# Interstellar space travel: which designs have the best chances of getting...



## matt-browne-sfw

... implemented by the end of this century?

Here’s the Wikipedia definition from Interstellar travel - Wikipedia, the free encyclopedia

Interstellar space travel is unmanned or manned travel between stars. It is tremendously more difficult than interplanetary travel due to the vastly larger distances involved. Given sufficient travel time and engineering work, both unmanned and generational interstellar travel seem possible, though representing a very considerable technological and economic challenge unlikely to be met for some time, particularly for crewed probes. NASA has been engaging in research into these topics for several years, and has accumulated a number of theoretical approaches.

Wikipedia lists several designs (including a human crew):

A: Slow interstellar space travel based on generation starships (normal lifespans)
B: Extented human lifespan to reduce number of generations on the starship
C: Sleeper ships with hibernating human passengers (using cryopreservation)
D: Embryo space colonization approach (using artificial wombs and androids)
E: Fast sub-light-speed travel using light sails (slow but long acceleration process)
F: Fast sub-light-speed travel using fusion engines (e.g. based on Bussard ramjet)
G: Fast sub-light-speed travel using antimatter engines
H: Locating and using a wormhole (as a “shortcut” to get to a distant star)
I: Creating and using an artificial wormhole
J: Faster than light travel based on “warped” spacetime or other currently unknown concept

A – E: are all “slow” approaches with trips that can take thousands of years
F + G: are all “fast” approaches with trips that can take many dozens of years
H – J: are all “extremely fast” with trips that can take months or years

Can you name your TOP 3 designs which have the best chances of getting implemented by the end of this century?

Here are mine:

TOP 1 - D: Embryo space colonization approach (using artificial wombs and androids)
TOP 2 - B: Extented human lifespan to reduce number of generations on the starship
TOP 3 - C: Sleeper ships with hibernating human passengers


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## Dave

I would think that only option A is currently available, the others being science fiction. Even that option would be very expensive, technologically challenging and would take such a long time that I doubt they would even try. At the present time there is no great need to do this; overpopulation and resource depletion have not driven us to that stage yet. Even if they did try a generational ship, chances are that one of the other faster options might become possible within that time-frame, leapfrogging them to the destination more quickly. That sounds like an idea for a story actually!


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## chrispenycate

How about steady expansion away from the sun, until the space stations deep in the Oort cloud are essentially star ships, getting reaction mass from so far outside the sun's gravity well (well, not outside it, obviously, as it essentially never stops, but so shallowly in it that escape energy is negligible) - slow obviously.
Vacuum energy; obbviously, since  conservation of momentum holds, this involves harrying reaction mass (a bit like the antimatter drive) mid speed
Some new physical principle: perhaps gravity control, which would allow the transfer of momentum to other celestial bodies, in particular the sun( no way of predicting the probability of this, as it's original research, so the results are, by definition, unknown.  Speed? Equally dependant on whatever system comes out of the research.
The light-sail system only works if you have a laser launching system - solar energy drops off too fast (even then, it'sonly good for short trips; feedback gets dodgy when the light system takes a couple of years do do a return trip, and slowing is much more difficult than accellerating, but it's a really nice theory, needing no reaction mass, and the power plant can stay at home with the service engineers (getting home, of course involves building a similar power plant at the destination star. And the sail for a payload involving a life support system for a centuryor so is enormous - bigger than a planet (thouggh weighing relatively little)
Hibernation sounds good. However hibernation is metabolic slowdown (maybe a hundred times or so) but no total stoppage. Still, cryonic research will be going ahead for other reasons (well, so will research on artificial placentas for your embrionic transport) 
We're a long way from any of the systems required; but we're a long way from requiring them, too. But don't think that any of these are going to help Earth's population problems; even the space elevator running continuously could only increase the population in space, not reduce it on Earth; you'll have to use more traditional methods for that.


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## Pyan

Generation ships may sound like a reasonable idea - but they don't have a very good record in SF....


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## matt-browne-sfw

Dave said:


> I would think that only option A is currently available, the others being science fiction. Even that option would be very expensive, technologically challenging and would take such a long time that I doubt they would even try. At the present time there is no great need to do this; overpopulation and resource depletion have not driven us to that stage yet. Even if they did try a generational ship, chances are that one of the other faster options might become possible within that time-frame, leapfrogging them to the destination more quickly. That sounds like an idea for a story actually!



Thanks all for your input so far. Dave, why do you think A is more realistic than D? Generation starships would have to deal with hundreds of generations all living on the very same ship. My personal opinion is that the embryo space colonization concept will be easier to implement.


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## Dave

matt-browne-sfw said:


> Dave, why do you think A is more realistic than D? Generation star ships would have to deal with hundreds of generations all living on the very same ship. My personal opinion is that the embryo space colonization concept will be easier to implement.


With the current leaps forward in infertility research you are probably right. But who would care for these embryos and keep them secure? Would a machine be reliable enough to do so on such a long timescale?

And "Hundreds of generations" - at 20 years per generation that is 20,000 years +

Surely, our very first steps would not be quite so far?

Frankly, I can't see them doing this until we develop a much faster drive, or there is some cataclysmic reason for leaving Earth.


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## Parson

Dave said:


> Frankly, I can't see them doing this until we develop a much faster drive, or there is some cataclysmic reason for leaving Earth.



Agreed. Until we have some drive that can push a payload up to and back from some significant fraction of the speed of light (10% perhaps), 20,000 years is about what it would take to reach the next star at present acceleration/fuel possibilities. The only present technology that holds any real promise would be the ion engine but with the current paranoia about anything "atomic" it is unlikely to get the kind of research and development necessary in the foreseeable future.


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## matt-browne-sfw

Dave said:


> With the current leaps forward in infertility research you are probably right. But who would care for these embryos and keep them secure? Would a machine be reliable enough to do so on such a long timescale?
> 
> And "Hundreds of generations" - at 20 years per generation that is 20,000 years +
> 
> Surely, our very first steps would not be quite so far?
> 
> Frankly, I can't see them doing this until we develop a much faster drive, or there is some cataclysmic reason for leaving Earth.



Well, with all the talk about a "technological singularity"... don't you think it's a bit simpler to build androids capable of raising children (belonging to the species of friendly AI).

In my book I tried to show that the embryo space colonization concept could work...


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## Mr Baatard

I think this century will see AI using option E, maybe F.  We'll send robots into space until we figure out how to get there in reasonable timeframes.  

Humans won't take the plunge into space unless 1.) we're evacuating, or 2.) we get a handle on gravity wells.  I guess the latter would be option J, with the former being whatever we could get off the ground in a hurry.


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## Dave

matt-browne-sfw said:


> ...don't you think it's a bit simpler to build androids capable of raising children (belonging to the species of friendly AI)...


I'd never thought about it before. Obviously, we don't have AIs that would be capable of rearing children right now, but maybe in the future??

The only thing I would say is that they would need to be extremely human-like androids. Children and Babies learn everything in their development from imitating adults, right from first smiles and facial expressions, to walking, talking, eating, toilet training, to schooling and studying.

I think that the things that would make such androids capable of space-travel, when humans were not, might make them just too different, too odd, for that task of child development. Even the longevity/immortality issue alone would cause a problem.


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## iansales

George Mann's *The Human Abstract* takes this as its starting point - it's set on a colony world whose founders were raised by AIs.

And for what it's worth, I don't think we'll see any interstellar space travel this century. The distances are too vast, the environment is too dangerous, and the cost is too high. We have plenty to explore and exploit in our own planetary system, and it's going to be several centuries before that becomes routine.


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## matt-browne-sfw

Dave said:


> I'd never thought about it before. Obviously, we don't have AIs that would be capable of rearing children right now, but maybe in the future??
> 
> The only thing I would say is that they would need to be extremely human-like androids. Children and Babies learn everything in their development from imitating adults, right from first smiles and facial expressions, to walking, talking, eating, toilet training, to schooling and studying.
> 
> I think that the things that would make such androids capable of space-travel, when humans were not, might make them just too different, too odd, for that task of child development. Even the longevity/immortality issue alone would cause a problem.



No, indeed we don't have AIs that would be capable of rearing children right now. But given the accelerating scientific progress, don't you think it's likely to appear around the year 2045 or later?


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## iansales

We don't even know if AI is possible. It may never happen. If, on the other hand, we use an extremely sophisticated computer... I'm not convinced even that level of sophistication is possible. There are physical limits, after all - and we've already reached those for magnetic media.

The other problem you have is ensuring the viability of the embryos you've sent out to colonise other worlds. Outer space is a harsh environment, and humanity is coddled on Earth.


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## Parson

I would be equally concerned about the time when the children become teenagers with little sense, but sophistication enough to circumnavigate the AI. Raising children is an art and not a science. I really doubt AI's raise to the level of art.


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## speedingslug

Creating and using an artificial wormhole, 'stargate' would be the best solution but it will be many years if ever that anyone travels through hyperspace. Even faster than light travel is still too slow. 
A planet has been found 41 light years away that is in the right orbit to support life, it's a gas giant but has some promising moons. Space is just too big for us to understand how insignificant we really are.


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## matt-browne-sfw

Parson said:


> I would be equally concerned about the time when the children become teenagers with little sense, but sophistication enough to circumnavigate the AI. Raising children is an art and not a science. I really doubt AI's raise to the level of art.



I'm concerned too. Suppose AI is strong enough. What if the all children had identical twins on Earth? They don't travel, but we could learn how they behave as teenagers. We could try to make predictions about the children traveling as frozen embryos. Well, that raises a whole set of ethical questions, doesn't it?


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## Parson

This sounds more like a sociological experiment than a control group. We have all of the old battleground issues of nurture vs. nature here. Suffice it to say that I believe that nurture is at least as important as nature in determining the kind of adult which will arise from a birth. 

I recall a SF book many years ago that had this kind of embryo star ship as a center feature. But the author did not deal too much with the idea of growing up, chiefly he had the "robots" -- AI's in our terms here. Run things according to plans until the children reached their early teens, and they took over but the robots told the children that certain things like the setting up of a nuclear  power plant could not be diverted from their regular programing or they would die. Which they believed and let the robots do that part of the building according to the original plan. 

Of course, being a typical liberal author the sociological point he made in his book is that only the smallest amount of regulation is good in a life (the new world had no central government and was relatively easily able to defeat the later US? star ship (which wanted to make the planet and colony and enter into the wars of earth) and would have to deal with Russian and Chinese in coming years. 

History seems to teach us that there is a delicate balance between freedom and civil control needed for the people of the society to prosper.


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## Dave

Parson said:


> History seems to teach us that there is a delicate balance between freedom and civil control needed for the people of the society to prosper.


Also studies show that we all learn this delicate balance between freedom and self control around the age of 3. This is the "terrible-twos" period of tantrums that anyone who has had kids will recognise. It is when parents fail to discipline their kids at this age that the kids grow up with problems with authority. Now are we suggesting that we might leave this to a robot instead?


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## Parson

Dave,

We are a little off topic here, but oh well. (Does this mean that I did not have enough discipline as a 2 year old and so grew up permissive?)

I am unaware of the studies you speak of, but their logic would seem prohibitive. There are such delicate clues that determine the difference between "childish behavior" and challenges to "authority" that a good share of humans don't pick them up. For an AI to pick them up seems unlikely, and if "it" should I am not sure that having a completely sensible response to every situation would make for the best of learnings in childhood. Somewhere along the line we have to have the sense that this life is not often fair. Societies are not predictable chemical reactions and never will be.


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## dustinzgirl

OK I know this is a more serious thread....

But, in one of my stories I thought of the problem of space travel, and since I don't know jack about science, or space, I came up with a sort of magic bubble. It would be able to hold time and atmosphere, like a mini planet, and basically 'bounce' through space by going in between dimensional points in space to reach its destination. I know, its not really possible, but if I were smart enough to work out the finepoints, I thought it would be pretty cool


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## Dave

Parson said:


> I am unaware of the studies you speak of, but their logic would seem prohibitive.


I don't have a study to hand but Google "child Development" "terrible twos" and you will get pages of websites with advice for parents. It is a testing time for parents (mothers) as the children begin to learn to assert themselves and their personalities emerge. One of those sites says "Your child is using one of the only tools he has–noncompliance in what he perceives as a battle for a sense of self and power." Children who parents cave in to and allow them to do whatever they like, continue to believe they can do whatever they like for the remainder of their lives. Throwing a tantrum every time you fail to get your own way is a behaviour difficult to unlearn once learned.

My point is that if parents find that hard to cope with, how hard would it be for an AI. 

Even harder to deal with would be the emotional problems of teenagers.

I don't think it is off-topic because I can't see an AI being able to bring up children in the very near future. The other options might be easier to achieve.


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## Parson

Dave said:


> I don't have a study to hand but Google "child Development" "terrible twos" and you will get pages of websites with advice for parents. It is a testing time for parents (mothers) as the children begin to learn to assert themselves and their personalities emerge. One of those sites says "Your child is using one of the only tools he has–noncompliance in what he perceives as a battle for a sense of self and power." Children who parents cave in to and allow them to do whatever they like, continue to believe they can do whatever they like for the remainder of their lives. Throwing a tantrum every time you fail to get your own way is a behaviour difficult to unlearn once learned.



This is so true! I have a 2 year old grandson who lives with us half time and his tantrum throwing "No" yelling is very hard to take. It is almost always necessary to let the little "yeller" discover that the tantrum is not going to gain him anything more or different; but that asking politely has a chance of doing that. 

On the other hand it is necessary to see life from the child's eye as well. So  much of the world is incomprehensible and so completely out of his understanding or control.

On the whole I think that we agree that the raising of the children might be one of the greatest downfalls in the embryo method of stellar travel. What might have seemed at first brush to be one of the lesser problems might well be the one that makes this method very unlikely to be used by humans.

Cavet: It may be that AI's would do a better job than a lot of parents.


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## matt-browne-sfw

Parson said:


> This sounds more like a sociological experiment than a control group. We have all of the old battleground issues of nurture vs. nature here. Suffice it to say that I believe that nurture is at least as important as nature in determining the kind of adult which will arise from a birth.



There's an even more ambitious idea: instead of frozen human embryos just take a collection of CD-Rs on the trip. Each CD-R stores the genome of a human being living on Earth now. Or take a large harddrive use some compression algorithms (I've each genome would only require 100 megabytes if compressed).

In addition to artificial womb devices you also need the technology to transfer the genome into a generic fertilized egg that just needs the DNA injected.


And you still need the androids to raise the children.


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## Parson

matt-browne-sfw said:


> There's an even more ambitious idea: instead of frozen human embryos just take a collection of CD-Rs on the trip. Each CD-R stores the genome of a human being living on Earth now. Or take a large harddrive use some compression algorithms (I've each genome would only require 100 megabytes if compressed).
> 
> In addition to artificial womb devices you also need the technology to transfer the genome into a generic fertilized egg that just needs the DNA injected.
> 
> 
> And you still need the androids to raise the children.



Wow! Science on that level would seem to need the equal of the science needed to get a true atomic star drive (I'm assuming a 10% speed of light as a minimum for actually traveling with a living crew to a new star.) If the latter were possible, I wouldn't want to mess with the former for sociological  reasons listed above.


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## matt-browne-sfw

Parson said:


> Wow! Science on that level would seem to need the equal of the science needed to get a true atomic star drive (I'm assuming a 10% speed of light as a minimum for actually traveling with a living crew to a new star.) If the latter were possible, I wouldn't want to mess with the former for sociological  reasons listed above.



I admit it's truly visionary... but that's the great thing about science fiction, isn't it?


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## Parson

matt-browne-sfw said:


> I admit it's truly visionary... but that's the great thing about science fiction, isn't it?



So true! But like most things "your greatest strength is also your greatest weakness." For SF that amounts to pushing an idea so far that it loses any touch of reality. I thought the later Dune sequels did that. I've never even been tempted to read those "prequels." 

When it comes to Star Drives it seems SF deals with them inversely proportionally to their connection with understood physics. So we have generation ships or embryo ships rarely making an appearance, but warp drives, private star ships, and interstellar matter transfer making regular appearances.


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## Steve Jordan

If the point is to basically get humans, _any_ humans, to another star system, I could see D, powered by either E, F, or G, by the end of this century.  

I base that on the idea that an embryonic ship could be incredibly compact, needing no life support other than embryonic preservation, therefore being able to travel fastest with whatever drive technology you used.  Once it reached a viable destination (and it would be easier to leapfrog around, if the first destination did not suit, until a viable planet was found), it could presumably land and use the local resources to construct its artificial wombs and nurturing facilities, and grow humans only after they arrive.

I can't see the logic in living people trying to make such a trip at all, asleep or awake/generational, unless it was a dire emergency (Earth is finally dying, about to be asteroid-food, etc) and Earth's inhabitants insist on trying to rough-it in space.  Even if this was the case, I wouldn't even try to get to another planet: I would put everyone in orbit around or near Earth, and try to repair the terrestrial damage enough to return to it.  I'd bet that could be done a lot faster, and with less energy, than trying to get to another planet we-know-not-where (the "Bird in the Hand" theory of human preservation).


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## Steve Jordan

matt-browne-sfw said:


> Well, with all the talk about a "technological singularity"... don't you think it's a bit simpler to build androids capable of raising children (belonging to the species of friendly AI).
> 
> In my book I tried to show that the embryo space colonization concept could work...



Matt, if you've never been exposed to it, try and find a series of manga called _2001 Nights_, written by [SIZE=-1]Yukinobu Hoshino.  An excellent example of embryonic travel and android raising of children (as well as a believable map of development of Man's ability to eventually travel the stars, and what he is likely to find).[/SIZE]


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## Montero

Dave said:


> Even if they did try a generational ship, chances are that one of the other faster options might become possible within that time-frame, leapfrogging them to the destination more quickly. That sounds like an idea for a story actually!



Its the background for RA MacAvoy's "The Third Eagle" .  A very good story it is too.

Though it is a sleeper ship overtaken by faster technology not a generational ship.


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## Montero

Raising children from embryo

There is an interesting take in The Legacy of Heorot by Larry Niven, Jerry Pournelle, and Steven Barnes.
They arrive on planet largely by sleeper technology (in the Dragons of Heorot) and have a massive cargo of frozen embryo (or sperm plus egg, can't remember which now).  The adults who survive the journey have their own kids, plus they defrost a number of babies from the cargo and raise them as well.
However, said kids finish up feeling a separate group and thereby hangs trouble. (Don't want to go into a spoiler here.)


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## RVM45

.....No one mentioned the Bussard Ramjet. If I remember correctly, it is capable of accelerating up to about .38C. Oddly enough, it cant go any faster because of "Wind Resistance".(At 38% of lightspeed, even 1 atom of hydrogen per cubic yard starts to add up.)

.....I do have an observation though- many folks seem to think that Einstein's discovery that the speed of light is an unsurpassable limit, dashed many hopes of travelling to the stars.

.....Reality check people. If they came up with a device tomorrow, that let you travel through space AS-IF it was completely Newtonion; accelerating to as many C as you had delta V to- where would you get the delta V? You wouldn't be one step closer to the stars than we are right now.(although undoubtedly such a weird process would certainly contain beaucoup unintended and quite possibly unforseen consequences. One of the side effects might get you to the stars- if one of the others didn't blow up the known universe first...)

.....RVM45


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## Steve Jordan

RVM45 said:


> .....No one mentioned the Bussard Ramjet. If I remember correctly, it is capable of accelerating up to about .38C. Oddly enough, it cant go any faster because of "Wind Resistance".(At 38% of lightspeed, even 1 atom of hydrogen per cubic yard starts to add up.)



It's item "F" of the opening item, fusion engines, e.g., based on Bussard Ramjet.  My suggestion was of an embryonic ship using one of 3 propulsive systems, including F.


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## RVM45

.....Don't know how I missed that. Maybe because you confused me by putting it right out in plain sight that way.

.....My bad.

.....RVM45


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## Steve Jordan

Of course, I still hold out hope for "J," "warped space" or other FTL method.  

I worked out the details (sshhh) for a transportation system that ably bypasses the limits of the speed of light, and which seems not only theoretically plausible based on the tenets of quantum theory and experimental data I've dug up, but within the realm of practical possibility for a piloted space craft to use... maybe even by end of century!  I don't believe this method has been suggested before, though admittedly there's a lot of SF out there that I haven't seen yet.  But it's a very elegant system, so I'm looking forward to messing with it.

I plan to apply it in a future novel (not the one I'm on now, which takes place firmly rooted on Earth, but possibly the next story).


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## Steve Jordan

Well, I see no one's been in here for awhile.  Just thought I'd mention that I used my drive system in my novel Verdant Skies, and it turned out to be my most acclaimed novel yet, partially for the inventive and believable use of science.


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## John Thiel

Make mine a spacewarp.  A ship should be suspended in an energy-field and transmitted (like radio waves) to a new destination. But of course there has to be a receiving area to do that---hence, I think, the alien make of the spacecraft in SGU. They seem to beam across on solar attraction.


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## chrispenycate

John Thiel said:


> Make mine a spacewarp.  A ship should be suspended in an energy-field and transmitted (like radio waves) to a new destination. But of course there has to be a receiving area to do that---hence, I think, the alien make of the spacecraft in SGU. They seem to beam across on solar attraction.



But radio waves travel at light speed, so even if the occupants of your vessel experienced no duration, if the star the ship was travelling to was twenty odd light years distant, it'd be forty years before the folks back home new they'd arrived.

I take a spacewarp to eliminate distance entirely, fold the cosmos so that two points that are separated by light years when travelling through conventional space become contiguous. Obviously this requires manipulating a supplementary dimension, and the only thing that shows any signs of doing that for the time being are intense gravitational fields; but it's not mathematically impossible.


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## Deathpool

I'd choose a wormhole.


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## John Thiel

By the way, if those are to be called wormholes, what is considered to be the worm?


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## Steve Jordan

John Thiel said:


> By the way, if those are to be called wormholes, what is considered to be the worm?



You are... after you're reduced to your constituent particles and squeezed through the hole.

I don't know why wormholes are so popular lately, or why anyone believes we can either survive intact when traveling through a wormhole... or somehow reconstruct our forms, particle by particle, to their original intact positions before we went in.  The amount of processing power required to do that must be as practically impossible as using brute-force rocket thrust to get to light speed.

And that doesn't even include the idea of actually being able to wrangle the wormholes themselves, to set their end points and actively maintain them over a significant period of time!  Might as well use a firecracker to try to push the Earth out of orbit...

For me, I don't discount the possibility that there are aspects of spacetime that we still don't know much about, and that one of those aspects may give rise to a way of moving from place to place in a unique way.

I keep coming back to experiments that have used lasers to fire controlled bursts of energy at photons, resulting in their apparently disappearing, and reappearing in another location, in a span of time so short as to mean *they traversed the distance faster than light could have traversed the same distance*.  I think some type of FTL travel may come from this essential finding, which is what I based my novel's transport system on.


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## John Thiel

I'll pick up VERDANT SKIES if I run across it at a bookstore.


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## Rodders

Considering the violent nature of mankind, i wonder if we'd survive a generation ship? 

BTW: The generation ship was my vote.


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## Steve Jordan

John Thiel said:


> I'll pick up VERDANT SKIES if I run across it at a bookstore.



_I hope not_; it's only available in ebook formats.



Rodders said:


> Considering the violent nature of mankind, i wonder if we'd survive a generation ship?
> 
> BTW: The generation ship was my vote.



Hm... civil war on a generation ship?  Now there's a story in the making!...


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