dystopic dystopic

bussard ramjets, cryonic stasis, and exoplanetary colonization

bussard ramjets, cryonic stasis, and exoplanetary colonization

what will it take?

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!
436,377 views 930 replies
Reply #776 Top
except that astronomers have stated this year that light does not travel at the same speed in space.
Reply #777 Top
vacuum is simply emtiness... there's nothing there, no atoms, no nothing, if space isn't a vacuum, then please explain what is there.
Reply #778 Top
if space isn't a vacuum, then please explain what is there.
End of quote


Space isn't a "perfect" vacuum. In our solar system, all the gas has coalesced into the planets, their moons, or the Sun itself. However, beyond a certain distance (don't know exactly what the distance is), the pull of the Sun's gravity isn't strong enough to attract the gas, so there is in fact a cloud of gas known as the interstellar medium (which we have referred to frequently in this thread), which is theorized to pervade the universe in regions where there isn't a significant gravity well. Note that this cloud isn't like clouds or even the atmosphere on Earth, it is much thinner, but nonetheless it is present and therefore is technically not a total vacuum.

Reply #779 Top
but nonetheless it is present and therefore is technically not a total vacuum.
End of quote


in fact the space in side of the solar system is a better vacuum than the above.
Reply #780 Top
Space isn't a "perfect" vacuum.
End of quote


Assuming the galaxy is expanding out from a central point, then this would explain why you will not find a perfect vacumm within the sphere of that expansion. I think you would have to go out as far as the outer rim of the galaxy to find perfect vacuum.
Reply #781 Top
but the subtler point is that perfect vacuum does exist on a quantum level, between subatomic particles. when you integrate relativity to that level (quantum electro- and chromo- dynamcs), you can see that Einstein's equations weren't wrong - they describe things that absolutely do happen in the universe - they were just incomplete.

while the quest for a theory of everything is always a siren's call to physicists, a lot of modern applied physicists basically take on the view of using the 'most complete' theory for the problem at hand.

remember that c is the speed of light in a perfect vacuum. c is also the speed of gravity. why the speed of vacuous light and gravity are c, and why c is exactly what it is, i haven't ever found a fully satisfactory answer to. also, i think the actual speed that light travels in a massive medium is called, in physics, the propogation speed, IIRC.
Reply #782 Top
why the speed of vacuous light and gravity are c, and why c is exactly what it is, i haven't ever found a fully satisfactory answer to.
End of quote


That is a good question! any wild theories?
Reply #783 Top
any wild theories?
End of quote


maybe it is the speed of gods thoughts.


i saw an artist view of the universe as we know it galaxies and some sort of string connecting them together. tried to look it up again couldn't find it. but it looked just like DNA.
Reply #784 Top
maybe it is the speed of gods thoughts.
End of quote


Yea thats a pretty wild theory! lol but i think God exists beyond any constraints of time.

I do have a different wild theory but i will have to post it later when i have more time.
Reply #785 Top
There are several different ideas I have that kinda link together to form the foundation of my theory:

The first idea is the question as to wether or not the universe extends out forever? Lets consider a standard 30cm ruler, ok if I am standing here on Earth holding a 30cm ruler in my hand I can see that this ruler has two ends, a centre and many other points of measure along its length.
Now lets imagine that same ruler extended out forever in both directions, then I will first ask to consider at what point along that ruler is Earth situated? Since a ruler with no ends effectively has no centre or any other point of measure. To exist at some point on this ruler is simply impossible. So then I must conclude that either Earth and us and everything else in the universe does not really exist or the universe cannot be infinite.
However there is a third possible explanation which I feel is correct…. It is possible to exist at a point on a ruler that extends forever in both directions if time is eliminated from the equation! So the fundamental state of the universe is that time does not exist however due to the beauty of relativity, from our perspective, time does exist!!

Theory continues later on….. feel free to comment on above thus far.
Reply #786 Top
So then I must conclude that either Earth and us and everything else in the universe does not really exist or the universe cannot be infinite.
End of quote


space can be measurable and infinite. it just means your zero point is arbitrary. in other words, you can have infinity in both directions, but the 'starting point' or middle is a point of reference chosen for the sake of clear communication, not because it's the "real" center.

So the fundamental state of the universe is that time does not exist however due to the beauty of relativity, from our perspective, time does exist!!
End of quote


i dunno... that doesn't sound right at all, but i'm all jibbered up. i'm pretty sure what you can say (in line with special relativity) is from the internal point of view of a photon, graviton, or any massless particle, time "doesn't exist," at least not as a dimension.
Reply #787 Top
Dont we more or less imagine time? I find it interesting how often our sense of time changes with moods and such. Is it proven other things have a sense of time besides dark/light cycles?
Reply #788 Top
space can be measurable and infinite. it just means your zero point is arbitrary. in other words, you can have infinity in both directions, but the 'starting point' or middle is a point of reference chosen for the sake of clear communication, not because it's the "real" center.
End of quote


You should give it some more thought

i dunno... that doesn't sound right at all, but i'm all jibbered up. i'm pretty sure what you can say (in line with special relativity) is from the internal point of view of a photon, graviton, or any massless particle, time "doesn't exist," at least not as a dimension.
End of quote


I guess my ideas will become clearer when i get the time to add more, but thanks for speculating on what i wrote so far   

Dont we more or less imagine time?
End of quote


More than you might have guessed!

Reply #789 Top
I believe the universe exists in truth without time. What we perceive as time is merely a relative state which is real but also isn’t real. So if the universe exists in a state of ‘nil time’ then everything that has been or ever will be has already happened! I will call this the ‘picture of forever’. This picture of forever never changes because everything has already happened, however this picture of forever also changes constantly based on our actions in the present time!! Not that I enjoy contradicting myself but let me explain… lets say there is a boy who tries to cross the road and gets killed by a bus, now in the picture of forever, he has no descendants. However if instead that same boy decided to look up at just the right moment and avoid the bus then his descendants can be seen in the picture of forever. Now the trick is that time does not exist in the picture of forever so the previous fact of the boy getting killed never actually happened! The picture of forever never changes, but changes all the time!!! Am I making any sense yet?

More to come later - probably tomorrow!
Reply #790 Top
space can be measurable and infinite. it just means your zero point is arbitrary. in other words, you can have infinity in both directions, but the 'starting point' or middle is a point of reference chosen for the sake of clear communication, not because it's the "real" center.


You should give it some more thought
End of quote




what he means is with a ruler that goes in both directions for every. the ends of the ruler and the middle is where ever the observer is.
Reply #791 Top
god created time for man so that everything wouldn't happen at once.
Reply #792 Top
god created time for man so that everything wouldn't happen at once.
End of quote


I dunno, but it seems as though everything also dousn't happen all at once in heaven as well which is very perplexing if heaven is suposed to be timeless?
Reply #793 Top
maybe god lives under a different time line. like bacteria and humans.
Reply #794 Top
maybe god lives under a different time line. like bacteria and humans.
End of quote


I think of God as being like an elemental force of love. Love is a state of being that does not require time to exist, it is somthing that just 'is', always has been and always will exist.

Thinking of the timeline extending back and ahead forever is not too dissimilar a state as the ruler with eternal length i mentioned earlier!
Reply #795 Top
Thinking of the timeline extending back and ahead forever is not too dissimilar a state as the ruler with eternal length i mentioned earlier!
End of quote


i know
Reply #796 Top
here's something to think about, Plank time

According to the Big Bang theory nothing is known about the universe at time=0, though it is presumed that all fundamental forces coexisted and that all matter, energy, and spacetime expanded outward from an extremely hot and dense singularity. One Planck time after the event is the closest that theoretical physics can get to it, and at that time it appears that gravity separated from the other fundamental forces.
End of quote
Reply #797 Top
Plank Time YaY!

Also in the same realm, The Plank Constant, which was the bane of my existance in chem class and hence why it has been purged out of my memory!

Mystikmind;
The "ruler" anolgy falls apart as you just compared the universe to a number line, which is, by definition, measurable.

The size of the universe is infinitely defined by semantics. The universe, to use a slightly non-scientific definition, is essentially everything. All matter, energy, everything. Hence its not possible to travel beyond the edge of the universe as you would be extending it.

There's some interesting problems with the big bang theory, the largest being the obserrvation that the acceleration bewteen galaxies is increasing, whereas with big bang, the acceleration should be null or decreasing. While this doesn't rip the theory to shreds, and Big Bang is the most plausible theroy out there, it does indicate that there might be some factors that Big Bang does not consider or that we may not even be aware of at the moment.

I think one of the benifits of colonizing other systems would be the additional insight into astrophysics. We've essentially veiwed the entire universe from one point, out own solar system. By being able to look from two significantly different positions, we could see and learn quite abit about astrophysics. Imagine two hubbles in two different locations. IT would be like having two eyes (YaY for depth perception!)
Reply #798 Top
The size of the universe is infinitely defined by semantics. The universe, to use a slightly non-scientific definition, is essentially everything. All matter, energy, everything. Hence its not possible to travel beyond the edge of the universe as you would be extending it.
End of quote



the big question in astronomy today is.


if the universe is everything and the universe is expanding what is it expanding into.
Reply #799 Top
There's some interesting problems with the big bang theory, the largest being the obserrvation that the acceleration bewteen galaxies is increasing, whereas with big bang, the acceleration should be null or decreasing.
End of quote


ah yes, the universe's ever-mysterious dark energy (which is only related to 'dark matter' by naming convention - in essense, we have reasons to believe there should be more matter in the universe than we can observe, so we call that matter 'dark' - similarly, we know that some force is causing galaxies to accelerate away from each other, but we don't know what, so we call the presumed energy 'dark').
Reply #800 Top
Considering this "energy" is capable of accelerating galaxies, I would what it could do to a ship if we ever discovered enough about it to harness it?

That would be one fast ship.... although prolly a little too out there for the premise of your story



Now back to organizing my duty bag, woooo