Do you guys think humanity stands a chance against an alien invasion?

[Imran Khan]

it will be better if aleans wipe out this stupid race of humans

 

[Zarvan]

I'm going to assume that an alien invasion force is going to be carbon based and evolved in some sort of non-corrosive atmosphere, uses liquid water and have a 100-200 year lead in technology on us. That probably means they have quantum computers, extensive networking, railguns, lasers, nukes, fusion, hibernation and maybe the ability to build large (1 km+ in length) spacecraft in orbit, but maybe only be able to achieve 0.1% lightspeed (which is thousands of times faster than we can go right now and far greater than galactic escape velocity).

Their objective is to take earth for habitation. This means that they need to preserve, at the minimum, liquid water, an oxygen atmosphere and minimal biomass. They are a colonizing fleet of 100 ships filled with the last billion refugees of their race in hibernation or as frozen embryos with most of the ships functions taken care of by robots.

We observe their engine exhaust from its IR signal at 2 lightyears away. They arrive in 20 years or so.

Do we stand a chance?

Hell No only chance is if they are equal when it comes to mental capacity and very few in number.

 

[911]

Engines have to fire to slow down

The premise is an alien ship that is one kilometer long traveling at 0.1 light-speed and it is two light-years from Earth.

If the aliens don't want to fly by Earth at 0.1 light-speed, the one kilometer spaceship had better aim its engines at Earth and start firing to decelerate.

Since we do not see an alien ship decelerating in the infrared spectrum, we don't have to worry about it. By the way, you can't miss a one-kilometer long spaceship firing its nuclear engines in a hurry to decelerate. It will require a massive amount of energy and time to slow a one-kilometer long mass from 0.1 light-speed to zero meter per second.

Exactly what i thought.

 

[Hamartia Antidote]

Engines have to fire to slow down

The premise is an alien ship that is one kilometer long traveling at 0.1 light-speed and it is two light-years from Earth.

If the aliens don't want to fly by Earth at 0.1 light-speed, the one kilometer spaceship had better aim its engines at Earth and start firing to decelerate.

Since we do not see an alien ship decelerating in the infrared spectrum, we don't have to worry about it. By the way, you can't miss a one-kilometer long spaceship firing its nuclear engines in a hurry to decelerate. It will require a massive amount of energy and time to slow a one-kilometer long mass from 0.1 light-speed to zero meter per second.

I don't think the engine has to be the "pusher" type. A warp-type engine simply bends space. You don't really have to put on reverse thrusters.

 

[FairAndUnbiased]

I don't think the engine has to be the "pusher" type. A warp-type engine simply bends space. You don't really have to put on reverse thrusters.

I tried to make this physically realistic i.e. obeying the laws of physics within a 21st century context. AI controlled drones, artificial hybernation and fusion isn't too far out for us to imagine but bending spacetime is a technology if it existed, would be indistinguishable from a natural phenomena.

 

[CrazyRaju]

As long as ZH can wage a war with his white horse brigade there is no chance for the aliens to survive war with earthlings

 

[Jungibaaz]

It's okay, as long as we have Will Smith to save us (see Independence Day). I mean even if the aliens were 5,000 years more advanced, we'd be fine. Imagine humanity today vs 5,000 years ago.

 

[WAJsal]

It's okay, as long as we have Will Smith to save us (see Independence Day). I mean even if the aliens were 5,000 years more advanced, we'd be fine. Imagine humanity today vs 5,000 years ago.

We don't have to worry, as they usually seem to attack the US first, by then we'll be prepared for anything...

 

[911]

At 0.1% of lightspeed it will take 14000 years to reach earth from the 'nearest' earth like planet which could have life.

 

[CriticalThinker02]

You have a problem with the Type 2 and Type 3 civilization categories. They are fictional.

The known laws of physics state that nothing can move faster than the speed of light. Einstein's Theory of Relativity has been proven over and over again. It is a law of our universe.

Hence, Star Trek warp drives are fictional. So is Star Wars hyperspace jumps.

In the real world, things are mundane and boring.

To the best of our knowledge, with the best space telescopes observing the full electromagnetic spectrum, there is nothing artificial within 1,000 light years of Earth.

Hubble is looking in visible wavelength and near-infrared.
Chandra is looking in X-rays.
Fermi is looking in Gamma rays.

Herschel looked in far-infrared and it found nothing. Sorry, no alien spaceship.

References:

Chandra X-ray Observatory | NASA
Fermi Large Area Telescope
ESA Science & Technology: Herschel

There are ways to travel faster than the speed of light and some objects like galaxies do travel faster because the space around them is expanding, for example take a pencil and point it at one point on a piece of paper, there are essentially three distinct different ways for that pencil to travel across that paper, first is of-course taking your pencil and traveling it across the paper, second way is to grab the paper itself and pull it backwards while keeping your pencil stationary, third is it grab two points of the paper and literally folding it so that both the points meet.

In all the three scenarios you have traveled distance but only the first one is dependent on E=MC^2, objects not able to travel faster then the speed of light, in all the other scenarios it is possible.

If we develop a spaceship that takes the space in-front of it and pushes it back you can travel many times faster than the speed of light and this is not a theory, it's a fact and can be done because galaxies within our own universe are traveling away from each other faster than the speed of light because of the expansion of space in between them.

Maybe through the manipulation of gravity this can be achieved because gravity can bend space time etc.

The third scenario can be considered a wormhole of some kind.

 

[FairAndUnbiased]

At 0.1% of lightspeed it will take 14000 years to reach earth from the 'nearest' earth like planet which could have life.

won't be a problem for robots and frozen embryos. well, much less of a problem than for active biologicals.

 

[damm1t]

I would join them.. sorry guys

 

[mb444]

Forget aliens I doubt humanity will survive humans

 

[The Sandman]

lel there is no need for invasion from aliens we would destroy each other before that

 

[NP-complete]

Of course not. Take the example of atomic bomb. If Napoleon had the A-bomb, actually lots of them, whole Europe would have surrendered to him. Whatever army any european nation sent to the battle would have been annihilated. Any city that resisted would have met the same fate. All european nations would have become subservient to him and he would have ruled the world through them. I mean they would capture the whole world in his name. In this case Napoleon is obtaining a technology 150 years ahead of his time. Aliens would also come with a technology with a similar magical effect.
As we are divided in nations. Every nation will think of its own interest. Americans will contact the aliens and strike a deal with them. They will agree to work for them for their own survival. When the aliens arrive the americans will support them in capturing the planet.