It was the "how it would work" part that was key.

Small rockets are one thing, you shouldn't underestimate the challenge of building a Saturn V, it is an amazingly complex machine getting those huge engines to work, the fuel system and pumps, and making the whole thing fly without blowing up.

Take a modern turbofan engine. The basic concept isn't rocket science (no pun intended), but the actual development and application of it is harder than you might imagine.

Assuming that I took more than just myself, I don't think burning on a large stake would be a risk, we have automatic weapons. :)

That being said, your example proves my point, it would look like magic to those people who have no frame of reference.

We like to think we're smart today, but the reality is, we can't conceive of what 500 years from now will look like. We can guess, but we are likely to not just be wrong, but REALLY BADLY WRONG.

We may not even keep our bodies in 500 years, preferring to replace them with constructs with cybernetic brains. Most people I toss that idea to are horrified, including my mother and my wife, who think it sounds horrible. Which tells me that it might actually happen, but I really have no idea.

Math...

The number of planets, number of galaxies, and the size of the universe... if it doesn't exist, then there is something wrong with basic probability theory...

There are simply too many chances for it to exist for it not to. It just isn't likely to exist anywhere near us.

We would? You mean like we notice all those asteroids flying by that we get a few days notice of, or sometimes get notice of AFTER they have passed us?

What makes you think there is no stealth in space? Anyone who can come up with a FTL drive likely can come up with stealth in space.

How does it work? I haven't a clue, but I don't know how FTL works either, just like someone from 400 years ago couldn't tell you how a modern turbofan engine works.

That is a good point, and near-earth objects such as asteroids and comets aren't actually trying to avoid being detected.

Could WWII RADAR detect a modern Stealth Bomber?

Why do we think anything we have could detect a starship that has its "stealth systems" on? (whatever they might be)

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

Imagine the US Military of today decided to invade Europe of Napoleon's era.

Would their "old" technology do them a lick of good when a thousand M1 tanks rolled across the field at them? What about when Predator drones are flying overhead launching missiles at their supply depots behind the lines?

Perhaps their bow and arrows will be effective against the modern artillery and mortars of modern warfare?

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Instead perhaps we are "closer" to the aliens, so lets move forward to World War I, it is 1916, armies in Europe are locked on the Western Front, unable to make any headway either way.

The modern US military shows up with all the above items...

How long would the Germans last?

Reverse the roles, modern 21st century German army is transported back to 1916, how long would the British and French have lasted against the Leopard II tanks and Tornado fighter-bombers?

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It is silly to think that anything that we have would do anything at all to a civilization able to travel the stars.

Of course, which is why our Sci-Fi shows are fun, but at the end of the day, silly...

Take Star Trek... 400 years from now, I highly doubt we'll be walking around talking to the ship, we'll be interfaced directly with it and with each other...

But that doesn't make sense to your average person today and it doesn't make for great television, so they show "future versions of today", rather than the complete change that would really happen.

Go back 400 years, what were most people doing? Heck, most people couldn't read and write, most simply spent 90% of their time working to obtain food.

Try to explain 21st century life with the Internet, Space Stations, and Nuclear Weapons, to someone from that time. You'd be wasting your time.

Source?

I'd be shocked if we didn't find life in the oceans of Jupiter's moons, if we ever bothered to go there.

We have found life on Earth in places once thought impossible to support it.

I suspect the Universe is full of life, we can't can't see it from here and some of it we wouldn't be looking for until we ran over it.

Why use weapons? Why not just put the population to sleep? A modern tazer is a police officer's tool to subdue someone without shooting them, but it is crude in practice. Advance that idea 100 years and I imagine we'll have something closer to the stun rods from Demolition Man, just touch someone and they are put nicely to sleep. Advance it further and you could probably hit a whole city with a "go to sleep ray".

Weapons are crude instruments.

Why? Why is it unlikely? We have really no idea how to travel faster than light, like so many things, I suspect it is something we haven't even thought of... like how silly airplanes looked, until they actually flew and pretty fast they didn't look anything like the silly 19th century attempts to fly.

What was missing was power, lots of power, in a lightweight package.

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.

Nonsense, sure it does...

I am quite sure that if you went back 500 years and took modern technology with you, it would look quite "godlike" to those people.

For one thing, the planets are in one place, stay in one place (well, in orbit) for a long time, they aren't trying to avoid detection, and they are really big. They also have an effect on something even bigger that is its own light source, a star.

Starships fit none of those parameters. Even more, we aren't even looking for starships and if we were, we don't know what to look for. We DO know what to look for when it comes to stars and planets.

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! :)

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?

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.

I suspect the market isn't there yet for 4 TB SSD drives... and it wouldn't require a 3.5" drive case, you could fit 4 TB of NAND easily in a 2.5" drive case (or even less).

That said, the number of people who want to pay $2,000 for such a drive are still quite limited. Give it time...

Most modern SSDs have power loss protection. If it was that easy to lose all your data, no one would be using these things.

I've had power failures, and computers lock up, no data lost...