What future space combat would really look like • Hacker News Board

Re: What future space combat would really look like

#151

Post by jdowner » Wed, Dec 28, 2011, 2:20 AM UTC

arethuza wrote: post #52

jasonkester wrote: post #28

I think Banks' The Algabraist got it about right. In fact, that whole book is crammed full of good "things we currently believe to be true about physics extrapolated as far as theoretically possible" ideas: "How do you navigate this thing?" "Point." "Point?" "Yes, point. It's all about having enough power. Fiddling around with calculations about DeltaV is really just a sign that you don't have enough power."

"It's all about having enough power." That really does sound like the name of a Culture GSV. [Correction - No Culture ship would be quite so lacking in gravitas, so I suspect a more likely name would be "Fiddling around with calculations about DeltaV"].

I would say there is a good chance that a GSV would have no gravitas and that a GCU would have very little gravitas indeed.

Re: What future space combat would really look like

#152

Post by scythe » Wed, Dec 28, 2011, 2:25 AM UTC

ew wrote: post #58

It was definitely an interesting read, however, I feel that fundamentally, for humans to reach the point where space combat is even feasible we will have solved so many more important problems that there won't be a need for fighting in the cosmos. Earth, in general, is at peace. We are largely struggling against terrorism, radical groups, and internal genocide rather than full scale, nation-on-nation wars. No two dem…

>No two democracies have gone to war, ever,

India and Pakistan?

Re: What future space combat would really look like

#153

Post by jerf » Wed, Dec 28, 2011, 2:52 AM UTC

makmanalp wrote: post #139

patio11 wrote: post #16

Earlier quoted context omitted.

Physics. Attacker gets arbitrary mass (reactant, etc) and time to accelerate. Defender needs same mass/time to decelerate... after discovering the attack. Note that you could literally prep an attack for millennia which would be discovered a matter of hours prior to ending a civilization. Physics makes for sucky narratives. Good thing it also makes for a vast, dead, boring universe.

Well, since you're going to skirt around how the acceleration actually happens, I'm just going to counter with: The defender also has arbitrary time to defend. Couldn't you "store up" a defense over time somehow? Maybe have a counter-projectile orbiting really fast that can be brought out of orbit to hit the incoming one? Or, I know we don't have energy shields, but with the amount of assumption going on in this whol…

"orbiting really fast"

That is an oxymoron. You are either orbiting or going "really fast" but you can not be doing both. (In the context in question single-digit miles per second is not "really fast", it's just the cover charge.) You can pour arbitrary amounts of energy into a kinetic kill projectile, and there is no known reasonable way of defending against such a thing except to not be where it hits.

Just as people worry about nuclear weapons and biological weapons, we get planet-killing kinetic projectiles rather earlier than we get anything else useful from space. In fact if we put our minds to it, and were willing to be patient, we could probably do it today. The same tech we're looking at to divert existing planet killing asteroids can just as easily be turned to tweaking one of their existing orbits towards us instead of away.

Re: What future space combat would really look like

#154

Post by duck » Wed, Dec 28, 2011, 2:56 AM UTC

weavejester wrote: post #137

sliverstorm wrote: post #132

Earlier quoted context omitted.

Until you can fabricate matter in your MrFusion6000, material resources in some form or another will continue to be valuable. Once you CAN fabricate, Einstein tells us you will need a TON of energy to do so. So, even if that day comes, you will still need to acquire energy.

Sure, but even today, raw material resources tend not to be the sort of things criminals target directly. You rarely get thieves trying to steal lumber, or iron ore, for example, because they have a low price-to-weight ratio.

How about copper? We had someone steal it from the crawlspace of a house we rent out.

Re: What future space combat would really look like

#155

Post by electromagnetic » Wed, Dec 28, 2011, 2:57 AM UTC

troels wrote: post #115

talmand wrote: post #95

Earlier quoted context omitted.

What if the goal is to eliminate the planet-side species? Plus I'm willing to bet you could obliterate the surface of the planet using kinetic weapons and still have plenty of resources left over.

Why would that ever be a goal?

Why wouldn't it be a goal? If you're fighting over space resources and destroy their space-based military, then its safe to assume the planet bound will soon be launching missiles at you.

The obvious plan is glass the planet, spend 50 years harvesting the orbital resources and then you'll have the infrastructure in place to strip mine the lifeless planet.

Re: What future space combat would really look like

#156

Post by electromagnetic » Wed, Dec 28, 2011, 3:37 AM UTC

johngalt wrote: post #27

The author underestimates guns while overestimating "kinetic missiles". Speed imparts a lot of energy, but it wont transmit all of that energy to the target. You'll have a hole in the ship. Your ships are closing at 1000km/s and your cloud of missiles have a 10km/s Delta? A cloud of slugs would be almost the same, and you could put up a lot more of them. Of course a hybrid approach is likely, with shrapnel filled mis…

Railguns are worthy of note, but would likely only be worthy of PD weapons. The problem with guns is that your target moves. With the exception of missiles, every fraction of the speed of light slower your weapon is, the bigger chance you take of missing. With a round fired at .1C over 300,000KM (1 light second) you need to account for about 11 seconds of lead on your target. That's 11 seconds that they don't change their course enough for you to miss. Compare this to a laser where it's 1 second of lead.

> With the speeds/distances involved all of the missiles would be approaching from a very narrow cone, and a small deflection would mean a miss.

Not necessarily. Unless space battle becomes solely a chasing game (which would favour the defender as if you know you're a runner the majority of your PD's will be aimed out your ass). A missile can sit for any amount of time after being dropped before firing. This means you can distribute a missile or approach from opposing angles. If your ship uses turrets for PD then you know it cant easily shoot two different angles at once. If you're fighting well within your missiles ranges (because fighting at maximum range gives too much time for PD's) then it'll be very easy to launch your missiles around your target in a flank attack.

Re: What future space combat would really look like

#157

Post by saturn » Wed, Dec 28, 2011, 3:46 AM UTC

jasonkester wrote: post #28

I think Banks' The Algabraist got it about right. In fact, that whole book is crammed full of good "things we currently believe to be true about physics extrapolated as far as theoretically possible" ideas: "How do you navigate this thing?" "Point." "Point?" "Yes, point. It's all about having enough power. Fiddling around with calculations about DeltaV is really just a sign that you don't have enough power."

Let me second this recommendation that anyone with a genuine interest in this topic check out The Algebraist; it's a truly excellent book. I wouldn't say it's Hard SF but it's pretty firm and, IMO, a far more considered and imaginative vision of viable-ish space battle than the linked article manages.

I mean, the article hardly even mentions antimatter, aka the most potent energy store in the known physical universe, aka God's battery. Who's going to be frigging around with some stupid dirty fission reactor when the local Dyson Sphere is producing cheap (by military standards) AM by the kilo?

Re: What future space combat would really look like

#158

Post by schiffern » Wed, Dec 28, 2011, 3:50 AM UTC

troels wrote: post #115

talmand wrote: post #95

Earlier quoted context omitted.

What if the goal is to eliminate the planet-side species? Plus I'm willing to bet you could obliterate the surface of the planet using kinetic weapons and still have plenty of resources left over.

Why would that ever be a goal?

You should read The Killing Star: https://en.wikipedia.org/wiki/The_Killing_Star

Spoiler Alert!

In the late 21st century, Earth is at peace, sending fleets of Valerie spacecraft to the stars. Without warning, relativistic kill vehicle obliterate the surface of every planet, and a mop-up fleet of ships begins hunting down the humans that remain.

The last two humans on Earth are kept as zoo specimens. They ask why their planet, and all its species, were exterminated. The squid-like aliens explain their logic thusly:

1. Every space-faring civilization is capable of planetary extermination.

2. If given the choice, every species will choose to exterminate another species rather than their own.

3. Each side knows that the other has the same choice.

Re: What future space combat would really look like

#159

Post by amalcon » Wed, Dec 28, 2011, 3:59 AM UTC

zeteo wrote: post #134

amalcon wrote: post #118

Earlier quoted context omitted.

It's an interesting read, but that scenario could only occur due to imperfect information. With nearly-perfect information (like what would be available in space), the German defenders would have been mobilized ahead of time, and it would have been a straightforward battle.

Read the entire section... the point is about what Wittman did with a single tank and no orders from his superiors. Yes, he had radio on that tank.

I did read the entire section. My point is that the whole scenario only arose due to an information gap.

Re: What future space combat would really look like

#160

Post by sliverstorm » Wed, Dec 28, 2011, 4:20 AM UTC

brazzy wrote: post #145

sliverstorm wrote: post #129

Earlier quoted context omitted.

You can argue this over in your head a lot, but it's really quite simple in my mind. If we assume space travel becomes relatively easy (that is to say it is used for more than initial colonization) there will be interstellar commerce. If there is unprotected commerce, there will be pirates. Any time there are pirates, protection will develop. Let us call these peace-keepers the Navy. If you engage in commerce and you…

Read TFA, it argues pretty convincingly that there will not be pirates because A) you can't hide in space and B) Any ship is a WMD, so governments will do anything to keep them out of the hands of criminals, and protection rackets would be a far more profitable use for them than raiding commerce.

You could apply the same arguments to why wooden naval combat shouldn't have happened.

You'd think there is nowhere to hide on the ocean- but there is the horizon to hide behind (planets anyone?) and weather (electrical or magnetic storms?) to hinder visibility.