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?