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And frightening. Such photos really bring home the Great Silence. All of those specks which are entire galaxies, and not the single slightest sign of intelligen

by gwern 6y ago

And frightening. Such photos really bring home the Great Silence. All of those specks which are entire galaxies, and not the single slightest sign of intelligent life anywhere, ever. The marbles roll on just as they have for billions and billions of years and will go on rolling for billions to come, dead pieces of inert matter tracing out their gravitational trajectories and burning as predicted.

myself248 6y ago
Could I say that it's also hopeful in a way, that nobody more violent than us seems to have emerged?
- newen 6y ago
  Well, if they have, they would probably have bombed their civilizations into extinction already.
- bluGill 6y ago
  No, the speed of light is too slow for them to do anything about us.
krapp 6y ago
>All of those specks which are entire galaxies, and not the single slightest sign of intelligent life anywhere, ever. You say that as if we could tell with any certainty, at that scale. There could be interstellar civilizations spanning several of those galaxies and uncountable intelligent civilizations that simply never pursued space travel or the constant accelerated curve of energy consumption and colonization we assume they would, only because we ourselves would. We wouldn't know, we don't even really know what we're looking for, and the universe is so vast that even if we did, we'd be all but certain to blink and miss it.
- bluGill 6y ago
  It isn't even clear that the pursuit of colonization we want to pursue is even possible. It takes a lot of energy to do those things and there are limits to how much we can safely use. We are already worried about global warming despite not having a colony to support.
- YayamiOmate 6y ago
  Yea, but they would have to blink a significant portion of their galaxy for us to notice. The top of our capabilities is indirect planet discovery. So alien civilization would need to affect ceartain stars on a scale that a planet does and make it look not natural, like prime number periods or something.
gregmac 6y ago
This is like being in a plane at cruising altitude, looking down at the ocean, and declaring there's zero signs of life, so the ocean must be dead.
- pixl97 6y ago
  Whales would be visible, along with all the life chemicals, so the analogy isnt that great.
  - jstanley 6y ago
    I've flown in planes a handful of times, looked down at the ocean on plenty of opportunities, and never observed any whales. I'd say the analogy is perfectly great.
    - Ma8ee 6y ago
      If the water was as transparent as space, whales and large schools of fish would certainly be apparent.
      - saagarjha 6y ago
        Space isn't quite transparent, and a closer analogy would be to ask if you can spot bacteria and other microorganisms because something sentient the size of a whale "scaled up to space" would be unrecognizable as such to us.
        Ma8ee 6y ago
        > Space isn't quite transparent On Earth scale it is for all practical purposes.
      - doctor_eval 6y ago
        Space whales!
- gwern 6y ago
graycat 6y ago
Assume we are starting with, IIRC, ballpark 14 billion years since the big bang. Well, to get to life, we have to have chemical elements more than just the hydrogen, helium, and a little lithium that came directly from the big bang. So for carbon, oxygen, ..., iron, have to have some big stars form, burn, and explode. So those galaxies from 12 billion years ago didn't have much time -- ballpark only 2 billion years -- to form the elements of the periodic table. Coming at it from our end, IIRC our planet and solar system are about 5 billion years old. Give it, after the big bang, 4 billion years to the periodic table and another 5 billion years for life. So, that's 9 billion years, 5 billion years ago. So don't expect much in Little Green Men ET from more than 5 billion years ago. Since we started 5 billion years ago, we are ballpark only second generation life in this universe. Net, mostly what's in the Hubble deep field images is too old to have much in life (anything like ours). To have a shot at seeing life, don't look back more than ballpark 5 billion years. Since stars are burning out and the universe is expanding, are we also about the last generation of life? Yup, it's amazing to look back 12 billion years, to see galaxies already there, with quasars and, thus, likely supermassive black holes. Amazing to guess how such big black holes formed so soon. Lots more that's amazing. Still for life, only look back about 5 billion years. Disclosure: I'm not an astronomer!
- imhoguy 6y ago
  > Still for life, only look back about 5 billion years. This contradicts the clue of the article. Sometimes it is worth to step back and try something unordinary, especially in area where our assumptions are so weak - the Universe.
- HoveringOrb 6y ago
  >Since stars are burning out and the universe is expanding, are we also about the last generation of life? Red dwarfs will still be burning a trillion years from now. The flare stars among them will only become more stable with time. I'm not sure what the prospects for interstellar travel will be by then, though.
mensetmanusman 6y ago
Even if we wanted to tell the universe we existed, it would take too much energy to shoot out a strong enough signal. We would have to eat the sun to do that :)

by gwern 6y ago

myself248 6y ago

Could I say that it's also hopeful in a way, that nobody more violent than us seems to have emerged?

newen 6y ago
Well, if they have, they would probably have bombed their civilizations into extinction already.
bluGill 6y ago
No, the speed of light is too slow for them to do anything about us.

krapp 6y ago

>All of those specks which are entire galaxies, and not the single slightest sign of intelligent life anywhere, ever. You say that as if we could tell with any certainty, at that scale. There could be interstellar civilizations spanning several of those galaxies and uncountable intelligent civilizations that simply never pursued space travel or the constant accelerated curve of energy consumption and colonization we assume they would, only because we ourselves would. We wouldn't know, we don't even really know what we're looking for, and the universe is so vast that even if we did, we'd be all but certain to blink and miss it.

bluGill 6y ago
It isn't even clear that the pursuit of colonization we want to pursue is even possible. It takes a lot of energy to do those things and there are limits to how much we can safely use. We are already worried about global warming despite not having a colony to support.
YayamiOmate 6y ago
Yea, but they would have to blink a significant portion of their galaxy for us to notice. The top of our capabilities is indirect planet discovery. So alien civilization would need to affect ceartain stars on a scale that a planet does and make it look not natural, like prime number periods or something.

gregmac 6y ago

This is like being in a plane at cruising altitude, looking down at the ocean, and declaring there's zero signs of life, so the ocean must be dead.

pixl97 6y ago
Whales would be visible, along with all the life chemicals, so the analogy isnt that great.
- jstanley 6y ago
  I've flown in planes a handful of times, looked down at the ocean on plenty of opportunities, and never observed any whales. I'd say the analogy is perfectly great.
  - Ma8ee 6y ago
    If the water was as transparent as space, whales and large schools of fish would certainly be apparent.
    - saagarjha 6y ago
      Space isn't quite transparent, and a closer analogy would be to ask if you can spot bacteria and other microorganisms because something sentient the size of a whale "scaled up to space" would be unrecognizable as such to us.
      - Ma8ee 6y ago
        > Space isn't quite transparent On Earth scale it is for all practical purposes.
    - doctor_eval 6y ago
      Space whales!
gwern 6y ago

graycat 6y ago

Assume we are starting with, IIRC, ballpark 14 billion years since the big bang. Well, to get to life, we have to have chemical elements more than just the hydrogen, helium, and a little lithium that came directly from the big bang. So for carbon, oxygen, ..., iron, have to have some big stars form, burn, and explode. So those galaxies from 12 billion years ago didn't have much time -- ballpark only 2 billion years -- to form the elements of the periodic table. Coming at it from our end, IIRC our planet and solar system are about 5 billion years old. Give it, after the big bang, 4 billion years to the periodic table and another 5 billion years for life. So, that's 9 billion years, 5 billion years ago. So don't expect much in Little Green Men ET from more than 5 billion years ago. Since we started 5 billion years ago, we are ballpark only second generation life in this universe. Net, mostly what's in the Hubble deep field images is too old to have much in life (anything like ours). To have a shot at seeing life, don't look back more than ballpark 5 billion years. Since stars are burning out and the universe is expanding, are we also about the last generation of life? Yup, it's amazing to look back 12 billion years, to see galaxies already there, with quasars and, thus, likely supermassive black holes. Amazing to guess how such big black holes formed so soon. Lots more that's amazing. Still for life, only look back about 5 billion years. Disclosure: I'm not an astronomer!

imhoguy 6y ago
> Still for life, only look back about 5 billion years. This contradicts the clue of the article. Sometimes it is worth to step back and try something unordinary, especially in area where our assumptions are so weak - the Universe.
HoveringOrb 6y ago
>Since stars are burning out and the universe is expanding, are we also about the last generation of life? Red dwarfs will still be burning a trillion years from now. The flare stars among them will only become more stable with time. I'm not sure what the prospects for interstellar travel will be by then, though.

mensetmanusman 6y ago

Even if we wanted to tell the universe we existed, it would take too much energy to shoot out a strong enough signal. We would have to eat the sun to do that :)