Wednesday, August 17, 2016

All those little LGP (Little Green People) out there: A space fantasy

Ah, yes, the highly publicized, if not hyped, search for planets with life 'out there'!  A promotor's dream, because how can you ever falsify the idea that we're not in this alone?  NASA and other funding-hungry semi-sci-fi agencies continue to drop hints about habitable planets and so on.  You know the patter, and the promises almost as flagrant as those of 'precision' genomic medicine.

Well, forget the hype, promise and 'artist' impressions, and let's take a little look at what is in a sense being promised.....

First, let's go back to Aristotle's time and before, and imagine space as a crystal sphere in which the Earth is centered. That is, what we can see is the encircling sky dome.  There we peer into the stars, galaxies, and so on.

Now let us suppose that there really is 'life' out there, and as a short-cut for our purposes here let's further suppose that what we mean by 'life' is living organisms that are advanced enough to use and/or transmit electromagnetic waves strong enough to reach Earth detectably.  Now, to make the SETI (search for extra-terrestrial intelligence) effort easier, let's imagine that these particular emanations can be discriminated from all other sources of electromagnetic radiation in the skies, like light from stars, microwave background from the Big Bang, and so forth--that is, so we can specifically visualize the life-signals' beams by their being green.  I pick green so we can think of them as being (intentional or not, but at least direct evidence) from the Little Green People (LGP) that are out there--if any of them are. That we exist suggests that thinking that life of interesting sorts exists elsewhere is not particularly surprising, and it must have many forms we might not even recognize.

So, let's grant NASA's and the ESL's (and sci-fi writers) wishes and assume that not just life but LGP are out there.  Indeed, let's make our effort to contact them really, really easy, and simply assume that there are millions of planets, even just in the visible universe, that have such LGPs on them.  That's at least plausible; whether it's probable can't be said because we have no way to evaluate what 'probable' would mean.

The figure very schematically suggests what I mean.  The ring around the Earth represents what we can see today. Again, we assume we can discriminate the 'green' radiation from all the other radiation coming in.  The length of each arrow represents the length of time the civilization out there was sending a signal, and let's allow these to be for millions of years (note I'm being very generous: for example, any human-sent signal emanating from Earth would only be about 100 years' long, since radio signaling is only that old).  The place of origin will usually millions or billions of light years away, way, way, way beyond this figure, and the signal has taken that number of years getting here, as it's doing just now when we see it.  After the end of an arrow, that civilization was no longer sending, probably no longer exists, but we don't know that until the end of the signal arrives.  Before the arrowhead, the civilization hadn't developed appropriate signaling technology, so we can't know it is (or was) there.   Incoming signals outside of that ring are not yet visible to us--we don't know they're on their way here and have no way to know those LGP civilizations even exist.

The green-dappled sky
OK, envision our celestial globe, with its hundreds of billions of stars in the Milky Way, and the hundreds of billions of similar galaxies we know are in the heavens, again, just considering our 14 billion year old universe's visible horizon, which is I think tens of billions of light-years in diameter. If life is here on Earth, why not all over the place out there?  There are similar environments, presumably, in countless planets.  At any given moment, we would see green dots on the celestial sphere wherever an LGP signal was incoming.

So, let's say, just to be as favorable to the LGP search as possible, that we see a million such dots. That's not implausible, and let us assume, again to be generous, that each emitting population actively disseminates electromagnetic radiation for a million years, from the time they developed the technology until they evolved on to extinction or disinterest or whatever.

This should mean rich hunting grounds.  But I think it does no such thing.

By far most, if not essentially all such LGP emanations will be from more than a million light years away from Earth.  That means that by the time we can detect them, the emanations will have stopped and the people probably become extinct (many reasons, such as their local star blew up, they evolved to some other species, they damaged their environment beyond sustainability, they overpopulated themselves into starvation....).  And of course, we have no idea just by seeing a dot whether it's one of those, or one from a still-living source.

Even if such a source were still viable, and even if we guess right about which one that may be at the time we mount an expedition or sent a 'Hello!' message, it would likely take 'us' so long to reach them, with either generations of astronauts in transit or just a radio signal, that the LGP would be done-for by the time we or our signal got there.  A manned expedition would take hugely more generations than have ever existed for our species, of course.  And, of course, no matter how clever they were, the LGP wouldn't be able to detect us for millions of years after we sent our message to them, assuming they were still alive at that time so distant from when we received their emanation.  And, of course, we'd be extinct or would have polluted the Earth out of life, by the time any such contact occurred.

So, it is essentially hopeless to wave around vague suggestions of finding 'life in space'.  In fact, most of the universe isn't just a few millions of light years away from us, it's billions of them.  Even hinting at connecting with LGP borders on fraud by those who want our attention, and funds, to explore these possibilities.

The hopeful (sort-of) side
However, there is, surprisingly (sort of), a hopeful side.  That's because if there in fact are LGP out there, most of their signals won't be visible to us at any given time.  Millions or billions or even trillions of little green dots may be approaching us from any or all directions, but just haven't gotten here yet.  That would only be expected if we can see a million of them at our particular time today.

Out of all of those incoming signals, maybe some are close enough to us to constitute something to be excited about....except that once we see their blip, it will at best have been sent at the beginning of their signal-generating lifespan and we'll have no idea how long ago that happened, and hence whether they're still there and sending, so we can't know how long the blip will keep appearing, and most of the time the signal will be millions if not billions of years old, and as above, the senders long-gone.

If some movie or video game outfit develops a real tele-transporter or wormhole traversing system, we might dream of going 'there', wherever there is.  Even then, we'll have to choose which of the million green dot sources to travel to, and just hope the senders are still there.  Of course, they're not really green, so choosing light blips to pursue won't be easy!

There are enough fascinating things about space, and enough real, not imaginary, needs right here on our green earth.  We should keep fantasies to the world of fiction.


Michael Finfer, MD said...

"That means that by the time we can detect them, the emanations will have stopped and the people probably become extinct (many reasons, such as their local star blew up..."

A minor correction to astrophysics, the stars that are massive enough to become supernovas probably do not live long enough for intelligent life to evolve, only a few tens of millions of years. That is not one of the reasons why we have not found anyone else so far. Everything else you say is valid, and I am sure there are plenty of additional reasons why we seem to be alone.

There was an unconfirmed report in the news yesterday that scientists have found an earth-like planet orbiting in the habitable zone around Proxima Centauri, only 4.25 light years away. If true, this is the only exoplanet that is potentially explorable in the next few centuries. I think we will find life elsewhere eventually, but I have my doubts about complex life.

I am willing to be proven wrong.

Ken Weiss said...

Thanks much for the correction. In any case, if not by a blow-up, stars will die out or life on a planet will, etc.
As to life a 'mere' 4.25 light years away, even if we assume the fantasy of a habitable place 10 ly, say, and can travel at 25% the speed of light with a sent-ahead supply chain and all that, it would take 40 years to get there. Astronauts starting out at age 30 would be 70, so we'd have to have either in-flight reproduction (a lot for sexy sci-fi writers to envision!), or cryopreserve future rounds of crew to waken them along the way. An emergency half-way there that required earth-based fix instructions would take 40 years for the answer to arrive. It's fantasy and we're paying for it in taxes. So my view is that the video industry should do that, and sell tickets. We have better things to do with public funds, no matter how truly fascinating space is.

Michae, Finfer, MD said...

You are neglecting time dilation. People on earth would age 40 years during that 40 year mission, but the astronauts would not.

I was thinking of the recent proposal to send a swarm of nanoprobes to a nearby star, by the way, not a manned mission. I have a sinking feeling that crewed interstellar travel will turn out to be so difficult that it will be essentially impossible.

Ken Weiss said...

Well, time dilation is roughly proportional to speed relative to c, no? So they'd only age 36 years instead of 40? Anyway, if resources were spent on learning things about space rather than on costly fantasy adventures, there'd be less to grumble about.

David J. Littleboy said...

"Anyway, if resources were spent on learning things about space rather than on costly fantasy adventures, there'd be less to grumble about."

Agreed. Completely. (Although manned space flight is a far worse waste of money than the SETI silliness.)

And it's worse than you think. Consider spread-spectrum communication (frequency hopping). If you don't know the pattern the carrier frequency is switched with, you can't tell the difference between a strong signal and background noise. Any civilization that has an individual about as smart as Hedy Lamarr* will invent frequency hopping, or something a lot more complicated.

*: She and a pianist/composer friend were looking at their piano keyboard and thinking about the problem of allied communications being jammed and thought, hey, if we just keep changing the carrier frequency like a melody, the enemy won't be able to figure out what frequency to jam. Kewl in the extreme. (If you're a nerd.)

Ken Weiss said...

Things like the space station, new manned Moon or manned Mars flights are a major waste of public money. The amount learned and there'll always be some, doesn't justify. Or, put another way, this sort of thing is probably within the budgetary abilities of the video industries. Deep probing telescopes and that sort of thing can tell us about the universe we're in in a way that is much more not just scientifically important,but also edifying. The engineers' notable talents could be put to much more constructive use right here at home.....

David Evans said...

If we picked up a signal from 10 LY away, we would of course aim all our best instruments at the source, in the hope of finding out what sort of planet it came from and therefore how like us the sender was likely to be. We might even be able to eavesdrop on some of their other activities. At minimum there would be a huge increase in public interest in astronomy with (one hopes) an increase in funding.

Of course our next step would be to reply in kind rather than send a spaceship on a 40-year journey.

Ken Weiss said...

I don't try to keep up on the details, but I think the skies within more than 10 LY have been pretty well scouted, for quite a while (by SETI enthusiasts at least). I am not a physicist and can't say what realistic sort of LGP signals even from as close as 10 LY would even be detectable, not to mention recognizable. I agree about the interesting nature of any such findings, but I think we're being conned by NASA's publicity machine to tempt people, even vaguely or deniably, to think about such 'life' and its visitability.

I probably disagree about the funding, since there are so many seriously deprived lives right here on earth, so to me social politics go beyond just the scientific question. Beyond that, to me, if we invested in telemetry, even things like LIGO, to understand the cosmos, in seriously new ways, and kept the promises and hype down to earth, so to speak, that would be more justifiable.

I'm not (just) jesting when I say the video game and entertainment industries should be paying for Pluto ventures and their like, and selling access to the images. And maybe SpaceX can have space stations if they want. But tax money is wasted on those things, while urgent needs here go to waste. Again, this is a social view, separate from the genuine fascination with what's really out there.

Ken Weiss said...

Hey, stop the presses! Today it's Proxima B, a mere 4LY away, that 'might' be compatible with life. So says the latest ES spin-doctory. This is probably the one Dr Finer's comment (above) referred to. Well, this space rock may not have an atmosphere and maybe too intense x-rays, but maybe not! There's always hope to spin a tale around. So pack your bags.

As we discussed above in these comments, a mere 4 LY away means that if you travel at 10% of the speed of light it'll only take you 35 years to get there.

Ken Weiss said...

For some similar, but more detailed, comments about this sort of thing, see

One advantage explorations within our solar system has been--correct me if I'm wrong!--that we can use gravitational pull of other planets to slingshot a spacecraft, helping its speed and requiring less onboard fuel. Going out to deep-space, even nearby, will probably have little if any such assistance.