Naturally occurring black holes do not have measurable magnetic fields. Their accretion discs may, but a micro-black hole would not have a discernable accretion disc.
To mess with black holes, you need to manipulate gravity directly. If you can do that, you no longer need natural black holes — just make your own.
Also, good luck using a magnetic field to capture an object weighing a trillion tons moving at 20 km/s.
Edited by Fighteer on Aug 20th 2024 at 1:38:56 PM
"It's Occam's Shuriken! If the answer is elusive, never rule out ninjas!"New Scientific theory: Dark Matter is made from the remains of leftover nets with the density of black holes made by ancient civilizations trying to catch black holes.
This pairs with my other theory of reality, which is that the Big Bang happened when alien scientists successfully recreated the conditions of the previous Big Bang.
Clown To Clown Handshake Initiating...
You stole that from an xkcd comic.
(Assuming that xckd didn't steal it from someone else already.)
More or less. Dark matter cannot interact electromagnetically and as such does not form or participate in accretion discs. (Incidentally, the density of matter in such discs and/or in stellar remnants is enormously higher than anything we can reproduce on Earth and should have lots of dark matter interactions if such things are even possible.)
For a black hole to swallow it, dark matter must directly intersect its event horizon, because otherwise it would miss and escape on a hyperbolic trajectory. I'm not even sure if dark matter could accrete in a neutron star or white dwarf, since it would have to be stopped via collisions with the regular matter inside.
To be sure, black holes, especially supermassive ones, must have swallowed quite a bit of dark matter. It's mathematically certain. But whether dark matter can accrete like normal matter is unknown and strongly depends on its inherent nature.
If dark matter is capable of interacting via the nuclear weak force, then there must be a non-zero number of cross-sectional collisions between it and regular matter, and stellar cores and black hole accretion discs are places where we'd expect that to happen. If it only interacts gravitationally, then it would pass right through a neutron star or white dwarf without noticing.
Edited by Fighteer on Aug 20th 2024 at 3:43:20 PM
"It's Occam's Shuriken! If the answer is elusive, never rule out ninjas!"Dynamical friction
means that even particles that interact solely gravitationally can be accreted - the energy is then dissipated by the stellar body matter via non-gravitational processes, I guess. Also, "only interacts by gravity" isn't a required property of dark matter - there might be non-gravitational interactions that aren't electromagnetic and thus can't produce light, hence making it invisible.
Edited by SeptimusHeap on Aug 20th 2024 at 9:48:18 PM
"For a successful technology, reality must take precedence over public relations, for Nature cannot be fooled." - Richard FeynmanOkay, but cosmological evidence shows no sign that dark matter undergoes dynamical friction to any significant degree. At least that's my understanding.
"It's Occam's Shuriken! If the answer is elusive, never rule out ninjas!"Pretty sure that it's not physically reasonable for dark matter to not engage in dynamical friction. Nothing here supports that, either
. But we are increasingly getting offtopic, so I'll stop here...
So a setup I'm working on, I wanna see what other perspectives I could get on what scenarios could go through.
It goes like this, interdimensional aliens open a portal in a populated urban environment and march through, large 8 foot tall warriors with thick bulletproof hides and sharp claws on multiple arms then set about attempting to begin taking the area as a first foothold for their empire. While they have the claws those are just for close range as they do carry ranged weapons and have fighting vehicles akin to APCs or tanks.
The first contact with them goes poorly, naturally, and so these invaders do end up being repelled but not without massive collateral as a result. Another group later appears in another city on the globe and a similar situation occurs.
The setup is that these invaders, named the Legion for now, are attempting to of course, invade Earth and conquer it for whatever reason. The idea is dense urban environments for combat and while I have a few ideas myself I'm open to hearing other suggestions as to how humanity starts fighting them off in tight corridors and streets.
I assume they aren't immune to high-caliber weaponry and/or explosive shells, so unless they can invade simultaneously in the tens of thousands, they're a problem but not an insurmountable one.
Their advantage is the ability to show up anywhere at any time without warning, meaning that it's impossible to stage defenses in advance. But other than that, they sound like conventional urban warfare combatants, and we have lots of practice in that as a civilization.
The concept sounds remarkably similar to how the Combine invade Earth during the Seven-Hour War in the Half-Life universe. The difference is that they show up everywhere, all at once, with such overwhelming force that there is no time for governments or militaries to organize a defense.
Fundamentally, Earth has millions of troops staged all over the place and enormous amounts of warfighting materiél, so you need an equivalent amount of stuff to beat us.
If the portal-based invasion occurs gradually or ramps up over time, I'd expect scientists to work frenziedly on detectors to gain early warning for when one will show up, and to try to disrupt and/or duplicate the technology.
Edited by Fighteer on Jan 8th 2025 at 9:14:03 AM
"It's Occam's Shuriken! If the answer is elusive, never rule out ninjas!"Definitely not invading all at once for the Legion. There's a reason for that and it boils down to "Internal Politics" on their end, they could invade the entire Earth all at once, they've conquered other worlds so they have the manpower. But internal politics and bidding for a chance to invade to become the next great ruler of their empire is the thing preventing them from doing so.
I had also considered detectors to start tracking where the Portals open up for more rapid response.
I have questions about the politics of an empire that conquers planets via portal invasion but seems willing to dump foot troops through to die uselessly.
"It's Occam's Shuriken! If the answer is elusive, never rule out ninjas!"Complacency and growing noble houses after successful previous invasions hit more primitive worlds largely. The empire is powerful but has gone on so long that it's started to hit problems, growing houses within have begun trying to push for new seats on the Consulate and attempts to become the new Emperor of said empire to the point that they're fighting each other just as much. Projections from previous looks at Earth had shown it to be far more primitive than it is now.
Should the Empire get its shit together they'd open every portal they have and dump in every single house and their standing forces all over the globe, from their biotech augmented warriors, their war machines, etc.
My immediate issues are basically:
The aliens don't seem any more impressively equipped than the humans so the fight is going to be very even, raising the question of why they even do it this way.
What stops the aliens from sending nukes through.
The aliens seem comically overpowered as an enemy. Even if the empire fragments, a single fragment could instantly conquer earth.
if the empire is on the edge of civil war, who has time to invade planets? like, at all?
If it's truly an empire, it could never afford to send all troops through, it would need a substantial military to keep it's empire in check. Conversely, it would have enough of a military that even a light tribute from client states would wreck Earth.
I feel like it would be simpler if this was just some local alien governor, stuck in this rat-race to civil war, decides to annex Earth to increase his power but the plan goes awry. Like, the guy has neighboring or rival governors who he can't beat directly, so he sets his hope on a quick conquest of Earth to begin the "real" battle.
That works, and this is why I bring up these ideas, to have them kicked around.
So it's a local governor as the Empire is on its way to civil war. Fits well, the Empire is very "Fall of Rome" in style.
The idea with these guys was to give them a sense of power, something that would make it so that humanity does have to push and innovate as the invasions become more frequent, while making it clear they aren't just rolling over us with all portals everywhere and winning in short order ala the combine.
Empire In Decline, Multiversal Mechanics necessitating only short invasions to set up an anchor, or unknowable motives were the three I could come up with myself.
Edited by EchoingSilence on Jan 12th 2025 at 9:44:21 AM
Your description basically screamed "roman empire" to me so i creatively stole the idea. The equivalent of some roman centurion or governor, deployed at the germanic front, deciding that if he takes the nearby tribe he could have a decent position of power (and triumph!) to go do bigger things.
The main issue with this is that, based on your description, the escalation is going to happen *rapidly*. You cannot get the main government involved in any way or humanity just...loses. Instantly. But the logic for the governor is equally rigid: quickly take Earth or lose. After a failed decapitation strike, the next strike would be a much bigger and forceful attempt, and after that would follow a desperate all-out attack.
Actually, the funniest outcome is that Earth could survive that attack (depending on the exact size and political environment of the aliens), do a counter-invasion and become the local owner of an alien province. Depending on the exact xenophobia of the aliens, this can actually make Earth a member of a galactic organization basically by failing upwards.
Decline isn't necessary. But empires require an imperial core that extracts wealth from it's imperial periphery, and this is an imbalance. Periphery can become core, differences in capabilities will erode. If the empire just went through an expansion phase and now has a lot more territory to oversee, newly empowered generals to keep happy, and more imperial underclass to surpress, there would not be a lot of political power left to start big new invasions. Similarly, governors or generals may sit on too many people to keep happy and decide that the old invade-and-pillage system works fine and try it on their own.
The only real necessity is that the empire is busy with itself, or at least elsewhere in the galaxy.
Edited by devak on Jan 12th 2025 at 4:21:49 PM
See, if I were a planet-conquering alien overlord with portal technology, I wouldn't send legions of troops to die in urban warfare. That seems a bit wasteful. Rather, I'd send strike forces into the offices and/or homes of every major world leader at once, snatch them up, and force them to surrender to me. Or, y'know, offer bennies for joining the team voluntarily.
"Join us and we give you all this cool tech, help you solve your planet's problems, and generally guarantee that you keep getting elected. Reject us and everyone you know and love will get bombs teleported into their bedrooms, and/or we'll dig up those videos of you fucking goats and display them in Times Square."
I realize that space opera demands spectacular battle scenes, hand-to-hand combat, a plucky underdog resistance fighting the alien oppressors, and so on, but it's grotesquely unrealistic.
Then again, if this empire is one of those stagnant, decadent ones, sending ground troops to die by the thousands for token "conquest" may just be how the leaders stay in power. The inefficiency could be the point.
To demonstrate this, I envision a scene where a subordinate suggests my first idea above and the leader admonishes them and/or has them executed for daring to challenge the orthodoxy.
Edited by Fighteer on Jan 12th 2025 at 12:54:05 PM
"It's Occam's Shuriken! If the answer is elusive, never rule out ninjas!"This is why i would write it so that the invasion force goes wrong (Or unexpected) and so they appear in locations other than major populous cities. After all, the portal technology is at its most powerful when it's a surprise, so you cannot do infinite scouting. And depending on the distances involved, they may have information that is out of date or incomplete.
It's also why i would write in a measure of urgency. Yes, the alien general could probably do a more cautious approach but the invasion of Earth can only be done in a rather narrow time window of opportunity. So it requires a measure of improvisation, but the aliens are confident they can do a decapitation strike. When that strike fails, there would be a second more powerful strike. If that fails, the only two options left are to back off (risking Earth developing into a major threat and antagonist, and also a potential asset to your enemies) or to go all-in.
While i would argue cooperation would obviously be vastly more useful, a militaristic society may not tolerate foreign cooperation and seek dominance in stead.
If this is a Rome expy, then internal politics may be the deciding. Perhaps several provincial governors are in a race to win the next war, because that would give them an advantage back in the Imperial Court, but in their haste, one of them badly underestimates how hard it is...
I'm done trying to sound smart. "Clear" is the new smart.A Rome Expy could also draw parallels to the often outdated and inflexible battle tactics they used too.
Say the portal invasion idea has proven great before against other enemies. But against a foe with extensive experience at Urban Warfare (Earth) they suddenly find themselves in a losing fight that they aren’t used to.
I had been thinking extensively about the rules of the portals and why they end up in Urban Environments, and best answer I have that would provide some interesting situations on both ends is that the targeting system for them tends to go for areas with denser electronic noise. You can open a portal anywhere, but for more accuracy the area with more electronic signals acts as a better beacon.
Or you could just simply have them open the portals there on purpose out of simple, brutal pragmatism: they know the defenders have WMDs, so they're deliberately deploying their forces in such a way as to maximize collateral damage if/when the defenders do try to take the easy way out.
"Are you ready to butcher a thousand of your own for each of us?"

This is pretty much a space opera idea so it's almost certainly not real world functional, but I could see a story involving manipulation of the magnetic flux tube between Io and Jupiter to create a vastly powerful magnetic net to catch micro-black holes in.