On 17/08/2017 12:51, Gary Harnagel wrote:
On Wednesday, August 16, 2017 at 8:42:58 AM UTC-6, Chris L Peterson wrote:

On Wed, 16 Aug 2017 10:00:23 -0400, Davoud wrote:

Quadibloc:

At least, so this news story suggests...

Nope. If they're technologically advanced they are looking for us using
the same techniques we are using to look for them. Their chances of
finding a tiny spacecraft in a vast galaxy are vanishingly small. And
they are governed by general relativity and thermodynamics. They will
never travel to Earth and we will never travel to them.

What I'd say is that they would be so close that if they had the
capacity to make interstellar journeys, they'd already have been here.

Maybe they have, but why would they upset an inferior civilization by
boldly presenting themselves?

To restock their space ship with fresh provisions - much like the
mariners of old did when they encountered a habitable island.

I don't think there's any reason to think an advanced civilization
couldn't visit other stars. If you're culturally stable, what does it
matter if it takes thousands or tens of thousands of years?

Or a million years. The galaxy is 9 billion years old and planets are
plentiful. In fact, there's a 14-billion-year-old red dwarf a mere
150 lightyears away, and Proxima Centauri is known to have a planet in
the habitable zone. At 0.1c, a civilization could populate the galaxy
in a million years.

The fastest manmade object is the Juno probe we have managed managed a
whopping 0.000013c or a shade under 40km/s. Even so they should have
populated the galaxy inside about 10 billion years at least in the sense
of self replicating Von Neumann probes or similar.

https://en.wikipedia.org/wiki/Self-r...Neumann_probes

Chances are we haven't seen them because they are not there.

--
Regards,
Martin Brown