Imagine a science fiction universe where...

  • most races have a large amount of excess energy (i.e., fusion),
  • AGI is very rare (not a consideration),
  • interstellar travel is fairly standard via wormholes (teleportation),
  • and all the typical types of weapons are commonplace: missiles, drones, projectiles, lasers, etc.

What kind of defensive technology could allow ships to be nearly invulnerable? (Ideally affordable and not too far into the realm of mystical sci-fi.)

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    $\begingroup$ Affordable and (nearly) invulnerable? What fun is a universe where everyone has cheap, perfect technology? Good stories are always based on weaknesses and how to circumvent them. What does "nearly invulvernable" mean? Compared to what? The missiles (which you haven't described) or a black hole? Invulnerable to energy (how much? what kind?) or kinetic (how much? what kind?) or both? Are you expecting defenses based on 2020 tech or future tech? Why can't you say your shields are based on the "Johnson Effect" and that makes them "nearly invulnerable?" What are you expecting as an answer? $\endgroup$ – JBH May 12 '20 at 15:37
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    $\begingroup$ Why are there weapons if the ships are invulnerable? What are you shooting if the ships cannot be harmed? $\endgroup$ – Ryan_L May 12 '20 at 16:28
  • $\begingroup$ @Ryan_L Two reasons: (1) They are nearly invulnerable; not completely invulnerable. (2) So that they are too busy to shoot back at you. $\endgroup$ – The Daleks May 12 '20 at 20:13

Instantaneous detection and teleportation

Space is very big. Really big. So if you could dodge any incoming missile, bullet, drone, projectile and even laser, by instantly transporting to an alternate location of your choosing, this would be a good way to be untouchable. All these weapons would quickly become ineffective.

You already have wormhole technology, this could be adapted to suit a defensive system, not just for the purposes of transport.

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    $\begingroup$ Only problem is that lasers move at light speed, and so does information, so would be pretty tough to dodge a surprise laser weapon. $\endgroup$ – LukeN May 12 '20 at 15:44
  • $\begingroup$ @LukeN Then you have your defensive technology: ablative shielding. The spaceships have a coating of ablative ceramic shielding which can defeat laser shots, and resorts to jumping out of danger whenever things get too hot. $\endgroup$ – Rekesoft May 13 '20 at 9:26

A defense is only "nearly invulnerable" until someone finds a way to beat it, and if war's the motivation for a change in offensive paradigm, that doesn't generally take very long.

Any solution we come up with would eventually get exploited and defeated in a real war, so perhaps what we're working with is either something not actually designed for a real war, or something that isn't actually a physical defense. A combination of the below two factors might suit you nicely.

The False War

Most interstellar civilizations learn to make peace with themselves and each other, or they fragment or are overwhelmed by the ones who defend each other when things get serious. The universe might not be governed by an overarching alliance, but it is at peace, since nobody advanced enough to build spacecraft is really in the business of getting anyone upset.

Nonetheless, some species have war on the brain, so they need to vent steam by holding mock battles. The weapons used in these battles are minimal, and the victor is declared based on, say, who depletes their enemy's shields first, or who fought more impressively according to some third-party judges.

Perhaps these battles have real consequences in place of actual space warfare, like territory shifts or financial/resource rewards. Why wouldn't you destroy your opponent outright if you wanted this? Well...

Too Big To Lose

Spacecraft are extremely expensive to the point where only a small number even exist, and they're highly valued across the universe for being so versatile and mobile. Destroying one robs you of an asset that you sorely need more of, so combat, which is only done if you can track down a wormhole-hopping spacecraft (difficult and requires a lot of coordination), involves boarding actions and piracy rather than long-range weapons.


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