Plausibility: apparently impossible

December 22, 2009 8:31 AM

Ten Ways to Travel in Deep Space from New Scientist.

Favorite Quote:

"Unfortunately, the Alcubierre drive has a host of problems. For one thing, the amount of energy needed to sustain the warp is greater than the total energy of the universe, although modifications to the shape of the bubble might help. The drive would also kick up a lot of radiation, which would threaten the astronauts' lives. And there is no evidence that exotic matter even exists."

posted by blue_beetle (48 comments total)

Additional Reading: Dark Rockets and Black Hole Starships
posted by blue_beetle at 8:34 AM on December 22, 2009 [1 favorite]

Perhaps crucially, calculations published in 2002 showed that it would be impossible for the ship to send signals to the front of the bubble, meaning that crew members could not control, steer or stop the ship.

RUNAWAY SHIP! Coming this fall on FOX.
posted by The Whelk at 8:37 AM on December 22, 2009

Just in time for (American) Christmas!
posted by DU at 8:39 AM on December 22, 2009

Aaaaand, once again, science reminds me that as far as our current understanding of the universe goes, we will effectively never leave our own neighborhood.

I note that they omitted one "real" option in favor of touching on a few silly ones, however - The generation ship. It doesn't need to go fast, it just needs to keep its occupants alive for hundreds or thousands of years. And we more-or-less have the tech to do it now (though it would cost trillions) - Pick a small asteroid in a convenient orbit, hollow it out and build a city inside, and then fling it off in a chosen direcion using basically what TFA describes as "nuclear pulse propulsion".
posted by pla at 8:58 AM on December 22, 2009 [2 favorites]

I like the idea of uploading my consciousness into a mutating von neuman machine that travels at a snails pace through the universe periodically making somewhat eccentric clones of my/itself and sending them off to their almost certain but maybe not destruction all the while keeping my conciousness occupied by playing thousands of parallel iterations of something like a simulation of reality and something like complex data processing and something like world of warcraft. Waxing and waning in and out of consciousness as the availaility of usable radiant energy fluxuates. Also it is shaped like a cool flying octopus with various tools for hands.
posted by I Foody at 9:08 AM on December 22, 2009 [9 favorites]

RUNAWAY SHIP! Coming this fall on FOX.

Actually, it's called Stargate Universe and it's on SyFy.
posted by lordrunningclam at 9:14 AM on December 22, 2009 [2 favorites]

So, you're saying the ship is slow, expensive, uses infinite energy, is physically impossible to build, can't be steered or communicated with, and kills its crew instantly?

I'll take five!
posted by blue_beetle at 9:17 AM on December 22, 2009

You could always try to get Ralph really pissed off...
posted by Zack_Replica at 9:18 AM on December 22, 2009 [1 favorite]

Why would you go to all the trouble of sending people, when you could send satellites out which broadcast back enough data for 'astronauts' to experience the trip in some kind of virtual reality.

Sure, it's not real-time, but so what.
posted by device55 at 9:50 AM on December 22, 2009

I note that they omitted one "real" option in favor of touching on a few silly ones, however - The generation ship.

One of my favorite short sci-fi stories involved the first large generation ship built, bound for some distant star. The story focused on their single minded dedication to reach their goal (which would help humanity somehow) at all costs. But due to technology advancement the stars were colonized during the hundreds of years of transport time. The ship and the remaining crew, dedicated for scientific space exploration of uninhabited deep space, arrived to a busy spaceport holding a welcome celebration in their honor for the equivalent of the local newscast.
posted by anti social order at 9:57 AM on December 22, 2009 [7 favorites]

I Foody: "I like the idea of uploading my consciousness into a mutating von neuman machine that travels at a snails pace through the universe periodically making somewhat eccentric clones of my/itself and sending them off to their almost certain but maybe not destruction all the while keeping my conciousness occupied by playing thousands of parallel iterations of something like a simulation of reality and something like complex data processing and something like world of warcraft. Waxing and waning in and out of consciousness as the availaility of usable radiant energy fluxuates. Also it is shaped like a cool flying octopus with various tools for hands."

Reading Tipler and watching the Matrix again, eh?

Has there been a story with aliens that build teleporters, seed that info (like Contact) in communications, get a society to build a mind upload copy device and transmit a brain copy to another world?
posted by symbioid at 10:06 AM on December 22, 2009

I note that they omitted one "real" option

That is not a drive type.
posted by Artw at 10:26 AM on December 22, 2009

It's not really explained in the game, but what about the "Mass Effect." To me it sounds like there's a way to eliminate an object's mass within spacetime, rendering it capable of FTL since there is no infinite energy barrier to acceleration beyond C if there is no mass. I realize "eliminate an object's mass" is basically nonsense.
posted by autodidact at 10:38 AM on December 22, 2009

The ship and the remaining crew, dedicated for scientific space exploration of uninhabited deep space, arrived to a busy spaceport holding a welcome celebration in their honor for the equivalent of the local newscast.

Man, I'd be pissed. We'd have developed a whole new culture by then, and a whole different language. Judging by current potential, our morphology would even have changed substantially. Would we recognize each other, or be able to communicate? Why the hell didn't they just pick us up?

"What? We made a new species of Human for nothing?"
posted by cmoj at 10:44 AM on December 22, 2009

I realize "eliminate an object's mass" is basically nonsense.

It depends if gravitational and inertial mass are the same thing. Still an open question.
posted by GuyZero at 10:45 AM on December 22, 2009

The Whelk: RUNAWAY SHIP! Coming this fall on FOX.

Don't give them another excuse for a reality series.
posted by Drasher at 10:51 AM on December 22, 2009

I was hoping for cool pictures. Disappointed.
posted by sourwookie at 10:59 AM on December 22, 2009

?The generation ship. It doesn't need to go fast, it just needs to keep its occupants alive for hundreds or thousands of years

And entertained. Mefi's own cstross already made this point. You can't afford to have everyone doing useful work all the time, because if something happens that kills, say, 30% of the crew, the mission would fail for lack of crew. So, you need to carry extra crewmen, because there are no reliefs, and replacements are hard (Basically, you give birth to them, wait for them to be old enough to train, and train them. If you're seriously shorthanded, when do you get time to train them properly?)

So, those spare crewman need to be kept sane.

Personally, I don't think generation ships work at all -- too many ways for a small society to conflict, and the worst part is there is nowhere for the losers of the conflict to go. It becomes fascinating when crew section A hates crew section B, there's nowhere for them to go, and if you kill off one section, the other section dies because (say) all the guys who knew how the drive worked were in the other section, or the like.

Heck, we're talking thousands of years. Name a human civilization that's gone that long without conflict. Heck, what happens when a very charismatic crewman stares at something too long and thinks Ghod is talking to him...
posted by eriko at 11:05 AM on December 22, 2009

^ Sadly you'd probably need a strictly authoritarian structure on a generation ship. Not so much like a flying community as a flying lord and his vassals.
posted by autodidact at 11:09 AM on December 22, 2009

The generation ship thread.
posted by Artw at 11:13 AM on December 22, 2009

anti social order: I believe the story you're thinking of is "The Shoulders of Giants", by Robert J. Sawyer.
posted by ubernostrum at 11:15 AM on December 22, 2009 [2 favorites]

Er, Robert K. Sawyer, sorry. And, yeah, that's the story.
posted by ubernostrum at 11:16 AM on December 22, 2009

Or not; some places seem to give him a 'K', some a 'J'. I give up.
posted by ubernostrum at 11:17 AM on December 22, 2009 [1 favorite]

So this displays my total lack of understanding of (astro)physics, but how do we know that the laws of physics are consistent across all parts of the universe rather than a byproduct of our ability to perceive them? I'm thinking something like the "zone of thought" in Vinge's A Fire Upon the Deep.

Clearly, no scientists think that the laws of physics change drastically elsewhere in the universe, but I've never understood exactly why that's impossible. Plus I really want a FTL spaceship. And a pony.
posted by digitalprimate at 11:18 AM on December 22, 2009

the other section dies because (say) all the guys who knew how the drive worked were in the other section, or the like.

As one of the sci-fi authors I've read suggests, spaceships will eventually become too complex for people to really understand - you'd need computers/robots to handle nearly all tasks.
posted by exhilaration at 11:19 AM on December 22, 2009

You can't afford to have everyone doing useful work all the time, because if something happens that kills, say, 30% of the crew, the mission would fail for lack of crew.

Everyone works for 6-8 hours/day, but in 3-4 offset shifts. If 30% die, you just increase the workload to 9-12 hours/day for a few years.
posted by DU at 11:30 AM on December 22, 2009

if you kill off one section, the other section dies because (say) all the guys who knew how the drive worked were in the other section, or the like.

The entire ship would need to be designed like the Long Now Clock. Operation is clear via inspection where "inspection" might mean "years of dedicated study". As long as you have raw materials (either actually raw or recycleable) you can make all the tools and instruments you might need to rediscover the lost principles.
posted by DU at 11:32 AM on December 22, 2009

Aaaaand, once again, science reminds me that as far as our current understanding of the universe goes, we will effectively never leave our own neighborhood.

We've already done plenty of crazy shit we used to think was impossible. Anything can happen a century or two from now.
posted by Lobster Garden at 12:20 PM on December 22, 2009 [1 favorite]

So this displays my total lack of understanding of (astro)physics, but how do we know that the laws of physics are consistent across all parts of the universe rather than a byproduct of our ability to perceive them?

We don't.
posted by Blazecock Pileon at 12:33 PM on December 22, 2009

Thinking is the best way to travel.
posted by Kirth Gerson at 12:40 PM on December 22, 2009 [1 favorite]

Why would you go to all the trouble of sending people, when you could send satellites out which broadcast back enough data for 'astronauts' to experience the trip in some kind of virtual reality. Sure, it's not real-time, but so what.

The earth isn't going to last forever and, for reasons that honestly escape me, some people think that we should strive to carry on the human race forever.
posted by coolguymichael at 1:00 PM on December 22, 2009

The earth isn't going to last forever and, for reasons that honestly escape me, some people think that we should strive to carry on the human race forever.

Carl Sagan:

"In our tenure on this planet, we've accumulated dangerous evolutionary baggage: propensities for aggression and ritual, submission to leaders, hostility to outsiders... We've also acquired compassion for others, love for our children, a desire to learn from history and experience, and a great soaring passionate intelligence."

"Our obligation to survive and flourish is owed not just to ourselves, but also to that cosmos, ancient and vast, from which we spring."
posted by Lobster Garden at 1:14 PM on December 22, 2009 [5 favorites]

"Our obligation to survive and flourish is owed not just to ourselves, but also to that cosmos, ancient and vast, from which we spring."

Sagan is right. Because what if we're it? It's quite possible we are the only intelligent life in the universe. What if we are the only means for the universe to know it self? I vote we keep the old girl going.
posted by tkchrist at 2:30 PM on December 22, 2009

Some dedicated scientists I know who happen to be eight-year-old girls are working on a FTL drive that involves using small fairies housed in metal cylinders to produce amounts of a substance referred to by them as "sparkles" to generate propulsive force. The sparkles appear to be generated through some biological process by the fairies, who subsist on the scent of lilac produced by a large greenhouse held in the middle of the ship. The fairies have a working life of roughly two weeks apiece before ennui sets in and must be rotated with replacement teams from the greenhouse. The exhaust sparkles can later be harvested by other ships and used for craft projects.

I will be reporting further on their theoretical work once I can make better sense of their blueprints, which are actually blue, being scrawled in crayon on construction paper.

Makes about as much sense as exotic matter.
posted by JHarris at 3:43 PM on December 22, 2009 [3 favorites]

Has there been a story with aliens that build teleporters, seed that info (like Contact) in communications, get a society to build a mind upload copy device and transmit a brain copy to another world?

"The Hydrogen Wall" by Gregory Benford, if I remember correctly. Also, Robert J. Sawyer's novel Rollback has the aliens broadcasting their genome and the technology to clone them from scratch, but not any particular individuals' brain states.
posted by teraflop at 4:33 PM on December 22, 2009

anti social order: I believe the story you're thinking of is "The Shoulders of Giants", by Robert J. Sawyer.
posted by ubernostrum at 11:15 AM on December 22 [1 favorite +] [!]

Actually A.E. van Vogt wrote essentially the same story in 1948: Far Centaurus. Sawyer wrote his in 2000. So van Vogt beat him by about 52 years.
posted by George_Spiggott at 4:40 PM on December 22, 2009

Sorry, make that 1944, when it appeared in "Astounding". It was first collected in 1948.
posted by George_Spiggott at 4:42 PM on December 22, 2009

I note that they omitted one "real" option in favor of touching on a few silly ones, however - The generation ship. It doesn't need to go fast, it just needs to keep its occupants alive for hundreds or thousands of years. And we more-or-less have the tech to do it now (though it would cost trillions) - Pick a small asteroid in a convenient orbit, hollow it out and build a city inside, and then fling it off in a chosen direcion using basically what TFA describes as "nuclear pulse propulsion".

As noted in the last thread on this. The generation ship is not a real or practical idea. We do not possess any kind of technical capability to capture, hollow out an asteroid, and equip it with supplies and propulsion necessary for interstellar journeys. The engineering, social/political, and logistical challenges are not even close to current capabilities. You are belling the cat here.
posted by humanfont at 6:33 PM on December 22, 2009

The engineering, social/political, and logistical challenges are not even close to current capabilities.

Yeah, but I grok the engineering challenges -- and a fundamental rule of engineering is if it is possible, it *will* happen. What wipes out the generation ship is not just the social and logistical challenges, but engineering.

If we can build a .01c starship, it won't be long before we can build a .9c ship, and not long after that, a .99c starship -- which we could then send the designer of the .1c starship on, who would be there, *alive*, when the .1c starship arrives.

Indeed, generation ships are a dumb idea, when you remember Relativity. Want to get a crew to the other side of the galaxy? Easy, give me 1g acceleration.

Here's how weird relativity is. If I have a constant acceleration of 1 gravity, then it will take me to the stars -- and far beyond. 10 light years will take 11.7 years, here, but only 4.5 years, ship time. And it gets even better. A thousand light years -- a hundred times father? 13 years, ship time. For 10,000 light years, same acceleration? It's 17 years, ship time (and for 30K, center of the galaxy? 20 years.) A *million* light years? 26.8 years. Two million? (we're now talking the Andromeda Galaxy) -- 28.1 years, ship time.

Fifteen *billion* light years? 45 years, ship time. Of course, the Earth is dead 15 times over, but you could ship out at 30 and be at the edge of the universe before you die. Get that acceleration up, and it's easy -- if you're on the ship. At 10g constant acceleration, you can travel to the center of the galaxy in 2.45 years, ship time -- and to the edge of the universe that we can see now -- some 15Gly away -- in 5.

It's all about the nines. The universe, to the ship traveller, is forbiddingly large at .1c, only fucking huge at .9c, and tiny at .9999999999999c. Alastair Reynolds nailed this -- it'll be the lighthuggers who travel the stars, not generation ships. Lord knows the engineering challenges are *staggering* -- but they're at least theoretically possible.

Which means we will do it, if humanity doesn't kill itself off in the meantime. Alas, I'm deeply afraid the answer to the Fermi Paradox is "they killed themselves off before they could reach the stars."
posted by eriko at 7:18 PM on December 22, 2009 [4 favorites]

Showing my ignorance, but

10 light years will take 11.7 years, here, but only 4.5 years, ship time

So do you need to provide energy to accelerate and decelerate the ship for the 24 years the ship appears to be running to an outside observer, or the 9 years it seems to be running to those on board? Either way, a lot of juice, but one seems to be three times the other.
posted by maxwelton at 8:34 PM on December 22, 2009

So do you need to provide energy to accelerate and decelerate the ship for the 24 years the ship appears to be running to an outside observer, or the 9 years it seems to be running to those on board? Either way, a lot of juice, but one seems to be three times the other.

To those on the ship, they've needed to keep up a 1G acceleration for 9 years. In the outside observer's frame of reference, they've been accelerating for 24 years, but at much less than 1G for nearly all that time.

A lot of juice. Effectively that's 2.75+ billion m/s delta-V. Back of the napkin math says you need 99.995% of your rocket to be fuel, assuming of course that you're using pure matter-antimatter collisions; every other option gets much worse. That kind of speed is *not* happening with a rocket. Even with a laser-pushed light sail it's tricky. Relativity says that, although that "constant" 1G acceleration looks constant in the ship's frame of reference and looks like it's decreasing to the folks back home, the energy required to maintain it just keeps increasing and increasing. The light reflecting off the sail actually red-shifts and doesn't impart as much momentum during the middle of the trip as it did at the start.

The article actually left out the least implausible option I've seen for a manned interstellar drive: Nuclear Salt Water Rockets You still need 90% of your rocket to be (enriched fissionable) fuel, and it still won't get you to another star for a few centuries, so the remaining 10% had better include one hell of a generation ship. But it is cool that interstellar flight is now conceivable (albeit still grossly impractical/uneconomical) technology, not just "magic".
posted by roystgnr at 10:06 PM on December 22, 2009

Want to get a crew to the other side of the galaxy? Easy, give me 1g acceleration.

You just put a different bell on the same animal. The solutions all suffer from the same problem, they are all well beyond our current capabilities. Time dilation also screws you because if you go fifteen billion light years what the heck does the universe even look like at that point? We would have to project what things look like 30 billion years in the future since we are observing things 15 billion years in the past when we send you out.
Even assuming some breakthrough where the engineering problem of 1g travel goes away. Suppose we find some planet worth going just 20 or 30 light years away. We peer through the telescope and see the 02 line on his nearby planet and then what? Listen for radio, send a few directed messages, wait for a reply? Or do we just leap in our rocket ship and crash their party, hoping we don't bring some pathogen with us that obliterates them, or get exposed to something that kills us all. The space seed thing looks great unless you have to destroy some other biological system to replicate humanity. Also based on the ethics of reciprocal conduct we would assume that another species could do the same to us. I suppose you might find some early stage planet with no life and just waiting for us to show up and terraform, but we're pretty far from being able to terraform anything at this point.
posted by humanfont at 12:56 AM on December 23, 2009

Easy, give me 1g acceleration.

If we're asking Santa for solutions, why not just ask for teleportation in the first place?
posted by DU at 6:41 AM on December 23, 2009 [3 favorites]

Some dedicated scientists I know who happen to be eight-year-old girls are working on a FTL drive that involves using small fairies housed in metal cylinders to produce amounts of a substance referred to by them as "sparkles" to generate propulsive force.

JHarris you'll be receiving a cease and desist order from my niece's law firm shortly. Madeline Fairy Propulsion LLC has secured multiple patents on core technologies including fairy containment, Lifelac(c) scent meals, and Sparkle Motion(c) (legally licensed from the world renowned dance troupe).
posted by Babblesort at 9:04 AM on December 23, 2009 [2 favorites]

Not a bad article- it even provides a work-around to the basic problem ramscoops have of being better brakes than propulsion systems.

Pity it appeared in New Scientist; I'd like to see the topic treated by a science website some time.
posted by happyroach at 12:47 PM on December 23, 2009 [1 favorite]

Interstellar distances only seem so vast because our lives burn out so quickly. Imagine a form of life with a much slower metabolic process - ie, something that thought at a much slower "clock speed". For such creatures, a thousand-year trip to another star wouldn't be a big deal. I've often wondered if such life is out there, and if we'll ever be able to perceive or communicate with it. Imagine communicating with a creature that took so long to understand you and respond, only your children would know the answer to a question you asked it.

If there is other life in the universe, I'd be willing to bet a large part of it is like that.
posted by heathkit at 4:45 PM on December 23, 2009 [2 favorites]

heathkit:Interstellar distances only seem so vast because our lives burn out so quickly. Imagine a form of life with a much slower metabolic process - ie, something that thought at a much slower "clock speed". For such creatures, a thousand-year trip to another star wouldn't be a big deal.

[...]

Time, it seems, doesn't flow...
For some it's fast, for others slow.
In what to one race is no time at all
Another race may rise and fall.

The virus spread like burning fire...
The sea of dread rose higher and higher.
The crystal ones had to fight
By causing suns to ignite.
...self defense. It is their right.

Back when all the stars were young,
Before the Minstrel songs were sung,
When this galaxy was new
There came from far the crystal few.
Gradually they spread through space.
They were the first...the only race.

And harder still to recognize
That which lies before one's eyes.
So many races have believed
In only what was preconceived.
That which is ancient may be new...
It all depends on point of view.

[...]

-Excerpt from "The Minstral Song," in Starflight, by Binary Systems.
posted by JHarris at 2:10 AM on December 24, 2009

Endurium is exactly what I was thinking about JHarris, thank you
posted by heathkit at 10:09 PM on December 26, 2009