August 09, 2010

Alone, or maybe not

Mention extra-terrestrial intelligence and most people will perk up and say "E.T.!", or maybe more likely in Bollywood-obsessed India, "Krrish!" (Forgive me, but what a painful movie). How firmly that ugly-but-cute puppet, or a perfectly muscled Hrithik Roshan, has been etched into our brains. So when we hear that there are people actually looking for signs from outer space of an intelligence other than ours -- assuming, for the time being, that we are intelligent -- it's almost amusing. What are they looking for, little green men? The Man in the Moon? Hrithik leaping from planet to planet?

Ha ha, but actually, none of those. The search for extra-terrestrial intelligence (SETI) is a serious scientific endeavour that many dedicated researchers have pursued diligently for years. It's a pity to think of it in terms of images from films.

But when you do give SETI some serious thought, a fundamental question comes up right away: How do you go about doing it? Answering it turns out to be extraordinarily difficult.

A major problem is the unimaginably vast distances in space. Our known means of travel are far too slow for humans to bridge them. Even our speediest spacecrafts would take 40,000 years to reach Alpha Centauri, the nearest star to us on Earth. And we don't even know if there is any life, let alone intelligent life, in the vicinity of Alpha Centauri.

Some scientists have suggested that we find other means to power such a spacecraft than chemical fuels. They imagine one that will slowly accelerate to close to the speed of light. At that speed, it would reach Alpha Centauri in a little over 4 years -- which is how long it takes light to reach us from there. But the energy required for such a trip would be enough to supply India's electricity needs for at least 100,000 years. Who has that kind of money to spend on a spaceship?

Clearly, manned travel is a thoroughly impractical way to carry out SETI. What about sending out unmanned probes? A good idea, you might think, but where would we send them? In just our own corner of our own medium-sized galaxy, we have thousands of stars, and we have no idea which of them, if any, might harbour an ETI. So sending probes to each of those stars would be an enormously expensive project. Yes, who has that kind of money?

What about transmitting radio signals on our own? Clearly a better option than travel, there are people who have tried this. But it will be a long time before we get any kind of reply -- again, from Alpha Centauri alone we'd have to wait over 8 years for one, if it comes at all. Also, we have to listen constantly for that reply, hoping that when it comes, we will be able to filter it out of the random radio noise that fills space anyway.

For all these reasons, scientists have decided that listening for evidence of an ETI is a better strategy than sending out either spacecraft or signals.

But even just listening presents hard, fundamental problems to address. For one, where do we turn our ears?

We can start by aiming radio telescopes at nearby sun-like stars. There are about 1000 of these within 100 light years from us. We can search them carefully for even weak signals, then work outwards to stars that are more distant. Another possibility is to scan the entire sky slowly, looking only for strong signals. The proper SETI strategy is likely a mix of these two methods.

Still, these are just the mechanics of carrying out SETI. Once we start listening systematically, we're up against even more fascinating challenges: What exactly are we listening for? What kind of signal would we recognize as the transmission of intelligent beings? If we get one, how do we interpret it? Once we do, should we respond? How?

A candidate ETI signal would be obviously artificial, to distinguish it from radio noise. Perhaps it would be a pattern of pulses and spaces broadcast over a period long enough to leave us in no doubt that it was produced by intelligent beings.

What would it mean, though?

Speculation is easy, sure. But there are some things we might be able to deduce from such a signal. A good first guess would be to treat each pulse as a one and each space as a zero (or vice versa). That would give us a message coded in binary, the simplest number system we know. But what do we do with this stream of ones and zeros? All kinds of things, really. We might look for patterns in the stream, then see if we can hit upon a code that explains them. Or we might arrange the digits in a rectangle instead of a line. If this is what the ETI had intended for us to do, and if we can hit upon the right dimensions for the rectangle, the numbers might form a picture, or some other information, that tells us more about these beings and where they live.

This is a plausible enough way to proceed that we ourselves have sent out just such pictures. One went out from the Arecibo radio telescope in Puerto Rico (an awe-inspiring machine by itself, filling an entire valley) when it was inaugurated in 1974. We aimed that transmission at a cluster of stars in Hercules, where it will arrive in about 27,000 years. That is, let's not worry too much about getting a reply.

Several SETI efforts have used these ideas for years now, but they have found no candidate signals yet. Is that discouraging? Well, they have only searched a little over 0.01% of the sky. There's plenty of reason to keep hoping.

But assuming we receive an ETI message one day, what should we do then? To me, it seems entirely possible that political, religious or economic compulsions will keep us silent. We might even be scared of replying. But if we do find the imagination to reply, we will probably send back a similarly coded message on the same radio band, and then wait for another message from the ETI. With the exchange of a few such messages, we will work out a logical way to send information back and forth.

Of course, given the distances involved, this "conversation" will be extremely slow. Again, with an ETI near Alpha Centauri it would be eight years before we got a reply to our message. With further stars, those who hear the first ETI signal on Earth might be dead by the time the next one arrives.

The constraints of space and time are a serious barrier to direct contact with any intelligent galactic neighbours we might have. Talking to them will be a slow, tedious affair; meeting them will remain a dream.

So you might wonder: why do SETI at all? Ah, but that has to do with our perpetual wonder about the unknown. All through history we have set off to explore dark corners of the world. Today, when there are pretty much no dark corners left on this planet, we turn to space. How can we not stop to wonder: is there anybody out there? Are we unique? Are we alone?

Answering those questions poses totally new challenges that need totally new thinking. How can we travel faster than our painfully slow spacecrafts now manage? Can we find a better medium than radio waves to carry our messages? How do we send out a signal that will not seem threatening to an ETI?

What's fascinating about all this is that it makes us consider ourselves more closely. Do we have the patience, the vision, the courage, to sustain a long and frustrating SETI? If we can't resolve our own petty quarrels, how will we seem intelligent and friendly to an ETI? If we ignore lessons our own history teaches us, what will we learn from an ETI?

For me, this is the most compelling thing about SETI: that a search for something entirely outside our home planet, even our imaginations, eventually makes us look at ourselves anew. In the end, there's the greatest reason to do it at all.

14 comments:

wise donkey said...

didn't we hear a mysterious sound from space some time back?

was aware abt seti but not this much details.

if eti ever comes here, they would just have a good laugh and then talk to some other species.

or may be they are worse off:)

Jai_C said...

dilip,

Apologies if this comes across as a trollish comment*, but I would rather have govt money spent on addressing the needs of our poor than on say a world class SETI facility (however cost-optimized in terms of radio listens).

I am more than happy to leave SETI to the wealthier countries. I am okay with private individuals/ organizations spending their money on SETI if they want to.

I see value in space satellites and launch facilities but have never been comfortable with Chandrayaan.

thanks,
Jai
* I just got done with the T3 post so its still in play. Am not sure whether this comment is inline with your new policy. Feel free to delete it if you think its not.

Chandru K said...

I have always found the size of the universe both fascinating and awe-inspiring. To think, to get to the *nearest* star in our galaxy would take 40,000 years with present technology. What about stars much farther away in our galaxy, and what about other galaxies? One galaxy, the Andromeda, is so distant, that it appears to us only as a speck of light. But that is an entire galaxy with millions, perhaps billions of stars!

Anonymous said...

more than 3000 were killed in 1984 and then in 2002 some more were killed.. aur yeh banda SETI ke baare mein likh raha hai

Chandru K said...

Actually, it may interest people that India has some pretty good facilities for the study of astronomy, both radio and optical. A few of them are considered world class. With the upcoming dedicated astronomy satellite "Astrosat", slated for launch next year, expect some cool observations and discoveries by Indians in the galactic vastness.

Chandru K said...

"but have never been comfortable with Chandrayaan."

Chandrayaan was a disappointment only in the sense that it did not last as long as its creators were hoping. But it was a great and successful first time journey to the moon for India; the launch and the successful manoeuvering of the spacecraft from an earth based to a lunar based orbit, was highly impressive. Several countries failed at this tricky operation on their initial attempts.

A few significant discoveries have already been made. There will be more forthcoming, no doubt, as all the data is being analysed.

ori0nis said...

Reminded me of the SETI screensaver I used to have on my desktop (I wonder if a similar collaborative effort could be used to receive signals from outside -- we have a dish atop every house these days) Too bad last I heard Arecibo had some funding issues.

Life is a cruel joke said...

The other problem is recognising a signal as a message. i.e. we have to get the 'meta-message' so to speak. We have been sending out radio signals to Alpha Centauri for donkey's years now (with apologies to wise donkey). have we been able to decipher any noise from there as a signal? Have we received our own signal back as an echo? These questions will probably guide the path of the SETI

Dilip D'Souza said...

ori0nis: yes, what happened to that parallel processing screen saver effort? Is it still on? Where do I find out?

Life, that's the issue: how do we tease out a real signal from all the noise? An interesting challenge by itself.

Ketan said...

Dilip,

I loved your euphemism: "That is, let's not worry too much about getting a reply". Hahaha!

You might've read 'The Andromeda Strain' by Michael Crichton. And if not, nor am I recommending it. The only take-away message from it was that 'life' as we know it, if found in outer space, is extremely unlikely to be hominoid. Forget hominoid, it might not be based even on nucleic acids - DNA & RNA.

So first, even if we find a semblance of life in outer space, that in itself would be a huge discovery. You'll find something related at the end of this (click) blog post [not written by me! ;) ].

Of course, you've clearly indicated that your article focuses on 'intelligent life'. But in all honesty, I find SETI's premises and attempts at contacting extraterrestrial life comic. This could perhaps be because, of late (in last 4 to 5 years) many things are failing to excite me [a lot of what follows in this comment could be considered irrelevant to the post.] I experience exactly same type of indifference towards prospect of celebrating Diwali, New Year or of observing a total solar eclipse! I, now think of solar eclipse only as light-and-shadow play between the Sun, the Moon & the Earth - what's so special, apart from scientists getting to see, 'corona' - which anyway I won't be able to learn much about? I feel exactly the same kind of indifference towards the prospect of finding organic chemicals-based life elsewhere. Yes, humans have not been able to create life from inorganic substances yet. There's one huge challenge - nucleic acids cannot be synthesized without enzymes (proteins) & larger peptides (proteins) need nucleic acids as templates for 'polymerizing' from amino acids. That's a bit like chicken & egg-puzzle. But apart from that how biomolecules give rise to living organisms is not a big puzzle any more.

My above part of comment is not meant at all to be a disapproval of enthusiasm people feel at the idea of finding life elsewhere, in fact, rather I'm worried what's happened to my curiosity & enthusiasm! Why don't I find these things exciting any more?...

Ketan said...

...Somehow I feel, excitement to discover new things & curiosity should be functions of one's age, i.e., younger people should be more excited about phenomena like ET & solar eclipses! So, my own disposition surprises (& worries) me. Anyway, enough of speaking about myself!

Somewhat on the topic: I'd read that scientists are trying to find out genes that could induce hibernation in humans, which would serve to greatly retard aging by reducing the metabolic rate. Perhaps, cooling the body might also be tried. So, it is hoped that these measures would allow for much longer journeys across the space.

But there's one more huge challenge to space travel that people ordinarily do not appreciate - loneliness & resulting depression. Both lead to strong suicidal tendency. Space gets very monotonous in a very short time. I guess, I'd come across these ideas on Discovery Channel.

Last thing (off-topic, but this is something I feel very strongly about, so hope it would not be viewed adversely) - this post reminded me of one of your older posts where I'd commented - it had something to do with Red & Blue doppler shifts. You're an exceptionally good writer. Why do you not try writing (science) books for children? This I say because I'm totally appalled by the quality of education in India. Schooling is infested by ideas of 'cracking' entrance & board exams. And unfortunately, this sort of cracking's nothing to do with understanding concepts well. This problem's much worse with biology. Somehow, high school students end up developing some interest in maths & physics, but biology, because of very low quality of textbooks is considered to be a subject to be memorized. It was an accident that I got fascinated by biology because of how a foreign-authored book introduced life ("life is a series of chemical events" or something like that). But others still view biology with disdain. In the US, there are proposals to introduce philosophy as a subject in school to inculcate a spirit of critical enquiry. Whereas in India, we seek to indoctrinate students with 'moral science'! My suggestion to you of writing books for children, if it comes out as silly, I apologize. But I seriously feel, if there's any hope to salvage India as a civilization, it's only through the next generation....

Ketan said...

...Now let me elaborate on why I stress on teaching 'good quality' science & philosophy to children to salvage the civilization. My ideas veer into amateur psychology, so could be entirely flawed, but do see if they make intuitive sense to you:

Both philosophy & science require one to question any assertion put forth. Both require that we be aware of the premises on which we base our inferences. A person trained in these subjects is therefore much less likely to accept a statement made in any realm of life without scrutinizing it logically. There would be two major consequences of that: one, senseless rhetoric (largely emanating from religious indoctrination & meant to promote jingoism) would be outrightly rejected. E.g., I feel, "everything's fair in love & war" is a most senseless assertion. It cannot stand a simple "why?". But such assertions have been used to justify worst crimes, simply because we're too taken in by rhetoric, and do not even question it. Two (which would not make immediate intuitive sense), a person questioning things & trying to understand phenomena is less likely to respond to them on an emotional plane. E.g., those understanding that human sexuality's a spectrum, & homosexuality & bisexuality are merely two different points along it are much less likely to hate homosexuals & bisexuals.

So, I'm hoping that people who're sensitized to the idea of trying to understand everything rationally, including human psychology & their own motives, would be much more empathetic & introspective. Apart from being more patient & tolerant, they might end up being more ethical, as they'd have learned to view their own instincts & impulses in 'slow motion'. E.g., it's much easier to employ projection (ego-defense mechanism) out of jealousy, blame someone else & 'punish' them cruelly if one does not introspect. But upon introspection if one recognizes jealousy in one's mind, the unethical nature of one's motives would become apparent, & it'd be very difficult to continue with the idea that 'I'm right & the other person wrong'.

My ideas might seem silly (& perhaps they're), but it is for above reason my thrust to improve mankind has been on critical enquiry. It's important to inculcate the attitude of questioning everything - be it inside one's mind or outside. And it is at this level, books that people like you might write for children - making them think - could be catalysts for a better society.
Thanks!

Ketan said...

...Now let me elaborate on why I stress on teaching 'good quality' science & philosophy to children to salvage the civilization. My ideas veer into amateur psychology, so could be entirely flawed, but do see if they make intuitive sense to you:

Both philosophy & science require one to question any assertion put forth. Both require that we be aware of the premises on which we base our inferences. A person trained in these subjects is therefore much less likely to accept a statement made in any realm of life without scrutinizing it logically. There would be two major consequences of that: one, senseless rhetoric (largely emanating from religious indoctrination & meant to promote jingoism) would be outrightly rejected. E.g., I feel, "everything's fair in love & war" is a most senseless assertion. It cannot stand a simple "why?". But such assertions have been used to justify worst crimes, simply because we're too taken in by rhetoric, and do not even question it. Two (which would not make immediate intuitive sense), a person questioning things & trying to understand phenomena is less likely to respond to them on an emotional plane. E.g., those understanding that human sexuality's a spectrum, & homosexuality & bisexuality are merely two different points along it are much less likely to hate homosexuals & bisexuals.

So, I'm hoping that people who're sensitized to the idea of trying to understand everything rationally, including human psychology & their own motives, would be much more empathetic & introspective. Apart from being more patient & tolerant, they might end up being more ethical, as they'd have learned to view their own instincts & impulses in 'slow motion'. E.g., it's much easier to employ projection (ego-defense mechanism) out of jealousy, blame someone else & 'punish' them cruelly if one does not introspect. But upon introspection if one recognizes jealousy in one's mind, the unethical nature of one's motives would become apparent, & it'd be very difficult to continue with the idea that 'I'm right & the other person wrong'.

My ideas might seem silly (& perhaps they're), but it is for above reason my thrust to improve mankind has been on critical enquiry. It's important to inculcate the attitude of questioning everything - be it inside one's mind or outside. And it is at this level, books that people like you might write for children - making them think - could be catalysts for a better society.
Thanks!

Dilip D'Souza said...

Ketan, as much as I hate to admit it, I'm no longer young. But even if I know the simple explanation for eclipses, I still find them exciting. With the last one that was visible in Bom, I think in Jan, I caught one of my favourite sights: the way the light comes through a thickly leaved tree overhead and you can see crescents of light in its shadow. A delight!

Thank you for your compliment, I am touched and honoured that you feel like that. I've thought about teaching maths to kids so that they will learn to love it as I do, which I think is something lots of kids need and that perhaps I can do. But I've never thought of writing science books for kids. Thanks for the suggestion and I will think about it seriously.