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Monday, 17 November 2008

Would you like to swing on a star?

Wow! They’ve captured an image of a planet circling a star 25 light years away. That’s quite some distance. Even though the planet isn’t exactly small (about three times the size of Jupiter), it’s pretty amazing. 25 light years – that’s the distance it takes light to travel in that time. Light’s not a slow coach either. Travelling at 186,000 miles a second it makes short work of going from here to the moon (a couple of seconds) and to the sun (93 million miles away in 9 minutes). So 25 light years is around 25x60x60x24x365x186,000 – that’s 146,642,400,000,000 miles. Read it out...” One hundred and forty seven million, million miles.”

Astronomers here on earth have been able to see a planet that far away. Ah, but I hear you say the star the planets circling is visible to the naked eye (just). That’s true, except the planet is around 1 billion times dimmer than the star!

Fancy visiting the planet? I can give you the co-ordinates to plug into your Sat – Nav and head into infinity and beyond. If you travel at the speed of, say, a space shuttle you’ll have plenty of time to write “War and Peace” and some. If you could travel at 186,000 miles an hour that would be nearly 4000 times slower than light. But the shuttle travels at about 18,000 miles an hour. So it would take you approximately 1 million years to get to this new planet.

And that’s only the beginning. At 25 light years the planet is not just a near neighbour it’s pressing its nose up against our faces – astronomically speaking. Our galaxy the “Milky Way” is some 90,000 light years across. That’s quite big. And yet that’s only the beginning. The farthest object observed by man is some 13 billion light years from us. It’s a galaxy so far away that the light we see from the galaxy set off on its journey 13 billion years ago. That’s an immense, almost unimaginable, expanse of time and distance. Yet the universe itself is much larger – around 150 billion light years across.

I’m fascinated by big numbers – it’s exciting. As a kid I tried to imagine the biggest number in the world. “Thousand, a million, a billion, a trillion, a zillion …a…dillion..” After a while I ran out of made up numbers. Google, the search engine is appropriately named – a googol is a very large number 10 followed by 100 zeros or 10 raised to the power of 100. (Note: if you type “googol” into Google, you’ll get half a million references. Type in Google you’ll get 2 billion references!) Then there’s a googolplex. It’s a monster of a number - 10 raised to the power of a googol, or 10 to the power of ten all raised to the power of 100. It’s so huge that if you tried to write it in numerals it would be bigger than the size of the universe. So even if you were travelling across the universe at the speed of a space shuttle you wouldn’t have enough time to write it out.

But we don’t need to imagine such distances or numbers to be awed. We don’t need to imagine worlds across the universe to invoke the expectancy of intelligence and the possibility of contact with minds similar to our own. NASA’s Galileo mission to Jupiter in 1995 beamed pictures of the unusual surface of Europa, one of the planet’s largest moons. The surface appears to be ice. Not ordinary Artic or Antarctic ice, but ice some 100 km thick and beneath that liquid water. The huge gravitational tidal forces generated by the host planet on Europa create enough energy to keep the water liquid. The possibility that this huge subterranean ocean might support life is tantalising.

In her 1978 science fiction novel “Up the Walls of the World” Alice Sheldon described the planet Tyree, a life-rich gas giant inhabited by intelligent beings resembling mantra rays or cuttlefish which ride the air currents of its vast atmosphere. Is it too fanciful to suggest that Europa’s vast ocean might support something similar? Time and time again our views on the boundaries of life have been confounded. Life, rather than delicate and confined, appears to surface whenever it’s given the slightest opportunity.

There is also some evidence that life, or at least, the complex organic compounds which form the basis of life on earth were not created here, but in deepest space. Earth and other planets were seeded by showers of this organic material. Given the right conditions life exploded. Because of this some people have suggested that the universe is teeming with life. Yet the universe we live in is extremely quiet. If life is so plentiful why aren’t the heavens alive to the chatter of billions of civilisations? Surely if life is so prolific we cannot be the only sentient beings to have discovered electromagnetic radiation.

Enrico Fermi, the eminent nuclear physicist thought up this intriguing paradox -the apparent size and age of the universe suggest that many technologically advanced extraterrestrial civilizations ought to exist. However, this hypothesis seems inconsistent with the lack of observational evidence to support it. There have been many attempts to explain this paradox. From arguing that we are unique in the universe to extremely complicated theories involving super intelligences (see Wikipedia’s entry on Fermi’s Paradox).

For myself, I find the possibility of life existing on our doorstep in Europa’s ocean very exciting. Should the ocean exist, there is the minor technical difficulty of drilling through 100 kilometres of ice to reach it. But who knows - the aliens might start drilling from the bottom up and we’ll meet them half way.

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