Nuclear weapons were billed as being able to make war obsolete. So far, war is doing fine.

Compared to the state of the world before World War 2, we are experiencing a period of relative peace.

long-distance war you propose can’t happen because it’s too inaccurate.

I’m could answer with your own words: “Just because it’s very hard to imagine doesn’t mean it won’t happen.”
But I won’t since both arguments are tenuous. The first one argues technical details in a yet not developed technology. The second one cuts both ways. There are plenty of examples of technology that seemed awesome but just didn’t work out. Flying cars anyone?

I’m pretty sure the guy who invented the printing press had no idea how powerful and far-reaching his invention would be.

Considering the ongoing downfall of the print media, that’s an unfortunate
analogy . I don’t really see how it applies to this discussion either.

Shoot down or jam the GPS satellite systems and the radio waves, throw up enough smoke, etc, and the drone can’t get its orders or carry out its assignment.

It seems to me like you are grasping for straws. Under this circumstances, a human pilot wouldn’t be able to get anything done either. The air fleet will slowly but surely be replaced by UAVs. In fact, this has already happened for reconnaissance aircraft.

Humans are going to Mars for reasons other than the novelty, and humans will still be needed in the driver’s seat eventually.

And yet the only explorers of Mars were robotic rovers and the only ongoing expeditions to Mars are robots too. I agree, humans will and should eventually get there but for any given task – warfare included – sending humans is hardly the first choice.

I may have gotten a little off track there, but the point to be made is that the long-distance war you propose can’t happen because it’s too inaccurate. So long as humans covet what other humans have, there will be a need for war. And where there is a need, someone will fill it. They can’t fill it with inaccurate planet vs planet superweapons, they have to do it with ships and guided bombs and such.

Just because it’s very hard to imagine doesn’t mean it won’t happen. I’m pretty sure the guy who invented the printing press had no idea how powerful and far-reaching his invention would be.

I also doubt that this is the last generation of manned combat aircraft. Maybe drones will become all the rage, but an enemy will simply have to find a different way to win. Shoot down or jam the GPS satellite systems and the radio waves, throw up enough smoke, etc, and the drone can’t get its orders or carry out its assignment. Humans are going to Mars for reasons other than the novelty, and humans will still be needed in the driver’s seat eventually.

Let me comment on some of them:

Giant lasers are extremely expensive [...] Bullets are cheap

Claims are these are extremely speculative. At this point, pretty much everything you bring with you in space is prohibitively expensive. There has been no significant drop in the prices for bringing stuff into orbit. There aren’t any viable strategies to bring the prices down. It just takes a ton of energy, there is no way around it. Same goes for heat signatures. Yes, heat is a an issue with current spacecraft. The ISS has significant Radiators just to drop the heat it receives from the Sun alone.
http://spaceflightsystems.grc.nasa.gov/Constellation/T&V/images/P-1017-11%20ISS%20Radiator.jpg

The bottom line is that space is a remote and hostile environment. It’s difficult to keep humans alive there as it is. We may find better ways to deal with it. But bringing weapons up there is similarly silly and pointless as hauling a Howitzer up the Mount Everest.

Spotting planets is possible because of multiple years of intense observation of a very narrow segment of sky under near-ideal conditions, and with very specific detection parameters.

True, but the advancements in our ability to spot objects from after are much more dramatic than the advancement in our ability to actually go there. It’s also cheaper and involves no risk at all.

So, due to the inaccuracies involved, it will be necessary to send warships to conduct precision bombing and invasions, and other spacecraft will be needed to fend off those craft. The difficulties to overcome are legion, but there will have to be a way for it to happen. Will it be like in games and movies? Probably not. But it WILL happen, you can be sure of that.

I don’t feel like this is really the conclusion from your arguments. All you have proven is that warfare in space is really, really complicated. I claim that it is in fact so complicated that it will actually not happen at all. There will be technological breakthroughs in the meantime which will most likely change the whole idea of war. You can see the changes right now actually. I give you an example: The current generation of fighter Airplanes is the last one. There will be no manned air combat anymore. Drones are cheaper and more effective. Now take a look at an X-Wing. The idea of warfare this fictional vehicle is based on is becoming obsolete already. And of course, we don’t see the elephant in the room: the last war against two world powers was the cold war. A situation vastly different from previous engagements. Two opponents sitting on a stockpile of weapons capable of wiping the other guy out automatically and remotely.

One of the most surprising things I learned was that at space-combat distances, lasers are little better than high-powered flashlights. A realistic laser has to be very big (feet in diameter) and use a high-energy wavelength (UV, X-ray) to focus down to a spot which will cause damage to a target at even one light-second. It’s also got to put out a lot of power.

Another surprise that us regular folk don’t consider is engineering accuracy into the shot. You’ve got to compensate for the weapon’s varying heat as it discharges, the vibrations of your ship, the maneuvering of your ship, the maneuvers of the opposing ship, it’s position in 3 dimensional space, any intervening matter (dust, countermeasures, etc), and so on. The difference between a perfect hit and an imperfect hit can easily spell the difference between causing damage, just warming the hull a little, or missing altogether.

However, one thing sci-fi games rarely take into account is heat. From waste heat to insolation to incoming energies, it’s just not taken into account because it’s such a problem. It is considerably easier to use your laser as a heat ray instead of as a laser – many fewer of the above engineering challenges to worry about because we don’t have to focus on a tiny spot – and simply kill the life-system of a ship. You may not get an instant kill, but the crew will be dead within a week or so if they don’t get help.

Giant lasers are extremely expensive, even if you overcome the practicality issues, and we probably also want to kill the target right away, so lasers seem to be out. What about throwing bullets or missiles? Missiles are easy to shoot down because they’ve got that great big engine telling the whole star system where they are and they can’t spare the fuel to dodge that much. Plus they’re really expensive

Bullets are cheap, but they can’t move that fast and they can’t react to dodging targets or local gravity perturbations, so you’ve got to be REALLY close, or you’ve got to have a large, immobile target and a really big gun. In either case, you have to fire a LOT of bullets. Or there’s the option of dropping an asteroid on the enemy city.

The laser hitting the moon is no big deal. When it hits the moon, it’s a spot several feet in diameter. The reflection that comes back is scattered even more, but the detector is very sensitive. We’re not trying to blow up the moon.

When it comes to detection, active sensors (radar) have significantly less range than passive ones (IR). BUT, active systems require a LOT of power and passive systems require a lot of very expensive cooling and detector elements. Once again, engineering gets in the way.

Spotting planets is possible because of multiple years of intense observation of a very narrow segment of sky under near-ideal conditions, and with very specific detection parameters. We miss multi-mile asteroids all the time; many new ones have been discovered AFTER passing close to the Earth.

In some ways, spacecraft should be easier to spot, and in other ways they should be harder. Which wins? I don’t know enough to say; other than that engineering and circumstances will play a strong role.

So, due to the inaccuracies involved, it will be necessary to send warships to conduct precision bombing and invasions, and other spacecraft will be needed to fend off those craft. The difficulties to overcome are legion, but there will have to be a way for it to happen. Will it be like in games and movies? Probably not. But it WILL happen, you can be sure of that.

In terms of acceleration I was thinking of electric drives which have already been used on unmanned probes and not chemical drives.

You are right in this case. When talking about electrical drives, the acceleration is slower so the time becomes more important. But electrical drives haven’t been used in manned spacecraft yet. They are very weak and getting up to speed can take a lot of time. Their only advantage is that they are very energy- and mass-efficient. I guess it is conceivable to speculate about the technology becoming powerful enough to be used on manned spacecraft. However, the initial objection is valid for any kind of propulsion: intercepting an incoming spacecraft takes more energy than the intercepted spacecraft used for the entire flight.

A one degree change causes location change faster with more speed as the two tangents diverge from one another.

If you are working with degrees, the change of the position depends on the speed of the spacecraft. But so does the amount of energy you need for the same course change. At 10 meters per second, a 1° change is 10 times more energy expensive than at 1 meter per second. The only exception is when leaving the orbit of small bodies (planets, moons, etc.). In this case, the timing of the same burn can change the course dramatically. But this isn’t something you can use for mid-flight evasive maneuvers. For long-duration flights they remain prohibitively energy-expensive.

Putting a large enough lazer above our atmosphere to get the needed accuracy will not be as easy as you think and fixed orbital installations are the easiest targets of all to destroy.

A merchant ship can get away only if it knows where its attacker is and military ships invariably have better detection equipment.

Sorry, but this is getting silly. We have crossed the line of scientific speculation and deep in territory where we draw our experience from Sunday morning cartoons.

As for the lazer to the moon, most of the energy from the lazer did not return

Yes, it’s not a military laser. It’s a scientific one. The beam also passes the atmosphere twice. It’s doable with even modest equipment even today. I call this one closed.

The radar used on Apollo was tiny because larger wasn’t needed. In space with no obstructions or atmosphere a large radar would have a vastly increased range.

No it does not. Radar beams lose strength dramatically with distance. That’s why radar has a limited range even on earth. A radar with a range usable for space operations is not feasible. Otherwise, doing things like detecting coming asteroids would be easy. For detection of such objects, infrared is the way to go.

As far as telescopes are concerned, we can’t image planets out of our solar system.

Yes we can.

And remember, fuel reserves only increase the top speed. NOT the initial acceleration so the attacker can keep up with it and close on it for a time. Small course corrections in space are affected just as much by speed as they are time. Even at our current speeds, a slight course correction can leave a ship kilometers from its expected position in a matter of seconds

You are plain wrong in both cases. On chemical propulsion burns are short and acceleration time is negligible. As for course changes: you need to touch up you math. If you change your course by 1 meter per hour, after an hour you will end up 1 meter from where you would have been otherwise – no matter if you were standing still or going 30.000 km/h.

I do believe ships will be easy for other ships to find because we know where they are headed to and can intercept them just short of the destination.

Think again. A flight path is not just straight in space. You are doing orbits. For every starting point and end point there is an infinite number of solutions. Take a look at this “simple” flight from earth to mercury.

Currently a beam will slowly disburse over distance. We have no reason to believe this will be corrected in the near future even if we could make a beam strong enough to do significant damage on another planets surface. Even if it could, the techology to target something that far away will not concievably exist any time soon.

The reason for beam dispersion is mostly Eath’s atmosphere. Beam dispersion is a far less significant problem in space, where there is no air. Even with modest equipment we are able to shoot lasers at the moon, hit a small mirror installed there and receive the reflected beam. There was just no reason to try anything more ambitious yet. It is far less of a problem than propulsion.

Close range target reconnaissance would be needed to locate targets as our best telescopes can’t get that kind of resolution of a planets surface from long ranges.

This is true. I also assumed some kind of unmanned close range reconnaissance. On the other hand, keep in mind that the precision and resolution of our telescopes has increased at a dramatic rate during the last 50 years. Nowadays, we are able to spot planets orbiting other stars! Conversely our propulsion technology stagnated. If anything it deteriorated because it is simply too expensive.

Yes, radar in space already exists. Radar was even used on the “primitive” Apollo craft

This is true. However, the radar on Apollo was used to measure the altitude during the landing and the distance during docking. When it comes to doing a wide-area sweeps like on Earth, radar becomes ineffective in space. The distances are too great.

Yes ships will encounter each other in space. Military vessels will locate and interdict enemy shipping as they approach these sites but at a reasonable distance from the fixed sites defenses.

You didn’t really address any of my arguments there. For this singe maneuver, the military ship would need to use twice the energy the merchant ship used for the entire trip. The “merchant ship” could use that extra energy to simply get away. It quickly spirals away into a battle of fuel reserves rather than a battle of lasers like it does on the silver screen.

Radical manouvering won’t be needed because in space very slight changes and fluctuations in acceleration or deceleration will use no extra fuel and very slight course corrections will make a huge difference in ship location quickly.

Not exactly true. Like I said, evasive maneuvers cost fuel. This is OK for a single course correction. For a flight that takes months or even years, it’s not something you can afford permanently. For a ship to do evasive maneuvering, it would need to KNOW it is being targeted. In case of a beam weapon, it would get hit before it realized it was being fired at. Even if it did evasive maneuvers, they are far less effective than you might think. Small course correction can have a great impact in space but only because the trips are so long. Short-term course corrections are actually far less dramatic than what aircraft do. Astronauts hardly even feel the acceleration of their ships once they are in space.

As was pointed out, the distance in space is vast and a ship trying not to be seen when it’s already hard to find such things can best be seen and defended against at much closer ranges, in other words, from a space ship.

This assumes that the defending ship would be in the vicinity of the incoming ship. The chances for this to happen are extremely slim because space is so incredibly vast. The defending planet would need to have an enormous and quite expensive cloud of patrolling vessels. Again, a much more economic and reasonable approach is to use unmanned satellites and to shoot down incoming ships with space-based or ground-based energy weapons form afar.

Consider that even air battles don’t consist of dogfights anymore like they did in WWII. Most air battles today are about firing smart weapons at great distances. Or even simpler – using UAVs. This trend is even more likely to continue in space where there are much tighter constraints on fuel and weight.

But even this is a quite far-fetched scenario. That’s why I claim that of space battles won’t happen. It’s more likely for humanity to achieve eternal world-peace.