Space travel and the future of humanity

SuprSi

I hope it's ok to post this in here as it's quite OT but I figured it would be the best place to get proper answers to a question that has been bugging me of late.

I watched Pandorum last night. In case you haven't seen it, it's a futuristic sci-fi 'Event Horizon' sort of thing. It's not a great movie, but the idea behind it is that Earth, in 200 years, becomes a place with too many people and not enough resources - not too unrealistic a plot. Anyway, deep space travel and hypersleep have been invented, and they find a planet like Earth that the human race can move to.

So, this got me thinking, with the recent cancellation of the space shuttle by the US and, despite probes being sent into outer space, and with Earth's resources constantly on the decline, what will happen to the human race in the future? I'm not talking a few hundred years, but beyond that. Space exploration seems seriously off the cards for the US, especially considering their debt - can the other space nations move things on in their absense?

Eventually, unless something massive happens, there will be too many people to be sustained on this planet. Also, (and I'm aware of the distances between planets and galaxies and the length of time it would take to get there) where would we get the resources required to fuel a vessel that could travel to another planet or galaxy, if this was even an option? Obviously it's not something we'll hvae to directly worry about but I'm curious to know if you have any opinions.

Zubeneschamali

I think:

Human space travel into the Solar system will probably happen for science and exploration, but there is nowhere to live out there that's anything like as hospitable as the nastiest place on Earth, so there won't be any colonization.

Population will level off before 2050. Shipping people into space will never be a useful way to relieve population pressure.

Human interstellar travel is completely impractical, and always will be.

seamus

SuprSi wrote: »

Eventually, unless something massive happens, there will be too many people to be sustained on this planet.

That may not be so. Although we don't like to think so, our species is under the influence of natural forces as much as any other. There are plenty of other species which are arguably as successful as humans, and yet they don't manage to breed themselves into a corner.
I think it's unlikely that we will grow our population beyond a point where we can feed ourselves. Wars, famines and education will eventually take care of it.

I also don't accept the contention that human interstellar travel is completely impractical and always will be. Over the last few hundred years it has been stated countless times by high-level academics that science was on the verge of running out of steam because we had learned everything there is to learn. IMO it's always premature to declare something a permanent impossibility.
However, it's not something we'll ever see in our lifetimes, and likely our children will see nothing of it. At best, we may see the initial spark of it - some great discovery which unlocks more potential which we hadn't known before.

Though if/when it ever does happen, it might be nothing like we currently imagine of great vessels moving between stars in real-time. We could end up slaves to relativity anyway, sending crews on long voyages of ten or twenty years (from their perspective) at near the speed of light, to return to earth 100 years hence (or however it would work).

namloc1980

Zubeneschamali wrote: »

I think:

Human space travel into the Solar system will probably happen for science and exploration, but there is nowhere to live out there that's anything like as hospitable as the nastiest place on Earth, so there won't be any colonization.

Population will level off before 2050. Shipping people into space will never be a useful way to relieve population pressure.

Human interstellar travel is completely impractical, and always will be.

I don't think it's that clear cut to be honest. I do believe that Mars will be colonised by humans in the future. There is plenty of frozen water on Mars so you have the basic ingredients to support a human colony as it is possible to extract oxygen from the water and also you can create fuel (hydrogen and oxygen) from water. Obviously there are many technological hurdles to be overcome so that colonists could live successfully on Mars, but I see no reason why it couldn't happen eventually.

2 stroke

When we do find a planet or moon which is ideal for human life, we should expect to find it already occupied.

BULLER

2 stroke wrote: »

When we do find a planet or moon which is ideal for human life, we should expect to find it already occupied.

Not necessarily by intelligent life though

I do believe its only a matter of time before we colonise Mars. It's not beyond even our current technology by any means!

AlmightyCushion

BULLER wrote: »

Not necessarily by intelligent life though

I do believe its only a matter of time before we colonise Mars. It's not beyond even our current technology by any means!

For a colony to be truely successful it would need to be self sufficient and sustainable. We could get to mars if we threw enough cash at the mission but a colony that didn't need constant supplies from earth is still some way off.

BULLER

AlmightyCushion wrote: »

For a colony to be truely successful it would need to be self sufficient and sustainable. We could get to mars if we threw enough cash at the mission but a colony that didn't need constant supplies from earth is still some way off.

I believe it's very possible to "live off the land" of Mars today. How is it way off? Hydrogen brought from Earth is the very lightest element and only supply they would really need! It can be reacted with CO2 in the Martian atmosphere to produce The hydrogen brought from Earth can be quickly reacted with the Martian atmosphere, which is 95% carbon dioxide gas (CO2), to produce methane and water. Methane for fuel and water for drinking. Nuclear reactors could also be brought. I'm sure they'd find sources of Hydrogen on Mars with some actual exploring. It is afterall, the most abundant element!

"Mars is already known to possess a vital resource that could someday represent a commercial export. Deuterium, the heavy isotope of hydrogen currently valued at $10,000 per kilogram, is five times more common on Mars than it is on Earth."

Robert Zubrin's Mars Direct was spot on in so many ways; "Travel light and live off the land"

Rhys Essien

A manned mission to Mars WILL happen in the next 30/40 years.The Americans and Russians both have stated this.
Shur havent the Russians in the last few months done their 'practice' mission.

namloc1980

AlmightyCushion wrote: »

For a colony to be truely successful it would need to be self sufficient and sustainable. We could get to mars if we threw enough cash at the mission but a colony that didn't need constant supplies from earth is still some way off.

There is plenty of vital ingredients on Mars to make a colony self-sufficient primarily ice which will provide water for drinking and for growing food, oxygen for breathing can be extracted from water as can Hydrogen for fuel. All of these things can be done with current technologies. Initially a colony would require support from Earth but eventually it could become essentially self-sufficient with some ongoing support.

The key to colonising Mars successfully would be that for the people going there it would be a one-way journey and there would be no option to return to Earth.

AugustusMinimus

We may not have the technologies needed for colonization of Mars today, but I have no doubt that with very focused objectives and enough money, these technologies can be developed over a short enough time scale.

Zubeneschamali

AugustusMinimus wrote: »

I have no doubt that with very focused objectives and enough money, these technologies can be developed over a short enough time scale.

Sure, but Antarctica, or the Himalayan plateau, or the middle of the Sahara Desert, are all more hospitable places to live. No-one's ever going to go to Mars because it's a nice place to live.

And when people need to work in an inhospitable place, we already know how that looks. Folks don't move families to Antarctic science stations or North Sea oil rigs.

So yes, a science station may someday be established on Mars, but no-one is ever going to colonize it.

Similarly, we could have a 2001 style space station in orbit of Earth, but it will always be a high radiation, high risk environment. No sane person will try and raise kids up there.

BULLER

It's no antartica though...its a different planet. The frontier of discovery! Adventure of traveling through space millions of miles. Not to mention the 37% gravity, would be nice to be able to do 200 pressups and almost be able to fly! I dont think you'd have a shortage of people who'd want to go to be honest! Your arguements a bit flawed in that sense. You'd be hardpressed to find people to live in the poles on earth!
Without a doubt we will one day colonise the solar system, its embedded in our very nature. It's only a matter of when, not if!

namloc1980

Zubeneschamali wrote: »

Sure, but Antarctica, or the Himalayan plateau, or the middle of the Sahara Desert, are all more hospitable places to live. No-one's ever going to go to Mars because it's a nice place to live.

And when people need to work in an inhospitable place, we already know how that looks. Folks don't move families to Antarctic science stations or North Sea oil rigs.

So yes, a science station may someday be established on Mars, but no-one is ever going to colonize it.

Similarly, we could have a 2001 style space station in orbit of Earth, but it will always be a high radiation, high risk environment. No sane person will try and raise kids up there.

People live and have lived for thousands of years in the Sahara and Tibetan Plateau. Future technological advances will mean Mars will be colonized eventually. To say it will never happen is to ignore human history of exploration and colonization. Children will be born and raised on Mars and for them Earth will be a hostile alien world and Mars will be home.

Enkidu

I don't think interstellar travel will ever be possible since you can't go faster than light. As for inside the solar system, it's hard to know. Weather systems are among the most chaotic phenomena in nature, so terraforming would be a science requiring possibly impossibly advanced computational abilities, so I'm not sure if terraforming is a realistic idea or just a cool sci-fi fictional device.

I would imagine colonies could be established on Mars and some moons, but they'd be inside biodomes or habitats. I think it would be interesting to imagine what kind of society would develop there, since any screw up in maintenance would result in everybody's death.

Spacedog

the destiny of the human race will end in 1 of 2 ways...

1) We all eventually die on this planet, be it by blowing our selves up, or by an eventual catastrophic event.

2) we find a way to transfer human life to other worlds using any means possible. be it through suspended sleep, travel, or by transmitting our genetic material and knowledge into the depths of space. who is to say that our origin is not from a canister of bacteria launched into space by some strange aliens?

anyway, either we get out and live for ever or die off.

Manach

I rather like the concept of a massive Dyson sphere URL="http://en.wikipedia.org/wiki/Dyson_sphere"]link[/URL myself.

slade_x

Enkidu wrote: »

I don't think interstellar travel will ever be possible since you can't go faster than light. As for inside the solar system, it's hard to know.

The person saying something will never be possible could very well be contradicted by another person achieving that very thing at that time. And if history tells us anything after a few years are nearly always proven wrong. The limit you can accelerate a mass to doesnt have to limit our ability for interstellar travel as if or when we achieve it, chances are it will be some form of dilation of space time

Enkidu wrote: »

Weather systems are among the most chaotic phenomena in nature, so terraforming would be a science requiring possibly impossibly advanced computational abilities, so I'm not sure if terraforming is a realistic idea or just a cool sci-fi fictional device.

As an example our current level of computational ability would be completely unfathomable 40 years ago, Apollo 11's guidance computer was a pre x86 1 mhz processor with 2kb of memory

Modern pocket/ scientific calculators have a clock rate of upwards of 6 mhz. If anyone has any knowledge of modern computers they'd know how ridiculous it is to make a comparison.
In modern computing the megahertz race is long over with computers operating on levels so vastly different than how they did even just 10 years ago

We have proven we can change the climate of this planet alone and we werent even trying. Who's to say eventually we wont be able to do it if we put our minds to it

Enkidu wrote: »

I would imagine colonies could be established on Mars and some moons, but they'd be inside biodomes or habitats. I think it would be interesting to imagine what kind of society would develop there, since any screw up in maintenance would result in everybody's death.

You can bet it would be a much bigger venture than the ISS when we eventually inhabit other planets. The current death toll for inhabitants on the ISS is at present zero.

No one knows what our future holds and no one will ever know what we are or are not capable of in our ultimate future, and thats a fact.

bombs away

Plenty of theories at the moment on ways to get around the light speed barrier, theories admittedly but if history has thought us anything, where there's a will

Kidchameleon

I a couple of billion years, as the sun gets hotter, Mars and Titan will be warmer and much more hospitable. I don't believe any colonization will happen any time soon, but it probably will happen way way into the future. Who would have thought even 70 years ago that a man would have walked on the moon?

AugustusMinimus

Enkidu wrote: »

I don't think interstellar travel will ever be possible since you can't go faster than light. As for inside the solar system, it's hard to know. Weather systems are among the most chaotic phenomena in nature, so terraforming would be a science requiring possibly impossibly advanced computational abilities, so I'm not sure if terraforming is a realistic idea or just a cool sci-fi fictional device.

Our nearest star, Proxima Centauri is just over 4 lights years from earth.

That would be a journey of 40 years if we got a spaceship up to 10% of the speed of light. Give enough time, this might be quite possible actually.

irishh_bob

SuprSi wrote: »

I hope it's ok to post this in here as it's quite OT but I figured it would be the best place to get proper answers to a question that has been bugging me of late.

I watched Pandorum last night. In case you haven't seen it, it's a futuristic sci-fi 'Event Horizon' sort of thing. It's not a great movie, but the idea behind it is that Earth, in 200 years, becomes a place with too many people and not enough resources - not too unrealistic a plot. Anyway, deep space travel and hypersleep have been invented, and they find a planet like Earth that the human race can move to.

So, this got me thinking, with the recent cancellation of the space shuttle by the US and, despite probes being sent into outer space, and with Earth's resources constantly on the decline, what will happen to the human race in the future? I'm not talking a few hundred years, but beyond that. Space exploration seems seriously off the cards for the US, especially considering their debt - can the other space nations move things on in their absense?

Eventually, unless something massive happens, there will be too many people to be sustained on this planet. Also, (and I'm aware of the distances between planets and galaxies and the length of time it would take to get there) where would we get the resources required to fuel a vessel that could travel to another planet or galaxy, if this was even an option? Obviously it's not something we'll hvae to directly worry about but I'm curious to know if you have any opinions.

due to the fact that man has made such huge strides in terms of science and technology this past hundred years ( moon landing etc) and hollywoods potrayal of colonisation of other worlds occuring some time in the next two hundred years , a lot of people have come to the conclusion that we will be living on other plannets within a few short centurys , the reality is probabley much different , read an article by some space expert recently who took a more realistic view

we will at best land a man on mars by the year 2100
in order to make mars habitable for large numbers of people , citys etc , the planet will have to be terrafirmed , this will take several centurys , realistically thier could be colonys on mars by the year 3000 , this is on the planet closest to us , a thousand years is a relativley short period of time in human history , combine this fact with the gargantuan distances involved in travelling to other planets with the limits on life expectancy and you have a huge number of odds stacked against mankind , travelling beyond the solar system would involve generation ships where generations of people would live and die while travelling to instestellar space , the technology needed to achieve this requires a near reinvention of the wheel in terms of a great leap forward , it could be thousands and thousands of years before we are living on plannents akin to the movie avatar which was laughably set in the year 2154 , 3154 would be far fetched

namloc1980

irishh_bob wrote: »

we will at best land a man on mars by the year 2100

I don't share your pessimism on this. We could land men on Mars within a decade if the resources were put into achieving that goal. Look at what was achieved with Apollo using 1960s technology when NASA were pretty much given a blank cheque. I'd like to think that the first man or woman on Mars has already been born.

irishh_bob

namloc1980 wrote: »

I don't share your pessimism on this. We could land men on Mars within a decade if the resources were put into achieving that goal. Look at what was achieved with Apollo using 1960s technology when NASA were pretty much given a blank cheque. I'd like to think that the first man or woman on Mars has already been born.

i should have included a link to that article i read but i cant find it

im 34 , i seriously doubt i will live to see reports of a mars landing

namloc1980

irishh_bob wrote: »

i should have included a link to that article i read but i cant find it

im 34 , i seriously doubt i will live to see reports of a mars landing

There are no insurmountable technical issues to sending humans to Mars. NASA have been successfully landing unmanned spacecraft on Mars since the 1970's. The primary barriers are financial and political.

BULLER

irishh_bob wrote: »

im 34 , i seriously doubt i will live to see reports of a mars landing

I bet you 1000 euro you will!

AugustusMinimus

irishh_bob wrote: »

i should have included a link to that article i read but i cant find it

im 34 , i seriously doubt i will live to see reports of a mars landing

I would also take that 1000 Euro bet.

I would take it that

1. You will see a manned landing on Mars within the next 40 years
2. Due to massive advances in medical science, life expectancies will increase dramatically over the next 50 years. As it stands, the increase in life expectancy in the West each year is actually accelerating. It will get to the point within 50 years where the increase each year will be greater than a year.


Another fact is that the USA after Apollo could have put a man on Mars around 1980. Getting them back was the major problem.

irishh_bob

namloc1980 wrote: »

There are no insurmountable technical issues to sending humans to Mars. NASA have been successfully landing unmanned spacecraft on Mars since the 1970's. The primary barriers are financial and political.

im not disagreeing with that , just saying , im 34 , i doubt man will land on mars in the next 50 years or so

irishh_bob

AugustusMinimus wrote: »

I would also take that 1000 Euro bet.

I would take it that

1. You will see a manned landing on Mars within the next 40 years
2. Due to massive advances in medical science, life expectancies will increase dramatically over the next 50 years. As it stands, the increase in life expectancy in the West each year is actually accelerating. It will get to the point within 50 years where the increase each year will be greater than a year.


Another fact is that the USA after Apollo could have put a man on Mars around 1980. Getting them back was the major problem.

you think life expectancy will increase dramatically , define dramatically , average of 90 , present average for a man is around 78 afaik , who knows , the average life expectancy could be 150 some day but i imagine that would take at least a thousand years , medical science can prolong a persons life but keeping someone alive untill they are 125 is not the same as someone being able to pilot a spacecraft on thier 135th birthday

Norrin Radd

These links outline a century by century future timeline of humanity.

Very good stuff and quite relevant to this thread..

http://zibzib.sandwich.net/setting/doku.php?id=history:21stcentury:timeline

http://zibzib.sandwich.net/setting/doku.php?id=history:22ndcentury:timeline

http://zibzib.sandwich.net/setting/doku.php?id=history:23rdcentury:timeline

AugustusMinimus

irishh_bob wrote: »

you think life expectancy will increase dramatically , define dramatically , average of 90 , present average for a man is around 78 afaik , who knows , the average life expectancy could be 150 some day but i imagine that would take at least a thousand years , medical science can prolong a persons life but keeping someone alive untill they are 125 is not the same as someone being able to pilot a spacecraft on thier 135th birthday

A lot of scientists estimate that the first person to reach 200 will have been born in the 1960s.

Wibbs

irishh_bob wrote: »

you think life expectancy will increase dramatically , define dramatically , average of 90 , present average for a man is around 78 afaik , who knows , the average life expectancy could be 150 some day but i imagine that would take at least a thousand years , medical science can prolong a persons life but keeping someone alive untill they are 125 is not the same as someone being able to pilot a spacecraft on thier 135th birthday

Maybe not. Mortality is an engineering problem albeit a very complex one at the moment, but we're gaining insight on a yearly basis. In 1000 years I would be utterly gobsmacked if humans or whatever passes for human then weren't functionally "immortal". If theorists are right and a singularity is reached whereby artificial intelligence equals and then surpasses the human mind(and then you'll have exponential growth) that will happen significantly more quickly. It's possible people alive today may be alive in 200 years time. If you live long enough, you may well live long enough to live for a very very long time indeed.

Then you have the machine intelligences themselves(though I use the word "machine" very loosely). If you look at the evolutionary history of humanity, we stand alone among animals in that we drove our progress by external evolution. We didn't rely on physical evolution alone. We started as an omnivorous, though mostly vegetarian ape. Meat was a great source of calories and nutrients, but we didn't have the claws and speed to catch it, the to sharp teeth to cut it up, nor the strong stomach acid to digest it. We didn't wait around. We made tools and mastered cooking instead. I'd take this even further going forward. Pretty much all species die out. The vast majority die out leaving no descendant species. If we were like other animals the same would be true of us. But we're not. We may evolve outside of dumb evolution our own descendant species. Humanities children. The "artificial" intelligences. The tools of our own future as it were. They/we may grow together, they may leave us behind, but they'll be human. In the way that we may be a magnitude more advanced than Homo Erectus, but they were human and they live on in us.

Such humans I dunno Homo Sapiens Machina would be far more capable than we can even imagine. they may even prefer space as the cold might suit their "bodies". Time would no longer be an issue. Travel to another star? Leave, go into sleep mode until you arrive. No generation ships required.

Then there's star travel itself. Is it possible? I'm not talking about lack of faster than light stuff stopping us or others out there if they exist in any number. It may be more simple than that. OK I've read about dark matter and how it seems to make up the majority of stuff in the universe. Maybe we don't need some exotic matter to explain it(or a lot of it). Maybe outside of stable solar systems space is very cluttered. Not empty at all*. That teh Oort cloud keeps going and going until it reaches another solar system. That the higher energy environments around stars shovels up all the matter into chunks like planets and keeps the space between relatively clear and navigable and beyond that while gravity is the same the engine of a star is not driving it and material is very diffuse? An analogy might be a harbour in the polar regions. Ships moving about the harbour keep the ice to a minimum and speed boats can fly along with no great risk of head butting an iceberg, but beyond the harbour a ship has to move much more slowly. So even if we could reach near light speed there's just too much stuff to hit to make interstellar travel possible?

Of course there's another human trajectory where we become internalised, living in fully immersive virtual worlds that reality can't hope to match so we bother less and less with actual reality and traveling. The global species equivalent of the guy watching porn and playing with himself while the reality of his girlfriend upstairs sleeps alone. Maybe intelligent species nearly always do this? Maybe only being outward thinking for 10,000 years and that's why we don't see them?

The major thing about looking to the future is we always miss something. Something relatively "meh" today or not around yet that turns out to be hugely important in a fresh new way. In the 60's we thought we;d be fartin about n Mars by now. And we had good reason to think so. Computers were huge yokes and telephone lines were for chatting. Now today the Americans can't even lob a man into space on their own anymore and I'm writing this on a computer talking to ye over a phone line. I've no doubt this will happen again, maybe even more in the future.



*it would be still quite empty. We're not talking sci fi asteriod belts here, but full enough compared to interplanetary space.

Wibbs

AugustusMinimus wrote: »

A lot of scientists estimate that the first person to reach 200 will have been born in the 1960s.

Yep and if they reach 200, then the tech will be running with them and they may see 3, 4 5 600. I doubt it'll be me. I've rolled one too many bad lifestyle dice. :mad::) Then again we may discover that we can make near immortal humans, but only from birth, not if they're already alive, merely extend those ones lives but to a much more finite point. If it does happen I can see longevity wars kicking off. It's gonna be a major resource that likely only a few societies will have at first.

The most worrying possibility is a return to a dark ages of sorts, or luddite wars.

AugustusMinimus

Wibbs wrote: »

Yep and if they reach 200, then the tech will be running with them and they may see 3, 4 5 600. I doubt it'll be me. I've rolled one too many bad lifestyle dice. :mad::) Then again we may discover that we can make near immortal humans, but only from birth, not if they're already alive, merely extend those ones lives but to a much more finite point. If it does happen I can see longevity wars kicking off. It's gonna be a major resource that likely only a few societies will have at first.

The most worrying possibility is a return to a dark ages of sorts, or luddite wars.

3 advancements will lenghten lifespan over the next 50 years in the following order.

1. Further advancements in general Medicine.
2. Genetic revolution
3. Nanotechnology.

Unless we do see a return to the dark ages, longevity is about to go crazy.

Enkidu

slade_x wrote: »

The person saying something will never be possible could very well be contradicted by another person achieving that very thing at that time. And if history tells us anything after a few years are nearly always proven wrong. The limit you can accelerate a mass to doesnt have to limit our ability for interstellar travel as if or when we achieve it, chances are it will be some form of dilation of space time

Possibly I'm just sceptical, but I don't see it being possible. Faster-than-light travel is explicitly forbidden by relativity, even worse according to relativity the concept doesn't make any sense. As for dilating space-time, again General Relativity and the behaviour of matter precludes such things. It's fine and well to say that things may be possible but here we have explicit "no-go" results from physics itself.

We have proven we can change the climate of this planet alone and we werent even trying. Who's to say eventually we wont be able to do it if we put our minds to it

Changing the climate is not enough. Smashing glass is not the same as being capable of glass sculpting. The problem with controlling the climate is that the computational limits are independent of the computers they are run on. Since climate systems are chaotic the algorithms themselves grow quicker than exponentially in the size of their input, which is independent of the hardware they're run on.
Also any realistic advance in science requires working out bugs and kinks, and something as complex as terraforming will have a lot of bugs and kinks, more than anything we've attempted to date by orders of magnitude. This will require a large sample size on which to run and re-run the technology. Remember that a single sample point is a planet and one "run" could take decades, then you could be looking at tens of thousands of years of development.

No one knows what our future holds and no one will ever know what we are or are not capable of in our ultimate future, and thats a fact.

True, but I think healthy scepticism is a good idea, science doesn't always lead to our most optimistic hopes.

Enkidu

AugustusMinimus wrote: »

Our nearest star, Proxima Centauri is just over 4 lights years from earth.

That would be a journey of 40 years if we got a spaceship up to 10% of the speed of light. Give enough time, this might be quite possible actually.

At 10% of the speed of light a collision with a pebble would release enough energy to rip the earth's crust off the mantle. Collision with even a speck of dust would be like hitting the ship with a Hiroshima bomb. Magnetic shielding would be useless as a lot of the debris would be neutral.

Enkidu

AugustusMinimus wrote: »

3 advancements will lenghten lifespan over the next 50 years in the following order.

1. Further advancements in general Medicine.
2. Genetic revolution
3. Nanotechnology.

Unless we do see a return to the dark ages, longevity is about to go crazy.

I'm probably being a real downer here:D, but my problem with this stuff is aside from a few very vocal scientists and transhumanists like Ray Kurzweli, a lot of scientists seem to consider this stuff quite unlikely. Particularly any talk I've been to about nano-technology has emphasised that it's not at all "like the movies", basically being custom molecular engineering (with strong limits) and not robots manipulating atoms.

Enkidu

Wibbs wrote: »

OK I've read about dark matter and how it seems to make up the majority of stuff in the universe. Maybe we don't need some exotic matter to explain it(or a lot of it). Maybe outside of stable solar systems space is very cluttered. Not empty at all*. That teh Oort cloud keeps going and going until it reaches another solar system. That the higher energy environments around stars shovels up all the matter into chunks like planets and keeps the space between relatively clear and navigable and beyond that while gravity is the same the engine of a star is not driving it and material is very diffuse?

I think observational evidence rules out such a scenario. If there was a good bit of interstellar debris outside the solar system we'd see it in some range of the electromagnetic spectrum.

tricky D

It's a fascinating problem. Here's my 2 cent.

A long term colony on Mars is out for the simple reason of 37% gravity. It would be a great practice platform.

If we are to 'start over' somewhere else, there's a list of essential ingredients that we are going to need for the destination planet, something like:

• similar gravity g+/-10%
• water
• right temperature range
• life of some sort
• close-matching atmosphere which implies a magnetosphere for shielding from harmful cosmic rays and atmosphere retention
• probably a moon for tides, I think this is an crucial factor in life evolving here
• We might be able to get away with rotation significantly varying from 24hrs.
• I wouldn't be too confident on terraforming: it would take a long long time and with the variables would be too easy to get wrong with only Mars available for practice, if even.
• anything else?

FTL is in the realm of fiction and magic wands and even something like wormholes would probably need so much energy (bits of stars) that they would be impossible. We have never seen any evidence that we know of for them. Nevermind the problems like how to stop at the other end, wherever/whenever that is.

As for getting there, these kinds of matters would be in play:

• finding somewhere suitable. This might mean checking out quite a few star systems for suitable planets
• which means loads of fuel... more than we have on Earth and likely the Moon
• travelling within a solar system and between ones will probably need different propulsion/fueling systems: some thing like a carry-on initially, then collect in later mission phases. Maybe Hydrogen3-based system for within, and a pick up the one Hydrogen per cubic metre between systems using a massive 'scoop' hundreds of not thousands of miles in diameter for beyond solar systems for both propulsion and storage. This would be dangerous to use in solar systems due to debris. I read somewhere pre the Web days about such a system being able to accelerate, handily enough, at around g (important that), which gets turned around midway to decelerate. This means a trip time to our closest neighbours of very roughly 50-70 years. That's tens of thousands of years on Earth due to relativity so we're pretty much not coming back.
• Best to aim at a bunch of likely suspect stars, as opposed to single stars, as we might have to make a few hops until the sufficient ingredients are found. And/or we might need to change course on the way as we eliminate unsuitable destinations as we scan ahead. Changing course wouldn't be easy.
• Then there's who and what do you bring: what raw materials? Full society level crew (thousands/tens of thousands) or pilot crew (hundreds) with human cargo in suspension/long sleep or in vitro [Edit] with a pilot crew maintained mainly as female (contentious).

As for the matter of our overpopulation on Earth, Mother Nature will eventually get the little things sort that out through disease and the like. That or our next evolved state will push us out. [I've been watching too many X-Men films this week;)]

slade_x

Enkidu wrote: »

Possibly I'm just sceptical, but I don't see it being possible. Faster-than-light travel is explicitly forbidden by relativity, even worse according to relativity the concept doesn't make any sense. As for dilating space-time, again General Relativity and the behaviour of matter precludes such things. It's fine and well to say that things may be possible but here we have explicit "no-go" results from physics itself.
.

I never said actual faster than light travel was possible. and general relativity does not preclude dilating space time. it actually predicts the existance of black holes and other phenomena that warp space time. We dont have to accelerate mass past the speed of light to make an interstellar trip.

The reality of what we can do is only limited by our current understanding of physics which is obviously limited. We may understand or be able to predict a lot of interactions but we in know way know the true secrets of our universe and possibly beyond. We do not yet have all the pieces of the puzzle, we cant even expect to know what will be possible if or when we do

Wibbs

Enkidu wrote: »

I think observational evidence rules out such a scenario. If there was a good bit of interstellar debris outside the solar system we'd see it in some range of the electromagnetic spectrum.

Not necessarily E, the Kuiper belt was only discovered in the early 90's and the extent of which is still up for grabs and the Oort cloud is still largely a hypothesis albeit a good one based on observations as they stand. They're both a start point for debris and with every passing month/year we're seeing more and more (V large)objects even at that great distance. The notion that the belt/cloud keeps on going is not so fanciful. Observation of extra solar deep space? OK one point, how do we know the luminosity of the stars we see is their actual luminosity? Unless we park a probe within such star systems to measure same in the locale we just can't know for sure. There may well be lots of crap in the distance between us augmenting their light.

Leidenfrost

The short term future of Space travel and Humanity is that we will begin Mining asteroids for raw materials in this century, but only once it becomes economical to do so.
Raw materials like Rhodium, Platinum, and other platinum group elements and not to mention rare earth elements are more than plentiful in the Asteroid Belt, and with Earth's resources being stretched, the prices that these metals demand will continue to rise, there will come a point when it is economical to deorbit 2 to 3 metre diameter metal rich meteoroids/asteroids, them coming to rest in the Sahara or Australian desert.

How to make mass human space travel profitable:
http://www.amazon.com/Mining-Sky-Untold-Asteroids-Planets/dp/0201328194

A video discussion on 'Mining the sky' and making Space travel uber profitable
http://www.youtube.com/watch?v=XLt6yv-rNhI

We should all realize Space travel will never ramp up until there is a reason to go, it is not the massive Launch costs that is holding us back, that's a myth. Once there is a reason to go it will get a whole lot cheaper. The reason why is because there will once again be launch vehicle/'rocket' assembly lines- as there was in the case of the V-2 rocket, Ever since then, rockets have been ''made to order'' and as you can imagine costs will never come down if that stays the status quo, the costs to low earth orbit LEO in $/kg has yet to go below $1000 per kilogram.

I am hopeful that endeavours like Burt Rutan's sub orbital Spaceshiptwo will open space up to the average person, but then again Vomit Comet flights have been fixed at $10,000 for years. And it is only a niche market, as is a flight in a Mig-29 Fulcrum roughly E10,000
http://www.incredible-adventures.com/dreams.html
A Hard choice...but the Mig 29 flight seems a better deal.
Tourism just might get the ball rolling, who knows.

Short of Myrabo style lightcraft or building giant Space elevators, the mass production of launch vehicles is our only realistic option.
Here's an intro into Myrabo lightcraft, notice the reaction mass is air.
http://www.youtube.com/watch?v=-Nm16wp0kMs

The other driving force that could be behind a future ramp up in Space travel would be, much to your chagrin, military exploitation of space. Unfortunately the Outer Space treaty is getting in the way of that.


And as for Zubrin & Mars, Yes we should go to Mars and put a scientific outpost there, but why would we want to stay there? what tourists will want to deal with the global sand/dust storms that Mars is famous for?
Mars holds nothing much more than scientific interest, Scientists should land and a lab should be set up, and unless something amazing is found, it will be the end of Mars story. Someone here mentioned Deuterium mining on Mars? Ask yourself this, why would you go all the way to bleeding Mars for Deuterium fuel!?! it would be far, far, far cheaper to keep extracting it from sea water right here on Earth.

Instead of Mars settlements It would be a much more logical step to start building small Stanford Torus' and O'Neill Cylinder space stations in low earth orbit, Lagrangian points like L5 and in the asteroid belt-where Mining will be a big industry.
An example of the potential of Stanford Torus space stations and their eventual use for interstellar missions>
http://www.youtube.com/watch?v=oazFe2jbMxw

As for propulsion methods for interstellar missions, requiring a cruise speed of at least around 0.5 c (50% of the speed of light) LASER beamed power and antimatter catalyzed nuclear pulse propulsion hold the most promise.
If you doubt that high speed, need I remind you that with 1950s technology we could have built a craft capable of 5-10% of the speed of Light the 'Project Orion' Nuclear pulse propulsion system.

This Covers Project Orion, Forward's LASER beamed propulsion, & possibly dubious Bussard ramjets.
http://www.nasa.gov/centers/glenn/technology/warp/ideaknow.html
A brief report on LASER Propulsion
http://www.niac.usra.edu/files/studies/final_report/4Landis.pdf

As for the radiation hazard from long term stays in space. Well the major danger for Interstellar travel will be GCR galactic cosmic rays, luckily with only a few centimeters of Polythene plastic the hazard is diminished to an acceptable level for interPlanetary travel.**

This discusses RFX1 a polythene based shielding material, lighter but more effective than Aluminium
http://science.nasa.gov/science-news/science-at-nasa/2005/25aug_plasticspaceships/

Lead shielding is actually more trouble than a help see 'Bremsstrahlung radiation' for confirmation of this.

Once you realize that with the power available from an onboard power source such as a Fusion reactor*, you can imagine it won't be too long before physicists and engineers create a magnetic & electrostatic field strong enough around a manned vehicle to mimic the effects of earth's magnetosphere, which would further reduce the number of galactic cosmic rays reaching the crew. So a vehicle utilizing all 3 shields- modest thickness Polythene shielding, Magnetic & electrostatic fields - that's the Radiation hazard pretty much licked.
Of Course there are other possibilities, like using Asteroid material as Shielding and so on, but we'll leave asteroid shielding for a Space Station discussion.

*As for onboard power for deep space missions, well that will be supplied by Tokamaks, Fusion power plants akin to the Reactor currently being built in France, the ITER. Fusion power has already surpassed the break even point, or Q=1 just look up the JT-60 reactor that pretty much demonstrated it.
Here's an intro to ITER
http://www.youtube.com/watch?v=_MoPydT_Zrg&feature=related

** I was Not taking into account that the energy in eV of the Galactic cosmic rays colliding with the vehicle will be, in effect, increased by the speed of the vehicle. i.e the energy of the colliding cosmic particles and the vehicles speed are directly proportional. Naturally this effect will only be a problem when the vehicle has a velocity greater than 10% of the speed of light, such a vehicle will require an onboard reactor and therefore the creation of a large magnetic and electrostatic field will be possible, such fields can together adequately diminish the hazard from relativistic cosmic rays and as I previously discussed, radiation in general.

Possibly the single best paper on the Hazards from relativistic(close to light speed) travel and the engineering solutions.
http://cdsweb.cern.ch/record/988025/files/0610030.pdf
A good powerpoint that Discusses various Magnetic Shielding methods.
http://engineering.dartmouth.edu/~simon_g_shepherd/research/Shielding/docs/ToMaSS.pdf

So for Mitigating the hazards of close to the speed of light travel:
1.The Front of the craft should thus house a generator for the creation of a Large magnetic field( since a Tokamak generates an enormous magnetic field anyway this will be like killing 2 birds with 1 stone).
2.The forward section should also house a forward facing LASER to push(by radiative pressure) any neutral pieces of dust and other micro-meteoroids, out of the way of the craft.
Therefore the Interstellar medium no longer poses any potentional hazard to our vehicle, and more importantly, to our crew.

Enkidu

slade_x wrote: »

I never said actual faster than light travel was possible. and general relativity does not preclude dilating space time. it actually predicts the existance of black holes and other phenomena that warp space time. We dont have to accelerate mass past the speed of light to make an interstellar trip.

True, but General Relativity only allows one way to do that, a lot of Mass-Energy, an amount equivalent to a few suns, which realistically humans will not be able to manipulate, where would they get it.
The only feasible way to travel would be in sleeper or generation ships moving very slowly and by slowly I mean less than a hundredth of the speed of light.

slade_x wrote: »

The reality of what we can do is only limited by our current understanding of physics which is obviously limited. We may understand or be able to predict a lot of interactions but we in know way know the true secrets of our universe and possibly beyond. We do not yet have all the pieces of the puzzle, we cant even expect to know what will be possible if or when we do

Fair enough, but the reality might be even more restrictive than what current physics allows, it's 50/50. The unknown is just that unknown, however currently available science (which let's be clear explains virtually every particle interaction in the universe as well as the broad features of the universe from now back to its birth) indicates that these things will not be possible. In fact we already have evidence that things get more restrictive. General Relativity on its own allows time machines, but add in quantum mechanics and they're gone.

Leidenfrost

Enkidu wrote: »

At 10% of the speed of light a collision with a pebble would release enough energy to rip the earth's crust off the mantle. Collision with even a speck of dust would be like hitting the ship with a Hiroshima bomb. Magnetic shielding would be useless as a lot of the debris would be neutral.

Firstly, there aren't, relatively, very many pebbles out there in the interstellar medium, and the majority that are out there will charged and thus deflected by magnetic & electrostatic Shielding (Galactic cosmic rays which comprise mostly of positive Protons and of high Z atomic mass positive ions - like Fe 56 tend to staticly charge objects they collide with) and for the very few that will be completely neutral- I can deal with them spherical bastards!
A relatively low energy LASER will push them out of the way.
Ever see a comet tail? The same mechanism will be employed, its all done by Radiation pressure.
There will be 'headlights' on the front of the interstellar vehicle, and these LASER headlights will push any would be collision hazards to the 'curb'.
Another problem solved, So come at me bro, I'm ready for any of your pessimism :-)

Interestingly while looking for examples of my headlights (interstellar medium plough by the radiative pressure effect- for close to light speed travel ) idea (surely I must have read about it in a NASA paper or something?), I found the below site that is pop sciency but states that science fiction has never dealt with the problem of the impact hazard for interstellar travel... So perhaps this is an original concept of mine- There is no question on whether the concept would not work, Radiation pressure is a well studied phenomenon, the only draw back I can see of the LASER light plough is that it would produce a small thrust opposite to the direction of travel , requiring more Propulsive energy to be required. But this would be a small price to pay for complete crew safety.
http://www.astronomycafe.net/qadir/q2720.html

Leidenfrost

Enkidu wrote: »

True, but General Relativity only allows one way to do that, a lot of Mass-Energy, an amount equivalent to a few suns, which realistically humans will not be able to manipulate, where would they get it.
The only feasible way to travel would be in sleeper or generation ships moving very slowly and by slowly I mean less than a hundredth of the speed of light.

you are misguided, please see my previous post on LASER propulsion, the energy source powering them will be large Solar arrays or Fusion reactors.
not to mention look up the Bussard Ramjet, which essentially does away with the need for onboard tanks of fuel.
And if the Bussard ramjet creates more drag than it's worth, then please also note that The current (2011) record for antimatter storage is just over 1000 seconds performed in the CERN facility, a monumental leap from the millisecond timescales that previously were achievable.
http://www.nature.com/nphys/journal/v7/n7/full/nphys2025.html

And it may not be possible but Black hole - Hawking radiation propulsion could be a possibilty
http://www.universetoday.com/45571/black-hole-drive-could-power-future-starships/

Enkidu wrote: »

General Relativity on its own allows time machines, but add in quantum mechanics and they're gone.

Patently incorrect, we travel into the future all the time, detectable by atomic clocks in planes and in orbit.
At 99% of the speed of light, time dilation for the crew would be such that felt journey time is 1/7th of Earth time, hence the crew will be going into the future.
So For a trip to the Alpha Centauri star system of approx 4.3 light years distant, the crew will get there and their onboard calender would appear to say it only took them 7 months.

http://www.amnh.org/learn/pd/physical_science/week3/time_dilation.html
http://www.thebigview.com/spacetime/timedilation.html

Furthermore about your doubts on Humanity wielding such massive amounts of energy(certainly not the entire energy output of the sun, let alone a few-honestly where in the world do you even get these figures?)

Check This out, we're on track to probably do an interstellar voyage in 100-200 years.
http://en.wikipedia.org/wiki/Kardashev_scale

Enkidu

Leidenfrost wrote: »

Patently incorrect, we travel into the future all the time, detectable by atomic clocks in planes and in orbit.

I'm speaking of backward time travel, as an example of how discovering more has restricted possibilities. In General Relativity backward time travel is possible in some scenarios, but add in quantum mechanics and it is gone.

Furthermore about your doubts on Humanity wielding such massive amounts of energy(certainly not the entire energy output of the sun, let alone a few-honestly where in the world do you even get these figures?)

That's the amount of mass required to dilate time gravitationally, i.e. warping space-time. You are talking about special relativity's dilation of time.

Enkidu

Wibbs wrote: »

OK one point, how do we know the luminosity of the stars we see is their actual luminosity? Unless we park a probe within such star systems to measure same in the locale we just can't know for sure. There may well be lots of crap in the distance between us augmenting their light.

I think this is handled by statistical analysis. For example take the observed output spectrum of a star and check if it matches the predicted output spectrum for an unobstructed star, then repeat for stars in certain areas of the sky to improve statistics.

Leidenfrost

Enkidu wrote: »

I'm speaking of backward time travel, as an example of how discovering more has restricted possibilities. In General Relativity backward time travel is possible in some scenarios, but add in quantum mechanics and it is gone.


That's the amount of mass required to dilate time gravitationally, i.e. warping space-time. You are talking about special relativity's dilation of time.

Not to offend but you strike me as a person who knows only Pop-sci knowledge of Quantum Mechanics and Relativity.
As for backwards time travel, Quantum mechanics has not entirely closed the Book on time travel to the past, it is extremely unlikely that we will someday be able to create a stable Wormhole, but I wouldn't call it impossible just yet.

In response to your second sentence-
firstly, Why exactly where you apparently talking about mass induced gravitational time dilation in a Space travel discussion thread?

Secondly, statements like ''That's the amount of mass required to dilate time...'' are misnomers. All Mass dilates time, and you stated 'energy' and not mass in your previous post that I was replying to.

Thirdly, General Relativity is compatible with Special Relativity in regard to Velocity induced time dilation, and more importantly it has been experimentally verified numerous times.
please look up 'Velocity time dilation tests'.
I get the sneaking feeling you are a troll...So I'm getting out of here.

3ndahalfof6

tricky D wrote: »

It's a fascinationg problem. Here's my 2 cent.

A long term colony on Mars is out for the simple reason of 37% gravity. It would be a great practice platform.


If we are to 'start over' somewhere else, there's a list of essential ingredients that we are going to need for the destination planet, something like:

• similar gravity g+/-10%
• water
• right temperature range
• life of some sort
• close-matching atmosphere which implies a magnetosphere for shielding from harmful cosmic rays and atmosphere retention
• probably a moon for tides, I think this is an crucial factor in life evolving here
• We might be able to get away with rotation significantly varying from 24hrs.
• I wouldn't be too confident on terraforming: it would take a long long time and with the variables would be too easy to get wrong with only Mars available for practice, if even.
• anything else?

FTL is in the realm of fiction and magic wands and even something like wormholes would probably need so much energy (bits of stars) that they would be impossible. We have never seen any evidence that we know of for them. Nevermind the problems like how to stop at the other end, wherever/whenever that is.


As for getting there, these kinds of matters would be in play:

• finding somewhere suitable. This might mean checking out quite a few star systems for suitable planets
• which means loads of fuel... more than we have on Earth and likely the Moon
• travelling within a solar system and between ones will probably need different propulsion/fueling systems: some thing like a carry-on initially, then collect in later mission phases. Maybe Hydrogen3-based system for within, and a pick up the one Hydrogen per cubic metre between systems using a massive 'scoop' hundreds of not thousands of miles in diameter for beyind solar systems for both propulsion and storage. This would be dangerous to use in solar systems due to debris. I read somewhere pre the Web days about such a system being able to accelerate, handily enough, at around g (important that), which gets turned around midway to decelerate. This means a trip time to our closest neighbours of very roughly 50-70 years. That's tens of thousands of years on Earth due to relativity so we're pretty much not coming back.
• Best to aim at a bunch of likely suspect stars, as opposed to single stars, as we might have to make a few hops until the sufficient ingredients are found. And/or we might need to change course on the way as we eliminate unsuitable destinations as we scan ahead. Changing course wouldn't be easy.
• Then there's who and what do you bring: what raw materials? Full society level crew (thousands/tens of thousands) or pilot crew (hundreds) with human cargo in suspension/long sleep or in vitro [Edit] with a pilot crew maintained mainly as female (contenious).

As for the matter of our overpopulation on Earth, Mother Nature will eventually get the little things sort that out through disease and the like. That or our next evolved state will push us out. [I've been watching too many X-Men films this week;)]

assuming that we want to stay exactly as we are now, adapting to our surrondings it would be easier to change than to try to stay the same.

we would be moving away from earth so no need to look for the exact same conditions, but find a new situation and adapt,

the mind can not reach to the limits required to travel in space yet, but once we have the information it will happen.

Wibbs

Leidenfrost wrote: »

Firstly, there aren't, relatively, very many pebbles out there in the interstellar medium

My contention would be we simply don't know that yet L. Kuiper belt/oort cloud are relatively recent discoveries and we simply don't know how much "stuff" is out there and we may be dealing with objects way bigger than pebbles. But let's imagine this material stops at some point and then we're into open seas between the next cloud surrounding the star we're aiming at, a ship would still have to navigate the clouds before it could really ramp up the speed. Yes like the asteroid belt the material is very diffuse but the current ideas of size of the Oort cloud means a much higher chance of slamming into one at the kind of speeds we'd need. I wonder could you even detect an oncoming one at those speeds? Or would it be like a ship at full steam charging through an icefield at night(and that didn't do Leonardo de Caprio any favours:D)

Enkidu wrote: »

I think this is handled by statistical analysis. For example take the observed output spectrum of a star and check if it matches the predicted output spectrum for an unobstructed star, then repeat for stars in certain areas of the sky to improve statistics.

Maybe but I would have thought the only star one could use as an unobstructed reference would be our own.

I'd be inclined to agree with Leidenfrost. I don't see any major barrier to near light speed in an unobstructed environment. Indeed I'd not be shocked to find that in a 1000 or 2000 years time if not much sooner we may well crack FTL travel with new insights in physics and in such a way that it doesn't hugely contradict what we know currently.

As for the energy needed, again I'm very much with Leidenfrost on this. It's nothing like the energy output of a star. I'd go even further(and I reckon he'd agree) and say I'd have no problems with a sufficiently advanced civilisation being able to control star energy levels at some point. There's nothing in our current understanding of physics that would preclude it. It's "just" an engineering problem. If that's the case then sooner or later the engineering will be possible.

IE someone like Newton could have easily imagined a trip to the moon and he built much of the physics roadmap to do so. The engineering of his time couldn't have built nor have been able to control the energy levels required to do so. Yet a couple of centuries later 12 men walked on the moon. So all this is possible, however whether we choose to do so is the thing. We know we can go to the moon, but we choose not to today. Interstellar trips may end up the same way. We may fire a probe at near light speeds to somewhere local and then stop.

Enkidu

Leidenfrost wrote: »

Not to offend but you strike me as a person who knows only Pop-sci knowledge of Quantum Mechanics and Relativity.

Well let me remove some doubt about that. In General Relativity there are a few solutions of the Field Equations which contain closed timelike curves, as well as a broad family of solutions which are not stably causal and can be made to contain closed timelike curves with only a small perturbation.
This is fine in General Relativity, of course timelike curves will mean the state of matter in the future is not just a function of it in the past (lack of global hyperbolicity), but this doesn't really matter.

However add in quantum mechanics and things change. The quantum mechanical stress-energy expectation value [latex]\left<T_{\mu\nu}\right>[/latex] can never have the properties required (when used as a source in the field equations) to produce these spacetimes.

As for backwards time travel, Quantum mechanics has not entirely closed the Book on time travel to the past, it is extremely unlikely that we will someday be able to create a stable Wormhole, but I wouldn't call it impossible just yet.

I don't think so, see:
http://projecteuclid.org/DPubS?service=UI&version=1.0&verb=Display&handle=euclid.cmp/1158328656

For wormholes see:
http://arxiv.org/abs/grqc/0510079

For lack of warp drive after the addition of quantum field theory see:
http://xxx.lanl.gov/abs/gr-qc/9702026

In response to your second sentence-
firstly, Why exactly where you apparently talking about mass induced gravitational time dilation in a Space travel discussion thread?

After the sentence "warp spacetime" was mentioned.

Secondly, statements like ''That's the amount of mass required to dilate time...'' are misnomers. All Mass dilates time, and you stated 'energy' and not mass in your previous post that I was replying to.

Okay, distort spacetime to scales significant to humans, as I obviously meant from context. Finally using energy and mass interchangeably is common in relativity, as they are the same thing.

Thirdly, General Relativity is compatible with Special Relativity in regard to Velocity induced time dilation, and more importantly it has been experimentally verified numerous times.
please look up 'Velocity time dilation tests'.

I'm aware of that, every spacetime in GR looks locally like Minkowski spacetime. I never said Lorentz transformation induced dilation didn't exist.

I get the sneaking feeling you are a troll...So I'm getting out of here.

So I have doubts about interstellar travel based on my knowledge of physics and expressing those doubts makes me a troll.