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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?
The question isn't stupid, just asking it focuses attention on the fact that there are likely aliens out there.
Perhaps we should stop fighting each other on this planet and develop a real space transportation system?
While that is a nice hopeful story, and while I suppose ANYTHING is possible...
It isn't very probable...
Besides, even if they were at our level of technology, if they have starships, then they have nuclear weapons. They don't have to invade, they can simple drop rocks or nukes on us to accomplish the same thing, and there wouldn't be anything we could do about it...
Unless of course, someone had a Mac laptop and was a cable repair man! :)
Just because the hypothetical aliens are ahead of us in some respects (e.g. the ability to practically travel across interstellar distances) it does not necessarily follow that they would be ahead of us in all others.
Uh, yes, it absolutely does. If they have mastered interstellar travel, then then there is no way that they will be behind us in any other aspect.
On the positive side, this also probably means that they'd have nothing to gain by coming here or killing us off.
The better analogy would be near-earth objects. Even still, they stay in (sort of) fixed orbits, generally close to the orbital plane of the planets, and don't try to avoid detection. Yet we're nonetheless pretty terrible at detecting "ship-sized" NEOs. If by "ship-sized" one means "aircraft carrier-sized", odds are better than not that it wouldn't be spotted until it was within the orbit of the moon. If we're talking "space shuttle sized", it probably wouldn't be spotted until it got near LEO.
We gotta go to a crappy town where I'm a hero.
But a space-jumping fleet of invading space aliens is? Did you even read the summary?
Actually, it is very probable indeed... just not HERE!
Space is big, really big, unbelievably big... Odds are, somewhere out there, "space-jumping fleet of invading space aliens" DOES exist. Odds of them being ANYWHERE NEAR HERE? Almost zero.
Two separate points. :D
If physics doesn't allow for it, it doesn't allow for it anywhere. It doesn't matter how large the Universe happens to be.
It's a cute concept, but the simple fact is, if you have some simple technology for gravity control that can take a primitive society whizzing around the cosmos, then that primitive society wouldn't be using flintlocks for battle. Because if you control gravity to the point that you can hop some primitive ship in and out of gravity wells and move at relativistic speeds then you're controlling *vast* amounts of energy to do so. And there's no way such a species is going to only make use of this vast amount of energy in their spaceships but not their weapons - even if they're only kinetic impactors.
We gotta go to a crappy town where I'm a hero.
people in 1903 couldn't have dreamed of what the Saturn V would look like or how it would work.
Funny that you chose 1903 as your date, since that was the year Tsiolkovsky published The Exploration of Cosmic Space by Means of Reaction Devices, wherein among other things were mentioned that escape velocity could be achieved with a multistage rocket fueled by liquid oxygen and liquid hydrogen.
So yes, at least one person in 1903 not only could have dreamt, but did dream and explicitly state how rockets like the Saturn V would look and work.
"Total destruction the only solution" - Bob Marley
No, that doesn't make any sense, and I'd like a citation to that theory. Something is stealthed if you don't see it. To not see it requires no more than not looking at it. It is certainly allowable by the laws of physics that we don't look at something.
In fact, to suggest an old theory that says stealth of any kind is impossible not only imagines a theory that doesn't exist, but it violates the very principles of empiricism, thereby undermining the entirety of Physics with every other science to follow.
Even once we had airplanes, you have only a lifetime from 1903 to 1969, yet people in 1903 couldn't have dreamed of what the Saturn V would look like or how it would work.
In 1969 there were people still alive who were born in 1860.
Even one who was born in 1858.
Granted only a couple were in the US (and the recorded 1858 individual was in the UK).
But it is so freaking cool, that in their lifetime humanity saw:
-the first transcontinental railroad and mass adoption of trains globally (1863)
-the American Civil War, and other wars around the world
-the height of the Age of Sail, and then its end
-the rise of the steamship
-the rise of the automobile
-the rise of the airplane
-the shrinking of the world, and the end of the blank spaces on the map
-the rise of nuclear energy
-the rise of the League of Nations, and then the United Nations and the first real attempts at global diplomacy in place of war (and a reduction in large scale conflict; albeit with a shift to the Cold War)
-the emergence of computers
-and finally yes, the Saturn V rocket, and a man landing on the moon
That is so FREAKING COOL, all that happened in those persons' lifetimes.
The guy who said the election was rigged won the presidency with the second-most votes.
There was a time in the development of the universe where space and time itself essesntially expanded faster than the speed of light. It is pretty widely accepted physics. But this inflationary period after the big bang wasn't technically "faster" than light travel, because the definition of "faster" was bound up in the expansion of space and time. (If the space-time I am standing in expands, am I "moving"?) So, there is a physical process where matter and energy do something like faster than light travel, but not really. I imagine we could better understand this inflationary process and exploit it in the future to do something that isn't technically "travel". Many things that have been impossible in the past are now possible (space travel). But many things that were impossible in the past remaln impossible (FTL travel). We don't know what the future science will be. So it is best to keep an open mind and not assume anything one way or another, with a bias towards "I won't believe your claims until you demonstrate them to skeptical physicists who subsequently change their minds. Currently, no reputable physicist believes inflation makes faster than light travel possible.Experimental results, or it didn't happen."
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