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Ask Slashdot: How Could We Actually Detect an Alien Invasion From Outer Space?
First time accepted submitter defiant.challenged writes As I was watching another sci-fi blockbuster about aliens wanting to harvest the life stock population on earth for their energy since we are such a robust species, I was wondering how likely and easy/difficult it would be currently to actually detect an outer space invasion (fleet). I am a firm believer that if we would be invaded, we would not stand a chance and would probably not even hit a single ship when it comes to fighting them. The aliens in the movie had the capability to space-jump right into our solar system and even very close to earth. My question is how good are we at the moment in detecting an alien ship/fleet that jumps into our solar system. Do we have radio dishes around the globe such that we can detect objects in space in all longitude and latitude degrees? I know we have dishes pointing to the skies but how far can they reach? Do we have blindspots perhaps on the poles? I also wonder if our current means, ie radio signals, are relatively easy to be compromised with our current stealth technology? To formulate it in more sci-fi terms, how large is our outer space detection grid, and what kind of time window can they give us?
Do you expect any other answer than "we would be fucked"?
Frankly, any aliens able to travel here from another world are so far ahead of us, it wouldn't make any difference if we detected them or not.
However, you asked the question... so...
Our space detection system is largely aimed at Earth. For example, to warn of us of ICBM launches the first system put into space was called MIDAS between 1960 and 1966.
http://en.wikipedia.org/wiki/M...
The GPS satellites have nuclear detonation detectors, which doesn't do any good, but it another example of how our systems are aimed at Earth.
All the stuff pointed out into space, like the Hubble Space Telescope, are designed to see VERY far away and aren't looking for ships. Given the small likely size of any ships compared to planets and moons, we aren't likely to be able to see them even if we're looking for them, until they are on top of us.
After all, we still don't have a telescope that can see the moon landing sights. Pictures taken from sats in lunar orbit have gotten some pictures, but they aren't as good as you'd expect.
http://en.wikipedia.org/wiki/T...
This is the best image I could find of Apollo 11's landing site, and this was after the LRO was moved into a lower orbit:
http://featured-sites.lroc.asu...
Yea, you can tell what it is, because you know what you're looking at, but if you didn't even know where to look? You could stare at the moon for a month with such a camera and see nothing.
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TL;DR - We likely would have no notice whatsoever of aliens until they entered orbit of Earth, and even then, it is just as likely to be a random person with a telescope who spots them as anyone from the government.
Unless of course they can be seen with the naked eye, if their ships are big enough and they are in low orbit, that is possible.
"It isn't very probable.."
But a space-jumping fleet of invading space aliens is? Did you even read the summary?
"National Security is the chief cause of national insecurity." - Celine's First Law
We have problems spotting and tracking 1km-long rocks in space beyond the Earth's orbit. We literally get taken by surprise by large rocks and their orbits all the time, whizzing around our solar system without us knowing they're there.
We're also not looking for those kinds of things, as such. A ship of some description able to sense us from afar and come into the system probably wouldn't jump in at the third planet out by default. They'd probably jump in off-axis, far away, and we'd be hard pushed to spot anything of space ship size (http://io9.com/nasa-spots-a-po...
That wasn't spotted for ages, discovered only in 2013, when it was only 10 times the moon's distance away (nearly a Mars distance). It was spotted only by something looking for near-earth objects and only because it looked like its natural trajectory may bring it close to Earth in the next 100 or so years. It's 650 metres long, orbits every three years and could weigh tens or hundreds of thousands of tons.
We can't see this kind of stuff. The angles and chances are just too small and anything that settles into a natural orbit is basically indistinguishable from a rock. It wouldn't take much for something to jump in just outside the outer planets and settle, say, a Saturn distance away, probably off-axis (hiding in-axis may well give shadows etc. that give it away and we likely look at the planets and other things in our axis more than elsewhere) and we'd never spot it. Never. If we did, we'd think it was a rock.
From there, a basic telescope (or a pair of binoculars) would be able to light us up like a Christmas tree, show us to be particularly interesting, and a simple radio antenna would be able to prove that their was life on here, while at the same time being basically invisible to us without even trying.
Any civilisation with a 1km intra-system space-ship capability likely has much better tech than a $200 telescope and a satellite dish connected to a radio scanner, They'd know we were here, and be able to observe us for centuries, long before we ever would know they were there - and we'd probably NOT know they were anything other than a rock.
The distances are too immense, the angles involved far too tiny once you get out past the moon, and there's just too much stuff moving about if you have a sensitive instrument. Hell, we don't even reliably know what everything in EARTH ORBIT is, let alone trying to go out to even a Moon-distance or Mars-distance or Neptune-distance.
Basically, we would never know. The only way to get to the point we would know would be to colonise enough of the solar systems to provide mapping and triangulation of the entire space in-between, And even then, you probably could still hide if you were at all careful.
http://en.wikipedia.org/wiki/Action_at_a_distance could be used as to communicate.
No it can't. Although entangled particles can interact, you cannot use the channel to communicate. Any "message" sent looks like random noise. It is only when you compare it after-the-fact that you can see the FTL influence.
It is like you have two perfect random number generators, and you can switch from one RNG to the other, and have the change happen instantly light years away. But on the other end, they just see a continuous stream of random numbers. If you can latter look at the stream of numbers, you can see that the switch happened at faster than light speed, but no useful information was communicated.
No, because the people at the end points can't control what they measure their entangled particles to be. There's no information transmitted in the process, all you get to do is:
1. Measure the entangled property, say, the spin, on Earth.
2. Be like: Wow, on Pluto that must've given <opposite property>.
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