Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Missile defense is NP-complete

smu160.github.io

Post reply on HN
Print view View original

401–410 of 446 posts

Re: Missile defense is NP-complete

#401

Post by standardUser »

elzbardico wrote: post #285
standardUser wrote: post #236

Earlier quoted context omitted.

Take China for an example. No one knows China's true military capabilities, because they're rapidly evolving and because they virtually never use them. If there's an element of surprise to be had, they have it. But that cut's both ways, because China itself doesn't have experience exercising those capabilities. The learning curve could be noticeable. Meanwhile, no one doubts the ability of the US military to execute.

Basically the only country left in the world with expeditionary capabilities is the US. It is hard to compare this with China. Different goals and philosophies.

China is building force projection rapidly. But it's a huge gap.

Re: Missile defense is NP-complete

#402

Post by tokai »

fpoling wrote: post #272
rdtsc wrote: post #237

Earlier quoted context omitted.

Now imagine for the same $10k cost making a cruise missile, instead. This is close to what a Shahed is -- the estimate is $20k-$50k / unit, so close enough. This is bonkers. Countries can now afford for the same cost * to make not a 10-20 mile range artillery shell, but a 1500 mile effective range cruise missile. * Defense costs are "fake" to a large degree. A lot of that is really corruption with money flowing from…

It is vastly more complicated to find targets at 1500 miles than at 20. So drones are effective at destroying big stationary civilian infrastructure and much less at long distance strikes at military targets. Russia's inability to destroy Ukrainian aviation is a good example. But then with solar and batteries civilian infrastructure becomes much more resilient against drone strikes.

No the Russians inability is because they are bad at it. Extremely bad. Ukraine destroy military targets at extreme range with drone all the time

Re: Missile defense is NP-complete

#403

Post by donkeybeer »

trick-or-treat wrote: post #344
falcor84 wrote: post #305

Earlier quoted context omitted.

Yes. Absolutely. If there are invaders who are killing everybody around me and telling me that they'll stop and generally let me be if I surrender and agree to live in a democracy, I expect that I'll be very inclined to accept. Maybe afterwards, if I see it's not working out, I may still consider guerrilla resistance down the line, but I don't see the benefit of fighting and most likely dying just for the sake of def…

Wasting human lives in war is the goal of jihad. This is the part that westerners have a hard time understanding. Why does Hamas hold hostages in tunnels under their own civilian populations? Not because they think Israel will hesitate to bomb there, they know they won't. It's because the death of their own population is a goal in itself.

If wasting human lives in war is the goal of Jihad then America and Israel are the highest and most supreme jihadis in the world for several decades.

Re: Missile defense is NP-complete

#404

Post by roysting »

twoodfin wrote: post #269
roysting wrote: post #100

Earlier quoted context omitted.

There is no amount of math that can make up for the lopsided dynamic of hypersonic missiles. The only reason the “iron/gold dome” con job was even plausible to plunder trillions in U.S. Monopoly money was because missiles were crude, slow, and not MIRVed or had decoys at one time. That was a long time ago though. MIT Prof. Emeritus, Theodore Postol, has been trying to warn about this basic, mathematically proved frau…

MIT Prof. Emeritus, Theodore Postol, has been trying to warn about this basic, mathematically proved fraud for many years now. Indeed, there are any number of very smart people who made up their mind 40 years ago in opposition to Reagan and SDI. Surprisingly, very few of these folks have evolved their position over decades of changes in the strategic and technology pictures: Defensive systems can’t work and are inher…

> Defensive systems can’t work and are inherently destabilizing even though everyone knows they can’t work.

All of those clauses are immensely important for everyone to understand.

First, "can't work"; because the math simply does not math, so to say.

Second, "inherently destabilizing"; among other reasons, if you think your imaginary "iron/golden dome" will protect you, you do all kinds of insane and reckless things that could quite literally at best be civilizational collapse, or even human life ending.

Third; "everyone knows they can't work" is not something I am at all convinced of, or at the very least those who should and really need to know that, don't actually know it, because "DC" is a self-licking ice cream cone that huffs its own farts to the point that the system reinforces those characteristics by selecting for them. The result is that the whole narcissistic system believes its own decadent nonsense.

Re: Missile defense is NP-complete

#405

Post by aftbit »

solatic wrote: post #314
aftbit wrote: post #242

Earlier quoted context omitted.

Shot exchange is a huge problem, made even worse by the arrival of cheap drones. But you're implicitly assuming that the adversary is on roughly equal economic footing. If your defense budget is $800 billion and your adversary's defense budget is $8 billion, you can afford to spend 100x as much shooting down their missiles as they spend lofting them. There's also a danger in projecting linearly from the beginning of…

Defense budget is an abstraction. At the end of the day, there are only so many factories with only so many raw inputs producing only so many interceptors per day. You cannot simply increase the defense budget in the event of a war of attrition and then attempt to outspend your enemy. And this is beside the political unpopularity of high defense budgets in peacetime, when they would need to be higher, to build the in…

All true, and of course the $900B plus defense budget of the USA is not dedicated to interceptors to the same degree that Iran's $8B is dedicated to missiles. Shot exchange is fundamentally an economic problem though. The USA is not going to go broke shooting down missiles - they're going to run out of interceptors. Money is a much larger constraint for Iran than the US, but even there, the real constraint is military and diplomatic.

Re: Missile defense is NP-complete

#406

Post by WalterBright »

srean wrote: post #372
WalterBright wrote: post #335

Earlier quoted context omitted.

Do the drones being launched by Iran have evasive capabilities?

Unlikely but they can be intelligent about their trajectory. That is avoid known areas of resistance, use natural features for protection. Being slow moving as they are, they are quite vulnerable to countermeasures after they have been detected. I expected a-10s, helicopter gunships guarding critical infra, but have not heard of anything like that in the news.

A10s are expensive overkill, and helicopters are too slow.

Piston engine airplanes are plenty fast enough and cheap to build and deploy.

Re: Missile defense is NP-complete

#407

Post by WalterBright »

myrmidon wrote: post #399
WalterBright wrote: post #322

Earlier quoted context omitted.

During WW2, the British used Spitfires to shoot down V1s. The V1s, pushed by a simple pulse jet, I presume are much faster than the drones. So some WW2 aircraft could be re-armed and used to shoot them down cheaply. The British also employed a belt of radar-guided flak guns to shoot them down. I don't hear any comparisons with the V1s, so my idea must be stupid, but I'm not seeing the flaw in it.

I think a big difference is that asymmetry has grown a lot: The modern drone is much cheaper than any manned aircraft (while V1/V2 needed comparable or greater industrial input compared to fighter planes). If you want to scramble manned fighters (even WW2-style ones!) every time cheap drones are launched then the pure material cost per intercept might be acceptable (no guarantee here: you need more fuel and your ammu…

The V2 was so expensive it was rather catastrophic to the German war budget. V1s, on the other hand, were very cheap to make and deploy.

> you need more fuel

Not much of a problem.

> and your ammunition is potentially more expensive than the drones payload

I'd say it's on par. A few rounds into a slow moving target moving in straight line would be easy to hit.

> the pilot wage/training costs alone ruins your entire balance as soon as there is any risk of losing the interceptors (either from human error/crashes or the drone operator being sneaky).

The US somehow managed to train an enormous number of competent pilots in WW2. I doubt there would be any shortage of men eager to fly them and "turkey shoot" the drones down. And there'd be a lot of mechanics falling all over themselves to build those machines!

Re: Missile defense is NP-complete

#408

Post by WalterBright »

watwut wrote: post #382
WalterBright wrote: post #326

Earlier quoted context omitted.

Fighting is rational when the alternative is being killed. FDR made a big mistake announcing that he was going for unconditional surrender. This resulted in Germany fighting to the bitter end. Hitler dragged it on to the last few hours - he knew what was going to happen to him when the war ended.

It was not mistake. Nazi dragged because they had to due to own ideology. But allies had to achieve clear military victory, because of WWI aftermath. Germany did not believed it lost, it believed it was betrayed and wanted do-over. No surrender thing was to prevent next round with WWIII as Germans feel like betrayed again.

The Germans had a saying at the time: "enjoy the war because the peace will be hell".

They were correct.

> Germany did not believed it lost, it believed it was betrayed

The citizens were not that stupid. They knew by 1944 that they were going to lose. All they had to do was look up, and see the ever-growing endless streams of B-17s overhead. They knew what the Red Army was going to do to them. They knew payback was coming from the Allies.

Re: Missile defense is NP-complete

#409

Post by srean »

WalterBright wrote: post #406
srean wrote: post #372

Earlier quoted context omitted.

Unlikely but they can be intelligent about their trajectory. That is avoid known areas of resistance, use natural features for protection. Being slow moving as they are, they are quite vulnerable to countermeasures after they have been detected. I expected a-10s, helicopter gunships guarding critical infra, but have not heard of anything like that in the news.

A10s are expensive overkill, and helicopters are too slow. Piston engine airplanes are plenty fast enough and cheap to build and deploy.

Now that comes from an authority :)

Re: Missile defense is NP-complete

#410

Post by ghywertelling »

rdtsc wrote: post #282
fpoling wrote: post #272

Earlier quoted context omitted.

It is vastly more complicated to find targets at 1500 miles than at 20. So drones are effective at destroying big stationary civilian infrastructure and much less at long distance strikes at military targets. Russia's inability to destroy Ukrainian aviation is a good example. But then with solar and batteries civilian infrastructure becomes much more resilient against drone strikes.

> It is vastly more complicated to find targets at 1500 miles than at 20. It's true but they are so cheap that launching a whole bunch and/or improving them incrementally is possible. Yeah they are for stationary targets mostly, for sure. And of course their sounds and relatively low speed does make them somewhat easier to shoot down with short range AA guns and can have automated acoustic early warning system (it's…

https://youtube.com/shorts/JIXdkKBFw-4

Radars can be fooled with this simple physics hack called Lunenberg Lens

Post reply on HN