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gridloreOn the 6th of October, 1995, the world learned that we were not alone. No, the aliens hadn't shown up, but the first confirmed planet orbiting another star was found. 51 Pegasi b, orbiting a star roughly 50 light years away, changed how we saw the universe.
Because astronomers had been saying for centuries that there was no reason for other stars not to have their own family of planets. But until we found evidence, it was still just a hypothesis. But once we found that first planet, the flood gates opened. Observatories began confirming dozens, then hundreds of "exoplanets" orbiting other stars. Orbital observatories like TESS (Transiting Exoplanet Survey Satellite) are finding more every day. To date, we've confirmed nearly 4,000 planets orbiting other suns.
But there are a few problems for the science-fiction fan dreaming of colonies on strange new worlds. Of these 4,000 worlds, only a tiny fraction might be habitable. Many are super-Earth, much larger and more massive, which would indicate much higher gravity than Earth's 1g. Imagine living on a world where the force of gravity is three times stronger. You weight three times as much, and falls would be bone-shattering. You'd also be breathing air that was thick as soup assuming there was any free oxygen there to begin with. Other worlds have similar issues. So close to their stars that their year lasts less than a week and the sunward face would be molten, or so far out that they are ice-encased balls of dead rock. Not very inviting.
Add in that getting anywhere is a daunting prospect. Our closest neighbor, Proxima Centauri, is 4.244 light years away. That's 2.49489x10^13 miles. Unless we turn everything we know about physics on its head and find a way to cheat lightspeed, getting anywhere is going to be a slog. There is an "effective" speed limit of about 40% of the speed of light with the technology we have now. Any faster, and you start to have real problems with both relativistic effects (your ship gets more massive as it approaches the speed of light) and the random bits of dust and hydrogen you hit start having the impact energy of atomic bombs.
That makes the trip to Proxima Centauri b take about 17 years (ship time, the trip feels a little quicker for those on board due to relativity) which means that that ship needs to be able to support both crew and colonists for a long time. These are known in science-fiction as generation ships, Huge vessels built to carry thousands and support them with a functioning ecosystem. These ships have to be built to last because as the name implies, generations will live and die before the ship reaches its destination. For example, the closest candidate for a twin to Earth is Kepler-186f, which is 500 light years away. With our .4c speed limit, getting there is going to take 2,271 years, ship time. For reference, 2,271 years ago, Ptolemy II Philadelphus was king of Ptolemaic Egypt.
Which raises the question, after untold generations in space, living in an enclosed world, would the settlers choose to leave the home of their families for untold generations to settle a new world? What kinds of cultures would evolve on these ships? Given centuries, it's quite possible that any given generation ship could experience the same cycle of rising and falling, with new religions, new languages, even the possibility that over time the population forgets they are on a ship at all and see the ship as their entire universe.
Even on shorter hauls, even if we figure out how to beat the problems of relativity, the journies are going to take a long time. Tau Ceti, long a favorite of science fiction writers because the star is a close twin to our sun, lies a mere 11.9 light years away. If our transport can boost at 1G acceleration (adding roughly 10m^2 velocity every second) and can make it to .99c, the onboard trip will take a bit over five years for those on the ship. But here's where things get fun. Relativity means that those 5.14 years on the ship happened while 13.7 years passed outside the ship. If you take the same ship from Earth to Kepler-186f, it gets much worse. You have 12 years onboard to practice saying "Hello, my name is" in Keplerian, but 501 years have passed in the non-relativistic universe, and the language has changed beyond recognition.
In this case, I think you would develop a caste of spacers who live their entire lives on their ships and pass through the centuries as ghosts, visiting colonized worlds for trade and passing information. British author Alastair Reynolds has written an entire series, called Revelation Space, around this idea.
Science fiction loves to break the rules. Faster than light travel, magic energy sources that can provide endless power with no input, and fantastic but plausible technologies. Larry Niven also played with the concept with his Léshy Circuit stories, where vast slower than light starships used magnetic scoops to feed their fusion drives with interstellar hydrogen. Sometimes, the story is more interesting with you don't break physics. I should try that.
All travel times were generated at the Relativistic Star Ship Calculator http://convertalot.com/relativistic_star_ship_calculator.html
Because astronomers had been saying for centuries that there was no reason for other stars not to have their own family of planets. But until we found evidence, it was still just a hypothesis. But once we found that first planet, the flood gates opened. Observatories began confirming dozens, then hundreds of "exoplanets" orbiting other stars. Orbital observatories like TESS (Transiting Exoplanet Survey Satellite) are finding more every day. To date, we've confirmed nearly 4,000 planets orbiting other suns.
But there are a few problems for the science-fiction fan dreaming of colonies on strange new worlds. Of these 4,000 worlds, only a tiny fraction might be habitable. Many are super-Earth, much larger and more massive, which would indicate much higher gravity than Earth's 1g. Imagine living on a world where the force of gravity is three times stronger. You weight three times as much, and falls would be bone-shattering. You'd also be breathing air that was thick as soup assuming there was any free oxygen there to begin with. Other worlds have similar issues. So close to their stars that their year lasts less than a week and the sunward face would be molten, or so far out that they are ice-encased balls of dead rock. Not very inviting.
Add in that getting anywhere is a daunting prospect. Our closest neighbor, Proxima Centauri, is 4.244 light years away. That's 2.49489x10^13 miles. Unless we turn everything we know about physics on its head and find a way to cheat lightspeed, getting anywhere is going to be a slog. There is an "effective" speed limit of about 40% of the speed of light with the technology we have now. Any faster, and you start to have real problems with both relativistic effects (your ship gets more massive as it approaches the speed of light) and the random bits of dust and hydrogen you hit start having the impact energy of atomic bombs.
That makes the trip to Proxima Centauri b take about 17 years (ship time, the trip feels a little quicker for those on board due to relativity) which means that that ship needs to be able to support both crew and colonists for a long time. These are known in science-fiction as generation ships, Huge vessels built to carry thousands and support them with a functioning ecosystem. These ships have to be built to last because as the name implies, generations will live and die before the ship reaches its destination. For example, the closest candidate for a twin to Earth is Kepler-186f, which is 500 light years away. With our .4c speed limit, getting there is going to take 2,271 years, ship time. For reference, 2,271 years ago, Ptolemy II Philadelphus was king of Ptolemaic Egypt.
Which raises the question, after untold generations in space, living in an enclosed world, would the settlers choose to leave the home of their families for untold generations to settle a new world? What kinds of cultures would evolve on these ships? Given centuries, it's quite possible that any given generation ship could experience the same cycle of rising and falling, with new religions, new languages, even the possibility that over time the population forgets they are on a ship at all and see the ship as their entire universe.
Even on shorter hauls, even if we figure out how to beat the problems of relativity, the journies are going to take a long time. Tau Ceti, long a favorite of science fiction writers because the star is a close twin to our sun, lies a mere 11.9 light years away. If our transport can boost at 1G acceleration (adding roughly 10m^2 velocity every second) and can make it to .99c, the onboard trip will take a bit over five years for those on the ship. But here's where things get fun. Relativity means that those 5.14 years on the ship happened while 13.7 years passed outside the ship. If you take the same ship from Earth to Kepler-186f, it gets much worse. You have 12 years onboard to practice saying "Hello, my name is" in Keplerian, but 501 years have passed in the non-relativistic universe, and the language has changed beyond recognition.
In this case, I think you would develop a caste of spacers who live their entire lives on their ships and pass through the centuries as ghosts, visiting colonized worlds for trade and passing information. British author Alastair Reynolds has written an entire series, called Revelation Space, around this idea.
Science fiction loves to break the rules. Faster than light travel, magic energy sources that can provide endless power with no input, and fantastic but plausible technologies. Larry Niven also played with the concept with his Léshy Circuit stories, where vast slower than light starships used magnetic scoops to feed their fusion drives with interstellar hydrogen. Sometimes, the story is more interesting with you don't break physics. I should try that.
All travel times were generated at the Relativistic Star Ship Calculator http://convertalot.com/relativistic_star_ship_calculator.html
no subject
Date: 20 Apr 2019 23:02 (UTC)no subject
Date: 20 Apr 2019 23:14 (UTC)https://www.penguinrandomhouse.com/books/548431/alliance-rising-by-cj-cherryh-and-jane-s-fancher/9780756412715/
Earth to its closest station takes 10 years but farther out they have an FTL system that cannot be extended to Earth which leads to interesting interactions.
no subject
Date: 21 Apr 2019 03:09 (UTC)no subject
Date: 21 Apr 2019 04:55 (UTC)no subject
Date: 21 Apr 2019 10:04 (UTC)Still, I've got ideas for a colony on one. Gonna do a lot of handwaving and have local life up to the plants and maybe insects on land, all other life in the oceans stage.
Gotta do some research to find out more about earth in that period.
no subject
Date: 22 Apr 2019 05:06 (UTC)Good for you. But remember that it doesn’t have to be a brown dwarf! I read an article years ago that expressed peeve, that no one seemed to ever think of this. Take Earth. Roll a billion-sided die: How likely is it that the result will be anywhere near today?
Your exploration ship might look down on a world where green hasn’t happened yet! In such a case, or in any really unless you don’t mind it, preventing ecological contamination would be a constant headache.
[I like the idea I had for a game of Traveller, tho’ it could be used anywhere: A recovering Snowball. According to the models, once vulcanism and methane succeed in warming the place up to expose open ocean at the equator, when the tipping point is reached it could take as few as a thousand years to return to normal. On this world that process is underway.
Here, Mark Twain’s advice, “Buy land, they’re not making it any more,” is wrong! Continents are re-emerging from the glaciers year by year, more land all the time! Today’s realm of Ozymandias is tomorrow’s sandlot!
Then they started finding artifacts. To compress the backstory to diamond, this ancient planet-wide disaster which rendered extinct 99.9% of all life, was deliberate, an act of war. D’ ye suppose that weapon or how to make it, is still here…? Oh, purely scientific curiosity, of course!]
no subject
Date: 22 Apr 2019 08:24 (UTC)Then it takes a while to cool down because the CO2 has to get absorbed by the oceans and exposed rock. and gobbled up by the surge of returning plant life (mostly algae at first).
I did a post on the TML (Traveller Mailing List) years back about this. My idea was a colony that is in trouble because their "ice world" has tipped and is going by an unbearable hothouse in generation or less.
I've also got an old post here about a D&D world that's reaching the end of an ice age. As the glaciers retreat, the morraines have all sorts of interesting things getting exposed. Mangled chunks of precious metals, gems, and sometimes things that are way too *intact*.
The smart prospectors treat the intact stuff with *extreme* care. The dumb ones just pick them up and suffer the consequences.
And then there are the various dungeons, catacombs, undercities, etc exposed as the ice retreats.
scraped down to bedrock or farther. If you dig the rubble out of that staircase, what level of the dungeon will you be entering? And what may still be lurking there?
Undead will be inconvenienced by being sealed up for millenia. Other, weirder things (slimes, jellies etc
) will only be minorly impacted. And what fprgotten horrors may be there?
and that opening you found. Was it dug out by prospectors who got there first? Or did something dig its way *out*?
Lots of fun.
no subject
Date: 22 Apr 2019 09:25 (UTC)That D&D one does sound fun. You could even ramp up Lovecraft’s “Cool Air” and have the Eternal Tyranny of the Frost King needing bags of ice from Safeway PDQ…
“Neener neener!” the oppressed peon “meat popsicles” yell as a new age dawns and the snows melt.
'Who'l Ride'
Date: 22 Apr 2019 05:31 (UTC)But you might have to be generous in your definition of “habitable.” If you say merely, “Life can exist there and does,” that’s fine. But if you’re looking for Iowa [“Is this Heaven?” “No - it’s Iowa!” - Field of Dreams] then what with the ion flux causing violent continent-spanning lightning storms (kracka-BOOM-pzzz…) and the tidal stresses producing active volcanos (cough, cough) and near-constant, queasy earth tremors, the land never quite still, never knowing when your property will become “Fumarole Acres,” oh and the frequent, ferocious meteor impacts [“Incoming!” f=ma-ayyy, that gravity well is a doozy!]… Well, y’ know, Florida swampland was advertised as Paradise too…
ALL LOT SALES FINAL
HAVE A NICE DAY
Re: 'Who'l Ride'
Date: 22 Apr 2019 11:24 (UTC)Re: 'Who'l Ride'
Date: 22 Apr 2019 12:25 (UTC)Literally, of course that’s true. Thus Drake’s famous book, Habitable Planets For Man - making that distinction.
“Habitable” in common parlance assumes by us, i e an environment that will support us. In metal-crushing pressure and subfreezing temperatures, few would consider those ocean-floor volcanic vents “habitable,” yet indeed life exists there. (To our considerable astonishment at the time, you may recall.) Further, OP’s point was just that, regarding potential human habitation.
[I saw a science documentary on, “What if the Sun disappeared?” All the planets would go flying off, Earth would become a snowball indeed… Except there. Huddled about the superheated vents that warm and feed them, unaware of any such thing as Sun, they would perceive no change in their little worlds. If there is life on Europa, it may well be this.]
Updated to add: I wonder how those little shrimps and lichens and such got there. How did they survive to reach there?
no subject
Date: 22 Apr 2019 04:36 (UTC)One problem L Niven mentioned with his setup is that dealing with a near-lightspeed fuel flow is a daunting problem itself. If you have to slow it down, it slows you down.
When I met him at Magnum Opus Con, I very politely suggested that stored antimatter might be sprayed at the stream instead, with the further advantage that hydrogen per se is not required; any matter will do. He liked that idea.