Aliens visited Earth, took one look and left, hurriedly ...

[dogtag]

They echoed Bette Davis' famous words "What a Dump"

https://www.the-sun.com/news/4238103/aliens-may-have-visited-earth-nasa-report/

[togor]

Cameras everywhere now yet the sightings don't really get more convincing do they.

[dryheat]

Since private companies are doing a lot of their work I guess they have more time on their hands for fun stuff.

[Vern Humphrey]

There's a simple Einsteinian thought experiment you can apply. The only way we can detect life OUTSIDE our solar system is by their radio signals -- they don't make a telescope that will let us see microbes on a planet 100 light years away. So we can only detect a high-tech civilization that communicates in the electro-magnetic spectrum.

Now imagine a sphere in space, say with a radius of 100 light years, with our solar system at the center. Imagine there is one other high-tech civilization like ours somewhere in this sphere.

Now double the radius of the sphere. The larger sphere has 8 times the volume of the smaller sphere. If there are TWO high-tech civilizations in the smaller sphere, there should be something like 16 high-tech civilizations in the larger sphere.

If there are 15 other high-tech civilizations within 200 light years of us, it is inconceiveable that we have not detected at least one of them already.

You can make the first sphere as big as you like -- the argument still holds.

[togor]

Vern how long has humanity been producing radio waves at a detectable intensity?

[lyman]

we are, IIRC, towards the edge of one of the spiral arms of the Milky Way

there are other Galaxies that we know off,

to suggest we are alll alone in the universe, is a bit self centered,

little green men in space suits flying around in saucers,, likely not,

but some type of life, somewhere out there, likely yes

[togor]

Agreed.

Whether we can directly interact with it is another matter.

Physics demonstrates that the speed of light in free space represents an upper limit for how quickly information travels. Even gravity waves, as detected by the LIGO experiment, propagate at the same velocity as electromagnetic energy.

Enthusiasts assume that the aliens figured out ways to outsmart nature with their fancy UFOs, but that's a lot easier to fake than to actually pull off.

[dryheat]

We are in agreement. There's no way there isn't some kind of life out there, but it's a loong way away.

[Vern Humphrey]

Given the time scale of the universe, how likely is it that WE are the first to develop radio?

We've been using radio seriously for about 110 years or more -- the Titanic sent an SOS message in 1912, and there was considerable radio traffic between the Carpathian (the ship with the survivors on board) and New York. So any high-tech civilization within 100 light years should have heard us.

More importantly, we should have heard THEM. We should have heard a civilization a thousand light years away if they have been broadcasting for a thousand years.

[dogtag]

There maybe microbes out there somewhere but they're hard to communicate with.
As for intelligent life - it takes a virtual miracle for everything necessary to come
together and cause this to happen. No matter how big the Universe is it could
still make us totally unique. Or it may be that we are the first to develop.
Somebody has to be first.

[pcox]

There are no aliens, if there was we would have sent them foreign aid by now.

[lyman]

There are no aliens, if there was we would have sent them foreign aid by now.

[Vern Humphrey]

There maybe microbes out there somewhere but they're hard to communicate with.
As for intelligent life - it takes a virtual miracle for everything necessary to come
together and cause this to happen. No matter how big the Universe is it could
still make us totally unique. Or it may be that we are the first to develop.
Somebody has to be first.

Exactly the point. The more likely a given life form, the harder it is to detect. There may be microbes on a planet a thousand light years away, but how will we ever find them?

On the other hand, it there are high tech civilizations out there, we should have detected them long ago.

[dogtag]

So, if we suddenly discover an Alien civilization 100 light years away,
how do we get to meet or maybe trade with them ?
Assuming they're stuck with the same problem we have in that
nothing with mass can approach light speed, it makes the idea moot.

[lyman]

So, if we suddenly discover an Alien civilization 100 light years away,
how do we get to meet or maybe trade with them ?
Assuming they're stuck with the same problem we have in that
nothing with mass can approach light speed, it makes the idea moot.

yep,
we will have discovered their past, no idea what the present will be for them