On 5/28/2018 5:30 AM, wrote:

How long do you believe an intelligent and inventive
species can exist?

Well, if we're any example, then I'd say, not all that long !

We're about to poison ourselves out of existence.

You might want to read Arthur Clarke's sci-fi book
"The Fountains of Paradise",
https://en.wikipedia.org/wiki/The_Fountains_of_Paradise

It describes "starglider" on pages 74, 82, 92 to 96.
Interesting ideas.

Interesting, but realize that science "fiction" is just that.

But Arthur Clarke worked in Science before he became
an author of fiction.

At a minimum, go to a library and get the book,
and read pages 72 to 74, 82 to 85, and 92 to 96.
The pages about "Starglider" are certainly fiction,
but they very well describe the issue you talked
about in your original post.

"Contact" and "interaction" may indeed be possible,
even if the distances and possible speed may make
face to face meetings impossible.