I've heard on panspermia in relation to Earth.
But what are the odds an asteroid hitting Earth has already seeded life elsewhere in the solar system?
But what are the odds an asteroid hitting Earth has already seeded life elsewhere in the solar system?
Of course that likely doesn’t apply to life as we know it, assuming our estimates of the age of the sun and the universe are correct.
I wonder to what extent the scientists who study these evolutionary clocks are able to factor in increasingly (or decreasingly) capable DNA replication and repair mechanisms. More faithful DNA replication and repair would artificially show a slower rate of genome evolution.
It is hard to imagine life without a large variety of atoms.
Stars with rocky planets during the habitable epoch "lie ∼8.5 standard deviations (σ) away on the exponential tail of the Gaussian probability distribution of initial density perturbations," though "their abundance could have been significantly enhanced by primordial non-Gaussianity."
It sounds like there is a chance some atomic fusion could have occurred at this time, but It would be isolated to a few instances in our light cone. This is a pretty different than the entire universe awash in favorable conditions to life.
Our universe would seem to them like the universe on the verge of heat death does to us. To my knowledge, I don't know of any fiction that explores this setting--it's on my bucket list to write.
I read something by a SETI researcher that pointed out that some research focuses on finding DNA outside of earth (e.g. Mars) that has the reversed chirality of DNA on earth (i.e. corkscrews the opposite way of all life we've found on earth). This would be an incredibly strong indicator for life that actually came from somewhere else and wasn't just contaminated from DNA from earth that got on the equipment. They said "strong" instead of "certain" as it's still possible for a "shadow biome" on earth where the chirality is reversed that we just haven't found yet. This is important as there is no reason that it should be one way or the other (at least that scientists are currently aware of). As far as they can tell it should be 50:50, so chirality makes for an interesting indicator. Note: this is what I read over a decade ago. I'm no biologist.
Can you point to any source for that? I've never heard of such a thing and can't find anything from a quick online search supporting that idea. Everything I read is that gravity will pull back any bacteria that get to the outer edges of the atmosphere, which makes sense because they'd need to have some force stronger than gravity to escape.
What information can you point to that supports the idea that we leave a "plume of life behind us"?
I think the idea behind an asteroid is that only something with that level of force could eject bacteria that could overcome the Earth's gravity to escape.
Edit: atmospheric escape [1] is a well-known phenomenon, but that's exclusively about gases, at the molecular level. It doesn't mention anything about bacteria, which are of course massive in comparison -- the factors that can cause a single atom or molecule to gain enough energy to escape gravity don't apply to things the size of bacteria.
Relative to the center of the Earth (average gravity) , the atmosphere ends approximately at sea level.
Small particles aren't escaping based on their own velocity from random collisions. Maybe from interplanetary scraft like Voyager.
Impact erosion seems like it would have enough energy to eject microbes from the atmosphere given the amount of life in the troposphere [1].
[1] https://nautil.us/the-surprising-importance-of-stratospheric...
That's why helium escapes pretty fast. The other gas molecules still escape, but far far slower. The Maxwell Boltzmann distribution applies.
Something like a virus is far far heavier again, so the rate of escape would be miniscule. Not sure if it's small enough to have never happened across the surface of earth though.
The authors suggest/speculate about the existence of some ionospheric updraft or electromagnetic phenomenon capable of elevating them to the upper thermosphere where ISS is located. If that's true, panspermia hypothesis suddenly becomes much less far-fetched, and also the "reverse panspermia" you're talking about.
https://www.hindawi.com/journals/tswj/2018/7360147/ - one of the papers related to the experiment
https://nplus1.ru/material/2020/02/21/iss-test-experiment - a pop-sci article and an interview with a PI of that experiment (in Russian, use a translator)
Then again, he also wrote a lot about the self-transforming machine elves he met while stoned out of his gourd on DMT.
The Stoned ape theory "has largely been rejected by the scientific community, who cite numerous alleged discrepancies within his theory and claim that his conclusions were arrived at via a fundamental misunderstanding of Fischer's studies" on "psychedelic drugs, schizophrenia, the perception-hallucination continuum model of altered states of consciousness, and...gustation" [1][2].