Implications of no limits FTL

[Sky Captain]

In some sci fi settings FTL travel is not really limited, you can open a hyperspace portal, jump point, wormhole whatever and exit into low orbit or even inside atmosphere with seemingly no restrictions. I think it happened on screen sometimes in Stargate, Babylon 5, Battlestar Galactica and Star Trek.

It seems that this capability have very serious military implications that writers don't realize or choose to ignore. In a universe with several hostile factions and FTL that allows to jump anywhere a massive surprise strike is just so easy. Defender has to be strong everywhere while attacker has to be strong only at one place. Think of a huge fleet capable of wiping out any local defense forces appearing with no warning potentially in any star system.
Extremely destructive terrorist tactics are easy. Take a huge freighter load it with rocks and accelerate in deep interstellar space where no one would notice as close to c as sublight propulsion allows. Open a jump point leading into atmosphere of a target planet. You have unstoppable planet killer using off the shelf widely available hardware. Jump capable missiles with huge fusion or antimatter warheads could do the same.

Would such setting remain stable or total destruction ensues. Would something like MAD in real world work to keep peace between factions. If you destroy my worlds I destroy yours with weapons hidden somewhere in interstellar space? What about non state actors if every FTL capable freighter is also a weapon of mass destruction?

[Solauren]

Planetary shields that also block hyperspace travel.

Cross on, you collide with it.

Problem solved.

[Batman]

The in-atmosphere jump in B5 was considered super-risky and required a ground controller feeding them exact coordinates. While Trek does routinely Warp out of orbit their sublight acceleration is up for grabs and may well involve mass reduction. From Stargate again I remember one time they used hyperdrive in atmosphere and that was a fighter doing it in a 'who cares where it gets out as long as it's far away' situation. I think you need more than a single 'done once in a dire emergency' to establish a pattern that would make this a viable tactic.

[Tribble]

Star Trek may not be a very good example here because regular warp drives are relatively slow by FTL standards and there are FTL sensors around that can detect them. That's not say to say sensors are full proof and surprise attacks do happen, but they seem to be the exception rather than the norm. Usually vessels / fleets are detected far enough in advance for at least some ships in the area to be able to intercept them.

[Sky Captain]

Planetary shields that also block hyperspace travel.

Cross on, you collide with it.

Problem solved.

Not every sci fi setting have planetary shields or shields in general, It would require shield to be active all the time. If there are some sort of sensors capable of detecting incoming FTL ships then it mat work. Jump drives that are essentially instant teleportation would give no warning. Planetary shields in sci fi settings that have them often are very expensive installations limiting their use only to most important worlds.

The in-atmosphere jump in B5 was considered super-risky and required a ground controller feeding them exact coordinates.

If the thing coming out of jump portal is planet killing WMD then minor accuracy issues won't matter. In case of relativistic kill vehicle as long as it comes out in general vicinity of a planet and is aimed at it it is a win. Jump calculations without assistance generally were accurate enough to arrive within few hundred km of a target.

From Stargate again I remember one time they used hyperdrive in atmosphere and that was a fighter doing it in a 'who cares where it gets out as long as it's far away' situation. I think you need more than a single 'done once in a dire emergency' to establish a pattern that would make this a viable tactic.

IIRC they did it more than once. During Anubis attack on Earth SG 1 flying small Goauld freighter came out of hyperspace in atmosphere over Antarctica close to Ancient outpost. That is damn good accuracy especially considering it was done by standard freighter likely not having bleeding edge military grade navicomputer. Yeah, they nearly crashed doing it, but if you send a WMD it doesn't really matter. If Anubis had used similar maneuver to send a freighter loaded with multi teraton Naquadriah bomb to explode over US it would be game over for Earth.

In diferent episode SG1 used similar freighter to take naquadah asteroid into hyperspace to bypass Earth. If Goauld who deployed that asteroid had released it from hyperspace just over the Earth it would be game over.

[Solauren]

IIRC the hyperspace jumping the asteroid required all their ships power and burned out the drive, and was risky as hell.

[Bedlam]

The main problem is that as long as the chance of making it through is less than millions to one there probably isn't any reason not to send through a horde of drone ships. If the odds of missing are 99.9% then some will still hit, if they have the same probability of exploding then again you've still succeeded and you've not really lost all that much.

[Solauren]

Actually, wouldn't that depend on

How much it costs to launch all enough drones to insure the enemies destruction under that method

vs

How much it costs to launch a conventional attack to cause the same effect?

[Sky Captain]

IIRC the hyperspace jumping the asteroid required all their ships power and burned out the drive, and was risky as hell.

It was because freighter had inadequate hyperdrive for object that massive. If you prepared similar asteroid weapon you would use hyperdrive that is up to a task like one from a Hatak.

The main problem is that as long as the chance of making it through is less than millions to one there probably isn't any reason not to send through a horde of drone ships. If the odds of missing are 99.9% then some will still hit, if they have the same probability of exploding then again you've still succeeded and you've not really lost all that much.

Yeah, that is the problem. In Stargate universe multi teraton bombs are a thing. Such bomb exploding in low orbit would set fire on the surface to everything within line of sight. Coming out of hyperspace at low orbit altitude is done routinely with no issues. A drone ship with bomb would have very good odds of making it. I would say better than 50 %. Send a few dozen and you have ignited global firestorm on a planet without risking anything valuable.

[Eternal_Freedom]

While that is prefectly true, the reason we don't see that done in SG-1 or SG:A is that the enemies they fight aren't out to just obliterate everything. The Goa'uld want to conquer and enslave us, the Wraith want to feed on us. All things that are difficult to do if we're all on fire.

The reason Anubis used the asteroid on a natural trajectory was he wanted a way to wipe out Earth and the SGC without making it look like a direct attack and invoking the wrath of the Asgard via the Protected Planets Treaty.

All manner of horrible ways to wipe out civilisations are possible in all manner of settings, but it's very rare to have an enemy that actually wants that. Eve if they don't care about the humans and just want the resources, again, blasting/incinerating/irradiating a huge chunk of the surface interferes with that, so they look for other ways.

[Elheru Aran]

If your universe has enough high tech that planets are mostly just useful as a source of raw materials (think Culture level)...

You still want to preserve them, mostly because rendering them uninhabitable is going to make it all that much more of a hassle to exploit the planet. If you're some kind of Venusian lava-species that breathes toxic gases and finds volcano heat very comfortable, then that might be one thing, but there aren't likely to be very many species in that kind of situation.

It pretty much comes down to real estate being a very safe investment in pretty much every universe...

[Batman]

Depends seriously on your tech level. Inhabitable planets means free gravity, atmosphere, and biosphere. If you're at or past the point where you can easily provide those artificially on the scale required then yes, planets are mostly useful for their mineral resources and rendering them uninhabitable or even breaking them up entirely may very well ease extracting those.

[Sea Skimmer]

Extremely destructive terrorist tactics are easy. Take a huge freighter load it with rocks and accelerate in deep interstellar space where no one would notice as close to c as sublight propulsion allows. Open a jump point leading into atmosphere of a target planet. You have unstoppable planet killer using off the shelf widely available hardware.

People would probably mitigate against that risk by placing all merchant ships in some form of organized government service or equipping them with Marine guards. Sure terrorists in Pakistan did try to takeover a warship that one time, but they also got as far as the gangplank.

Would such setting remain stable or total destruction ensues. Would something like MAD in real world work to keep peace between factions. If you destroy my worlds I destroy yours with weapons hidden somewhere in interstellar space?

That would tend to be the jist of it between nation states. Also if you want to be REALISTIC about it, then the resources of space with instant FTL travel would be so lol vast that it's hard to see what reason we would ever have for warfare, and that any rouge faction in the intergalatic order of nations would be looked upon EXTREMELY poorly by everyone else, whom could after all instantly gang up upon them.

Remember if we aren't using author fiat, and instant or near instant unlimited FTL.... the real universe has around 1 septillion estimated planets. Even if only 1 in a trillion is habitable that would still leave a trillion total fit for human like settlement! How many civilizations are we expecting to exist becomes rather relevant. Plus space habitats, terraforming ect.... become more and more appealing the more advanced and high resources a setting gets.

What about non state actors if every FTL capable freighter is also a weapon of mass destruction?

Domestic terrorism would certainly be a concern, people will still have grief against their own government for certain. But then if that's such a clear and present danger then why let non state actors buy large ships? Nowhere on earth I'm aware of allows civilians to own weapon capable aircraft for example, and while buying something dangerous like an LPG tanker or small nuclear reactor is plausible you have to jump through a lot of regulatory hoops to do it. Of course full scale rebellions are the exception to this rule, but a rebellion that starts using planet killing WMDs is pretty self defeating.

Where you would get a real problem is if the FTL tech it's self doesn't have to scale up, a small star drive for a yatch can also move a tanker or a whole space base FTL with equal ease. But then that's just an argument for not allowing random people to own such things.

[Sky Captain]

Those are good points. I guess limiting access to FTL tech to only government organizations really depends on how difficult/exprnsive the drive is. If it is something that can be bult by group of competent moderately rich hobbyists then there is a big problem. If bulding it is comparable to building a nuke in real world then limiting access could work.

All manner of horrible ways to wipe out civilisations are possible in all manner of settings, but it's very rare to have an enemy that actually wants that. Eve if they don't care about the humans and just want the resources, again, blasting/incinerating/irradiating a huge chunk of the surface interferes with that, so they look for other ways.

It works when one side is massively stronger. No need to break out nukes to contain insurgency or similar. If fighting between peer opponents breaks out then if one side starts to loose conventional war there would be huge incentive to use WMD's to solve the problem.