Imagine There Is An Alien Interstellar War But There Is No Faster-Than-Light Technology. How Would The War Play Out?

“Your biggest enemy in intergalactic war is not your enemy, that is reserved for Time” ~ The Angry UFOlogist

In the vast reaches of the great unknown probability dictates that there will be far more civilization on the low end of the technological spectrum than on the advanced end. Let’s imagine that war is not a unique concept to just our dirty ball of rock and dirt. Somewhere out in the vast blackness, there is a war raging between two adversary’s who have not achieved faster-than-light (FTL) travel technology.

For this bit of imagination, you must forget all you have seen in movies and TV in regards to how Aliens may come to the breach. There will not be phasers, photon torpedos or even very much ship-to-ship combat. Those are the plot devices created by movies and TV. You must forget all that because REAL interstellar war at relativistic speeds is a totally different kind of monster. One that is not explored in TV and Movies to any great extent.

Now I can not readily imagine a situation where war would break out between two planets that are light years apart. But let’s assume that more advanced intelligence’s will find a reason.

Could first contact gone like this.. It would be a war of radio signal based insults. And because the signals would take years to travel.

Alien (A) – “Your great grandma was the size of Saturn rings.”

2 generations later…

Alien (B) – “I will strangle you in my mind for years to come.”

2 generations later…

Alien (A) – “Go sit on a plasma jet”

You get the idea of true futility in all this. The reason does not matter for our purposes, what I wish to explore is the HOW.

I will assume that this is a war of species annihilation, with no possibility of peace. This calls for absolute ruthlessness.

So let’s set some parameters for war.

  1. These are not the only two alien races in the galaxy.
  2. No FTL, but both possess the ability to go slightly below light speed.
  3. More advanced tech than Earth.
  4. Both sides have roughly the same technological prowess.

6a00d8341bf7f753ef017ee4364e2c970d-600wiLet’s say there is a group of aliens in the Alpha Centauri system and a group of aliens in the Sirius system and they want to duke it out in an all-out war. Since Alpha Centauri is 4.23 light years from here and Sirius is 8.61 lightyears, let’s estimate their distance at 4.38 lightyears.

Without FTL technology, the logistics of resupply an invasion force would be daunting even for the most advanced civilization. This means that in any conflict involving an invasion of one race’s home star system, the defender would have a HUGE advantage.

An advantage probably sufficient to overcome even a significant gap in technology. Given similar levels of technology, the defender should almost always win.

Thus few rationally self-interested races would ever launch such an invasion. Even in the off chance of success, the lack of FTL travel or communications means the home civilization will have little political control over the invasion forces that they send, who will essentially be independent agents from the moment they are launched.

Nowadays, most soldiers don’t need to return home to their crops and are able to stay in the military for a few years. Still, when it may take 4+ years to fight one battle, not all soldiers will want to reenlist after spending so long in a spaceship, and the public probably wouldn’t tolerate having their loved ones away for decades. Also, since this type of warfare will probably take place when civilizations are new to space exploration, planets will find it far too expensive to keep ships out for too long.

So large scale invasions with huge space fleets and set-piece battles in the void are probably out, except in rare cases where one the attacking side is irrationally suicidal. And races with a tendency towards irrationally pursuing suicidal actions are unlikely to survive for long.

Perhaps aliens advanced enough for contacting each other in a timely way would also be advanced enough to agree to simply share a complete computer data dump which inventoried their resources and strategies for war.

With this, a third party computer would analyze the data and determine if there was a war, who would win. Also, what would remain of their respective resources. With this information, the two adversaries would agree on the basis for a peace treaty.

But we’re not here for peace. Cry ‘Havoc!’, and let slip the dogs of war.

Scenario 1: Both civilizations have capabilities that allow them to go to 0.99c, where c = speed of light

It would be a very boring war for the first five years. Both fleets would go at 99% the speed of light and their fleets would arrive in about five years-ish. If they have the exact same weapons, then both fleets would wipe the other one out. If they don’t, the one with better effectiveness against the other fleet would win the battle. This could be achieved by trickery, by strategy, or by better quality.

A little bit of trickery history is in order here…

Zhang_Fei_-_RTKXIIThis is Zhang Fei, a prominent man and a great warrior during the devastating Three Kingdoms War in China. During a battle against enemy warlord Cao Cao, Zhang Fei brought twenty soldiers with him and had to defend a bridge against Cao Cao’s much larger army. Thus, he told his men to tie branches to their horses and ride around, dragging the branches around. This threw up a lot of dust. When Cao Cao and his Generals and troops arrived, they saw only Zhang Fei standing on the bridge, huge weapon ready.

Zhang Fei was a large and very intimidating person and thus made Cao Cao’s troops wary of him, then they saw the dust clouds and concluded that there must be an ambush with horses should they cross the bridge. Not only that, Liu Bei, the warlord who was Zhang Fei’s brother, had hired Zhuge Liang, a brilliant tactician that had not too long ago, dealt a devastating blow to Cao Cao’s army. Fearing they may fall into an ambush, the warlord hesitated. Zhang Fei then yelled in a booming voice “I am Zhang Fei of Yan. Who dares fight with me?” This shook Cao Cao’s troops and he retreated.

This shows just how effective deceptions and trickery are in wars. These two alien races are equally matched, but that doesn’t mean that Planet A can’t fool B into thinking they are so much more advanced and force an armistice or they will be destroyed. How? Planet A can fake communications and weapons. They can use holographic technology to simulate artificial gamma-ray bursts.

But it gets even more strange and convoluted.

In this scenario, your enemy is not your biggest enemy… That is reserved for Time.

These two combatants spacecraft will follow the laws of physics as we know them. The two interesting issues that they will have to deal with is time dilation, 1) the increasingly social isolation between soldiers and society as they ship out, fight a battle in some distant star system, and then return and 2) the technological change.

time_dilationBased on time dilation, to the soldiers, they have been engaged for several years, but at 99%c for nearly 5 years centuries would have passed on earth and your enemies planet. From a societal point of view, it is like taking a World War 1 soldier and putting them in a war in the 25th century. Your enemy would have centuries of time to advance their weaponry and tactics. You would essentially arrive the same as when you left space dock while your enemy might have time to advance a notch on the Kardashev scale. After the most epic ass kicking every recorded if any of your warriors survived they would be relics of a bygone age. After the battle, everyone they knew would be dead and they would have little connection to the society they are defending. Sometimes the battle is over almost before it begins based upon this uncertainty.

Scenario 2: Aliens have tech comparable to fastest manned spacecraft we have ever built

The fastest manned spacecraft we built was Apollo 10.

apollo10Apollo 10 was the final dress rehearsal of the landing of the Moon, and it clocked at a maximum speed of about 40,200 km/h. Making all the calculations gives us that if the two alien fleets go off from the Alpha Centauri and Sirius systems at the same time, they would meet in 358-ish years. Then the same thing would happen again, but a bit longer since the two now have more primitive technology, and then the two would go home. But this means another more boring war. Yawn!

This war would be mostly boredom, punctuated by the occasional apocalypse.

Scenario 3: Aliens do not have FTL but have advanced science and a whole new bag of tricks.


The idea behind them is to launch the smartest hyper-intelligent A.I. you can produce in the smallest package you can build that allows for rapid self-replication. The lightweight allows it to be launched at near light speeds without producing a thermal bloom that you could see on the other side of the galaxy and more importantly allows it to slow down without being noticed while seeding the target system with replicators.

Entire armadas can be quickly built and fueled and can proceed to attack from all vectors nearly simultaneously. Fleets can be anything from biological spaceships to massive hives of nanobots to good old fashion battleships in space!

main-qimg-507b74dc55bd7415b66990950884b5e8-cI imagine a pineapple-sized object the quickly and quietly builds quintillions of reflector panels that network via lasers coms. When the swarm hits a critical size it drops into a lower stellar orbit where it can start reflecting nearly the entire output of the host star on its targets.

(That’s no moon. it’s a star whose entire stellar output is being collimated by a phased array of solar reflectors. )

A weapon swarm like this would yield biblical levels of power, 350ish yottajoules per second for a star like our sun. So what could you do with 350 yottajoules/ sec? (a septillion joules. 1 Yottajoule is equal to 1024 joules. 1 YJ = 1 000 000 000 000 000 000 000 000 J.)

Well, you could lift the crust off of Earth and covert what was left into an incandescent light bulb of white plasma. You could ignite Jupiter and turn the solar system into a temporary binary star system. You could launch Pluto at a neighboring star system at about half the speed of light (and finally settle the Pluto planet debate)

You could focus the output of a Star on a planet in another star system. This will probably be the mutually assured destruction weapon of the future. An Autowar along these lines could be sent to an uninhabited system (or even inhabited if you’re a jerk like that) where it could proceed to convert everything from the Oort cloud to asteroids into reflectors. The reflectors could be dispersed and angled in such a way as to make detecting them difficult. Once enough were made they could be used to attack other star systems or deconstruct the local planets to make even more reflectors.

Let’s consider Relativistic Missiles.

1314093230313If this is a war of annihilation, the best bet may be to put all resources into un-piloted relativistic warheads. Just rocks with final approach guidance. It makes a difference here whether the orbital details of the enemy world are known. Endpoint guidance is very difficult for a relativistic projectile – deflection represents a huge amount of energy. It may be necessary to fragment the projectile at some point well in advance of the impact. This would achieve a “shotgun” effect.

Aiming what amounts to a grid of relativistic gravel should ensure some hits. If the weapon is properly designed, this should be enough. Even better would be a salvo of such devices, arriving across the course of a planetary day. This will ensure complete devastation of the planet. A barrage of unmanned space-craft, accelerated to relativistic speeds, to target the victim system by the impact force, would be monumentally damaging even to very advanced civilizations and incredibly hard to defend against. It would cost a lot more to stop such an assault that it would to launch one, and require a level of technology significantly higher to accomplish it. Meaning a technologically weaker race can defeat and destroy a technologically more advanced race, so long as they get the first shot in. Wars in such a scenario would take thousands of years of preparation but be over in seconds, and the outcome decided thousands of years in advance. Given adversaries of similar capabilities, whoever detects the other first and launches first, wins.

Except there are two problems here.

First, the universe is a big place. What if someone else is out there, a third party, watching? Suppose they detect the launch and/or aftermath of the relativistic missile barrage. What are they to think of a race with such a penchant to commit genocide, and how would they respond? Knowing that they themselves could easily be the next target, their only rational course is to immediately launch their own relativistic assault on the aggressor race to take them out as soon as possible.

Second, what if the victim race detects the attack before it arrives? Since the missiles cannot go faster than lightspeed, there is a window where the victim can see them coming. Since it is easier to launch such an attack than it is to stop one, even if the victim race cannot save itself from the incoming attack, it may be able to launch a retaliation strike before being hit.

And so we have Mutually Assured Destruction again.

And so no rationally self-interested race is likely to choose to start hostilities in this manner. It would be basically like turning on a neon sign for every nearby civilization to see saying “I AM A GENOCIDAL MANIAC, YOU’D BETTER WIPE ME OUT BEFORE I KILL YOU”.

Thus, once more, being the aggressor in an interstellar war is suicide.

To destroy one’s own homeworld at the beginning of the war recalls the Helvetii invasion of Gaul, as described by Julius Caesar. The Helvetii burned their villages before departing, to enforce commitment to armed mass migration.

This would all be played out over the course of centuries. For each species, there would be nothing but the War, for as long as they can remember. Once all is resolved, it seems very possible the species will remain warlike. With the next species, they may not wait for a war to be declared. Fortunately, the war scenario is bizarre. We might meet an insanely paranoid and violent species out in the galaxy; that is the basis for several genres of fiction. I’d like to suppose that intelligence eventually gets to reason and some species-specific version of enlightenment.

We know about only one space-faring species – humans. We can be violent and paranoid and insane. Look what I just wrote! But I was just having fun. We humans have our good points. We are not so bad.

We wouldn’t just go out and mug another species would we? We’d send diplomats….then mug them.

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