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Future gazing: The prospects for interstellar travel

Jonathan Amos | 08:30 UK time, Tuesday, 15 March 2011

I've been troubled of late by the scale of things, by the vastness of space.

It's been brought into focus by two things, I think. The first is the Voyager 1 probe - the most distant man-made object from Earth.

I've written a couple of articles recently about this veteran explorer. Launched in 1977 on a grand tour of the outer planets, it's now making a push to leave the Solar System. It's getting very close to crossing into interstellar space. Scientists know this from the way particles thrown off our star are behaving in the vicinity of the probe.

Icarus ship at Neptune

Electric propulsion could see us make more frequent, faster trips to the outer planets

Whereas this "solar wind" has always streamed past Voyager, the particles have now slowed and are moving sideways from it. In other words, Voyager has reached the point where the Sun's domain of influence is pressed right up against that of other stars.

And yet, as extraordinary as Voyager is, its efforts to reach out across space still seem quite puny. In 33 years, it has travelled 17.4 billion kilometres. That sounds a lot - and it is. But it's a tiny fraction (1/2,300) of the distance to the nearest star - Proxima Centauri.

The implications of the "sluggish performance" from this piece of 20th Century technology are underlined by the latest discoveries from Nasa's Kepler space telescope.

Kepler was launched in 2009 to identify planets by looking for the periodic, tell-tale dips in light as these objects pass in front of their host stars.

The telescope views only a small patch of sky but its findings can be extrapolated across the Milky Way Galaxy. Initial projections would indicate that within about 1,000 light-years of Earth, there may be 30,000 or more planets with potentially habitable conditions.

And here's the point that's been troubling me: if we have difficulty in reaching out to a distance equivalent to the nearest star (4.2 light-years), can we seriously ever think of getting to some of these far-flung planets?

For sure, the next generation of giant telescopes will be able to probe their atmospheres and tell us what sort of worlds they are. But what if we discover that a number of them betray tantalising evidence of biology? What then?

All this brings me to this month's edition of the British Interplanetary Society's Spaceflight magazine. The BIS has always harboured future-thinkers (Sir Arthur C Clarke among the greatest) and the magazine has often acted as their forum for discussion.

The current edition of Spaceflight runs an article from an international team of scientists and engineers - with members in the UK, the US, Germany, Australia and Hungary - who have applied themselves to just this issue.

Project Icarus, as they call their venture, have tried to envisage the ships we could be building in the decades and centuries ahead that might just get us a decent distance across space in a time which means something on a human scale.

New propulsion technologies are key, of course. The feeble chemical rocketry that sent Voyager on its way in 1977 will not do. Most favoured are the emerging electric propulsion systems.

These rely on the motion of highly excited gases, or plasmas, moulded by magnetic fields to provide thrust. Although they don't give the initial big kick you get from chemical combustion, their supreme efficiency means they can go on thrusting for extended periods, achieving far more acceleration per kilogram of fuel consumed.

A glimpse of what may be possible in the future can be seen in what appears to be the current pacesetter - a type of electric engine called Vasimr (Variable Specific Impulse Magnetoplasma Rocket).

Interstellar travel ship

"World" ships that crossed space to visit other star systems would still take centuries and would be colossal in scale

Labelled a "game changer" by Nasa, this technology is likely to be fitted to the International Space Station in the next few years to help boost its orbit, which has a tendency to decay over time as the platform skirts the top of the atmosphere.

Vasmir prototypes have already produced remarkable performance in laboratory tests. The developers, Ad Astra or Texas, believe their megawatt-class units could get a ship to Mars in as little as three months.

Project Icarus envisages bigger systems that could push deep into interstellar space in just a few decades. Nuclear fusion reactors that drive gigawatt-class vessels may eventually get robots and even humans to other star systems.

Kelvin Long, Project Icarus team-member and co-author of this month's Spaceflight magazine article, said:

"To include a crew on a mission that will take decades to centuries presents many engineering and environmental control issues. For human transport the only credible way is a generation ship or a World Ship, carrying tens to hundreds of people who will arrive at the destination and attempt to colonise one of the planets. Before they go, much about the planet will already be known, from long distance exoplanet discoveries.
  
"In terms of sending an unmanned probe, the main motivation for this is science return. Long range astronomical observations will improve over time with higher fidelity measurements, but it is difficult to compete with having an actual spacecraft in the system able to study any stars or planets close up, perhaps deploying planetary probes and landers - ultimately looking for signs of life. Along the way, the probe can also conduct valuable science such as improving astronomical parallax measurements or looking for gravity waves. The exploration of the cosmos is the main reason for launching a probe like Icarus.
 
"Ultimately, we would like to find life in the Universe and ideally intelligent life other than our own. Conducting theoretical studies like... Project Icarus is the only way we can push forward to the stage where we can eventually build something like it, and then perhaps someday go see for ourselves."

 

Comments

Page 1 of 3

  • Comment number 1.

    No mention of Project Orion?

  • Comment number 2.

    This is a very interesting conundrum. It's something that has been pushed to the back burner for decades now as more pressing things have been found to spend the billions of dollars (inevitably) on, and I can't see it attaining any focus until such time as our current efforts produce suitable candidates for further exploration.

    But, it's a fascinating subject, and anyone who's looked at a clear, star-filled sky at night can't fail to be impressed and inspired by it.

  • Comment number 3.

    When it comes to interstellar travel, I often think of Scotty form Star Trek who, apparently, said "you cannee break the laws of physics, captain!" And then pressed the warp drive button which did precicely that.

    Scientists love the far flung future - it is the unknown country that they can safely dream of without having to worry about being around to actually face it or justify it.

    I can see maybe many years from now, minor, probably robotic colonisation of our solar system as we consume and demand more resources. But I have problems envisioning a time when the pure outrageous cost of space travel drops to a level that is affordable.

    The giant space ships, almost mini planets, that would be required to travel over years and years to reach the stars are so vast that the combined GNP of the entire world would barely buy the ignition key.

    These futures are Utopian dreams, which is wonderful in itself, but still dreams.

    There is a little bit of pointless logic here. If interstellar travel is possible and can become common, and if highly intelligent life is rare, then we must be the oldest of the galaxy's intelligent peoples, for if there were ones much older and more advanced than us, we may well have heard from them - or just HEARD them as the noise from such a rich, vast and intelligent people must be deafening. But we have heard not a note.

    After all, they will have the same laws of physics as we and maybe they have also discovered, like Scotty, that the big button that says Warp Drive does rather less than he had hoped.

  • Comment number 4.

    The trouble with interstellar travel is lack of commitment, in that people can barely think past their own lives and lifetimes. If we were serious, we'd have already launched generational ships with the intention of people living and reproducing on the journey. Would you want to leave almost everyone you love behind to live and die in a metal tin without any chance of reaching your destination?

  • Comment number 5.

    Yes, Quentin, Orion was an early sketch of a nuclear-powered spacecraft. More to the point, Jonathan, is that Icarus is a successor project to the groundbreaking Daedalus study of the 1970s. Daedalus was a design study of a robotic interstellar probe capable of reaching a nearby star (Barnard's Star was chosen) in 50 years flight time, led by Alan Bond and Tony Martin. It was the first major technical study to yank starships out of the realm of fantasy and science fiction and into the realm of cool engineering calculation. Icarus is conceived as a review of Daedalus 30 years on, and an updating in the light of the latest technical knowledge.

    Although Icarus (http://www.icarusinterstellar.org/) is again conceived as a robotic probe, some of us at the same time are also thinking of revisiting the worldship concept mentioned by Kelvin Long above.

    Certainly many people find the vast scale of the Galaxy troubling - I find it mind-expanding. (The same with contemplating the depth of geological time on Earth.)

    I think the political take-home message is that the growth of the human economy and of our technological capabilities has a very long way to go. If we keep our nerve and sensibly manage the problems of development and the environment on our mother planet Earth, we could be rewarded with progress in space which seems as fantastic to us now as a 747 jumbo jet would have seemed to Columbus.

    Stephen
    Oxford

  • Comment number 6.

    It is our nature to question, to probe boundaries, but I suspect that interstellar travel will remain a dream, sad though that may be. It is my feeling that without sufficient social, political and scientific drivers, we can never invest enough treasure to make sub-light interstellar travel a reality, at least for humans. The trillions upon trillions of dollars required to research and build anything approaching a viable generation ship are just not there, and many would argue from a moral standpoint that they should never be, when our own world is so far short of anything one could describe as ideal.
    My suspicion is that any human exploration outside even just the inner solar system depends upon biology- or physics-related issues that are yet to be solved, i.e. real, working 'hypersleep', something that is perhaps achievable, or faster-than-light travel, which I'm not betting on.
    Until then, I guess we can all continue dreaming, there's no harm in that...

  • Comment number 7.

    "When it comes to interstellar travel, I often think of Scotty form Star Trek who, apparently, said "you cannee break the laws of physics, captain!" And then pressed the warp drive button which did precicely that."

    I agree your post Hastings to a certain extent. We can talk about fancy propulsion drives that increase efficiency of engines as much as we like but we will still be bound by our current understanding of physics. We cannot go faster than the speed of light. But who knows what understanding we might have of quantum mechanics in years time to bend current laws of physics. Would we be able to harness this to travel beyond our solar system?

    Until that time we, as humans or even our mechanical servants, will be limited to exploring the solar system. Cost and technological problems will make any other travel unfeasible. Sadly I think the time when we can understand quantum mechanics, much less exploit it, is at least hundreds of years away.

  • Comment number 8.

    Thank you, Stephen, for filling in some of the relevant background. I was already rambling at great length.

  • Comment number 9.

    No mention of Sagan and his Pale Blue Dot at all? Eeeeek.

  • Comment number 10.

    Without faster than light travel I can't see human exploration beyond our solar system ever occuring. The amount of resources required to build a world ship would probably take 10's or 100's of times all the resources so far used in space exploration combined. The destination would have to either be pretty damn appealing or remaining on earth pretty unappealing for any number of governments to consider financing that. Your return data from the new world would be retrieved only 100's of years into the future.

    Launching a smaller robotic mission using these new propulsion technologies might just be worth while though. We'd do well to get such a mission to stay working for as long as Voyager has though in the hostile environment of deep space.

  • Comment number 11.

    Well my two cents are: (follow the trend from history)
    1. Since it will take something like 80 thousand years for Voyager to reach nearest star and if interstellar travel will ever become practical then in x? centuries from now our civilization will blow by Voyager on its way to Proxima Centauri in some version of Alcubierre drive. So tell our veteran astronauts and dreamers to park their dreams until physics catches on. Yes we can go to Mars and Moon for now but just forget about other stars. The historical trend to follow is: don't even dream of discovering America if you just learned to swim, build a boat, a big boat take it for a spin to the nearest island and just relax until then. (Stop wasting money on engines that push it will not work!)
    2. SETI program should park themselves too. Everybody knows that in the past we used huge Antennas and Megawatt transmitters to get the noisy signal in some silly version of radio receiver. The signal was this massive blob that everybody could detect because it wasn't even filtered right and it sent harmonics and stepped over neighboring frequencies. Now just a hundred years later you will not even detect the signal in some cases because it is spread-spectrum and uses state of the art receiver capable of pulling signal right out of the noise floor and no longer needs the transmitter that will fry every bird flying in a mile radius of the 3 mile high antenna. Besides who said that advance civilizations would use radio signal that you have to wait on for years to travel between stars? They could use some form of quantum entanglement that would make instantaneous communication possible between galaxies.

  • Comment number 12.

    The Closer to the speed of light you travel, doesn't time effect you at different rates?

    I can't remember who's theory that was, basically if you where travelling at just under light speed, only hours could pass for you but centuries could pass on the ground.

    Was that Einstein?
    Mabe i'm just talking rubbish.

  • Comment number 13.

    One area of inter-stellar travel that could do with more research is radiation mitigation. An electro-magnetically charged outer shell to deflect gamma rays or some other idea perhaps. I think research into radiation mitigation would be worthwhile as it could have benefits beyond spacetravel, maybe being able to help with future Nuclear accidents here on earth. If such technology is achievable, it will be shown that there are real benefits to inter-stellar/planetary travel research that extend just beyond itself and thus help obtain grants & funding and show tangible benefits to people that maybe aren't interested in inter-stellar travel.

  • Comment number 14.

    But, a little over a hundred years ago a man would walk infront of a car with a flag because 3 or 4 miles an hour was a terrifing speed, yet HG Wells dreapt of The Anachronic Man, the first Men in the Moon and the Shape of things to come.

    Now one hundred years later, they are buliding a car to break the sound barrier, and writers dearm of Parrall worlds and "other dimensions".

    just because our minds at this moment in time cannot see a way to "make its so" tomorrow Telsa's heir may appear and build it. just because it cannot currently be done does not mean it wont be.

    That said we as a species will probably over populate the plant and dies of lack of resorces before we leave the solor system. IMHO

  • Comment number 15.

    @Hastings #2

    You seem to suffer from a delusion shared by many that modern physics is basically a done deal, that Einstien rules supreme and there is no 'Warp Button'. Personally I have no idea whether this is the case or not however any physicist will tell you that we don't really know how gravity works, don't have a clue what the fundamental makeup of the universe is and our best theories are unable to explain all of the current physical world.

    As an example if you calculate the actual energy involved in lifting an object to a height of 150 miles your will find its actually a small fraction of the energy used by our rockets. This opens the door for an anti-gravity device which consumes much closer to this theoretical amount of energy to do the job. Net result costs to orbit drop dramatically which has always been the main obstacle to serious space exploration.

    I choose to wait and see what the future brings. History is littered with examples of those who said something was impossible only to be proved wrong within their own lifetime.

  • Comment number 16.

    "This is a very interesting conundrum. It's something that has been pushed to the back burner for decades now as more pressing things have been found to spend the billions of dollars (inevitably) on"

    And this is the real barrier. Short term motivations and our financial systems inhibit our ability to reach out and take on these grand projects that will help the intelectual and visionary evolution of our species.

    The moment anyone mentions a time period that is beyond a human lifespan or an unfeasable large dollar attachment to a project it is all to often dismissed out of hand.

    We could, as a race, implement a hybrid drive system or even an Orion style craft and in a point in the future gaze in detail at the Centauri system but unless we are able to break from our limiting social and psychological structures this remains unlikely.

  • Comment number 17.

    One thing which scientists of today seem to forget is that our civilization is still very, very young, technologically - metaphorically, we have just been born and are taking our first few breaths. In the centuries to come, we will no doubt discover new physics which we can't even dream of at the moment. This will allow us to manipulate space-time and provide us with:

    massless propulsion
    warp drive
    zero-point energy source
    controllable inertia
    artificial gravity
    wormholes

    sounds far fetched? yes but so did supersonic travel, nuclear power, the internet, man-on-the-moon only 100 years ago.

    I reckon we will be a star-faring, fast than light civilization, within 200 years.

  • Comment number 18.

    A couple of years ago New Scientist did an article (cover story) on German physicist Burkhard Heim who described a way of looking at relativity , gravity, electrons, atoms etc which allowed for a hyperdrive that would take us to Mars and back in 5 hours and bring the stars within reach. The New Scientist article can be seen here: http://tinyurl.com/burkheim or in full with additional links here: http://tinyurl.com/burkheim2 The article indicates that there was going to be a practical test of this theory, it would be interesting to know what the results were.

  • Comment number 19.

    Would you want to leave almost everyone you love behind to live and die in a metal tin without any chance of reaching your destination?

    Those travelling on London's Northern Line will know exactly how that feels..

  • Comment number 20.

    It seems the only thing really stopping humanity from continuing to investigate the rest of the Universe is our financial system. Many posts talk about the 'cost', the amount in dollars/pounds/euros/chickens it would 'cost' to achieve these dreams.
    As a species we have access to the talent required to build whatever device we can imagine, even if this takes time our brains will get us there. We have the people who can build what others can imagine, yet more who would or could make the trip. We live on a planet that physically has all the resources we need yet we continually hold ourselves back by constantly deferring to a financial system.
    This is a human construct that is completely imaginary and made up; remember the fantasy numbers of $/£/E that were suddenly created when the system was about to implode a couple of years ago?
    If it came down to it and we knew the Sun would explode in 50 years, would we really be sitting counting little bits of paper with pictures on or little discs of metal with faces on that have absolutely no real value whatsoever? Or would we be forging those materials into a shape and form that would carry our species to safety?
    This is the real next step in our evolution, if we can't see by this monetary fascination, if we can't evolve then we die out like every other lifeform whose environment changes and who do not adapt. IMHO.

  • Comment number 21.

    Stormbrook and Richard reflect my own thinking quite closely. No manned mission to a planet since the moon landings 4 decades ago tell you that there has to be a huge and largely 'selfish' imperative before mankind earmarks sizeable junks of GDP in similar projects. In the 60's it was the cold war that led to the space race and subsequent moon landings.

    I can see that robotic probes will continue to explore the solar system for a good while and there may even be a successful manned mission to Mars within the next 20 years. But forget about generational colonies on Mars or the Moon in our lifetimes and 'worldships' will probably never happen. Maybe small asteroid mining camps will happen by the end of this century thanks to the likes of electric engines.

    But perhaps AI will be feasible in the next century - compact ships with human like trates might explore other star systems by proxy and send us back preserved genetic tit-bits and analysis.

    I do hope I'm wrong though and that some new discovery not even imagined opens a way for us to explore and colonise properly.

  • Comment number 22.

    I should think that focus on interstellar travel and human colonisation of another planet will only really gain serious momentum when our species gets to the "oops" point of realisation that our continued existance on this planet is under direct and enevitable threat of ending.

    Project Orion is a non runner solely because of the radioactive mess it leaves in it's wake.

    For such an interstellar project to become anywhere near a reality will require a space station many many times bigger than present, to enable space manufacture assembly of a ship of a size capable of maintaining a population of 100+ people for a duration beyond the lifespan of those initial inhabitant explorers. Such a vessel would need to be of a somilar size as a very big ship/cruise liner with the ability to break into 2 or 3 self supporting parts parts in event of emergency.

    We would also need to include substantial weapons systems/abilitys as it would be pointless to find somewhere suitable and then end up as munchies for a 30 foot centipede or dinosaur or whatever strange creatures may exist there.

    Then theres the export of God, do we take this with us or leave such fantasy theological beliefs behind.

    The logistics themselves to enable all this would be "out of this world".

    With present technology and travel speed abilitys, those who reach another habitable planet will not be of this world or any other.

    I would think that any such travel will actually require a much larger number than 100 personel due to the need of so many different skills over such a duration and even then the skill base will need to be multi-functional.

    You then have the issue of educating the next generation born aboard, to the same/realistic standard of competance and also maintaining an ageing and increasingly disfunctional population and may even require a policy of assisted suicide once a level of individual disfunction is reached.

    I doubt that any such project will ultimately be viable until we are able to colonise the moon and also able to substantially increase the size of vehicles for transport of people and materials to the moon.

    Raising the funds and obtaining resources/materials for such an expedition will require multi-nation or even United Nation re-sourcing and some form of investment return of value/wealth or whatever for each and every nation/part that is involved.

    While some nations may not have the money, they may have raw useable materials which can be used as their donation/investment.

    Due to the very nature of the whole being of greater importance than individuals, the rights of each would need to be far different than is presently accepted here on earth today in our "civilised" countrys.

    Life & death will have different meaning and value and a regime will need to have the power and ability to enforce and maintain those values.

    Once, if such a destination is achieved/achievable, then the colony which will be a new generation born and educated in space will have evolved its own values and morals which will most certainly be at odds with those back here on earth.

    Such a colony, if it were to be successful and eventually return at some further distant point in time, it may be that it might want to impose its own new values upon us, or at least those who exist in the future on earth, just as was the reality of Britains colonisation of America, but in this instant with much greater difference and even opposition of opinion.

    I think that such stargazing is just a pipedream at least for the next 25 to 100+ years, especially with the way the present world systems function/disfunction, but then again demand and need are the main drivers of everything hence events on earth etc could easily create the environment and necessity for such a project as presently all our species existance eggs are relatively in one basket, namely the basket called Planet Earth, and it already has damage and is liable to further huge damage from any number of sources/events.

    Factually, out there, somewhere, is our species future, like some viral plague relative to bacteria viral infections which evolve to jump species here on earth, we endemically need to evolve the same way to jump planets and infect them with our existance.

    Along the way, we may even come across something with something similar to a fly spray, who may see us and regard us in the same way as we see/regard bird flu.

    The prospects for interstellar travel is pure escapism, presently either a daydream escape, or a future necessity.

  • Comment number 23.

    Who say we can't achieve faster than light speed? Did you remember if you say to them you broke the sound barrier prior to the 20th century, they will think you are crazy and yet the barrier was finally broken in 1947? Did you also remember many people think space flight and travel to the moon are impossible and yet it is achieved in 1961? FTL travel is possible - it isn't about if it will happen but when it will happen.

  • Comment number 24.

    The main problem is that we are currently bound by our own understanding of Physics. It wasn’t so long ago that the most brilliant minds thought the earth was flat, and that breaking the sound barrier was science fiction. If we step back for one minute and appreciate that our species understanding of material physics is flawed, then I think we may be on the right track. I can see no victory if we continue down the route where relativity is judge and juror, and every theory and planned and executed within these parameters. As far as saying we ‘must’ be the oldest relative in the neighbourhood as we haven’t heard anyone else out there, would you want to have a conversation with a door mouse?

  • Comment number 25.

    I think we ought to start by setting further and further distance records. I think it's good science to do things you've never done before. Sailing round the world would have come as a surprise to people that thought the world was flat. Similarly the effects on time of traveling at 10,000 mph would have come as a surprise to people that only knew Newtonian physics. There's the Pioneer anomaly that's still an open question for a start. We just assume we know what space is like, and the laws of physics are the same throughout the universe, but we've never actually been there. By 'we' I mean probes and experiments, something that's actually doable rather than far flung fantasies about manned space travel. We need better circumstances for accident discoveries than space caravaning 200 miles above the earth, as important as that is.

  • Comment number 26.

    It makes me sad to see so many seemingly intelligent people dismiss things on the grounds that modern physics is the last stepping stone and there are no more advancements beyond our current knowledge.
    Just remember, it wasn't too long ago when people thought the world was flat and the Universe was static.

    If we've been wrong before, who is to say that we may never find this elusive "Warp Drive" button?
    Open your minds people and learn from the past. We don't know everything.

  • Comment number 27.

    Surely the reason to want to travel to new worlds is not for science alone but for humanities sake, namely to ensure the continued survival of the human species. At the moment we have all our eggs in one very fragile overcrowded basket.

    For sure we have the ingenuity to create the technology to make a generation ship a reality and if we start now at least we have a chance, unfortunately there is no drive, there is no short term gain for such a huge project, so there will be no economic drive to get a project such as generation ships of the ground, as we know humans are very short sighted. One day soon it may be too late!

  • Comment number 28.

    Just to comment on the logic from Hastings earlier on in this blog. I cannot see where the conclusion that we are the most advanced comes from. If a race 1000 years ahead of us in technology is 1000 light years away, then if we hear them it will be at our current state of development.
    As for Scottie breaking the laws of physics, well the Enterprise must have been operating to laws not yet discovered... well that is one get-out.
    I believe that we will not be able to travel in straight lines to other systems, but if space is curved, or we can find the so-called wormhole mechanisms then we may have a chance, fat perhaps, but science has always produced surprises, so why not in this field.

  • Comment number 29.

    One of my favourite movies is 'Deep Impact' partially because it has both Robert Duvall & Morgan Freeman, but mostly because pretty much everything that can go wrong in attempting to stop the giant asteroid DOES go wrong and that is both realistic and refreshing in a Hollywood movie.

    The situation in the movie is one we could face.... having a space craft capable of getting out there fast and tackling a rogue asteroid as far from earth as possible seems sensible and that justifies investment in this sort of tech ASAP.

  • Comment number 30.

    Fedya: No species can advance beyond radio waves without first having transmitted some, therefore SETI isn't pointless. We are very unlikely to have heard from any species yet having only been receving radio waves for around 60 years and differentiating their origin for a lot less. Coupled with only 'listening' to a very small area of the sky it's not hard to see why we haven't heard anything yet. Any species which transmits waves will stop transmitting if they become extinct and if that 'band' of waves does not reach us when we are capable of understanding it then we will never receive it. We may be extinct before it arrives or it may have already past us by. The species transmitting it might have been extinct for hundreds of millions, if not billions of years. It's about as likely as finding a needle in our solar system using only a metal detector with a 4 metre range. An absence of evidence is not evidence of absence. It's a certainty that other species do exist, probably millions of them in the universe.
    I don't think interstellar travel is unlikely, I think it's inevitable. We cannot base what we currently know and our current capabilities on what will be possible in the future. Even our current knowledge of physics is far from the finished article and therefore we don't even know all the rules of the game and so cannot possibly expect to understand how to win at it.
    Looking at how technology has advanced over the last 100 years and the fact that as technology advances the whole process accelerates (i.e. computers have become more powerful within the last 5 years than they have done in the 50 years prior to that, and many other things are similarily progressing).
    Interstellar travel in a normal human lifetime currently appears impossible. Even if you were able to propel a spacecraft to a velocity of 99% of the speed of light then you would have other issues to deal with. Issues such as space particle collisions. At such a high velocity even hitting a single atom would be a catastrophic collision (F=MA), hence why Professor Hawking advised that a forcefield would be required. Even at this speed the distances would take an enormous amount of time so to be able to survive would require you to house a large number of people in the ship to reproduce. The ship would also have to be very fuel efficient; something I believe that Nuclear Fusion would be required for(the same reaction which keeps our sun burning for billions of years).
    Despite these boundaries, and many more which I have not listed, the fact that we are able to even comprehend it's possibility with today's technology means that tomorrow's technology will make it a reality.

  • Comment number 31.

    This is really fascinating but I feel that our time on earth is running out due to an unsupportable population and global warming, which means that we may all be gone before we have a chance to develop the technology needed to escape earth.
    Sorry to be so pessimistic!

  • Comment number 32.

    At 12:23pm on 16 Mar 2011, Richard wrote:
    I would suggest you look up Kardashev and specifically Class II. Whilst probes along the lines of a StarWhisp are possible along with other interstellar microprobes in the medium term. Our nascent Class II civilisation. IF IT GETS PAST THE TROUBLES: Climate Change; Peak Oil; Peak Water; Peak Everything Else, will, by necessity, have learned how to utilise the: NEOs; MBOs; MBCs; Trojans and eventually ...the Oort Cometary Halo. Where Ice makes for a good power source (Fusion) and fuel and radiation shielding! Also since the Oort is halfway to another Oort around AlphaCent (just a guess) the distance for the interstellar 'hop' is around 3 lytes. We don't need Star Trek just Space Colonies.
    Finally I would direct you to the term Bubbleworld
    Dandridge M. Cole and Donald W. Cox "Islands in Space: The Challenge of the Planetoids."

  • Comment number 33.

    23. At 1:03pm on 16 Mar 2011, chirojupiter wrote:
    Who say we can't achieve faster than light speed? Did you remember if you say to them you broke the sound barrier prior to the 20th century, they will think you are crazy and yet the barrier was finally broken in 1947? Did you also remember many people think space flight and travel to the moon are impossible and yet it is achieved in 1961?
    ____________
    'Many People' think many stupid things. You'll find far fewer scientists or those with a good science education saying the same things.

    A bullet travels far faster than the speed of sound as did the V2 rocket (1800's tech & 1940's). For a man to break the sound barrier was simply an engineering problem: aerodynamics, strong airframe, big engine, control surfaces capable of moving in the air at high speed. Going faster than light in a straight line* violates the very principles of the universe as we perceive them. Its like making a perpetual motion machine... impossible.

    *crossing dimensions is the way to side step this problem (not that I'm suggesting its easy. The simplest way to explain it is to imagine a sheet of A3 paper held in portrait. From the top of the page to the bottom is about 60 cms. Roll the paper into a cylinder and top and bottom are 1mm apart. If you can warp the fabric of space you could possibly achieve a similar effect without violating the laws of physics.

  • Comment number 34.

    Developments like these are very important, but realistically we'll not be building an interstellar generation ship any time soon. However, scoping these out can give us ideas for the spread of our civilisation out to other off-world areas of our own solar system, and that very much is something that we should be doing. If we can build up our technical expertise in engineering on a large scale in microgravity, then we can dream even bigger in terms of setting up (potentially) truly vast ships containing tens of thousands of people who would be a living active community - a *city* - heading out to investigate the stars.

    And of course we would be able to do that again and again and again, until we've exhausted the resources of this solar system :-)

    @shanemuk

  • Comment number 35.

    #25 & #26. The idea that people used to think the world was flat is a myth dating from a US author in the 1850s. Those who actually cared (when most people never left their village few did care) knew full well it was round. A 13th century monk 'proved' it by pointing out that as you walked towards lincoln the first thing you saw was the top of the cathedral spire reaching above the horizon. If the world was flat the whole cathedral would be visible (just very small) for as long as you had clear line of sight.

    People in the past weren't stupid... far from it. They needed to think to stay alive. Their knowledge was limited to their perception of their universe. The laws of physics AS WE PERCIEVE THE UNIVERSE are absolute but we only work in 3 dimensions and are aware of a 4th (time). Most reputable physicists accept there are far more dimensions than the 4 we exist in.

    #22. At 1:01pm on 16 Mar 2011, MrWonderfulReality wrote:
    "Project Orion is a non runner solely because of the radioactive mess it leaves in it's wake."

    Only if you fire the atomic engines within the Earths atmosphere. Fire them up in space and it would be like pouring a pint of tap water into the atlantic ocean. Space is radioactive as hell... what comes out the back of the engines would make no difference at all and the 'fallout' will be dispersed to the corners of the solar system.

  • Comment number 36.

    Don't we need to either crank up the rockets' speeds or solve the cryogenics problem? If we don't we'll need to pack nappies for interstellar travel...

  • Comment number 37.

    What is the minimum amount of computation power you would want to send in an unmanned mission? What is the minimum amount of instrumentation and on site propulsion you need? Should we fly by or enter orbit? Using Moors law, the total mass delivered need not be large. Maybe small enough to use solar sails for deceleration. Engineering wise, I think we could launch unmanned missions in 20 years. Unmanned flight times less then a century are not unreasonable. Sending a human crew is vastly too expensive but sending a virtual crew who actually believe they are on the Starship Enterprise is within reach.

  • Comment number 38.

    14. At 12:35pm on 16 Mar 2011, Kevin Rolfe wrote:
    But, a little over a hundred years ago a man would walk infront of a car with a flag because 3 or 4 miles an hour was a terrifing speed, yet HG Wells dreapt of The Anachronic Man, the first Men in the Moon and the Shape of things to come.

    Now one hundred years later, they are buliding a car to break the sound barrier, and writers dearm of Parrall worlds and "other dimensions".
    _________
    A little over a hundred years ago trains in Britain were going faster than they do now! 120mph was quite normal. Even a man on a fast horse can do 30mph. The "flag man" was because early cars were very, very hard to drive.

    Incidentally the sound barrier was broken in a car a few years ago. The current goal is to break 1000mph.

  • Comment number 39.

    What holds us back is not the laws of physics - formidable as they are - but human nature as expressed in our political and social structures. If humanity was a single hive society totally comitted to expansion the world ships would already be on their way.

    Which takes us to the Fermi paradox - where are the alien world ships that should have arrived centuries ago?

  • Comment number 40.

    Just one question: Who are we going to out on the B Ark?

  • Comment number 41.

    Space exploration will never move far until we can break free of Earth's gravity without using a rocket. A space elevator would be a big help but it doesn't solve the problem of lifting off from other planets (I also can't see one being build in the next century). We need something like the ion engines in Star Wars that can reach deep space without needing a large amount of combustible fuel to produce the necessary thrust (and a large amount of fuel to carry that fuel and even more to carry the extra fuel and so on...). If we can go even further than Vasimr and to produce an electron / ion engine of this calibre then space exploration would explode.

    To put it in perspective - a sustained acceleration of 10m/s^2 would mean that you could arrive at Mars (at closest approach) in 2-3 days and Neptune in a couple of weeks. Allowing acceleration at ~1g also means there wouldn't be the negative health impacts on humans due to weightlessness.

    I don't see any physical law that would prevent this sort of acceleration in an electron or ion engine. The problem is that the flux of particles of such an engine would have to be orders of magnitude larger than currently possible and at the same time it is necessary to keep the particles at a high velocity/mass ratio. All we really need is an engineering genius to come along and work out a practical way to achieve this.

  • Comment number 42.

    I think that if we crack quantum mechanics to the point where we use nanobots to create fuel & food from very little we may have the building blocks to sustain life in space, and once the speed/time issue is resolved anything is possible.

  • Comment number 43.

    Further to TallBlondJohn's comment about the Femi paradox, if more intelligent life exists in the universe there is a high probability that they are able to disguise themselves from us with ease and have had 'a look' at what we are like & up to, and decided that they dont like what they see and are keeping well away?

  • Comment number 44.

    I agree with Ian's comment (post 20). The way we are currently forced to live and think is what determines what we can and cannot do. Money is a conduit for control. We need to open our minds to that which we know. Science is also governed by money. What science is allowed to discover is controlled by the money creators.
    Their exists in Nature a creative force. This force is the creative process that produces all that surrounds us. Science believes that energy cannot be created, and that energy is simply transformed from one energetic form to another. This is incorrect. Nature is the very definition of creation. For every process or force in Nature you will always find an opposite. If an opposite cannot be found then you must question the initial force or process so say discovered.
    Explosion is a process Nature uses to degrade and destroy, science does not know it's opposite but you can teach yourself by simply reversing that which you know about the Explosive process. Why not give it a go! You'll be amazed what you soon discover!

  • Comment number 45.

    39. At 2:33pm on 16 Mar 2011, TallBlondJohn wrote:
    "Which takes us to the Fermi paradox - where are the alien world ships that should have arrived centuries ago?"

    Even a hundred years ago they may have sailed right past without realising anyone was home (or if an unmanned probe odds are it crashed into an ocean). Its only relatively recently we've started blasting electronic noise into space and lighting the place up when it gets dark.

  • Comment number 46.

    Voyager was catapulted using the gravity of the planets.There was no need for lots of chemicals or nuclear explosions.Even before you consider interstellar flight,you need a deflecter shield for protection.A tiny dust particle will rip your spacecraft up at high speed without one.Scientists have shown a weak magnetic field can be used to deflect space particles,even creating a magnetic field that will protect a moon base from solar flares.
    Even if you had instant warp travel or jump from point to point faster than light,when you look into space you see the past.From earth to a star in orion instantly,wow,it goes super nova ,your dead and on earth yet to be seen because of the limints of the speed of light.All intersteller travel would first be carried out by machines with artificial intellegence.We need exotic fuels and propulsion.Can the science fiction of star trek be made real?
    If the calculation for life in the galaxy is correct,once in space those people more advanced than us might stop us or ask us to join them.

  • Comment number 47.

    Another rather more mundane problem is that the ship will need artificial gravity. Humans do O.K-ish in zero gravity for long periods but you get significant muscle wastage (which can to an extent be countered with excercise) but also leaching of calcium from the bones. Cosmonauts in Mir who were up there for 12months plus lost 1% of the calcium in their bones a month.... after several years you effectively have brittle bone disease. Immune cell & blood cell production is also adversely affected by zero gravity. No human child has yet been conceived and born in zero gravity but we've experimented on animals and had some odd results.

  • Comment number 48.

    A Fred Pohl story called "The Gold at Starbows End" covers a lot of the issues you've brought up, Jonathan. Things like the journey's length and how the crew occupy themselves plus the extra information that is acquired as time passes and is passed to the crew.
    The consequences that some of this extra later information might be bad and the effects on the travellers is also explored.

    The key thing for me is that our imagination actually expands further than our capabilities and not everything that we imagine is actually possible, or true.
    The truth for me is that we are already on a spaceship plummeting round our sun at 30 miles a second and towards Sagittarius at 80 miles a second. Much is made of the food, plants, stores and equipment that must be taken on an interstellar voyage, but if we cannot manage to survive on our Earth now with what we already have, then what hope when we get anywhere else?
    Currently, it takes 7 whole earths to satisfy the USA's demand for food and energy and the EU nations need three earths.
    The plain fact is that we are stuck on one earth and we can't get off. If in some future time all 7 billion of us manage to co-exist within the bounds of the one earth consumption level, then that will be the time to consider if we can make it to Antares 5, or whatever. For now, it must stay in the realm of our imagination.
    This isn't pessimism on my part, just pragmatism. I'm optimistic for our survival as a species for some time yet, but a handle must be made to grab our chance at the near future now to facilitate this.

  • Comment number 49.

    @Strangely. I remember discussing this separation issue a number of years ago at a conference in Boston. After many decades, the World Ship might have difficulty communicating with Earth - not only because of the distance, but also because the language on the vessel and on Earth would develop in different directions. We could become mutually unintelligible. Also, separation is very likely to result in speciation over time - they would be a different Homo to us (assuming our Homo hangs around that long).

  • Comment number 50.

    @Peter Sym – “#25 & #26. The idea that people used to think the world was flat is a myth dating from a US author in the 1850s. Those who actually cared (when most people never left their village few did care) knew full well it was round. A 13th century monk 'proved' it by pointing out that as you walked towards lincoln the first thing you saw was the top of the cathedral spire reaching above the horizon. If the world was flat the whole cathedral would be visible (just very small) for as long as you had clear line of sight.”

    You are missing the point, and in your attempt to correct me you are also proving the very point I was trying to make. You accept the fact that the earth is round as you now know through satellite imagery and thousands of other measures that of course the earth is not flat, but back in the 13th century although people may have theorised that there was not simply and edge of the world where you would fall off, the idea of a spherical earth was not widely recognised or accepted. You say the laws of the universe as we perceive are absolute but we only work in 3 dimensions, well then they are not absolute. Physicists acknowledge there may be more than 4 dimensions but they are no closer to understanding how or in what form they exist, and in that sense are just like the people who knew they wouldn’t fall off the edge of the world, but had no idea what would stop them. If we try to evolve by only looking forward we will never know what mistakes we have left in our wake.

  • Comment number 51.

    The armour requirements for the space craft maybe aren't as bad as some predict. Space is virtually empty but we've been operating space stations and very lightweight craft around earth which is full of junk. A bolt from an old Apollo rocket hitting the international space station hits at anything up to 19 kms a sec (a rifle bullet travels at less than 1 km a second initially and slows down greatly). For 40 years we've used the principle of spaced armour using little more than tin foil several inches apart.

    This explains it in better detail:
    http://en.wikipedia.org/wiki/Whipple_shield

  • Comment number 52.

    #50. Where's your proof people though the earth was flat? Its a complete myth. Most people didn't care and those who did knew better as can be shown in literature going back 1000 years. A flat earth defies even basic observations and raises questions like 'why doesn't the sea run over the edge'?

    The majority view was that the sun orbited the earth (which based on observation it does...apparently... cross the sky as if we're stationary and it isn't) That might be a better example of drawing false conclusions based on whats perceived to be the case.

    To argue that the laws of physics as applied to our universe aren't absolute is to imply that a perpetual motion machine is possible... you won't convince many people of that. I'm open to the concept of faster than light travel but not from A to B in a straight line & in 3 dimensions (time of course would stand still at the speed of light). The only way round it would be to use other dimensions where other laws apply and thats WAAAAAY beyond my perception.

  • Comment number 53.

    Peter_Sym - It is one problem (gravity), but can be got around reasonably easily with centrifuges and such, which, if you've managed to build a ship capable of supporting life for thousands of people, should be achievable. Clarke's Rama ships did this rather elegantly. I imagine they were quite expensive though.

    With regards to interstellar travel, I've no doubt we'll achieve it one day, but when or by which means I have no idea. I'm focusing on the solar system for now, sitting here and hoping that Polywells will take us there. When we've established ourselves around the system that is our cradle (we're still in the womb, as far as I'm concerned), we might finally begin to seriously consider the interstellar problem.

    foojamme - was that a hitchhikers reference? I do hope so. Round up the telephone sanitisers immediately.

  • Comment number 54.

    Unless we are completely wrong in our understanding of the laws of physics manned interstellar spaceflight is likely to be unusual and exceptional. It is difficult to imagine any society building a large interstellar spacecraft unless it was absolutely necessary for survival. It is difficult to imagine our society building a large interstellar spacecraft under any circumstances. However we can and should send unmanned probes to nearby stars. Already we have discovered planets around a number of stars and we are close to being able to identify Earth like planets. The next step is to send a probe. We should forget about rockets and all other similar devices and think solar sails and guns. We could within the limits of existing technology design a miniature probe and a means of accellerating it to a reasonable fraction of the speed of light. Planning a mission that might last thirty years is not beyond the bounds of possibility. The design and manufacture of an interstellar probe would be a great technical challenge but it would provide a great stimulus to the development of useful technologies which would not have been discovered in any other way.

  • Comment number 55.

    #17 normal-thinker, I completely agree.

    We're kind of judging our long term future in space by the limitations of today's technology; we are so young as a technological race that I wonder whether it's best not to start spending money on researching 'generational ships' and such like, but instead plow resources into trying to make science-fiction a reality.

    If I, as a scientist, was talking about travelling to the Moon 100 years ago, I'd have been laughed out of the room. Why does the scientific community act in such a retrograde way? Is it egos or a fear or embracing the fantastic? A fair of failure if something fantastical doesn't work?

    We need to think in future terms if we're going to get there, and not just creak along at a sedentary rate.

  • Comment number 56.

    What we really need is a really really big war.

    Maybe that way technology will advance fast enough to make this more likely.

    Phil

  • Comment number 57.

    @ Joe Chip

    Certainly was, thanks for noticing. Hairdressers, tired TV producers, insurance salesmen, personnel officers, security guards, public relations executives, management consultants should carefully consider their positions too.

    On a serious note, fiction related, where are the sentient machines or spaceships, as described by Iain M Banks? They seem a perfectly reasonable suggestion as to the possibility of intelligence elsewhere and one who would not particularly mind the length of a sub-light journey. Perhaps they are or have been here in avatar form. Shouldn't we be aiming to create an entity that can act as an ambassador as well as a scientist and observer?

  • Comment number 58.

    A really good article and quite interesting , the thing that annoys me about space travel and the human race is that we are the equivalent of the dinosaurs in the 21st century. With all our technological might and our great scientific acheivements mankind has yet to colonise another world. Had only the space race competition kept going without the threat of war man would be living on mars right now. It was the drive behind the space race that got Gagarin in space and the US to the moon.
    We have no drive anymore , the excitement of space exploration has readily been replaced by celebrity lifestyles, sports personalities and
    X factor. Our nations need to put the drive back into space exploration otherwise we are doomed to mass extinction on this seed world.
    I advocate the expansion of the human race into our galaxy the quicker the better!

  • Comment number 59.

    I really enjoyed reading your article. There really aren't enough of these thoughts floating about at the moment.

    I just wanted to throw my 2 pence in.

    When talking about interstellar travel we only think about it from a local view point. For example, if you could travel at say 99% the speed of light you could reach our nearest star after the earth within 6-7 years. That's the observational view from the Earth, but from the observation with in the ship that time would be drastically shortened to about 9 months. So travel between stars is possible within our life time, it's literally just the will of the human race to move in the right direction.

    Let's be honest, even 50% of the speed of light would be a step in the right direction...

    Which by the looks of it we aren't, we're more interested in religious and economic beliefs and something without financial return in this world is worthless.

    Just a thought to chew on.

  • Comment number 60.

    @#11 Fedya & #30 AMcHarg - Re Modulation

    Making the assumption that electromagnetic waves are used by more than a minority of advanced civilizations, it seems natural that some fairly advanced modulation would be used. The most efficient such scheme is UWB (ultra wideband), a name we give to a "technology" but which is really as fundamental to future communications as, say, the Turing Machine is to computing.

    In such a scheme, the channel is defined not by frequency, but by a pseudo-random stream of symbols. Without access to the underlying key, the signal is completely undetectable.

    On the further assumption that advanced civilisations prefer to wait until we have already observed the constituents of their atmospheres, thereby forcing a fundamental change of world-view prior to contact, such streams can easily be made undetectable, by use of symbol sequences which cannot be tested for without access to computational power currently beyond our reach.

    That said, SETI is a source of wonder, and prepares us better for the future - regardless of the actual values in the Drake Equation.

  • Comment number 61.

    Just had a thought, if we could travel faster than light, we'd leave an awful lot of light pollution in their wake. Ships would emit light & leave it behind (only being able to travel at normal light speed). Commonly travelled routes would end up with ghost ships that weren't there!

  • Comment number 62.

    There's actually no need to exceed light speed (and currently no evidence that we can). Due to the time distortion effects of special relativity anyone on board a ship travelling at an extremely high percentage of the speed of light would only experience small travel times.

    In fact you could get to Proxima Centauri in just a few seconds relatively speaking if you had enough energy. Of course to an outside observer for instance on earth you would still appear to take more than 4 years, but I don't think that's very important.

    It would still take tremendous amounts of energy though, so hardly something we could think of in the immediate future.

  • Comment number 63.

    This article omits to mention that as far as currently accepted physics is concerned, faster-than-light travel is impossible.

    Meaning that even with the best conceivable propulsion systems, planets 30,000 light-years away would still take 30,000 years to get to.

    Interstellar travel is a dangerous fantasy because it encourages us to believe that we have other options if we trash this planet. We don't.

    To get an idea of just how empty this part of the galaxy is, consider that there is nothing but vacuum between our solar system and Proxima Centauri. According to the article, Voyager has averaged just over half a billion km a year, or 57000 kmh. At this rate it would take another 76,000 years just to reach Proxima Centauri.

  • Comment number 64.

    "this technology is likely to be fitted to the International Space Station in the next few years to help boost its orbit"

    Excellent - I've long suspected NASA are secretly planning to convert it into an interplanetary spaceship.

    "their supreme efficiency means they can go on thrusting for extended periods"

    Klaus, be gentle with me! Er, I'm sorry, my mind has wandered...

  • Comment number 65.

    At 4:04pm on 16 Mar 2011, Jonathan Amos wrote:
    One is reminded of Carl Sagan's "Cosmos" where he hypothesised the two waves of humanity sweeping clock and counter-clockwise through the galactic disc. Only to meet itself on the far side and fail to realise or remember their common origin.

  • Comment number 66.

    The future for longer distance travel will surely be robotic in nature.
    Scientists could of course eventually find how to use another dimension...to allow us to simply 'step' out of our solar system. That one is some way off, I grant you.

  • Comment number 67.

    Although I have not read every comment in detail I get the impression that the discussion in general relates to the physics of the problem and no consideration is given to the current advances or potential advances in the biological sciences. Relevant to the discussion I should imagine is the current research regarding immortality and biological engineering. I find this a little surprising since the science fiction writers have explored this aspect of future deep space exploration in a wide variety of senarios.

  • Comment number 68.

    Sideliner says:
    "Interstellar travel is a dangerous fantasy because it encourages us to believe that we have other options if we trash this planet. We don't."
    Interstellar travel is realistically further away than being able to create a sustainable future on this planet. Just because there needs to be considerable scientific effort expended on figuring out how to adapt to or reverse the damage being done to the planet, that doesn't mean we shouldn't allow scientists to consider research into interstellar travel or other areas. Science is about inquiry into whatever individual scientists deem fit to research. The results yielded by their discoveries can benefit us in ways unknown, like the rather overused example of Penicillin.

    And Sideliner goes on to say:
    "Voyager has averaged just over half a billion km a year, or 57000 kmh. At this rate it would take another 76,000 years just to reach Proxima Centauri."
    Actually, Voyager will pass within 1.6 light years of AC+79 3888 in about 40,000 years. Although currently AC+79 3888 is about 17.6 light years away, in 40,000 years this star will be about 3.45 light years away as it is apparently rapidly approaching the Sun.

  • Comment number 69.

    Alcubierre drive is the key to interstellar drive. It was an idea theorised by a Mexican physicist named Miguel Alcubierre. He proposed an idea where by you contract the fabric of space in front of your craft and expand it behind, therefore allowing a ship to travel to its destination faster than a beam of light would take. Also the craft would not be subject to the problems faced by conventional means such as time dilation and inertial factors like high Gs because space time is being manipulated around it rather than the craft is moving forward at a high velocity through flat space time.

    The trouble is that our technology at this moment in time is not at a sufficient level to build such a propulsion system. Hopefully in the future once we have gained a greater understanding of gravity and how to manipulate it, something like an Alcubierre drive will be possible.

  • Comment number 70.

    I agree with Normal-Thinker's post when he says there is so much we do not know about how the universe works and i belive that we will find a way somehow and at sometime in the not too distant future to traverse interstella space very quickly. Just because we do not know to do it now, does not mean we never will know how to do it.

    I belive the impetus will come when an exo planet's atmosphere is analysed and found to contain the chemical footprints of life, either by ...is it called... gravitational lensing; or some other way and maybe natural resources are found on the planet as chemical traces. I belive then , that either governments will fund proper research into stelar drives as a matter of urgency , or even a Richard Branson like Space prize project will be started to discover a way to build a super luminal drive or something of the like, to get to the planet in the least possible amount of time to have a look at it.

    As for the SETI argument.. well, someone said it before i think, that we are probably searching for the wrong kind of signal. Perhaps advanced aliens do not use radio at all to communicate. The whole idea is that they are aliens .. something different from us, and prob with a whole different set of needs and desires, ideas and tech from our own.

    It would be amazing if at some point we were to find out, that aliens are already in our galactic neihbourhood, either watching idly by, bored out of their alien skulls, as we grasp with the fundamentals of getting around on the galactic stage and then maybe worthy of contact with them, or they could not really bothered about our existence at all...and let us get on with finding our own way in the cosmos.

    but as we already know, truth is stranger than fiction..

    a beintot

  • Comment number 71.

    Hundreds of people on a world ship travelling for decades............errr, what they going to breathe?

  • Comment number 72.

    @70 jasonalpha

    Aliens won't be bored. They'll have alienInternet, alienTwitter, and alienFacebook.

  • Comment number 73.

    If one takes particular note of the technological progress of mankind (sounds a bit pompous- but it stands as a proposition) then all deceptively looks fairly progressive towards eventual,"interstellar travel". But, take a good look at the world's populace and assess its mental and emotional progress: it's care for the world, the environment, the wars, the crimes of nations of all kinds, the cruelty and the general inward-looking attitude.
    All right: there are saving graces; heroic actions; quiet, unselfish philanthropy and the will by some to do away with the negative things; but there is no general Evolutionary Leap to world cooperation and the absence of military and criminal conflicts...Without the necessary-vital- groundswell of care for the world as habitat and it's living things, there can be no space travel on the scale presently dreamed of and written about by large numbers of optimists. To reach out to the far-flung places of space, it will take the Minds as well as the best physical humans to do it. That would take a human kind far different than that which exists today, because Space has no practical limits, has immense dangers, and demands an unparochial caring spirit; not weighed down by petty quarrelsome feelings and selfish ambitions. The Moon, the planets of our system, certainly; beyond that requires the springboard and support of Earth itself. How can that be when we seek to destroy it.

  • Comment number 74.

    Surely biostasis ("suspended animation") is a much more practical proposition than generational ships. I've little doubt this is achievable (it's apparently quite easy to achieve with certain small animals).

    Exotic FTL drives are fun to speculate on, but most of the current theoretical approaches have problems like requiring large amounts of negative matter, which we've no idea how to make, or requiring more energy than the universe contains.

    It's a mistake to think of the speed of light as a barrier like the speed of sound. It's like an infinitely high wall, not to be passed by climbing. You can pour all the energy the universe contains into a single electron and it still won't achieve the speed of light.

    If you can do it at all it's likely that the default FTL speed will be infinite and that lower FTL speeds would require more energy.

  • Comment number 75.

    It is foolish to think that the boundaries of modern science is the limit of science. We are seeing advancements in our lifetimes that even decades ago people would say were impossible. You just need to look at the speed certain things advance at now to realise the potential.

    However, space travel isn't that much more advanced that it was at the very beginning. Perhaps it is not like mobile phones or computers or what have you, where the technology advances at an ever quickening pace.

    Perhaps space travel is like swords or sailing boats. Maybe the technology we have for them now won't change for thousands of years because the next step is more like a huge leap.
    Or perhaps not. Maybe we just haven't had the motivation...

    1 more thing though. If there are 30000 other Earths within 1000 Lys, where are all the aliens? Are we the most advanced intelligent life? The ONLY intelligent life? Is earth unique with regards to life? Or is space travel really just that hard that nobody has been able to travel between stars? Maybe the aliens have their own version of the prime directive. Maybe we just haven't been looking in the right places.

    I find this sort of thing fun to think about when bored.

  • Comment number 76.

    Well based on current known laws, time & space etc, relativity it is always going to require generational ships to reach out into the cosmos.

    However, it is what we don't know not the known that is the exciting future and it is that which should motivate.

    Physics is important but only relevant in the 'now', not the future 'now'.

    For now we accept current understanding and limitations of science. but then the ability to bend light, lasers, food heated by invisible beams all seemed impossible according to the known laws.

    For us living in the now, my gosh it is so frustrating, we can see the future, we now know other planets are calling, when fifty years ago we had to rely mostly on asimov, clarke and harry harrison to give us the dreams.

    We are talking about the future of our children and chidrens children, for them we owe to promise to keep our minds open and a determination to succeed and for them to live our dreams.

    ps - magnetic drives are the most sensible way forward. and in time, before it of course becomes pointless to measure time, it will take us beyond our suns own wind...

    Good luck to both voyagers, but I have no doubt in a couple of hundred years or so they will be home on Earth in a museum, collected and returned as a testiment to us who live now.

  • Comment number 77.

    if all the countries involved in space tecnology combined together thenit would be a lot sooner to get to the stars,international co operation is needed to succeed

  • Comment number 78.

    Before we can even think about such ventures, we will need the world to be at peace so we can divert the trillions of dollars currently spent on killing each other into more worthwhile causes.

    The diversity of cultures make this planet a more interesting place, but also means wars will always be present. This fact alone will prevent us from ever achieving our goals.

  • Comment number 79.

    I'll try to put this in laymans terms. It is not a matter of how fast a rocket can go, but rather, how small the space it travels through can be contracted. Why doesn't science think outside of the box? Furthermore, if all points of the Universe are connected, then surely science can actively use or exploit this, to assist man in exploration of it.

  • Comment number 80.

    Whatever ways are found, we must remember that it is not so much speed, but acceleration that might be the problem. Electric engines are fine, but they take a

  • Comment number 81.

    The human species is young, primitive and very violent. We are only just emerging as a species that can begin to understand where we came from. We will one day have to travel to new worlds to survive but this is many milenia off. Until then we will just have to dream but one day I beleive we will travel to the stars.

  • Comment number 82.

    I'm no big brain but if light travels as fast as it does, and this is a problem because e=mc thingy, infinite mass needed to accelerate a particle to light speed etc. How come when I turn on my lights I'm not crushed to nothing by the sudden weight of the photons hitting me. Cracking what makes a photon travel so fast without the weight must be the solution? Then it's an engineering problem, seating plans, armour, brakes, deflector shields, and lasers, got to have lasers, to shot the Aliens we find on our peaceful missions. Or have I read to many posts in the early hours without my glasses and I'm missing something?

    On a side note, I have always loved the idea of a space lift, and the "Warp" travel scares me.

  • Comment number 83.

    A few things to think about,there is much more to discover in physics.Look at the computing advances of the last 20 years alone. Some say we have not hered from ET yet but the message might arrive tomorrow or in 2000 years, 100 years after we wiped our selfs out! see my point. We are still very young. Timing as far as contact is concerned is everything. For us and any potential ET. As far as reaching the stars, if there is a will there will be a way. We just have to find it and then invent it.

  • Comment number 84.

    Some excellent posts on here.

    When you think about it, all these wars over religion, and obsession with finance are a terrible waste of resources. Can you image what could be achieved if we all pulled in the same direction!?

    While democracy is of course a necessity, it does also hold us back: ie. Each leader is so focussed on getting re-elected that no individual is looking at the greater good of humanity. Do the UN have a division for looking after the future of humanity? I don't know, but they should.


    As has been said, we need to expand. I don't think setting up life-sustaining structures on the moon and Mars are that far beyond the realms of possibility, lets start there. At least then we have a contingency should anything terrible happen to Earth. Buy ourselves more time to think about interstellar travel.

  • Comment number 85.

    relaxingrollup wrote:

    "if all the countries involved in space tecnology combined together thenit would be a lot sooner to get to the stars,international co operation is needed to succeed."

    No, "international cooperation is needed" for most to "succeed." It is quite clear that at least one country can do it on its own.

  • Comment number 86.

    love this topic!
    I want to throw into the mix the theory of the holographic universe.
    As we know all our senses are just chemical processes in our own brains. What we observe through our senses but the universe may not actually be as we “see” it. The great distances we observe and the current understanding of the speed of light is all just constraints or mind has put in place to explain what our senses are telling us.
    *In 1982 Alain Aspect performed and experiment which related to the EPR Experiment devised by Albert Einstein & colleagues. Apsect discovered that under certain circumstances subatomic particles such as electrons are able to instantaneously communicate with each other regardless of the distance separating them. It doesn’t matter if they are 10 feet or 10 billion miles apart.
    Somehow each particle always seems to know what the other is doing. This contradicts Einstein’s long held tenet that no communication can travel faster that the speed of light. University of London physicist David Bohm believes the reason subatomic particles are able to stay in contact with each other regardless of distance is because the distance is only an illusion and the particles are not miles apart. All things in the universe are infinitely interconnected.
    *http://www.crystalinks.com/holographic.html source.

  • Comment number 87.

    Expelling-mass propulsion will ever limit manned space exploration to our solar system. I believe phase-shifted electrodynamic propulsion will really unlock interstellar travel for mankind. http://tinyurl.com/nuclear-fusion-starship

  • Comment number 88.

    63 Sideliner wrote: "Interstellar travel is a dangerous fantasy because it encourages us to believe that we have other options if we trash this planet. We don't."

    No, Sideliner, the opposite. Interstellar travel is a progressive goal, because it encourages us to understand that our options will expand if we take care of this planet.

    "Interstellar travel is a dangerous fantasy" is the dangerous fantasy.

    Stephen
    Oxford

  • Comment number 89.

    Everyone is talking about speed and how quickly we could get there, however isn't it more feasable to become the true space traveller and live a whole life in space. I'm sure we are much closer to extending our life span then reaching or nearing the speed of light. Now I know we may be talking many genarations of life and death in space but this may be the only solution in the spread of human life beyond our planet. Again rather than sending a few people we may have to send hundreds if not thousands of people. The obsticles here are more realistic, in that how do we grow food, replace oxygen, create artifical gravity and electricity over 100's of years as well as how do we build something that large in space. Man has always strived to see what's over the next horizon, river or ocean space is just that next giant step in the process.

  • Comment number 90.

    There is also a train of thought that life started here on earth from an meteor or other piece of planetary debris ejected from a distant impact on another planet. As every living organism on earth is made from the same carbon makup, maybe we just need to blast thousand/millions small containers containing frozen bacteria off in every direction in space. There then might be just the slim chance that they arrive on a distant planet burst open and release there bacterial soup to allow life to start there.

  • Comment number 91.

    I think our only hope for near term interstellar travel is that someone like Burk Heim is proven right. Unfortuantly the people who could have tested his theory were more concern about damage to there precious machine than discovering a means of travel that could make inter solar and interstellar travel practical in our life times and if it fails then whole well at least it a other option tick of the list and we may find other paths of research to wonder down.

    The other options all seem like desperate gamble to me that we would only do if we found out that our solar system or the planet would become non-viable in a short while.. Robotic missions would be interesting especially if they took the von Neumann approach and made them self replicating, they could conceivable visit every star in the galaxy in under a hundred thousand years if they have the right propulsion system.

    I think a unmanned mission to a star could be done today, like a man mission to Mars could be done today if we wanted to, politicans and the general populous just do not want to.

    I just hope we will find a nice attractive target to aim for, perhaps knowing there a earth like planet out there with liquid oceans, oxygen, even signs of methane and other elements of life, and best of all if it is in a the goldley lock zone would that be enough to drive us on to build our first interstellar vessel. Of cause such a target to be truly tempting it would have to be less than 50 lights years away or a lot nearer.

  • Comment number 92.

    Interesting posts as usual.

    Seems to me it will be profit and need which will accelerate the technology. This happens with computers, TVs and other electronic gadgets because there is huge competition amongst large corporations for our pound or dollar. Once there is a real need or there is serious money to be had from space - mining, tourism or some such thing, then I don't believe that cost or technical difficulties will come in to it. Governments are just not very good at this sort of thing. I imagine schedules at NASA are not nearly as pressing as those at say, Apple when the latest ipod has to hit the streets for Christmas. So years go by and we move forward slowly with much less innovation then there would be if there were a dozen other outfits trying to do the same thing but sooner and for less money.

    This is starting to happen with several private companies now designing and building rockets but it is very early days. Imagine how quickly things will move when China finally uses up all the easily extracted raw materials it needs and starts getting them from the moon or the asteroids. Is America going to sit back and buy all its raw materials from China. No, those big oil and mining companies will be putting up the money needed to get up there and competing.

    And, once we're out in the solar system the rest will follow, we will spread slowly from system to system rather than making one dramatic eons long journey. We will need faster propulsion systems to do this but perhaps it doesn't need to be faster than light yet.

  • Comment number 93.

    The major obstacle we face in pursuit of space is the difficulty of escaping our own gravity well. In order to bootstrap a space industry/economy in our own solar system we need to get sufficient equipment and material into orbit to construct the infrastructure required to build it.

    Blasting small payloads into orbit on top of a half million gallon fuel tank is not the way forward, any launch platform that creates its own weather system can't be good for the health of the planet.

    Until we make some breakthroughs in our understanding of gravity and develop more efficient ways of overcoming it our time would be better spent investigating alternatives like the space elevator (read the science before crying fantasy).

    When we have a workable space based industry in place we can start taking some of the ideas for interstellar travel off the drawing board and begin putting them into action.

    Too many commentators on this post are eager to throw up the 'impossible to do' barrier. This is very negative and self defeating. Just because our current level of understanding holds us back right now doesn't mean it will tomorrow. Encourage the visionaries, don't berate them.

  • Comment number 94.

    I have been waiting what seems like an eternity for BBC Horizon to discuss this subject. I cant find a documentary anywhere, (and I've really looked) that talks about recent developments in interstellar space travel. Excluding that is, a few short passages on yes, VASMIR.

    I don't really expect we will be visiting any star other than our sun in my lifetime, but I would dearly love to know how it could be possible, given future advancements. But equally, how far we could get with current technology if money were no object.

    I just find it all very tantalising, very interesting.

  • Comment number 95.

    The science around why we cannot travel faster than light is pretty well understood, and with each step we take in understanding why we will never be able to do this, the more that of the rest of the reality (that science attempts to describe), makes sense. Trying to think of ways of going faster than light is an actual physical barrier to your being able to understand most of the rest of what modern science tries to tell you about the universe. Stop trying, and it all makes a lot more sense.

    It's not the journey, that is impossible: it's the arriving. you cannot collapse the wave form of the universe between any two pieces of reality faster than the speed of light. This means that it doesn't matter how you got there - if you got there faster than the speed of light would take you, you have collapsed your own wave form, that of your ship and the that of the entire universe around you, at a speed that is inconsistent with either you, the ship, or the entire universe being made of matter.

    It's fairly safe to say that it will never be possible for anyone, anywhere, ever, to undertake any journey, that would lead to them arriving at their destination at super-light speeds.

    Certainly, things like quantum entanglement are interesting, but it is important to recognise that what is happening is not 'communication'. the quantum particles were entangled before they began moving apart. Collapsing the way form of the one, infers that the other exists in the other wave form, but since you cannot communicate this fact to the person measuring the other particle at a speed faster than light, the other particle, and the person measuring it, do not, logically exist within your universe. You knew that a copy of the person measuring the inferred state MUST have been capable of existing in a future-projected universe, within which you had communicated your findings to each other, so in fact you learn nothing.

    If you try to explain any of this to Star Trek fans, however, they often become highly aggressive and accuse you of being 'stupid' for 'not being able to imagine beyond the bounds of modern science'. (Personally, I believe that being able to understand the problem from WITHIN the bounds of modern science, in the first place, is a fairly good starting point - but since I see no reason why I should dedicate my thoughts to understanding how 'dragons', 'unicorns', or 'mermaids' could exist, I feel disinclined, wasting my time trying to show why faster than light travel can exist, either.)

  • Comment number 96.

    I want to see fewer large spaceships and spaceprobes and more small - I mean tiny mini-probes or even nano-probes or bots. With the tech today surely it must be possible to build THOUSANDS of these - each with just one function or experimental capability.

    If each probe were the size of mobile phone (or smaller) a huge number could be simultaneously released to go to say, Mars. If we lose a few along the way the mission is never completely lost. And the software in each bot could be made to allow the unit to work independently, or to swarm with nearby bots, sharing data.

    I guess the issues will be power and transmission: how to build a power source inside an object the size of a phone that will last several years. And how such a tiny object could communicate data back to earth. Perhaps some specialised bots could configure themselves into the shape of a large parabolic antenna and relay data from the other swarm members.

  • Comment number 97.

    Someone may need to just clarify something for me:

    Is the current view that it is impossible to accelerate THROUGH the speed of light, or impossible to go faster than light full stop?

  • Comment number 98.

    History has shown us that as our understanding progresses then the things we want to achieve become possible. Who thought invisibility was impossible or teleportation and yet these ideas require a lateral view of the universe - clever thinkers. This situation is no different. We are at a place of infancy in our knowledge. To speed things up we need:

    1. to get stuff in space easier so as to develop space factories and techniques that avoid building things in earth gravity with a role for low gravity use (space)
    2. Energy understanding - the universe is filled with energy even in a vaccuum. Is it possible to harnass it much like sailors harness the wind? Or a plane harnasses the air for lift? Fusion reactors might be needed and commonplace
    3. A better understanding about gravity - Relativity explains how gravity works mathemtically just as Newton did 200 years before. Mass causes gravity by bending spacetime. If we could generate mass at will by generating Higgs bosons say then an interaction between big (Gravity) and small (quantum) will develop. Manipulating this effect may lead to speedy space travel

    This is all stuff in devleopment and a revolution is needed. Something small like the laser that has a massive impact on physics.

  • Comment number 99.

    > Is the current view that it is impossible to accelerate THROUGH the speed of light,
    >or impossible to go faster than light full stop?

    Well, the former is more definite than the latter. It's clear (and particle accelerators won't work if this weren't true) that pouring kinetic energy into a particle with rest mass won't ever get you to the speed of light. In fact, in terms of reaching the speed of light, 0.99999c isn't really "closer" to the speed of light than being stationary.

    The speed of light is like an infinitely high wall, and accelerating it like trying to climb it. The wise man, faced by an infinitely high wall, will try to find a way to cut a hole or tunnel underneath.

    But there are also serious problems with going faster than light (beyond how do you get there). Special relativity says, essentially, that any faster than light drive can also be used as a time machine (and, trivially, vice-versa). So you have to face up to the fundamental objections to time travel, the "grandfather paradox" in particular.

    If you are to survive FTL travel you'll need some kind of space/time pocket where normal physics operates. The theory of wormholes is the best known example. You enter a wormhole (the interface would presumably be spherical, not disc-shaped as they are always depicted cinematicly). The space/time inside the wormhole would have to seem fairly normal, but probably what you were using for time would be parallel to what an outside observer would consider a line through space, and probably one of the space dimensions would correspond to a space axis. Whatever the time that appeared to pass for the traveller, to outside observers he might emerge just before, or just after entering, or instantly. Different observers, moving at different velocities would see these different cases.

    My guess would be that the traveller would see the journey time more or less as if he were moving at the speed of light, so the subjective time would be a lot longer than the time as measured by an external observer. You might want to use biostasis here.

  • Comment number 100.

    Cheers for that Mr Chicken, interesting.

    So, with your last paragraph, what you're saying is that you think going through a wormhole would have the opposite effect to travelling at relativistic speeds, in terms of time dilation? I.e. the timespan is longer for the traveller, rather than the observer?

    Regardless of the problems with the workability of the idea, would some kind of space-stretching "warp drive" avoid the problem of the link to backwards time travel?

 

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