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In most Space operas, space wars involve battleships, fighters, energy shields, missiles , bombs and lasers (and sound in the vacuum of space).

This largely mimics how planes and mother ships were used during WWII.

This of course is needed for some impressive battles but in reality if we reach that level of technology, I think that anything other than lasers would be useless. No missiles, no fighters, no railgun, no bombers. I want to describe a space battle that is realistic in a world were powerful lasers are a reality.

What kind of tactics would be used?

In theory a laser has infinite range but in practice, it is not a straight line but a cone of light. After a certain distance, the cone is so wide that the laser is not damaging anything. So lasers have a range.

Lasers are also blocked by solid objects like asteroids, moons and planets.

Given those parameters, it looks like space war would be a very boring but highly strategic game of placement, trying to stay out of range of your enemy’s laser, hiding behind asteroids, moons and planets.

Most importantly, HAVING THE BIGGEST GUN is a huge advantage. By that I mean that if your laser has an effective range of 5 light minute, and your opponent only has a laser that can shoot at 4 light minute, he can almost never harm you and you can easily defeat his entire army.

This is very similar to how pre airplane naval warfare operated. Ships had canons and trying to not be in range of your opponent was the most important thing. Weather and sea conditions added some randomness that is not even present in quiet emptiness of space.

Of course AI would be way more efficient than humans so space ships would be crewless. They would basically just be lasers with some energy source floating in space.

Can you see any use for fighters and projectile in this context? I don’t see any but may some of you can come up with interesting use cases to spice up this realistic but boring way of fighting in space.

Fighters, missiles,bombs, railguns are obsolete?

Projectile based weapon in space have the following disadvantage:

-they create recoil when you use them which could be significant for rail guns for example. Laser also create a recoil because photons have momentum of E/c but that is orders of magnitude less

-projectiles have a limited number of use, once you run out of missile or rail gun pellets, you are screwed. Restocking in space is inconvenient and expensive

-projectiles are relatively slow in the context of space war where targets can be easily hundred of thousands of miles apart and can therefore easily avoided

-they can also easily be deflected/destroyed by any laser weapon

-they would certainly be less effective than a sustained laser beam concentrated on a small area to pierce energy shields Laser on the other hand offer all those advantages:

-they are quasi unlimited in number of times you can use them (you are still limited by the amount of energy you can generate) but since you are just converting energy to light, this is way more efficient than carrying missiles or throwing kinetic energy at your target.

-they move at the speed of light so impossible to avoid them, by the time your sensors see them, you have been hit.

-they can focus an enormous amount of energy on a small surface and therefore have more piercing power

Close combat as is pictured in most space opera also makes no sense if you have a weapon that travels at the speed of light.

If you are within a few light seconds (within 500,000 miles) of each other then you can consider that you are in close combat. Having a small fighter even travelling at 10,000 miles per hours is quite useless. Also forget about having a human piloting it, the amount of Gs it would be subject to would turn Han solo into meat pie.

I see no reason for small fighters to exist. Can you still see any use for fighters and projectile in this context?

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closed as too broad by L.Dutch Jan 9 at 6:55

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

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    $\begingroup$ I have to say that I don't agree with most of your assumptions. Lasers might not need ammunition, but they need massive energy reserves which still need to be replenished (probably a recharging capacitor), and good rail gun projectiles can't be shot down because they would travel too fast for most computers to react, especially in close. Also, your concept of fighters ignores the use of drones as mobile weapon platforms, bypassing the G force issues on pilots. I may put this together in a framing challenge answer later but for now I'd argue that the question relies on incorrect assumptions. $\endgroup$ – Tim B II Jan 9 at 6:19
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    $\begingroup$ (I should point out that the above is not a criticism as such; I'm genuinely interested in where these assumptions come from and whether or not you might want to add some additional framing to justify them.) $\endgroup$ – Tim B II Jan 9 at 6:22
  • $\begingroup$ Please narrow down your question to a single problem. It is fine to spread it over more, related questions. $\endgroup$ – L.Dutch Jan 9 at 6:56
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    $\begingroup$ One side note: at a distance of 1 light second a laser is already spread over a circle with radius of tens of km (see lunar ranging experiment) $\endgroup$ – L.Dutch Jan 9 at 6:57
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    $\begingroup$ Besides, if everybody would use lasers, why wouldn't you expect it to be countered with (reflective) armor or maybe using something that creates dust clouds to mitigate the damage? If they'd continually improve both laser weaponry and defence against it, the first one to use kinetic based weaponry would gain a huge advantage. This may create a cycle where a wide range of variety of weapons may come to use. Also why do you assume that while technology progresses lasers would improve while other weapons would stagnate? Arms races were always a significant part of warfare. $\endgroup$ – Battle Jan 9 at 7:11
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Yes. Very much so.

In the following answer I’m assuming that your lasers and power source are handwaved to be viable weapons in the first place, and so can be trusted to cause some damage if they score a hit.

First let me address fighters.

Your lasers will still take time to get to the target, even if they can’t see them coming. This means all they have to do to avoid the lasers is to change trajectory randomly and your lasers won’t be able to hit them at light-seconds distant. This will be true until they get quite close. Your slower battleship, on the other hand, will be a hittable target for the fighters at a larger distance as it represents a larger target and a slower one. The fighters can kink back and forth just outside of your battleships’ effective range but just inside their own. A battleship without some manoeuvrable fighters if it’s own will be unable to counter this threat.

Secondly: projectiles.

Basically this comes down to a question of what kind of damage you want to do. Lasers might deliver a thermal load, but with ceramics, mirrors, ablative armour or good refrigeration systems a battleship can mitigate that. It’s hard to deal with being hit by lumps of tungsten moving at several kilometres a second, especially if your armour is designed to protect against lasers.

The problem with projectiles (as you noted) is that they can be easily dodged and ignored. But what if they couldn’t?

Cue missiles. Well, drones really. Or mines, depending on how you design them. Anything with post-firing aim-and-murder capability becomes a superweapon in a world of just lasers. Thought that projectile was going to miss you? No, wait, now it’s close enough you can’t dodge it’s rammed up it’s engines, corrected course and is going to hit you amidships even if your lasers reduce it to a molten cloud of particulate matter. Do you now use your lasers to ‘destroy’ every potentially threatening solid projectile or to aim at the battleship that launched them? Remember: anything you aren’t sure is completely dead (even ‘wreckage’) can be weaponised, and even things you are sure are dead exclude you from maneouvering or aiming into certain areas.

If you combine both points then you can have unmanned drones be both your fighters and your missiles. Launch them from the main ship, engage in jinking and laser firing while accelerating like a madman towards the enemy. If one drone gets destroyed then use it’s wreckage as moving cover to get you close enough to the enemy ship, then close the distance. Even one good strike will create exploitable blind spots in the enemy field of fire, and once you have that you can park all remaining drones in the blind spot and lase until your enemy melts.

But!!! Those are simply some reasons I can see that fighters and projectiles might still be useful. I’ve built a world that centres around drones as the primary mode of combat though (part of a board game that never really worked). If you have decided that the military doctrine of your world is “Big battleship, Big Laser” then you can ignore them. The future of combat in space is so very up-in-the-air (hah) that you can make pretty much any scenario seem plausible.

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