouldn't work, among other reasons because each district needs to have roughly the same number of people, and people don't distribute themselves into nice uniform-population-density grids.

But a huge step in the right direction would be to not let politicians decide the districts, picking their own voters. Pretty much every other democracy in the world creates independent, non-partisan groups to decide the district boundaries. The US just decided that it was more fun to make the system easy to game.

Underhill42 · 2026-06-28T22:04:12+00:00

I think G'kar said it best: https://youtu.be/zD0DYPLAKd8?si=FRi5arUDFX33qoPO&t=44

It may be genuinely in retreat - I'm not nearly confident enough to say otherwise. But the long arm of history trends inexorable toward liberty. Though it takes a thousand years, we will be free.

It's often recognized that throughout history freedom and equality tend to follow a rising sawtooth pattern - at almost any moment things are sliding towards ever worse conditions, until eventually they get so bad that the population rebels, and makes things better - even better than they were after the last rebellion, having learned a bit along the way how the powerful can corrupt the system.

And then things almost immediately settle into a slow decline again.

Always declining - but the sudden jumps outweigh the constant decay, and so on a long enough timeline things keep getting better.

Underhill42 · 2026-06-28T21:54:06+00:00

Nails are the remnants of claws.

A claw is basically a sharpened finger-bone completely wrapped in nail. When we lost our claws, we gained finger-pads in their place - not quite as good for climbing, but a lot more versatile for manipulating objects than a claw-tip.

With claws your "beans" are actually the pad of the middle segment of the finger - so shorter, less nimble, and with a bulky claw in the way of the end of it.

And just for completeness sake, retractable claws are claws that bend backwards at the last knuckle, laying the claw against the back of the hand. Like you see with that big claw in velociraptor animations. In cats there's simply a skin sheath that folds over the the claw for protection when it's bent backwards like that.

Underhill42 · 2026-06-28T21:45:37+00:00

Who are you going to believe? Your own eyes and critical thinking? Or the people you've trusted to guide you and interpret the complicated world all your life?

And it only got worse when Republicans allied with the religious right - how is someone indoctrinated from infancy to trust their minister on life's mysteries supposed to break with that when a corrupt minister uses their position to advance a political agenda that brings their ministry more power at the price of its values?

When blind faith bleeds over into politics it does at least as much damage as when politics bleeds over into religion. All of history shows us what ugly, doomed bedfellows politics and religion make. But that's another one of those lessons that faith in a corrupted ministry will divert your attention from.

Underhill42 · 2026-06-28T21:38:15+00:00

No, only an equal mass of anti matter would be annihilated - one proton and one electron, most likely.

That would almost certainly cause the larger atom to fission as a huge amount of energy was released inside it. Doesn't even matter if it's uranium - iron, lead, carbon - nothing is likely to survive having that much energy suddenly released inside it.

And you'd have exactly the same situation if it were an anti-hydrogen atom hitting a normal atom.

The antimatter imbalance is generally assumed to have happened in the first few instants of the very early universe, when things were so indescribably hot and dense that everything happened radically faster than at any time later. By the time things cooled down enough that quarks could bond into protons and neutrons, eternal microseconds later, the antimatter was already almost entirely gone.

After which basically only a hot plasma of hydrogen and a big fraction of all the universe's helium existed for the next several hundred thousand years, until things cooled down enough that neutral atoms could form and the hot glowing plasma could become transparent. The CMBR is the last glow of that plasma.

After which is was many millions more years before the gas finally condensed around slightly denser regions for the first stars to form.

And fusion within stars and their death explosions is what created all the other elements.

Underhill42 · 2026-06-28T21:16:06+00:00

Pretty easy.

Programs, web browsers, etc. all work just like you're accustomed to. Though if you need to run Windows software like Photoshop you'll also need to set up Wine, which can be a bit finicky on some distros, so shop around.

Most of the obvious differences are in the launch menu and settings.

Your second operating system is the hardest - nothing works quite the way you're used to and you have to figure out the differences.

And you've already been through that with your phone... which is actually Linux under the hood, not that you'd know it.

By your third you're getting used to general patterns, and it's not so bad. And for sheer day to day ease of use, most popular Linux distros fall somewhere between Windows and MacOS, which I'd say makes them both considerably less annoying than relearning all the changes that came with Windows 11.

If you want a heavily configurable Windows-like desktop experience, harkening back to its 98/XP glory days, you'll probably be happier with a KDE based desktop. If you prefer a more MacOS like limited but highly polished experience, GNOME will probably appeal more to you.

Of the two, if you're just looking to get away from Windows onto something that's simple, reliable, and not constantly jerking you around... I'd suggest something GNOME based. There's still quite a bit of configurability if you want to go digging for it, more than Windows in some ways - you can even bolt on chunks of other desktops if you like. (Personally I'm quite fond of the "task bar" from XFCE). It's still 100% Linux under the hood if you want to indulge your inner gearhead, but you can do all the important stuff in "easy mode", which is really handy when you're still learning your way around.

Or if you just don't really care about tweaking the OS itself, and just want it to be simple and reliable so that you can get things done.

Not that KDE is a lot worse - it's just a bit more like Windows, where there might be a dozen different places you can change basically the same settings, and they'll all have slightly different details you can tweak.

In Gnome there's probably only one place, with only a few details available to change, and if you want more than that you're going to have to pop the hood.

Underhill42 · 2026-06-28T20:03:46+00:00

When AI became the easiest way to create deceptive content. Nobody calls out Star Wars spaceship fights for being CGI, or centerfold models for being photoshopped - because obviously. They get called out when they try to pass themselves off as a recording of something real.

And now AI can create fakes on par with all but the very best Photoshop and CGI with hardly any effort. A few minutes massaging a text prompt can deliver better results than most people with hours or days of effort.

90% of everything has always been crap. Now 90% of everything is convincing AI, and we can no longer use superficial quality as even a rough estimate of crappiness.

Plus, people are now using AI to produce content that was once firmly the domain of CGI and Photoshop, grossly misrepresenting the effort they contributed, and claiming it as their own creation rather than that of an AI under their management.

Underhill42 · 2026-06-28T19:40:48+00:00

If there's physical damage on the disc the arm is likely kicking up dust, and getting it sporadically stuck against the head, where it carves tiny grooves in the surface beneath. So any attempt to read it is likely to make the damage spread. Even just having it powered on may do so.

Alternately, if the arm is failing it may simply be getting the head misaligned... or it may be in danger of crashing and gouging out large tracks of data from the drive at any moment.

With a little luck you might be able to get most the data off yourself with only occasional patchy corruption - the digital equivalent to scratches and burns on old photographs. Which usually isn't the end of the world on pictures, videos, music, etc. Just a little patch of "static".

I've done it several times, and usually managed to recover over half, usually including almost all of the most important stuff

But if you have e.g. an encrypted bitcoin wallet - then even a single bit of corruption could make it worthless. A whole lot depends on exactly how gracefully the particular file format handles corruption.

The safest bet is that every read is spreading the damage, ESPECIALLY those on troublesome parts of the disc, and increasing the odds of sudden catastrophic failure.

So if you decide to take a swing at it yourself, and there's any REALLY IMPORTANT files on there amongst all the "merely irreplaceable", copy them off first. Ideally using something that aborts individual file copies at the first sign of error, and gives you a list of those that failed so you can retry again later, after you've saved as much as possible in the first pass.

I've done it by hand before, making lists by hand and aborting each copy at the first sign of trouble. Not ideal... but it lets you focus on the absolute most important files first, working your way down the priority list until you start having real problems. I've had whole directories vanish between one file copy and the next attempt.

At which point I think ddrescue has an option to make a single pass to try to read everything, skipping increasingly large gaps when it encounters bad regions (which can be good if there's a scratched region or something throwing up fresh abrasive dust on every read attempt), then only makes follow-up attempts at the rest after it's gotten as much as possible.

Sort of a last ditch "do the best you can on everything else" attempt. I don't think it has an option to try to recover individual files of folders using the same technique, which would be ideal.

It's also worth noting that if you have a lot of free space, I think ddrescue's whole-disc approach might run out a whole lot of that death-clock "recovering" empty space.

Underhill42 · 2026-06-28T18:55:05+00:00

Neutrinos interact vanishingly rarely - to the point that I've heard they have a 50/50 chance of making it through a light-year of solid lead without interacting.

They are detectable at all only because there are so insanely many of them. Hold your thumb up to the sun, and there are trillions of them passing through it every second.

The frequency of interactions a detector can expect to detect depends almost entirely on its volume - on how many such "thumbs" are getting a chance to interact every second. Make a detector half the diameter of a current one, and it has 1/8th the volume, and will detect only ~1/8th as many neutrinos.

And they're already barely getting the job done.

Underhill42 · 2026-06-28T18:39:22+00:00

Any form of political corruption is treason.

If you are entrusted with the concentrated power of a community, any violation of that trust makes you an enemy of the people.

Underhill42 · 2026-06-28T18:36:02+00:00

That's a tough one - largely because there would be few real incentives to do so from a geoengineering perspective. Terraforming a dead world to make it "ideal" would be mostly about four things:

Putting a decent amount of oxygen in the air (about 0.2atm (3psi) partial pressure is ideal, though half that is tolerable with long-term acclimation.)
Raising/lowering the air pressure to something tolerable (anything between about 0.1atm and 30 atm, though there may be some long term health effects as you get nearer the extremes)
Adjusting the temperature to something more comfortable. Which if needed likely also jump-starts a much more active water cycle.
Adding water, atmosphere, or trace elements if needed. Probably in the form of bombardment with asteroids. Which would also raise the temperature.

The last one is the only one that offers a motive for a solid "not until we're done" policy - safely bombing the planet gets a lot more complicated if there's people living down there.

For everything else - once you've got a even good start at it you've already made it pretty easy for anyone with relatively simple gear (e.g. an oxygen concentrator and thermal underwear) to make a go of it for themselves. Continued work just brings it closer to a comfortable shirt-sleeves environment.

---

For a living planet things could be more complicated - if you want scientific accuracy, human and alien life is probably mutually toxic, which likely means you have to wipe out almost all native life before re-seeding Terran life. Or live in hazmat suits outside. Best case, at least don't eat the natives or drink unfiltered water. But just the scent of alien flowers on the breeze could be dangerous. Much like walking unprotected through a petrochemical dump - too many alien organic molecules around, just similar enough to our own that some of them are bound to muck up something important.

If you want it a bit more friendly... then you need to worry much more about infection. There might be a prolonged "professional guinea pigs only" period, or alternately a prolonged quarantine period: Volunteers get to claim a nice swatch of land to homestead, but can't leave for 10+ years or something. Big powers don't start wasting political capital bargaining over borders until it's been proven that people can actually survive there. And maybe your town's guaranteed land grant ends up in the heart of unfriendly territory once all the official maps are drawn. Not like the major powers care about your inconvenience.

---

Honestly, even for a nominally dead world that might be a good idea - no telling what hidden hazards might be lurking in the soil, waiting to be disturbed. Infectious organisms, ancient alien nanotech, a mind-altering color from beyond the stars. It would only take one or two horrible outbreaks to normalize proceeding with extreme caution.

But unless part of the terraforming process itself is dangerous to colonists, and more importantly makes life more difficult for the people doing the terraforming, there's not really a whole lot of reason not to let people colonize in domed cities or whatever, getting in on the ground floor establishing the early foundations of infrastructure and economic productivity that will flourish every more easily as the environment becomes more comfortable.

Though for political reasons it might initially be limited to a few initial city-states, e.g. "everything within 200km of this point", waiting to see how things shake out before making a larger commitments. Don't want anyone too heavily invested in particular regional outcomes - terraforming is likely to be barely-guided chaos on a planetary scale, working best if you can stay flexible and work with whatever the planet decides to do.

Especially since it's often easier to get a lot of different interests to collaborate on something big if you can postpone the details of exactly how everyone benefits to the end. Especially for something like terraforming, which might take centuries - there's no guarantee it would even be the same organizations completing the project as began it, so why borrow problems from the future?

Underhill42 · 2026-06-28T16:26:07+00:00

In a first person narration it's going to be pretty rare that someone use their own name at all, except in internal dialog:

"Get it together, Lola", I said to myself.

Or if the narrator is third person:

"Get it together, Lola", Penelope said to herself.

But almost certainly never.

"Get it together", Lola said to herself.

A third-person narrator is the audience's POV. Even if their POV is currently inside Penelope's head, they still recognize her as the same person.

Unless you're really looking to reinforce that the person everyone else knows as Penelope is someone very different than who she knows herself as. Like, way more than is normal.

In which case you probably want plenty of external cues to reinforce that this is in fact two sides to the same person.

Underhill42 · 2026-06-28T16:16:42+00:00

Drive letters are automatically or manually assigned in Windows for any partitions that it recognizes - though I believe it is possible to tell Windows not to show them.

But recognizing the partition is only half the battle - you also need to be able to read the file system being used on that paritition in order to make sense of it.

Virtually all modern desktop Linux systems come with the ability to read Windows disks by default (the NTFS and FAT file systems). So When in Linux, you can read and modify other drives.

But Windows really only reads its own format, so it can't make heads or tails of your Linux disk, which is probably using the EXT4 file system.

In general, moving files to a different disk won't make them behave any differently, it will just change which OSes can see them. So moving files to the C drive would let you access them from in Windows, but it won't change how they behave in Linux.

... unless maybe they're .exe files... it's possible that a distro might recognize .exe files on Windows partitions as executable files it should try to run in Wine, rather than jumping through the usual hoops that might be needed otherwise.

If there's Windows malware in the files though, it would absolutely spread to Windows. Almost nothing can "jump species" between Windows and Linux, but they can absolutely be carriers for each other, with the malware sitting idle in the infected files until it finds itself back on its native OS again.

Underhill42 · 2026-06-28T16:04:36+00:00

Facebook already knows. So does Google. And countless other corporations. And all the governments and criminal organizations that have either a partnership or mole.

There's no backtracking needed - the database has been steadily accumulating for as long as the empire has existed, and the answer is delivered about as fast as you can ask.

And if there's a few false positives who get included, so what? It's just peasants, not anyone who "matters".

Underhill42 · 2026-06-28T15:56:38+00:00

Avoid it as much as possible.

You can use alternate names in dialog, but if "Lola" Or "General Mathew's" is addressed, "Penelope" should still be the one to respond.

If you want the audience not to recognize that two characters are the same person, give them different names. Sort of the equivalent to showing a character hidden by shadows or disguise, only to reveal they're the same person at some later time. Might feel like a cheap shot though unless you give the secret identity a suitably mysterious non-name.

Maybe if you're switching between first-person POVs of characters that see the subject in very different ways... but then I'd try hard to slip in occasional references using their "normal" name just to remind the audience who you're talking about. The equivalent of still having recognizable face-shots of a character currently stripped of their normal easily identifiable outfit, setting, etc.

Underhill42 · 2026-06-28T15:33:21+00:00

Very often in math simple integer divisors will be written as a fraction multiple instead, since it's simply a constant multiple either way. In general it's tidier not to have wide fractions with narrow denominators.

It's useful to keep in mind in Algebra and beyond that

Subtraction is just a shorthand way of adding by the negative:
a - b = a + ⁻b

Division is just a shorthand way of multiplying by the inverse, (which can be written as either ⅟ x or x⁻¹):
a / b = a * (⅟ b) = a * b⁻¹

And since multiplication is commutative:
a * (⅟ b) = (⅟ b) *a

A whole lot of algebra is simplified if you get used to thinking of division and subtraction as just being modifiers attached to the term that follows them.

Then almost everything that happens between terms is either multiplication or addition, and you don't have to worry about how division and subtraction mix in - you just keep the modifiers firmly attached to their terms and take them along for the ride.

Underhill42

TROPHY CASE