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Cosmic Loneliness and Interstellar Travel

Nick Nielsen’s latest invokes the thinking of Carl Sagan, who explored the possibilities of interstellar ramjets traveling at close to the speed of light in the 1960’s. What would the consequences be for the civilization that developed such technologies, and how would such starships affect their thinking about communicating with other intelligent species? Sagan’s speculations took humans not just to the galactic core but to M31, journeys made possible within a human lifetime by time dilation. Nielsen, an author and contributing analyst with strategic consulting firm Wikistrat, ponders how capabilities like that would change our views of culture and identity. Fast forward to the stars, after all, means you can’t go home again.

by Nick Nielsen

Nick-Nielsen

In my previous Centauri Dreams post, I discussed some of the possible explanations of what Paul Davies has called the “eerie silence” – the fact that we hear no signs of alien civilizations when we listen for them – in connection with existential risk. Could the eerie silence be a sign that older civilizations than ours have been risk averse to the point of plunging the galaxy into silence, perhaps even silencing others (making use of the Rezabek maneuver)? It is a question worth considering.

For one answer is that we are alone, or very nearly alone, in our galaxy, and probably also in our local cluster of galaxies, and perhaps also alone even in our local supercluster of galaxies. I think this may be the case partly due to the eerie silence when we listen, but also due to what may be called our cosmic loneliness. Not only are our efforts to listen for other intelligences greeted with silence, but also the attempts to demonstrate any alien visitation of our planet or our solar system have turned up nothing. When we listen, we hear only silence, and when we look, we find nothing.

The question, “Are we alone?” has come to take on a scientific poignancy that few other questions hold for us, and we ask this question because of our cosmic loneliness. We are beginning to understand the Copernican revolution not only on an intellectual level, but also on a visceral level, and for many who experience this visceral understanding the result is what psychoanalyst Viktor Frankl called the existential vacuum; the whole cosmos now appears as an existential vacuum devoid of meaning, and that is why we ask, “Are we alone?” We ask the question out of need.

nielsen_image1

Image credit: TM-1970, Russia (via Dark Roasted Blend).

While talk of alien visitation is usually dominated by discussions of UFOs (and merely by mentioning the theme I risk being dismissed as a crackpot), due to the delay involved in EM spectrum communications, it is at least arguable that communication is less likely than travel and visitation. That being said, I do not find any of the claimed accounts of extraterrestrial visitation to be credible, and I will not discuss them, but I will try to show why visitation is more likely than communication via electromagnetic means.

An organic life form having established an industrial-technological civilization on its homeworld – rational beings that we might think of as peer species – would, like us, have risen from biological deep time, possessing frail and fragile bodies as we do, subject to aging and deterioration. An advanced technological civilization could greatly extend the lives of organic beings, but how long such lives could be extended (without being fully transformed into non-organic beings, i.e., without becoming post-biological) is unknown at present.

For EM spectrum communications across galactic distances, even the most long-lived organic being would be limited in communications to only a small portion of its home galaxy. If civilizations are a rarity within the galaxy, the likelihood of living long enough to engage in even a single exchange is quite low. In fact, we can precisely map the possible sphere of communication of a being with a finite life span within our galaxy (or any given galaxy) based on the longevity of that life form. Even an extraordinarily long-lived and patient ETI would not wish to wait thousands of years between messages, especially in view of the quickening pace of civilization that comes about with the advent of telecommunications.

It could be argued that non-organic life forms take up where organic life forms leave off, and for machines to take over our civilization would mean that length of life becomes much less relevant, but the relative merits and desirability of mechanistic vs. organic bearers of industrial-technological civilization (not to speak of being bearers of consciousness) is a point that needs to be argued separately, so I will not enter into this at present. But whether ETI is biological or post-biological, no advanced intellect is going to send out a signal and wait a thousand years for a response, since in that same thousand year period it would be possible to invent the technologies that would allow for travel to the same object of your communication in a few years’ time (i.e, a few years in terms of elapsed shipboard time).

Our perfect ETI match as a peer civilization in the Milky Way will have already realized that electromagnetic communications mean waiting too long to talk to planetary systems that can be visited directly. If they are a hundred years ahead of us, they may already have started out and may find us soon. If they are a hundred years behind us, they will not yet even have the science to conceive of these possibilities as realizable technological aims. But what is the likelihood, in the universe in which intelligent life is rare (and we know by now that there are no “super-civilizations” nearby us in cosmic terms – cf. my Searching the Sky), that in all the vast space and time of the universe, a peer civilization should arise within a hundred years’ development of our own civilization? Not very likely.

The further we push out the temporal parameters of this observation, the more likely there is another civilization within these temporal parameters, but the further such a civilization is from being a peer civilization. Take a species a thousand years behind us or a thousand years ahead of us: the former cannot form a conception of the universe now known to observational cosmology; the latter will have technological abilities so far beyond ours (having had an industrial-technological civilization that has been in existence five times longer than ours) that we would not be in any sense their peer. And they would have already visited us. If we set the parameters of temporal radius from the present at ten thousand years, or a hundred thousand years, we are much more likely to find life on other worlds, but the further from our present level of development, the less likely any life found would be recognizable as a peer civilization.

How would we visit other worlds directly? With the breakthrough technology of a 1G starship (i.e., a starship than can accelerate or decelerate at a constant of one gravity) [2], all of the waiting to discover the universe and what lies beyond virtually disappears for those willing to make the journey. And while I have called this 1G starship a “breakthrough technology,” it is not likely to happen all at once in a breakthrough, but will probably take decades (if not centuries) of development. Our first interstellar probes, Voyager 1 and Voyager 2, are already headed to the stars [3]. It would take tens of thousands of years for the Voyager probes to arrive at another solar system, should they survive so long. Incremental improvements even in known propulsion technologies will yield gradually more efficient and effective interstellar travel (and will not require any violations of the laws of physics). While we don’t yet have full breakeven in inertial confinement fusion [4], we can in fact achieve inertial confinement fusion at an energy loss, meaning that an inertial confinement fusion starship drive is nearly within the capability of present technology. All of this leaves aside the possibility of breakthrough technologies that would be game-changers (such as the Alcubierre drive).

If we assume that a peer species would emerge from an Earth twin, we can assume that such a peer species would be subject to roughly similar gravitational limitations, so that an ETI 1G starship would be something similar in terms of velocity. Human beings or a peer ETI species, while unable to engage in any but the most limited EM spectrum communications over galactic distances, would find the galaxy opened up to them by a 1G starship, able to explore the farthest reaches of the universe within the ordinary biological lifetime of intelligent life forms even as we know such life forms today (i.e., ourselves), limited to a mere three score and ten, or maybe a bit more.

I have mentioned inertial confinement fusion above as a possible starship propulsion system, but this example is not necessary to my argument. If there existed only a single propulsion proposal for interstellar travel, and all our hopes for such travel rested on an unknown science and an unknown technology, we would have good reason to be skeptical that interstellar travel would ever be possible under any circumstances. This, however, is not the case. There are a wide variety of potential interstellar propulsion technologies, including inertial confinement fusion, matter-antimatter, quantum vacuum thrusters, and other even more exotic ideas. As long as industrial-technological civilization continues its development, some advanced propulsion idea is likely to prove successful, if only marginally so, but marginally will be enough for the first pioneers who are willing to sacrifice all for the chance at a new world.

It is humbling that we know so little about these technologies and the science that underlies them that we are not today in a position to say which among these might prove to be robust and durable drives for a starship, but the very fact that we know so little implies that we have much to learn and we cannot yet exclude any of these exotic starship drive possibilities, much less dismiss them as impossible. While no one has yet produced a proof of concept of any of these proposed forms of propulsion, it is also the case that no one has yet falsified the science upon which they are based.

Even the most successful of the drives mentioned above (with the exception of the Alcubierre drive) will involve time dilation as a condition of interstellar travel. There has been a tendency to view time dilation as a cosmic “fun spoiler” that prevents us seeing the universe on our own terms, since the elapsed time on one’s home world means that no one can return to the world that they left. We need to get beyond this limiting idea and come to see time dilation as a resource that will allow us to travel throughout the galaxy. It is true that time dilation is a limitation, but it is also an opportunity. As Carl Sagan noted:

“Relativity does set limits on what humans can ultimately do. But the universe is not required to be in perfect harmony with human ambition. Special relativity removes from our grasp one way of reaching the stars, the ship that can go faster than light. Tantalizingly, it suggests another and quite unexpected method.” [5]

Human ambition, as Sagan suggests, wants interstellar travel without the price exacted by time dilation, but the universe is not going to accommodate this particular ambition. We have had to reconcile ourselves with the fact that historical transmission is a unidirectional process. We can read Shakespeare, but we cannot talk to Shakespeare. Shakespeare’s contemporary Queen Elizabeth could make it known that she wanted to see Falstaff in love, and “The Merry Wives of Windsor” resulted, but we cannot approach the Bard to write the perfect comedy of manners in which smart phones and text messages figure in the plot.

Just so, we are all unidirectional time travelers, and the eventual development of travel at relativistic velocities will not give us the ability to travel backward in time, nor will it allow us to travel to the stars without giving thought to the inertial frame of reference of our homeworld, but it will give us more alternatives for going forward in time. We will have the opportunity to choose between an inertial framework at rest (presumably relative to our homeworld), and some accelerated inertial framework in which time passes more slowly, allowing us to travel farther and, incidentally, to see more of the universe. Even if we can never go back, we can always go forward. Relativistic interstellar travel will mean that we have a choice as to how rapidly we move forward in time. The possibility of always going farther forward in time has consequences for existential risk mitigation that I will discuss in my next Centauri Dreams post.

Notes

[1] Cf. Viktor Frankl, Man’s Search for Meaning

[2] Carl Sagan discussed the 1G starship in his Cosmos, Chapter VIII, “Travels in Space and Time”; I quote from this same chapter below.

[3] As of this writing, Voyager 1 has passed into interstellar space, while Voyager 2 has not yet emerged from the heliosheath and into interstellar space.

[4] A near breakeven in inertial confinement fusion was recently achieved, in which produced more energy that was absorbed by the fuel for the reaction, but this is not the same as producing as much energy from the fusion reaction as was pumped into the lasers making the reaction happen. (Cf. Nuclear fusion milestone passed at US lab.)

[5] Carl Sagan, Cosmos, Chapter VIII, “Travels in Space and Time” (cf. note [2] above)

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Comments on this entry are closed.

  • Tarmen December 6, 2013, 10:17

    This line of reasoning makes me think that beings or machines created in a ET civilization of a era long long since died out at its origin – will nevertheless find themselves flitting into our time. So, there are many more opportunities to encounter artifacts or living representatives of ‘dead’ civilizations than we might suppose. A long lived machine being , let’s say 10,000 year warranty , might travel through a million years into its future and discover us in our present. And if it can self repair….. then it could have been ‘born’ much much longer than a million years ago.

  • M Mahin December 6, 2013, 10:34

    I find your reasoning unpersuasive.

    “No advanced intellect is going to send out a signal and wait a thousand years for a response, since in that same thousand year period it would be possible to invent the technologies that would allow for travel to the same object of your communication in a few years’ time (i.e, a few years in terms of elapsed shipboard time).” Wrong, wrong, wrong. You’re totally overlooking the fact that space travel near the speed of light would be insanely more expensive than radio communication, plus there is every reason to doubt that any spaceship that could possibly be built could travel at close to the speed of light (practical engineering constraints; we’ll be lucky if we ever get 25% lightspeed).

    “We know by now that there are no “super-civilizations” nearby us in cosmic terms” — no we don’t know any such thing. We don’t know to what degree a supercivilization would engage in mega-engineering that would be visible to us.

    See my post “The Rare Colonization Hypothesis” at The Rare Colonization Hypothesis
    for an alternative viewpoint. There are strong reasons for thinking that interstellar colonization should be fairly rare. They should not at all be here already.

  • ljk December 6, 2013, 10:47

    The Cosmos episode mentioned in this article is online for free from Hulu here:

    http://www.hulu.com/watch/63323

  • Rev. Richard Prichard December 6, 2013, 11:11

    I thought a game stopper for any type of relativistic rocket propulsion is hitting space debris. Even if you are only going 10 percent of the speed of light, you would be encountering constant energetic collisions.

  • Paul Gilster December 6, 2013, 11:22

    M Mahin writes:

    See my post “The Rare Colonization Hypothesis” at The Rare Colonization Hypothesis for an alternative viewpoint. There are strong reasons for thinking that interstellar colonization should be fairly rare. They should not at all be here already.

    Mark, good post, and I’ve added your site to our links. If you would, though, give us a quick rundown of your alternative viewpoint in the comments here — i.e., a few bullet points, etc., for those who may not follow the link. Sagan, and Nick Nielsen, were speculating about 1G starships, for example, but you put the velocity limit for interstellar at a small percentage of c, which does indeed take the discussion in a different direction.

  • David Cummings December 6, 2013, 11:49

    Nick, excellent post. I enjoyed reading it very much.

    In my opinion, major increases in human lifespan will probably progress at least as fast as major breakthroughs in close-to-lightspeed travel.

    And in a sense, the two will enhance each other. Travelers experiencing time dilation will be much less threatened by the “changing world at home” if their friends and family who stay behind are “beyond aging” themselves, even though they remain in the “speeded up” frame of reference.

  • David Cummings December 6, 2013, 11:52

    Rev. Richard Prichard December 6, 2013 at 11:11
    I thought a game stopper for any type of relativistic rocket propulsion is hitting space debris.

    To me they are aspects of the same problem. How do you get to 10% (or 90%) of the speed of light? That question has two parts, part 1 involving propulsion, part 2 involving protection. I think the solutions to those two separate parts of the problem will proceed apace with each other.

  • James D. Stilwell December 6, 2013, 12:02

    A thought provoking post…
    Alchemy beget chemistry…
    Biology beget High Intelligence…
    Genius beget Centauri Dreams…
    No question about it at all…

  • Paul Gilster December 6, 2013, 12:09

    James, a very kind thought, sir. Many thanks!

  • ljk December 6, 2013, 12:13

    The BIS Daedalus probe used a “dust bug” Warden about 100 miles ahead of the interstellar vessel which would spray dust to encounter any debris and vaporize it via impact before it could reach the probe.

    Or how about a giant block of ice as a dust shield in front of a star probe?

  • Rob Flores December 6, 2013, 12:53

    Maybe the probability of contacting and communicating with someone
    across the galaxy is out. But within 5,000 LY it just might be feasable
    to do just that with only Local solar system space tech/capacities, while
    simultaneously increasing the likelyhood of encountering “peer” civs.

    You could set up a “contact” voice in deep time.
    That is create the tech to allow a few hundred people to timeshare the
    empty period between communications/attempts at communications.
    In this setup 99% of your contact crew is asleep at any one time, and a few awakened for 3 years time. this cohort would not be awakened for another 100 years.

    Obcourse this contact group should be isolated from the main civilization
    simply for their safety. Maths from Anathema come to mind. Would you be willing to live out your life this way? If the tech were safe and no memories or experiences were diminished? why not.

  • Edg Duveyoung December 6, 2013, 14:06

    With all the planets we’ve discovered so far being within 21,000 light years, if any of them had ETI, they’d know Earth was filled to the brim with biological processes if they could get Earth’s light seen separately from the Sun’s. And they’d be almost certainly thousands if not millions of years more advanced than us, so more likely than not, they’ve got the resolving power to read our cars’ license plates.

    If any of them saw Earth so long ago without any tech impurities showing signs of Earthly civilization, AND

  • Edg Duveyoung December 6, 2013, 14:18

    AND, if they knew there WOULD be tech-life eventually, they might have sent messages to us knowing that by the time we could receive them, the messages would be arriving right on time!

    What would we do if we saw an earthlike planet with no tech signature?

    Meanwhile, to me the great silence is due to “the great gulf between advanced and not-advanced tech.”

    We know the porpoises and other animals have very rich social and psychological lives, yet we have almost zero attempts to find ways to “connect with them” in some manner. So I ask: are ETIs, when it comes to “why to bother with trying to establish contact with Earthlings” coming up with similar lack of interest in a lesser species?

    “How advanced?” become the question for me. Even a thousand years more advanced and the tech would probably have them able to comfortably examine us to the nth degree without leaving their worlds. All such “couch potato” civilizations would, of course, not know about our tech for thousands of years hence when our radiation arrives there, so they’d all be enjoying “Earth Reality Shows” — featuring dinosaurs more likely than not.

    For those who can fold space and “get there now,” again, they’re so advanced that we’re just not interesting-as-peers.

    If we do get to where we, too, can fold space, THEN we’ll see if we attract any visitors when they see that we can move in next door to them and marry their sisters.

  • DCM December 6, 2013, 15:05

    Our main emphasis for now should be making use of our immediate surroundings — the existing solar system and artificial worlds we might build — though we shouldn’t lose sight of interstellar goals.
    Colonizing and terraforming will occupy us for centuries even if science continues to be refined.

  • Alex Tolley December 6, 2013, 15:09

    For EM spectrum communications across galactic distances, even the most long-lived organic being would be limited in communications to only a small portion of its home galaxy. If civilizations are a rarity within the galaxy, the likelihood of living long enough to engage in even a single exchange is quite low. In fact, we can precisely map the possible sphere of communication of a being with a finite life span within our galaxy (or any given galaxy) based on the longevity of that life form.

    Why is an individual’s lifespan important? Institutions, e.g. religious ones, can wait through many generations for an answer. In extremis we have Douglas Adam’s waiting for a very long time for Deep Thought’s answer to the meaning of the universe and then subsequently waiting for the question to the answer 42. I’ve no doubt that the Vatican would happily wait a millennium for an a answer from God.

    The other reason that physical presence may be inferior to EM communication is the cost to locate another species. It is much cheaper to target many stars concurrently with signals than to send out even one ship that then has to search many systems for peer civs to communicate with.

    While you are happy to posit possible FTL drives (Alcubierre) , you ignore possible FTL communication that would negate its advantage. If FTL communication is possible, what better way to operate than place receiver/transmitters in all likely systems to await discovery of advanced civs (A Monolith variant). Perhaps we should look more carefully for one?

    While it is fun to speculate, the answers or prejudices we have impacts our thoughts on SETI, METI and colonization. What we need is data on whether life, especially advanced life, let alone civs are out there. If we are seriously talking starships within a few centuries, then we will need answers to the life question before we send out the ships. To my mind, the fastest solution is telescopic, followed by extremely small, fast probes to suspected living worlds. If we find pre-technical species that could develop, we would want to leave sensors to alert us to their development.

  • David W December 6, 2013, 15:26

    Edg You got me thinking We have tons of studies that show Dogs know us very well and understand our words -Communication may be our problem We tend not to listen to them
    http://wqad.com/2013/12/05/video-shows-puppy-being-dragged-behind-motorized-scooter/

    I would add we do have proof of concept on matter-anti-matter BUT we don’t know how to make enough anti matter ( BTW Roddenberry thought we would by the 90s when he planned Star Trek) Also we would be able to communicate and return to say AC and nearby stars in a lifetime . I am not a transhumanist I think we have limits but I could see 200 years and maybe longer if we could alter embryos . I guess I am optimistic on these technologies but not a super optimist . I am not so optimistic on human nature So maybe I buy the Cosmic Isolation ….or there are very civilizations or we are stuck in the world we got not what we want

  • Nick Nielsen December 6, 2013, 16:01

    @Tarmen

    I agree that relics of a civilization long past may flit into our present, but it must also be observed that there is a boundary in time earlier than which there can be no industrial-technological civilization, because through nucleosynthesis the universe produces more heavier elements as it develops. We won’t be seeing any high technology civilizations originating from population III stars of the early universe, and not likely from low metallicity population II stars. Admittedly, these spans of time are comparatively vast compared to the time scale of human civilization, but the fact of a boundary in the past for the emergence of an industrial-technological civilization gives us at least one constraint for speculating on what may have preceded us in the universe.

    Best wishes,

    Nick

  • Nick Nielsen December 6, 2013, 16:14

    @David Cummings

    Glad you found it to be of interest.

    Your comment is exactly what I had in mind, both that advances in life sciences and alternatives in temporal frames of reference will give us choices in the future for our temporal frame of reference that we do not have today. We have come to think of time as we experience it today and in the past as necessary and inevitable features of any human life. This is not likely to remain the case.

    It is interesting to note how thinkers like Marx and Oswald Spengler (and, to a lesser extent, Toynbee) focused on inevitable historical processes as a way to understand the large scale structure of human history. Isaiah Berlin powerful criticized this theme of inevitability. I’m with Berlin on this. What we see with the development of civilization and technology is the widening of opportunities and the narrowing of constraints, leading to fewer inevitabilities as time passes, not a consolidation of the inevitable that will result in some perfect utopian society or some horrific dystopia (i.e., flawed realization).

    Best wishes,

    Nick

  • Digbijoy December 6, 2013, 20:14

    It is ironical that in all such discussions of near light-speed travel, physicists and engineers tend to overlook the biological side :)
    Are we sure human biology will function the same (even in hitherto undemonstrated ‘hibernation mode’ for humans) in the same way when it is made to cruise at near-c speeds ? The body metabolism, the working of sensory organs, the nerve cells, cells functioning, heart beat, digestion, blood flow – will they not be affected at near-c speed levels ? I am just curious.

    However, if we speak of post-biological era where humans are immortal i.e. by transferring or downloading the consciousness & memory in to a machine/chip/computer, then biological limitations are eliminated. But to my understanding, there is no consensus among experts if downloading/transferring memory & consciousness of humans in to computer chips/robots is possible. Because, as soon as you stop blood flow and oxygen to the human brain for more than a few mins, the game is done – no transfer of consciousness is possible (with present biology/technology).

  • Nick Nielsen December 6, 2013, 21:03

    @Rob Flores

    A deep time contact voice would make an interesting project, and, yes, I do think that there would be a few people (enough) who would be interested in quite literally devoting their lives to this project. This may be the only way that human beings are able to contact ETI.

    Another angle on this is that, in the coming age of technological unemployment, a long term project like this that gives individuals meaningful work to do and something to which they can devote their lives (even if it doesn’t seem to make much economic sense in the present economic climate) may prove to be very attractive and there may be no difficulty in getting people to participate, even if it means losing regular contact with the main stream of civilization.

    It would be interesting to mathematically model several differently structured METI efforts and determine, within the parameters of our present knowledge, the likelihood that any one of these is more likely than another to be effective. Then the METI debate would have fresh relevance.

    However (and this is a big “however”), the length of time involved in this project would be so great that the main steam of civilization would go on to development a wide range of technologies that may make this effort obsolete — though maybe not. If the mainstream of civilization experiences permanent stagnation or flawed realization, an isolated outpost for a deep time contact voice could represent sufficient redundancy and autonomy to secure some degree of existential risk mitigation. And that’s all in addition to the possibility of first contact.

    Best wishes,

    Nick

  • Eniac December 6, 2013, 23:58

    I am not totally comfortable with the much-held assumption that longevity leads to greater patience. On second thought, I think it is almost completely false.

  • Eniac December 7, 2013, 0:17

    In addition to longevity, augmentation or uploading can also increase the speed of thought, which would have the opposite effect on patience.

  • Eniac December 7, 2013, 0:26

    M Mahin: The “Rare Colonization Hypothesis” assumes that a multi-world civilization can make and enforce a collective decision to slow down or stop colonization efforts. This is a fallacy. Any colony, especially interstellar ones, will quickly achieve independence and eventually proceed with colonization efforts of their own. The distant existence of the Old World and its other colonies (potential competitors), as well as its own history of successful colonization are more likely to speed up a civilization’s effort than slow it down.

  • Eniac December 7, 2013, 0:33

    Note that colonization on Earth has proceeded until every useable square inch of land is now accounted for and belongs to one of the nation states, with some still being claimed by several. Colonization went out of fashion only because there is nothing left to colonize.

  • Max Kalininskij December 7, 2013, 6:36

    As others have pointed out, you make too many assumptions in your reasoning, chiefly about the motivations of aliens (visiting our world, attempting communication, or showing any interest in it at all).

    As you have mentioned, the chances of us finding a ‘peer’ alien civilisation are not very likely.
    But in fact this is a huge understatement – to me it appears that the chances of us finding a peer civilisation anywhere in this galaxy or the next few over – are pretty much negligable.
    You increase the figures by a couple of orders of magnitude; 100; 1000 ; 10,000 – but even these time-frames seem incredibly unlikely. Compare how long our civilisation has had interstellar communications means for (100 years), to how long our species has been around at all (50,000-100,000 years), to how long life existed on our planet (3.5 billion years), to the entire age of the universe (+14 billion years).

    We have no idea how long it will take for intelligent life to evolve on an alien world and for it to produce tech capable of receiving and transmitting electromagnetic waves. But if we go by our own world; it’s taken 3.5 billion years since the first advent of life – on an alien world it can take anywhere up to that, or any number of years more. When faced with such time-frames, we are more likely to end up with differences in the hundreds of millions of years; with maybe a ‘mere’ million years difference between our civilisation and another – being counted as a very, very, close ‘peer’ match. Finding anything closer than that anywhere near us, will have the same probability as winning the galactic lottery.

    And if we take into account the different time-frames of planet and star system formation (there have been several generations/cycles before our current one); then the likely difference increases by yet another magnitude.

    Well it pretty much goes without saying that a life-form a million years behind ours will not be of much interest to us in terms of establishing civilisational contact, and one a million years ahead will not have much interest in us for the same reasons.
    That’s not to say there will be no interest, it’s just that this interest is not likely to manifest itself in any attempts at communication, or even making the foreign lifeforms aware of your presence.

    In terms of communications; well luckily million-years-ahead-of-us advanced aliens would likely have had the time to think of a few extra options other than electromagnetic waves and directly visiting our planet. For example, maybe send a probe with a faster than light drive that will arrive in our solar system and start communicating with us directly via our level of technology – radio waves and so on. Maybe such a probe is already here, and is lying dormant until they want something from us, or want to warn us about something. Any number of possibilities really.

  • Brett Bellmore December 7, 2013, 9:19

    Does anybody have a really good idea of the actual density and power law for solid particles in interstellar space? I think it likely that an interstellar ship wouldn’t have to deal with anything larger than a grain of sand on stuff. (Added by Victor)

  • Brett Bellmore December 7, 2013, 11:18

    Five year old at the computer again, while I left it for a moment. I think it likely that an interstellar ship wouldn’t have to deal with anything larger than a grain of sand. For this, you could maintain a light sail ahead of the ship, any particles that encountered it would be blown to ionized gas, while only making a tiny pinhole in the sail. Then you use a magnetic shield around the ship to deflect charged particles.

    The system would do nothing to protect you from anything as big as a piece of gravel, but, objectively, what are the odds of striking anything larger than a grain of sand on a 10 light year journey? Serious question, I don’t know. But their should be estimates.

  • Wojciech J December 7, 2013, 11:22

    David Cummings-I remember discussions about protection, and I believe somebody calculated that the highest speed that known materials could withstand is around 20% of c.

    Edg Duveyoung-you are spot on. Any civilizations thousands of years ahead of us, would already know about existence of our biosphere and civilization simply by telescopic observations. Direct attempts to communicate are unnecessary as our natural emissions do it for us since life started. And like mentioned in other posts, city lights are visible since 19th century at least if not much earlier(Rome for example was probably visible as well, and cities in Arab Empire where street lamps existed in 1000 AD in Cordoba or Baghdad ).
    So the answer is that they either don’t exist, are unwilling to or unable to communicate with us.

    “but also the attempts to demonstrate any alien visitation of our planet or our solar system have turned up nothing. When we listen, we hear only silence, and when we look, we find nothing.”
    We have seen only a small part of Solar System. If there is a probe the size of a Nimitz air carrier beyond Eris it wouldn’t be visible to us anyway.We don’t even know the entire subsurface of Earth’s oceans, neither we know the either solar system,
    As to looking-with the coming of new telescopes, we probably will know answer at least to the question if life exists beyond our planet within 20-50 years or so.

  • Steve Muise December 7, 2013, 12:33

    Personal, face-to-face contact has one huge advantage over interstellar radio communication between civilizations : a much larger bandwidth over a given period of time as well as much shorter latency.

    I’d hate to waste a 1000-year latency in communications having to ask “Can you say that again? I don’t understand what you meant.”

    In person communication allows for a much richer communication over a shorter period of time. I could see a Benford beacon / signal carrying the single message of “Come here. Follow this protocol and we’ll talk.”

  • Wojciech J December 7, 2013, 12:38

    “Eniac December 7, 2013 at 0:33
    Note that colonization on Earth has proceeded until every useable square inch of land is now accounted for and belongs to one of the nation states, with some still being claimed by several. Colonization went out of fashion only because there is nothing left to colonize”
    Completely wrong. States have willingly withdrawn from colonizing Antarctica for example, there are a lot of other places where humans decided to retreat leaving them alone:
    http://en.wikipedia.org/wiki/Desert_island

    There are also native peoples which are left alone and governments decided not to introduce them into modern society
    http://en.wikipedia.org/wiki/Sentinelese_people

  • NS December 7, 2013, 14:47

    If (as seems most likely) our consciousness is tied to our physical brains, uploading our mental contents into machines won’t make us immortal. At very best it might create mental clones of ourselves which will go on with their existence while we remain in ours. Not at all sure that either we or the machines would be happy with that…

  • Eniac December 7, 2013, 15:04

    Sorry, but under current laws of physics there can be no 1G space travel as you imagine. This is on account of the interstellar medium.

    I agree with Brett that solid particles may well be too rare to have to consider, although I am not sure anyone really knows.

    However, we do know the density of gas (overwhelmingly neutral hydrogen in our vicinity), and it is not hard to calculate the energy it would deposit impacting onto an object moving at a certain speed. As I recall, assuming radiative cooling, it would get too hot for even the hardiest materials at around 0.3-0.5 c. As you try to go even faster, it quickly gets worse, proportionally to the square of velocity. In addition, there is radiation damage, as this same gas would amount to hard ionizing radiation at relativistic speed.

  • James Antell December 7, 2013, 15:19

    Interesting posts, I look forward to the next. But at the risk of sounding naive or just plain stupid, I do hope we’ll get a more thorough explanation of time dilation. Here’s a snippet repeated:

    “Human beings or a peer ETI species, while unable to engage in any but the most limited EM spectrum communications over galactic distances, would find the galaxy opened up to them by a 1G starship, able to explore the farthest reaches of the universe within the ordinary biological lifetime of intelligent life forms even as we know such life forms today (i.e., ourselves), limited to a mere three score and ten, or maybe a bit more.”

    “… able to explore …” Really?

    I guess my question relates to the experience of the starship crew. If indeed they will travel throughout the entire galaxy (and even “to infinity and beyond” as a famous nonperson once said), then what is their internal experience of all this? Would they not necessarily have to perceive themselves as traveling at stupendous Star Trek speeds? Would it be possible for them to existentially experience (for example) a passage through the Aldebaran system as a leisurely sub-lightspeed jog or would it be more like, “Oh look there’s Aldeba … oh nevermind it’s gone.” But if they did perceive their own journey in sub-lightspeed terms, how could they possibly prevent themselves from going stark raving mad?

    If the crew played chess every day, would they play 70 x 365 games during their 70 year journey or would they play umpteen infinizillion games? What would happen during a single game? Would they perceive themselves to have made very little progress toward the next star — or would they fly by dozens of stars?

    If we on earth could imagine their existence, would it seem to us as though it took them many years to finish breakfast?

    I have a very difficult time imagining what the experience of the crew would be. If any species has such starships flying around out there, I imagine they would be nothing but spaceborne madhouses going nowhere and “exploring” nothing.

    I hope the next post addresses these issues.

  • Astronist December 7, 2013, 16:59

    James Antell, what the quote means is that an interstellar crew would be able to reach any specific target within our own galaxy or even beyond within a single human lifetime, if they could accelerate continuously for half the time at 1 gee, and then decelerate for the other half of the time at minus 1 gee, bringing them to rest at the destination. Obviously, if they then wanted to explore a second location, they would have to make another journey of this type.

    However, Nick Nielsen has no evidence, so far as I know, that such a drive is physically possible.

    If a starship makes a journey at a constant speed of 0.99c which lasts 70 years ship time, then 496 years will pass on any unaccelerated body such as Earth. There is no reason for this to upset the crew, since they will presumably understand relativity mechanics. (For a ship in constant acceleration, the calculation is more difficult.)

    Stephen A.

  • Nick Nielsen December 7, 2013, 19:03

    @James Antell
    @Astronist

    As Astronist notes, crew members can make at least one journey to any point within our galaxy, or even to nearby galaxies, within a lifetime at .9 G, accelerating half way and decelerating half way. If life science technologies continue their trajectory of development (as must happen in an industrial technological civilization; cf. below what I write about propulsion systems), longer life spans or some kind of hibernation will allow for longer journeys or multiple journeys.

    Regarding James Antell’s concern about shipboard life, I imagine that the experience of a starship crew would be not unlike the crew of any large self-contained community, like an aircraft carrier. However, I assume that there will also be non-military interstellar missions in which crew interaction will not be anything like shipboard life on an aircraft carrier. It would be easy to write a longish post just about this. I would also suggest consideration of Heath Rezabek’s research into Vessel Archives as another model of a community appropriate to life on a starship (which is, in a sense, an archive of Earth being sent to another star).

    Astronist writes that I have, “no evidence, so far as I know, that such a drive is physically possible.” One G acceleration is physically possible, which we know from chemical rockets that can accelerate at well over 1 G. What we do not know is whether a 1 G acceleration can be sustained over an extended period of time. I consider this an engineering problem rather than a physics problem.

    I wrote the above assuming that the constantly advancing technology of our industrial-technological civilization will continue to solve engineering problems, as long as they are consistent with physics (i.e., not physically impossible). If this civilization fails (i.e., if it succumbs to existential risk) then we won’t be doing any interstellar exploration at all (except for the Voyager probes, which will continue to coast through interstellar space), but if this civilization continues, we cannot have an industrial-technological civilization without new technologies, even if we cannot say what these technologies will be. (It is interesting to note that, logically speaking, this is a non-constructive claim.) This is the point at which it becomes important that we do not yet know what technologies, among the many under consideration, will prove to furnish a robust interstellar drive (or the power source that can power a starship for decades, though we might have that already, as an ordinary fission reactor on a submarine can operate for about 30 years).

    Best wishes,

    Nick

  • Nick Nielsen December 7, 2013, 19:19

    @Eniac

    “…under current laws of physics there can be no 1G space travel as you imagine. This is on account of the interstellar medium.”

    The interstellar medium is a constraint upon the velocity of a starship passing through it, but this is not the same as a physical impossibility. Relativity tells us why it is not possible for a starship to travel at the velocity of light. That is a physical impossibility. The laws of physics do not allow for this. However, the laws of physics do not specify anything about contingent circumstances about the interstellar medium. It is also important to note that the interstellar medium differs among regions. If one moved up and out of the galactic plane, there would be much less matter with which to contend.

    Many scientists and engineers have proposed ingenious solutions to the practical problems posed by traveling at high suboptical velocities in interstellar space. I assume that as long as our civilization continues, that new ideas and new technologies will continue to grapple with these problems. We will learn a lot about such things as we travel in our own solar system or send a probe out to the Oort cloud or the focal point of the sun at 550 AU. Practical experience and technological innovation will come together in unexpected ways to offer unexpected solutions, none of which will be perfect, but many of which will be practicable to some extent. These some considerations hold for materials technology, for power systems, for propulsion systems, and for life sciences.

    Best wishes,

    Nick

  • David OHara December 7, 2013, 20:42

    I see no issue of silence nor do I see any Fermi Paradox. The lack of nearby civilizations seems very likely if you do the following exercise.

    Write your own version of the Drake equation putting in the number of stars in the galaxy, the fraction having planets (most of em), the fraction having habitable to simplelife planets, the fraction that develop multicellular life, ,the fraction developing intelligence, technology, etc. You get a huge number of civilizations BUT, then you realize they are not all present at the same time.

    So, make an assumption of the age of a civilization before it “vanishes” from the view of others less developed (bear with me on this). Put in almost any reasonable number of years even up to several million and the density of civilizations available to contact drops radically. When I do this, I get an average distance between civilizations of hundreds of light years.
    Consider that our earliest radio messages have only gone about 73 light years and they are of so low power at that distance as to be below background noise.
    An ancient civilization has no reason to pay any attention to us. They already have data on millions of other civilizations in the past. For them to pay attention to us would be like expecting me to want to examine one more grain of sand after already having looked at millions. Data on one more grain is insignificant.
    If somehow a civilization manages to get FTL then they are even less likely to visit us because then the entire universe is open to them via time dilation and time reversal. We become REALLY insignificant to them then.
    So, why would a civilization become “invisible”? Safety for one, primitives are dangerous. Secondly because it may be very efficient that way. If one can encode one’s existence into the subatomic structure as a sort of algorithm, you could hide in plain sight and support more individuals than on a physical world.

  • Peter Chapin December 7, 2013, 21:14

    When it comes to contemplating communication over thousands of light years, it seems important to not forget pipelining. While it might take generations to get an answer to a specific question, both communicating peers could still send a steady stream of information more or less continuously.

    We could answer questions posed by our counterparts centuries ago, and pose our own questions for which we wouldn’t receive answers until centuries later. In addition both sides could add “random” information to the stream that each thinks will interest the other. It would take a long time to establish the flow but once done we would get fresh information about an alien culture on a daily basis. Perhaps we could even watch their TV shows (produced a thousand years ago)!

  • ThreefoldBurly December 7, 2013, 22:09

    Astronist: they would gain a lot of mass though, right? Also I have a hard time seeing all of this as any kind of solace. Exploration is about transferring information. And all the information explored this way would remain isolated within the explorers’ time frame rendering any talk of ‘exploration’ devoid of any tangible meaning.

  • Markham December 8, 2013, 0:38

    This paper poses an interesting twist on when the universe became conducive to life. Keep in mind there were early stars that exploded producing the heavier elements, if a free floating planet managed to avoid being irradiated life could have started quite a bit earlier in the universe…

    What this says about the Fermi Paradox is unclear as an ETI with this early of a start should have covered the Universe..

    Or it could leave us as the “outliers”, coming to intelligence long after the peak of fecundity… everyone else has died out.

    http://arxiv.org/abs/1312.0613
    The Habitable Epoch of the Early Universe
    In the redshift range 100<(1+z)<110, the cosmic microwave background (CMB) had a temperature of 273-300K (0-30 degrees Celsius), allowing early rocky planets (if any existed) to have liquid water chemistry on their surface and be habitable, irrespective of their distance from a star. In the standard LCDM cosmology, the first star-forming halos within our Hubble volume started collapsing at these redshifts, allowing the chemistry of life to possibly begin when the Universe was merely 15 million years old. The possibility of life starting when the average matter density was a million times bigger than it is today argues against the anthropic explanation for the low value of the cosmological constant.

  • coacervate December 8, 2013, 6:28

    I would ask that you post a “50 years of SETI” compendium so we can better understand this comprehensive body of work that leads so many to conclude…SILENCE! Not to be overly negative, but I don’t think you will find it. Ozma? WOW? Phoenix? Hat Creek? Baby steps. I don’t think we have made anything like a systematic survey for the detection of narrow band microwave or optical wavelength signals. One possible exception: SETIatHome, who report little but many hits. Considering the current disdain for science among USAmericans, I can’t see anything tangible in the works. I wonder if the Chinese zeal for knowledge and space science extends into SETI? Thus, my search continues “on this most unbright cinder”…not to be overly negative, mind you.

  • Brett Bellmore December 8, 2013, 8:59

    “As I recall, assuming radiative cooling, it would get too hot for even the hardiest materials at around 0.3-0.5 c. ”

    I think a dirty plasma, maintained in front of the ship by magnetic fields, could be much hardier than any solid material. The real issue, IMO, is the need to carry fuel to overcome drag.

  • Tarmen December 8, 2013, 14:32

    There had been a lot of water under the bridge before we came along. Many times in our past we thought that everything revolved around us. I believe it likely that this wilderness has long since been divied up into territories by the biggest badest old bears. They’re out there. But with a nose only for their rivals or their food, their energy souces. Those ‘old bears’ are probably AI machine networks. I know it’s depressing and most people don’t want the Earth to revolve around the Sun or humans to evolve from apes. But there it is. We can still carve out a niche.

  • Tarmen December 8, 2013, 14:51

    There had been a lot of water under the bridge before we came along. Many times in our past we thought that everything revolved around us. I believe it likely that this wilderness has long since been divied up into territories by the biggest badest old bears. They’re out there. But with a nose only for their rivals or their food, their energy sources. Those ‘old bears’ are probably AI with vast machine networks. I know it’s depressing and most people don’t want the Earth to revolve around the Sun or humans to evolve from apes. But there it is. We can still carve out a niche.

  • Robert McGown December 8, 2013, 18:31

    I really enjoy Nick’s Nielsen’s creativity and tying into Carl Sagan’s ideas on interstellar flight. If Carl were still alive he would be posting monthly and very active in these endeavours. Each expedition to the stars that we send out is like the oceanic voyage dispatches of Henry the Navigator. The Pioneer and Voyager mission venturing into deep space is like Vasco de Gamma and Bartholomew Diez expeditions sailing around Cape Horn. As sailing technology changed and steam ships explored and traveled across the oceans, we look to the breakthroughs of the 1G star ship will bring as well as and other advanced methods of propulsion explored by Forward and others.

  • Heath Rezabek December 8, 2013, 18:59

    One aspect of Nick’s line of thought that I find interesting and useful, though I may be in the minority, is that of a “peer civilization”. Since it risks being misunderstood, it’s worth putting a few words towards it here, esiecailly since it’s an idea that arose in conversation with Nick.

    At the time, we were discussing the fact that if a civilization is beyond our conceivable reach, mentally or physically, then whether or not it existed was immaterial on a practical level. It may as well not. This led to Nick jokingly phrasing the “Rare Peer Hypothesis.” Simply put, the idea that while life may or may not be abundant, those forms of life at a stage or in a form comprehensible to us or reachable by us seem to be minute. (Indeed, seem not to exist). “Peer” simply means “a potentially relatable entity.” If we cannot relate to it in any way, whether by virtue of distance in spacetime or distance in cognitive level, then its existence is inconsequential to our current state or thought — just as we would be inconsequential to them.

    However far our civilization progresses, at any point along the way our main concern when it comes to extrasolar civilizations will be whether or not they are — even potentially — peers.

    Since we are the ones doing the asking at the moment, I feel it’s perfectly valid to seek the presence or absence of peer civilizations when we think about these questions, and to orient our thought around that question since any other form of life is beyond our ken or as simple as our own basic life forms.

    One reason long term archival is my own answer to this conundrum is that the time-binding nature of symbolic communication has the potential to extend or stretch the span of our thought as we mature, or as whatever comes after us matures, so that it can encompass not only its own fleeting present but also some part of its vast past. Thus its potential to someday find a peer in the cosmos can grow through time.

  • James Benford December 8, 2013, 19:48

    Nick Nielsen continues to contribute new perspectives. A few comments:

    About footnote 4: The NIF experiments have not gotten to ‘near breakeven’. Livermore is just trying to redefine “scientific breakeven” downward to mean that the fusion energy was equal to, or greater than, the inwardly-directed kinetic energy of the radiation-driven pusher shell. That’s about a factor of 100 from what ‘scientific breakeven’ has always meant: fusion energy/laser energy = 1. And even scientific breakeven is at least a factor of 10 from energetic breakeven, which is openers for useful fusion power.

    Of course this is a moving-the-goalposts maneuver, continuing the long history of ICF pollyanna projections. This couples with hoping nobody remembers what was previously said.

    What to do now? One possibility now is falling back to lower-gain, simpler target concepts that had been abandoned in funding-driven down-selects.

    “We can in fact achieve inertial confinement fusion at an energy loss.” You can get energy out from fusion reactions, which was done a long time ago. But to make a fusion rocket is far harder: energy out must exceed energy in, or the ship runs out of energy, shuts down.

    Those who think city lights are observable at astronomical distances have not done the calculations. The luminosity of Earth from artificial lighting is 14 orders of magnitude less than the sun. This signal-to-noise ratio defeats such observation.

    James Benford

  • Wojciech J December 8, 2013, 19:54

    coacervate-the best bet now seem to be telescopic observations for first biospheres and then signs of technosignatures of advanced civilizations.
    For many reasons, that were discussed here before, radio signals aren’t the best way to communicate or detect others. SETI is far too much focused on them.

  • Wojciech J December 8, 2013, 21:12

    “The luminosity of Earth from artificial lighting is 14 orders of magnitude less than the sun. This signal-to-noise ratio defeats such observation”
    Advanced hypertelescopes would be able to take pictures of planets with resolution allowing imagining continents.
    With that city lights are easily visible.

    “City Lights Could Reveal E.T. Civilization
    http://www.cfa.harvard.edu/news/2011-30
    Cambridge, MA

    In the search for extraterrestrial intelligence, astronomers have hunted for radio signals and ultra-short laser pulses. In a new paper, Avi Loeb (Harvard-Smithsonian Center for Astrophysics) and Edwin Turner (Princeton University) suggest a new technique for finding aliens: look for their city lights.
    “Looking for alien cities would be a long shot, but wouldn’t require extra resources. And if we succeed, it would change our perception of our place in the universe,” said Loeb.”

  • Wojciech J December 8, 2013, 21:14

    James Benford:
    “The luminosity of Earth from artificial lighting is 14 orders of magnitude less than the sun. This signal-to-noise ratio defeats such observation”
    Advanced hypertelescopes would be able to take pictures of planets with resolution allowing imagining continents.
    With that city lights are easily visible.

    “City Lights Could Reveal E.T. Civilization
    http://www.cfa.harvard.edu/news/2011-30
    Cambridge, MA

    In the search for extraterrestrial intelligence, astronomers have hunted for radio signals and ultra-short laser pulses. In a new paper, Avi Loeb (Harvard-Smithsonian Center for Astrophysics) and Edwin Turner (Princeton University) suggest a new technique for finding aliens: look for their city lights.
    “Looking for alien cities would be a long shot, but wouldn’t require extra resources. And if we succeed, it would change our perception of our place in the universe,” said Loeb.”