"Imagine the exotic "pollution" caused by civilizations which are advanced enough to tinker with the fabric of spacetime, but not advanced enough to understand (or care about) the long-term consequences of that tinkering"

That's fun science fiction, as others have pointed out, but in terms of real science, at the moment that's just a sort of subtle way of anthropomorphizing the universe and projecting human experience far, far beyond where it is applicable. Einstein's equations for spacetime evolution don't have anything that looks like "pollution" in them. There's no "stress term" for "space time that has been put through the wringer and is broken now". Black holes do not seem to leave "broken space" behind them or anything like that; indeed, "leaving broken space 'behind' them" would be an incredibly ill-defined term. In what preferred reference frame does your "pollution" take place in?

The only real concern is if there is some way to violate the conservation of energy, as real space does seem to do that at large scales at the moment. In that case someone might explode something, potentially large enough to make a mess of a galaxy or more. But we don't have even a hypothetical example of how to do that; just because the universe is violating energy conservation does not mean there's any conceivable organization of energy we can create that will do it, if the reason conservation is being violated is the injection of energy from some other effect or something.

"In what preferred reference frame does your "pollution" take place in?"

Pollution would be any undesirable side effect and there are plenty to be imagined in these scenarios.

Your comment strikes me a bit like a chemist denying environmental pollution as it's all "just chemicals."

"Your comment strikes me a bit like a chemist denying environmental pollution as it's all "just chemicals.""

Chemicals admit of a form of pollution when they form themselves in ways we don't like. Spacetime doesn't have that sort of memory, excepting exceedingly weak gravity waves, for which it is basically impossible for those to ever be your biggest problem (if not simply impossible for those to really be a problem). There's no spacetime equivalent to dumping a nasty chemical somewhere, and a hundred years later that chemical is still there hurting people. Spacetime doesn't work like that.

You're basically anthropomorphizing, thinking that there just has to be a way for humans to screw this resource up because humans are just that icky and gross, because cynicism and fashionable misanthropy. There isn't. Not in the real math. There's nothing humans can do in the real math that we know that the universe hasn't already done a couple dozen orders of magnitude larger than we could ever dream of. If space was going to "rip" or something, it would have already. It doesn't. In fact, in the real Einstein field equations, space very, very, very aggressively doesn't rip or suffer any other such problems. Any attempt to introduce such defects results in those defects immediately (and often quite energetically) undoing themselves. That's why when you read about real wormholes, for instance, the story always ends with the wormhole collapsing and exploding before anything, even light, could possibly traverse it.

Real math may change, in which case this answer may change. However, I expect that by the correspondence principle, even the ultimate unified theory of everything is unlikely to have an outcome where suddenly all this stuff is possible. Whatever the ToE is, it's still going to reduce to General Relativity in the large scale.

The pollution would be internal to the civilization, not something lasting of import to outsiders. The ability to warp spacetime to the point of violating causality, time travel, might be a death nail for a civilization. Literal prescience could be dangerous. As such technology moved though a society it could be described as a pollution.

Maybe such technology involves the creation of unnatural structures, something like stable wormholes on human scales. If those structures outlived their creators, areas of space containing them could be considered polluted, or at least dangerous to later civilizations.

Douglas Adams did some thinking on this for Hitchhicker's, that time travel caused cultures to stagnate and eventually degrade for lack of motivation.

> The ability to warp spacetime to the point of violating causality, time travel, might be a death nail for a civilization.

death knell

I know you probably know this, and I don't mean any disrespect. I'm writing this for other people who don't speak English natively (I'm also not saying you're not a native speaker, just that I'm not). I don't want anyone to go away with the wrong idiom.

"You're basically anthropomorphizing, thinking that there just has to be a way for humans to screw this resource up because humans are just that icky and gross"

I said nothing of the sort. You are, perhaps, confusing me with another poster.

"There's no spacetime equivalent"

Nonsense. The obvious example is emitted radiation, though any type of energy, matter or field byproduct might fit the bill.

Pollution is undesirable on earth because it causes us harm from which we can't escaoe or reverse.

The idea of "polluting" spacetime makes no more sense than humans "polluting" the natural organization of air molecules by displacing them by existing, or polluting the natural distribution of entropy by making decisions.

It's just bringing politics into a place where it doesn't belong.

Pollution, by definition, is something that causes harm:

"the presence in or introduction into the environment of a substance or thing that has harmful or poisonous effects."

I have no idea why you have this idea that polluting is some politicized term.

Pollution is intimately tied to politics because most inhabited property is owned, which means it's regulated by some governmental systems having varying degrees of regulation and penalties for pollution. I have no idea why that has to be explained to you.

Being able to point towards a subset of pollution which is regulated does not necessitate the entirety of pollution as regulated/political. Pollution isn't defined by political fiat.

Your argument also doesn't hold considering that in the case we're talking about right now, the vast majority of spacetime is not inhabited nor is it regulated by anybody. Yet we're still able to talk about pollution because pollution in no way is tied towards a politicization of the conversation.

One could even go so far as to say you've polluted the conversation by including this "but you're making it political" distraction.

You admit space is uninhabited. Your unnecessary and petulant copy/paste of the definition of pollution includes the words "poisonous" and "harmful". Which isn't possible to do to an uninhabited area. I have no idea why you keep forcing such a contrived idea, other than to draw in a political "bad humans, always polluting" message. Anyway I'm done with this silly conversation. Have fun

Much of our terrestrial pollution took place in "uninhabited areas" which decades later became inhabited. Your comment is reminiscent of 19th and early 20th century attitudes toward pollution.

It's true that it isn't a problem -- until it is.

I'll acknowledge that harm and poison require a reference for where the harm is done, but I don't think it requires human interaction necessarily.

We are able talk about harm being done to insect populations or coastlines or any other inanimate objects. Again, humans, and their politics, aren't necessary.

I don't find my quoting of the definition as being petulant. I was wanting to frame the conversation around a shared definition of the word rather than asserting requirements.

Putting "pollution" in quotes was to substitute it for "waste", or byproducts, or side effects, that may or may not be undesirable for some species somewhere and somewhen.

I just imagine that once you do work at such scales, and with such strange materials and results, then the "waste products" of that work would be just as weird.

Also, would black holes not be considered "broken space" themselves?

"Also, would black holes not be considered "broken space" themselves?"

Even that is really an anthropomorphization. They don't "spread". They don't "damage" the space around them. They don't leave behind anything as they pass through space. They aren't having the effects that people imagine when they think about "pollution".

There’s no ‘nuclear holocaust’ term in the equations for atomic physics, but nonetheless it is an undesirable consequence of screwing around with nuclear weapons.

By violating conservation of energy are you referring to dark matter?

Dark energy. Generally speaking, energy is not conserved in general relativity: http://www.preposterousuniverse.com/blog/2010/02/22/energy-i....

According to General Relativity, energy on our Universe isn't conserved.

He could just be referring to the existence of matter at all to be fair. Violations of thermodynamics are required for anything to exist at all.

This is very similar to Strugatsky Brothers' Roadside Picnic[1], a book which inspired, among other things, Andrey Tarkovskiy's film Stalker and the S.T.A.L.K.E.R. video game franchise.

[1] https://en.wikipedia.org/wiki/Roadside_Picnic.

Thanks for the recommendation, I adore the Stalker film.

>Imagine the "pollution" caused by civilizations which are advanced enough to tinker with the fabric of spacetime, but not advanced enough to understand (or care about) the long-term consequences of that tinkering.

I once had, and never used, an idea that the consequence of using such technology was to accelerate dark energy, so that the more civilizations used FTL travel, the greater the energy requirements became. As if seafarers had to deal with the oceans expanding just a bit every time they were crossed.

> so that the more civilizations used FTL travel, the greater the energy requirements became.

That sounds like a recipe for some terrible monopolization by the first few civilizations that manage to achieve FTL:

Those who are the earliest to expand into the universe, would have access to the most resources, so they would be the only ones left who can afford to use FTL anymore, while younger civilizations may never have a chance to get out of their home stars.

> Those who are the earliest to expand into the universe, would have access to the most resources

Eons ago, the universe was room temperature. I've always wondered how an intelligent species adapted to that time would perceive our universe.

Likely, he wouldn't. The window in which the universe was roughly room temperature is very narrow in astronomical terms, so even if life did form during that period, it probably would not have been able to form even animal life, much less intelligent life.

If everything was happening faster back then, and if we assume there were more interactions between everything and more kinds of interactions back then, then life and intelligence may have evolved faster too.

There's no reason to expect more kinds of interactions; the laws of physics were the same then as they are now. It also isn't clear that there would be more interactions. Galaxies hadn't formed, even if we stipulate that stars could have. So, the good: wherever a planet forms it should be warm enough for life (although it could still be too warm if it's close to its parent star). The bad: There are probably far fewer planets and ingredients for life and there is precious little time. For reference, for intelligent life to form during this period, it would have had to have done so at a rate of about 500:1 compared to the evolution of homo sapiens on Earth. Even life evolving in this narrow window would be difficult (~50:1 compared to on Earth).

That also sounds like a recipe for maintaining causality as in the faster you are trying to go to more you’ll expand space time maintaining the luminal speed limit from the point of view of an observer.

>That sounds like a recipe for some terrible monopolization by the first few civilizations that manage to achieve FTL:

Yeah, that's where the "evil empire/East India Trading Company but in Spaaaaace" was going to come from. I wanted to use hyperspace/FTL as a vague metaphor for a scarce but crucial resource like fossil fuels (or whale oil, back in the day.)

> "evil empire/East India Trading Company but in Spaaaaace"

I think it would be much more sinister.

The FTL controllers would be seen as gods by species who have yet to leave their homeworld. Every civilization within their sphere of influence would be either have to be their allies, thralls, unable to move around in the galaxy unless they get piggyback rides by the FTL barons, or engulfed and extinguished by them.

Imagine if we in the real world found out that there was no way to explore the universe we've been observing for centuries, unless we allied with some alien species that does not, can not, have our best interests on their minds.

Interstellar travel would require resources, and resources would require interstellar travel..

To go against the FTL species you would need to control at least as many planets as they do, and to control that many planets you would need FTL travel..

Sounds like a monumentally hopeless reality.

> Sounds like a monumentally hopeless reality.

In terms of darkness and hopelessness, this is getting close to Cixin Liu's The Three-Body Problem trilogy.

A rot13 spoiler follows.

V xabj V fgvyy unir cnatf bs rkvfgragvny qernq nsgre gur frpbaq be guveq obbx vagebqhprq gur pbaprcg bs qvzrafvbany erqhpgvba jrncbaf. Onfvpnyyl, n fhcrejrncba gung fgnegf n furrg bs 2Q fcnpr rkcnaqvat ng yvtug fcrrq, juvpu erqhprf rirelguvat vg gbhpurf, vapyhqvat fcnpr vgfrys, gb 2Q. Vg'f bar bs znal JZQf ninvynoyr gb cbjreshy fcrpvrf. Abj gur qnex guvat vf, vg pna'g or fgbccrq. Bapr hayrnfurq, vg'yy xrrc rkcnaqvat ng yvtugfcrrq, qr-qvzrafvbavat fcnpr sberire. Ohg fcrrq bs yvtug vf fb fybj, gung lbh pna qebc vg ng lbhe rarzl'f ubzr flfgrz naq abg pner nobhg vg sbe zvyyravnf.

Nsgre gung, sbyybjf gur dhrfgvba. Unir lbh rire jbaqrerq jul jr yvir va 3Q fcnpr naq abg, fnl, 12Q? Gung'f jul.

Decoding it to ROT18 makes some amusing changes to the numbers.

I think I have kinda grown out of such existential dread, once I started having a sort of intuition that the Universe is too inconceivably large to be uniformly altered, let alone "damaged", by any single event or entity (which also makes me cringe at sci-fi which throws the word "universe" around so lightly.)

More importantly, I started thinking of the "backdrop" of Reality itself to not be Nothingness, but Everythingness.

That is, the blackness we see out there, must not be the default state. I imagine a flood of "white" behind the void, and the reality we perceive is just a heavily-filtered slice of it.

What led me to this way of looking at things was a comment on HN or Reddit, that talked about how, in certain axioms of mathematics, you can have a null/empty set but it's impossible to have a set which contains everything including itself. Whereas in another group of rules, it's impossible to have an empty set because everything else is arrived at by "subtracting" from the "infinite" set!

Maybe someone here knows better of what I'm referring to.

Nice use of rot13.

Why thank you. It's common elsewhere in places that don't have rich comment markup supporting spoiler tags; it dawned on me recently that I didn't see it used much on HN for some reason.

And don't think for a minute that the first human company that gets that tech wouldn't do the exact same thing.

Wilbur and Orville Wright did precisely that for flight until the US govt dismissed the patents due to WWI. The patents, and their insane lawsuits, were poisoning the whole US on flight. Europe grew by leaps and bounds, and had all sorts of aircraft.

This story is oft-repeated here but this paper provides convincing historical industrial evidence that it's a myth: https://papers.ssrn.com/sol3/papers.cfm?abstract_id=2355673

Sounds like the Spacing Guild from Dune.

>Sounds like a monumentally hopeless reality.

Well... actual reality doesn't even old much hope for FTL.

hah but at least, we seem to have the luxury of exploring our neighborhood at our own pace, in any direction, without capitulating to alien overlords.

>I once had, and never used, an idea that the consequence of using such technology was to accelerate dark energy, so that the more civilizations used FTL travel, the greater the energy requirements became. As if seafarers had to deal with the oceans expanding just a bit every time they were crossed.

I believe one of the aborted ending ideas (and dangling plot-threads) for the Mass Effect series was something like this.

Like use of "Element Zero" (the exotic matter unobtanium that powers everything, including FTL travel) releases some kind of "dark energy" that is bad for vaguely defined reasons; one of which being that it destabilizes stellar fusion and makes stars go nova prematurely.

So the "Reapers," or big-bads of the series, were an ancient civilization that set up a recurrent process of culling nascent advanced civilizations to prevent them from growing and using such technology to problematic levels.

They ultimately scrapped it and went with an "AI and Man can't coexist" angle instead.

Star Control II, one of the inspirations for Mass Effect, also had some very interesting cosmic-scale intrigue, between many different species interacting over eons.

https://en.wikipedia.org/wiki/Star_Control_II

You might enjoy John Scalzi's latest, The Collapsing Empire. Not quite the same, but it does feature fast "currents" in spacetime that are in the process of "drying up," leaving distant systems stranded by uncrossable gulfs.

I've read a scifi story with this exact plot, so it looks like you're not alone!

Yeah, it's driving me crazy that I can't remember the author or title. As I recall there are some older species desperately trying to keep younger worlds from using the technology because the problem is going to keep getting worse.

I want to say it's a Ted Chiang story, but I'm not sure why - probably because his is the last collection of short stories I recall reading - but none of the titles listed look familiar.

I don’t think so; as far as I know, I’ve only read his story that was adapted for Arrival.

Well, there was that time Earth was demolished to make room for a bypass. I'm not sure I recall all the details but I think the universe ended as a convoluted consequence?

Yep, that is exactly what I was thinking about. :)

In Accelerando, there was a similar plot device. The anisotropies in the CMB (or maybe just minor aberrations) were caused by waste heat from Type IV/V civilizations running gigantic computations (trying to probe/find vulns in the laws of physics, if I remember correctly).

I thought that was a cool idea: that something as studied, ubiquitous and generally accepted as a natural phenomenon as the CMB is just a landfill, we just don't know what we're looking at.

There’s some Star Trek episodes that touch on this, maybe in later TNG or DS9. Can’t recall exactly at present.

Edit: here we go: http://memory-alpha.wikia.com/wiki/Speed_limit

I missed your comment and made a similar comment without the attached episode. Thank you and the below comment on how they solved it. I assumed they just didn't care as it was the delta quadrant and the whole show is an emergency.

Preventing this damage without a speed limit was the function of Voyager's moving warp nacelles. I think they solved it without moving parts in later designs.

The Defiant class's warp nacelles are angled slightly toward the bow of the ship, at least in some parts of the canon. Some speculate this is for the same reason - a fixed-nacelle design that prevents this damage without a speed limit.

Tangential - comparison of warp coils in different Starfleet ships: https://www.youtube.com/watch?v=gXAoIGTQEBY

> Imagine the "pollution" caused by civilizations [...] Destabilizing solar systems or even entire galaxies, maybe even violating causality..

If you are interested in such a plotline you should read the "The Three-Body Problem" triology by Liu Cixin.

Without going to much into detail: This topic pops up several times in the third (and perhaps already in the second) book of the series.

One estimate of the total exotic matter required to form a bubble puts it around 10^20 galaxies worth.

https://arxiv.org/pdf/gr-qc/9702026.pdf

Those insignificant civilizations don't need to worry about pollution, they need to worry about being gobbled up for mass-energy.

According to Wikipedia:

“In 2012, physicist Harold White and collaborators announced that modifying the geometry of exotic matter could reduce the mass–energy requirements for a macroscopic space ship from the equivalent of the planet Jupiter to that of the Voyager 1 spacecraft (~700 kg) or less, and stated their intent to perform small-scale experiments in constructing warp fields. White proposed changing the shape of the warp bubble from a sphere to a torus. Furthermore, if the intensity of the space warp can be oscillated over time, the energy required is reduced even more.”

If someone violates causality, who should be held responsible?

You.

Despite the sword and sorcery veneer this is actually the premise of several of CJ Cherryh's works, for example : https://en.wikipedia.org/wiki/Exile's_Gate

Ha! Star Trek: TNG actually had an episode about that.

[0] http://memory-alpha.wikia.com/wiki/Force_of_Nature_%28episod...

There's a plot point in one of the sequels to The Three Body Problem like this. Certain spacetime-warping propulsion technologies turn out to leave behind a large mark in spacetime which isn't directly harmful, but is easily detectable even at stellar distances. Because of the Dark Forest theory, such a mark is taken as a giveaway of a careless and technologically dangerous civilization, which causes other advanced civilizations to immediately try to kill the civilization that made the mark before it can advance further or launch its own attacks.

Take it up a level: maybe the entire universe is the result of this. The Big Bang was the result of flushing another universe’s waste processes.

Of course, there is a Star Trek episode (TNG) where some alien scientists discover this, but nobody wants to believe them including the Enterprise as the consequence is greatly restricted warp drive (warp 9 becomes only emergency). I think they mention it again once or twice. Maybe a super fan can attach the episode #.

Season 7 episode 9 (Force of Nature). I believe in Voyager they mentioned something about a new warp engine design that mitigated the problem.

I recall a bit of scifi, the title escapes me, where they placed an opaque cloud between our galaxy and Andromeda, to block any form of communication, so they could have FTL without violating causality.

What you describe is a teeny-tiny bit of a a spoiler. Erring on the side of cation, obfuscating my reply.

The book you're talking about was by Alastair Reynolds. It's the third book in the "Other" section here: https://en.wikipedia.org/wiki/Alastair_Reynolds#Novels.

My brother has (I think jokingly) suggested that the dark energy expansion of the universe is an indication of such pollution.

That sounds like some great sci fi, actually.

Ever since I played the awesome old RPG called Planet's Edge [0] and the better-known Star Control II, I've been taken to muse about cosmic coincidences.

Popular sci-fi like Star Wars or Star Trek etc. don't really touch on those possibilities in a convincing way.

As in, very few fiction truly conveys the ..indifference.. of the universe, and all the actors in it going about their own businesses and interacting only incidentally, even if to monumental consequences to each other, but without a lot of conscious intent or an overarching plan.

Kind of like how most of Earth's history has played out, even if it may all seem interconnected and purposeful due to the much more relatable scales involved.

[0] https://en.wikipedia.org/wiki/Planet%27s_Edge

> indifference.. of the universe, and all the actors in it going about their own businesses and interacting only incidentally

That was pretty much the point of Rendezvous with Rama, until the sequels ruined it.

If you can engineer spacetime, there really isn't such a thing as a long-term consequence anymore.

Not even to those who can't engineer spacetime yet?

So the ant in the universe where shoes have just been invented and people stop hesitating to step on them?

The scale between ant and human is large, but probably still smaller than the ratio power-wise between the civilizations with and without exotic matter. Might as well just call one gods and the other mortals.

That's right. The engineers have eternity to achieve outcomes satisfying to all parties. And if they choose not to, well, that's an all-time consequence, not a long-term one.