Does physics forbid such a device; a heat destroyer

DaleSpam

Honestly, it is much more important that your characters be compelling and the plot be interesting than technical details be correct.

Deeviant

For most stories, yes that is certainly true. However, I am rather uninterested in human emotion and motivation; I am far more interested in the fate of humanity and future of our universe.

However, I don't want to full into a pedantic cycle of physics nit-picking, I want to look into the future.

mfb

I am highly confident that human emotions and motivations are of crucial importance for the fate and future of humanity.
I do not want to give any estimate for the influence of humanity on the future of the universe, and I do not even have a measure which would allow this.

Where is the problem with large radiators then? It is just an engineering issue, and it is usually fine to assume that those are solved in science-fiction.

Deeviant

The problem is that it doesn't not accomplish the goals I had in mind(I mainly wanted a device that could absorb and convert latent waste heat).

To give you a better picture of what I am working toward, picture this; In the future of space craft warfare, all the scenarios I have come up with is that you are completely out of luck as far as defensive systems go. I see no feasible way to create a star trek style "shield", nor any reasonable way to armor a spaceship that would be in any way capable of standing up to even the weapons we could build now, let alone weapons of the future.

Thus, I see only one defense left: stealth. The hulls would be built for stealth, and one important requirement for that would be that the hull would need to cool, specially so it does NOT emit large amounts of highly detectible EM radiation via black-body. And it must remain cool despite housing a large generator of some type inside it.

If anybody has any crazy ideas for possible defensive systems that physics may allow, I would certainly like to hear it, but I could not even think of a system that could sufficiently protect a ship against a large thermonuclear bomb. There just doesn't seem to be any good physics here to grab on too; magnetic shielding would only work against charge particles and requires too much energy anyways, a simply material based approach seems to fail against the furiosity of possible weapons, mirroring might be effective against one of the most obvious space-based weapons(laser) but would completely defeat the stealth idea and would be completely ineffective against kinetic or other more exotic weapons.

So, I would foresee that a futuristic space ship intent on warfare would somewhat resemble a submarine, not in shape or operation, but in general philosophy. For this reason I imagine a black EM absorbing hull, some method of dumping heat that doesn't act as a beacon, a inertial/kinetic propulsion system as simple as accelerating masses to significant fractions of light (which happens to double as a weapon system).

I have however, conceptualized a few ideas which do bend the rules a bit. For instance:

"Hawking" generators/weapons: Using some unknown process normal matter is condensed and compressed past it's Schwarzschild radius, creating an non-gravitationally induced black hole. Such a small black hole will then almost immediately evaporate via hawking radiation in the form of EM radiation, funny enough this is also a black-body emission. This would allow one to convert mass directly into energy without an matter/anti-matter reaction. I may be wrong, but I assume it radiates energy equivalent to the starting mass as well as the energy introduced via the compression. Other than the obviously enormous challenge of compressing matter to such a degree, I am reasonably sure this idea is in line with accepted physics. Obviously, this would also serve as a tremendous weapon; perhaps have an anti-matter kicker that provides compression energy then resulting in a center mass finding itself within it's own Schwarzschild radius and almost immediately converting itself into extremely hard EM radiation(the temperature of a 500 metric ton black hole would be 2.454406e^17 K, found with this very nice black hole calc ap http://xaonon.dyndns.org/hawking/). Anti-matter is obviously very powerful itself and extremely possible, but has many problems, which the Hawking devices overcome; there is no ready source of anti-matter so it will never be an energy source but rather a most effective means of story and concentrating energy, and anti-matter explosions are nearly as big as you think they would be since it is very hard to get each atom to combine considering the extremely energetic reactor, in fact most anti-matter would likely be wasted with only a small amount actually being converted.

Drakkith

Well, you could have all ships come with a cooling system that routes the heat to a specific location where and deposited. The resulting radiation is focused into a collimated beam and emitted in a specific direction. Unless you are in the direct line of this beam then you cannot detect it. I can think of a few situations where it would be useful in the book, such as a "lucky break" in detecting an incoming attack by a patrol that by chance stumbles in line of site of this beam.

For defending against nuclear warheads, a laser of some type, perhaps UV or X-Ray could be used for destruction of the warhead before detonation. A nuke in space must be very very close to damage something, as most things in space are many many kilometers away from each other.

DaleSpam

I don't think this is bending the rules as much as you might think: http://arxiv.org/abs/0908.1803v1

Drakkith

That. Is. Cool.

mfb

In this case, I have bad news for you.

You can direct the radiated heat to some extent, but if the enemy is prepared for that the spaceship cannot really hide.

Deeviant

That was an interesting page, with a rather large amount of thought placed into it. However, it really seemed like they came up with a conclusion and then filled in the blanks.

Really though, the only point that I agree with is the black-body radiation is going to be a problem, hence the creation of this thread in the first place. One of the points they seem to keep going back to is that a ship has to have some huge drive plume, this is not at all I how I envision my ship, they will accelerate basically by using a mass driver, which doubles as a weapon. Radar could be easily defeated, a telescope would extremely hard pressed to pick up black ship(which could also have technology to light up it's hull to mimic the background stars behind it).

If push comes to shove, I use a black-body pumped laser and lase the energy out into space in such a narrow beam, a detection systems would simply not be useful. (http://www.freepatentsonline.com/3614663.html).


Still though, I want my heat destroyer =/

mfb

If you know the position of the enemy (and therefore the position on the ship you have to light), which is somewhat strange as you try to make ships invisible (and probably not just the own one). As alternative, you could have light emitters everywhere. In addition, you should try to reproduce the spectrum.

Your mass driver can have a high efficiency, sure. The required high acceleration is not trivial, but might be possible. However, the exhaust is not the main point. As soon as your ship has warm parts, it also needs some blackbody radiation.

Plastic

what is heat?

radiation? -> photoelectricity.
kinetic energy of a large particle? -> you could annihilate that particle with antimatter and harvest the resulting radiation, destroying the 'heat' in the process.

DaleSpam

As described, you cannot absorb and convert latent waste heat to work without a cold reservoir, and even then you are limited by Carnot. However, here are three ideas:

1) They have developed a way to greatly expand their effective surface area for radiation. The bigger the surface area the closer to 2.7 K they can radiate with the radiator serving as the cold reservoir. Since it is slightly higher than 2.7 K the blackbody spectrum would be slightly different, so could still be tracked. But it could be made arbitrarily difficult by making it arbitrarily large.

2) They have developed a way to exchange heat directly with deep space at 2.7 K as the cold reservoir. Although there is no known way to do it, it does not violate the second law of thermo (but it might violate some other laws, I am not sure). In principle, there would still be energy leaving the ship, even if it were at 2.7 K, so there may still be a way to track it.

3) Military ships could be equipped with a material of very high specific heat capacity which is actively cooled down to a few μK (requiring substantial work) during "off duty" times. Then during operations that material could be used as the cold reservoir and the hull kept at 2.7 K without radiating. That would limit the time that they could be stealthed by the amount of time that it would take to heat up the material.

rorix_bw

You do it the same way we do it today. Shoot the missile or jam its radar.

I suggest researching modern warfare especially air and sea. This is almost all electronic now (no more dogfights!). We have both hard and soft kill systems in use today, for preventing missile hits. Modern warships are not significantly armoured in way that World War II ships were, or that tanks are.

Hard kill involves shooting the missile. There are a number of systems for this e.g. AEGIS air defence system on the US Navy "Burke" class Destroyers. This was designed for air defence (against missiles and aircraft) but is now being adapted to defend against ballistic missiles (it has hit them in tests: give it a few more years). The premise of the system is that you fit surface-to-air (SAM) missiles to a ship, add a very sophisticated air defence radar, and theoretically (if it all works, and the crew all do their jobs) you can stop missiles and aircraft from reaching you.

I haven't seen any classified data on this but you can assume it *probably* works as follows: It has 90 missile cells. Each cell holds a single long range surface-to-air missile (SAM), or 4 short range ones (the new ESSM 4-packs). It will shoot 2 of the long range missiles at each incoming air target at about >100km range and each missile *probably* hits 0.5 of the time. At about >50km range it will shoot 2 of the short range ones at any "leakers", with almost certainly higher pH. At point blank range it will use a single RAM missile vs any leaker. In tests, RAM has a 0.9 pH.

I don't know what range they are hitting ballistic missiles at. Ask me again in 10 years. Space combat would probably be extending the ranges.

Soft kill can involve electronic jamming (ECM "Electronic Counter Measures"). For example radar "decoys". These rely on the fact that a missile must somehow be able to find its target by itself (unless you want to put a pilot into it) and do this it has a radar. The radar works by giving off signals that bounce back from the target and by detecing the reflected signals, the device locates stuff. By transmitting "false echos" you can confuse a radar.

An example of such a system is "Nulka". This is a rocket that you launch from a ship, which can hover close to the sea, and gives off signals, making it look, to the small computer and basic radar in a missile, like a ship. Remember that if a missile "misses" it may not be able to turn around and re-attack: Only a small number of modern missiles can turn around for a second go (fuel limit, computer limit, maneuvering limit, G-force breaks the fins off etc) and they can be shot as they turn.

There are also various "ECM" devices that comprise transmitters mounted on the ship itself, that can emit signals, that have the same effect. e.g. "SLQ-32". The large computer on a warship is much smarter than the smaller one on a missile.

More primitive systems used "chaff" which could be described as "reflective confetti" and produced a cloud on the radar that obscured the targets. One even launched a net at the missile (that didn't really work, but in space you might use a gun that shoots a glob of expanding foam or something to catch the missile, then it can have bomb or a TASER or something in the foam cartridge - net projectors certainly have worked in the past). A basic metal grille should stop a missile, if it hits it hard enough to hurt itself ...

Finally, and this sounds crazy, but you also have to locate the target before you can shoot a weapon at it. I don't mean stealth, I mean: Say there's a CVN (aircraft carrier) attacking you, that you want to get rid of. OK, where is it? It's not going to be in sight of the coast as it can strike from over 1,000 kilometers away. (In space, it's painted black and in any case they probably parked it behind the moon and are sending drones out around the moon to attack you. "Behind the moon" is a big place.)

First, your radar and camera satellites don't cover the entire ocean. There are gaps and because their orbits are known, the carrier can sail between them: (no joke, USA used to do this to Russian RORSATS [Radar Ocean Reconnaissance SATellite) but it is harder now with more satellites (a lot harder). However, USA, Russia and China have all demonstrated the abilty to shoot satellites. In space, radar satellites aren't going to be as lopsided as they are on earth - they will be be just extra spaceships.

Second, the carrier has a sea control zone of several hundred kilometers in any direction created by its air patrols. Your own scouts and satellites entering this zone are certainly going to come under attack well before they cross the "radar horizon" at the point at which they can detect the carrier due to line of sight over the curve of the Earth or in our case "behind the moon". If the scouts have their own radars on, this is even harder as a radar is like a searchlight: The guy you are looking for can detect you very easily by the beam from your searchlight, and will see you before you see him; it's quite easy therefore for him to shoot his rifle at the light then move to a new place - don't stand next to the guy carrying the light - the equivalent to this is a missile that homes in on active radars. There's also missiles that home in on jamming sources - it's a never ending cycle of weapon vs counter-weapon.

Even if your missiles are set for "bearing only launch" with a wide search pattern (Mr Missile, please fly 500 km in direction A then turn on your radar and look for ship targets over 100 meters in length) not only to the missiles themselves also have to survive, and not get their radars turned off, they are as likely to prang an oil tanker as they are the enemy warship. That's probably less likely in space but you never know ... one assumes you will fight for control of planets, and not randomly in deep space.

Finally, if you're in space and using nukes, note that in space, you're going to have land a nuke very close, as there is no atmosphere to create a pressure wave. There's also nothing stopping the other guy using nukes to counter your nukes. He doesn't need to destroy the missile, just damaging its electronic systems is sufficient.

Missiles can evade (modern anti-ship ones do, they are programmed to make radical maneuvers as they near the target to make it harder to hit them) but essentially they have to get within a certain distance of the target so their destination is known, and they do have a big heat source from their engine and a big searchlight on the front called a radar, so they aren't exactly hard to see.

Guns also can be effective against missiles. The reason gun-based defences are being superceeded with electronics and counter-missiles in modern warfare is due to the limited range of guns vs the speed of modern missiles. However, in space with access to lasers and railguns etc, this may be less of a factor. A gigantic "shotgun" may well be able to deal with incoming missiles.

One other thing to consider, you can stick a gun or submunition on a missile. For example a bomb-pumped X-Ray laser. This is supposed to be a nuke that explodes and directs its force forwards via rods that channel the blast; it's sort of a one use laser that doesn't require you to get close to the enemy. Today we have thing like "subroc" which is a missile that launches a torpedo (because the range of a torpedo is limited, and it does not require a separate torpedo system to launch it); many mines also don't explode, but instead launch torpedoes. You could have a single "bus" vehicle that would spit out submunitions - small anti-missile missiles - in the vague direction of any incoming missile.

Some wikis to check out

http://en.wikipedia.org/wiki/Ballistic_missile_defence

http://en.wikipedia.org/wiki/Nulka

http://en.wikipedia.org/wiki/Aegis_Combat_System

http://en.wikipedia.org/wiki/Electronic_countermeasure

http://en.wikipedia.org/wiki/DDG_51

http://en.wikipedia.org/wiki/SLQ-32_..._Warfare_Suite

BTW: I just remembered there have been nuclear tests vs warships. You have to get considerably closer than most people would imagine ... and that's with an atmophere. They have positively pressurised super-structure and decontamination wash-down systems now on warships. I'll to find the results in Google but that is something you may wish to look for.

EDIT: I also remembered the "medium problem". This is "a missile is faster than a sea ship because it moves in the air, and not the sea". But a missile is not significantly faster than an aircraft ... and only recently (e.g. Spearfish @ 70 knots) have torpedoes been faster than ships or submarines.

The Russians actually built a submarine (Akula class - NATO name, Russian "Akula" is a different class) with sufficient speed to outrun the American torpedo of the same period, and the American SR-71 "blackbird" airplane was able to outrun anti-aircraft missiles. The actual missile had similar speed to the plane, but since the missle had to close, if the aircraft saw it and altered course, it would pass behind.

Deeviant

Ok, I think I am still managing to misunderstand you. You say we can not exchange head directly with deep space this day, but my understanding is: it happens for free via black body. The ISS is current exchanging heat directly with deep space right now as we speak, is it not? Or are you taking about some other sort of mechanism, I don't understand what you mean by "is no known way to do it".




@rorix_bw:

I think you are thinking too much in terms of today's battle scenarios. Think of a perfected electro-magnetic slug shooter a future ship may pack; let's say this thing accelerates a slug to 99.99% C. Then let's say it fires a slug at your ship the same instant a photon bounces off the ship and heads your way; the slug would only be a bit behind and that photon hitting your ship would be the first moment you could even possibly realize the ship fired a projectile at you in the first place, let alone avoid it somehow. For all intents and purposes, the thing would be like a laser that shoots bullets. Prototypes for this type of weapon technology exist today, albeit at much slower velocities(although they have to deal with air resistances and a ship obviously would not). And the thing is, I don't even think the future ship would use a railgun but something far worse that we haven't thought up of yet, my point is if beefed up versions of today's technology already defeats any kind of defense I can dream up; then defensive ship technology has only one fallback: stealth.

DaleSpam

Sorry, I was definitely unclear there. I meant that there is no way that I know of to directly use deep space as a 2.7 K cold reservoir in a heat engine.

Deeviant

I think most space probes use the 2.7 K cold reservoir in a heat engine today. I.E. the voyager probes use a plutonium powered thermopile. Plutonium heats up one side of a peltier device and the other side is cooled via black body directly into space.

rorix_bw

Gaussian Beam

While composing a reply I was wondering if someone knows: is a gaussian beam the best you can focus a laser to? Can you actaully focus it better than this so it retains its full intensity (same beam width) over a longer distance? Wikipedia isn't clear on this, it only says that some lasers can be gaussian. I know I don't have to link to here, as many guys will know already, but I provide for convenience so you can see what I read, not what the truth is :-)

http://en.wikipedia.org/wiki/Gaussian_beam