13 ms·

The prospect and opportunity of rogue planets is fascinating to me. So I'm firmly in the camp that the speed of light is a hard limit in the Universe. Any talk

by cletus 5y ago

The prospect and opportunity of rogue planets is fascinating to me. So I'm firmly in the camp that the speed of light is a hard limit in the Universe. Any talk of wormholes, FTL and space folding just seems like wishful thinking and the product of not understanding the domain of functions (eg putting negative values into mass or energy). Additionally there's macro evidence to this speed limit because if it wasn't a limit it would make the likelihood of encountering spacefaring civilizations that much more likely. So given this, it seems like traveling to other stars requires some form of generational ship. And that seems like a problem because the energy required is massive and that's even before you get into issues of having reaction mass. There are workarounds for this (eg space laser propulsion) but the problems seem... significant. So, rogue planets. I wonder if the first vessel for interstellar travel will in fact be some largish rogue body that visits the Solar System. Even something 100km wide will contain a wealth of raw materials that would otherwise be prohibitively expensive to accelerate to interstellar speeds. And sure it might take 10,000 years or more for such a body to travel to a nearby star but there's really not a lot of difference between several centuries and 10,000 years. What's more, such travelers could likely seed other rogue bodies they encounter along the way. Could this be the initial vector of interstellar colonization? As an aside, George RR Martin 40+ years ago wrote a book called Dying of the Light. I really enjoyed it just for the concept. In this book there are so-called Festival worlds. These are worlds that wander between systems. When they approach stars they get sufficiently warm and thaw out and may have oceans and atmospheres in that time. People would build cities in that time knowing it was all temporary.

eloff 5y ago
What's the point of interstellar colonization? It's possible that will never be interesting to us given the expense, time, and hardships involved. We have more than enough space and resources in this solar system to support north of a trillion humans if we start building space habitats. So even if we start procreating again after our population is predicted to stabilize, we won't run out of room here very easily. My feeling is our digital worlds will get so engrossing we will turn our attention inwards rather than outwards. I don't think that lends itself to either population growth or interstellar colonization. If intelligent civilization is sufficiently rare, that could easily explain the Fermi paradox. They're out there, just too far away and too uninterested in expansion for us to meet.
- shkkmo 5y ago
  I see two major dynamics that could drive interstellar colonization: 1) Eccentricity and Boredom: I think that with a solar system population in the trillions, you will inevitably have a sufficient population of eccentrics to eventually launch generational ships. This is especially likely if humanity survivea long enough for the lifetime our own sun to present a realistic limit on the survival of the species. 2) Eccentricity and Freedom: The major advantage of interstellar colonization is distance from dominant power structures in the solar sytem. I find it quite possible that there could be societies that view fleeing the solar system as their only path to survival as a cultural unit.
  - Sanzig 5y ago
    One of the interesting consequences of interstellar colonization in a universe without FTL travel or communication (which, by all indications, appears to be our universe) is the sheer amount of cultural diversity it would create. Even adjacent systems would have communications round-trip times on the order of single-digit years, and depending how far apart desirable systems for colonization are it could even conceivably be decades of round-trip comms lag to the nearest inhabited system. Centralization becomes impossible, and star systems would have only very weak cultural impact on their neighbors.
    - shkkmo 5y ago
      Interstellar trade of physical goods is quite impractical without FTL. If there is interstellar travel for non-colonization purposes it seems like the primary goal would be to enable low-latency communication to compensate for semantic/cultural drift that could interfere with the efficacy of the high latency communcations.
      - mikro2nd 5y ago
        It seems to me that interstellar trade -- with or without FTL -- is quite unlikely. I wrote some thoughts on this about a year ago, (https://one.mikro2nd.net/2021/07/interstellar/ https://one.mikro2nd.net/2021/07/interstellar/) but tl;dr: If your society is capable of marshalling the resources/energy necessary for interstellar travel in the first place, you have most likely, of necessity, solved the problem of getting more resources. War seems slightly more likely because "ideology". Ultimately I think my notion is quite similar to yours: that the primary exchanges would be culture (art, music, fashions, language, rites,...) so the things for which we want "communication".
shkkmo 5y ago
The most likely form of non-generational inerstellar travel is finding high efficiency methods to accelerate ships to high relatavistic speeds so that time dilation reduces the on-ship time to sub-generation scales.
- cletus 5y ago
  This sounds appealing but there are a couple of major problems. The first is that you have to get to a significant percentage of light speed for this to manifest itself. Even at 0.95c time is only traveling at 1/3 of normal speed [1]. Second, the energy cost for this is truly mind-boggling. Doing so when you carry the fuel seems highly impractical. The best bet are laser highways [2]. But, you need to build that first. The upper limit of laser propulsion isn't really high enough for that level of time dilation. Third, traveling at these speeds makes any potential impact within even a speck of dust potentially fatal. Lastly, fun fact: such a ship actually needs to be aerodynamic. Why? Above 0.95c the drag of hydrogen atoms in the interstellar medium will start to slow you down. [1]: https://www.fourmilab.ch/cship/timedial.html https://www.fourmilab.ch/cship/timedial.html [2]: https://www.youtube.com/watch?v=oDR4AHYRmlk https://www.youtube.com/watch?v=oDR4AHYRmlk
  - Myto 5y ago
    You could get to the nearest star in a few years and to the other side of the galaxy well within a human lifetime with "just" constant 1 g acceleration. Obviously this is far from easy but it doesn't seem like it is necessarily out of reach given a few thousand more years of continued technological development.
    - actually_a_dog 5y ago
      Yes, and there are at least 76 stars (i.e. potentially interesting destinations) within 100 light years of us [0]. So, assuming you can set an arbitrary course at 0.95c, and decelerate without turning the humans inside your ship to organic goo, you can reach quite a few interesting places. --- [0]: http://www.solstation.com/stars3/100-as.htm http://www.solstation.com/stars3/100-as.htm
blacksmith_tb 5y ago
Hitching a ride on a fast-moving extrasolar object passing through sounds good, though it seems like finding one going the right direction (and with enough time to get aboard) would be tricky. I suppose once you landed on it you could try and alter its course with mass drivers, but of course the more massive it was, the harder that would be.
- actually_a_dog 5y ago
  If such a rogue planet were the result of ejection from its previous planetary system, I wouldn't expect that its speed would much exceed its previous orbital velocity in terms of order of magnitude. For reference, the orbital velocity of Mercury is about 60km/s [0], which is about 130,000 mph, or 2e-4*c. We'd certainly notice something as big as a planet coming at us when it's at around the same distance as the Oort cloud, which NASA says lies at a distance of at least 2000 AU [1], or 3e12 km. Since it would take almost 1600 years to travel 3e12 km at 60km/s, I would say we'd have a fair amount of preparation time, even if my estimate for the body's speed were off by a factor of 15. ;-) As for choosing your course, I would say if a rogue planet is about to enter the Solar System, beggars can't be choosers. What I find more interesting is that in order for people to live on or near such a planet, it would almost have to have enough of its own internal heat to create temperatures suitable for life. So, you're almost certainly not looking at a rocky planet with a surface. Therefore, you'd want to design your habitat to orbit or exist within the atmosphere of a gas giant. To my knowledge, there hasn't been any serious proposal for such a habitat, and I'm unaware of the sci-fi perspective on this issue. Of course, the other issue is that at 2e-4*c, you're not going anywhere very fast. :P --- [0]: https://nssdc.gsfc.nasa.gov/planetary/factsheet/mercuryfact.html https://nssdc.gsfc.nasa.gov/planetary/factsheet/mercuryfact.... [1]: https://solarsystem.nasa.gov/solar-system/oort-cloud/overview/ https://solarsystem.nasa.gov/solar-system/oort-cloud/overvie...
avaldes 5y ago
> As an aside, George RR Martin 40+ years ago wrote a book called Dying of the Light. I really enjoyed it just for the concept. In this book there are so-called Festival worlds. These are worlds that wander between systems. When they approach stars they get sufficiently warm and thaw out and may have oceans and atmospheres in that time. People would build cities in that time knowing it was all temporary. Wow so this could be the explanation for erratic seasons of unpredictable duration in ASOIAF?
- InitialLastName 5y ago
  Everything about ASOIAF can be explained by George RR Martin's long career as a military science fiction author. How else could one be free to build a medieval fantasy world so unburdened by historical realism?
  - the_af 5y ago
    Which long career as a military science fiction writer? I admit aside ASOIAF I haven't read much GRRM -- his awesome Sandkings short story, and his collaboration with Lisa Tuttle, Windhaven, and I'm aware of some of his horror/fantasy fiction. Checking on Wikipedia I don't see a lot of military scifi in the list...
    - exhilaration 5y ago
      Thank you, Sandkings was great!
- kzrdude 5y ago
  There is no explanation for the erratic seasons. GRRM (just like any storyteller) creates mystery and interest in his world and fills in the details that are required, and not so many of those that are not. This is something he is very aware of. He will tell you that like any intriguing medieval world map, his world map also has tall tales, mysteries and stories about foreign countries, big monsters and weird men, lining the edge of the map.
colordrops 5y ago
I was under the (false?) impression that most physicists are on board with wormholes being a real and possible phenomenon.
- ripply 5y ago
  It requires negative energy in current theoretical physics, which is what OP is talking about, we have no idea if that will ever actually be possible, its wishful thinking at this point.
  - colordrops 5y ago
    Ok, but that isn't addressing my comment. Most people aren't qualified to evaluate the cutting edge of modern physics. I'm wondering what the experts consensus is, not anonymous internet strangers. Why should I take your word over the world's best physicists?
perl4ever 5y ago
There was also: https://en.wikipedia.org/wiki/A_Pail_of_Air https://en.wikipedia.org/wiki/A_Pail_of_Air "they maintain a breathable atmosphere by periodically retrieving pails of frozen oxygen to thaw over a fire"
perl4ever 5y ago
>prohibitively expensive to accelerate to interstellar speeds. But if it's on a hyperbolic trajectory, then it would be just as hard to get to it as to escape the solar system, no? I wonder what the theoretical distribution of speeds (relative to Earth) of random interstellar debris would be.
tbabb 5y ago
It seems unlikely that we would try to colonize other star systems by sending meat there— meat doesn't keep well over the necessary time scales. It seems a better plan would be to send artificial intelligence which can remain dormant for hundreds or thousands of years. A planet could be "colonized" by building a data center on it and then running a detailed simulation of a habitable planet. In fact, that would open up far more worlds to colonization, because it substantially loosens the requirements for habitability. Or if a simulation truly isn't good enough, then an AI could at least bootstrap a biosphere.
grishka 5y ago
It always creeps me out when someone assumes that people will keep aging and dying in the future, including very far into the future, and would thus need "generational ships" despite all scientific advancement required to make such ships possible in the first place. Right now we're standing on the verge of ending aging. It won't be much longer until it becomes optional.

by cletus 5y ago

eloff 5y ago

What's the point of interstellar colonization? It's possible that will never be interesting to us given the expense, time, and hardships involved. We have more than enough space and resources in this solar system to support north of a trillion humans if we start building space habitats. So even if we start procreating again after our population is predicted to stabilize, we won't run out of room here very easily. My feeling is our digital worlds will get so engrossing we will turn our attention inwards rather than outwards. I don't think that lends itself to either population growth or interstellar colonization. If intelligent civilization is sufficiently rare, that could easily explain the Fermi paradox. They're out there, just too far away and too uninterested in expansion for us to meet.

shkkmo 5y ago
I see two major dynamics that could drive interstellar colonization: 1) Eccentricity and Boredom: I think that with a solar system population in the trillions, you will inevitably have a sufficient population of eccentrics to eventually launch generational ships. This is especially likely if humanity survivea long enough for the lifetime our own sun to present a realistic limit on the survival of the species. 2) Eccentricity and Freedom: The major advantage of interstellar colonization is distance from dominant power structures in the solar sytem. I find it quite possible that there could be societies that view fleeing the solar system as their only path to survival as a cultural unit.
- Sanzig 5y ago
  One of the interesting consequences of interstellar colonization in a universe without FTL travel or communication (which, by all indications, appears to be our universe) is the sheer amount of cultural diversity it would create. Even adjacent systems would have communications round-trip times on the order of single-digit years, and depending how far apart desirable systems for colonization are it could even conceivably be decades of round-trip comms lag to the nearest inhabited system. Centralization becomes impossible, and star systems would have only very weak cultural impact on their neighbors.
  - shkkmo 5y ago
    Interstellar trade of physical goods is quite impractical without FTL. If there is interstellar travel for non-colonization purposes it seems like the primary goal would be to enable low-latency communication to compensate for semantic/cultural drift that could interfere with the efficacy of the high latency communcations.
    - mikro2nd 5y ago
      It seems to me that interstellar trade -- with or without FTL -- is quite unlikely. I wrote some thoughts on this about a year ago, (https://one.mikro2nd.net/2021/07/interstellar/ https://one.mikro2nd.net/2021/07/interstellar/) but tl;dr: If your society is capable of marshalling the resources/energy necessary for interstellar travel in the first place, you have most likely, of necessity, solved the problem of getting more resources. War seems slightly more likely because "ideology". Ultimately I think my notion is quite similar to yours: that the primary exchanges would be culture (art, music, fashions, language, rites,...) so the things for which we want "communication".

shkkmo 5y ago

The most likely form of non-generational inerstellar travel is finding high efficiency methods to accelerate ships to high relatavistic speeds so that time dilation reduces the on-ship time to sub-generation scales.

cletus 5y ago
This sounds appealing but there are a couple of major problems. The first is that you have to get to a significant percentage of light speed for this to manifest itself. Even at 0.95c time is only traveling at 1/3 of normal speed [1]. Second, the energy cost for this is truly mind-boggling. Doing so when you carry the fuel seems highly impractical. The best bet are laser highways [2]. But, you need to build that first. The upper limit of laser propulsion isn't really high enough for that level of time dilation. Third, traveling at these speeds makes any potential impact within even a speck of dust potentially fatal. Lastly, fun fact: such a ship actually needs to be aerodynamic. Why? Above 0.95c the drag of hydrogen atoms in the interstellar medium will start to slow you down. [1]: https://www.fourmilab.ch/cship/timedial.html https://www.fourmilab.ch/cship/timedial.html [2]: https://www.youtube.com/watch?v=oDR4AHYRmlk https://www.youtube.com/watch?v=oDR4AHYRmlk
- Myto 5y ago
  You could get to the nearest star in a few years and to the other side of the galaxy well within a human lifetime with "just" constant 1 g acceleration. Obviously this is far from easy but it doesn't seem like it is necessarily out of reach given a few thousand more years of continued technological development.
  - actually_a_dog 5y ago
    Yes, and there are at least 76 stars (i.e. potentially interesting destinations) within 100 light years of us [0]. So, assuming you can set an arbitrary course at 0.95c, and decelerate without turning the humans inside your ship to organic goo, you can reach quite a few interesting places. --- [0]: http://www.solstation.com/stars3/100-as.htm http://www.solstation.com/stars3/100-as.htm

blacksmith_tb 5y ago

Hitching a ride on a fast-moving extrasolar object passing through sounds good, though it seems like finding one going the right direction (and with enough time to get aboard) would be tricky. I suppose once you landed on it you could try and alter its course with mass drivers, but of course the more massive it was, the harder that would be.

actually_a_dog 5y ago
If such a rogue planet were the result of ejection from its previous planetary system, I wouldn't expect that its speed would much exceed its previous orbital velocity in terms of order of magnitude. For reference, the orbital velocity of Mercury is about 60km/s [0], which is about 130,000 mph, or 2e-4*c. We'd certainly notice something as big as a planet coming at us when it's at around the same distance as the Oort cloud, which NASA says lies at a distance of at least 2000 AU [1], or 3e12 km. Since it would take almost 1600 years to travel 3e12 km at 60km/s, I would say we'd have a fair amount of preparation time, even if my estimate for the body's speed were off by a factor of 15. ;-) As for choosing your course, I would say if a rogue planet is about to enter the Solar System, beggars can't be choosers. What I find more interesting is that in order for people to live on or near such a planet, it would almost have to have enough of its own internal heat to create temperatures suitable for life. So, you're almost certainly not looking at a rocky planet with a surface. Therefore, you'd want to design your habitat to orbit or exist within the atmosphere of a gas giant. To my knowledge, there hasn't been any serious proposal for such a habitat, and I'm unaware of the sci-fi perspective on this issue. Of course, the other issue is that at 2e-4*c, you're not going anywhere very fast. :P --- [0]: https://nssdc.gsfc.nasa.gov/planetary/factsheet/mercuryfact.html https://nssdc.gsfc.nasa.gov/planetary/factsheet/mercuryfact.... [1]: https://solarsystem.nasa.gov/solar-system/oort-cloud/overview/ https://solarsystem.nasa.gov/solar-system/oort-cloud/overvie...

avaldes 5y ago

> As an aside, George RR Martin 40+ years ago wrote a book called Dying of the Light. I really enjoyed it just for the concept. In this book there are so-called Festival worlds. These are worlds that wander between systems. When they approach stars they get sufficiently warm and thaw out and may have oceans and atmospheres in that time. People would build cities in that time knowing it was all temporary. Wow so this could be the explanation for erratic seasons of unpredictable duration in ASOIAF?

InitialLastName 5y ago
Everything about ASOIAF can be explained by George RR Martin's long career as a military science fiction author. How else could one be free to build a medieval fantasy world so unburdened by historical realism?
- the_af 5y ago
  Which long career as a military science fiction writer? I admit aside ASOIAF I haven't read much GRRM -- his awesome Sandkings short story, and his collaboration with Lisa Tuttle, Windhaven, and I'm aware of some of his horror/fantasy fiction. Checking on Wikipedia I don't see a lot of military scifi in the list...
  - exhilaration 5y ago
    Thank you, Sandkings was great!
kzrdude 5y ago
There is no explanation for the erratic seasons. GRRM (just like any storyteller) creates mystery and interest in his world and fills in the details that are required, and not so many of those that are not. This is something he is very aware of. He will tell you that like any intriguing medieval world map, his world map also has tall tales, mysteries and stories about foreign countries, big monsters and weird men, lining the edge of the map.

colordrops 5y ago

I was under the (false?) impression that most physicists are on board with wormholes being a real and possible phenomenon.

ripply 5y ago
It requires negative energy in current theoretical physics, which is what OP is talking about, we have no idea if that will ever actually be possible, its wishful thinking at this point.
- colordrops 5y ago
  Ok, but that isn't addressing my comment. Most people aren't qualified to evaluate the cutting edge of modern physics. I'm wondering what the experts consensus is, not anonymous internet strangers. Why should I take your word over the world's best physicists?

perl4ever 5y ago

There was also: https://en.wikipedia.org/wiki/A_Pail_of_Air https://en.wikipedia.org/wiki/A_Pail_of_Air "they maintain a breathable atmosphere by periodically retrieving pails of frozen oxygen to thaw over a fire"

perl4ever 5y ago

>prohibitively expensive to accelerate to interstellar speeds. But if it's on a hyperbolic trajectory, then it would be just as hard to get to it as to escape the solar system, no? I wonder what the theoretical distribution of speeds (relative to Earth) of random interstellar debris would be.

tbabb 5y ago

It seems unlikely that we would try to colonize other star systems by sending meat there— meat doesn't keep well over the necessary time scales. It seems a better plan would be to send artificial intelligence which can remain dormant for hundreds or thousands of years. A planet could be "colonized" by building a data center on it and then running a detailed simulation of a habitable planet. In fact, that would open up far more worlds to colonization, because it substantially loosens the requirements for habitability. Or if a simulation truly isn't good enough, then an AI could at least bootstrap a biosphere.

grishka 5y ago

It always creeps me out when someone assumes that people will keep aging and dying in the future, including very far into the future, and would thus need "generational ships" despite all scientific advancement required to make such ships possible in the first place. Right now we're standing on the verge of ending aging. It won't be much longer until it becomes optional.