It is important to keep in mind how much technology is needed for interstellar travel. If we wanted to badly enough, we would be capable of interstellar travel with our current technology. The main technological hurdle is not any propulsion technology but perfecting the technique of maintaining a self-contained artificial ecosystem for an extended period of time-probably with a nuclear reactor providing power to lights that would maintain photosynthesis. The simplest and most reliable propulsion technology would be a solar sail, basically a huge sheet of aluminized mylar reinforced with composite fibers. It would look a lot like a parachute, but with a canopy multiple kilometers across and the ship being towed behind it. The acceleration produced is fairly weak, but it doesn't require reaction mass or energy from the ship to be generated for thrust. The ship can be turned around as it approached its destination and the solar sail would become a solar parachute decelerating the ship as it approached the new star. Depending on the length of the journey the ship might host multiple generations of passengers. Various types of nuclear fired rockets are the next most likely type of propulsion, but face the hurdle of requiring an enormous amount of energy and reaction mass to power them. Everything else is basically Star Trek-style fantasy at this point. However our understanding of physics and especially quantum physics is in its infancy.  

Ok , this alien race finally received the broadcast transmission of Mars Attacks and it pissed them off. Say their homeworld was two to three times the size of Earth. Would their evolution in a heavier gravity allow them to pick up say an M1 and toss it like a horseshoe?

Also, how long would it take us to adapt some of their weapons for our own use. If it was an invasion or say subjigation rather, they would have to send ground forces and there will be instances where we will be able to get our hands on some of their gear. As in the previous example of the roman army versus a modern army, there will be instances where the romans get some of the rifles and such.

The problem with fighting an alien invasion is that space is the "high ground" compared to the surface of the planet.  Since they already have the high ground, we are at a severe disadvantage.  Think about that scene in The Rock where the bad guys who took over the prison have the good guys bottled up in a shower room.  The two forces were exactly equal.  The roughly the same number of men who had the same training and were using the same weapons.  The only difference was their position relative to each other.  Throughout history no one has ever made a habit out of "taking the low ground."

 

Aside from the position imbalance, an alien force has several more advantages.  They have more room to maneuver, they probably have the advantage of suprise (don't notice them coming), they have better information security because they can see what we're doing but we can't see what they're doing, etc.  They also have the technological advantages which are obvious.

 

The problem with trying to strategize about how to beat this hypothetical force is that we not only have no idea what their motivation would be, we have no idea what their physical structure is.  There isn't a law of nature that says aliens have to be just like us.  They could be made out of energy and have evolved in the vacume of space, never having "set foot" on a planet before.  If that was the case, would they even recognize us as life?  If they are physical, they might not be carbon based.  If they are carbon based they might not think the same way we do, etc.  How do you plan to fight anything?

 

The only way this discussion works is if you lay down restrictive ground rules.  You have to specify things like the alien's physical structure, their motivations, their technology, etc. 

 

But back to the actual question which started this: your question is moot.  If I was trying to defeat a planet-based military I would just drop things on them.  I mean, where are they going to go?  It would be like shooting fish in a barrel.  I wouldn't put my own people down on the surface to get shot at by the natives, I would send down robots to clean out the inevitable concentrations of natives who hid in caves and things where my kinietic energy weapons couldn't reach them.

If aliens show up some dumb humans are going to start worshiping them.  then they can hire others like the British worked with the untouchables in India.  The fight would (if there were one worth noting) be humans fighting humans with aliens throwing some suport to their friends a critical times.  If the aliens could move back and forth from orbit easly they might concor the planet with a platoon of infantry. 

 

The aliens might just show up to sell us trinkets.  They get all the advantages of the planet with out having to mess it up.

 

 

 

 

It is a tough question. The cultural high ground is a lot more devastating than the military high ground. If aliens showed up tomorrow and asked the leaders of your government if they wanted to sign a treaty in exchange for fantastically advanced technology, or else they could go talk to someone else, what should they say? Of course they have to say yes, they have no choice because they know that sooner or later some nation will say yes and that nation will then have an enormous advantage over them. And so we have the beginning of the scenario that occurred during the European colonization of the Earth being conducted on an interstellar scale.

 

This begs the question though, if all of these terrible things--from military attack to cultural domination--could happen if an alien race were to come to earth, what could we deduce about that race's motives if they behaved in the ways that UFOs are purported to behave?

theory for you.

seeing as ufos are supposed to accelerate at silly rates and vanish , turn right angle corners etc#maybe they arent doing it at all. maybe its an ECM system

false target generation, -but with light

you want a quandary for our political leaders how's this one.  the aliens show up and will swap uber new technology across a broad spectrum in exchange for the tastiest 3% of your citizens.  of course if you aren't interested there are other parties willing to trade but we think you have the tastiest humans so we're gonna give you first shot at the trade.

Been there, done that -  "How to Serve Man"  - Rod Serling, Twilight Zone episode circa 1960ish.

 

swhitebull - I prefer "V"  or "Independence Day" efforts. The moral question is -  How do you select those 3%, and who does the selecting? Fat-marbled steak is ALWAYS the best tasting cut, so do you want to go for the BBWs?  

you want a quandary for our political leaders how's this one.  the aliens show up and will swap uber new technology across a broad spectrum in exchange for the tastiest 3% of your citizens.  of course if you aren't interested there are other parties willing to trade but we think you have the tastiest humans so we're gonna give you first shot at the trade.

In Canada's case it would be simple. Parlez vous Francais?  MMMM A-1 steaksauce.

Herald

two problems come to mind with that.  first off there are a lot more than 3% of the total pop'n being quebecers and somehow i can see those not chosen feeling just a tad put upon.  also given how the politics here works the liberal party surely isn't going to want to upset the quebec applecart they need to stay in power.

torontonians while no one would miss them get a pass on this for being such a sour lot but i can see the liberals cheerfully sacrificing albertans for the greater good.

obviously as a good socialist you take the high earning non donors to the cause which frees up their property to be divided among the true believers

bbw's gah be like chopping lard hogs for meat ie a waste of time.

 

i suppose you could just ask the aliens for their definition of tasty and work off that.

 

it's national grouch day which is of course a monday.