Very interesting paper! Proposes (with lower bound of 1.3% chance) that the solar system may have passed through a local interstellar cloud, which would have caused the heliosphere to shrink to smaller than the orbit of the earth (0.22 au) some 2-3 mya. This may have affected the Earth's atmosphere and climate. Scroll down for some cool illustrations of a simulation showing how the heliosphere would have been tiny with an elongated tail in a denser interstellar medium. There's also a map showing the interstellar cloud relative to the trajectory of the solar system.
That's one of those fun astronomy topics that is mind boggling to think of the forces involved to diminish the effect of Sol's solar radiation to that level.
> This may have affected the Earth's atmosphere and climate.
Adding uncertainty to climate forecasting models. Can we detect or predict changes to the interstellar medium in our path through space and improve forecasts with that? Maybe we could at least put an upper bound on the magnitude of the effect.
Punctuated equilibrium is not about higher mutation rates or even faster evolution, but about long periods of _stasis_ interrupted by "normal rate" evolution due to an upset in the equilibrium such as a sudden geographic isolation of two populations.
Are we able to determine if other star systems have experienced the same type of encounter? (Not statistically, I mean detection or instrument based)
I'm assuming it's either difficult or impossible to measure another star's heliopause. It would be fascinating to see the effects of a cold cloud interaction in "real" time!
>I'm assuming it's either difficult or impossible to measure another star's heliopause. It would be fascinating to see the effects of a cold cloud interaction in "real" time!
I'm pretty sure we observe it routinely. There are tons of beautiful pictures of stars blowing away Nursery nebula. This is the heliopause of those Stars interacting with dense interstellar medium
Presumably it has happened before in the history of the earth but it would be interesting to know what effects it had on life on earth and, by extension, the arrival and development of modern humans.
Why does this make me feel a little dirty and exposed?
Like, who knows what kinda alien DNA strands or spores are carried by the ISM?!
I wonder if it would be possible to track biodiversity increases caused by the transit? Assuming there is biological material in the ISM, perhaps some of it made it into our biosphere!
This is an amazing idea! In my response to imiric, I detail an ICM Panspermia version of the Stoned Ape Theory, and hypothesize that we could use genomic dating techniques to experimentally falsify the theory (which is probably false because we probably had magic mushrooms for many millions of years). That makes it a fun theory to work with!
Remember, modern humans appeared around 1.5-2M years ago, so this event, geologically speaking, happened shortly before the arrival of modern humans. Perhaps this event had something to do with us evolving.
Do you mean Homo Erectus or Homo Sapiens? Sapiens arrived around 300k years ago, according to Wikipedia. Erectus did indeed arrive around 2M years ago.
Must be Erectus then. This must be the time the aliens placed the Monolith on Earth (and another one on the Moon that we haven't found yet because we're WAY behind on our Moon base program).
The more I think about it the more I agree with you. I don't know why I initially felt unsettled but now that I'm thinking we might be able to actually detect if it happened (through advanced genomics techniques), I am starting to warm up to the theory.
There's even a fun tie-in with stoned ape theory (which I don't endorse, but is a fun theory). In one version of the theory, humans eat magic mushrooms and become conscious or develop higher thought. In the ISM version, magic mushroom spores - or the genes that make them psychoactive - were seeded from the ISM three million years ago, leading to the evolution of homo erectus and homo sapiens.
This is a fun theory because it would be easy to falsify with a an experiment showing that magic mushrooms evolved their hallucinatory properties much longer than 3 million years ago. But note that you'd have to do so xenogenomic theory, to control for the possibility that the material came in from the ism itself as much older than 3 million years. Such material would show terrestrial genomic age metrics, which could make us think magic mushrooms evolved long ago on the earth, when in fact it evolved in another biosphere.
Anyways, you're right! This IS making me feel more connected to the universe!
> what kinda alien DNA strands or spores are carried by the ISM?
None that we are aware (and would be fried by the earth atmosphere probably).
> Would be possible to track biodiversity increases caused by the transit
An entirely new set of new forms of life appearing from nowhere and without any known ancestor in a small line of the "evolutive script" would not be missed. This is the opposite that we observe in that age. Life evolving for the ice age, yes. A glaciation just would force the organisms to evolve or die. There is not need of any alien gardener to explain this.
I'm not saying this to be non-scientific or conspiratorial or anything. This is actually very cool!
And respectfully, I think a real xenobiologist can come up with more creative ways to get spores from the ISM into the atmosphere.
For instance maybe they come in on small meteorites, right?
Maybe they come in around the modified heliosphere termination shock, as the earth swings through it. The turbulence in the boundary layer manages to decelerate the ICM so that components of it can drift into the atmosphere on low energy trajectories. Fun right?
So to be clear if you were trying to reduce my anxiety here, that's not really what I'm feeling. I'm feeling wonder and creativity. I would prefer for you to brainstorm cute scientific mechanisms that might allow it to happen!
And I think that you're misunderstanding what I meant by a impact on the biosphere.
We wouldn't see all new species. We might see some new genes in a few species, which would have started arriving around 3 million years ago in the genomic record, and would not be explained by the ordinary arrival of new genes through mutations, either because the arrival rate would be too high or the genes arriving would be too different.
So the idea would be to think up genomic experiments and metrics that would be able to detect the arrival of exobiological material 3 million years ago, assuming that the effect would be very attenuated.
Again I think that serious geneticists and xenobiologists would have fun brainstorming ideas here. I just want to be a fly on the wall for that conversation, lol.
The problem is that people confuse science with science fiction. Is the same problem each time somebody says the name "spider" here. Oh "Children of time" tell us all about how smart are spiders"... hem. Not.
There aren't known spores found out of earth. Only on the books. But histories in those books aren't real. Biology is real.
There is not any reason to assume that a earth fungus or a fern could made a spore able to survive in a rock in the vacuum of space for thousands of years. And the reentry in the atmosphere would reduce it to ashes at the end. Super-spores from entirely new types of organisms would be spotted by taxonomists.
Those hypothetical "genomic experiments" to modify things extant yet could only happen in a limited amount of individuals.
Most probably they would never work. Think in a computer program and paste some code at a random position of characters. Maybe in the middle of a word. The probability that the program still keeps running after that is very low. The line would need to fall exactly between two closed blocks. DNA is more complicated that computer programs. You can't just introduce random genes here and there unless you have genetic scissors for exactly this problem (we have this tool but for a limited number of cases), and know exactly where and how.
As those life beings would be defective the modifications would be diluted first on a much bigger population, and cleaned by evolution or predators soon after that.
Hmm. This is not a productive conversation. Can we fix that?
Here are my concerns.
It's sounding like you have not worked much with genomics, given that you put "genomic experiments" in scare quotes, speak in terms of analogies with computer code, and don't seem to be aware of work in genomic archeology. We don't know exactly where random genes came from, but with mutation models we can indeed get some inkling about when a gene has arrived, and how it mutated. But your're acting like genomic archeology methods just don't exist, or as if you've never read even a paper in genomic archeology. Let me know if you want me to link you to papers here, that stuff is actually really cool.
You also ignored the idea that termination shock could help things get into the atmosphere, suggesting that you think about atmospheric entries in sciences fiction terms of "everything burns up", rather than considering all the possible physical trajectories that matter could take where it wouldn't burn up (especially if it's shielded by rock - more on this later).
You also make a bad assumption about the spores. They would need to survive millions of years in space, and they could have evolved in conditions much different from terrestrial ones, including in systems where space travel would have been routine.
You're also unaware of the xenobiological work here, and might not even think xenobiology is real biology. Namely, when you say there's no reason to think spores could survive space, you are either unaware of or discount the xenobiology work on spatial spores:
For example, one of the papers in the list above suggests that 40 to 100% of bacteria would survive a planetary strike scattering them up into space. And that's bacteria! It turns out that tiny things are very very resistant against high accelerations, suggesting that spores might be able to make the landing too, especially if shielded by rock.
Then you're hand waving the idea that even if there was some biological contribution it would surely be wiped away by evolution and predators. Again, why? We're talking about microbes and fungi, which share their genes pretty prolifically. There are methods to look at a microbe population's genetics, backtrack the genes, calculate when they appeared and mutated, etc. A whole field of science you are just discounting.
There's there's no kind of precision to your hypothesizing, no citations or nods to existing work. It's impossible to have a scientific conversation like this - you are making pseudoscientific speculation of the kind that you're trying to fight.
It would be nice if you could say that you're not very interested in biology/genomics/xenobiology, and disengage the topic if you don't like theorizing, brainstorming, and consulting scientific literature. I understand that you are motivated to reduce the pseudoscience on HN, which is a noble goal. The problem is that you don't know enough science to tell science from science fiction / pseudoscience. And you're cramping my style, turning a potentially fun scientific conversation into pseudoscientific hand waving and muddling. I don't like that, and request a more scientific conversation from you if you please. We can have some kind of constructive and educational discussion if you want.
> By studying geological radioisotopes on Earth, we can learn about the past of the heliosphere. Fe60 is predominantly produced in supernova explosions and becomes trapped in interstellar dust grains. Fe60 has a half-life of 2.6 Myr, and Pu244 has a half-life of 80.7 Myr. Fe60 is not naturally produced on Earth, and so its presence is an indicator of supernova explosions within the last few (~10) million years.
Interesting question! From the Dendrochronology article on Wikipedia it seems we can at most go 14k years into the past with tree rings:
> Bard et al write in 2023: "The oldest tree-ring series are known as floating since, while their constituent rings can be counted to create a relative internal chronology, they cannot be dendro-matched with the main Holocene absolute chronology. However, 14C analyses performed at high resolution on overlapped absolute and floating tree-rings series enable one to link them almost absolutely and hence to extend the calibration on annual tree rings until ≈13 900 cal yr BP."
None! The Sun has a forcefield called the heliosphere to protect it, and this protects the planets as well. This paper is arguing that the interstellar medium may have been dense enough to shrink the heliosphere to within the orbit of some planets, but it'd take a helluva lot more to shrink it down to the Sun's surface.
I understand, but given the dramatic change I'd expect some things to "bend" a little. Perhaps literally, like solar flares? Does "holding them closer" increase/decrease surface temperature?
Fair enough, I'm sure "none" is a slight exaggeration.
Two effects I could see (but have no source for) are:
1. A slightly increased return radiation due to the increased proximity of the heliopause and the the increased collision rate with the denser interstellar medium. The radiation from this should reach the surface of the Sun and slightly increase surface temps, but this effect would be dwarfed by the amount of radiation already coming from the Sun itself.
2. A tighter coupling of the Sun's magnetism to the stellar wind and interstellar magnetic field. This would slow down the Sun's rotation slightly, and it if increased differential rotation it could cause an increase in solar flare activity.
It’s not every day you read something that completely boggles your mind. Our solar system passes through interstellar clouds and it can affect our planet. Wow.
Reminds me of the plot of "Exit Earth" by Martin Caidin where humanity has to evacuate the planet in an ark to survive passage through an interstellar dust cloud. Martin Caidin is known more for "Cyborg", the book that was used as the basis for the TV show "The Six Million Dollar Man".
Just a comment, I sent this to my advisor who was an astrophysicist a few years back (he and I are in plasma physics today) and here's something he pointed out,
"[...]Abraham Loeb is about as controversial of a figure in astronomy as you can find. He is also the head of a UFO monitoring project and he still insists that the rod like object that telescopes saw pass through the solar system about a decade ago had an extraterrestrial origin."
Googled his name (he's one of the co-authors of this article) and found this on his wiki page:
"In 2018, he suggested that alien space craft may be in the Solar System, using ʻOumuamua as an example.[7] In 2023, he claimed to have recovered material from an interstellar meteor that could be evidence of an alien starship,[8] which some experts criticized as hasty and sensational,[9][10] and for which other experts found more Earth-related explanations instead, demonstrating that the seismic signal attributed by Loeb to the alleged interstellar space craft was actually caused by ordinary truck traffic.[11]"
Take from this what you will. The section on the Galileo project talks more about the controversy surrounding him.
He's controversial but not crazy. Lots of interesting people are controversial. I think you understand that, but I'm sharing this comment so that others aren't immediately turned off at the notion.
Can you believe that Galileo guy? What a crank. What a controversial figure. He actually insists that the Earth goes around the Sun. That's not science, that's just a madman, all our scientists know that the truth is the other way around. Don't read this new paper he wrote guys, look at the controversy surrounding him. Take from this what you will.
I learned to keep an open mind for even the craziest ideas - not because they sound funny, but because my mind might not comprehend them yet. Remember that Einstein was ridiculed for years by respective physicists [1]. At some point, Lord Kelvin even said physics was no longer attractive because there was nothing to discover (around 1900).
Counter-counterpoint: "They laughed at Columbus, they laughed at Fulton, they laughed at the Wright Brothers. But they also laughed at Bozo the Clown." — Carl Sagan, Broca's Brain (1979).
65 comments
[ 2.9 ms ] story [ 131 ms ] threadAdding uncertainty to climate forecasting models. Can we detect or predict changes to the interstellar medium in our path through space and improve forecasts with that? Maybe we could at least put an upper bound on the magnitude of the effect.
https://en.m.wikipedia.org/wiki/Local_Bubble
Punctuated equilibrium: https://en.wikipedia.org/wiki/Punctuated_equilibrium
Higher levels of radiation do correlate to higher rates of genetic mutation; presumably because radiation so affects transcription.
Does the punctuated equilibrium theory model radiation level in estimating rate of evolution?
Rate of evolution: https://en.wikipedia.org/wiki/Rate_of_evolution
I don't know if I did this correctly but that's only ~27kJ per second of mass energy. I thought it would be a lot more.
Yet another example of just how big space is, and how empty atoms are
Which is why you normally talk of "x% of the speed of light", e.g. 99% of the speed of light.
I'm assuming it's either difficult or impossible to measure another star's heliopause. It would be fascinating to see the effects of a cold cloud interaction in "real" time!
I'm pretty sure we observe it routinely. There are tons of beautiful pictures of stars blowing away Nursery nebula. This is the heliopause of those Stars interacting with dense interstellar medium
Like, who knows what kinda alien DNA strands or spores are carried by the ISM?!
I wonder if it would be possible to track biodiversity increases caused by the transit? Assuming there is biological material in the ISM, perhaps some of it made it into our biosphere!
Very fun!
https://en.wikipedia.org/wiki/Panspermia
https://en.wikipedia.org/wiki/Human
https://en.wikipedia.org/wiki/Homo_erectus
There's even a fun tie-in with stoned ape theory (which I don't endorse, but is a fun theory). In one version of the theory, humans eat magic mushrooms and become conscious or develop higher thought. In the ISM version, magic mushroom spores - or the genes that make them psychoactive - were seeded from the ISM three million years ago, leading to the evolution of homo erectus and homo sapiens.
This is a fun theory because it would be easy to falsify with a an experiment showing that magic mushrooms evolved their hallucinatory properties much longer than 3 million years ago. But note that you'd have to do so xenogenomic theory, to control for the possibility that the material came in from the ism itself as much older than 3 million years. Such material would show terrestrial genomic age metrics, which could make us think magic mushrooms evolved long ago on the earth, when in fact it evolved in another biosphere.
Anyways, you're right! This IS making me feel more connected to the universe!
None that we are aware (and would be fried by the earth atmosphere probably).
> Would be possible to track biodiversity increases caused by the transit
An entirely new set of new forms of life appearing from nowhere and without any known ancestor in a small line of the "evolutive script" would not be missed. This is the opposite that we observe in that age. Life evolving for the ice age, yes. A glaciation just would force the organisms to evolve or die. There is not need of any alien gardener to explain this.
And respectfully, I think a real xenobiologist can come up with more creative ways to get spores from the ISM into the atmosphere.
For instance maybe they come in on small meteorites, right?
Maybe they come in around the modified heliosphere termination shock, as the earth swings through it. The turbulence in the boundary layer manages to decelerate the ICM so that components of it can drift into the atmosphere on low energy trajectories. Fun right?
So to be clear if you were trying to reduce my anxiety here, that's not really what I'm feeling. I'm feeling wonder and creativity. I would prefer for you to brainstorm cute scientific mechanisms that might allow it to happen!
We wouldn't see all new species. We might see some new genes in a few species, which would have started arriving around 3 million years ago in the genomic record, and would not be explained by the ordinary arrival of new genes through mutations, either because the arrival rate would be too high or the genes arriving would be too different.
So the idea would be to think up genomic experiments and metrics that would be able to detect the arrival of exobiological material 3 million years ago, assuming that the effect would be very attenuated.
Again I think that serious geneticists and xenobiologists would have fun brainstorming ideas here. I just want to be a fly on the wall for that conversation, lol.
There aren't known spores found out of earth. Only on the books. But histories in those books aren't real. Biology is real.
There is not any reason to assume that a earth fungus or a fern could made a spore able to survive in a rock in the vacuum of space for thousands of years. And the reentry in the atmosphere would reduce it to ashes at the end. Super-spores from entirely new types of organisms would be spotted by taxonomists.
Those hypothetical "genomic experiments" to modify things extant yet could only happen in a limited amount of individuals.
Most probably they would never work. Think in a computer program and paste some code at a random position of characters. Maybe in the middle of a word. The probability that the program still keeps running after that is very low. The line would need to fall exactly between two closed blocks. DNA is more complicated that computer programs. You can't just introduce random genes here and there unless you have genetic scissors for exactly this problem (we have this tool but for a limited number of cases), and know exactly where and how.
As those life beings would be defective the modifications would be diluted first on a much bigger population, and cleaned by evolution or predators soon after that.
Here are my concerns.
It's sounding like you have not worked much with genomics, given that you put "genomic experiments" in scare quotes, speak in terms of analogies with computer code, and don't seem to be aware of work in genomic archeology. We don't know exactly where random genes came from, but with mutation models we can indeed get some inkling about when a gene has arrived, and how it mutated. But your're acting like genomic archeology methods just don't exist, or as if you've never read even a paper in genomic archeology. Let me know if you want me to link you to papers here, that stuff is actually really cool.
You also ignored the idea that termination shock could help things get into the atmosphere, suggesting that you think about atmospheric entries in sciences fiction terms of "everything burns up", rather than considering all the possible physical trajectories that matter could take where it wouldn't burn up (especially if it's shielded by rock - more on this later).
You also make a bad assumption about the spores. They would need to survive millions of years in space, and they could have evolved in conditions much different from terrestrial ones, including in systems where space travel would have been routine.
You're also unaware of the xenobiological work here, and might not even think xenobiology is real biology. Namely, when you say there's no reason to think spores could survive space, you are either unaware of or discount the xenobiology work on spatial spores:
https://scholar.google.com/scholar?q=Panspermia%20spore&btnG...
For example, one of the papers in the list above suggests that 40 to 100% of bacteria would survive a planetary strike scattering them up into space. And that's bacteria! It turns out that tiny things are very very resistant against high accelerations, suggesting that spores might be able to make the landing too, especially if shielded by rock.
Then you're hand waving the idea that even if there was some biological contribution it would surely be wiped away by evolution and predators. Again, why? We're talking about microbes and fungi, which share their genes pretty prolifically. There are methods to look at a microbe population's genetics, backtrack the genes, calculate when they appeared and mutated, etc. A whole field of science you are just discounting.
There's there's no kind of precision to your hypothesizing, no citations or nods to existing work. It's impossible to have a scientific conversation like this - you are making pseudoscientific speculation of the kind that you're trying to fight.
It would be nice if you could say that you're not very interested in biology/genomics/xenobiology, and disengage the topic if you don't like theorizing, brainstorming, and consulting scientific literature. I understand that you are motivated to reduce the pseudoscience on HN, which is a noble goal. The problem is that you don't know enough science to tell science from science fiction / pseudoscience. And you're cramping my style, turning a potentially fun scientific conversation into pseudoscientific hand waving and muddling. I don't like that, and request a more scientific conversation from you if you please. We can have some kind of constructive and educational discussion if you want.
Either way I do hope that you have a good day!
I remember reading that dinosaur meteorite was discovered to have fallen in spring by those marks
surely regular pattern of getting in-out of heliosphere be noticeable?
Why do you say that? What would you look for?
> By studying geological radioisotopes on Earth, we can learn about the past of the heliosphere. Fe60 is predominantly produced in supernova explosions and becomes trapped in interstellar dust grains. Fe60 has a half-life of 2.6 Myr, and Pu244 has a half-life of 80.7 Myr. Fe60 is not naturally produced on Earth, and so its presence is an indicator of supernova explosions within the last few (~10) million years.
> Bard et al write in 2023: "The oldest tree-ring series are known as floating since, while their constituent rings can be counted to create a relative internal chronology, they cannot be dendro-matched with the main Holocene absolute chronology. However, 14C analyses performed at high resolution on overlapped absolute and floating tree-rings series enable one to link them almost absolutely and hence to extend the calibration on annual tree rings until ≈13 900 cal yr BP."
https://en.wikipedia.org/wiki/Dendrochronology?wprov=sfti1#C...
Interestingly it seems that tree ring chronologies can be mapped to increases in cosmic radiation named "Miyake events".
https://en.wikipedia.org/wiki/Miyake_event
He hypothesizes that cosmic ray bursts are responsible for mutational leaps in evolution.
This seems similar.
Leaves are money!
https://en.wikipedia.org/wiki/Heliosphere
Two effects I could see (but have no source for) are:
1. A slightly increased return radiation due to the increased proximity of the heliopause and the the increased collision rate with the denser interstellar medium. The radiation from this should reach the surface of the Sun and slightly increase surface temps, but this effect would be dwarfed by the amount of radiation already coming from the Sun itself.
2. A tighter coupling of the Sun's magnetism to the stellar wind and interstellar magnetic field. This would slow down the Sun's rotation slightly, and it if increased differential rotation it could cause an increase in solar flare activity.
"[...]Abraham Loeb is about as controversial of a figure in astronomy as you can find. He is also the head of a UFO monitoring project and he still insists that the rod like object that telescopes saw pass through the solar system about a decade ago had an extraterrestrial origin."
Googled his name (he's one of the co-authors of this article) and found this on his wiki page:
"In 2018, he suggested that alien space craft may be in the Solar System, using ʻOumuamua as an example.[7] In 2023, he claimed to have recovered material from an interstellar meteor that could be evidence of an alien starship,[8] which some experts criticized as hasty and sensational,[9][10] and for which other experts found more Earth-related explanations instead, demonstrating that the seismic signal attributed by Loeb to the alleged interstellar space craft was actually caused by ordinary truck traffic.[11]"
Take from this what you will. The section on the Galileo project talks more about the controversy surrounding him.
https://en.wikipedia.org/wiki/Avi_Loeb
[1] https://daily.jstor.org/why-no-one-believed-einstein/
I know what you mean -- "it's an alien artifact/spaceship!" -- but, literally, the sentence is true, no? It did not originate on Earth.