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In the spirit of bringing life into the thread, I thought I’d share something a little different.
https://archive.ph/96KCm
A summary won’t do it justice, and I encourage anyone interested to read the linked article; it’s not long. In short, though, researchers checked out approximately 5 million stars (in our galaxy—close enough to look well at and potentially one day visit) for anomalous ratios of infrared heat to light. The idea here is that if a star is giving off a lot of light that is being captured, it will heat whatever is doing the capturing up significantly. This is suggested to be possibly due to either unusual debris fields around these stars, which would be unexpected due to their age (most planetary collisions happening early on in a solar system’s lifetime, and these stars being older)… Or due to large amounts of sun-orbiting satellites soaking up solar power, a Dyson swarm. Our exoplanet imaging is still very much in its infancy, and we have already discovered planets that seem to bear biosignatures. The latter explanation is plausible, at least.
This is pretty far from standard culture-war fare, but I suspect that there are enough rationalists and futurists here to find it interesting. There are also a few potential links:
This implies that there is either a way through the theorized AI apocalypse, or perhaps that silicon-based life continues growing after taking over from carbon-based life (the “biological boot loader” thesis). While I’m rather attached to my carbon-based existence, it’s at least heartening that in this scenario something is still happening after AI takes over; the spark of life hasn’t left the universe. Unless all that power is going to making paperclips, I suppose.
Does it make sense to enforce population control on a cosmic scale, discouraging humans from expanding to other stars to avoid conflict? Could the “dark forest” hypothesis make sense, where offense is favored over defense and civilizations hide as much as possible?
Mods, I apologize in advance if this is insufficiently culture-war adjacent to deserve posting here. I didn’t think it worthy of its own thread, and feel like it’s perhaps healthy for the Motte to have some fresh topics as well. I’m a devoted lurker and thought I should do my part.
Edit- My list got butchered. Trying to fix it, but it seems the method I chose of writing multiple paragraphs after a question is disfavored.
The appeal of alien life is the fantastical and the joy of discovery. We have plumbed the depths of the ocean to only discover funny fish and our stars are just gas and rocks. Limits of physics and biology mean that as humans we will be unable to really experience interaction with extraterrestrial life, all those entities are too far away for a return signal to be parsed by an original sender.
The more likely path of interstellar communication will just be civilization-scale updates, like space PBS. A more fun bit of trolling will be basically pretending to be god. The old video game Star Control had a civilization of spider people manipulated into being torturous lunatics because a race of pranksters in another galsxy used a hyperwave communicator to hijack a planetary broadcaster. With communication being only one way, it just descended into hilarity. Humans could be space gods, commanding aliens to worship all bipeds, but we will never enjoy the spoils of our devotees.
IMO that "just" is doing a lot of work there -- what discovery couldn't be dismissed as "just [containing category]"?
Astrophysics and biologists get a justified kick out of understanding our world and how it works in the larger tapestry of the universe, but the spoils of the Age of Discovery were 'can I eat it' and 'can I fuck it'. If exploring the ocean depths didn't give me super caviar and looking at the pillars of eternity isnt pointing me to the Orion Nebulae fuck factory, then I consider the effort a waste.
Don’t forget ‘can I make money off it’.
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I think it says something about us that everyone is so interested in aliens, to the point where any kind of speculative "maybe it's aliens" generates insane media hype. And people are willing to support millions of government research funds for this stuff, even though it's unlikely to ever pay off and has no practical purpose, and most people don't generally support that sort of impractical academic research.
This is not an original idea but- are "aliens" taking the place of religion in our society? It feels more "scientific" even though it's still mostly just faith, and you can choose whatever sort of alien-belief suits you best, and hang out with other believers to create art about it.
There was a guy on 90 Day Fiancée who explicitly said to his very religious fiancée that he doesn’t believe in God, but that he does believe in aliens.
Apologies for the Facebook link, couldn’t find it elsewhere: https://facebook.com/90DayFiance/videos/children-to-aliens-90-day-fiance-season-8/414612926588272/
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My experience is that a pretty big part of the Christian left(which I was raised adjacent to) gets very into aliens as a replacement for doctrine. Now obviously ancient aliens are stupid in a not-even-pro social way, but they’re a fairly common replacement for taking certain passages in genesis literally.
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I think they have. Aliens are given either by technology or by psychic powers the abilities of former polytheistic gods. They can create wonders in the heavens, they can gift us ideas and technology and revelations. And because they have an aura of the scientific about them, even things that we know make little sense get brushed aside because they’re advanced.
And like everything else, it’s used by people with something to gain from the belief. Space agencies and astronomers and astrophysicists use aliens to get funding. The military uses them to hide black projects. History channel gets views by claiming that every weird text in sacred books is really about aliens. It’s a cheap trick but it works where credulous talk of angels, gods, demons, fairies, and orcs would be mocked and dismissed as crazy talk. I find it rather instructive to mentally substitute “angels” in places where people are talking about aliens. Most of the time the story sounds insane at that point, almost exactly like a religion.
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You'll lose the indentation for numbered lists but you can at least keep the numbers you want by escaping the "." after the number like this: "2\." Ex:
1.
2.
3.
Thank you, that’s helpful!
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Propellantless propulsion flies in the face of the conservation of momentum. This is a law which is baked in the current Physics theories, including the standard model and general relativity.
From a theoretical perspective, it follows from the Lagrange function being independent under certain coordinate transformations with Noether's theorem.
The steelman version of this propellantless propulsion would be the claim that of course momentum is conserved, there are just previously undetected particles or fields which carry momentum. Just like a plane can accelerate while staying at the same height without violating the conservation of momentum by transferring some momentum to the air with a propeller, a spacecraft might do the same. Of course, the particles could not be reacting with anything else (like satellites or these fancy detectors we use for dark matter search), otherwise they would have been found long ago. A fundamental part of the universe being discovered by chance through an commercially interesting engineering application seems unlikely -- it would be like if Edison had created the light bulb and physicists had only discovered electricity afterwards to figure out how it works. (By contrast, my priors for observing complex systems exhibiting unexpected behaviors which will surprise physicists are much more relaxed, high temperature (that is, liquid nitrogen) superconductors were a total surprise, and the early experiments with heavier-than-air flight probably took place before we had any idea how a plane is generating lift.)
The priors for that would at least be slightly higher than "Archangel Uriel personally pushes the spacecraft forward", but still lower than for room temperature superconductors or even room temperature fusion.
The best way to convince the world that the "emdrive" works would be to put one in LEO in a cubesat. Even if you can only generate a very moderate thrust from solar power, the ability to create that thrust continuously will integrate to a tremendous delta v. A year at a thousandths of Earth surface acceleration would work out to 309km/s delta-v. Within three years, your spacecraft would pass Voyager 1 in distance. Humans have some capabilities to track satellites, so we could check easily enough.
Of course; anything that works (beyond VSIMR or solar sails, as another commenter helpfully pointed out) requires some law-of-physics updates. But I will point out that this is exactly what is claimed.
I’m not strongly arguing for this being The Real Deal; as another commenter pointed out, put it on a satellite and prove it. Rather, my interest in this is as a thought exercise: consistent force production from electricity allows us to do all kinds of wacky stuff, up to and including interstellar travel on reasonable timeframes, pursuant to your definition of reasonable. 1G acceleration, as is claimed in this particular instance, would get us to Alpha Centauri in a little over six years; 12 years if we are slowing down at the halfway point. This is well shy of “generation ship” type speculation, and would turn intersolar travel into something feasible in a lifetime.
Now, hefty grain of salt and all that. I’m skeptical myself, and recognize this is extremely speculative. Not only are there large engineering challenges in building such a spacecraft (or proving that one of these propellantless engines can produce thrust), there are also a whole slew of known unknowns (interstellar hydrogen or small molecule impacts at an appreciable percentage of C?) and unknown unknowns.
At the same time, it also solves some problems. Consistent acceleration, likely even under 1g, removes a lot of the problems of extended stays in microgravity, and if we’re hypothesizing advanced extrasolar civilizations anyways… Then it stands to reason that we would not be the only ones who would discover such things. It would “raise the ceiling” on intrastellar travel, so to speak.
I’m happy to be able to discuss it. While my own priors are low for any individual ‘game changing technology’ coming to fruition, we do know there are yet-unexplained physics; we live in exciting days, in both the positive and negative sense, to be able to more seriously start investigating these fringes.
Even if we grant them that they have discovered a new thing which can carry momentum, I am kind of puzzled about the implications for conservation of energy.
Friction and air resistance aside, the most effective method to convert energy into momentum of your vehicle is a railway (or car). The other mass involved in the conservation of momentum is Earth, which is much heavier than your train, so almost all of the energy you invest ends up as kinetic energy in your train. We know from high school physics that the energy you have to invest to reach velocity v is E=m/2vv.
Rockets are a lot less energy efficient than that. Because their momentum-balancing mass is much smaller, they end up with most of the energy being carried by the exhaust. Tyranny of the rocket equation and all that.
Photon drives powered by onboard reactors may or may not fall under some weird relativistic version of the rocket equation (after all, your reactor will become slightly lighter as it provides energy), but are in any case laughably inefficient.
A drive which provides a useful constant, rate of acceleration while using a constant amount of power would be better than the train, eventually, thereby violating conservation of energy.
Another way to think about it: If you are using undiscovered massive particles (perhaps dark matter) to dump your momentum into, the rest system of these particles will define an unique frame of reference. If you are in the rest system, you can accelerate very efficiently with your magical drive: just suck in particles and expel them with a tiny velocity (say 1m/s) to carry your momentum. If you do that for a while and now move through the particles with 10 km/s, you will notice that your job becomes much harder: to carry the same momentum, you will have to accelerate the incoming particles, which you see at 10km/s, to 10.001 km/s. This costs a lot more energy than accelerating them from 0m/s to 1m/s. (You will also see more particles per time, but this will not save you, fundamentally, the amount of energy you require to dump a marginal amount of momentum (dE/dp) will become very unfavorable.)
This of course suggests another test for the emDrive: Michelson-Morley experiment, dark matter edition. Measure the thrust per energy (probably in z direction, so don't pick the poles?) at different times of the day and the year, so that the relative velocity of the particles in the direction of the thrust is different. If you get fluctuations consistent with Earth moving through some particle field, this should be enough for at least one Nobel.
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Whatever happened to Heim theory? Did it get disproven?
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To be fair it's not like that kind of stuff never happens. A lot of the history of semi-conductors is engineers trying various random things intuitively to get a particular defined effect and only explaining why that worked after the fact.
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Photons have momentum. If you're collecting light that's hitting your craft always at the same angle this momentum has to be transferred somewhere, and your craft is this somewhere as there is nowhere else for it to go.
Yes they do. Wikipedia points out that the force is (1/c) times the power, and helpfully converts 1/c to 3.34 Newtons per Gigawatt. The article also helpfully does the calculation for the solar radiation near 1 AU (i.e. Earth) and comes to a value of ten Micronewtons per square meter.
If one wants to use this force, the best thing one can do is have a very large and very light mirror, which is better than first taking the momentum of the suns photons on your solar collectors and then sending a small fraction of that momentum out in the direction you actually want to accelerate in. This is not completely hopeless: metallized Mylar foil might weight some 50 micrograms per square meter, so a space craft where most of the mass is in the foil might accelerate at 40 centimeters per second squared (though there are some constraints on the direction, similarly to sailing). Of course, having a spacecraft with two hectares of foil per kilogram of payload might be difficult from an engineering point, and micrometeorites might become a problem. I would probably play a Kerbal mod which adds Kerbol radiation pressure and giant sails, though.
Or you could actively shine an Earth- or Moonbound laser on your spacecraft.
In general, there is a tradeoff between getting the most momentum out of your propellant mass, which benefits from higher exhaust velocities on the one side (with photons being the optimal choice, and ultrarelativistic ions only slightly worse) and getting the most momentum per energy invested, which favors throwing out a huge mass at minimal velocity. For propulsions where the energy source is decoupled from the reaction mass, such as ion drives, the sweet spot seems to be at a mere 20-50km/s -- which is far away from the 300,000km/s you would get with photons.
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If we discover advanced alien civilizations existing doesn't that actually lessen the evidence for the Dark Forest theory? Something like massive infrared indicators imply that they are not hiding. Dark Forest theory implies hostile and hidden. @hydroacetylene
If this is a valid way of spotting alien civilizations. I think it becomes very important to look at groupings of stars. A cluster of 100 stars all having this indicator right next to each other suggests an expanding and potentially grabby aliens. If its just 100 stars spaced out randomly in the galaxy then that maybe implies that expansion and colonization is not something anyone has bothered with. If there are 100 stars with this indicator that are sort of close to each other but not exactly next to each other then it might imply islands of habitability (explained in this video). I also think if the candidates are randomly dispersed it also means its more likely that this explained by a natural phenomenon (like planets crashing and causing a debris cloud).
I believe propellant-less propulsion is possible and just not widely explored enough. The physics limitation is that you just need something to push or pull on that isn't the craft itself. We know of forces already that do this. Gravity and electromagnetism. Maybe we'll find other forces that do this. Maybe we will find something else to push on in space.
If there’s two prisoners, it’s semi plausible that neither of them defects. If there’s 200 prisoners, it only takes one defector.
And if we assume that even advanced civilizations are mostly planet bound, and that there’s physical reasons limiting the ability to chart exoplanets, then it’s pretty easy to miss an extermination attempt. Maybe finding the homeworld of these aliens is difficult, even if we can tell which star. Can we predict the actual location of known exoplanets well enough to launch a missile which can’t course correct? I’m betting no. Not to mention any individual case could be something other than a civilization, even if it’s phenomenally improbable they all are.
We should adopt an attitude of reflexive paranoia towards possible aliens until they are known to be friendly, and use this as an impetus for dispersion.
If no one is doing intersolar colonization then I really don't see a need to worry.
Hell if someone's fired a sleeper ship at us at the point of our first radio waves and it's not going to get here till some arbitrary future year I don't really consider it of major concern.
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If we can discover multiple advanced alien civilizations at our current tech level, Dark Forest theory is annihilated. Better said that the Fermi Paradox would stop being a paradox.
Personally, I wish people would stop taking Cixin Liu's plot device in Three Body Problem as a serious speculative hypothesis. The books were an exploration, in their own way, of the problems Scott mulled over in Meditations on Moloch, and the Dark Forest was a kind of literary device for the nihilistic endpoint of progress and memetic competition.
and
These are at the heart of what the books are getting at.
[url=https://en.wikipedia.org/wiki/The_Forge_of_God]Greg Bear[/url] came up with it long before anyway. And Fred Saberhagen as that article points out, though I don't know how explict he was about it.
I've read some of Saberhagen's books. And yeah, before it was "The Dark Forest Hypothesis" it was "The Berzerker Hypothesis" so he should get some credit for coming up with it first. But they're very silly space opera books, lots of action with basically no deep thinking. They're not meant to be taken too seriously, so I can see how people slept on the idea.
Still, as crazy as it sounds, there is a certain elegance to the idea- it solves the "it only takes one" problem. Like, maybe most aliens just don't want to expand, or don't want to build megastructures, or are using tech that is somehow hidden from us. That's all fine, but you'd think there'd be at least one similar to us so that we could detect it easily. But in the same light, maybe 99.99% of aliens are peaceful, but there's just that one group of assholes who built berzerker probes and wiped out everyone else (maybe including themselves).
Eh, not really; a lot of them are basically "puzzle" stories, where the protagonist has to outsmart the berzerker.
Anyway, that's not a complaint you can make about the rather heavier in tone Greg Bear books. Bear may have called it a "vicious jungle" rather than a "dark forest", but it's the same thing.
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I just found the quote I'd misremembered as being by either Niven or Pournelle, but which turns out to be from "The Killing Star".
I won't dump the whole thing because most people will be familiar with it, but it's the one that ends with "There is no policeman. There is no way out. And the night never ends."
You can tell it's from 1995 because the worst imaginable cosmic horror is to be stuck in NYC's Central Park after dark.
So the idea has been bouncing around in science fiction for decades, rather than being slept on.
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I was under the impression most people are buzzing about it lately because of its prominent featuring in a popular scifi. The specific term "Dark Forest" was added to the Fermi Paradox Wikipedia page in 2016, specifically referencing Cixin Liu. On the other hand "It's dangerous to communicate" was listed as a possible solution well before that. Perhaps I'm overstating my case.
I do think in the novels it's a parable.
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I've never read Bear, but Forge and Anvil have been recommended several times. Are they any good?
I loved saberhagen's berserker series. Templar Radiant is brilliant, and The Annihilation of Angkor Apeiron is a paragon of the classic pure concept scifi short story.
Yes, they are. The ending of Forge is one of the more indelible moments I've read in sci-fi.
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Until I put my fingers in the nail marks, and put my hand in its side, I will never believe.
And Neil deGrasse Tyson said unto him: more blessed are they that have not seen, and yet have fucking loved the science
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My understanding is that propellantless drives ("swimming in space") are permitted by the current Laws Of Physics. This approach is very different from the one taken by the propellantless propulsion efforts, though.
Don't most of these still require exotic matter? Trading breaking conservation of momentum for negative mass never really sounded to me like a gain in credibility.
Not "swimming in space" – that just requires changing your shape.
There are "warp drives" that use exotic matter for superluminal travel, but there is also at least one proposal that uses no exotic matter, albeit only for slower-than-light travel.
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In the event of discovering many advanced alien civilizations, proceeding as if the dark forest hypothesis is true becomes a priority, because it’s game theoretically optimal in an environment where communication and thus cooperation is impossible, and functionally no warning would precede a dark forest attack due to relativistic kinetic impacts being the obvious default strike method. That means civilizational dispersion becomes a top priority, and whatever we do, we should not beam some ‘hi, we’re friendly!’ Math problems at these stars.
You'e talking as if developing replicator technology and getting as far and as fast off from the rest of you humanity wasn't the default position of every person with an ounce of self preservation.
People are insane these days due to being disconnected from actual material reality. It's going to get far, far worse with more wealth. Either we get thought control and become some weird hive mind, or people will be getting ever more insane because they can and because our minds were not designed or evolved to cope with modernity.
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Assuming our current understanding of physics holds, much of this doesn’t matter. If there are Taelons 100 million ly away from us, it is highly unlikely they’d care about us. We don’t have anything they don’t already have. So hiding makes no sense — it would take them millions of years to get here, for no gain. You can find most of the material in our solar system in thousands of other places much closer to the alien planets and can extract them without having to mess with people or other animals.
And from the other end, it’s all speculative. The aliens are undoubtedly weirder than we can possibly imagine, and our views on culture and government are largely based on our own history. And I’m not sure what these aliens have to do with AI. Maybe they solved the alignment issue, or maybe they destroyed all their AI and have been huffing Spice. They might have stalled on on technology before AGI. We don’t know anything and frankly can’t know anything. We found some odd chemical signatures, that’s it. Trying to pointlessly speculate on what this means for the future of space travel, propulsion, AGI, or alien human relationships is premature in my view. This might be something interesting, but it might not.
Milky way diameter is only around 100 thousand ly, the closest Andromeda galaxy is 2,4 million ly. Even Voyager is travelling around 1 ly/18,000 yeas so it can get to the edge of the galaxy in around 900 million years. Parker Solar Probe, which is fastest moving man-made object has ten times the velocity, so it could travel to the edge of the galaxy in tens of millions of years.
Any sufficiently old civilization - let's say tens or hundreds of millions of years old - could reasonably have a probe in every star system in the Galaxy even with our current propulsion technology with no problem and it could even explore other galaxies if it is 1 billion years or older.
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We extensively study all sorts of animal and microbial species here on earth, simply out of curiosity, even though these species don't "have anything" for us. Sometimes this research leads to medical advancements, but usually it doesn't. Most academic research is in the same boat. There's no "practical" reason to study obscure religious treatises from late antiquity, or the cultural practices of a hunter-gatherer tribe in Africa, but people do it anyway.
Maybe. But if they are, then that means that we'd be impossibly weird to them! Which would make us rather more interesting.
Of course, it's an open empirical question whether aliens would find any value in studying us or interacting with us. Maybe they would, maybe they wouldn't. But thinking that humans couldn't possibly be interesting to a scientifically advanced alien intelligence is just as much of an unfounded bias as thinking that humans are always at the center of the universe.
Studying and interacting is much different than expending considerable resources on something, which in turn is much different than waging war or making large economic investments in something. Sure, we spend money on researching things out of curiosity already, but it's not a lot. Numbers are hard to come by, but one figure I saw says we spent about $7.2 billion on botanical research in 2013. However, the context of this figure was talking about money spent on crop science research, and I'd be willing to bet that the money spent on projects like some professor studying rare ferns of Appalachia is much less than what we're spending on more practical applications. If an alien civilization were to visit earth from the distances described, it would be an incredibly costly mission with no guarantee of success. My guess is that if they wanted to study us they'd send unmanned vehicles first, then maybe a small research party like at the beginning of E.T. I highly doubt they'd come here with cargo ships ready to exchange resources for technology, let alone bring an army to mount a full-scale invasion. After all, we've been sending stuff into space for 60 years and we still haven't got past the curiosity stage yet, with the exception of satellites that are within driving distance. We certainly haven't gotten to the point where it makes sense to start mining the moon or something similar, and that's practically right on top of us in astronomical terms.
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