Debunking Interstellar Travel: Separating Fact from Fiction

[mheslep]

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 ...

If the state-of-the-art amounts to no more than a raft made from sticks and palm fronds, suitable for crossing a large river at most, then yes stay at home and keep improving for another 100 generations. Crossing the 10 mile wide bay is dangerous in such craft, crossing the ocean is impossible. If crossing the ocean is 4000 times harder than crossing a mile wide river, then a 10 light year manned journey is 300 million times harder than going to the moon.

 

[mfb]

If the state-of-the-art amounts to no more than a raft made from sticks and palm fronds, suitable for crossing a large river at most, then yes stay at home and keep improving for another 100 generations. Crossing the 10 mile wide bay is dangerous in such craft, crossing the ocean is impossible.

It is impossible until someone does it.

Difficulty does not scale linearly with distance.

 

[mheslep]

It is impossible until someone does it.

Difficulty does not scale linearly with distance.

Well the pre Columbian's that might have built a Kon Tiki like sail powered craft were, what, 20,000 years out of Africa and river crossing rafts.

Granted distance dies not scale linearly with difficulty, though they are correlated, and distance provides a shorthand for showing that interstellar travel is not a few times harder than going to the moon but many orders of magnitude harder.

 

[phinds]

Well the pre Columbian's that might have built a Kon Tiki like sail powered craft were, what, 20,000 years out of Africa and river crossing rafts.

Granted distance dies not scale linearly with difficulty, though they are correlated, and distance provides a shorthand for showing that interstellar travel is not a few times harder than going to the moon but many orders of magnitude harder.

I agree. I think the leap from our Solar system to interstellar is likely to be more of an exponential change than a linear one.

 

[sophiecentaur]

I cannot claim to have read all the posts in this thread (144!) but I feel I have to comment on the limited way in which the 'enthusiasts' seem to look at the problem. The technology is only a small part of this problem. More important are the phyiology and psychology of humans. Whatever speed of travel we can postulate, we are talking in terms of timescales involving many human generations. That would take us as far into the future as prehistoric Man is in the past and what earth-bound organisation is likely to spend what would be virtually their total resources on such an uncertain investment? How could we predict how the passengers of such craft would feel and would they still want to continue on a mission on which they find themselves through no choice of theirs.
Then, what would be the motivation for such a project? Governments, these days do not get involved in projects with timescales more than one or two periods of office. There is no motivation, afaic. I cannot see the attraction of sending human 'spores' out in different directions, in the hope that even one of the many 'expeditions' could reach a suitable destination. Who would benefit from such an exercise? The genes of some humans other than myself? Where's the profit in that? Jam today vs someone else's jam tomorrow.
I admit that discussions about exotic technologies are fascinating but the Star Wars / Star trek / Dan Dare meets the Wild West and Kontiki scenarios are just fanciful.
If and when Earth gets threatened by some imminent and inescapable disaster, the place we would be going would be along the lines of Mad Max and a very sad decline until the remnants all expire. That's the way humans work and we need to accept that - but we won't.

 

[Rubidium_71]

Crossing the 10 mile wide bay is dangerous in such craft, crossing the ocean is impossible.

The thing about humans is, they actually like to take on what is dangerous. Humans also like to defy what is considered impossible.
I still don't think it is out of the question that a Generation Ship (or a ship of some other type) might someday make such a perilous journey to another star. Dangerous? Absolutely. Impossible? Not necessarily.

 

[phinds]

The thing about humans is, they actually like to take on what is dangerous. Humans also like to defy what is considered impossible.
I still don't think it is out of the question that a Generation Ship (or a ship of some other type) might someday make such a perilous journey to another star. Dangerous? Absolutely. Impossible? Not necessarily.

But you are talking about some thing that is significantly different that "dangerous". Yes, it IS dangerous but more importantly it is boring and for the immediate crew, personally pointless. Altruism is all well and good but I mean really? Dedicating your whole life so that someone ELSE can someday land on another planet while you spend your in a relatively small spaceship? Do NOT sign me up.

 

[nikkkom]

How could we predict how the passengers of such craft would feel and would they still want to continue on a mission on which they find themselves through no choice of theirs.

Well, you are on a "spaceship" Earth. You were brought into it without anyone consulting you whether you want it or not. The situation is similar. How do you, a passenger of this "craft", feel? The situation is: most people don't care about how you or I feel about it. If we feel okay, we live here, likely have children and thus the "crew" reproduces. Whoever feels miserable, can kill hiumself (or more likely, continue to feel miserable for years on end).

Then, what would be the motivation for such a project? Governments, these days do not get involved in projects with timescales more than one or two periods of office. There is no motivation, afaic.

It was hardly different at any other time in human history. Columbus had hard time raising cash for a 1-2 years exploratory trip.

I cannot see the attraction of sending human 'spores' out in different directions, in the hope that even one of the many 'expeditions' could reach a suitable destination. Who would benefit from such an exercise? The genes of some humans other than myself?

Exactly. That's the reason of existence of any lifeform: to spread (minimally: to survive). Lifeforms which don't do that, die out - the ultimate form of failure.

 

[mheslep]

The thing about humans is, they actually like to take on what is dangerous. Humans also like to defy what is considered impossible...

Sure. A manned mission to the moon was, is, dangerous. Interstellar travel with today's technology and physics is like jumping off a cliff with a garbage bag as a parachute. My guess is interstellar travel remains jumping-off-a-cliff out of reach for the next century even with on trend, incremental but non-revolutionary improvements in technology. Currently (i.e. through 2200) an interstellar project is not simply dangerous but pathological, as the Sci American article labels such projects.

With some revolutionary discoveries in physics, tech, and human civilization, who knows.

 

[mfb]

The technology is only a small part of this problem. More important are the phyiology and psychology of humans.

They are not separate problems. The technology chosen influences everything alive on the spacecraft . Concerning the lack of choice, see nikkkom: We don't have the choice today either. Launching such a spacecraft would give some humans a choice: stay on Earth, or travel into the huge interstellar void. Some concepts reach ~10% the speed of life, sufficient to get to the closest stars within a human lifetime, even with today's life expectancy. Improvements in medicine could significantly extend the human lifespan, improvements in spacecraft designs could increase the speed.

The genes of some humans other than myself?

It is still 99.95% your genes.

Governments, these days do not get involved in projects with timescales more than one or two periods of office.

ISS, ITER, LHC, the global investments in photovoltaics, a few agreements on reducing CO2 emissions, ... it happens.

That's the way humans work and we need to accept that - but we won't.

We (as species) survived an ice age and the Toba volcano with primitive tools. We can do so much more with today's technology, and even more with future technology.

 

[newjerseyrunner]

I think the biggest problem with the whole "we have to save the species" idea is that I bet most of us simply don't care. Extinction is a natural thing and if humanity were on it's way out I'd probably rather accept it and enjoy my own life than worry about whether or not there even will be a next generation. For almost all of human history we've depended on a stable climate. We've known now for a generation that we're destroying that. As a whole, the species doesn't care.

 

[mfb]

Extinction is a natural thing

So is working on not going extinct. Extinction only happens if the species cannot save itself (or gets saved with the help of other species, as we do it today in some cases).

 

[nikkkom]

I think the biggest problem with the whole "we have to save the species" idea is that I bet most of us simply don't care. Extinction is a natural thing and if humanity were on it's way out I'd probably rather accept it and enjoy my own life than worry about whether or not there even will be a next generation. For almost all of human history we've depended on a stable climate. We've known now for a generation that we're destroying that. As a whole, the species doesn't care.

The survival doesn't happen on the scale of "the species as a whole".
Only those *individuals* who have children are participating in the survival (and evolution). Every single one of your ancestors had children. Only they "succeeded" as forms of life. Not *all* humans who lived before us.

Those who enjoyed their own lives and decided to not have trouble of raising children are irrelevant now, regardless of whatever arguments they may have raised as a rationale. They are dead. Their children do not exist.

And merely having children is not the end. A tribe can have lots of children, but fail to expand out of a small valley it lives in. A small valley which happens to sit nearly a dormant volcano, for example.

For "success as a life form", it makes sense to do more than just multiply in an existing niche.

 

[sophiecentaur]

I think the biggest problem with the whole "we have to save the species" idea is that I bet most of us simply don't care.

I totally agree. A project such as being proposed would demand every member of the human race to 'go without' for generations, just so that a small number of them (or their foetuses ) could be sent on a one way trip with never any feedback about success or failure. We cannot even get the influential majority of the Earth's population to take the subject of Climate repair seriously. Of course, they deny climate change because that keeps the status quo, with unchanged lifestyles for the wealthy (within their limited forward vision). There is no motivation to prevent looming local disaster, so why would attitudes change so that this Noah's Ark project could be funded?
The attitude of humans is to 'save me, my immediate family and possibly some more distant friends and relatives'. That is the same attitude that early tribal mankind evolved with. The difference is that we no longer live in tribes of a few dozen.
I cannot understand how the people who are excited by the possible technologies involved with such a project (me too, in many respects) seem to ignore the way that human nature works. There is no, even remotely, similar project in our history. It is not the slightest bit like crossing the Oceans in tiny boats or riding West on a wagon train. The Earth is small enough for a human to have traveled around it at least once in their lifetime and this has been true for centuries or even millennia. Going home has never been 'impossible' like it would be for this venture.
There are alternative strategies to prolong the life of humanity that are much more realistic - but they do not have the appeal of this grand idea. The same thing applies to schemes for terraforming our neighbours in the solar system. How could anyone possibly think that it could be done successfully when there is no inclination to look after the place that we evolved on?

 

[sophiecentaur]

The survival doesn't happen on the scale of "the species as a whole".

But the survival, in this case, would demand the involvement of 'the species as a whole'.
Who cares enough?

 

[phinds]

For "success as a life form", it makes sense to do more than just multiply in an existing niche.

Which does not in any way address the issue I brought up in post #147

 

[anorlunda]

Regarding @sophiecentaur 's point in #145. I can visualize the following conversation.

Astronaut : Here I am, back to report success of the generation mission to Kepler 134.
Politician : What the f* are you talking about?
Astronaut : You know. The generation star mission you launched 150,000 years ago to preserve the human species. Reporting back was a requirement for accountability of the money spent.
Politician : No I don't know. What's a human? What's a money?

 

[sophiecentaur]

Regarding @sophiecentaur 's point in #145. I can visualize the following conversation.

Astronaut : Here I am, back to report success of the generation mission to Kepler 134.
Politician : What the f* are you talking about?
Astronaut : You know. The generation star mission you launched 150,000 years ago to preserve the human species. Reporting back was a requirement for accountability of the money spent.
Politician : No I don't know. What's a human? What's a money?

I love it.
There is the inverse square law and there is the inverse relevance law of space distances.

 

[nikkkom]

But the survival, in this case, would demand the involvement of 'the species as a whole'.

Not necessarily. A sufficiently big part would do.

While some part of humanity mount a mission to Mars, and later, to Jovian moons, and then KBOs, and then Proxima, some other parts of humanity can still sit on a small peninsula (or small asteroid), half-starving, brainwashed by their tribe leader into thinking that everyone wants to kill them, and it's vitally important for them to put all efforts into having not 2, but 3 nuclear devices (instead of a mission to far away new worlds).

 

[CalcNerd]

With the very real prospect of never ever actually finding another Earth (even it one should actually exist) and the ever increasing abilities of gene modification, mankind will likely have to consider unmanned robotic missions with AI. These missions (done on the cheap with low cost especially in comparison with generational or hibernation technologies) would send out spacecraft with robotic systems that could terraform new planets that had possibilities for life (terraforming with genetically modified bacteria/algae, whatever..). The process could take millennia. Then genetically modify some humanoid that could survive on the resulting rock and move onto the next system. The time scale would be in tens of thousands to millions of years, but to a robot AI with a mission to populate as best as possible, mankind (in some genetically altered state best suited for each planet capable of life) could flourish.
.
I cannot imagine any other solution for space travel, unless there is some unforeseen space propulsion system discovered and developed. All current technologies, even when achieving theoretical perfection fall short due to energy requirements, fuel mass, and life support systems for any practical system.

 

[sophiecentaur]

I said
"But the survival, in this case, would demand the involvement of 'the species as a whole'."

Not necessarily. A sufficiently big part would do.

A sufficiently big part would impose the cost on all the others - so same thing. We still 'owe' the majority of the world a good (acceptable) living. We all know that those at the bottom of the pile would 'pay' for such a massive project - even thought it may not be admitted.

 

[phinds]

All current technologies, even when achieving theoretical perfection fall short due to energy requirements, fuel mass, and life support systems for any practical system.

Not JUST current technologies but any foreseeable extrapolations of those technologies. That's what the optimists keep overlooking (or are unwilling to accept). "Thinking out side the box" in this case seems to require getting so far outside the box that it is just nonsensical.

 

[nikkkom]

With the very real prospect of never ever actually finding another Earth (even it one should actually exist) and the ever increasing abilities of gene modification, mankind will likely have to consider unmanned robotic missions with AI. These missions (done on the cheap with low cost especially in comparison with generational or hibernation technologies) would send out spacecraft with robotic systems that could terraform new planets that had possibilities for life (terraforming with genetically modified bacteria/algae, whatever..). The process could take millennia. Then genetically modify some humanoid that could survive on the resulting rock and move onto the next system.

In 100-500 years, we run rather high chances of being partially or even completely "cyborgized". For one, today's prosthetic hands, legs, ... lungs... hearts... think where this road ends.

Spending millennia changing planets to be suitable for a particular kind of ape to live does not look smart. Changing the ape is faster.

I cannot imagine any other solution for space travel, unless there is some unforeseen space propulsion system discovered and developed. All current technologies, even when achieving theoretical perfection fall short due to energy requirements, fuel mass, and life support systems for any practical system.

Not really. This was raised in this thread already: 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.

 

[rootone]

... 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.

That's still 3 or 4 generations to get to the nearest star, and the alternative of 'hibernating' the crew is science fiction at present.
Consider also that the chances of an Earth-like planet existing at a star system which is one of the Suns close neighbours is very low.
Earth like planets may well exist within the scope of say 100ly, but to get to those the number of generations looks more like 50.

 

[mfb]

Dedicating your whole life so that someone ELSE can someday land on another planet while you spend your in a relatively small spaceship? Do NOT sign me up.

Don't worry, other people will sign up.

Only those *individuals* who have children are participating in the survival (and evolution).

What about a brother/sister helping the other one and their children? Thinking of species as a single tree is too easy. Every individual has some impact on the survival and reproduction of others.
In addition, genes are not the only thing we pass on - our ideas, values and so on are passed on as well, and they don't need a direct genetic link.

A project such as being proposed would demand every member of the human race to 'go without' for generations

Huh? Citation needed.

with never any feedback about success or failure

A 40-year trip to Proxima Centauri would certainly allow feedback.

It is not the slightest bit like crossing the Oceans in tiny boats or riding West on a wagon train. The Earth is small enough for a human to have traveled around it at least once in their lifetime and this has been true for centuries or even millennia. Going home has never been 'impossible' like it would be for this venture.

Some ocean crossings were one-way streets. The people never came back. And still some people went along this one-way street - without even knowing if there was a target to land! We are in a much better position - we can study the possible destinations from Earth.

How could anyone possibly think that it could be done successfully when there is no inclination to look after the place that we evolved on?

Our planet would look much worse if there would be no inclination to look after it. There is. In addition, it is mainly a political problem. You would not have this political problem on places like Mars: You would not have to explain anyone that the climate outside is not optimal for humans.

With the very real prospect of never ever actually finding another Earth (even it one should actually exist)

Wait, what? Kepler showed that Earth-sized planets in habitable zones are common, and it just looked at a tiny fraction of the sky, and only for transit-planets which is a tiny subset of all planets. TESS and PLATO should find some 4-digit number of them. JWST and E-ELT can do spectroscopy for the closest planets, so we can study their atmospheric composition. This is not science fiction, those are telescopes that will take data within 2-10 years.

I cannot imagine any other solution for space travel, unless there is some unforeseen space propulsion system discovered and developed. All current technologies, even when achieving theoretical perfection fall short due to energy requirements, fuel mass, and life support systems for any practical system.

Nuclear propulsion. There was a concept study for an interstellar spacecraft for 10% the yearly US GNP. Roughly the money the US spends on its military per year, and a nearly irrelevant number as global project.

Consider also that the chances of an Earth-like planet existing at a star system which is one of the Suns close neighbours is very low.

Depends on what you count as Earth-like. Roughly the mass of Earth, about the same amount of radiation? Then the nearest planet is at the same distance as the nearest star, because Proxima Centauri has such a planet.

 

[sophiecentaur]

Huh? Citation needed.

Do we really need specific citations for government spending affecting the fortunes of the poor? India receives international Aid on the grounds of its poor population but can afford vanity projects in Space. And it is by no means the only example.

 

[sophiecentaur]

Some ocean crossings were one-way streets. The people never came back. And still some people went along this one-way street - without even knowing if there was a target to land! We are in a much better position - we can study the possible destinations from Earth.

Of course there were many fatalities in ancient exploration but the timescale for a successful trip would have been well within a lifetime. Most exploration involved island hopping.
A significant proportion of astronauts fail to return too. (A very dangerous occupation by modern standards). There is no parallel here with multi-generational voyages. Alpha Centuri is not representative of the sort of trip that would be involved.

 

[rootone]

Depends on what you count as Earth-like. Roughly the mass of Earth, about the same amount of radiation? Then the nearest planet is at the same distance as the nearest star, because Proxima Centauri has such a planet.

I guess I mean a planet that could be habitable.
A planet on which it could be possible to at least place an enclosed and durable artificial habitat on the surface.
Essential commodities like water and some minerals, (metals?), being accesible

We have Venus in the solar system which is similar to Earth in terms of mass and radiation, but placing a habitat on the surface is a non-runner.

 

[nikkkom]

That's still 3 or 4 generations to get to the nearest star

...Which is not impossible. That's my point.

Consider also that the chances of an Earth-like planet existing at a star system which is one of the Suns close neighbours is very low.

Even the Proxima's planet can have regions suitable for humans to live, this possibility is not ruled out.

Earth like planets may well exist within the scope of say 100ly, but to get to those the number of generations looks more like 50.

Having 50 generations on a ship is not impossible. The poster I replied to thinks it's impossible, and he "cannot imagine any other solution for space travel" but a robotic terraformer with genetic seeds. Something makes him think people can't be born and raised on a ship. ?!

 

[sophiecentaur]

I really don't see the motivation for this project. A very few - either mature or foetal - 'colonists' would be involved. It could never be a rescue exercise for all of us. So why would the huge majority want to spend money on such an exercise? Exploration in the past was always based on economic factors. Ships were financed by a backer, expecting a return on their money. What return would you and I expect, for our 'investment' (hardly the right word)? Nothing would be worth bringing back to Earth.
Some of those left behind might experience a rosy glow about the whole thing. A pretty expensive ego trip.
I guess that there could be scientific data from such an expedition but even that would be bad value as it would involve the extra expenses involved with human cargo.

 

[mfb]

Do we really need specific citations for government spending affecting the fortunes of the poor? India receives international Aid on the grounds of its poor population but can afford vanity projects in Space. And it is by no means the only example.

No, I am interested in a reference showing that any project of interstellar travel would need huge efforts by generations of humans on Earth ("A project such as being proposed would demand every member of the human race to 'go without' for generations"). Especially as we have studies like Project Orion with cost estimates that are fundable within 10 years of 1% of the US GNP.

Alpha Centuri is not representative of the sort of trip that would be involved.

Alpha Centauri is a different star. A journey to Alpha Centauri would be interstellar travel. And it is reachable within a human lifetime with current (!) technology (although the price would go up for this sped-up trip).

A planet on which it could be possible to at least place an enclosed and durable artificial habitat on the surface.
Essential commodities like water and some minerals, (metals?), being accesible

That is even better than the habitable zone. Mars and various moons and asteroids would fit within our solar system alone.

It could never be a rescue exercise for all of us.

Neither was Columbus trip. See what happened later.

Exploration in the past was always based on economic factors.

What was the economic factor of going to the North/South pole? To the top of Mount Everest or the bottom of the Mariana trench? To the moon? What is the immediate direct economic factor of fundamental science? At least for now, humans can do science much more efficiently than robots. If robots can do science better than we can, then they can do nearly everything better and our society will change more than ever before anyway.

 

[rootone]

That is even better than the habitable zone. Mars and various moons and asteroids would fit within our solar system alone.

Then it would be a good idea to go with putting self sustaining colonies on those first before thinking of settlements in other solar systems.
(if the motivation is to have an established base of human habitation other than Earth)

 

[mfb]

Then it would be a good idea to go with putting self sustaining colonies on those first before thinking of settlements in other solar systems.
(if the motivation is to have an established base of human habitation other than Earth)

I don't think anyone wants to start interstellar missions before we got humans to Mars (to stay there) and at least research bases at a few other destinations in the solar system.

 

[mheslep]

...If and when Earth gets threatened by some imminent and inescapable disaster, the place we would be going would be along the lines of Mad Max and a very sad decline until the remnants all expire...

We have a good idea from history what happens after calamities. There's a mix of behaviors, but there's plenty of evidence that in the face of calamity human behavior most often follows the opposite of the 'Mad Max' theme. People quickly reach out to join small groups for support, become more adaptive, more social. Social divisions in place prior to the calamity fade in importance. There are also of course negative behaviors that manifest in the mix as well, but in most cases the positive wins out over the negative.

That's the way humans work and we need to accept that - but we won't.

Yes I grant that the apocalypse (Mad Max, Zombies, Rapture May 2011) has a house of horrors fascination to many, but the dogmatic, contrary to all evidence assertions that everyone must accept these predictions of the future as fact; that I find bizarre.

See e.g. http://wsnet.colostate.edu/CWIS584/Lori_Peek/Data/Sites/1/1-research/publicationpdfs/zahranetal2009.pdf

...Many studies of post disaster deviance and antisocial behavior draw on Fritz’s (1961) concept of the therapeutic community to explain why rates of crime decline (or increase only modestly) after a disaster event. Fritz (1961) argues that post disaster behavior is adaptive, prosocial, and aimed at promoting the safety of others and restoration of community life. Many reasons account for post disaster altruism and other community oriented behaviors. First, social divisions tend to dissolve in the aftermath of a disaster. Risk, loss, and suffering become public rather than private phenomena (Fritz 1961, p. 685). This relative equality of suffering promotes solidarity among disaster victims and sympathizers.1 Second, human survival needs are widespread and visible in the aftermath of a disaster (Fritz 1961, p. 684). Visible suffering increases empathy, inducing social cooperation to solve immediate problems like rescue and debris clearance. Third, natural disasters enable groups to introduce desired reforms into a social system (Fritz 1961, p. 685). For social entrepreneurs, disasters represent opportunities for social change.
...
According to Fischer (1998), looting is the most expected criminal response to a natural disaster. Logically, opportunities for widespread theft are said to increase following a disaster because private property is unprotected. Contrary to logical expectations, scholars find that incidences of looting in the aftermath of a disaster are empirically rare...

 

[Vanadium 50]

Interstellar travel with today's technology and physics is like jumping off a cliff with a garbage bag as a parachute.

Or maybe a sketch of a garbage bag as a parachute.