dystopic dystopic

bussard ramjets, cryonic stasis, and exoplanetary colonization

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bussard ramjets, cryonic stasis, and exoplanetary colonization

what will it take?

from GalCiv2 Forums
hello everyone,

i'm a bit of a writer, and i can't help but feel drawn to science fiction. that shouldn't be surprising.

lately i've been reading up a great deal on theoretical physics, exobiological speculation, and all that. i was dismayed at first to learn that the chances of faster-than-light travel being physically possible are slim. it was also pretty discouraging when i sat down and looked at the actual speeds that'd be required to traverse sizable parts of the galaxy in a single conscious lifetime. it was a kick when i was down to learn about how difficult terraforming probably would be. but the more i've been learning, the more i've been excited about telling a different kind of science fiction story.

to draw an analogue to our world, the thing that made both the european colonial age and the modern process of globalization have been technology. it's not that we couldn't go to various places around the world before, it just cost too damn much to make anything worth it. i got my BA in sociology, and these sorts of things interest me.

if FTL travel isn't possible, then more than likely it'll be too damn costly to ever colonize beyond our own solar system as the way it's been envisioned in most of the celebrated scifi universes. But there are examples such as Arthur C. Clarke's Songs of a Distant Earth or Sid Meier's Alpha Centauri where humans colonize to escape destruction on earth.

recently i had the chance to meet both Kim Stanley Robinson and Geoff Ryman. Robinson is a hard scifi writer after my own heart; the Mars Trilogy is a really interesting look at our first attempts to colonize within our own star system. Ryman was actually more interesting to talk to, though. maybe because few people have ever heard of him (i was only there because i work at UCSD where he was being hosted). but i actually got to talk to him. he said he thinks we probably won't ever leave our galactic neighborhood.

i'm interested in writing a hard scifi story (or series) myself. i'm interested from a sociological point of view: what would drive us to colonize space? from a writer's point of view, i want to keep the earth around, so i'm not interested in a flight from disaster. what would societies be like after colonies were established? trade would be difficult, but not impossible. same goes for war.

while i'm certainly interested in contributions along those lines, i'm also interested in learning more about the hard science and engineering behind interstellar travel. i've got a lot of questions i haven't been able to answer through wikipedia and google alone. but i'm not about to list them all here.

it seems like a discussion about real ("real") colonization and space travel could use a place on these boards.

i'll kick it off. i've been reading up on propultion especially, and bussard ramjets seem like the most economically feasible option since they gather their fuel as they go - perhaps especially if it could be hybridized with another form such as antimatter-catalyzed fusion. the wikipedia article on bussard ramjets describe that they'd probably need what is essentially a magnetic funnel or ramscoop to gather interstellar hydrogen as propellant.

The mass of the ion ram scoop must be minimized on an interstellar ramjet. The size of the scoop is large enough that the scoop cannot be solid. This is best accomplished by using an electromagnetic field, or alternatively using an electrostatic field to build the ion ram scoop. Such an ion scoop will use electromagnetic funnels, or electrostatic fields to collect ionized hydrogen gas from space for use as propellant by ramjet propulsion systems (since much of the hydrogen is not ionized, some versions of a scoop propose ionizing the hydrogen, perhaps with a laser, ahead of the ship.) An electric field can electrostatically attract the positive ions, and thus draw them inside a ramjet engine. The electromagnetic funnel would bend the ions into helical spirals around the magnetic field lines to scoop up the ions via the starship's motion through space. Ionized particles moving in spirals produce an energy loss, and hence drag; the scoop must be designed to both minimize the circular motion of the particles and simultaneously maximize the collection. Likewise, if the hydrogen is heated during collection, thermal radiation will represent an energy loss, and hence also drag; so an effective scoop must collect and compress the hydrogen without significant heating.


talk about kick-butt imagery! spirals of heated gas careening towards a ship only to be fused and expelled in a jet plume? sweet.

anyway, i've written enough, and i hope it hasn't put anyone off. some of the the community here has proven to be very well read with regard to these kinds of science, so i thought it'd make a great topic for discussion: all things related to space exploration and colonization with reasonable extrapolations of current technology.

my biggest point of curiostiy was with respect to ramjets, so i'll take the kickoff: could the spiral motion of the inbound gas somehow be harnessed to artficially generate gravity by rotating the ship, instead of producing drag?

any volunteers?

final words: i hope no one minds my double-motive. i won't try to steer any dicussion, though if things quiet down i might pose more general questions to keep it going; i encourage anyone interested to pose your own!
off-topic
437,030 views 930 replies
Reply #301 from GalCiv2 Forums Top
i'm ducking away from my responsibilities (twisted my ankle, so i'm thinking of it as worker's comp).

a few more thoughts on EM transmissions. first, just keep in mind that i'm partly playing devil's advocate here: besides being fun from time to time, it's also a good mental habit of a writer IMO. i agree with deny's original points for the most part.

we've been dumping EM signals into space for 70 years, yes, but how long is that in the grand scheme of the evolution of life and the age of the universe? not long. burst transmissions are more efficient for us because of the way we use them (capitalism) and the alternatives we had available when the technology was put to commercial use (the telegraph). sure, we have other uses besides making money, but if you cut that one out we don't make nearly so much noise.

and radio technology is already outdated. but think outside the immediate human box. we don't really need to use radio anymore. wired communication is now much more efficient for us; the problem we face now is developing infrastructure. most of our cutting-edge wireless technologies aren't going to go very far into space (with any appriciable strength).

finally there's also developing radio technology in the first place. while its abundance in the universe suggests a lot to anyone with intelligence, we only learned to generate radio waves after we'd learned to harness electricity. alien life that lived under water, for example, would have a much more difficult time developing electricity, and they might have to learn to convert some other form of energy to radio waves (perhaps sound vibrations or heat) - who knows what kind of challenge that'd present.
Reply #302 from GalCiv2 Forums Top
another question how long has been since we have been sending out signals strong enough to make it to another star system. and with a general broadcast would any signal be strong enough.
Sins of a Solar Empire II
Reply #303 from GalCiv2 Forums Top
Aliens will never make contact otherwise they would have to pay for all the free movies and music their getting from us now!
Reply #304 from GalCiv2 Forums Top
another question how long has been since we have been sending out signals strong enough to make it to another star system. and with a general broadcast would any signal be strong enough.


it's hard to answer this question without making some speculations about receiving antennas and computer programs to analyze radio noise (even if they receive the signal, they still have to be able to separate it from background noise). the signal itself is made of photons, and they never disappear; what really happens is that they become too diffuse to be distinguishable from other EM sources.

so, that's the principal, but once again i can't really fill in any numbers.

Aliens will never make contact otherwise they would have to pay for all the free movies and music their getting from us now!


LOL! not if they've got broadband.
Reply #305 from GalCiv2 Forums Top
if i am not mistaken, gravity is "faster" than light. if string ("M") theory turns out to be correct, it is also the only force that can be used to probe other dimensions. while i don't anticipate intelligent life to be communicating with gravitational waves, much less so in a "hard science" setting, it would allow to circumvent the speed of light. that being said, i think communication in the EM spectrum would be the first choice for a fleet or perhaps within a solar system.
Reply #306 from GalCiv2 Forums Top
Aliens will never make contact otherwise they would have to pay for all the free movies and music their getting from us now!


somebody, I don't know who, said this:

"the best sign for extraterrestrial intelligence that we have is that they haven't tried to contact us."
Reply #307 from GalCiv2 Forums Top
it's hard to answer this question without making some speculations about receiving antennas and computer programs to analyze radio noise (even if they receive the signal, they still have to be able to separate it from background noise). the signal itself is made of photons, and they never disappear; what really happens is that they become too diffuse to be distinguishable from other EM sources.

so, that's the principal, but once again i can't really fill in any numbers.



this answers why we have not recieved any signals with i love lucy from space.
Reply #308 from GalCiv2 Forums Top
LOL! not if they've got broadband.


hehehe, well they might have a strict moral code not to steal anything who knows?

"the best sign for extraterrestrial intelligence that we have is that they haven't tried to contact us."


well i guess that prooves alien intelligence exists, since if there are no aliens, they would not be able to contact us thus prooving their intelligence!!
Reply #309 from GalCiv2 Forums Top
and radio technology is already outdated. but think outside the immediate human box. we don't really need to use radio anymore. wired communication is now much more efficient for us; the problem we face now is developing infrastructure. most of our cutting-edge wireless technologies aren't going to go very far into space (with any appriciable strength).


I work as a network crisis manager for the government, and I can tell you with certainty that, except for a VERY few 'must survive' C&C networks connecting a very limited number of nodes, there is NO SUCH THING in the world today as truly 'wired' communication beyond a local urban area. EVERYTHING that you think is a land line goes over a microwave or sat shot at some point in the path. Europe a little less so, most of the rest of the world even more than North America.

And the use of the broadcast EM spectrum worldwide has constantly INCREASED, it has never diminished. Example: When I was growing up, 40-(ahem) years ago, even in an urban area you had to actually TURN the radio knob in your car to find the selection of 20 or so stations in range (AM). Now, I have an AM range and 2 FM ranges so full of stations that I have to use a scanner with finer discrimination than my fingers to dial in on them; I must have access to over 100 stations in the Balt-Wash region.
Another example: Even during WWII, smaller warships and merchantmen had 1 radio. Now a warship has as many as 50 emitters, including several low frequency, and the least well equipped commercial vessel has at least 3 radio devices. Aircraft all have at least 2 'radios'.

Yes, many wavelengths will stay within the ionosphere, but there is some leakage of all of it, and there IS more of ALL of it than ever before. Note that to even make any use of communications sattelites, we must send them densely multiplexed signals BEYOND the electronically shielding layers of the atmosphere.

So, whether ET is phoning home or not, we are certainly phoning him.
drrider
Reply #310 from GalCiv2 Forums Top
and radio technology is already outdated. but think outside the immediate human box. we don't really need to use radio anymore. wired communication is now much more efficient for us; the problem we face now is developing infrastructure. most of our cutting-edge wireless technologies aren't going to go very far into space (with any appriciable strength).


I work as a network crisis manager for the government, and I can tell you with certainty that, except for a VERY few 'must survive' C&C networks connecting a very limited number of nodes, there is NO SUCH THING in the world today as truly 'wired' communication beyond a local urban area. EVERYTHING that you think is a land line goes over a microwave or sat shot at some point in the path. Europe a little less so, most of the rest of the world even more than North America.

And the use of the broadcast EM spectrum worldwide has constantly INCREASED, it has never diminished. Example: When I was growing up, 40-(ahem) years ago, even in an urban area you had to actually TURN the radio knob in your car to find the selection of 20 or so stations in range (AM). Now, I have an AM range and 2 FM ranges so full of stations that I have to use a scanner with finer discrimination than my fingers to dial in on them; I must have access to over 100 stations in the Balt-Wash region.
Another example: Even during WWII, smaller warships and merchantmen had 1 radio. Now a warship has as many as 50 emitters, including several low frequency and direct surface to satellite capability, and the least well equipped commercial vessel has at least 3 long-haul radio devices. Aircraft all have at least 2 'radios'.

Yes, many wavelengths will stay within the ionosphere, but there is some leakage of all of it, and there IS more of ALL of it than ever before. Note that to even make any use of communications satellites, we must send them densely multiplexed signals BEYOND the electronically shielding layers of the atmosphere.

So, whether ET is phoning home or not, we are certainly phoning him.
drrider
Reply #311 from GalCiv2 Forums Top


well i guess that prooves alien intelligence exists, since if there are no aliens, they would not be able to contact us thus prooving their intelligence!!


that REALLY wasn't the point.
Reply #312 from GalCiv2 Forums Top
So, whether ET is phoning home or not, we are certainly phoning him.
drrider


If there are Aliens who are aware of us, then they must have a very tight hold on their society, to the point that they have no dissenting, foolish, clumbsy or insane individuals who would contact us. Imagine trying to have such controll over the entire population of Earth?! The nature of our species would make that impossible, so with that in mind i do wonder about the nature of an alien species that could contain their entire population not to contact Earth?
Reply #313 from GalCiv2 Forums Top
your assuming that their general population knows
Reply #314 from GalCiv2 Forums Top
If there are Aliens who are aware of us, then they must have a very tight hold on their society, to the point that they have no dissenting, foolish, clumbsy or insane individuals who would contact us. Imagine trying to have such controll over the entire population of Earth?! The nature of our species would make that impossible, so with that in mind i do wonder about the nature of an alien species that could contain their entire population not to contact Earth?


70-80 years of large scale radio output.
70-80 lightyears is not a very big volume. ("Space is Big, really quite extremely Huge.") Give it another 2-3000 years and see who calls back.

drrider
Reply #315 from GalCiv2 Forums Top
Oh, and read "Contact", for Carl Sagan's fictional treatment of the whole subbject. Pretty fun read, especially since he did know a little about the astrophysics and all.

drrider
Reply #316 from GalCiv2 Forums Top
I work as a network crisis manager for the government, and I can tell you with certainty that, except for a VERY few 'must survive' C&C networks connecting a very limited number of nodes, there is NO SUCH THING in the world today as truly 'wired' communication beyond a local urban area.


i guess i should have prefaced what i was saying a little better. i'm imagining ships and structures built from the ground up with the latest technology and no large empty spaces separating facilities and population centers. but your point is well taken nonetheless.

if i am not mistaken, gravity is "faster" than light. if string ("M") theory turns out to be correct


does M theory state that gravity is faster than light? relativity predicts they both travel at c, but that gravity isn't slowed by moving through dense matter like air.

Give it another 2-3000 years and see who calls back.


another excellent point. 80 years isn't even a drop in the bucket on cosmological scales. maybe more like an H2O molecule in the ocean.

Oh, and read "Contact", for Carl Sagan's fictional treatment of the whole subbject. Pretty fun read, especially since he did know a little about the astrophysics and all.


great book. so-so movie (it was kinda slow).
Reply #317 from GalCiv2 Forums Top
your assuming that their general population knows


possibly, if they have very good signal jamming technology, and private citizens don't own spaceships.

does M theory state that gravity is faster than light? relativity predicts they both travel at c, but that gravity isn't slowed by moving through dense matter like air.


If the sun suddenly dissapeared, lets say because aliens teleported it to their galaxy, we would not know it for about 9 minutes! I just wonder if Earth would still continue orbiting the sun for 9 minutes as well? Gravity continuing for 9 minutes just the same as the light?

Reply #318 from GalCiv2 Forums Top
If the sun suddenly dissapeared, lets say because aliens teleported it to their galaxy, we would not know it for about 9 minutes! I just wonder if Earth would still continue orbiting the sun for 9 minutes as well? Gravity continuing for 9 minutes just the same as the light?


THIS is a GREAT question! Any of the academics out their have a glimmer of what answer current astrophysical thought would support??

drrider
Reply #319 from GalCiv2 Forums Top
If the sun suddenly dissapeared, lets say because aliens teleported it to their galaxy, we would not know it for about 9 minutes! I just wonder if Earth would still continue orbiting the sun for 9 minutes as well? Gravity continuing for 9 minutes just the same as the light?
THIS is a GREAT question! Any of the academics out their have a glimmer of what answer current astrophysical thought would support??


according to relativity, yes it would. of course, we wouldn't know it'd happened for those 8.3 minutes.

whether or not relativity is 100% accurate is one question. also, more specifically gravity doesn't propogate, but rather changes in the gravitational field. think about watching a wave move across a sheet when you're making a bed.

WWW Link
WWW Link
WWW Link

and of course, wikipedia to the rescue: WWW Link
Reply #320 from GalCiv2 Forums Top
So the time between cause and effect is always limited by distance correct?

Cause and effect and distance all exist only because time exists correct?

I am trying to reach some kind of obscure conclusion here, which is just beyond the grasp of my understanding?
Reply #321 from GalCiv2 Forums Top
If, according to an observer at rest relative to the sun, the two events happened at the same time, then an observer moving towards the sun from the Earth would say that the sun disappeared before the Earth felt the effects, and an observer moving in the opposite direction would say the reverse: that the Earth actually felt the effects before anything happened to the sun, which most folks would agree is ludicrous.


WWW Link
Reply #322 from GalCiv2 Forums Top
If, according to an observer at rest relative to the sun, the two events happened at the same time, then an observer moving towards the sun from the Earth would say that the sun disappeared before the Earth felt the effects, and an observer moving in the opposite direction would say the reverse: that the Earth actually felt the effects before anything happened to the sun, which most folks would agree is ludicrous.


Relativity does not change the reality of an event, it only changes the time when you feel the effect.
Reply #323 from GalCiv2 Forums Top
just beyond the grasp of my understanding?


well, Einstein didn't become synonymous with genius for no reason

So the time between cause and effect is always limited by distance correct?


the physical concept you're getting at is communication, IIRC, and yes, basically.

Cause and effect and distance all exist only because time exists correct?


distance (space) and time are dimensions in the 3+1 universe. space doesn't exist because time exists; they exist for the same reason. why they exist is another question. why only 3+1? if i'm remembering things correctly some speculation attributes it to quantum fluctuations during the first intervals of the big bang. but that all boils down to a deeper question: why existence at all? feel free to speculate on god and whatnot, just be respectful and cogent, if possible.

danielost, your quote is useful but the important part is: "If, according to an observer at rest relative to the sun, the two events happened at the same time..." according to relativity, two events that happen at the same time cannot be causally related unless they happen at the same place. the article goes on to say:

"...perhaps we can't detect instantaneous events, but surely they can sure occur, can't they? Sorry, but no, they can't. In the Einsteinian universe, instantaneity--that is, event X instantaneously causes effect Y at distance Z--is impossible in a meaningful sense, since for reasons we needn't delve into it would involve communication at faster-than-light speeds."

the article further goes on to say is that this phenomenon strongly suggests the existance of a gravitational medium--gravitons.

Relativity does not change the reality of an event, it only changes the time when you feel the effect.


yes, exactly. well, more exactly, your perception of the duration of the event (or duration between cause and effect, and duration of everything, and that's relative to your speed).
Reply #324 from GalCiv2 Forums Top
according to my belief god created time so that all things wouldn't happen at the same time.

and before you yell.

lets look at it a different way.

we live in a timed universe.

so does the turtle.

but do we observe time the same way no.

time observation is dependent on metabolism

a turtles metabolism is so slow that one hour to us would be a lot longer to the turtle. sorry that got away from me. but you should be able to see what i am saying.

Reply #325 from GalCiv2 Forums Top
here is another thing to ponder.


a black holes gravity is so strong that nothing can escape from it.

but in reality there is one thing that does escape.

in fact the bigger the black hole the more of it escapes.