Is Science Fiction Losing Its Charm Due to Unrealistic Space Travel?

[DaveC426913]

I see. :)

One more question, what do you think about the Yamato like role of fighters?
Their primary goal was to get close to the enemy to get exact coordinates, and send it to the battleship.
I guess, due to limited sensor accuracy it isn't that easy from far away.

I'd say that falls squarely into the 'plot device' bucket, with a fair bit of gap all around.

 

[GTOM]

Ok, I see, but could you explain a little bit?

You can have big sensor arrays on a battleship, but still they have a limited accuracy, resolution, the enemy will likely jam them.
Maybe you can get better coordinates from close range. Well without FTL communication device, they will be a bit obsolate, when they reach the battleship, but they can be still better, than those you can simply observe far away.
Simple probes can also get coordinates, but they are defenseless, and can't finish off a damaged enemy.

 

[DaveC426913]

Ok, I see, but could you explain a little bit?

You can have big sensor arrays on a battleship, but still they have a limited accuracy, resolution, the enemy will likely jam them.
Maybe you can get better coordinates from close range. Well without FTL communication device, they will be a bit obsolate, when they reach the battleship, but they can be still better, than those you can simply observe far away.
Simple probes can also get coordinates, but they are defenseless, and can't finish off a damaged enemy.

They can make up whatever technological constraints they want to get the story they want. There's no rationale to the technology except that which makes for better plot.

"This big ship is cool but we need fighter combat for awesome action scenes."
"Why? We've got this giant ship that can do everything!"
"Yeah well, we can only have so many shots of the battleship before we need some one-on-one heroics. Hm. Let's say the battleship has short range on its sensors, then they need to send fighters in."
"Sounds kinda lame."
"It is, but you think of a better reason for having dogfights in."
"All right. Poor sensors it is."

 

[Ryan_m_b]

You can have big sensor arrays on a battleship, but still they have a limited accuracy, resolution

The bigger they are, the better they are. Assuming for a moment that we are just talking about something like a telescope (that looks for visual and infrared) if the ship has interferometers along it's length then it is in essence a giant telescope (there's an equation for figuring out the resolution of a telescope based on its diameter but I don't remember it). If the ship needs better resolution then what it should do is spread out a bunch of probes in an ever expanding sphere so that they act like one giant telescope rather than loads of tiny ones.

If we're not just talking about telescopes though IIRC a larger ship benefits from being able to house neutrino detectors which would make any ship using a fission or fusion reactor/drive stand out like a flare in a dark field.

They can make up whatever technological constraints they want to get the story they want. There's no rationale to the technology except that which makes for better plot.

Exactly.

 

[GTOM]

Yes, we became pretty OFF.

Ok, I understand what you say.
I read atomic rockets, pretty much ruining even the books of Heinlein. :((

I guess this Ender is a fine character, but i would still like the read or write about different kind of battles and characters... now i don't see much options to do that without every kind if purely fictional hyperspace based device.
Or leave out entirely the war scenario.

 

[Ryan_m_b]

I would still like the read or write about different kind of battles and characters... now i don't see much options to do that without every kind if purely fictional hyperspace based device.

I would recommend the Dread[/PLAIN] Empire Fall trilogy. It's not very well known and it's a bit soft-SF but it has some of the best and most realistic descriptions of space tactics I know of e.g.

• What kind of evasive manoeuvres ships should do to avoid getting hit whilst staying close enough to offer each other covering fire but not too close so as to take each other out if they are hit (as they use antimatter for propulsion ships go out with a bang when critically struck)
• How to fight over light hours of space
• How to use gravity wells and planets to your advantage
• Techniques for managing the crew under high-g

On top of that there it covers how to lead a resistance in a very centralised (all comms monitored, everyone on a biometric database) and totalitarian regime.

EDIT: Now that I think of it DEF does have a somewhat convincing use for a fighter-type craft. Basically when they are fighting over long distances (light minutes-hours) they send out small one man ships called pinnaces along with a swarm of missiles. The job of the pinnace pilot is to give last minute tactical orders to the missiles depending on the situation at the time.

 

[PrepperMike]

read Ian Douglas.

 

[GTOM]

In other threads, we had a consensus, that fighters and corvettes are "brown water navy", operating on orbit, and big shafts of moons and asteroids.

Otherwise, I 've also thought about beam empowered fighters and small missile control ships.

I see that trilogy ruled out AIs.

 

[PrepperMike]

Ian uses AIs for high speed stuff that human reaction times can't handle, but other stuff he feels is best done by humans. His biggest argument against AI is do you want control of high powered weapons with an AI or a human?

 

[Ryan_m_b]

Ian uses AIs for high speed stuff that human reaction times can't handle, but other stuff he feels is best done by humans. His biggest argument against AI is do you want control of high powered weapons with an AI or a human?

That's a meaningless question unless you provide a detailed description of the characteristics and capabilities of the proposed AI.

 

[SHISHKABOB]

a good way to force action sequences or whatever is to make up magical- er I mean fictional chemicals or elements that have some oddly specific behaviors. For example, in the anime series Legend of the Galactic Heroes, there was some funky gas stuff that exploded very violently if lasers or guns were shot through it. Sort of like the laser vs. shields thing in the Dune universe. This forced armies to duke it out in fancy armor, crossbows and giant battleaxes. The rest of the show was about giant space battles where the ships lined up like 18th century European line infantry and space politics.

But they got to add in some really cool face to face melee combat scenes because of some magical gas that they made up.

 

[Ryan_m_b]

a good way to force action sequences or whatever is to make up magical- er I mean fictional chemicals or elements that have some oddly specific behaviors.

That's the cool thing about speculative fiction. You propose some sort of technobabble and explore the societal and practical ramifications. For instance, if this gas explodes violently then can it not also be harvested as a powerful fuel? Simply store it in gas canisters and spray little bits at a time into a laser lit engine. Or store it at very high concentration and then light a laser inside the canister as a bomb.

 

[GTOM]

Yes I watched Legend of Galactic Heroes, i don't know if they used the Zephyr (I think) for propulsion purposes as well.
(Otherwise I disliked that series, Yang always knew what the enemy is planning, they launch a small attack, Send there our whole navy! Yeah why not, next time, they launch a very big attack, and of course it is only a decoy...)

Basically, in deep space, where arent civilans and neutral parties, AIs can't do much wrong...
In case of orbital patrol, human decision is needed, and i doubt that remote control is always enough, there can be spys for example, that can hack the system to create an international scandal or something like that.
Also you have more options to rescue pilots.



I had the idea, that aliens can deploy self-replicating nanobots to Earth, to infect computers, turn our own robots and infrastructure against us...
They want everything to be ready, by the time they arrive.

However, if their plan A fails, they can launch a relativistic torpedo against Earth...
Is it possible to counter, without hyperspace senses or thing like that?
(It is so magical, one could even bring the Force to the image)

Although... if humans can learn the whereabouts of the alien homeworld, they can also threat them with R-torpedos.

 

[Ryan_m_b]

However, if their plan A fails, they can launch a relativistic torpedo against Earth...Is it possible to counter, without hyperspace senses or thing like that?
(It is so magical, one could even bring the Force to the image)

Although... if humans can learn the whereabouts of the alien homeworld, they can also threat them with R-torpedos.

Without magic technobabble like a forcefield not really. The most you could do is fill your system with highly sophisticated gravity sensors to sense the RKV as it comes. You might not have much time at all because if it is traveling at 0.9c (which btw is roughly the velocity an object needs to reach for its kinetic energy to reach half its rest mass) and you detect it at one light day out this means it is only two light hours away. If you do have time you could try to divert its path with powerful lasers or try to through mass in the way to deflect it but I doubt you could really do any of that.

Charles Stross dealt with this issue in his novel Iron Sunrise. In it various factions have STL-deterrents hidden in their Oort cloud operating under a dead-man switch. If they don't receive a signal every X hours they launch towards a target planet (trying to find a tiny ship, possibly stealthed from across a system would be next to impossible). This largely stopped factions invading each other for fear of severe retaliation years later.

 

[GTOM]

If a RKV hits a one kilogram mass before the planet, what would happen to it?
The energy of the collision could turn it into a dissolving plasma cloud or dont?

 

[Ryan_m_b]

If a RKV hits a one kilogram mass before the planet, what would happen to it?
The energy of the collision could turn it into a dissolving plasma cloud or dont?

At around 0.87c the kinetic energy of an object exceeds half it's rest mass. So a one kilogram RKV traveling at 0.87c relative to the planet will have the kinetic energy of e=0.5*c² = 4.5 petajoules = ~10 megatonnes of TNT (~600 Hiroshima bombs). At that speed it would get through the atmosphere in less than a millisecond and cause massive devastation to the area it hit (akin to a nuclear explosion plus an earthquake). Some quick googling tells me that the meteorite that killed the dinosaurs released ~0.5 Yottajoules of energy which would be the equivalent of a 5 kilotonne RKV traveling at 0.87 which works out to be roughly the mass of 50m x 10m x 10m of ice.

This is something that a lot of SF authors forget in their haste to write about relativistic ships the size of super-carriers and cities. The very ships you have littered in your setting as though they were sprinkles on a cake could all be converted to weapons thousands of times more powerful than the meteorite that caused the K-T mass extinction! (this is also known as http://www.projectrho.com/rocket/prelimnotes.php#johnslaw)

 

[GTOM]

I can see, but if you try to put a brick in the way of the RKV well before it hits the planet?
Would that mean, that only the brick disintegrates in the collision, or the RKV also?

 

[Ryan_m_b]

I can see, but if you try to put a brick in the way of the RKV well before it hits the planet?
Would that mean, that only the brick disintegrates in the collision, or the RKV also?

Whatever you put in front of an object traveling that fast would just be disintegrated, like a wet tissue paper thrown in front of an artillery shell. It may slow the RKV down a negligible amount but what you really hope or is to divert its course ever so slightly so that it misses its target. More likely though is that it may cause the RKV to break up but even if it did it wouldn't change the amount of energy that is about to hit: whether it hits the planet in 1 piece or 1 million pieces the same horrendous amount of energy is about to be released.

 

[SHISHKABOB]

my problem with relativistic weapons is how the heck do you aim them properly

 

[Ryan_m_b]

my problem with relativistic weapons is how the heck do you aim them properly

What do you mean? Why would it be a problem to just aim, accelerate it up to a high fraction of C and watch the fire works? If long distance is a problem add some form of sensor and some thrusters to tweak the course. Even a small fraction of a degree course change could have big consequences after light hours-years

 

[SHISHKABOB]

What do you mean? Why would it be a problem to just aim, accelerate it up to a high fraction of C and watch the fire works? If long distance is a problem add some form of sensor and some thrusters to tweak the course. Even a small fraction of a degree course change could have big consequences after light hours-years

this may be a misunderstanding on my part, but wouldn't it take a looot of energy to change the course of something moving extremely fast?

 

[Ryan_m_b]

this may be a misunderstanding on my part, but wouldn't it take a looot of energy to change the course of something moving extremely fast?

Kind of, by engaging in any kind of thrust you change the velocity. Simplistically think of two objects on a grid: A and B with the top being North, bottom South etc.

A is traveling north at a speed of 1 square per second. B is traveling north at a speed of 10 squares per second. Both of them apply thrust so that they are moving west at 1 square per second. For A this means that for every square it travels north it travels 1 west (creating a 45 degree angle if this grid were a graph). For B it travels 1 square west for every 10 north.

However you only have to nudge a tiny bit to be very off course over long distances. Let's posit B (a RKV now) traveling at 150,000,000 mps (~0.5c) and at some point it thrusts to one side (let's say port) so that it is traveling 1 metre to port for every 150,000,000 metres it travels forward. Over the course of a light hour (two hours of travel) it is now 3.6 km off course to port. Over a light year it would be 62,000 km off course!

And that is only supposing it sticks to the measly thrust that generates 1mps to port!

 

[SHISHKABOB]

right, I see now. Usually I imagine relativistic weapons as big chunks of stuff that don't have thrusters on them, but I guess it isn't unreasonable to put things like that on something like that.

 

[Ryan_m_b]

right, I see now. Usually I imagine relativistic weapons as big chunks of stuff that don't have thrusters on them, but I guess it isn't unreasonable to put things like that on something like that.

Without propulsion how do you get them up to relativistic speeds ? For me an RKV is just a spaceship on autopilot; the only difference between a relativistic spaceship and a weapon is how it plans to end its journey.

 

[SHISHKABOB]

well, perhaps you have some kind of accelerator like a railgun, but I can see how making it basically a spaceship makes more sense. Well, a lot more sense :P

 

[GTOM]

Although I am wondering.
Isnt it possible, that with this speed, collision with gas particles and micrometeors, electromagnetic induction from solar wind and magnetic field, will ruin its sensor arrays inside the Solar System?
Than it can still miss the Earth.

 

[Ryan_m_b]

Although I am wondering.
Isnt it possible, that with this speed, collision with gas particles and micrometeors, electromagnetic induction from solar wind and magnetic field, will ruin its sensor arrays inside the Solar System?
Than it can still miss the Earth.

Doubtful, space is incredibly empty, but even if it did all it would take is an accelerometer to sense course changes and an internal map built up from before it went blind would ensure it hit.

 

[GTOM]

I see.

What is your opinion about space fighter carriers?
I know that small ships and big ships moving through the same void... but i had the thought, that theoretically, we could convert our ships to huge airships, but it would be too expensive.

Maybe, for someone, it would be too expensive to fit an interplanetary cruiser with special lower specific impulse-high trust drives and super cooling mechanisms that can grant a fighter superior acceleration on a bigger scale than a not so special interplanetary ship.

I know you can't just dodge lasers and other beam weapons... but it isn't that easy to hit small flies, not even for a computer.

 

[rolerbe]

I like the whoooshing sounds they make. My favorite part!

 

[Ryan_m_b]

What is your opinion about space fighter carriers?
I know that small ships and big ships moving through the same void... but i had the thought, that theoretically, we could convert our ships to huge airships, but it would be too expensive.

Huh? You mean turn aircraft carriers into blips? Firstly that would be one huge balloon and secondly a couple of bullets in that balloon and you're going to have a bad day.

Regarding the fighter/carrier idea it really depends on the technology you have available. Put it this way if you had something like a VASIMR or fusion drive you are going to need to carry a honking great power plant (probably nuclear) to run it. Plus all the fuel, expendables etc means that for anything that you want to be able to operate for more than a few minutes it's going to have to be big. So that's a large amount of specific impulse but low thrust.

Conversely a "fighter" is so small that all it could fit is some sort of chemical drive which massively reduces it's specific impulse but might increase it's thrust. Problem is in what scenario is that helpful? It's hard to know without having a hypothetical military scenario on the table and a list of technologies.