The weekend is a good time for a topic like SETI — the search for extraterrestrial intelligence. At PhysOrg we came across UK launches Search for ExtraTerrestrial Intelligence Research Network. The first half of the article is about stuff like this:
A network has been launched to promote academic research in the UK relating to the Search for ExtraTerrestrial Intelligence (SETI). The UK SETI Research Network (UKSRN) brings together academics from 11 institutions across the country. The network’s Patron is the Astronomer Royal, Professor Martin Rees. UKSRN will present current activity and consider future strategy in a session and panel discussion at the National Astronomy Meeting in St Andrews on Friday 5 July.
That meeting has already come and gone. Here’s the new outfit’s website: UK SETI Research Network. It doesn’t tell us much, but it gives a link to the website for the conference: UK National Astronomy Meeting NAM2013 1-5 July 2013. We don’t find much there either, but the PhysOrg article has some good material which ought to get your juices flowing. For example, they say, with bold font added by us
Back in 1950 during a conversation on SETI, the physicist, Enrico Fermi, posed the question ‘Where is everybody?’ The paradox between the high estimates for the probability of the existence of extraterrestrial civilizations and the lack of contact or evidence remains a key area of SETI research. Dr Anders Sandberg, of the Future of Humanity Institute at Oxford University, is investigating the question of how far away in space and time a civilization could start and still have a chance of interacting with Earth today.
The Fermi paradox is at the heart of all SETI work. Let’s read on:
“If this were a very limited range, the Fermi question, “Where are they?” would be easy to answer: they couldn’t have got here yet. However, we show in our paper that, beyond a certain technological level, civilizations can spread not just across their own galaxy but across enormous intergalactic distances. This is mostly limited by how fast their devices are and the expansion of the universe. There are millions or billions of galaxies from which a civilization could have reached us, if it were established early,” said Sandberg.
So where are they? We continue:
Sandberg and his colleagues have concluded that the answer to the Fermi question is more extreme than normally thought. “If life or intelligence is rare, it must be millions or billions of times rarer; if advanced societies wipe themselves out, or decide to not go exploring, they need to converge to this outcome with extremely high probability, since it only takes one that escapes this fate to fill the universe,” said Sandberg.
Great stuff here, but we’ll have to skip a lot. Here’s something to ponder:
[Dr Austin Gerig, senior research fellow in Complex Networks at the University of Oxford] and his colleagues have focused on a specific consequence of this reasoning, called the ‘universal doomsday argument’: long-lived civilizations must be rare because if they were not, we would find ourselves living in one.
“If most civilizations are small, then our own civilization is likely to be small, i.e., it is likely to die out within the next few centuries. Our research indicates this is the case, but that our estimates of survival are greater than previously thought using a more traditional form of the doomsday argument,” said Gerig.
There’s lots more in the article, and there’s also your own speculations — Where is everybody? If they’re out there, why don’t we see any trace of them?
Your Curmudgeon’s own primitive thinking is like this: Assume we could travel at, say, around one-third of lightspeed, so that a large shipload of settlers could travel to a nearby star in about a dozen years. We can’t do anything even close to that now — our chemical-propelled rockets travel at far less than 1% of lightspeed — but it’s not unreasonable to project that we could develop the technology to do better.
Then assume that stars with habitable planets are, on average, not more than about 5 light years away from each other, so we can gradually expand our domain without encountering any impossible distance barriers. And then assume that each new settlement — if educated and well-equipped — could develop itself sufficiently so that in, say, about three generations (less than a century) it would be able to launch some of its own people to settle the next habitable system. Population growth will be the biggest constraint to such rapid expansion, but once a new world is settled more ships will arrive, so population shouldn’t be a problem.
If those assumptions are reasonable — and we’ll all be dead before anyone really knows — then the domain of human-occupied space can expand every century at a rate of roughly 5 light years in every direction. That’s a sphere which grows 10 light years in diameter every 100 years. In a thousand years the sphere of human-occupied space will be 100 light years across. That’s nice, but it’s no big deal. There could be several isolated pockets like that here and there in the galaxy, but they’re so far away that we’ve never noticed them. However, it doesn’t stop there.
Multiply our expansion time by 1,000, and conservatively assume no technological improvements over all that time. You get a sphere of human space that’s 100,000 light years across in only a million years. Think about that. The Milky Way galaxy is roughly 100,000 light years across. If our projection has any validity, then we could occupy the whole galaxy in a mere one million years — that’s a blink of an eye in the lifespan of the galaxy. If we could do it, then why hasn’t anyone else already done it?
There could be many reasons why we appear to have the Milky Way all to ourselves. There’s a small library of literature on the subject. Whatever the reason may be, at the moment we seem to be presented with an opportunity that comes only once in the lifetime of a galaxy — we can be the first to occupy it all. So why don’t we get busy and do it?
If some other species does it before we do, then we’ll be dependent on their benevolence for our very existence. Maybe they’ll treat us well (they’re often so kindly in the movies), but maybe they won’t. Our own history of encountering primitive people around this world isn’t very pretty. There’s no reason to expect that some other species will behave better toward us than we have done to our fellow humans. We’ll probably behave better than we have so far, but it would be best to let others worry about our benevolence rather than the other way around. Anyway, if we can be the first to occupy the galaxy we ought to get started.
Copyright © 2013. The Sensuous Curmudgeon. All rights reserved.