Debunking Interstellar Travel: Separating Fact from Fiction

[bugatti79]

Hi Folks,

What is your opinion on this article? It suggest that interstellar travel is a fantasy.

http://www.scientificamerican.com/article/interstellar-travel-as-delusional-fantasy-excerpt/#

Yet, I read articles about institutions like NASA investing in various conceptual propulsion systems.

Are they wasting their time?

Regards
B

 

[Borg]

With today's technology - yes, it's a fantasy. The article spells it out pretty clearly.

 

[phinds]

I haven't looked at the article but you'll find many threads on this forum pointing out all the issues that make it a fantasy.

 

[DrStupid]

What is your opinion on this article?

The argumentation is limited to humans traveling with existing or at least prospected technology at relativistic speeds in order to colonize an exoplanet (possibly occupied by hostile aliens!) and to get a return of investment. Finally the conclusion derived from these shortsighted assumptions - that such a project would be impossible and foolish - is presented as universally valid. I simply don't like it.

 

[bugatti79]

but assuming we have the technology it would still be impossible to travel through all that dust without damage? To me, that is the ultimate limitation IMHO!

 

[phinds]

but assuming we have the technology it would still be impossible to travel through all that dust without damage? To me, that is the ultimate limitation IMHO!

That seems to be a self-contradictory statement. "Having the technology" INCLUDES having a way to get through the dust.

 

[bugatti79]

I should choose my words carefully. I meant "propulsion technology" that major firms are investing in etc at the moment.

 

[phinds]

I should choose my words carefully. I meant "propulsion technology" that major firms are investing in etc at the moment.

OK, but propulsion technology is just one of many things that would be needed.

 

[Borg]

I should choose my words carefully. I meant "propulsion technology" that major firms are investing in etc at the moment.

Even this is an overstatement. The only currently possible propulsion technology improvements are things that can help to get to the other planets quicker. Nobody is working on an interstellar drive nor is it technically feasible. We're stuck in this solar system unless we discover something fundementally different about physics.

 

[Drakkith]

We're stuck in this solar system unless we discover something fundementally different about physics.

Or we have a really, really good reason to leave.

 

[Rubidium_71]

Necessity is the mother of invention. The tone of the article suggests we should've stayed in Africa, a voyage to another continent would be extremely dangerous and there would be no guarantee of a profitable return. I agree that there are monumental challenges that we may never overcome. It also seems more likely that our machines (rather than humans themselves) will be the first visitors to other star systems. Especially given the current direction of exploration in our own Solar System - we've sent our machines to the outer reaches, rather than going ourselves.
I agree with Drakkith, if people had a good enough reason to flee the Earth they just might come up with something. While current science and technology are inadequate, who knows what future innovation will bring?

 

[Borg]

Necessity is the mother of invention. The tone of the article suggests we should've stayed in Africa, a voyage to another continent would be extremely dangerous and there would be no guarantee of a profitable return. I agree that there are monumental challenges that we may never overcome. It also seems more likely that our machines (rather than humans themselves) will be the first visitors to other star systems. Especially given the current direction of exploration in our own Solar System - we've sent our machines to the outer reaches, rather than going ourselves.
I agree with Drakkith, if people had a good enough reason to flee the Earth they just might come up with something. While current science and technology are inadequate, who knows what future innovation will bring?

It sounds like you're saying both that we should do it and it can't be done.

 

[Rubidium_71]

I'm admitting it can't currently be done. I'm not saying it's outside the realm of all possibility. The message of the article seems to say "give up on any extra solar endeavor." Seems a little defeatist to me.

 

[DrStupid]

Or we have a really, really good reason to leave.

It would need a really, really good reason not to leave. We will start colonizing the solar system as soon as we learn to permanently live in space. After planets, moons and asteroids our descendants will colonize the Kuiper belt and finally the Oort cloud. At the outer edge of the Oort cloud they are almost halfway to the next star. Drifting around the Sun (which is just a bright star out there) or to another star makes no difference for such a colony. They have no reason not to take the last step into another system with new resources. Always preventing all deep space colonies from leaving the Solar system would be hard work - even for god-like entities. And there is no reason to do so. Trying to reach the other stars first makes much more sense.

 

[Borg]

It's like a race of intelligent ants building a bridge across the atlantic.

 

[Hornbein]

Hi Folks,

What is your opinion on this article? It suggest that interstellar travel is a fantasy.

http://www.scientificamerican.com/article/interstellar-travel-as-delusional-fantasy-excerpt/#

Yet, I read articles about institutions like NASA investing in various conceptual propulsion systems.

Are they wasting their time?

Regards
B

It seems like a fantasy today. But who knows the technology of the year 44521?

 

[rootone]

It seems like a fantasy today. But who knows the technology of the year 44521?

Fair comment, but well established physics will still be the same.
At present it's incomprehensible what kind of engine could accelerate a fairly massive ship to a substantial fraction of light speed,
but it's not impossible in principle.
I think the really insurmountable problem will be interstellar dust particles which can't be seen before the ship hits it,
and when it does hit, it would release energy in the order of a fair sized nuke, (directly on the surface of a fragile habitat).

 

[Hornbein]

Fair comment, but well established physics will still be the same.

probably. But they may have an entirely different approach to the problem. Besides, I'm sure there are all sorts of consequences of known physics of which we are unaware. If 20,000 years isn't enough, how about 20,000,000 years?

 

[MacRudi]

Hi Folks,

What is your opinion on this article? It suggest that interstellar travel is a fantasy.

http://www.scientificamerican.com/article/interstellar-travel-as-delusional-fantasy-excerpt/#

Yet, I read articles about institutions like NASA investing in various conceptual propulsion systems.

Are they wasting their time?

Regards
B

It is a waste of time to read this article
Many people are working on problems of interstellar flights since the 1970s
http://www.icarusinterstellar.org/project-daedalus-background/

If you look only on propulsion technology, then we have many new theoretical and even now practical ideas since the 1970s.
We can think of now for an electroplasma drive which can be 300 km/s fast
We can think of later for a fusion drive which can be about 10 % of light speed (look at Andreas Hein and his Ghostship he designed and was awarded for in 2013). The design includes not only the fusion technology. It is also the complete spaceship with electromagentic shields and Berilium surface against dust and space radiation. Old conceptions were with 60 cm aluminium walls.
This is only the technology with man more things to think about, but many people are also working on sociology and psychological problems for a generationship.
But I think (it's my opinion and not of the most interstellar enthusiasts) that it makes sense only if we have a true WARP drive. Many things would be easier. Not only because we could fly much faster than light. But then we have only one really big problem and this will be energy production for a WARP drive. We need 500kg Antimatter for a 10-meter WARP bubble with an effective velocity of 10c, if we calculate for the ordinary alcubierre drive in oscilation. So we need an matter/antimatter reactor like in Star Trek. But where to get 500 kg antimatter? How much energy we would need to produce 500 kg antimatter in LHC? What would it cost?
But anyway
I still believe that we can solve all problems in time. And I think this will be not too far in time. We have many conceptions and ideas. And if we have all the theoretical ideas then we can take over in practice 50 years later. The biggest problem is only the money. And the capitalististic system is not efficient enough to get money for such a project before in 200 years (serious calculations based on calculations of ISS of Andreas Hein University munich)

 

[newjerseyrunner]

I saw this article earlier: http://www.zmescience.com/space/lasers-mars-travel-04232/ I have doubts about some of the time estimates, but I think this will probably be our first real propulsion system out of the solar system. A space based laser in solar orbit could theoretically push a small craft to a fraction of the speed of light and send it on a flyby mission to nearby stars.

 

[|Glitch|]

Even this is an overstatement. The only currently possible propulsion technology improvements are things that can help to get to the other planets quicker. Nobody is working on an interstellar drive nor is it technically feasible. We're stuck in this solar system unless we discover something fundementally different about physics.

Actually, there is a propulsion technology that can do both. A propulsion system with the ability to generate 1 g continuous thrust would get us to planets quicker (Mars, for example, in under 3 days) and propel us to the stars. The biggest problem for interstellar travel would be the fuel. We couldn't bring along enough fuel to make it to even the closest star, even if the engines were 100% efficient and we used anti-matter. Which means that the fuel would have to be collected/manufactured along the way.

 

[Sei]

Actually, there is a propulsion technology that can do both. A propulsion system with the ability to generate 1 g continuous thrust would get us to planets quicker (Mars, for example, in under 3 days) and propel us to the stars. The biggest problem for interstellar travel would be the fuel. We couldn't bring along enough fuel to make it to even the closest star, even if the engines were 100% efficient and we used anti-matter. Which means that the fuel would have to be collected/manufactured along the way.

Bussard Ramjet.

 

[newjerseyrunner]

Bussard Ramjet.

Unlikely, the density of the interstellar medium is now known to be considerably less than it was assumed to be when Bussard made his proposal. It may work for other species in denser parts of the galaxy, but not here.

 

[Sei]

Unlikely, the density of the interstellar medium is now known to be considerably less than it was assumed to be when Bussard made his proposal. It may work for other species in denser parts of the galaxy, but not here.

Maybe a fuel-out ramjet "stops" to scoop more hydrogen and retry it? Don't forget the ramjet is moving, not stopping. I think there's a way to do.

 

[rootone]

The problem though is that the density in much of the galaxy is so low that the 'scoop' would need to be enormous to collect a useful amount of material, about the size of Earth.
Not only does that present a very major problem in constructing it, but also because of the huge volume there is more chance of a few substantial bits of rock etc being encountered, despite the overall low density, and that is not good when moving at a very high velocity.

 

[|Glitch|]

The problem though is that the density in much of the galaxy is so low that the 'scoop' would need to be enormous to collect a useful amount of material, about the size of Earth.
Not only does that present a very major problem in constructing it, but also because of the huge volume there is more chance of a few substantial bits of rock etc being encountered, despite the overall low density, and that is not good when moving at a very high velocity.

Consider also that by the time a spacecraft leaves the solar system it will already be moving at relativistic speeds. The extremely rarefied interstellar hydrogen would become more abundant the closer one approaches the speed of light.

 

[enorbet]

Back in the late 50s or early 60s G. Harry Stine, a scientist who worked at White Sands and whom was also a SciFi writer under a "nom de plume", published an article that I saw in one of the "Astonishing Science Fiction" sorts of periodicals. He made graphs with Time as the X coordinate and speed achieved by humans on the Y-axis. He did this for energy at the disposal of a single human and several other Y variations and all of them became asymptotic shortly after the year 2000. Obviously the basic premise of the exercise was flawed, that it was indeed possible for such a rate of increase to continue.

Certainly ther major component as mentioned earlier in this thread is money but that is tightly coupled to resources as well as the will of where to employ it. The very fact that it took a major fight in the US Senate to countermand the abandonment of a project as important as "the next Hubble", the James Webb Space Telescope, should give us all a clue to how willing the public seems to be to spend bucks on anything not Earthbound and of rather immediately recognizable value, assuming we can call our bloated Defense Budget as "immediately valuable".

The fact remains that even the death of our Sun in 5 billion years does not necessarily require leaving our Solar System and though it hurts me deeply, I must conclude that interstellar travel is an exceedingly long way off, given we even survive that long as a (dominant) species. Could we do it? Maybe. Will we? Sheerest optimistic speculation.

 

[Chronos]

Unless we figure out a workaround to the speed of light, space is simply too vast for interstallar travel. The demands are so enormous even antimatter would be a laughable excuse for an energy source.

 

[enorbet]

It really should be obvious that as unimaginably difficult as even near light speed would be to attain, it is woefully matched against the vast distances in interstellar travel. Anyone who doubts this has likely not seen this sobering graphic http://www.planetary.org/blogs/emily-lakdawall/2012/3390.html

It should also, in light of that pitiful achievment at full C, be obvious that the only way even remotely possible for practical interstellar "travel" is to somehow, assuming it is even possible, to fold spacetime and effectively negate the distance.

 

[newjerseyrunner]

Unless we figure out a workaround to the speed of light, space is simply too vast for interstallar travel. The demands are so enormous even antimatter would be a laughable excuse for an energy source.

I'm sorry, but I find this too anthropocentric. It's easy for me to imagine a species that has members that enjoys long bouts of solitude and lives for tens of thousands of years with the aid of medical technology. It's only laughable to you because you only live long enough for one trip, scale your lifespan up so that the fifty years it takes to get to Alpha Centauri is like taking a two week vacation.

 

[enorbet]

@newjerseyrunner - While I'm quite sure Chronos can, and likely will, respond for himself I felt compelled to interject. I am a champion of thinking outside the box but I do hope you realize just how far outside your example is. Since we know that for the most part things are pretty much like they are here the Laws that govern biology have to be stretched really far since in our experience the most complex lifeforms capable of such lifespans are on the level of yeast. Yet you imagine they are so complex they also have near light speed propulsion. The concept of a race that lives for even thousands of years asks a lot of serious questions not the least of which is reproduction and overcrowding just to name a few.

I think it is far more likely since at the turn of the century a vaguely mathematically possible spacetime-bending warp drive has at least been seriously conceived this will be the means for any civilization to achieve Interstellar "travel". Still it would seem the energy required to achieve such a broad and powerful effect is a very long way off, at best... for any manner of civilization.

 

[DrStupid]

biology have to be stretched really far

or to be abandoned

 

[newjerseyrunner]

@newjerseyrunner - While I'm quite sure Chronos can, and likely will, respond for himself I felt compelled to interject. I am a champion of thinking outside the box but I do hope you realize just how far outside your example is. Since we know that for the most part things are pretty much like they are here the Laws that govern biology have to be stretched really far since in our experience the most complex lifeforms capable of such lifespans are on the level of yeast. Yet you imagine they are so complex they also have near light speed propulsion. The concept of a race that lives for even thousands of years asks a lot of serious questions not the least of which is reproduction and overcrowding just to name a few.

I think it is far more likely since at the turn of the century a vaguely mathematically possible spacetime-bending warp drive has at least been seriously conceived this will be the means for any civilization to achieve Interstellar "travel". Still it would seem the energy required to achieve such a broad and powerful effect is a very long way off, at best... for any manner of civilization.

I would assume that a species would use it's knowledge of medicine to slowly increase it's own lifespan, slowly replace body parts with more durable machinery, and eventually abandon biology completely. I think our species will be able to do that in less than a thousand years, let alone a million.

 

[Cadar]

"Delusional fantasy" might be a bit strong, but yes, it looks as though interstellar travel by any means we can envisage based on current understanding of physics and the complexities involved tends to suggest that it belongs in the realm of science fiction. At least for now. KSR - one of the best writers in the field in my personal opinion - has this to say on the subject as a whole, not just because of the propulsion issue, but also because of the human, biological and other factors.

http://www.scientificamerican.com/article/what-will-it-take-for-humans-to-colonize-the-milky-way1/

Simply put, barring some new form of FTL propulsion we haven't discovered yet (gravity drive, anyone?), we're going to be stuck in this solar system for the foreseeable future. Which is probably for the best, considering the utter catastrophe we've made of planet Earth.

 

[anorlunda]

It's easy for me to imagine a species that has members that enjoys long bouts of solitude and lives for tens of thousands of years with the aid of medical technology.

Unless you assume FTL, then you better change "thousands" to "millions".

If we are want to presume FTL just on the principle that human achievement knows no limit, then we might as well imagine a "star trek" beam-me-up transporter that could beam remote planets, and even remote galaxies to our doorstep.

Dreams of space westerns depend on a very narrow range of visions of future technology; good enough for FTL ships, but not good enough to make such ships unnecessary.

 

[Drakkith]

I would assume that a species would use it's knowledge of medicine to slowly increase it's own lifespan, slowly replace body parts with more durable machinery, and eventually abandon biology completely. I think our species will be able to do that in less than a thousand years, let alone a million.

I imagine that we'll find ways to improve our own bodies without completely replacing them with machines.

 

[russ_watters]

Unless we figure out a workaround to the speed of light, space is simply too vast for interstallar travel. The demands are so enormous even antimatter would be a laughable excuse for an energy source.

Even worse, we're a long, long way from the speed of light being a limiting factor in our space travel. The fastest spaceships we can muster today can travel at around 0.01% of the speed of light. Even if we can somehow find the technology to increase spaceship speed by a factor of a thousand, Relativity will still be irrelevant. We're somewhere between hundreds of years and never away from being able to come even that close.

 

[marcus]

...I agree that there are monumental challenges that we may never overcome. It also seems more likely that our machines (rather than humans themselves) will be the first visitors to other star systems. Especially given the current direction of exploration in our own Solar System - we've sent our machines to the outer reaches, rather than going ourselves.
...

If our machines ever reach a comparatively nearby exoplanet, and it turns out to be a nice place, then it might be possible to send frozen zygotes there accompanied by robotics able to provide the necessary environment: do the nursing, parenting, and socialization.

A zygote is a single cell, a fertilized ovum, the first stage of an embryo. I wonder how long a zygote can last, frozen, and still develop properly when retrieved from storage. 100 years? A thousand years?

If exploratory machines can get somewhere and still function reliably once they arrive, I see nothing in principle that would prevent their establishing a colony of humans---perhaps colonies including other species of plants and animals as well.

Sending an "Ark" of live humans seems like the wrong idea: expensive, bulky, complicated, prone to failure.
One has to count on AI and robotics having reached a level where it can transmit our culture and foster recognizable fully human individuals, bridging the long gap when things are in storage during transit.

I imagine this could be tried as an experiment at shorter distances, namely in the solar system. Let the robots build the habitat and prepare for a colony somewhere---then hatch some stored "eggs" and raise the humans to populate it.

Shielding from cosmic rays seems more feasible in this picture, the biology one is sending is very compact.

 

[Drakkith]

I imagine this could be tried as an experiment at shorter distances, namely in the solar system. Let the robots build the habitat and prepare for a colony somewhere---then hatch some stored "eggs" and raise the humans to populate it.

That presents one hell of a moral dilemma...

 

[nikkkom]

Fair comment, but well established physics will still be the same.
At present it's incomprehensible what kind of engine could accelerate a fairly massive ship to a substantial fraction of light speed,
but it's not impossible in principle.

Why do you need a substantial fraction of C? If that can't be done, traveling at "only", say, 15000km/s, gets you to another star in some 100 years - not really too long a time. Well established physics has nothing against accelerating macroscopic objects to 15000km/s.

 

[nikkkom]

It's easy for me to imagine a species that has members that enjoys long bouts of solitude

You don't need to be alone on the trip. Ship can be big enough and the crew can be large enough. There are millions, if not billions of people who lived their entire life within some few square kilometers of land and interacted with less than a thousand different people.

 

[rootone]

... 15000km/s, gets you to another star in some 100 years - not really too long a time...

100 (or a few hundred) years would get us to the very nearest stars using present technology, but there are not very many of those close neighbours.
The chances of star in our immediate neighbourhood harbouring a habitable planet are extremely remote.

 

[nikkkom]

100 (or a few hundred) years would get us to the very nearest stars using present technology, but there are not very many of those close neighbours.

We don't have to go to 47 Tucanae in one giant jump. After we reach nearby stars, we can launch further expeditions from *them*.

The chances of star in our immediate neighbourhood harbouring a habitable planet are extremely remote.

Why would you want to live on a planet, that deep potential well? Asteroids are so much better. More accessible, more abundant, and more varied wrt resources. Presumably, asteroids exist around almost every star.

 

[rootone]

Yes there probably are asteroids with useful resources around most stars.
I imagine though, that establishing a variety of heavy industries entirely in space would take a very long time.
I guess your idea is workable in principle though, but in practice what would be the motivation for a project that could take well over 1000 years in total to get humans to a star system that actually might be habitable.
(or have other some other high value of interest)

 

[nikkkom]

Yes there probably are asteroids with useful resources around most stars.
I imagine though, that establishing a variety of heavy industries entirely in space would take a very long time.

Yes.
However, I think having heavy industry in space is a prerequisite for our civilization to efficiently colonize Solar System.

 

[Drakkith]

Here's a question. Are there any kinds of "launching" devices that could provide an initial burst of acceleration instead of having to rely solely on the ship's engines? Something like a very, very large electromagnetic "catapult" similar to the ones proposed for facilitating launches from Earth.

 

[rootone]

Probably doable from an engineering point of view, but to be useful (in terms of noticeably reducing overall journey time) that initial acceleration would need to be huge,
Could a human passenger survive that?, experiencing something like 50G?

 

[Drakkith]

Probably doable from an engineering point of view, but to be useful (in terms of noticeably reducing overall journey time) that initial acceleration would need to be huge,
Could a human passenger survive that?, experiencing something like 50G?

Why would the acceleration need to be so large? If we're talking about building spaceships large enough with enough fuel to accelerate to and from a significant fraction of c, I imagine that building a very long accelerator wouldn't be beyond our capability. But I haven't ran the numbers on any of that.

 

[newjerseyrunner]

Here's a question. Are there any kinds of "launching" devices that could provide an initial burst of acceleration instead of having to rely solely on the ship's engines? Something like a very, very large electromagnetic "catapult" similar to the ones proposed for facilitating launches from Earth.

Like a light sail? It'd have minimal G forces, but be able to reach relativistic speeds. Remember though, that launching isn't the only place where acceleration is needed (unless you just plan on doing a flyby.)

 

[nikkkom]

Why would the acceleration need to be so large?

Let's see.
With assisted 1g acceleration for 3600 seconds, you'd get 36 km/s and the accelerating track structure needs to be 64800 kilometers long (somewhat smaller than Jupiter radius).
At 2g, you get 72 km/s and track length is also x2 - 129600 km.
At 2g and 1800 seconds, you get 36 km/s and track length is smaller: 32400 km.
At 10g and 1200 seconds, you get 120 km/s and track length is 72000 km.

Higher G's are useful, but require your ship to be sturdier (--> heavier).
In any case, attained velocities are too low, you still would need to accelerate much more than that using your ship's propulsion.

[edit] For reference: accelerating for longer time quickly makes the track unwieldy long: 1g for one day requires a track 37 million kilometers long while giving you "only" 864 km/s.