Let's talk sentient and spacefaring life from another planet orbiting a distant start from us using the scale of the expanding observable universe.
1) Life could have begun, rose and fell billions of our solar years ago. Future exo-archaeologist dreams come true.
2) Life could have begun, rose and fell millions of our solar years ago. Future exo-archaeologist dreams come true.
3) Life could have begun, rose and fell thousands of our solar years ago. Future exo-archaeologist dreams come true.
That takes care of time scale issues.
1) Life could have begun, rose and stagnated in development.
2) Life could have begun and never rose to any development.
That takes care of technological development.
1) Life could have begun, rose and fell due to self-war.
2) Life could have begun, rose and fell due to disease.
3) Life could have begun, rose and fell due to natural disasters.
4) Life could have begun, rose and fell due to invasive species.
That takes care of internal and external factors.
1) Life could have begun, rose and thrive light years away.
2) Life could have begun, rose and thrive tens of light years away.
3) Life could have begun, rose and thrive hundreds of light years away.
4) Life could have begun, rose and thrive thousands of light years away.
5) Life could have begun, rose and thrive millions of light years away.
6) Life could have begun, rose and thrive billions of light years away.
That takes care of distance issues.
1) Life could have built generational ships to cross the expanse between stars and galaxies.
2) Life could have portal technology to connect the vast distances of galaxies and stars within them.
3) Life could have developed mental capabilities to explore the universe without leaving the home planet.
4) Life could have... imagination has no limits on possibilities.
That takes care of transportation issues.
These are real down-to-earth statements for explanation with how we understand physics and potential technology. The odds of a sentient lifeform, surviving technological process, leaving home system, and crossing vast distances to enter our solar system, land on our planet, and be present during our time on the planet for both species to meet. Very astronomical.
1) Life could be non-carbon based.
2) Life could be non-corporeal based.
3) Life could be non-linear based.
That takes care of recognition issues by humans.
1) Life may not be able to verbally communicate.
2) Life may not be able to translate communication.
3) life may not have limbs to visually communicate.
That takes care of conversation issues.
1) Life might not recognize humans as life.
2) Life might not recognize conditions on Earth as life.
That takes care of recognition issues by alien life.
The odds now have just skyrocketed ever so beyond astronomical.
1) Life might be benevolent.
2) Life might be warlike.
3) Life might be in need of new food sources.
4) Life might be in need of more natural resources.
That takes care of intention.
On the other hand, life is splendid among the stars cooperating or fighting and waiting for our arrival on the galactic stage.
3) L