Dausuul

That's why I mentioned a heat sink, also known as "a big block of ice that keeps the ship cool." You are, of course, limited by the length of time it takes the ice to melt (or sublimate, or just warm up, depending on what kind of ice you've got). If your mission isn't done by then, you're screwed. However, while the ship is coasting, you only need to absorb as much waste heat as the life support systems and the crew members' own bodies generate. If the crew compartment is small relative to the size of the ship, this should be doable. Accelerating up to speed does pose a challenge, and may not be possible to accomplish stealthily. However, nobody says you have to stay with the engine that's gotten you up to speed. Ride on a booster rocket which accelerates hard and alters its course frequently. At some point, separate from the rocket and leave it to continue on its course-changing way. The enemy doesn't know when you separated or what your course was when it happened. If they're watching the rocket, all they're going to see is the glare of its drive going full blast. The nice thing about space is that once you're up to speed, you can coast to your destination. A directed energy weapon travels at the speed of light. The enemy's first observation of the weapon will be when it hits them (well, maybe a couple of seconds' warning if your weapons throw off energy while preparing to fire). At that point, your stealth mission has been successful. You can quit sneaking around, fire up your main engines, and blast out of there. Again: You don't have to be stealthy forever. Just long enough to get where you need to be and do what you need to do. I've read many of those discussions, and it looks to me as if the "stealth is impossible" side relies on some very unrealistic assumptions--most notably, that your ship must be able to remain stealthy indefinitely, and that you must be able to accelerate hard in stealth. Saying that stealth in space is difficult and limited (indisputably true) is very different from saying it's impossible.

Hmm. I'm going to start by assuming a few definitions here: "Capable" --> "Possessing the engineering know-how to construct such a ship, such that if we decided to do it, it would be just a question of money." "Interstellar travel" --> "Moving living human beings, or the mind-uploaded equivalent, to another star system such that when the ship arrives, there will still be living human beings (or the mind-uploaded equivalent) aboard." I'm not going to require that the ship actually be able to get to another star system before 2100, just that it could be launched by then. ...And I'm still gonna say no. I am reasonably optimistic about technology and I do think the human species (or the MUE) will go to the stars one day, if we don't bomb ourselves to extinction first. But within this century? Highly doubtful. We're still struggling just to get off the ball of dirt we live on. We'll be doing well to colonize Mars by 2100, let alone Alpha Centauri. It is just conceivable that we might launch an unmanned probe to another star system by the end of this century. (Voyager doesn't count; for something to be a probe, it has to be able to, you know, probe things, and report back on what it finds. By the time Voyager gets to another star system, it won't be a probe any more, just a funny-looking meteor.) Even then, however, I would bet against.

I refer you to a weird technobabble device called a "thermos." Yeah, I know, totally violates thermodynamics. It's physically impossible to carry a container of hot coffee without burning your fingers. Can't be done. This is why I find the "STEALTH IN SPACE IS IMPOSSIBLE" arguments hard to credit. It may well be that the engineering problems involved make stealth impractical. But the naysayers feel it necessary to resort to absurdities like the above. Really? It's physically impossible to keep a ship from radiating IR for the duration of a mission? Hogwash. You don't have to be stealthy till the end of time--just long enough to get where you need to go and do what you need to do. As long as you can keep the outer hull cool and shunt your waste heat into an internal sink, and finish the mission before the heat sink warms up, you're good. Then you can sit there happily radiating IR all over the wreckage of your hapless enemy. As I said, this may turn out to be impractical, or may be practical only for unmanned ships and/or short missions. Fine. That's a reasonable debate to have. But impossible? Come on.