Science Rapid Interstellar spaceflight, exploration and,colonization thread

[T.Neo]

Orion's Arm is Space Opera shoehorned into Hard SF and overdosed on transhumanism.

It does have a lot of interesting (if farfetched) physics concepts in it though. The so-called "void drive", basically an Alcubierre drive, is pretty accurate when it comes to what the Alcubierre concept seems to be limited to- namely, needing absurdly advanced infrastructure and not being able to exceed c.

Some of the other interesting concepts are ships that use warp bubbles for propulsion, but ride outside the bubbles, being pushed (or pulled) along with them.

Another, more "conventional" concept is a drive system which uses magnetic monopoles to convert matter to gamma rays; these gamma rays are then reflected by some sort of... stuff (supposedly a material made of magnetic monopoles, that is a perfect reflector), creating a highly efficient rocket propulsion system. It's kinda like using antimatter, except you don't need antimatter, just normal (abundant and cheap) matter, to be converted by the monoples. Such a spacecraft could, for example, be an interstellar ramjet, sucking up hydrogen from the interstellar medium and converting it to energy.

Generally though, this stuff tends to be farfetched to varying degrees, advanced technology or not. But... but... but... this kind of engine that converts any old matter to photons and then reflects them perfectly... darn it, that is a spaceship fanboy's dream...

The speculative biology of OA is pretty poor though, mostly it's just an attempt to have organisms that are as "alien" as possible, without regard to evolutionary laws or chemical/biological limitations.

The best speculative biology project I've seen is probably Snaiad, by a guy who goes by the 'pen name' Nemo Ramjet. Sadly the full Snaiad webpage has been down for some time, but some of his art can be seen at his DeviantArt gallery. Another speculative world I would recommend is Nereus, by Evan Black. The art is perhaps somewhat more stylised, but the evolutionary concepts follow along some of the same lines.

Another project I would recommend is Furaha by Gert van Dijk, which has apparently been around for around two decades, though not much information is available online. Nevertheless, the site has some interesting details in it, primarily several studies on the movement of different organisms. The Furaha blog is also very interesting, where the writer goes in depth about strange organisms, speculative concepts, and the plausbilities (and mostly implausibilities) of many different fictional organisms.

 

[vorthon]

I just find the idea that the only viable biochemistries are variants on the carbon/water setup so... depressing.

 

[T.Neo]

Why would one find it depressing? I don't. I'm alive!

The problems don't really relate to alternative biochemistries being impossible, but rather that they're at a chemical disadvantage to "familiar" life. And if you look at the chemical reactions, the sort of molecules you'd get, the cosmic abundances... you really will see that such life is at a disadvantage to carbon-and-water life.

Which would generally make such organisms evolving into complex forms less likely. You might get some interesting single-celled organisms, maybe some interesting sort of... slime mold stuff... but it's far more difficult for a methane organism to evolve into something like a fish or a spider.

And you could really have diverse variations on the carbon/water setup. For example, differing chirality, different analogues to DNA, entirely new and novel biomolecules that could be very valuable for various medical and biotechnological or chemical applications...

 

[vorthon]

Yeah, yeah, I'm familiar with all that stuff, but I'd like to see some really bizarre stuff. Neutron star life. Ecologies developed from Von Neumann Probes. Life in the atmosphere of a gas giant. Creatures that drink liquid ammonia. Stuff like that.

 

[T.Neo]

Yeah, well you can maybe make ammonia-drinking bacteria. But ammonia drinking flatworms would be orders of magnitude more difficult. And water-drinking bacteria will probably have less chance of dying of thirst...

You could have life in the atmosphere of a gas giant that uses water as a solvent, there are even regions in the atmospheres of Jupiter and Saturn where water could exist in liquid form. But life there faces other problems, such as biomass being lost to the abyss and highly turbulent wind patterns.

I don't know about neutron star life. We don't even know if it's physically possible for there to be neutron star life. Even if there is- somehow- it might also be relatively simple, existing as a minute atomic archean on a featureless plain of electron-degenerate matter.

You could probably make artificial life, self-replicating machines, and send them out to see how they evolve. There are even computer programs that simulate that sort of thing, in a very rudimentary fashion. Things might turn out the other way; nanotechnology, derived from already existing microscale machines with nanoscale components... bacterial cells!

 

[vorthon]

I'm just saying, considering how big the universe is, there's bound to be at least one world where a complex ecology has developed that uses liquid ammonia. Just sayin'.

 

[T.Neo]

You could also say that in the enormously huge universe, there could be a perfectly identical copy of the Lincoln Memorial on some moon somewhere.

Saying that there could be a megameter-wide gold necklace in orbit around a star in the Andromeda galaxy, means nothing; we want science. Calculations, estimations... are better than guessing.

It isn't impossible. It's just difficult. Carbon-water life already faces enough challenges that could prevent it from evolving into complex forms. Chemically disadvantaged organisms would face more challenges. Maybe there are worlds out there where there is... some sort of weird alternate life... but they'll be very few and far between. Already carbon and water are pretty common, after all.

 

[vorthon]

*Sigh.*

Oh well. Time to do an extensive overhaul of one of my sci-fi settings...

 

[T.Neo]

Sorry.

It hits everyone. It's a horrible, horrible feeling.

 

[vorthon]

Eh, It's about time I took another look at it, anyways. Haven't worked on it in months.


Also, VASIMR.

 

[T.Neo]

VASIMR won't work for interstellar travel over meaningful timescales. For a dV of only 0.1c, a VASIMR spacecraft with an exhaust velocity of 300 km/s would have to have a mass ratio of 2.5e43.

For a 100 ton spacecraft, that's the mass of several million galaxies. :facepalm:

VASIMR is also severely thrust-limited due to requiring an internal power source.

For interstellar spaceflight on a meaningful timescale, you are probably looking at fusion at the least, or maybe some sort of advanced fission drive, that we haven't come up with yet...

 

[Eagle1Division]

Here's a book I read through, it's about as much an easy read as a college textbook, but it covers, without lacking depth, alien biochemistries and does an extensive review of Terran biochemistry to get a good idea of what the requirements for life are on the chemical level and why Oxygen, Phosphorus, Carbon, etc. with Water are so well suited.

Especially interesting is the section on human DNA, and what non Carbon/Water based lifeforms would need at least to carry genetic information.

Oh, link.

To sum it up for you, the fluid needs to have polarity (surface tension), and the compounds that make up the life form need to involve chemicals that can make a chain similar to DNA, in that there's two strong backbones with weakly-bonded genetic code in-between. More or less, it needs to be almost identical to DNA.

That's just a traditional life form, though. You can go even more exotic and forego DNA, but you're on your own on how the lifeform will work if you do that. For example, a computer has no DNA, yet you could theoretically build one that reproduces, responds to stimuli, takes in energy, produces waste, etc.



As for the Alcuberrie drive, it's neat but it calls not just for exotic matter, but for huge amounts of exotic matter.

My bets are still on FTL travel by Higher Dimensional Rotation (Hyperspace, but nothing like the usual sense).
Doesn't require folded or curved space like traditional Hyperspace, doesn't call for exotic matter, or huge amounts of matter, doesn't call for huge amounts of energy, and it doesn't involve any paradoxes.

Catch is you need "electrogravitic coupling between [...] fields of specially conditioned em radiation and those that underlie gravity and
inertia", in other words, we need to fundamentally understand what gravity is before we can figure out how to use this FTL method.

As for the higher dimensions required, there's a lot of bets on String Theory and that says 11 Dimensions, and there's not a few theories that postulate more than the traditional 3 dimensions of space and 1 of time.

But overall, I find it far more plausible than any other FTL method I've seen.

 

[fsci123]

Im talking about sub-luminal travel here... FTL is slightly unrealistic i doubt we would EVER figure out how to travel at super-luminal speeds withing 200years...

 

[Eagle1Division]

*Sigh.*

Oh well. Time to do an extensive overhaul of one of my sci-fi settings...

Only if you're really tight about realism. Arthur C. Clarke is now Sir Arthur C. Clarke for his sci fi and it didn't drop exotic biochemistries just because they're not totally realistic. I wouldn't call it unrealistic, actually. When it comes to discovering things about the natural world, nature loves to pull surprises, and in that way being totally realistic and having humans only encounter what we expect to encounter is actually very unrealistic.

When it comes to alien life all we have right now is Earth, and working from a single data point is extremely unreliable. I'd say the line of realism is so blurred that a universe where non Carbon/Water life is just as common as Carbon/Water life is just as likely as a universe where there's only Water/Carbon life (at least to any practical extent), I certainly wouldn't count including non-Terran Biochemistry as unrealistic.

Also to consider is that Earth-like conditions are probably very rare, possibly even more rare than conditions on planets like Titan, Jupiter or Saturn. Given that life has a certain possibility of occuring for every unit of volume of workable habitat, that alone would almost ensure an abundance of non-Terran biochemistry in the universe.

You could have life in the atmosphere of a gas giant that uses water as a solvent, there are even regions in the atmospheres of Jupiter and Saturn where water could exist in liquid form. But life there faces other problems, such as biomass being lost to the abyss and highly turbulent wind patterns.

Ben Bova faced this in Jupiter by having the life-giving compounds condense from the atmosphere above and rain down through the layer that the life lived in, causing a constant supply of biomass to rain down.

And what about [ame=http://en.wikipedia.org/wiki/Sudarsky_extrasolar_planet_classification]Sudarsky[/ame] Class II Gas Giants? You don't need to go deep down to find liquid water on those.
The Sudarsky paper listed 47 Ursae Majoris b and Upsilon Andromedae d as fitting in this category.

Im talking about sub-luminal travel here... FTL is slightly unrealistic i doubt we would EVER figure out how to travel at super-luminal speeds withing 200years...

Don't be so Cynical. This kind of thing would come from advanced Physics, and that field can pop a surprise at any moment. It's more random than dice, really, it could be 20 years or it could be 200 years, I doubt it'll be even that much, though. Remember 200 years ago was the Early 1800's.

 

[T.Neo]

As for the Alcuberrie drive, it's neat but it calls not just for exotic matter, but for huge amounts of exotic matter.

The amount of exotic matter depends on how well you can do things. A revised version of Alcubierre's metric had something like a few grams of negative matter equivalent.

But I think it still required large amounts of positive matter/energy.

That's just a traditional life form, though. You can go even more exotic and forego DNA, but you're on your own on how the lifeform will work if you do that. For example, a computer has no DNA, yet you could theoretically build one that reproduces, responds to stimuli, takes in energy, produces waste, etc.

The problem here is: what sort of computer arises from abiogenesis? Maybe you can have some extremely novel system of biomolecules, but how would they work? Why don't we have any evidence or suggestion of anything of the sort potentially existing anywhere? What disadvantages does it have when compared to conventional life?

And even if you built an ethane-organism out of cryo-compounds, it still faces physics challenges. Like for example the speed at which chemical reactions take place. Such an organism could end up being painfully slow moving, slow thinking, and slow evolving.

But overall, I find it far more plausible than any other FTL method I've seen.

It sounds... elegant... but I think I'd need to hear more on the concept before my uneducated mind can draw any kind of ersatz conclusion.

Only if you're really tight about realism. Arthur C. Clarke is now Sir Arthur C. Clarke for his sci fi and it didn't drop exotic biochemistries just because they're not totally realistic. I wouldn't call it unrealistic, actually. When it comes to discovering things about the natural world, nature loves to pull surprises, and in that way being totally realistic and having humans only encounter what we expect to encounter is actually very unrealistic.

When it comes to alien life all we have right now is Earth, and working from a single data point is extremely unreliable. I'd say the line of realism is so blurred that a universe where non Carbon/Water life is just as common as Carbon/Water life is just as likely as a universe where there's only Water/Carbon life (at least to any practical extent), I certainly wouldn't count including non-Terran Biochemistry as unrealistic.

Also to consider is that Earth-like conditions are probably very rare, possibly even more rare than conditions on planets like Titan, Jupiter or Saturn. Given that life has a certain possibility of occuring for every unit of volume of workable habitat, that alone would almost ensure an abundance of non-Terran biochemistry in the universe.

Sir Arthur C. Clarke is renowned for his science fiction, not his science. Big difference there. The crew of the Leonov would have died of radiation poisoning before they even got to the monolith, for example.

If anything we can surmise that liquid water environments are most common in the galaxy. Even if we completely forget about terrestrial planets. In the outer system there are moons that are made of water ice. It's extremely common stuff; more common than methane/ethane or ammonia. And there's evidence to suggest that in some examples, at least, these moons have liquid water "mantles", under solid crusts of ice. We're pretty sure of it on Enceladus, and Europa shows signs of it as well. And it could very well exist on moons such as Ganymede and Callisto; Titan also shows signs of cryovolcanism (lava on Titan would be a warm mix of water and ammonia; scalding to any "alternate" life that would exist on the surface).

Life living in the depths of the Europan ocean would face difficulties, but they would be an order of magnitude less than those faced by methane-based life.

We see a lot of evidence that there was water on the surface of Mars in its early history, and it has been suggested that Venus had oceans as well. The question for a terrestrial planet is, how lucky do you have to be to keep your early environment stable, still having a habitable environment billions of years after your formation?

Maybe it should instead be "how unlucky do you have to be". Mars is, after all, tiny- around a tenth (!) the mass of Earth. And Venus, as well as being close to the Sun, has quite an odd rotation, and some odd geology going on.

Of course, there is nothing to say that a planet needs to be lucky. Or terrestrial. You could have any arrangement of planets; for example, you could have gas giants in the habitable zone, as with many of the systems we have detected. But some planets- the planets that life will exist on- will be lucky, like us.

That doesn't mean there will be a greater or smaller number of Titanian worlds. In our system, we have one Earthlike planet, and one... Titanian plan, uh, moon. Body. Celestial object. And yet we have multiple bodies (Titan included) that could harbour subsurface liquid water, and multiple bodies that had, or could have had, liquid water on their surface(s) in their early history. Were there any other Titanian moons back then? Do we have any evidence of them? Maybe we do, and we're just disregarding it because we're more interested in other stuff?

It isn't about biology, and surprises, and whatnot. It's about chemistry. We can already understand the chemistry of liquid ethane, dissolving stuff, or silicon forming molecules, and whatnot. And we can compare that with similar actions with chemicals found in "familiar" life.

And "alternate" biochemistries could well be more abundant than Earthlike ones. But limited to simple, monocellular or undifferentiated organisms that would probably be relatively uninteresting (yeah... I don't even know if you can call it "uninteresting", relatively has to be taken very, very strongly here).

Ben Bova faced this in Jupiter by having the life-giving compounds condense from the atmosphere above and rain down through the layer that the life lived in, causing a constant supply of biomass to rain down.

And what about Sudarsky Class II Gas Giants? You don't need to go deep down to find liquid water on those.
The Sudarsky paper listed 47 Ursae Majoris b and Upsilon Andromedae d as fitting in this category.

Yeah, I think Class II gas giants would probably be the best option for life on a gas giant. Among other planets, Mu Arae b is also probably a Class II gas giant...

But life there would still face raining biomass and turbulence issues. I've heard that, rather annoyingly, gas giants can be extremely turbulent, which would tend to tear apart any large flying creatures...

And I kinda like ballonts. :dry:

Don't be so Cynical. This kind of thing would come from advanced Physics, and that field can pop a surprise at any moment. It's more random than dice, really, it could be 20 years or it could be 200 years, I doubt it'll be even that much, though. Remember 200 years ago was the Early 1800's.

Woah there. We could discover a practical means of FTL travel in the next 200 years. Or we could not. It isn't technological advancement, it's scientific discovery. It is like trying to find hidden treasure, not like trying to mint coins.

I will always be optimistic about FTL. It would just be such an incredibly useful thing for exploring our universe. Of course there are things that, from our perspective, make it less likely... and then there are things that might make it possible somehow. But I really think the whole "FTL is unrealistic" and "all FTL is rubbish handwavium" is taking it far too far; FTL isn't either of those things. It's just highly, highly, highly speculative, and we're not quite sure that it's possible or not. That doesn't mean it is impossible.

But hey... you will always get the cynics and pessimistis. :dry:

I'm just stuck on a relatively boring little water-covered world in some random spiral arm of a galaxy. It's a nice place, but come on... it is like going to Britain and only seeing Glasgow! :facepalm:

Maybe it's just the biological version of "the grass is greener on the other side of the fence". But in this case, we haven't seen any other grass yet, and the fence is light-years of frigid vacuum.

 

[fsci123]

Well we already discovered FTL travel... The problem is that it is either impossible to make or impracticle...

 

[T.Neo]

No. For starters, "FTL travel" does not end at wormholes and Alcubierre drives. There doesn't seem to be anything truely seriously (in the turning into quark-gluon plasma sense) bad about using wormholes, but they'd be very difficult to produce. Whether they'd be impractical, time will tell.

But come on, it's FTL! Now you can cut your total travel time from years to maybe months!

It's totally worth it.

But the major problem with wormholes is that... they're static. You can't explore using a wormhole, only travel. You'll always have to ship wormholes to their destinations subluminally, and the promise of a free-range FTL propulsion system, would be incredibly attractive.

Who knows. Maybe there is some interesting spacetime metric thing, in the spirit of the Alcubierre concept, that does not suffer from such problems. We don't know. When it comes to stuff like this, you're in the realm of the furthest speculation on physics...

 

[fsci123]

Well my heart tells me we will discover FTL within 100years... My optimistic mind tells me we will discover FTL within 80years... My conservative mind tells me we will never discover FTL... Just speaking for all my minds...

 

[Eagle1Division]

The problem here is: what sort of computer arises from abiogenesis?

We did.

Maybe you can have some extremely novel system of biomolecules, but how would they work? Why don't we have any evidence or suggestion of anything of the sort potentially existing anywhere? What disadvantages does it have when compared to conventional life?

And even if you built an ethane-organism out of cryo-compounds, it still faces physics challenges. Like for example the speed at which chemical reactions take place. Such an organism could end up being painfully slow moving, slow thinking, and slow evolving.

They would work. We work, they can work, too. The basic requirement for life is that ability to have and replicate DNA. DNA could be any chemical structure with two strong backbones, weak disconnectable genomes, and existing in a polar solvent.

To be fair, we don't have any evidence or suggestion of any Carbon/Water life existing anywhere else, either, other than ourselves. And you can't use yourself for an argument in either direction, since we wouldn't be here to notice unless we're here... (There was a name for that, can't remember it...)
And interestingly enough, scientists actually have found life that uses an altered biochemistry than our own.
Arsenic-consuming life, on our own planet, that uses Arsenic in their DNA.
http://www.space.com/9631-arsenic-eating-bacteria-opens-possibilities-alien-life.html
http://www.mercurynews.com/san-mateo-county/ci_16763468?nclick_check=1
http://www.npr.org/2010/12/03/131785452/Arsenic-Eating-Bacteria-Challenge-View-Of-How-Life-Works
http://arizonageology.blogspot.com/2010/12/arsenic-consuming-bacteria-story.html

And there's nothing to say it would have any more or less challenges compared to conventional life. It would work very similarly. What I would like to find is this: I remember reading that someone had actually put together how an Ammonia (or was it Methane?) being would live, and according to his model, it would ingest hydrogen. This really caught NASA's attention when they discovered that the lower atmosphere of Titan is lacking hydrogen to a huge unproportional extant.

And finally, it doesn't matter what the overall energy level is, what matters is how energetic the chemical reactions are. Temperature alone doesn't decide how energetic a chemical reaction is. Point in case; at room temperature you can mix vinegar and baking soda, or gasoline and pure oxygen. Same temperature, drastically different reaction rates.
An example applying to known life is plants. We live on a timescale many times faster than plants, yet we both exist at the same temperature, so there's no reason to assume that because they'd be cold they'd be slow, too.

---------- Post added at 02:56 AM ---------- Previous post was at 02:51 AM ----------

Sir Arthur C. Clarke is renowned for his science fiction, not his science. Big difference there. The crew of the Leonov would have died of radiation poisoning before they even got to the monolith, for example.

Yeah, Science Fiction. I was talking about Vorthon's message:

*Sigh.*

Oh well. Time to do an extensive overhaul of one of my sci-fi settings...

Science Fiction, not science.

Your other points are good, generally if I don't quote that means you've got a point.

 

[fsci123]

Well it all depends on abbundance... Hydrogen super abundant... Oxygen is more abundant than nitrogen than chlorine... Phosphorous is more abundant than arsenic... Nitrogen has more "flexibility" than phosphorous... Iron is super abundant as a metal... Carbon is more flexible than silicon...
So with this knowlede of abundance and chemical properties we can predict what life on other planets will be like in a chemical sense... I doubt there will be a hyperintelligent being that lives off uraniumoxide and breathes radon gas...