7 ms·

Cosmic voids

80 points by CarolineW 9y ago

yummybear 9y ago
Horrifyingly lonesome - almost complete sensory deprivation. It would be interesting to experience though.
- pc86 9y ago
  If you were here in a space suit, would you be able to see anything at all? I would think not, but am not sure.
  - idlewords 9y ago
    The linked article answers this. If you had no other sources of light, so that your eyes could fully acclimate, you might be able to see the faintest smudges if there were galaxies within 70 million light years.
valarauca1 9y ago
The existential loneliness of a void is weird. We're privileged to look up at the stars and ask who's out there. A species living in a large void would have to develop extremely (compariable to modern humans) technology to ever prove there was another galaxy within the universe.
- pavel_lishin 9y ago
  As the universe expands, there will come a time when no feasible technology will be able to tell you that there's anything outside of your galaxy. (Maybe if you wait long enough, there won't be anything outside of your solar system.)
  - bdamm 9y ago
    That's an interesting idea. I knew the universe is expanding relative to galaxies, but I didn't realize that the expansion of the universe was overcoming gravity within the scope of a galaxy. Does this also mean that the distance between planets within a solar system will increase? Is the rate of expansion more than or less than the expansion of the sun's diameter? Does this mean that the distance from the Earth to the moon is increasing, and does it mean the planet itself is expanding? Is the expansion of the universe a destabilizing effect on orbital mechanics?
    - ajross 9y ago
      The dark energy phenomenon driving accelerated expansion is poorly described by theory, so predictions don't mean much. But yes: if expansion continues accelerating as it has been then eventually it will overpower intra-galaxy gravitation, then intra-system, and eventually intra--celestial-bodies and so on. Eventually planets and stars (and atoms and protons!) would be ripped apart.
      - pdonis 9y ago
        > if expansion continues accelerating as it has been then eventually it will overpower intra-galaxy gravitation, then intra-system, and eventually intra--celestial-bodies and so on. Eventually planets and stars (and atoms and protons!) would be ripped apart This is not true for dark energy, i.e., for accelerated expansion per se. It is only true for a "Big Rip" scenario in which the acceleration itself accelerates. The "stuff" that drives such a scenario is called "phantom energy" and such a scenario is currently believed to be extremely low probability.
    - Santosh83 9y ago
      IIRC the expansion is accelerating according to the best observations. Which means in the far future galaxies should find themselves in an endless sea of voids. Eventually stars, planets, living beings and atoms will all get torn apart unless something counters the accelerating expansion.
      - pdonis 9y ago
- XorNot 9y ago
  Imagining how exciting the first galaxy detection would be though is quite a thing.
- p1mrx 9y ago
  On the other hand, the probability of life arising in the middle of a void seems relatively small. We are made of dead stars.
- booleandilemma 9y ago
  This reminds me of Douglas Adams' Krikkiters, whose home planet is completely surrounded by black dust. It blocks out everything in the sky and so they had no concept of anything at all existing beyond their world. http://aliens.wikia.com/wiki/Krikkiter http://aliens.wikia.com/wiki/Krikkiter
  - soVeryTired 9y ago
    It'll have to go...
pavel_lishin 9y ago
A not-really-spoiler-alert for Iain M. Banks' "Against a Dark Background", whose title turns out to be a bit of foreshadowing itself: The planet system where the novel takes place is extragalactic, surrounded by no stars. If I remember correctly, they can see their nearby galaxy, but nothing nearer.
- blacksmith_tb 9y ago
  An extrasolar (if not extra-galactic) planet is a subplot in Becky Chambers' kickstarted[1] _The Long Way to a Small Angry Planet_[2], too. 1: https://www.kickstarter.com/projects/beckychambers/the-long-way-to-a-small-angry-planet/updates https://www.kickstarter.com/projects/beckychambers/the-long-... 2: http://www.tor.com/2015/08/14/excerpts-the-long-way-to-a-small-angry-planet-becky-chambers/ http://www.tor.com/2015/08/14/excerpts-the-long-way-to-a-sma...
  - pavel_lishin 9y ago
    I thought the titular planet was just near the core, not extra-galactic? Or am I forgetting one?
Santosh83 9y ago
I think we underestimate the importance of a starry sky for the development of intelligence. A species looking up at complete blackness will probably never develop higher reasoning or curiosity.
- jimlawruk 9y ago
  Due to light pollution, many people on Earth rarely see a starry sky.
- Raphmedia 9y ago
  Would it? There are plenty of curiosity to be had on the ground, in the air and under water. Birds flying, insects digging, fishes swimming. Sure, they might not feel the need to visit space if they had no stars, no moon and no sun but who knows? They might end up going there anyway due to population and create their own superstructures.
  - Santosh83 9y ago
    The existence of stars gives us (humans at least) an idea that we actually live in a vast and varied universe and that I think is crucial psychological motivation to push boundaries and explore. If we lived within a void and believed that our one planet (and its star) were the universe, we would be content to develop only those skill & intelligence needed to survive on the planet. It might stagnate after a point. Of course, even a small telescope would reveal the distant galaxies, but would a hypothetical intelligent species get to that point at all? And even if they could glimpse the distant galaxies, what could conceivably motivate them to develop space travel? Am just wondering aloud. Astronomy was (and is) a pretty fundamental pillar of our scientific development and all that it has brought us. An inky black sky would have interesting effects upon nascent, intelligent species.
    - Raphmedia 9y ago
      The Hitchhiker's Guide to the Galaxy actually explored the concept. One planet is in a dust cloud. The sky was completely black, and thus the people of that planet led insular lives and never realised the existence of the Universe. They eventually built a small ship and managed to exit the dust cloud. Upon first witnessing the glory and splendor of the Universe, they casually, whimsically, decided to destroy it, remarking, "It'll have to go." The race changed from a peaceful one to the most violent warfaring race of the galaxy.
CiPHPerCoder 9y ago
I found the video linked at the bottom interesting too: https://www.youtube.com/watch?v=rENyyRwxpHo https://www.youtube.com/watch?v=rENyyRwxpHo I'd never heard of Laniakea before.
gmisra 9y ago
These voids change moving up the distance scale - while our star system is visibly not inside a void, there is evidence that the Milky Way is inside a galactic-scale void. http://news.wisc.edu/celestial-boondocks-study-supports-the-idea-that-we-live-in-a-void/ http://news.wisc.edu/celestial-boondocks-study-supports-the-... https://www.universetoday.com/135954/largest-scales-milky-way-galaxy-middle-nowhere/ https://www.universetoday.com/135954/largest-scales-milky-wa...
205guy 9y ago
I found the answer disappointing because the argument has a huge hole in it: it discounts the atmosphere. The article says the farthest objects earth-based naked-eye observations can detect are ~70 million light years away, so if you're in space in the middle of a billion light year void, you won't see anything. But if the atmosphere has just one order of magnitude attenuation (or rather you could see 10 times further without it), then maybe you could see to the 500 million light year edge of your void bubble. That's what bothers me about these pseudo-scientific columns: they aren't rigorous and the reader doesn't know it. In this particular case, the author even changed the reader's question, and then didn't even give a satisfactory answer, just wanted to write about "cool" things.

Cosmic voids

80 points by CarolineW 9y ago

yummybear 9y ago

Horrifyingly lonesome - almost complete sensory deprivation. It would be interesting to experience though.

pc86 9y ago
If you were here in a space suit, would you be able to see anything at all? I would think not, but am not sure.
- idlewords 9y ago
  The linked article answers this. If you had no other sources of light, so that your eyes could fully acclimate, you might be able to see the faintest smudges if there were galaxies within 70 million light years.

valarauca1 9y ago

The existential loneliness of a void is weird. We're privileged to look up at the stars and ask who's out there. A species living in a large void would have to develop extremely (compariable to modern humans) technology to ever prove there was another galaxy within the universe.

pavel_lishin 9y ago
As the universe expands, there will come a time when no feasible technology will be able to tell you that there's anything outside of your galaxy. (Maybe if you wait long enough, there won't be anything outside of your solar system.)
- bdamm 9y ago
  That's an interesting idea. I knew the universe is expanding relative to galaxies, but I didn't realize that the expansion of the universe was overcoming gravity within the scope of a galaxy. Does this also mean that the distance between planets within a solar system will increase? Is the rate of expansion more than or less than the expansion of the sun's diameter? Does this mean that the distance from the Earth to the moon is increasing, and does it mean the planet itself is expanding? Is the expansion of the universe a destabilizing effect on orbital mechanics?
  - ajross 9y ago
    The dark energy phenomenon driving accelerated expansion is poorly described by theory, so predictions don't mean much. But yes: if expansion continues accelerating as it has been then eventually it will overpower intra-galaxy gravitation, then intra-system, and eventually intra--celestial-bodies and so on. Eventually planets and stars (and atoms and protons!) would be ripped apart.
    - pdonis 9y ago
      > if expansion continues accelerating as it has been then eventually it will overpower intra-galaxy gravitation, then intra-system, and eventually intra--celestial-bodies and so on. Eventually planets and stars (and atoms and protons!) would be ripped apart This is not true for dark energy, i.e., for accelerated expansion per se. It is only true for a "Big Rip" scenario in which the acceleration itself accelerates. The "stuff" that drives such a scenario is called "phantom energy" and such a scenario is currently believed to be extremely low probability.
  - Santosh83 9y ago
    IIRC the expansion is accelerating according to the best observations. Which means in the far future galaxies should find themselves in an endless sea of voids. Eventually stars, planets, living beings and atoms will all get torn apart unless something counters the accelerating expansion.
    - pdonis 9y ago
XorNot 9y ago
Imagining how exciting the first galaxy detection would be though is quite a thing.
p1mrx 9y ago
On the other hand, the probability of life arising in the middle of a void seems relatively small. We are made of dead stars.
booleandilemma 9y ago
This reminds me of Douglas Adams' Krikkiters, whose home planet is completely surrounded by black dust. It blocks out everything in the sky and so they had no concept of anything at all existing beyond their world. http://aliens.wikia.com/wiki/Krikkiter http://aliens.wikia.com/wiki/Krikkiter
- soVeryTired 9y ago
  It'll have to go...

pavel_lishin 9y ago

A not-really-spoiler-alert for Iain M. Banks' "Against a Dark Background", whose title turns out to be a bit of foreshadowing itself: The planet system where the novel takes place is extragalactic, surrounded by no stars. If I remember correctly, they can see their nearby galaxy, but nothing nearer.

blacksmith_tb 9y ago
An extrasolar (if not extra-galactic) planet is a subplot in Becky Chambers' kickstarted[1] _The Long Way to a Small Angry Planet_[2], too. 1: https://www.kickstarter.com/projects/beckychambers/the-long-way-to-a-small-angry-planet/updates https://www.kickstarter.com/projects/beckychambers/the-long-... 2: http://www.tor.com/2015/08/14/excerpts-the-long-way-to-a-small-angry-planet-becky-chambers/ http://www.tor.com/2015/08/14/excerpts-the-long-way-to-a-sma...
- pavel_lishin 9y ago
  I thought the titular planet was just near the core, not extra-galactic? Or am I forgetting one?

Santosh83 9y ago

I think we underestimate the importance of a starry sky for the development of intelligence. A species looking up at complete blackness will probably never develop higher reasoning or curiosity.

jimlawruk 9y ago
Due to light pollution, many people on Earth rarely see a starry sky.
Raphmedia 9y ago
Would it? There are plenty of curiosity to be had on the ground, in the air and under water. Birds flying, insects digging, fishes swimming. Sure, they might not feel the need to visit space if they had no stars, no moon and no sun but who knows? They might end up going there anyway due to population and create their own superstructures.
- Santosh83 9y ago
  The existence of stars gives us (humans at least) an idea that we actually live in a vast and varied universe and that I think is crucial psychological motivation to push boundaries and explore. If we lived within a void and believed that our one planet (and its star) were the universe, we would be content to develop only those skill & intelligence needed to survive on the planet. It might stagnate after a point. Of course, even a small telescope would reveal the distant galaxies, but would a hypothetical intelligent species get to that point at all? And even if they could glimpse the distant galaxies, what could conceivably motivate them to develop space travel? Am just wondering aloud. Astronomy was (and is) a pretty fundamental pillar of our scientific development and all that it has brought us. An inky black sky would have interesting effects upon nascent, intelligent species.
  - Raphmedia 9y ago
    The Hitchhiker's Guide to the Galaxy actually explored the concept. One planet is in a dust cloud. The sky was completely black, and thus the people of that planet led insular lives and never realised the existence of the Universe. They eventually built a small ship and managed to exit the dust cloud. Upon first witnessing the glory and splendor of the Universe, they casually, whimsically, decided to destroy it, remarking, "It'll have to go." The race changed from a peaceful one to the most violent warfaring race of the galaxy.

CiPHPerCoder 9y ago

I found the video linked at the bottom interesting too: https://www.youtube.com/watch?v=rENyyRwxpHo https://www.youtube.com/watch?v=rENyyRwxpHo I'd never heard of Laniakea before.

gmisra 9y ago

These voids change moving up the distance scale - while our star system is visibly not inside a void, there is evidence that the Milky Way is inside a galactic-scale void. http://news.wisc.edu/celestial-boondocks-study-supports-the-idea-that-we-live-in-a-void/ http://news.wisc.edu/celestial-boondocks-study-supports-the-... https://www.universetoday.com/135954/largest-scales-milky-way-galaxy-middle-nowhere/ https://www.universetoday.com/135954/largest-scales-milky-wa...

205guy 9y ago

I found the answer disappointing because the argument has a huge hole in it: it discounts the atmosphere. The article says the farthest objects earth-based naked-eye observations can detect are ~70 million light years away, so if you're in space in the middle of a billion light year void, you won't see anything. But if the atmosphere has just one order of magnitude attenuation (or rather you could see 10 times further without it), then maybe you could see to the 500 million light year edge of your void bubble. That's what bothers me about these pseudo-scientific columns: they aren't rigorous and the reader doesn't know it. In this particular case, the author even changed the reader's question, and then didn't even give a satisfactory answer, just wanted to write about "cool" things.