Imagine a civilization on a dying planet a few solar systems away.
They have figured out that sending any multi-cellular soft tissue organism outside a light-year or so away is a waste of time. No way to shield adequately from cosmic rays and all suspended animation efforts eventually yield to entropy.
But self-replicating molecules of a very primitive sort can survive journeys across galaxies...crash the craft, release the 'seeds', add water & light & carbon and wait...a billion years or so perhaps but eventually an arc of inevitability will lead to opposable thumbs, language, greatly expanded cranial capacity, civilization.
Lather, rinse, repeat.

Fair enough, so let me qualify- I am only speculating on how life might have originally begun on this planet.
I think this needs to be addressed. Now I am 64 years old and I have vivid memories of films in school that had scientists attempting to recreate the early earth atmosphere. Loading the dice so to speak with super-saturated concentrations of amino acids and then shooting electricity or using chemical reactions to induce some evidence of any self-replicating molecule.
These experiments have been ongoing for a hundred years and so far...bupkis. No matter how much they cheat they cannot produce "life" in a test tube. It should be humbling and yet they continue to say they are getting closer to the elusive goal, just wait...
Now I am as confirmed an atheist as any, but at some point you have to examine the possibility that self-replicating molecules did not arise on early earth at all.

@3 Are you sure you're not mistaking the results of the famous Miller–Urey experiment, which did, in fact, create life in a test tube with nothing but elements available at the time life formed on Earth?
https://en.wikipedia.org/wiki/Miller%E2%80%93Urey_experiment
I think I remember a footnote about it not being taught in many schools because Jesus but I can't find any references to that.

It's a little sad to think but I expect our race—if not all life on Earth—will come and go before we ever find evidence of an intelligent extra-terrestrial species. Not because there aren't any, of course there are, or have been, or will be, but because our timeline is 1/100,000,000,000 of a blink of an eye on a cosmic scale.

@myself: Before the wave of pedantry, the Miller–Urey experiment produced amino acids, the building blocks of life.

@3

Even with loaded dice your odds on a laboratory bench are many, many orders of magnitude lower than what you'd calculate for an entire planetary surface's worth of chemicals interacting for on the order of hundreds of millions of years.

And though it doesn't get a lot of press, the lab guys have done some mildly frightening things with RNA synthase in recent years:

https://www.youtube.com/watch?v=QJ2yKuFeKjA (talk begins at around 14min)

Not nearly spontaneous cell formation, of course, but ever since interest in abiogenesis picked up again (after a lull of a few decades) things have moved well beyond that experiment that made the cover of Time Magazine when you were younger.

We've got the "RNA World Hypothesis" gang with their lab results, we've got the "Metabolism First" crew with their hydrothermal vents and proton gradients... they're often contradictory, and nobody pretends to have a full story, but all told the people working on the problem for the past couple decades have managed to gather together appeciably more than "bupkis".

well I looked at your link but I don't see where by any definition they created 'life in a test tube'... amino acids and enzymes and complex proteins are wonderful things but let me know when they have achieved a true sustainable self-replicating organism.
All these years in all those laboratories with all those precursors to manipulate and still no success. So I think it is reasonable to speculate that life originated under different conditions than obtained under early-earth conditions.

Check out the brilliant docudrama "Mission to Mars,"
directed by Brian De Palma, with Tim Robbins, Gary Sinise,
Don Cheadle, Connie Nielsen. It'll setchya straight.

@4,5 I'd heard of the experiment growing up (on TV and I think in biology class), so I'm not exactly sure it was repressed or anything. Problem is, while we can get to amino acids, it's still a huge leap from there to anything self replicating. It's a first step, but there's a lot we're still missing.

Which leads me to @1's point. I personally think that, the one, single most important thing we humans can do is to spread life as far as we possibly can. I am very skeptical that places like Mars or Titan or Europa or anywhere else in our solar system hold life. But perhaps they could. We could be seeding planets from Venus to Triton with bacteria. If we ever reach another star with suitable planets or moons, we should be seeding those too.

Humanity won't live forever. But no other creature before us has had the ability to reach out beyond the Earth before. We may not find life on other worlds, but it could well be the lasting monument to our own existence.

6- I concede I am not up on the current status of the science regarding creating 'life' in the laboratory or state-of-the-art early-earth modeling, hence my opinions are probably out of date. It is a fascinating but complex subject that I can only do violence to.

They may be closer to solving the origin-of-life question than I appreciate.
And perhaps all life in the Universe arises organically in place and panspermia is a bankrupt, crackpot idea.
Still- as a red-blooded American male I want to send my probes forth loaded with sperm to seed all the planets, moons, comets and rocks out there.

@4 thank you for pointing out that infinite space must be divided by infinite time when calculating for life. It's not just distance but time span too. Concurrency reduces probability.

@7 Honestly, that's how I remembered it, but in the years since (from reading the wiki entry) "life" isn't quite right. I want to say "close enough", but... yeah.

@12 Well put.