5 ms·

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?

hnarn 3y ago
Reminds me of a really interesting video Kurzgesagt posted recently: https://m.youtube.com/watch?v=JOiGEI9pQBs https://m.youtube.com/watch?v=JOiGEI9pQBs
- JumpCrisscross 3y ago
  The habitable epoch, when "the cosmic microwave background (CMB) had a temperature of 273–373 K (0–100 °C), allowing early rocky planets (if any existed) to have liquid water chemistry on their surface and be habitable, irrespective of their distance from a star," has always fascinated me [1]. Space itself was room temperature. 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. [1] https://lweb.cfa.harvard.edu/~loeb/habitable.pdf https://lweb.cfa.harvard.edu/~loeb/habitable.pdf
  - samplatt 3y ago
    I'm having troubles following the math on that paper. If the beginning of the Habitable Epoch was 10-17MY after the big bang, when was the end?
    - hnarn 3y ago
      Not strictly an answer to your question regarding the math, but the video I linked above does mention an estimate for how long the period might have been.
fnordpiglet 3y ago
Why does an asteroid have to hit the earth? Life is constantly being shed from the upper atmosphere into space right now. As we travel through space we leave a plume of life behind us. Certainly almost none of it survives, but almost isn’t none, and a lot of life spreads as hardened spores that can withstand extreme conditions until more favorable conditions present and they “wake up.”
- crazygringo 3y ago
  > Life is constantly being shed from the upper atmosphere into space right now. As we travel through space we leave a plume of life behind us. 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. [1] https://en.wikipedia.org/wiki/Atmospheric_escape https://en.wikipedia.org/wiki/Atmospheric_escape
  - londons_explore 3y ago
    I suspect the conclusion here depends entirely on upper atmosphere winds which I don't think are well studied.
    - lupire 3y ago
      Upper atmosphere winds are well within the Earth's gravity well. 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.
explorigin 3y ago
Astronomically low. (I'll see myself out.)
adolph 3y ago
One of the main ideas explained in this video is that the very early universe (i.e. the universe “right after the Big Bang” in cosmic timescales) might have been habitable for a short period of time. During this time window, the right temperature to support life wouldn’t have been restricted to the proximity of stars, but would have instead taken place absolutely everywhere in space due to the intrinsic temperature of the universe itself. https://sites.google.com/view/sources-big-bang-life/ https://sites.google.com/view/sources-big-bang-life/ https://youtu.be/JOiGEI9pQBs?si=kOHM_l0saPkEhWcX https://youtu.be/JOiGEI9pQBs?si=kOHM_l0saPkEhWcX
- anonymouskimmer 3y ago
  > The second one is an observation about the rate at which the different genomes on Earth have changed over evolutionary history. When extrapolated back into the past, this evolution rate of genomes suggests that the current lineage of life on Earth might be at least 10 billion years old, 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.
  - adolph 3y ago
    It sometimes sounds the state of the art is headed there, see Cronin et al regarding “Assembly theory explains and quantifies selection and evolution” https://www.nature.com/articles/s41586-023-06600-9 https://www.nature.com/articles/s41586-023-06600-9
- nkrisc 3y ago
  We often think about life arising in one location and then spreading across the galaxy or universe. Quite interesting to consider instead life arising everywhere and then being reduced to only a few (maybe one) remaining pockets across the entire universe, or not at all. 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.
- s1artibartfast 3y ago
resolutebat 3y ago
Terence McKenna's theory was that human intelligence stems from psilocybin-containing mushroom spores hitching a ride on asteroids. Then again, he also wrote a lot about the self-transforming machine elves he met while stoned out of his gourd on DMT.
- NoPicklez 3y ago
  I'd believe both of those things
  - sitkack 3y ago
    The fungi are actually probes sent from an ancient civilization, a root kit for life it finds to make it take to the stars.
    - euroderf 3y ago
      Not just a root kit. Communications too.
- JumpCrisscross 3y ago
  > Terence McKenna's theory was that human intelligence stems from psilocybin-containing mushroom spores 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]. [1] https://en.wikipedia.org/wiki/Stoned_ape_theory https://en.wikipedia.org/wiki/Stoned_ape_theory [2] https://en.wikipedia.org/wiki/Roland_L._Fischer https://en.wikipedia.org/wiki/Roland_L._Fischer
downrightmike 3y ago
After the big bang, there was likely many millions of years where the universe was a comfortable temperature that would have allowed life to evolve there first. Which eventually cooled and died out until it met the right conditions. Probably why space smells like burnt food "Other astronauts have described it in similar yet varying ways: "burning metal," "a distinct odor of ozone, an acrid smell," "walnuts and brake pads," "gunpowder" and even "burnt almond cookie." " https://science.howstuffworks.com/space-smell.htm#:~:text=Other%20astronauts%20have%20described%20it,reports%20differ%20slightly%20in%20their%20%22 https://science.howstuffworks.com/space-smell.htm#:~:text=Ot...
- candiodari 3y ago
  "electrical smell", "burnt almond cookie" is the smell people who survived report HCN to have. And it's not that space is full of a lethal-on-touch gas, that's the smell your nerves report when the sensory cells are dying faster than they can pass on a chemical signal.
- dotancohen 3y ago
  But during that time, the elements necessary for life as we know it did not yet exist.
  - 867-5309 3y ago
    which time would that be?
  - downrightmike 3y ago
    Kurzgesagt Just for fun: https://www.youtube.com/watch?v=JOiGEI9pQBs https://www.youtube.com/watch?v=JOiGEI9pQBs
7thaccount 3y ago
I first read about this ages ago as a kid and was fascinated. I never figured it was probable though. Years later I'm finding it more and more likely in my completely worthless and undereducated opinion. It'd be crazy to eventually find out that many planets out there have similar DNA. 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.
- xyzzy_plugh 3y ago
  Alternatively non-orientable wormholes would produce the same effects. Would be cool either way!
orbital-decay 3y ago
There was that ISS experiment during multiple spacewalks that discovered marine microorganisms on the outer surface of the space station that got there somehow, many of them surviving the conditions. It's hard to explain by the contamination alone because some species were endemic to the places well outside the trajectory of the launchers. 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/ 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 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)
EasyMark 3y ago
there's absolutely no way to calculate that, there are simply too many variables to say anything other than probably greater than 0 but less than 1

hnarn 3y ago

Reminds me of a really interesting video Kurzgesagt posted recently: https://m.youtube.com/watch?v=JOiGEI9pQBs https://m.youtube.com/watch?v=JOiGEI9pQBs

JumpCrisscross 3y ago
The habitable epoch, when "the cosmic microwave background (CMB) had a temperature of 273–373 K (0–100 °C), allowing early rocky planets (if any existed) to have liquid water chemistry on their surface and be habitable, irrespective of their distance from a star," has always fascinated me [1]. Space itself was room temperature. 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. [1] https://lweb.cfa.harvard.edu/~loeb/habitable.pdf https://lweb.cfa.harvard.edu/~loeb/habitable.pdf
- samplatt 3y ago
  I'm having troubles following the math on that paper. If the beginning of the Habitable Epoch was 10-17MY after the big bang, when was the end?
  - hnarn 3y ago
    Not strictly an answer to your question regarding the math, but the video I linked above does mention an estimate for how long the period might have been.

fnordpiglet 3y ago

Why does an asteroid have to hit the earth? Life is constantly being shed from the upper atmosphere into space right now. As we travel through space we leave a plume of life behind us. Certainly almost none of it survives, but almost isn’t none, and a lot of life spreads as hardened spores that can withstand extreme conditions until more favorable conditions present and they “wake up.”

crazygringo 3y ago
> Life is constantly being shed from the upper atmosphere into space right now. As we travel through space we leave a plume of life behind us. 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. [1] https://en.wikipedia.org/wiki/Atmospheric_escape https://en.wikipedia.org/wiki/Atmospheric_escape
- londons_explore 3y ago
  I suspect the conclusion here depends entirely on upper atmosphere winds which I don't think are well studied.
  - lupire 3y ago
    Upper atmosphere winds are well within the Earth's gravity well. 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.

explorigin 3y ago

Astronomically low. (I'll see myself out.)

adolph 3y ago

One of the main ideas explained in this video is that the very early universe (i.e. the universe “right after the Big Bang” in cosmic timescales) might have been habitable for a short period of time. During this time window, the right temperature to support life wouldn’t have been restricted to the proximity of stars, but would have instead taken place absolutely everywhere in space due to the intrinsic temperature of the universe itself. https://sites.google.com/view/sources-big-bang-life/ https://sites.google.com/view/sources-big-bang-life/ https://youtu.be/JOiGEI9pQBs?si=kOHM_l0saPkEhWcX https://youtu.be/JOiGEI9pQBs?si=kOHM_l0saPkEhWcX

anonymouskimmer 3y ago
> The second one is an observation about the rate at which the different genomes on Earth have changed over evolutionary history. When extrapolated back into the past, this evolution rate of genomes suggests that the current lineage of life on Earth might be at least 10 billion years old, 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.
- adolph 3y ago
  It sometimes sounds the state of the art is headed there, see Cronin et al regarding “Assembly theory explains and quantifies selection and evolution” https://www.nature.com/articles/s41586-023-06600-9 https://www.nature.com/articles/s41586-023-06600-9
nkrisc 3y ago
We often think about life arising in one location and then spreading across the galaxy or universe. Quite interesting to consider instead life arising everywhere and then being reduced to only a few (maybe one) remaining pockets across the entire universe, or not at all. 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.
s1artibartfast 3y ago

resolutebat 3y ago

Terence McKenna's theory was that human intelligence stems from psilocybin-containing mushroom spores hitching a ride on asteroids. Then again, he also wrote a lot about the self-transforming machine elves he met while stoned out of his gourd on DMT.

NoPicklez 3y ago
I'd believe both of those things
- sitkack 3y ago
  The fungi are actually probes sent from an ancient civilization, a root kit for life it finds to make it take to the stars.
  - euroderf 3y ago
    Not just a root kit. Communications too.
JumpCrisscross 3y ago
> Terence McKenna's theory was that human intelligence stems from psilocybin-containing mushroom spores 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]. [1] https://en.wikipedia.org/wiki/Stoned_ape_theory https://en.wikipedia.org/wiki/Stoned_ape_theory [2] https://en.wikipedia.org/wiki/Roland_L._Fischer https://en.wikipedia.org/wiki/Roland_L._Fischer

downrightmike 3y ago

After the big bang, there was likely many millions of years where the universe was a comfortable temperature that would have allowed life to evolve there first. Which eventually cooled and died out until it met the right conditions. Probably why space smells like burnt food "Other astronauts have described it in similar yet varying ways: "burning metal," "a distinct odor of ozone, an acrid smell," "walnuts and brake pads," "gunpowder" and even "burnt almond cookie." " https://science.howstuffworks.com/space-smell.htm#:~:text=Other%20astronauts%20have%20described%20it,reports%20differ%20slightly%20in%20their%20%22 https://science.howstuffworks.com/space-smell.htm#:~:text=Ot...

candiodari 3y ago
"electrical smell", "burnt almond cookie" is the smell people who survived report HCN to have. And it's not that space is full of a lethal-on-touch gas, that's the smell your nerves report when the sensory cells are dying faster than they can pass on a chemical signal.
dotancohen 3y ago
But during that time, the elements necessary for life as we know it did not yet exist.
- 867-5309 3y ago
  which time would that be?
- downrightmike 3y ago
  Kurzgesagt Just for fun: https://www.youtube.com/watch?v=JOiGEI9pQBs https://www.youtube.com/watch?v=JOiGEI9pQBs

7thaccount 3y ago

I first read about this ages ago as a kid and was fascinated. I never figured it was probable though. Years later I'm finding it more and more likely in my completely worthless and undereducated opinion. It'd be crazy to eventually find out that many planets out there have similar DNA. 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.

xyzzy_plugh 3y ago
Alternatively non-orientable wormholes would produce the same effects. Would be cool either way!

orbital-decay 3y ago

There was that ISS experiment during multiple spacewalks that discovered marine microorganisms on the outer surface of the space station that got there somehow, many of them surviving the conditions. It's hard to explain by the contamination alone because some species were endemic to the places well outside the trajectory of the launchers. 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/ 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 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)

EasyMark 3y ago

there's absolutely no way to calculate that, there are simply too many variables to say anything other than probably greater than 0 but less than 1