7 ms·

This has big implications for the Fermi Paradox: https://en.wikipedia.org/wiki/Fermi_paradox https://en.wikipedia.org/wiki/Fermi_paradox In particular, the jum

by pkrein 8y ago

This has big implications for the Fermi Paradox: https://en.wikipedia.org/wiki/Fermi_paradox https://en.wikipedia.org/wiki/Fermi_paradox In particular, the jump from unicellular to multicellular life is (was) one of the top leading candidates for the Great Filter. https://en.wikipedia.org/wiki/Great_Filter https://en.wikipedia.org/wiki/Great_Filter Importantly, it was one of the filter candidates "behind" us. It will be exciting to see if other potential filter steps can be so conclusively eliminated over time.

SlipperySlope 8y ago
Awesome point. I for one believe that filter steps remaining or yet to be found will eliminate the chance for Alien intelligence. It would appear more certain than ever that within a few hundred thousand years robotic self replicating probes will populate most of the galaxy exploring for us.
burlesona 8y ago
Exciting, but also slightly terrifying. I know this isn’t universal, but I, for one, very much hope that the filter is behind us and not in front of us. That being said I’m not too shocked. The transition from unicellular to multicellular has always seemed like less of a hurdle to me compared to the start of unicellular life itself.
- MRD85 8y ago
  The jump to the start of unicellular life seems like the big stumbling block. It might be so incredibly rare that it's lucky for it to even happen once in the universe.
  - rdlecler1 8y ago
    You need heredity, differential reproduction and selection. We really just need to start with a single case of a self-replicating system. Hard yes, but with countless trials running in parallel for millions of years it seems intuitively possible
  - paulryanrogers 8y ago
    If the universe exists for eternity, and in approximately the same form, then even very small odds may approach near certainty.
  - est31 8y ago
    Evolution is a process rooted in randomness. The more faces a dice has, the longer you need to throw it to get the highest number. Or, reversely: the longer you have to throw your dice to get the highest number, the more faces it generally has. It took "only" < 400 million years for life to develop, meaning unicellular life, but it took 3 billion years for multicellular life to develop. If we apply this basic rule, multicellular life seems the hard thing. Of course though, statistics wise this is pretty crappy ground to stand on because we only have one sample :).
    - gus_massa 8y ago
      The hard part is (probably) the transition from Prokaryotes to Eukaryotes. The transition from unicelular Eukaryotes to multicelular Eukaryotes is (probably) easy [1] . Edit: [1] From https://en.wikipedia.org/wiki/Multicellular_organism#Occurrence https://en.wikipedia.org/wiki/Multicellular_organism#Occurre... > Multicellularity has evolved independently at least 46 times in eukaryotes, and also in some prokaryotes, [...] . However, complex multicellular organisms evolved only in six eukaryotic groups [...]
    - perl4ever 8y ago
      "It took "only" < 400 million years for life to develop" Yes, that's what people assume, but the universe existed for billions of years before that, so what if life might have used all that time to evolve before it landed on Earth deep inside some rocks?
    - MRD85 8y ago
      One sample is hard to read because even low odds can happen. Picture the following statement: "The chance of life forming anywhere in the universe over a 100 billion year period is equal to 1 in Graham's number". If this statement is true then it is incredibly unlikely life forms in our universe at our current stage exist. Low odds can occur and the only reason anyone is here to observe them is because they did occur. Since we only know of life forming once we cannot make assumptions about the odds of it happening.
  - cmrdporcupine 8y ago
    Unicellular in the form of bacterium may in fact not be that much of a jump. It may even have happened twice in the form of archaea and bacterium. The jump from prokaryotic to eukaryotic is far more intimidating.
    - andrewflnr 8y ago
      That's actually happened a bunch of times, too. I'm just going to link to a comment I made a while back: https://news.ycombinator.com/item?id=18456049 https://news.ycombinator.com/item?id=18456049 "Diatom-derived plastids" blew my mind.
- vichu 8y ago
  Not to be too pessimistic, but there's no reason that there should only be one "Great Filter". There could easily be multiple astronomically improbable events barring interstellar civilizations from bearing fruition. It might be just as improbable for unicellular life to form as it is for unicellular life to beget multicellular life, so on and so forth.
  - devoply 8y ago
    The great filter exists at all times as cited by the fact that the longevity of a species does not guarantee their future survival. All life may die off at any time.
  - bduerst 8y ago
    Or even reason to assume that exobiotic life is cellular, and needed to jump from singular to multi-cellular structures like ours did on this planet.
    - andrewflnr 8y ago
      I mean, in principle, but that's probably like assuming that exobiology is carbon based. Carbon and cells are both really super useful.
dukoid 8y ago
Is it really that much of a paradox? - "Metallicity": We probably need a recent / "Population I" star, i.e. it' s probably unlikely that there can be civilizations much older than us (in astronomical dimensions): https://en.wikipedia.org/wiki/Stellar_population#Population_I_stars https://en.wikipedia.org/wiki/Stellar_population#Population_... - In 1.1 billion years from now, the Sun will be 10% brighter than it is today, and this increase in luminosity will also mean an increase in heat energy, which Earth’s atmosphere will absorb. This will trigger a moist greenhouse effect here on Earth that is similar to the runaway warming that turned Venus into the hellish environment we see there today. So we have appeared only after 80% of the "usable" life span of our star has already been over -- a window that might be easy to miss (an larger stars burn even faster)
- est31 8y ago
  You don't need an astronomically old civilization for it to have galaxy-wide impact. Already a "few" million years should be enough to colonize a dead-except-for-you galaxy.
azernik 8y ago
One of the interesting ones I've heard talk about lately is the "interstellar travel" step - Earth is on the lower end of the size range for rocky planets that can support an atmosphere and magnetic field to shield surface life from radiation. And because of the tyranny of the rocket equation, life developing on larger rocky planets may have a much harder time reaching orbit. A good demo video: https://www.youtube.com/watch?v=amjuJJwI3iM https://www.youtube.com/watch?v=amjuJJwI3iM On a planet with twice the Earth's mass, it would take a larger-than-Saturn-sized rocket to put a Mercury-sized payload into orbit. EDIT: And said Mercury-sized payload would have to spend more of its mass on heat shielding than the human Mercury capsule if it's intended to come back down.
- SimbaOnSteroids 8y ago
  Yes but the rocket equation wouldn't stop intelligent species from going "loud" with radio signals.
  - akiselev 8y ago
    The rocket equation itself, no, but the planet mass would also have drastic effects on the evolution of species. On our planet, high density fibrous plants like trees have an advantage when it comes to access to the sun but what if on a bigger planet, that advantage goes to plants than can emit a spidersilk-like material to float on the wind in colonies? There goes a practically infinitely renewable building material that can be used for almost anything until the industrial age. How can a civilization get to the electronic age when they spend all their time between extinction events hauling rocks and mining ores to build 2 story dwellings? There's just so many unknowns.
    - fsloth 8y ago
      Not only dwellings but fuel as well. I mean, if you don't have trees how are you going to invent fire... Some people consider cooking a critical step in our evolution (cooking enables harvesting more calories from food). With no good fuel available cooking could also be ... off the menu.
taneq 8y ago
Someone evolved a multicellular yeast with a similar approach back in 2011 or so. They used centrifuging to select for larger 'clumps' of yeast, rather than a predator to eat the smaller ones, but still pretty similar. https://www.newscientist.com/article/mg21028184-300-lab-yeast-make-evolutionary-leap-to-multicellularity/ https://www.newscientist.com/article/mg21028184-300-lab-yeas...
DavidSJ 8y ago
Yes, although keep in mind we already knew of three independent evolutions of multicellularity — animals, plants, and fungi — so it arguably couldn’t be an improbable enough transition to qualify for great filter status.
- EamonnMR 8y ago
  Don't forget the humble Volvox! https://en.m.wikipedia.org/wiki/Volvox https://en.m.wikipedia.org/wiki/Volvox

by pkrein 8y ago

SlipperySlope 8y ago

Awesome point. I for one believe that filter steps remaining or yet to be found will eliminate the chance for Alien intelligence. It would appear more certain than ever that within a few hundred thousand years robotic self replicating probes will populate most of the galaxy exploring for us.

burlesona 8y ago

Exciting, but also slightly terrifying. I know this isn’t universal, but I, for one, very much hope that the filter is behind us and not in front of us. That being said I’m not too shocked. The transition from unicellular to multicellular has always seemed like less of a hurdle to me compared to the start of unicellular life itself.

MRD85 8y ago
The jump to the start of unicellular life seems like the big stumbling block. It might be so incredibly rare that it's lucky for it to even happen once in the universe.
- rdlecler1 8y ago
  You need heredity, differential reproduction and selection. We really just need to start with a single case of a self-replicating system. Hard yes, but with countless trials running in parallel for millions of years it seems intuitively possible
- paulryanrogers 8y ago
  If the universe exists for eternity, and in approximately the same form, then even very small odds may approach near certainty.
- est31 8y ago
  Evolution is a process rooted in randomness. The more faces a dice has, the longer you need to throw it to get the highest number. Or, reversely: the longer you have to throw your dice to get the highest number, the more faces it generally has. It took "only" < 400 million years for life to develop, meaning unicellular life, but it took 3 billion years for multicellular life to develop. If we apply this basic rule, multicellular life seems the hard thing. Of course though, statistics wise this is pretty crappy ground to stand on because we only have one sample :).
  - gus_massa 8y ago
    The hard part is (probably) the transition from Prokaryotes to Eukaryotes. The transition from unicelular Eukaryotes to multicelular Eukaryotes is (probably) easy [1] . Edit: [1] From https://en.wikipedia.org/wiki/Multicellular_organism#Occurrence https://en.wikipedia.org/wiki/Multicellular_organism#Occurre... > Multicellularity has evolved independently at least 46 times in eukaryotes, and also in some prokaryotes, [...] . However, complex multicellular organisms evolved only in six eukaryotic groups [...]
  - perl4ever 8y ago
    "It took "only" < 400 million years for life to develop" Yes, that's what people assume, but the universe existed for billions of years before that, so what if life might have used all that time to evolve before it landed on Earth deep inside some rocks?
  - MRD85 8y ago
    One sample is hard to read because even low odds can happen. Picture the following statement: "The chance of life forming anywhere in the universe over a 100 billion year period is equal to 1 in Graham's number". If this statement is true then it is incredibly unlikely life forms in our universe at our current stage exist. Low odds can occur and the only reason anyone is here to observe them is because they did occur. Since we only know of life forming once we cannot make assumptions about the odds of it happening.
- cmrdporcupine 8y ago
  Unicellular in the form of bacterium may in fact not be that much of a jump. It may even have happened twice in the form of archaea and bacterium. The jump from prokaryotic to eukaryotic is far more intimidating.
  - andrewflnr 8y ago
    That's actually happened a bunch of times, too. I'm just going to link to a comment I made a while back: https://news.ycombinator.com/item?id=18456049 https://news.ycombinator.com/item?id=18456049 "Diatom-derived plastids" blew my mind.
vichu 8y ago
Not to be too pessimistic, but there's no reason that there should only be one "Great Filter". There could easily be multiple astronomically improbable events barring interstellar civilizations from bearing fruition. It might be just as improbable for unicellular life to form as it is for unicellular life to beget multicellular life, so on and so forth.
- devoply 8y ago
  The great filter exists at all times as cited by the fact that the longevity of a species does not guarantee their future survival. All life may die off at any time.
- bduerst 8y ago
  Or even reason to assume that exobiotic life is cellular, and needed to jump from singular to multi-cellular structures like ours did on this planet.
  - andrewflnr 8y ago
    I mean, in principle, but that's probably like assuming that exobiology is carbon based. Carbon and cells are both really super useful.

dukoid 8y ago

Is it really that much of a paradox? - "Metallicity": We probably need a recent / "Population I" star, i.e. it' s probably unlikely that there can be civilizations much older than us (in astronomical dimensions): https://en.wikipedia.org/wiki/Stellar_population#Population_I_stars https://en.wikipedia.org/wiki/Stellar_population#Population_... - In 1.1 billion years from now, the Sun will be 10% brighter than it is today, and this increase in luminosity will also mean an increase in heat energy, which Earth’s atmosphere will absorb. This will trigger a moist greenhouse effect here on Earth that is similar to the runaway warming that turned Venus into the hellish environment we see there today. So we have appeared only after 80% of the "usable" life span of our star has already been over -- a window that might be easy to miss (an larger stars burn even faster)

est31 8y ago
You don't need an astronomically old civilization for it to have galaxy-wide impact. Already a "few" million years should be enough to colonize a dead-except-for-you galaxy.

azernik 8y ago

One of the interesting ones I've heard talk about lately is the "interstellar travel" step - Earth is on the lower end of the size range for rocky planets that can support an atmosphere and magnetic field to shield surface life from radiation. And because of the tyranny of the rocket equation, life developing on larger rocky planets may have a much harder time reaching orbit. A good demo video: https://www.youtube.com/watch?v=amjuJJwI3iM https://www.youtube.com/watch?v=amjuJJwI3iM On a planet with twice the Earth's mass, it would take a larger-than-Saturn-sized rocket to put a Mercury-sized payload into orbit. EDIT: And said Mercury-sized payload would have to spend more of its mass on heat shielding than the human Mercury capsule if it's intended to come back down.

SimbaOnSteroids 8y ago
Yes but the rocket equation wouldn't stop intelligent species from going "loud" with radio signals.
- akiselev 8y ago
  The rocket equation itself, no, but the planet mass would also have drastic effects on the evolution of species. On our planet, high density fibrous plants like trees have an advantage when it comes to access to the sun but what if on a bigger planet, that advantage goes to plants than can emit a spidersilk-like material to float on the wind in colonies? There goes a practically infinitely renewable building material that can be used for almost anything until the industrial age. How can a civilization get to the electronic age when they spend all their time between extinction events hauling rocks and mining ores to build 2 story dwellings? There's just so many unknowns.
  - fsloth 8y ago
    Not only dwellings but fuel as well. I mean, if you don't have trees how are you going to invent fire... Some people consider cooking a critical step in our evolution (cooking enables harvesting more calories from food). With no good fuel available cooking could also be ... off the menu.

taneq 8y ago

Someone evolved a multicellular yeast with a similar approach back in 2011 or so. They used centrifuging to select for larger 'clumps' of yeast, rather than a predator to eat the smaller ones, but still pretty similar. https://www.newscientist.com/article/mg21028184-300-lab-yeast-make-evolutionary-leap-to-multicellularity/ https://www.newscientist.com/article/mg21028184-300-lab-yeas...

DavidSJ 8y ago

Yes, although keep in mind we already knew of three independent evolutions of multicellularity — animals, plants, and fungi — so it arguably couldn’t be an improbable enough transition to qualify for great filter status.

EamonnMR 8y ago
Don't forget the humble Volvox! https://en.m.wikipedia.org/wiki/Volvox https://en.m.wikipedia.org/wiki/Volvox