> what makes you think that a drive system entails defense beams?<

Two general reasons.

The first is that it is almost inconceivable that a civilization could develop even STL, let alone FTL starships, without grasping the principle of the laser, and that the energy required for such travel, if but a small fraction of it were channelled into lasers, would be enough to power a laser-based missile defense system far more capable than anything the whole world could build today.

The second is that travel at high STL speeds requires some sort of forward protection if the ship is not to be eroded by impacts of interstellar gas and dust against her prow. Charged particle s and objects can be deflected by electromagnetic shielding, but for the ship to deal with neutral or nonmagnetic objects it has to turn them into ionic plasma; the best way to do this is with a powerful laser beam.

Now, the kind of sensor required to detect such dust particles in time to hit them with the beam would be highly capable; it would be a trivial modification of function to use such a keen sensor and powerful laser beam to defend a ship against anything as slow and clumsy as modern nuclear missiles would be by those standards.

In other words, the technology required for interstellar travel ensures that a race capable of doing so at speeds greater than a few percent of lightspeed with anything larger than very small and simple probes is also capable of defending themselves against our primitive military technology.

Think about a modern freighter. A modern steel-hulled freighter, with its tens of meters-high sides, is not a warship, but a freighter crew with a few rifles could defend those sides against while sinking by ramming the most powerful war fleets of the Classical world. Likewise, even an "unarmed" starship would have far greater combat potential than the most powerful air and missile forces we could bring to bear today.

> okay, say its so. Now we have superlaser warfare.<

It has to be so unless the technology of the ship has pursued a very different path from our own. Which is of course a possibility. But a very low-probability one that the path is both effective enough to allow interstellar travel but not capable of producing some awesomely powerful weapons effects even with civilian technology.

> The USA also has ground based superlaser warfare. <

We do? Since when?

In terms of what we actually have today in terms of lasers today, what we have are half a dozen to a dozen Airbornee Laser Systems, which are limited to a dozen or so shots each and have no particular ability to hit anything above Low Earth Orbit. And the energy output is pitiful by the standards of the wattage required for interstellar travel.

> So unless the ship has shields, we can still hit it hard enough to knock out its guns. <

First of all, the ship very well might have "shields" -- it could manipulate charged dust particles in its own electromagnetic force fields (which it would need to screen itself against the speed of its own travel) so as to create a renewing barrier which would ablatively absorb laser energies at the levels that we are currently able to generate them. Secondly, you are making the very big assumption that the ship's effective range against our relatively fragile materials is not considerably greater than our cannons' effective range against their centuries-more-advanced superalloys. Finally, you are ignoring the very strong possibility that the ship --- or, more to the point, its auxiliary craft -- would be far more maneuverable than our low-tech aircraft and spacecraft, and hence it could hit us at ranges that we could not hit it (owing to lightspeed lags).

> Plus, if the usa fires its full contingent of orbital missiles, thats no small number of objects to shoot
down. <

Our what? As far as I know, we have no missiles capable of engaging targets below extremely low Earth orbit. And you're massively underestimating the amount of time that these missiles would take to close -- the ship would have a _long_ time (by the standards of a beam laser engagement) to shoot said missiles down. Remember, our missiles would have to close within at _least_ few miles to detonate close enough to have much chance of damaging a ship designed to withstand the stresses of high sublight speeds. (Personally, I wouldn't give us much chance on anything but a direct hit).

> If we look at it tactically, its a rapidly loosing proposition for a space ship to come anywhere near the planet if they think we will open fire on them. <

Their concept of "near" and our concept of "near" might be different. In Classical naval warfare, "near" meant within 100 or so yards of your ship. In modern naval warfare, "near" means within five or so nautical miles (10 _thousand_ yards) of your ship. To them, "close range" would probably mean "within a LS" (300 thousand kilometers) -- more than half the distance from Earth to Luna!

If an alien ship parked itself 250,000 km from the Earth, it could (if it were hostile) rain down destruction on us and there is nothing we could do about it -- at that range none of our lasers would be strong enough to do it much damage, and our missiles would have flight times of _hours to days_ (assuming any had the range to reach it). You are greatly underestimating interstellar, and greatly overestimating our own, technology.

> first off, its not the quantity of power that does ftl. Thats really just primitive idiocy trying to solve the problem by overpowering it. Its the organizational level or the energy used that matters, not the quantity. <

And you don't think that a race with the ability to manipulate through engineering forces that we only dimly grasp theoretically (if at all) would also be able to use this technology to in various subtle ways protect themselves from harm? It's bad enough if they merely use the physics we already know with better engineering and greater wealth than we have -- if they also know _more_ physics then we do, our military capabilities against them would be even _less!_

> As far as gravitional force feilds go, okay, MAYBE. But what does a gravitional force feild actually accomplish,?? <

To take one obvious application, if one could master gravity _and_ had the kind of energies required for interstellar travel, one could power a tractor/repulsor or a force beam which could (as desired) stop missiles in their tracks or smash them to pieces. Or, for that matter, possibly reach down onto the Earth's surface and pick up or smash the batteries trying to engage your ship!

That's a big brute force obvious way of doing it. Several science fiction authors have pointed out that if one could master gravitics one could tune the beam to a particular mass-pattern (say the signature of an Airborne Laser System airplane) and apply far less energy to it at its resonant frequencies, shaking it to pieces with great efficiency.

Oh, and that could be done through armor. Even through miles of solid rock. In other words, if the aliens had _that_ technology they could do things like stop us from launching our missiles by vibrating the people trying to turn the launch keys to red jelly on the spot. Nice image?

Or, if they were more humane, they could simply cause the missiles to harmlessly fly apart in midspace, thoughtfully removing the warheads and directing any other fragments (via tractor beams) onto trajectories where they would impact harmlessly far from human habitations. That's even scarier, in a different way, if you think about it.

> The question is "why don't they visit.? " the answer is that we are barbaric and dangerous. I should think
that would be self evident in the first place, but to belabor the point seems bizzare to me. <

I think that you haven't though through the implications of a sufficiently superior technology. How threatened would a modern US Marine LAV platoon be by a village of Neolithic savages? Or even a Sumerian city-state? That's the kind of technological gap that would exist between us and interstellar aliens.

> Unless they tried to come here specifically, which is i think the main point of the conversation. <

Well, if they wanted to come here specficially, and they felt we were dangerous, they'd simply bring along _their_ equivalent of personal body armor and military weapons. Which would probably be on a scale that would let individual soldiers defeat whole Earth divisions, given the energy and tech differences.

Assuming that they wanted to land with sapients, which they wouldn't have to. They could land disposable communications drones with enough defenses to make sure that we would have to expend serious military efforts to destroy them, and keep sending them until we gave up or ran out of ammunition.

Mind you, that's assuming they're _not_ hostile. If they were hostile, the war would be simple. Zap zap zap, we lose. And if they were genocidal, we die.

> ------------
Thermonuclear warheads are pretty small stuff on the scale of interstellar warfare, anyway. Try relativistic kill vehicles (projectiles accelerated to near light speed), antimatter warheads (which could pack hundreds of times the energy of thermonuclear fission-fusion-fission in the same space), or x-ray to gamma-ray lasers (**). THAT is the sort of death a system-wide let alone interstellar civilization could deal out, if it was so inclined.
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sure, not to mention new inflationary bubbles, gravitometric bombs, and other solar system doomsday devices. <

Um, no, I didn't mention them because we don't know if they are theoretically possible (I said I would stick to real physics as much as I could). RKV's and high-frequency lasers are both things that we could theoretically build NOW if we tried; our models just wouldn't be very effective compared to what a system-wide civilization could construct.

New inflationary bubbles may or may not be possible. One version of the theory that allows their creation says that they form pocket universes which can only interact with ours through a wormhole neck if at all. I'm not sure what a "gravitometric" bomb is, but if you're talking about an artificial short-lived singularity, it's probably theoretically possible but we don't know how to do it, not even theoretically.

But yeah, an interstellar civilization, especially if FTL, might be able to play all sorts of nasty tricks like that on us, if they were so minded.

> So? Just because they could wipe us out doesn't mean that we couldn't wipe them out also if they came HERE. <

Um, no, that's exactly what it _does_ mean, unless the aliens for some bizarre reason only ever develop offensive weapons and NEVER develop any defensive weapons -- or never develop any weapons on scales OTHER than the cataclysmic.

As counterexample I give you Earth humans. We build megaton-range nuclear ICBM's, yes, but we also build every other size of missile down to personal firearms, and we also build defenses against the various sorts of offensive devices we construct. A bunch of 21st century humans in a freighter, faced with a potentially hostile Neolithic island people, would not be limited to either nuking the island or avoiding it -- they could choose to wear body armor and carry automatic rifles, if they really wanted to do things on that island and seriously feared native attack.

That's just in terms of "hard" technology, of course. Modern humans can and do use all sorts of "soft" technology (psychology and tactics) to overcome primitive humans and subhuman beasts without even fighting. An interstellar civilization would probably also have soft technology far in advance of our own.

> But i doubt you'd think of it that way if you were looking at an alien anthill and trying to decide whether or not to stick your finger in it to see if you'd get stung. <

Funny you should put it that way.

Protective suits capable of fending off theattacks of social insects is a technology we've had for a _very_ long time. Beekeepers use them when dealing with the more hazardous strains.

We also, of course, have Raid ...

> Compared to an interstellar civilization, we'd be like Australian aboriginies with spears and boomerangs against helicopter gunships and infantry fighting vehicles.
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true, but if this is just the aliens version of an unarmed transport vehicle like us driving around a CAR
instead of a TANK the truth is, we could be very dangerous to them... dangerous enough that its simply more sensible for them not to bother to come here. <

Actually, primtiive (pre European contact) Aboriginies would have a lot of problems dealing with a group of explorers in a car suitable for the Outback (which would be a large air-conditioned SUV or other All-Terrain Vehicle). For starters, they wouldn't be sure how to attack the vehicles -- _we_ with their weapons and skills would tell them "aim for the driver!" but they wouldn't automatically have the knowledge that this was its most vulnerable spot. They also wouldn't even automatically realize that parts such as the windows and tires were weak spots -- they might waste a lot of time smashing headlights or beating against the grille.

Modern humans going into a situation with potentially murderous natives would probably carry firearms. Maybe not full military weapons, but even a civilian hunting rifle or a decent pistol would be hideously effective against people armed with nothing better than spears, war clubs and boomerangs (and yes, I know that the Australian _war_ boomerang is a real missile weapon) and mostly protected by the metal parts of their vehicles. A wealth factor would also apply in that Aboriginal tribes, being pre-agricultural, were small -- it would not take very many dead or wounded Aboriginies to make the enemy tribe run away. And so on.

> (*) One of the likely means of FTL is the creation of wormhole pairs with spacelike paths, which implies a mastery of gravitics tech.
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sure, and if you can do that, you can end the solar system with a closed wormhole loop
or a new inflationary bubble.<

Or do smaller scale things like warp a volley of missiles heading towards you to a harmless location, for instance. That's my point -- FTL tech gives you a lot of means of defending yourself that are beyond not merely our technology but our _science_ as well, and many of them would be possible on many different orders of magnitude.

- Jordan