Wednesday, June 28, 2006

The Fermi Paradox

Have you ever looked up at the sky on one of those nights where the sky is clear and the stars shine with a beauty unmatched and un-captured by any work of art? When you did, did you find yourself wondering if there was any other intelligent life out there? After all there are up to 400 billion stars in our galaxy alone and there are about 100 billion galaxies. With such mind numbingly huge numbers, no matter how rarely life appears, surely there must aliens out there? Mustn’t there?

Back in the 1950’s a man by the name of Enrico Fermi asked himself the same question. But Enrico was smarter than the average bear and he new a lot of stuff about a lot of stuff. He was a physicist and knew how to work with big numbers, so he started drawing up calculations. He realised that if the people on Earth really wanted to (and they would have to really want to) then within the next couple of centuries they could build space ships that could reach nearby stars. These wouldn’t be your Captain Kirk, warp factor 9 space ships, which could get you to Sirius in time for tea. These would be slow, big ships which would take decades. They would be one way tickets and the passengers would have to build a colony. But they would do it on a new planet around a new star. Then, thinking a bit more, Enrico decided that within a few centuries these colonies would probably send out their own ships and start the process again. If, on average, each colony created two more colonies then the whole galaxy would be full of humans in about a million years.

Only trouble was that Enrio knew something else. The sun is a second generation star and (for reasons I won’t explain now) only second generation stars can support life. It’s been around for 4.5 billion years, which makes it middle aged. Some second generation stars are much older. Billions of years older. And if one of these stars had of had a race of little green men grow up on one of its planets, then they would have been buying up the real estate on Earth long before the Dinosaurs got their turn.

So where on Earth, and I do mean on Earth, are they? Did they all decide to stay at home? Did they all die in a nuclear war or plague? Maybe some of them stoped, maybe some of them had a cold war that turned hot. But all of them? Every one? Because it would only take one to keep going, get lucky and fill the galaxy.

Ok, so maybe Enrico was wrong. Maybe it’s just too hard and everyone has stayed at home. No colonies, no captain Kirk. Just one very final frontier. But that’s not the end of it. Every day our TV programmes, ham radio calls and mobile phone calls get beamed into space. Not deliberately, but out they go and they go for ever. Somewhere, 44 light years away, the original broadcast of Doctor Who is heading out into the vast unknown. And the same should be true of our alien cousins. Our radio telescopes are fine enough to detect the faintest whisper of the broadcast of Big Alien Brother anywhere in the galaxy. We do listen and we are very good are recognising random static from an encrypted message. But we haven’t heard anything. It’s as silent as a grave!

And this is the Fermi Paradox: The stars suggest that extraterrestrial life should be common, but where are they? Maybe we are alone.


At Thursday, June 29, 2006 10:05:00 am, Blogger David Brewer said...

There was a great programme which touched on this on Radio 4 this morning. It was Melvynn Bragg's 'In Our Time'

You can dowload, listen again, or save for your MP3 if you go here..

Below is the programme tease.


Ours is about 100,000 light years across, is shaped like a fried egg and we travel inside it at approximately 220 kilometres per second. The nearest one to us is much smaller and is nicknamed the Sagittarius Dwarf. But the one down the road, called Andromeda, is just as large as ours and, in 10 billion years, we'll probably crash into it.

Galaxies - the vast islands in space of staggering beauty and even more staggering dimension. But galaxies are not simply there to adorn the universe, they house much of its visible matter and maintain the stars in a constant cycle of creation and destruction.

But why do galaxies exist, how have they evolved and what lies at the centre of a galaxy to make the stars dance round it at such colossal speeds?


John Gribbin, Visiting Fellow in Astronomy at the University of Sussex

Carolin Crawford, Royal Society University Research Fellow at the Institute of Astronomy at Cambridge

Robert Kennicutt, Plumian Professor of Astronomy and Experimental Philosophy at the University of Cambridge"

At Thursday, June 29, 2006 10:06:00 am, Blogger David Brewer said...

Sorry, link didn't wrap, let's try again. This might work.

In Our Time

At Thursday, June 29, 2006 10:57:00 am, Blogger Heavy Green Ink said...

Thanks Dave, I'll have a listen to that latter.

John Gibbins is a first class science writter. I really reconmend "In Search of Schrodinger's Cat" as one of the most accessible science books I've read on what is a very complex area.

At Friday, June 30, 2006 2:53:00 pm, Blogger David Brewer said...

Drinking with my chum last night and he reckoned that the enormity of having 100 billion galaxies made him more convinced about there being a god, whereas I find it has just the opposite effect. Strange that. In fact I find that argument almost as hard to get my head round as the Fermi Paradox itself – or is it the same thing?

At Friday, June 30, 2006 5:54:00 pm, Blogger Heavy Green Ink said...

Take a look at the Anthropic Principle . No one seems to link it to Fermi's paradoz, but maybe they should. Maybe I should write a short introduction to that too.

At Friday, June 30, 2006 8:40:00 pm, Blogger David Brewer said...


At Friday, June 30, 2006 9:43:00 pm, Blogger Heavy Green Ink said...

You don't think I could write a short introduction to the Anthropic Principle, or you don't think I could write a short introduction period?

At Friday, June 30, 2006 10:10:00 pm, Blogger David Brewer said...

The shorter the better because if something must be true for us to exist then it is true because we exist.

At Friday, June 30, 2006 10:21:00 pm, Blogger Heavy Green Ink said...

That's the Weak AP. The recent (late 90s I think) discovery that the universe's expansion is speeding up seems to kill that idea.

At Saturday, July 01, 2006 7:16:00 am, Blogger David Brewer said...

I am okay with concepts of quantity of things but get confused with concepts of infinite space. Is there a theory or recommended reading about what is beyond it all?

At Wednesday, July 19, 2006 11:49:00 pm, Blogger keepthefaith said...

They must be there, pure statistical analysis says so, we are here, so they must be there. They are avoiding us until we are "grown up " enough not to leap into monkey defence... (If you can't blow them up, use banana skins!)


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