If surface abiogenesis is unlikely, panspermia is more unlikely because it needs the former, plus a way for the spores to survive in space, the travel of interplanetary, maybe interstellar distances, atmosphere re-entry and developement in a new environment.

Another factor is that, if we accept the current estimations for the age of Universe and the fact that some elements only are present in second or third generation star systems (because they were formed inside novas), we could be one of the first guests to the party. Panspermia would place abiogenesis even further in the past.

The only scenario in which panspermia would be more likely is that some components that are needed for life can only appear in space and develop on the surface.

That's not to say that panspermia is in itself an absurd idea, actually the fact that some elements need to be created inside stars means that we're somehow children of the stars, it just happens that panspermia isn't a great substitute for abiogenesis. An amplifier, maybe.

>> If surface abiogenesis is unlikely, panspermia is more unlikely because it needs the former, plus ...

That depends. Panspermia gets a huge multiplier from distributing the number of planets and eons on which abiogenesis might have happened just once. So it depends on the relative impacts of very different factors - neither of which have been well quantified.

If panspermia had ever been feasible, it was likely more so in the earlier universe. Personally, I prefer it because it seems to follow the Copernican Principle.

Well, that's... correct. I still think that it's less probable, but I have no way to prove it :)

If human equivalent creatures had taken just 10% longer to appear the sun would have dried up all the water on the earth and wiped its atmosphere before it happened.

Our star is unusual, as well over 90% of stars are smaller (and thus longer lived). Though if you go small enough you start dealing with planets in the habitable zone being tidally locked.

The increased likelihood of being tidally locked is not the only problem with smaller stars. As a rule, larger stars are more stable and smaller stars are more active. This is made worse by the fact that the habitable zone is closer to the star for smaller stars. Most stars in the universe probably can't support life as we know it because any planet close enough to be warm would get it's atmosphere stripped off by flares.

I'm talking about continuing evolution of the life that may already be there.

Informative points about stars.

for a civilisation with advanced rocketry and telescopes similar to what we have right now, it would still be very unlikely to observe us - firstly because we've only been around at all of a tiny fraction of the time the planet exists, and secondly because despite of all the ruckus we are currently causing in the planet, we'd still be very hard to observe from sufficiently far away

https://www.iaea.org/newscenter/news/meet-oklo-the-earths-tw...